Ionizing radiation from Chernobyl affects development of wild carrot plants. Abstract
Latest Chernobyl paper shows radiation effects of wild carrots!
Abstract
“Radioactivity released from disasters like Chernobyl and Fukushima is a global hazard and a threat to exposed biota. To minimize the deleterious effects of stressors organisms adopt various strategies. Plants, for example, may delay germination or stay dormant during stressful periods. However, an intense stress may halt germination or heavily affect various developmental stages and select for life history changes. Here, we test for the consequence of exposure to ionizing radiation on plant development. We conducted a common garden experiment in an uncontaminated greenhouse using 660 seeds originating from 33 wild carrots (Daucus carota) collected near the Chernobyl nuclear power plant. These maternal plants had been exposed to radiation levels that varied by three orders of magnitude. We found strong negative effects of elevated radiation on the timing and rates of seed germination. In addition, later stages of development and the timing of emergence of consecutive leaves were delayed by exposure to radiation. We hypothesize that low quality of resources stored in seeds, damaged DNA, or both, delayed development and halted germination of seeds from plants exposed to elevated levels of ionizing radiation. We propose that high levels of spatial heterogeneity in background radiation may hamper adaptive life history responses.”
Zbyszek Boratyński, Javi Miranda Arias, Cristina Garcia, Tapio Mappes, Timothy A. Mousseau, Anders P. Møller, Antonio Jesús Muñoz Pajares, Marcin Piwczyński & Eugene Tukalenko
Ionizing Radiation from Chernobyl and the Fraction of Viable Pollen
Tim Mousseau – latest Chernobyl paper in International Journal of Plant Sciences:
Oct 05, 2016
Pollen viability is an important component of reproductive success, with inviable pollen causing failure of reproduction. Pollen grains have evolved mechanisms to avoid negative impacts of adverse environmental conditions on viability, including the ability to sustain ionizing radiation and repair DNA. We assessed the viability of 109,000 pollen grains representing 675 pollen samples from 111 species of plants in Chernobyl across radiation gradients that spanned three orders of magnitude. We found a statistically significant but small and negative main effect of radiation on pollen viability rates across species (Pearson’s r = 0.20). Ploidy level and the number of nucleate cells (two vs. three) were the only variables that influenced the strength of the effect of radiation on pollen viability, as reflected by significant interactions between these two variables and background radiation, while there were no significant effects of genome size, pollen aperture type, life cycle duration, or pollination agent on the strength of the effect of radiation on pollen viability.
Introduction
Most organisms are susceptible to environmental perturbations—such as climate change, extreme weather events, pollution, changes in nutrient availability, and changes in ionizing radiation levels—but the effects of such perturbations on individuals, populations, and ecosystems are variable (Candolin and Wong 2012; IPCC 2013; Møller and Mousseau 2013). In order to better understand these effects and to predict how a given species would respond to environmental disturbances, a study of the specific effects at different stages of organisms’ life cycles is required. Since reproduction is a key phase in the life cycle of any organism, reproductive effects are of particular interest. In the case of the effects of ionizing radiation, the negative consequences for reproduction in response to acute irradiation have been studied for decades and are well established (review in Møller and Mousseau 2013). However, the effects of long-term chronic exposure to low dose radiation are poorly understood.
Pollen grains are susceptible to the effects of environmental perturbations, which can have significant negative consequences for plant reproduction through pollen limitation (Delph et al. 1997; Ashman et al. 2004). Potential negative environmental effects include those resulting from elevated levels of ionizing radiation (Koller 1943). Therefore, plants have mechanisms to protect themselves from such effects, such as DNA repair, bi- or trinucleate cells, or redundancies in the genome resulting from duplications.
The area around Chernobyl in Ukraine has proven particularly useful for studying the effects of radioactive contamination on ecological and evolutionary processes at a large spatial scale. The Chernobyl nuclear accident in April 1986 led to the release of between 9.35 × 103 and 1.25 × 104 petabecquerel of radionuclides into the atmosphere (Møller and Mousseau 2006; Yablokov et al. 2009; Evangeliou et al. 2015). These radioactive contaminants were subsequently deposited in the surrounding areas of Belarus, Russia, and Ukraine but also elsewhere across Europe and even in Asia and North America. The pattern of contamination is highly heterogeneous, with some regions having received much higher levels of radionuclides than others, owing to atmospheric conditions at the time of the accident (fig. 1). To this day, the Chernobyl area provides a patchwork of sites that can differ in radioactive contamination level by up to five orders of magnitude across a comparatively small area. Even decades after the accident, the amount of radioactive material remaining around Chernobyl is enormous (Møller and Mousseau 2006; Yablokov et al. 2009).
Fig. 1. Map of the distribution of radioactive contamination in the Chernobyl region, with pollen sampling locations marked. Adapted from DeCort et al. (1998).
Because of the unprecedented scale and global impact of the Chernobyl event, it is not surprising that it generated significant interest in both the scientific community and the general public. As a result, studies have been conducted to assess the consequences of Chernobyl for human health and agriculture as well as its biological effects, ranging from the level of DNA to entire ecosystems. Since ionizing radiation has long been well established as a mutagen (Nadson and Philippov 1925; Muller 1950), a large proportion of the research effort has focused on examining changes in mutation rates in areas that have been radioactively contaminated to different degrees as a result of the accident. Although there is considerable heterogeneity in the results of these studies, most have detected significant increases in mutation rates or genetic damage following the Chernobyl disaster, with the rates remaining elevated over the following 2 decades (reviewed in Møller and Mousseau 2006). For example, the mean frequency of mutations in Scots pine (Pinus sylvestris) is positively correlated with the level of background radiation, and it is 10 times higher in contaminated areas compared with control sites (Shevchenko et al. 1996). A study of Scots pine seeds detected elevated mutation rates within the exclusion zone over a period of 8 yr following the accident (Kal’chenko et al. 1995). In wheat (Triticum aestivum), the mutation rate was six times higher in radioactively contaminated areas compared with controls (Kovalchuk et al. 2000). Likewise, the frequency of chromosomal aberrations in two varieties of wheat grown within the Chernobyl exclusion zone 13 yr after the disaster was elevated compared with the spontaneous frequency of chromosomal aberrations in these cultivars (Yakimchuk et al. 2001). The levels of chromosome aberrations in onions (Allium cepa) were also positively correlated with the intensity of radioactive contamination in plants grown 20 yr after the accident (Grodzinsky 2006). Therefore, there is considerable evidence showing increased mutation rates in plants in the most contaminated sites (Møller and Mousseau 2015).
