Ultrastructural Analysis of Large Japanese Field Mouse (Apodemus speciosus) Testes Exposed to Low-Dose-Rate (LDR) Radiation after the Fukushima Nuclear Power Plant Accident.

Since the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, great attention has been paid to the impact of chronic low-dose-rate (LDR) radiation exposure on biological systems. The reproductive system is sensitive to radiation, with implications connected to infertility. We investigated the testis ultrastructure of the wild large Japanese field mouse (Apodemus speciosus) from three areas contaminated after the FDNPP accident, with different levels of LDR radiation (0.29 µSv/h, 5.11 µSv/h, and 11.80 µSv/h). Results showed good preservation of the seminiferous tubules, comparable to the unexposed animals (controls), except for some ultrastructural modifications. Increases in the numerical density of lipid droplet clusters in spermatogenic cells were found at high levels of LDR radiation, indicating an antioxidant activity rising due to radiation recovery. In all groups, wide intercellular spaces were found between spermatogenic cells, and cytoplasmic vacuolization increased at intermediate and high levels and vacuolated mitochondria at the high-level. However, these findings were also related to the physiological dynamics of spermatogenesis. In conclusion, the testes of A. speciosus exposed to LDR radiation associated with the FDNPP accident showed a normal spermatogenesis, with some ultrastructural changes. These outcomes may add information on the reproductive potential of mammals chronically exposed to LDR radiation.

Optimizing chemical-induced premature chromosome condensation assay for rapid estimation of high-radiation doses.

In the event of exposure to high doses of radiation, prompt dose estimation is crucial for selecting appropriate treatment modalities, such as cytokine therapy or stem cell transplantation. The chemical-induced premature chromosome condensation (PCC) method offers a simple approach for such dose estimation with significant radiation exposure, but its 48-h incubation time poses challenges for early dose assessment. In this study, we optimized the chemical-induced PCC assay for more rapid dose assessment. A sufficient number of PCC and G2/M-PCC cells were obtained after 40 h of culture for irradiated human peripheral blood up to 20 Gy. By adding caffeine (final concentration of 1 mM) at 34 h from the start of culture, G2/M-PCC index increased by 1.4-fold in 10 Gy cultures. There was also no significant difference in the G2/M-PCC ring frequency induced for doses 0 to 15 Gy between our 40-h caffeine-supplemented chemical-induced PCC method and the conventional 48-h PCC assay.

Baseline micronucleus frequencies and 60Co cytokinesis-block micronucleus assay dose-response curve for biodosimetry in Vietnam.

This study aims to establish baseline micronucleus (MN) frequencies from various populations of residents in Vietnam and develop a 60Co dose-response curve for the cytokinesis-block micronucleus (CBMN) assay. Blood samples were exposed in vitro to a 60Co source at a dose rate of 275 mGy per min in a range of 0.1 to 4.0 Gy. MN background frequencies were 4.5 ± 3.2, 7.3 ± 4.6, 7.0 ± 3.8 and 13.1 ± 6.7 in 1000 binucleated (BN) cells for 96 healthy donors, 22 male radiation workers and 12 breast cancer patients, respectively. Blood samples from three healthy donors were used to generate the MN dose-response curve: y = C + (0.0496 ± 0.0069)D + (0.0143 ± 0.0026)D2. This curve was verified through an inter-laboratory comparison (RENEB ILC 2021). Our findings highlight the significance of the CBMN assay as an additional essential tool for biodosimetry in Vietnam.

Derivation of Naïve Human Embryonic Stem Cells Using a CHK1 Inhibitor.

Embryonic development is a continuum in vivo. Transcriptional analysis can separate established human embryonic stem cells (hESC) into at least four distinct developmental pluripotent stages, two naïve and two primed, early and late relative to the intact epiblast. In this study we primarily show that exposure of frozen human blastocysts to an inhibitor of checkpoint kinase 1 (CHK1) upon thaw greatly enhances establishment of karyotypically normal late naïve hESC cultures. These late naïve cells are plastic and can be toggled back to early naïve and forward to early primed pluripotent stages. The early primed cells are transcriptionally equivalent to the post inner cell mass intermediate (PICMI) stage seen one day following transfer of human blastocysts into in vitro culture and are stable at an earlier stage than conventional primed hESC.