On the basis of the results of these studies, one might expect that a similar relationship between radiation level and the frequency of abnormalities would be seen in pollen. Indeed, Kordium and Sidorenko (1997) reported that the frequency of meiotic anomalies in microspore formation and the frequency of pollen grain viability was reduced in 8%–10% of the 94 plant species studied as a function of the intensity of gamma radiation 6–8 yr after the accident. In violets (Viola matutina), the proportion of viable pollen was negatively correlated with background radioactive contamination (Popova et al. 1991). While it is evident that plants differ in their susceptibility to ionizing radiation, the reasons for this variation are not entirely clear. It is likely that some species develop tolerance and/or resistance to mutagenic effects of radiation to a greater extent than others (Baer et al. 2007). For example, pollen of silver birch (Betula verrucosa), which grows in areas contaminated by the Chernobyl accident, showed elevated DNA repair ability compared with pollen from control areas, consistent with adaptation or epigenetic responses to increased radiation (Boubriak et al. 2008). There are also indications that genome size might affect the response of different species to radiation. Among the plants studied by Kordium and Sidorenko (1997), the rate of pollen viability decreased with increasing radiation to a higher degree in plants with smaller genomes (Barnier 2005), although the actual mechanism remains unknown. One potential explanation is that a larger genome might contain multiple copies of some genes as a result of duplication, rendering mutations in one of these copies less deleterious than if there were only a single copy present, although this explanation may not universally apply (Otto 2003).
In order to assess the effects of radioactive contamination on plant reproduction and to further assess species-specific differences in the effects of ionizing radiation on pollen viability, we analyzed pollen samples from plants growing in the Chernobyl region. We expected that the effects of radiation would differ among species, with some plants showing higher pollen inviability rates than others as a result of elevated radiation levels. A second objective was to test whether observed differences in pollen viability rates could be attributed to differences in phenotype among species, with possible explanatory factors including pollen size, the number of pollen apertures, ploidy, genome size, bi- or trinucleate cells, life span (annual vs. perennial), and pollination agent. We hypothesized that each of these factors could be related to the plants’ ability to resist or to tolerate radiation-induced mutations. Pollen size, genome size, and ploidy are all related to the amount of DNA and the number of copies of genes contained in the pollen grain. Because the pollen aperture—as the site of pollen germination—could be particularly susceptible to radiation-induced damage, we included the number of apertures as a potential explanatory variable. Furthermore, whether a plant is annual or perennial is related to individual longevity and, consequently, to the number of mutations that can accumulate over its lifetime as well as to the number of generations from the time of the Chernobyl accident until the time of sample collection. This may be particularly relevant for plants, given that germ tissue is derived from somatic tissues during each reproductive event as opposed to most animals, in which germ cells terminally differentiate very early during embryonic development (Buss 2006). Pollen viability depends on the ability of pollen to assess the integrity of its DNA and to repair the DNA of the generative nuclei before division (Jackson and Linskens 1980). This process is particularly important for binucleate pollen cells in which this happens during pollen germination, which is in contrast to trinucleate pollen cells, in which the need for DNA repair during pollen germination is less evident. DNA repair efficiency and adaptation of plants to chronic irradiation may also depend on the composition of radiation at the contaminated sites (Boubriak et al. 1992, 2008).
Across all plant species, we found a statistically significant relationship between radiation and the frequency of viable pollen of an intermediate magnitude (Cohen 1988). We also documented significant interactions between species and radiation, radiation and cell number, and radiation and ploidy. However, the significant effect of ploidy disappeared when both ploidy and whether cells were bi- or trinucleate were entered simultaneously in a single model. Most effects were small to intermediate in magnitude, as is commonly the case in studies of living organisms (Møller and Jennions 2002). We emphasize that our study included by far the largest sample size so far reported to detect effects of chronic radiation on pollen viability. However, we also emphasize the limits of our study. Many plant species could not be included simply because we could not locate multiple flowering specimens during our fieldwork. These and other sampling limitations reduced the number of pollen grains and the number of species that could be included.
Species differ in their susceptibility to radiation, as demonstrated for birds at both Chernobyl and Fukushima (Møller and Mousseau 2007; Møller et al. 2013; Galván et al. 2014), and in terms of adaptation to radiation (Galván et al. 2014; Møller and Mousseau 2016; Ruiz-González et al. 2016). The observed interspecific differences in radiation effects reported here for the proportion of viable pollen could be due to adaptation to radiation through tolerance of radiation-induced mutations or through induction of increased DNA repair in organisms living in contaminated areas. Another possibility is that some species are more resistant to radiation because of historical exposure in radiation hotspot areas with high natural levels of radiation (Møller and Mousseau 2013).
We observed a significant relationship between the proportion of viable pollen and the interaction between ploidy and radiation. Such a finding might suggest that resistance to deleterious effects of radiation is based on redundancy in the genome, where species with higher ploidy levels have an advantage if they have multiple copies of a given gene. We failed to detect an effect of selected physical attributes of pollen grains—such as genome size, pollen size, and aperture type—on the susceptibility of pollen to radiation. Furthermore, whether a plant was annual or perennial or whether it was insect or wind pollinated did not affect the proportion of viable pollen. Finally, whether plants produced bi- or trinucleate pollen had a significant effect on pollen viability, and the interaction between radiation and cell number was also significant.
While we confirmed the general finding of Kordium and Sidorenko (1997) that in approximately 10% of species the proportion of viable pollen is negatively correlated with radiation level, we were unable to reproduce their findings with respect to the overall magnitude of this effect. Our observed effect size was much smaller, and the slopes for individual species differed significantly from those reported by Kordium and Sidorenko (1997). Because more than 10 yr have passed between the two studies, we suggest that a change in radiation effects has taken place over time, for example, as a result of adaptation or accumulation of mutations. Another possible explanation for the discrepancy has to do with sample size, since our study included a much larger number of pollen samples and sampling locations than the study by Kordium and Sidorenko (1997). These explanations are not necessarily mutually exclusive.
Whereas other studies have demonstrated significant negative effects of radioactive contamination around Chernobyl on mutation rates and fitness in general, our study of pollen viability shows a very small effect, and some species even show positive relationships between pollen viability and radiation that is suggestive of adaptation to increased levels of radiation. However, on the basis of the current study, it is not possible to determine whether the observed heterogeneity reflects evolved adaptive responses or is the consequence of unmeasured selective effects on characters correlated with pollen viability, which could in part explain an overall positive effect of radiation (for a discussion of evolutionary responses in Chernobyl, see Møller and Mousseau 2016). Experimental approaches would be needed to decipher the mechanisms underlying the heterogeneity in plant responses observed here (Mousseau 2000).
The observed variability in susceptibility to radiation is a common finding in studies of the effects of radiation from Chernobyl (Møller and Mousseau 2007; Galván et al. 2011, 2014; Møller et al. 2013). While our results are consistent with earlier findings that DNA repair mechanisms may play an important role in adaptation to life in radioactively contaminated environments—especially for plants, which are sessile and hence cannot move to less contaminated areas—further research is required to test this explicitly. Finally, because of the observed differences in resistance to radiation among species, it is likely that even small overall effects of radiation—such as the one on the proportion of viable pollen described here—can have significant consequences for species composition and abundance at a given location and, therefore, for ecosystem characteristics and functioning.
In conclusion, we have found a statistically significant overall negative relationship between radiation intensity and the frequency of viable pollen in plants growing in contaminated areas around Chernobyl. The magnitude of this effect across species included in our study was intermediate. We only found a significant relationship between the proportion of viable pollen and ploidy × radiation interaction, bi- or trinucleate cells, and bi- or trinucleate cells × radiation interaction. This suggests that DNA repair mechanisms could play an important role for the ability of plants to resist increased radiation, at least when it comes to pollen formation.
Acknowledgments
We thank Puri López-García for use of a microscope for pollen counts. This work has benefited from the facilities and expertise of the cytometry platform of Imagif (Centre de Recherche de Gif; http://www.imagif.cnrs.fr). We thank Spencer Brown and Mickaël Bourge for their help with the flow cytometry measurements and Srdan Randić for help with pollen counts. Field collections for this study were supported in part by the Centre National de la Recherche Scientifique (France), the North Atlantic Treaty Organization Collaborative Linkage Grant program, the Fulbright program, the University of South Carolina College of Arts and Sciences, and the Samuel Freeman Charitable Trust. Two reviewers provided constructive criticism.
Read full paper at:
http://www.journals.uchicago.edu/doi/full/10.1086/688873
Dr. Timothy Mousseau speaks on consequences of Chernobyl and Fukushima
Dr Mousseau’s lecture on consequences of Chernobyl and Fukushima on plants and animals. Nov 4 2016
Dr. Timothy Mousseau speaks Nov. 4, 2016 to students and faculty of U of T about his research into the consequences of the Chernobyl and Fukushima nuclear accidents on plants and animals. His research shows increased mutations, genetic damage, poorer performing and malformed sperm, sterility, pollen inviability, cancers, cataracts, mental retardation, fewer species, fewer numbers, deadzones, and no evidence of adaptation.
His website is: http://cricket.biol.sc.edu/chernobyl/Chernobyl_Research_Initiative/Introduction.html
https://www.youtube.com/watch?v=cPWRinjQKyg
Fukushima Consequences of Radiation on Wildlife
By Pierre Fetet (translation by Hervé Courtois)
Source : http://www.fukushima-blog.com/2016/09/fukushima-consequences-de-la-radioactivite-sur-la-faune.html
Scientific studies conducted following the Fukushima disaster revealed little by little the consequences of radioactivity on the living and particularly on wildlife. Although published, they are nevertheless rarely circulated. This is why I would like to put a spotlight on some of them and publicize various observations which we do not hear much about, to counter the silly optimism to always relativize the consequences of low doses on life. Any dose of radiation, however small it be, has effects on the living: the ionizing radiation breaks the DNA molecules.
The birds
The feathers of birds take radioactive dust released into the atmosphere continuously by the wind. They therefore suffer permanent external irradiation.
We can see this dust by placing a contaminated bird on a radio-sensitive paper for a month. Here is an example with a bird picked in Iitate in December 2011.
Autoradiography also allows to highlight that the birds also undergo internal contamination.
Autoradiography of a bird revealing radioactive contamination in the plumage and stomach (Source Morizumi)
Yasuo HORI has also reported that some swallows Fukushima undergo depigmentation, as had already been found in Chernobyl. The Wild Bird Society of Japan also noted that the tail feathers of some Japanese swallows were not uniform.
It must be said that nests of swallows up to 1.4 million becquerels of radioactive cesium per kilogram (Bq / kg) have been found in the towns of Okuma and Namie. The nests of chickadees, were not better: 1.3 million Bq / kg.
Left: Swallow from Minamisoma (Fukushima Prefecture) – Right: deformed tail of a swallow from Kakuda (Miyagi Prefecture)
According to studies conducted by Tim Mousseau (University of South Carolina), the population of fifteen bird species living in contaminated areas of Fukushima prefecture decreases with time, with a 30% survival rate.
Another research focused on a falcon species returning in the same nest every year was also conducted by a team of scientists led by Naoki Murase (Nagoya University) at a distance of 100 to 120 km from the Fukushima Daiichi nuclear plant. The interest of this study is that raptors are at the top of a food chain and concentrate radionuclides accumulated by their prey. The authors have shown that the reproductive capacity of the bird was related to radiation measured directly under the nest : radioactivity affects the germline of the bird. The ability of birds to leave the nest fell from 79 to 55% in 2012 and 50% in 2013.
Another study finally published in 2015 by ASN and the Anders Møller laboratory (CNRS), focused on the total dose – internal and external – of birds.
It showed that 90% of the 57 species studied had been chronically exposed to radioactivity dose rate possibly affecting their reproduction.
Simplified representation of the level change of maximum exposure of adult birds (in dose rate) for 57 species of the bird community observed on 300 sites and four years of study. Compared to the range of variation (in blue) ambient dose rate measured on the sites and ranges (red) corresponding to various effects in birds published by the ICRP (2008) (Source IRSN)
So there are three factors that affect living organisms in contaminated areas: the ambient radiation (the dose that is received by being next to a radioactive object), the external contamination (radioactive dust that sticks to the skin, hair, feathers), and internal contamination (radionuclides ingested or trapped in organs).
The butterflies
The first scientific evidence of damage to a living organism by radioactive contamination due to the disaster of Fukushima Daiichi was delivered by the team of researcher Chiyo Nohara (University of Okinawa).
The study highlighted the physiological and genetic damage of a common butterfly of Japan, the maha zizeeria. In May 2011, some show relatively slight abnormalities. But the first female offspring of the first generation showed more serious defects, inherited by the second generation. Adult butterflies collected in September 2011, then showed more severe abnormalities than those collected in May: abortive hatching, infertility, size reduction, slow growth, high mortality and morphological abnormalities (Atrophied wings, curved or in excess number, malformed antennae, bumpy eyes, discolored).
Representative anomalies of butterflies fed contaminated leaves. (Source: Hiyama et al)
Aphids
In 2014, Shin-ichi Akimoto (Hokkaido University) found that about 10% of certain insects, such as aphids, have malformations in Fukushima. But their survival and their reproduction remain possible.
Sorini aphid T. From Fukushima. (A) normal morphology, (B) Level 3 malformation of the abdomen (Source: S. Akimoto)
The cows
The phenomenon of white patches (depigmentation) on the observed swallows in Fukushima and Chernobyl is also found on the cows of Masami Yoshizawa, at the Farm of Hope in Namie, a town located 14 km from the destroyed plant .
A cow of Masami Yoshizawa was brought to Tokyo in 2014 to the government for diagnosis (AFP Photo)
Horses
The biologist Hayato Minamoto reported the carnage suffered by Tokuei Hosokawa, an Iitate farmer who lost a hundred horses in two years. Iitate had suffered the brunt of the radioactive cloud from the Fukushima Daiichi plant in March-April 2011.