Mitotic index maximization with no effect on radiation-induced dicentric chromosome frequency.

PURPOSE: The dicentric chromosome (Dic) assay, which is the gold standard for biological dose assessment in radiation emergency medicine, requires an analysis of at least 500 lymphocyte metaphases or 100 Dic aberrations. Therefore, peripheral blood culture conditions able to obtain a high frequency of metaphases for efficient dose evaluation should be optimized. However, the type of blood cultures [i.e. whole blood (WB) or isolated peripheral blood mononuclear cell (PBMC)-culture] and blood volume differ between biodosimetry laboratories. The purpose of this study is to investigate the blood volume at which a high mitotic index (MI) is obtained in peripheral WB-culture and isolated PBMC-culture, and to examine the possible effect of blood volume on radiation-induced Dic frequency. MATERIALS AND METHODS: Peripheral blood was collected from three healthy donors with their informed consent. The complete and differential blood counts were performed using an automated hematology analyzer. After blood count, peripheral blood was irradiated with 0 or 2 Gy X-ray. Blood was cultured with phytohemagglutinin (180 µg/ml) and demecolcine　(0.05 µg/ml) for 48 h. The MI and Dic frequency were analyzed in 5, 10, 15, 20, 25, and 30% WB-cultures and 0.6, 1.2, 1.8, 2.4, 3.0, 3.6, and 4.2 ml WB-equivalent PBMC-cultures. RESULTS: In WB-culture, MI showed the highest value (∼22%) in 5-15% WB-culture and then gradually decreased to ∼9% with 30% WB-culture. MI peaked at 36 and 31% in 1.8 and 2.4 ml-WB equivalent volumes for PMBC-cultures, respectively. MI progressively decreased as the amount of PBMCs increased. Although individual differences were observed in the MI values among the three subjects, all the subjects showed the same tendency and higher MI was seen in PBMC than WB-cultures. However, these factors had no significant impact on the yield of Dics. In all culture conditions, the estimated dose calculated based on the Dic frequency was equivalent to the absorbed dose of ex vivo X-ray-irradiated blood. CONCLUSION: While MI was affected by the blood culture type and the volume of cultured blood, Dic yield did not differ significantly between these conditions. These results could be used by relevant laboratories to optimize MI in certain circumstances.

Mode of Atmospheric Deposition in Forests Demonstrates Notable Differences in Initial Radiocesium Behavior.

The March 2011 Fukushima Dai-ichi Nuclear Power Plant accident in Japan released 520 PBq of radionuclides compared to a total release of 5300 PBq from the Chornobyl Nuclear Power Plant accident. Both nuclear accidents resulted in deposition of radiocesium throughout the northern hemisphere, and a plethora of studies have been performed regarding radiocesium (137Cs) behavior. However, few studies have assessed the impact of precipitation on 137Cs deposition in forests. Wide-scale environmental measurements from 2011 and 2016 were used to determine the differences in 137Cs deposition because of precipitation following the Fukushima accident. In areas where wet deposition processes were dominant, dense forests generally had lower ambient dose rates and levels of contamination on forest floors than other stands with fewer stems per hectare in 2011. Similar tendencies were not observed in areas that were primarily subject to dry deposition nor were any trends observed in 2016. 137Cs was retained in dense forest canopies for an extended period regardless of the deposition mode. Additionally, it was found that the initial retention of radionuclides by forest canopies is in general higher for areas with predominantly dry deposition. Incorporation of radiocesium into wood tissues was the same for both wet and dry deposition.

Simultaneous brain cell type and lineage determined by scRNA-seq reveals stereotyped cortical development.