Iitate horses
Monkeys
Between April 2012 and March 2013, researchers led by Shin-ichi Hayama (Japan University of Life Sciences and Veterinary Sciences) analyzed the blood of 61 Japanese monkeys living in a forest 70 km from the Fukushima Daiichi nuclear power plant. The total concentration of cesium in monkeys muscles was between 78 and 1778 Bq / kg. Blood tests in these animals revealed a small quantity of white blood cells and red blood cells, which could make them more vulnerable. The decrease of blood cells was directly proportional to the concentration of cesium in the muscles, which suggests a dose-response correlation. Researchers estimate that exposure to radioactive materials contributed to hematological changes in Fukushima monkeys.
Drawing by Julien Loïs
Provisional Conclusion
The consequences of radioactivity on animals are visible to anyone who will bother to observe what happens. In this article, I focused on some animals only (there would be other cases to develop: the population decline of the cicadas, the increased cataract of rodents, etc.). Scientists could conduct similar studies on this strange animal that is man, but it would not be politically correct.
Yet this has already been done, in Hiroshima and Nagasaki, Chernobyl. For example, studies conducted between 1993 and 1998 on Ukrainian children permitted to observe a drop of blood cells, which was related to the exposure of each child to cesium depending on the place of residence. And yet, in Tokyo, from 2011 to 2014, Dr. Mita observed that white blood cells, especially neutrophils, decreased in children under 10 years old. (Which prompted him to move and to ask his patients to leave Tokyo). But no, do not say anything, and do not look into such matter.
In Japan, the denial of the danger is a must. The only mention of a nosebleed in a manga can cause a national affair and censorship … To speak of the negative consequences of the nuclear disaster at Fukushima Daiichi is not accepted.
You must rebuild, you must forget, you must think about the future. Institutionally, only one study is accepted, the monitoring of thyroids of children in Fukushima. That study is the screen that hides the forest of lies.
And yet, despite 131 thyroid cancers confirmed in June 2016, the official Japanese scientists refuse to see them as caused by radioactivity.
Pierre Fetet
To read more:
1) Scientific studies cited in this article
The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly, A. Hiyama, C. Nohara, S. Kinjo, W. Taira, S. Gima, A. Tanahara, J.-M. Otaki, 2012
Low blood cell counts in wild Japanese monkeys after the Fukushima Daiichi nuclear disaster, K. Ochiai, S. Hayama, S. Nakiri, S. Nakanishi, N. Ishii, T. Uno, T. Kato, F. Konno, Y. Kawamoto, S. Tsuchida, T. Omi, 2014
Morphological abnormalities in gall-forming aphids in a radiation-contaminated area near Fukushima Daiichi: selective impact of fallout?, S. Akimoto, 2014
Effects of the Fukushima Daiichi nuclear accident on goshawk reproduction, K. Murase, J. Murase, R. Horie, K. End, 2015
Radiological dose reconstruction for birds reconciles outcomes of Fukushima with knowledge of dose-effect relationships, J. Garnier-Laplace, K. Beaugelin-Seiller, C. Della-Vedova, J.-M. Métivier, C. Ritz, T. A. Mousseau, A. P. Møller, 2015
Cumulative effects of radioactivity from Fukushima on the abundance and biodiversity of birds, A. P. Møller, I. Nishiumi & T. A. Mousseau, 2015
2) Articles and file
Tchernobyl, une histoire pas si naturelle que ça (Pierre Fetet)
Non, Tchernobyl n’est pas devenu une réserve naturelle (Timothy Mousseau)
A Fukushima, les souris sont aveugles et les oiseaux ne chantent plus (Anne-Laure Barral)
According to a wildlife journalist, even in Tokyo some animals suffer mutations
Already few weeks ago a Japanese friend mentioned to me that he noticed very few insects this summer in Tokyo. This article now corroborates it.
If the wild life around Tokyo is that affected, how about the health of the people living there?
Frog having one eye only (photo by Eiki Sato, from October 10, 2016)
Ravages in Tokyo from the nuclear accident at Fukushima Daiichi 250km away.
The documentary film “Paradise Phantom” just came out. This documentary is about the stationary observations on animals by Eiki Sato, a wildlife journalist. The screening of this film took place at a movie theater in Suginami-ku, Tokyo on September 25, 2016.
Sato filmed for 170 hours various animals in the wild places of Tokyo, for example the banks of the Arakawa river, the fields near sports stadiums and Tokyo plants. These are real paradises for many living creatures, such as kestrels, shrikes, bats, frogs, dragonflies, even the gray beetles, animals that are not on the global red list threatened species.
The documentary shows that since two years animals with abnormalities are being observed . The cause of these abnormalities would be the accumulated radioactivity in the soil of Tokyo, according to Eiki Sato.
During his observations Eiki Sato found many types of deformities, due to mutations: Various insects affected with malformed or missing wing, or with curled wings, or abnormal eyes, unabling them to fly. Mosquito with bent spine, dragonflies with mishaped eyes unable to fly high. Birds with affected eyes, or feathers, unable to fly. Many also cannot reproduce, their population sharply decreasing.
http://www.tokyo-sports.co.jp/entame/entertainment/602104/
Mutational signatures of ionizing radiation in second malignancies
This article is important, and should be seen by as many people as possible, as this scientific study will impact greatly the future of our anti-nuclear cause.
By establishing the genetic signatures of any cancer caused by ionizing radiation, any future denial from the nuclear lobby is now impossible. Those scientifically established signatures will also be extremely helpful in court for any future suit from radiation victims.
Abstract
Ionizing radiation is a potent carcinogen, inducing cancer through DNA damage. The signatures of mutations arising in human tissues following in vivo exposure to ionizing radiation have not been documented. Here, we searched for signatures of ionizing radiation in 12 radiation-associated second malignancies of different tumour types. Two signatures of somatic mutation characterize ionizing radiation exposure irrespective of tumour type. Compared with 319 radiation-naive tumours, radiation-associated tumours carry a median extra 201 deletions genome-wide, sized 1–100 base pairs often with microhomology at the junction. Unlike deletions of radiation-naive tumours, these show no variation in density across the genome or correlation with sequence context, replication timing or chromatin structure. Furthermore, we observe a significant increase in balanced inversions in radiation-associated tumours. Both small deletions and inversions generate driver mutations. Thus, ionizing radiation generates distinctive mutational signatures that explain its carcinogenic potential.
Introduction
Exposure to ionizing radiation increases the risk of subsequent cancer. This risk exhibits a strong dose–response relationship, and there appear to be no safe limits for radiation exposure1. This association was first noted by March who observed an increased incidence of leukaemia amongst radiologists2. A leading cause of radiation-induced cancers appears to be exposure to medical radiation, either in the form of radiotherapy for an unrelated malignancy3 or diagnostic radiography4, 5. These iatrogenic tumours arise as de novo neoplasms in a field of therapeutic radiation after a latency period that can span decades6, and are not recurrences of the original cancer7.
Many, but not all, environmental carcinogens induce cancer by increasing the rate of mutation in somatic cells. The physicochemical properties of a given carcinogen govern its interaction with DNA, leading to recurrent ‘signatures’ or patterns of mutations in the genome. These can be reconstructed either from experimental model systems8, 9 or from statistical analyses of cancer genomes in exposed patients10, 11, 12. Ionizing radiation directly damages DNA, and can generate lesions on single bases, single-stranded nicks in the DNA backbone, clustered lesions at several nearby sites and double-stranded DNA breaks13. In experimental systems exposed to radiation, including the murine germline and Arabidopsis thaliana cells, ionizing radiation can cause all classes of mutations, with possible enrichment of indels14, 15, 16, 17, 18, 19, 20, 21, 22. Targeted gene screens in radiation-induced sarcoma have indicated an increased burden of deletions and substitutions with frequent inactivation of TP53 and RB1 (refs 23, 24, 25). In addition, a transcriptome profile that represents a state of chronic oxidative stress has been proposed to be specific to radiation-associated sarcoma26.
We studied the genomes of 12 radiation-associated second malignancies of four different tumour types: osteosarcoma; spindle cell sarcoma; angiosarcoma; breast cancer. These were secondary tumours that arose within a field of therapeutic ionizing radiation and were not thought to be recurrences of the original malignancy treated with radiation. We chose this experimental design for several reasons: the tumours are classic radiotherapy-induced cancers with high attributable risks for the radiation exposure; the radiation exposure occurs over a short time period relative to the evolution of the cancer; and the mutational signatures of sporadic breast cancers and sarcomas have been well documented10, 27, 28, 29. It should be noted that in the absence of biomarkers, a diagnosis of a tumour being radiation-induced cannot be definitively made (see Supplementary Note 1 for clinical details and further discussion).
We subjected these 12 tumours, along with normal tissues from the same patients, to whole-genome sequencing and obtained catalogues of somatic mutations. We compared our findings to 319 radiation-naive breast cancers and sarcomas processed by the same sequencing and bioinformatics pipeline: 251 breast tumours; 33 breast tumours with pathogenic BRCA1 or BRCA2 germline mutations; 35 osteosarcomas (see Methods for cohort details). In addition, we validated our findings in a published series of radiation-naïve and radiation-exposed prostate tumours from ten patients30.
The main aim of our analyses was to search for tumour-type independent, overarching signatures of ionizing radiation. Overall we identified two such signatures in radiation-associative second malignancies, an excess of balanced inversions and of small deletions.
To read more :
http://www.nature.com/ncomms/2016/160907/ncomms12605/full/ncomms12605.html
Honouring the Life and Work of Chiyo Nohara
Chiyo Nohara, who died aged 60, was member of the research team that published the first scientific evidence of harm to a living organism from radioactive contamination due to the accident at the Fukushima Daiichi Nuclear Power Plant.
Courage and heroism
In August 2012, the journal Nature published evidence that artificial radionuclides from the Fukushima Daiichi Nuclear Power Plant caused physiological and genetic damage to the pale grass blue butterfly Zizeeria mara [1]. Among the team at University of the Ryukyus Okinawa undertaking the research was a mature student in her first year, Chiyo Nohara. Chiyo died on 28 October 2015 at the age of 60 from a heart attack. Chiyo was a scientist who set out to protect her fellow human beings despite great pressure from the authorities and at great risk to her own life.
Chiyo once said to a friend [2] “No matter how much you researched and knew, it would be pointless if you die before letting the world know about what you learned”. Fortunately, Chiyo’s research was published, and provided the first scientific evidence of harm to a living organism from the accident at Fukushima. I will not describe the research itself, which is available in print [1]. (See also [3] Fukushima Mutant Butterflies Confirm Harm from Low-Dose Radiation, SiS 56.) Instead, I would like to concentrate on her response to the accident at Fukushima, and pay tribute to the intelligence, courage, and energy of Nohara and her team-mates in initiating the research, in undertaking the fieldwork, conducting laboratory experiments, and later defending their work against critics.
Chiyo was born 8 May 1955 in Ube city of Yamaguchi prefecture. She studied economics at Okayama University and Aichi University; taught accounting at university level, publishing numerous papers and was involved in public auditing at a local and national government level. But in 2010, at the age of 55, partly because her own daughter suffered allergies, Chiyo became interested in environmental health. She resigned from her university post and enrolled in the Biology graduate school programme of the Faculty of Science at University of the Ryukyus.
Accident at Fukushima Daiichi nuclear power plant
When the accident at Fukushima occurred in March 2011, Chiyo was only in her first year of study. Nevertheless, she persuaded her team that research in the Fukushima area was of crucial importance, and that it had to be started immediately. She had already been active in donating money and supplies to the victims of the tsunami and earthquake, but she said [4]:“I want to go to Fukushima. I want to see the stricken areas with my own eyes”. She said she “wanted to do anything” to help the people affected by the accident.
The graduate team, led by Associate Professor Joji Otaki, specialised in molecular physiology, and had been researching the mechanism of the pale grass blue butterfly’s (Zizeeria maha) peculiar colour patterns which are influenced by environmental conditions such as temperature. He saw that this species of butterfly could be used as an environmental indicator.
Conducting research in the contaminated territories
After much heart-searching three members of the graduate school decided to go to the contaminated territories of Fukushima. They all signed a written disclaimer [4]: “I am fully aware of the dangers of my activities in relatively high radiation level areas”. But several days before their scheduled trip to Fukushima, they were summoned to the Dean’s office. Chiyo and her team were subjected to some aggressive and unpleasant questioning from the Dean, the sub-Dean, and another member of staff. They were challenged with regard to their preparation and planning, and about the reaction they would elicit from people in Fukushima prefecture “when they see a team of the University of the Ryukyus pursuing butterflies with butterfly nets, while they are desperately searching for missing relatives [from the tsunami].”
Eventually, permission was given, subject to the correct radiological protection measures and strict crisis management planning in the event of another explosion at the nuclear power station. Interestingly the sub-Dean paid his respect to the team later saying that many research teams will not take risks for fear of losing funds but “this research team doesn’t care about such risks. They just want to know what is happening there. I support their work, but they make me nervous”.
The team left on 13 May 2011 for a six day field trip. They carried a Geiger counter to record radiation levels and gave themselves a strict 20 minute time limit at any one site. If no butterflies were found they moved on. They visited 15 sites in 4 prefectures (Tokyo, Ibaraki, Fukushima, Miyagi), and flew back to Okinawa on the 18 May with 144 butterflies.
Chiyo worries about her health
The work was continued over the next months in the university laboratories in Okinawa, and in September the team visited Fukushima prefecture once again and collected more specimens. Part of the laboratory research involved feeding the butterflies on oxalis corniculata contaminated by radionuclides from the Fukushima area. It was Chiyo and her husband who made the trips to the contaminated territories to collect contaminated oxalis – 15 trips in the space of 18 months. Inevitably Chiyo worried about her health. A friend said [2] “every time she went to Fukushima to collect butterflies, and every time she measured the radiation level of the contaminated oxalis, her physical condition deteriorated.But she did not want young students to do the job.”