Mutations are acquired frequently, such that each cell's genome inscribes its history of cell divisions. Common genomic alterations involve loss of heterozygosity (LOH). LOH accumulates throughout the genome, offering large encoding capacity for inferring cell lineage. Using only single-cell RNA sequencing (scRNA-seq) of mouse brain cells, we found that LOH events spanning multiple genes are revealed as tracts of monoallelically expressed, constitutionally heterozygous single-nucleotide variants (SNVs). We simultaneously inferred cell lineage and marked developmental time points based on X chromosome inactivation and the total number of LOH events while identifying cell types from gene expression patterns. Our results are consistent with progenitor cells giving rise to multiple cortical cell types through stereotyped expansion and distinct waves of neurogenesis. This type of retrospective analysis could be incorporated into scRNA-seq pipelines and, compared with experimental approaches for determining lineage in model organisms, is applicable where genetic engineering is prohibited, such as humans.

Radiocesium accumulation and germline mutations in chronically exposed wild boar from Fukushima, with radiation doses to human consumers of contaminated meat.

Genetic effects and radioactive contamination of large mammals, including wild boar (Sus scrofa), have been studied in Japan because of dispersal of radionuclides from the Fukushima Dai-ichi Nuclear Power Plant in 2011. Such studies have generally demonstrated a declining trend in measured radiocesium body burdens in wildlife. Estimating radiation exposure to wildlife is important to understand possible long-term impacts. Here, radiation exposure was evaluated in 307 wild boar inhabiting radioactively contaminated areas (50-8000 kBq m-2) in Fukushima Prefecture from 2016 to 2019, and genetic markers were examined to assess possible germline mutations caused by chronic radiation exposures to several generations of wild boar. Internal Cs activity concentrations in boar remained high in areas near the power plant with the highest concentration of 54 kBq kg-1 measured in 2019. Total dose rates to wild boar ranged from 0.02 to 36 µGy h-1, which was primarily attributed to external radiation exposure, and dose rates to the maximally exposed animals were above the generic no-effects benchmark of 10 µGy h-1. Using the estimated age of each animal, lifetime radiation doses ranged from <0.1 mGy to 700 mGy. Despite chronic exposures, the genetic analyses showed no significant accumulation of mutation events. Because wild boar is an occasional human dietary item in Japan, effective dose to humans from ingesting contaminated wild boar meat was calculated. Hypothetical consumption of contaminated wild boar meat from radioactively contaminated areas in Fukushima, at the per capita pork consumption rate (12.9 kg y-1), would result in an average effective annual dose of 0.9 mSv y-1, which is below the annual ingestion limit of 1 mSv y-1. Additionally, a consumption rate of about 1.4 kg y-1 of the most contaminated meat in this study would not exceed annual ingestion limits.

Deep Fractional Max Pooling Neural Network for COVID-19 Recognition.

Aim: Coronavirus disease 2019 (COVID-19) is a form of disease triggered by a new strain of coronavirus. This paper proposes a novel model termed "deep fractional max pooling neural network (DFMPNN)" to diagnose COVID-19 more efficiently. Methods: This 12-layer DFMPNN replaces max pooling (MP) and average pooling (AP) in ordinary neural networks with the help of a novel pooling method called "fractional max-pooling" (FMP). In addition, multiple-way data augmentation (DA) is employed to reduce overfitting. Model averaging (MA) is used to reduce randomness. Results: We ran our algorithm on a four-category dataset that contained COVID-19, community-acquired pneumonia, secondary pulmonary tuberculosis (SPT), and healthy control (HC). The 10 runs on the test set show that the micro-averaged F1 (MAF) score of our DFMPNN is 95.88%. Discussions: This proposed DFMPNN is superior to 10 state-of-the-art models. Besides, FMP outperforms traditional MP, AP, and L2-norm pooling (L2P).

Introgression dynamics from invasive pigs into wild boar following the March 2011 natural and anthropogenic disasters at Fukushima.