The team collected first-voltine adults in the Fukushima area in May 2011 and some of these showed abnormalities. They reared two generations of progeny in the laboratories in Okinawa and found that although these had not been exposed to radiation, they had more severe abnormalities. They were also able to produce similar abnormalities in individuals from non-contaminated areas by external and internal low-dose exposures. Adult butterflies were collected from the Fukushima area in September 2011, and these butterflies showed more severe abnormalities than those collected in May. The team concluded that the artificial radionuclides from the Fukushima nuclear power plant had caused physiological and genetic damage to this species of butterfly.
Research “important and overwhelming in its implications”
The research was first published in August 2012 in Nature and international response was immediate[2]. The BBC detailed the research findings and included the comment that the study was “important and overwhelming in its implications for both the human and biological communities in Fukushima” [5]. Le Monde in France was more explicit, saying that although officially no-one has yet died from the effects of the radiation from Fukushima, many experts believe that people will fall ill and die in the years to come [6]. The BBC and the German TV company, ARD, came to interview Professor Otaki in Okinawa, and the American TV networks ABC, CNN and Fox also covered the story.
The research elicited a huge number of comments (276 139 in the first six months up to January 2013, according to the publisher’s website). The comments were answered by Chiyo and the team in a new paper in 2013 [7]. Eleven points were discussed in depth including the choice of this species as an environmental indictor, the possibility of latitude-dependent forewing-size reduction, the rearing conditions and the implications of the accumulation of genetic mutations. Many of the comments expressed were unscientific and politically motivated and could not be answered for that reason.
In Japan the research is not widely known
The mainstream Japanese media did not report the significance of this research, except for a few minor references. On personal blogs and Twitter accounts the research findings were widely disseminated but not always positively. The lack of press freedom in Japan since the Fukushima accident is very disquieting. In the 2010 Press Freedom Index of countries in the world, Japan ranked 11. By 2015 it had fallen to 61, and this is in large part due to secrecy about the accident at Fukushima [8]. In Europe and the United States, pictures of the pale grass blue butterfly, Z. maha and its abnormalities, post-Fukushima, can be accessed within seconds, but not so in Japan. The Japanese government’s response to the accident has been overwhelmingly to give falsely reassuring “information”. An example is Prime Minister Abe declaring to the Olympic Bid Committee in 2013 that “the Fukushima Daiichi nuclear plant is under control”, which is clearly not true [9].
It is an uphill struggle. Scientists and non-scientists in the West have a duty to help the Japanese people. Just as at Chernobyl, there is [10] “a fragile human chain made up, in the East, of activists in a country trapped in radioactive contamination and in the West, by activists who support them against scientific lies.” In 2014, Chiyo travelled to Geneva to present her research at the Forum on the Genetic Effects of Ionising Radiation, organized by the Collective IndependentWHO [11]. She was already ill. IndependentWHO have published the proceedings of this Forum and dedicated them to Chiyo Nohara, with the words “She died in the cause of scientific truth”. Within the pages of Science in Society, dedicated to scientific independence, I salute her. But we would be doing Chiyo Nohara a disservice if we did not add that the implications of her research are that no-one, and especially not children, should be living in the areas contaminated by the accident at Fukushima.
Susie Greaves
ISIS Report 07/01/16
Published first in ISIS – Institute of Science in Society
http://www.i-sis.org.uk/Honouring_the_Life_and_Work_of_Chiyo_Nohara.php
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References
1 – Hiyama A, Nohara C, Kinjo S, Taira W, Gima S Tanahara A and Otaki JM. The biological impacts of the Fukushima nuclear accident on the pale grass blue butterfly.Nature Scientific Reports2, 570, DOI: 10.1038/srep00570
2 – Obituary of Chiyo Nohara by Oshidori Mako in Days Japan, December issue, 2015, Vol.12, No.12, p.23.
3 – Ho M W. Fukushima mutant butterflies confirm harm from low dose radiation. Science in Society 56, 48-51, 2012.
4 – “Prometheus Traps: Pursuing Butterflies”, Nakayama Y, Asahi Shimbun, 2015 (Series no.4: 12 July 2015:, no.5: 14 July 2015, no.6: 15 July 2015, no.7: 16 July, 2015, no.8: 17 July 2015, no.10: 19 July 2015)
5 – “Severe abnormalities found in Fukushima butterflies”, Nick Crumpton, 13 August 2012, http://www.bbc.co.uk/news/science-environment-19245818
6 – “Des papillons mutants autour de Fukushima”, Philippe Pons, 15 August 2012, http://www.lemonde.fr/planete/article/2012/08/15/des-papillons-mutants-autour-de-fukushima_1746252_3244.html
7 – Hiyama A, Nohara C, Taira W, Kinjo S, Iwata M and Otaki JM, BMC Evolutionary Biology 2013, 13:168 http://www.biomedcentral.com/1471-2148/13/168 http://www.biomedcentral.com/content/pdf/1471-2148-13-168.pdf)
8 – “Japan slips in press freedom index.” Toko Sekiguchi, Wall Street Journal: Japan Real Time, 13 February 2015. http://blogs.wsj.com/japanrealtime/2015/02/13/japan-slips-in-press-freedom-rankings/
9 – “Japan Olympic win boosts Abe but Fukushima shadows linger”, Elaine Lies, Reuters, 9 September 2013, http://www.reuters.com/article/us-olympics-2020-japan-idUSBRE98806P20130909#ujqbOt12wDCbMa2v.97
10 – Tchertkoff W, Le crime de Tchernobyl: le goulag nucleaire. Actes Sud (2006)
11 – Collective IndependentWHO, Proceedings of the Scientific and Citizen Forum on the Genetic Effects of Ionising Radiation, (2015) http://independentwho.org/media/Documents_Autres/Proceedings_forum_IW_november2014_English_02.pdf
http://independentwho.org/en/2016/01/16/honouring-chiyo-nohara/
Nuclear accidents make mutant bugs and birds
Biologist Timothy Mousseau has spent years collecting mutant bugs, birds and mice around Chernobyl and Fukushima. In a DW interview, he shares some surprising insights into the effects of nuclear accidents on wildlife.
DW: Professor Timothy Mousseau, did you collect these mutant firebugs [pictured at the top of the page]?
Timothy Mousseau: Yes, the firebugs are really an eye-opener. My research partner Anders Moller and I were visiting Chernobyl on April 26, 2011. We were wandering around Pripyat collecting flowers, to study their pollen, when Anders reached down to the ground and pulled up this little bug with red and black markings. He said: “Tim, look, it’s a mutant – it’s missing an eye spot!”
From then on we started collecting these little bugs in each place we visited, from the most contaminated parts of the Red Forest to relatively clean areas in abandoned villages. Eventually we had several hundred of these little critters. It was very obvious that deformed patterns were much more prevalent in areas of high contamination.