Natural and anthropogenic disasters have the capability to cause sudden extrinsic environmental changes and long-lasting perturbations including invasive species, species expansion and influence evolution as selective pressures force adaption. Such disasters occurred on 11 March 2011, in Fukushima, Japan, when an earthquake, tsunami and meltdown of a nuclear power plant all drastically reformed anthropogenic land use. Using genetic data, we demonstrate how wild boar (Sus scrofa leucomystax) have persevered against these environmental changes, including an invasion of escaped domestic pigs (Sus scrofa domesticus). Concurrently, we show evidence of successful hybridization between pigs and native wild boar in this area; however in future offspring, the pig legacy has been diluted through time. We speculate that the range expansion dynamics inhibit long-term introgression and introgressed alleles will continue to decrease at each generation while only maternally inherited organelles will persist. Using the gene flow data among wild boar, we assume that offspring from hybrid lineages will continue dispersal north at low frequencies as climates warm. We conclude that future risks for wild boar in this area include intraspecies competition, revitalization of human-related disruptions and disease outbreaks.

Evaluation of DNA damage and stress in wildlife chronically exposed to low-dose, low-dose rate radiation from the Fukushima Dai-ichi Nuclear Power Plant accident.

The health effects associated with chronic low-dose, low-dose rate (LD-LDR) exposures to environmental radiation are uncertain. All dose-effect studies conducted outside controlled laboratory conditions are challenged by inherent complexities of ecological systems and difficulties quantifying dose to free-ranging organisms in natural environments. Consequently, the effects of chronic LD-LDR radiation exposures on wildlife health remain poorly understood and much debated. Here, samples from wild boar (Sus scrofa leucomystax) and rat snakes (Elaphe spp.) were collected between 2016 and 2018 across a gradient of radiation exposures in Fukushima, Japan. In vivo biomarkers of DNA damage and stress were evaluated as a function of multiple measurements of radiation dose. Specifically, we assessed frequencies of dicentric chromosomes (Telomere-Centromere Fluorescence in situ Hybridization: TC-FISH), telomere length (Telo-FISH, qPCR), and cortisol hormone levels (Enzyme Immunoassay: EIA) in wild boar, and telomere length (qPCR) in snakes. These biological parameters were then correlated to robust calculations of radiation dose rate at the time of capture and plausible upper bound lifetime dose, both of which incorporated internal and external dose. No significant relationships were observed between dicentric chromosome frequencies or telomere length and dose rate at capture or lifetime dose (p value range: 0.20-0.97). Radiation exposure significantly associated only with cortisol, where lower concentrations were associated with higher dose rates (r2 = 0.58; p < 0.0001), a relationship that was likely due to other (unmeasured) factors. Our results suggest that wild boar and snakes chronically exposed to LD-LDR radiation sufficient to prohibit human occupancy were not experiencing significant adverse health effects as assessed by biomarkers of DNA damage and stress.

Restoring RUNX1 deficiency in RUNX1 familial platelet disorder by inhibiting its degradation.

RUNX1 familial platelet disorder (RUNX1-FPD) is an autosomal dominant disorder caused by a monoallelic mutation of RUNX1, initially resulting in approximately half-normal RUNX1 activity. Clinical features include thrombocytopenia, platelet functional defects, and a predisposition to leukemia. RUNX1 is rapidly degraded through the ubiquitin-proteasome pathway. Moreover, it may autoregulate its expression. A predicted kinetic property of autoregulatory circuits is that transient perturbations of steady-state levels result in continued maintenance of expression at adjusted levels, even after inhibitors of degradation or inducers of transcription are withdrawn, suggesting that transient inhibition of RUNX1 degradation may have prolonged effects. We hypothesized that pharmacological inhibition of RUNX1 protein degradation could normalize RUNX1 protein levels, restore the number of platelets and their function, and potentially delay or prevent malignant transformation. In this study, we evaluated cell lines, induced pluripotent stem cells derived from patients with RUNX1-FPD, RUNX1-FPD primary bone marrow cells, and acute myeloid leukemia blood cells from patients with RUNX1 mutations. The results showed that, in some circumstances, transient expression of exogenous RUNX1 or inhibition of steps leading to RUNX1 ubiquitylation and proteasomal degradation restored RUNX1 levels, thereby advancing megakaryocytic differentiation in vitro. Thus, drugs retarding RUNX1 proteolytic degradation may represent a therapeutic avenue for treating bleeding complications and preventing leukemia in RUNX1-FPD.