This is just one of many similar anecdotes about the deformed critters of Chernobyl. Literally every rock we turn over, we find a signal of the mutagenic properties of the radiation in the region.
A pair of great tit birds collected near Chernobyl – left is normal, the individual on the right has a facial tumor
Is there a threshold of radiation below which there’s no effect?
The impact of radiation on rates of mutation, cancer and mortality varies a good deal by species. But statistically, there’s a simple relationship with dose. Small dose, small effect; big dose, big effect. There doesn’t appear to be a threshold below which there’s no effect.
Interestingly, organisms living in nature are much more sensitive to radiation than lab animals – comparing mice raised in labs and mice in the wild, exposed to identical levels of ionizing radiation, the mortality rate among wild mice is eight or 10 times that of lab mice. It’s because lab animals are protected from most stressors – like cold or hunger.
Are plants and trees affected too?
Yes, we’ve collected a lot of deformed pollen. Seen a lot of deformed trees, too. Pines often show growth-form abnormalities, even in normal areas with no radionucleotide contamination. Sometimes it’s an insect infestation, sometimes a hard freeze at the wrong time – you can find such anomalies anywhere.
But in contaminated areas of Ukraine, we have a correlation between frequency of abnormality and the Chernobyl event. It’s pretty strong evidence. There was a recent paper showing a very similar phenomenon in Fukushima. The trees there are very young, but will likely also be twisted up in knots 30 years from now!
Mousseau’s field crew collecting pollen and insect samples on the left, with the Chernobyl reactor in the distance. Right, a mutant pine tree at Chernobyl
What are the long-term effects of radiation on animal or plant species in contaminated areas? They’ve had their genomes altered. Will mutants persist?
Well, in the long run, no. The thing is, some background rate of mutations happens constantly in every species, even in uncontaminated areas – albeit at a much lower rate than in areas contaminated by nuclear accidents. So most genetic variants have been tried already. The great majority are either neutral or slightly deleterious. If a mutation had any benefit to offer, it would already be there in the population.
So the long-term effect of nuclear accidents on biodiversity is … none?
Yes, that’s right. Over evolutionary time, we expect that populations will return to normal after the mutagen disappears. Radionucleotides decay, hot sites eventually cool down, mutations become less frequent again, and healthy animal and plant populations recolonize the sites. So the genetic status quo ante returns – except if mutations have occurred that permanently enhance fitness, but that’s very rare.
Mousseau (left) and colleague Anders Moller recording measurements in the field at Chernobyl
Some mutations might persist for a while if they’re adaptive during the hot phase. For example, there’s selection for animals whose cells produce a higher antioxidant load, which makes them more resistant to the effects of ionizing radiation. But that protection comes at a metabolic cost. After radiation levels die down, those variants will be selected back out of the population.
Where things get complicated is when the harmful mutations are recessive, that is, when it takes two copies [one for each chromosome] for the expression of the mutation. Many mutations fall into this category. They can accumulate in populations because they’re not expressed until two copies come into the same individual [one from the mother, the other from the father].
Because of this, populations can be affected by such mutations for many generations even after the mutagen is removed, and also, via dispersal, in populations that were never affected by the mutagen.
How can radioactive contamination interact with other problems that affect ecosystems, like habitat loss or climate change?
Certainly climate change is an additional stressor that is likely to interact with radiation to affect populations. We have demonstrated that while swallows in most places have moved their breeding dates forward in response to warming, in the Chernobyl area they are actually delayed. We hypothesize that this is due to the stress from the radioactive contaminants.
The Red Forest near Chernobyl in Ukraine presents a high risk of fire, as a lack of bacteria prevents the trees from decaying
The biggest fear at present is related to the observation of hotter and drier summers in Ukraine, and the resulting increase in number and size of forest fires. Last summer there were three large fires, and one of them burned through some very contaminated areas.
We have predicted that such events could pose a significant threat to both human populations and the environment via re-suspension and deposition of radionuclides in the leaf litter and plant biomass.
In addition to the threat of catastrophic wildfire spreading nuclear contamination, birds and mammals also move around. Do they absorb radioactive elements in their food and water in contaminated sites, carry them elsewhere, thus dispersing the contamination more widely?
Do animals move radionuclides? Yes! I did a study years ago that showed very significant amounts of radionuclides are exported every year by birds. But it seems unlikely that the amount is enough to cause measurable health effects – unless you’re eating the birds. It is known that some people living outside the Chernobyl Exclusion Zone are getting very significant doses from hunting the contaminated wild boar that leave the zone.
Mouse with cataract collected near Chernobyl – the more radioactive the site, the higher the frequency of defects
This year marks five years since the Fukushima accident, and 30 years since Chernobyl. How long will the contaminated zones around Chernobyl and Fukushima be mutagenic and dangerous?
Chernobyl was a nuclear fire and ongoing fission event for 10 days, with strontium, uranium and plutonium isotopes strewn into the landscape. They have long half-lives, so many areas will remain hazardous for centuries, even thousands of years.
Fukushima was largely a cesium event, and cesium radionucleotides have a relatively short half-life. The area will mostly naturally decontaminate itself within decades, at most within a couple hundred years.
Timothy Mousseau is a professor of biological sciences at the University of South Carolina in Columbia, South Carolina. He is one of the world’s leading experts on the effects of radionucleotide contamination from nuclear accidents on wild bird, insect, rodent, and plant populations.
Interview: Nils Zimmermann
Mutations, DNA damage seen in Fukushima forests, says Greenpeace
Conservation group Greenpeace warned on Friday that the environmental impact of the Fukushima nuclear crisis five years ago on nearby forests is just beginning to be seen and will remain a source of contamination for years to come.
The March 11, 2011 magnitude-9.0 undersea earthquake off the nation’s northeastern coast sparked a massive tsunami that swamped cooling systems and triggered reactor meltdowns at the Fukushima No. 1 nuclear plant.
Radiation spread over a wide area and forced tens of thousands of people from their homes — many of whom will likely never return — in the worst nuclear accident since Chernobyl in 1986.
As the fifth anniversary of the disaster approaches, Greenpeace said signs of mutations in trees and DNA-damaged worms were beginning to appear, while “vast stocks of radiation” mean that forests cannot be decontaminated.
In a report, Greenpeace cited “apparent increases in growth mutations of fir trees, … heritable mutations in pale blue grass butterfly populations” as well as “DNA-damaged worms in highly contaminated areas.”
The report came as the government intends to lift many evacuation orders in villages around the Fukushima plant by March 2017, if its massive decontamination effort progresses as it hopes.
For now, only residential areas are being cleaned in the short-term, and the worst-hit parts of the countryside are being omitted, a recommendation made by the International Atomic Energy Agency.
But such selective efforts will confine returnees to a relatively small area of their old hometowns, while the strategy could lead to re-contamination as woodlands will act as a radiation reservoir, with pollutants washed out by rains, Greenpeace warned.