Radiocesium concentration ratios and radiation dose to wild rodents in Fukushima Prefecture.

Radiocesium was dispersed from the Fukushima Dai-ichi disaster in March 2011, causing comparatively high radioactive contamination in nearby environments. Radionuclide concentrations in wild rodents (Apodemus argenteus, and Apodemus speciosus) within these areas were monitored from 2012 to 2016. However, whole-organism to soil transfer parameters (i.e., concentration ratio, CRwo-soil) for wild rodents at Fukushima were not determined and hence were lacking from the international transfer databases. We augmented the 2012-2016 data by collecting soil activity concentrations (Bq kg-1, dry mass) from five rodent sampling sites in Fukushima Prefecture, and developed corresponding CRwo-soil values for radiocesium (134Cs and 137Cs) based on rodent radioactivity concentrations (Bq kg-1, fresh mass). The CRwo-soil were added to the Wildlife Transfer Database (WTD; http://www.wildlifetransferdatabase.org/), supporting the development of the International Commission on Radiological Protection's (ICRP) environmental protection framework, and increasing the WTD from 84 to 477 entries for cesium and Muridae ('Reference Rat'). Significant variation occurred in CRwo-soil values between study sites within Fukushima Prefecture. The geometric mean CRwo-soil, in this paper, was higher than that reported for Muridae species for Chernobyl. Radiocaesium absorbed dose rates were also estimated for wild rodents inhabiting the five Fukushima study sites and ranged from 1.3 to 33 µGy h-1. Absorbed dose rates decreased by a factor of two from 2012 to 2016. Dose rates in highly contaminated areas were within the ICRP derived consideration reference level for Reference Rat (0.1-1 mGy d-1), suggesting the possible occurrence of deleterious effects and need for radiological effect studies in the Fukushima area.

Differentiating Fukushima and Nagasaki plutonium from global fallout using 241Pu/239Pu atom ratios: Pu vs. Cs uptake and dose to biota.

Plutonium (Pu) has been released in Japan by two very different types of nuclear events - the 2011 Fukushima accident and the 1945 detonation of a Pu-core weapon at Nagasaki. Here we report on the use of Accelerator Mass Spectrometry (AMS) methods to distinguish the FDNPP-accident and Nagasaki-detonation Pu from worldwide fallout in soils and biota. The FDNPP-Pu was distinct in local environmental samples through the use of highly sensitive 241Pu/239Pu atom ratios. In contrast, other typically-used Pu measures (240Pu/239Pu atom ratios, activity concentrations) did not distinguish the FDNPP Pu from background in most 2016 environmental samples. Results indicate the accident contributed new Pu of ~0.4%-2% in the 0-5 cm soils, ~0.3%-3% in earthworms, and ~1%-10% in wild boar near the FDNPP. The uptake of Pu in the boar appears to be relatively uninfluenced by the glassy particle forms of fallout near the FDNPP, whereas the 134,137Cs uptake appears to be highly influenced. Near Nagasaki, the lasting legacy of Pu is greater with high percentages of Pu sourced from the 1945 detonation (~93% soils, ~88% earthworm, ~96% boar). The Pu at Nagasaki contrasts with that from the FDNPP in having proportionately higher 239Pu and was distinguished by both 240Pu/239Pu and 241Pu/239Pu atom ratios. However, compared with the contamination near the Chernobyl accident site, the Pu amounts at all study sites in Japan are orders of magnitude lower. The dose rates from Pu to organisms in the FDNPP and Nagasaki areas, as well as to human consumers of wild boar meat, have been only slightly elevated above background. Our data demonstrate the greater sensitivity of 241Pu/239Pu atom ratios in tracing Pu from nuclear releases and suggest that the Nagasaki-detonation Pu will be distinguishable in the environment for much longer than the FDNPP-accident Pu.

Radiocesium concentrations and GPS-coupled dosimetry in Fukushima snakes.

One of the largest releases of radioactive contamination in history occurred at Japan's Fukushima Daiichi Nuclear Power Plant (FDNPP). Although the accident happened in 2011, questions still persist regarding its ecological impacts. For example, relatively little is known about radiocesium accumulation in snakes, despite their high trophic status, limited home range sizes, and close association with soil where many radionuclides accumulate. This study presents one of the most comprehensive radioecological studies of snakes published to date using a combination of whole-body radiocesium analyses, GPS transmitters, and optically stimulated luminescence (OSL) dosimeters. The objectives were to: 1) quantify whole-body radiocesium activity concentrations and internal dose rates among several common species of snakes within and around the Fukushima Exclusion Zone (FEZ), 2) determine effects of species, sex, and body size on radiocesium activity concentrations, 3) measure external dose rates using GPS-coupled dosimeters deployed on free-ranging snakes, 4) compare field-derived empirical dose rates to those generated by computer simulation software (i.e., the ERICA tool), and 5) determine if incorporating snake behavior into computer models improve simulated estimates of external dose. Whole-body radiocesium levels for snakes were highly variable among individuals (16 to 25,000 Bq/kg, FW), but were influenced more by levels of local contamination than species, sex, or size. Doses recorded by OSL dosimeters on snakes, as well as modeling in ERICA, suggest that individual movements and behavior have a substantial influence on dose rates to snakes. However, dose estimates produced with ERICA were comparable to dose received by tracked snakes. The average external plus internal dose rate for snakes captured in the FEZ was 3.6-3.9 µGy/h, with external dose contributing 80% to the total. Further research regarding reptile-specific benchmark dose rates would improve risk assessment for reptiles in radiologically contaminated areas.

Effective Half-life of 134Cs and 137Cs in Fukushima Prefecture When Compared to Theoretical Decay Models.

On 11 March 2011, a 9.0 magnitude earthquake struck the Tohoku region of Japan. The earthquake caused a 15 m tsunami that bombarded the east coast of the island nation. Among the losses was the damage to the Fukushima Daiichi nuclear reactor that lost onsite power and was unable to cool the reactor cores. The reactors melted down and released a plume of radionuclides into the environment. Radiocesiums (Cs and Cs) are the long-lived radionuclides of concern that were deposited along the plume and were distributed on the soil. Radiological decay models are typically used to determine the reduction in external radiation dose over time. However, these radiological decay models do not take into account physical removal by wind and water erosion, or sedimentation in soil outside expected depths. Thirty-five fixed dose-rate monitors were used to record dose rates at 1 mo intervals from the time of installation in Fukushima Prefecture in April 2012 until December 2018 and were used to estimate the effective half-life for radiocesium contamination based on external radiation dose rates. The effective half-life of cesium in the environment was calculated to be 3.2 ± 0.5 y, compared to a theoretical half-life of 7.8 y.

Author Correction: Mating of escaped domestic pigs with wild boar and possibility of their offspring migration after the Fukushima Daiichi Nuclear Power Plant accident.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Mating of escaped domestic pigs with wild boar and possibility of their offspring migration after the Fukushima Daiichi Nuclear Power Plant accident.

The 2011 Tohoku earthquake drastically changed human activities in some regions of Fukushima Prefecture, Japan. The subsequent tsunami damage and radioactive pollution from the Fukushima Daiichi nuclear power plant resulted in the evacuation of humans, and abandonment of agricultural lands, allowing population expansion of wildlife into areas formally inhabited by domesticated livestock. Unintentional escape of domesticated pigs into wildlife inhabited environments also occurred. In this study, we tested the possibility of introgression between wild boar and domesticated pigs in Fukushima and neighboring prefectures. We analyzed mitochondrial DNA sequences of 338 wild boar collected from populations in the Tohoku region between 2006 and 2018. Although most boar exhibited Asian boar mitochondrial haplotypes, 18 boar, phenotypically identified as wild boar, had a European domesticated pig haplotype. Frequencies of this haplotype have remained stable since first detection in 2015. This result infers ongoing genetic pollution in wild boar populations from released domesticated pigs. In 2018, this haplotype was detected outside of evacuated areas, suggesting migration and successful adaptation. The natural and anthropocentric disasters at Fukushima gave us the rare opportunity to study introgression processes of domestic genes into populations of wild boar. The present findings suggest a need for additional genetic monitoring to document the dispersal of domestic genes within wild boar stock.