The conservation group said its report relies largely on research published in peer-reviewed international journals.
But “most of the findings in it have never been covered outside of the close circles of academia”, report author Kendra Ulrich said.
The government’s push to resettle contaminated areas and also restart nuclear reactors elsewhere around the country that were shut down in the aftermath of the crisis are a cause for concern, Ulrich said, stressing it and the IAEA are using the opportunity of the anniversary to play down the impact of the radiation.
“In the interest of human rights — especially for victims of the disaster — it is ever more urgent to ensure accurate and complete information is publicly available and the misleading rhetoric of these entities challenged,” she said.
Scientists, including a researcher who found mutations of Fukushima butterflies, have warned, however, that more data are needed to determine the ultimate impact of the Fukushima accident on animals in general.
Researchers and medical doctors have so far denied that the accident at Fukushima would cause an elevated incidence of cancer or leukemia, diseases that are often associated with radiation exposure.
But they also noted that long-term medical examination is needed, especially due to concerns over thyroid cancer among young people — a particular problem for people following the Chernobyl catastrophe.
http://www.japantimes.co.jp/news/2016/03/04/national/science-health/mutations-dna-damage-seen-fukushima-forests-greenpeace/#.VtmtlObzN_m
Radiation fears as report shows Fukushima fir trees to be growing strangely
TOKYO — Following the events of the 2011 Tohoku earthquake and tsunami and the subsequent meltdowns at the Fukushima Daiichi nuclear power plant complex, radiologists in Japan have been closely observing the area for potential changes. A new report by the National Institute of Radiological Sciences now suggests that the fir trees in Fukushima may be exhibiting strange growth patterns, with the radiation from the disaster being named as a possible factor.
The report, published on the organisation’s website on August 28, states that when comparing fir trees from within the affected zone to those from areas with lower radioactivity, the fir trees in the affected area were increasingly found to be stunted and exhibiting signs of morphological change, particularly bifurcation, the splitting of a body into two parts, i.e. “branching.”
Each year of a healthy fir tree’s growth sees it growing directly upward while also putting out two horizontal branches. Scientists have noted, however, that some of the trees in the affected areas are only branching off into two separate directions at the tip, and exhibiting lack of upward growth.
The changes can be identified in the images above left, which were included with the report. Image A shows a normal example of growth. Note the vertical central branch. Photo B shows a trunk which has entirely split into two, and photo C shows horizontal growth only, with a distinct lack of vertical growth. The red arrows indicate where bifurcation has occurred. You can see in image C how the central, vertical branch of the tree which should be growing upward is missing entirely.
The investigation was conducted in January of this year, with trees examined in Okuma, Fukushima (3.5 kilometres from the nuclear plant), and two locations in Namie, Fukushima (8.5 and 15 kilometres from the plant). Radiation levels in Okuma were recorded at 33.9 microsieverts, and in Namie, the levels were 19.6 and 6.85 microsieverts, respectively. These trees were compared against trees in the north of neighbouring Ibaraki Prefecture from an area with a microsievert reading of 0.13.
Between 100 and 200 trees in each location were examined for changes, with the effect seen more often in the areas with higher levels of radiation. 90% of the trees examined in Okuma exhibited some degree of morphological change, a number which fell to 40% and 30% in Namie, and to less than 10% in northern Ibaraki Prefecture.
The correlation between the frequency of the morphological change and the proximity to the Fukushima Daiichi site/level of radiation recorded suggests that it is likely — but as yet not confirmed — that the changes are connected to the increase in background radiation.
However, the report notes that this particular morphological change has been identified in other areas and can be attributed to a range of other factors including environmental changes and as a result of pest damage. The report states that rather than attributing this change directly to the nuclear disaster, researchers are instead presenting evidence that proves that this change is seen more often when radiation is a contributing factor.
Source: Report on Morphological Changes to Fir Trees in Areas with High Radiation, National Institute of Radiological Sciences
Source: Japan Today
Morphological defects found in Japanese fir trees around Fukushima nuclear plant
Radiation spewed out by the crippled Fukushima No. 1 nuclear power plant may be responsible for differences in the growth of native Japanese fir trees in the area.
Researchers primarily from the National Institute of Radiological Sciences said Aug. 28 that many fir trees near the plant, as well as other areas, had undergone “morphological defects.”
They intentionally avoided words like abnormality, but used morphological defects and change.
Their studies showed that the changes occurred more frequently in areas with higher air rates of radiation.
“But it is still unclear whether the phenomenon has been caused by radial rays,” a team member concluded, adding that exposure to higher levels of radiation is “one possible cause.”
Conducted in January, the survey covered the town of Okuma in Fukushima Prefecture, located 3.5 kilometers from the plant, where radiation levels of 33.9 microsieverts per hour were detected, and two locations in the town of Namie, also in the prefecture.
While one of the Namie investigation sites is 8.5 km from the plant and measured 19.6 microsieverts per hour, readings of 6.85 microsieverts were detected at the other spot, located 15 km from the facility.
All the sites are within the government-designated difficult-to-return zone, meaning that the residents were evacuated and are prohibited from living there.
The team also examined firs in distant Kita-Ibaraki, Ibaraki Prefecture, which had radiation levels of 0.13 microsieverts per hour, for comparison.
In each of the four sites, the scientists checked 100 to 200 fir trees.
They found that more than 90 percent of firs in the Okuma site were not growing normally. Fir tree boles normally extend upward with two or so branches arising from them horizontally each year. But this was not the case.
Similar changes in shape were found in more than 40 percent of firs and around 30 percent of the trees, respectively, in the two Namie locations. Less than 10 percent of fir trees in the Kita-Ibaraki survey site also were different.
According to the NIRS, findings of studies concerning the 1986 Chernobyl nuclear disaster and other research revealed that conifers, such as firs and pine trees, are vulnerable to the effects of radiation.
However, the scientists noted that the problems reported in their latest survey may have been caused by animals, tree sickness or cold weather, not by exposure to strong radiation.
The Environment Ministry has been examining the impact of radial rays on local ecosystems since the nuclear crisis unfolded at the Fukushima nuclear plant four years ago. The NIRS study is part of those ministry efforts.
The governmental agency has to date monitored 44 kinds of animals and plants in areas around the damaged facility, but no other significant changes or abnormalities have been reported.
‘LABORATORY EXPERIMENTS ESSENTIAL’
Tomoko Nakanishi, a professor of radiation plant physiology at the University of Tokyo, said the latest findings are invaluable as researchers have difficulty doing surveys in the difficult-to-return zone due to high radiation readings.
“There had been so little data on such areas,” she said.
But Nakanishi also pointed out it will require further research to conclude the morphological changes have been caused by exposure to radial rays.
“Other factors may have affected fir trees,” Nakanishi said. “Researchers need to examine through lab experiments what will happen when firs are exposed to high levels of radiation.”
Source: Asahi Shimbun
http://ajw.asahi.com/article/0311disaster/fukushima/AJ201508290045
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