A comparison of methods to derive aggregated transfer factors using wild boar data from the Fukushima Prefecture.

Aggregated transfer factors (Tag; m2 kg-1) are often used to predict radionuclide activity concentrations in biota (Bq kg-1) from soil contamination levels (Bq m-2). Inherently large uncertainties in Tag values severely limit their predictive power. Many published Tag values have been derived from radionuclide deposition onto soil following weapons fallout, or the accidents at Chernobyl and Fukushima. In many cases the soil data used to derive a Tag value were collected for other purposes, and the spatial resolution of the soil data is much less than that of the biota data to which it is paired. We hypothesized that this disassociation and imprecision in paring deposition density and biota data may contribute to the large variations observed in Tag values. We tested the hypothesis by deriving Tag values for Japanese wild boar in two ways. One method used paired deposition density-biota contamination levels, with the soil data collected from each boar trap site. The second method used a soil radioactivity density map, of relatively low spatial resolution, generated by the Japanese government agency MEXT for fallout from the Fukushima accident. We hypothesized that Tag values derived from the method using paired deposition density-wild boar data would have less variation. Initial statistical test suggested significant differences in the predictive power of the two methods. However, removal of suspected outliers in the MEXT data set decreased the statistical differences and indicated that collecting 137Cs soil deposition density measurements in the field did not reduce the large variation in our Tag values. More importantly, both methods revealed that soil contamination levels are a poor predictor of radiocesium concentrations in boar (r2 < 0.23). The inadequacies of Tag to predict wild boar 137Cs concentrations is an ominous indication of the lack of applicability of the Tag model as a rigorous research parameter. Tag values are best suited for their original intended purpose: upper tier, screening level computations. Further studies on how to reduce uncertainty when predicting 137Cs concentrations in biota are needed to thoroughly understand the transfer of radiocesium within the environment.

Activating PAX gene family paralogs to complement PAX5 leukemia driver mutations.

PAX5, one of nine members of the mammalian paired box (PAX) family of transcription factors, plays an important role in B cell development. Approximately one-third of individuals with pre-B acute lymphoblastic leukemia (ALL) acquire heterozygous inactivating mutations of PAX5 in malignant cells, and heterozygous germline loss-of-function PAX5 mutations cause autosomal dominant predisposition to ALL. At least in mice, Pax5 is required for pre-B cell maturation, and leukemic remission occurs when Pax5 expression is restored in a Pax5-deficient mouse model of ALL. Together, these observations indicate that PAX5 deficiency reversibly drives leukemogenesis. PAX5 and its two most closely related paralogs, PAX2 and PAX8, which are not mutated in ALL, exhibit overlapping expression and function redundantly during embryonic development. However, PAX5 alone is expressed in lymphocytes, while PAX2 and PAX8 are predominantly specific to kidney and thyroid, respectively. We show that forced expression of PAX2 or PAX8 complements PAX5 loss-of-function mutation in ALL cells as determined by modulation of PAX5 target genes, restoration of immunophenotypic and morphological differentiation, and, ultimately, reduction of replicative potential. Activation of PAX5 paralogs, PAX2 or PAX8, ordinarily silenced in lymphocytes, may therefore represent a novel approach for treating PAX5-deficient ALL. In pursuit of this strategy, we took advantage of the fact that, in kidney, PAX2 is upregulated by extracellular hyperosmolarity. We found that hyperosmolarity, at potentially clinically achievable levels, transcriptionally activates endogenous PAX2 in ALL cells via a mechanism dependent on NFAT5, a transcription factor coordinating response to hyperosmolarity. We also found that hyperosmolarity upregulates residual wild type PAX5 expression in ALL cells and modulates gene expression, including in PAX5-mutant primary ALL cells. These findings specifically demonstrate that osmosensing pathways may represent a new therapeutic target for ALL and more broadly point toward the possibility of using gene paralogs to rescue mutations driving cancer and other diseases.