近江 俊徳

We examined the conception rate of wild Japanese monkeys (Macaca fuscata) in Fukushima City that were exposed to radiation as a result of the Fukushima Daiichi Nuclear Power Plant accident in March 2011. The conception rate in the year of delivery from 2009 to 2022 was estimated by dissecting individuals that were euthanized by the government for population control as a countermeasure against crop damage. To evaluate the effects of exposure, the cumulative exposure dose for each individual was calculated using the concentration of radiocesium deposited in the soil at the capture site and the concentration of radiocesium in muscle estimated from the aggregated transfer factor. There were no significant differences in conception rates across all age classes over time. In terms of conception rates by age class, there was a significant decrease post-exposure compared with pre-exposure in the age class ≥ 8 years, but no significant differences in the age class 5-7 years. The non-ovulation rate did not significantly differ between the pre- and post-exposure periods for any age class. Body fat index, which can affect fertility, was compared between the pre- and post-exposure periods, and no significant differences were found in either age class. In contrast, the median total cumulative exposure (cumulative internal exposure + cumulative external exposure) was significantly higher in the age class ≥ 8 years compared with the age class 5-7 years. These results suggest that the total cumulative exposure dose may be one of the reasons for the lower conception rate in the post-exposure period among the age class ≥ 8 years.

Wild Japanese monkeys (Macaca fuscata) were exposed to radiation after the Fukushima Daiichi nuclear accident in 2011. To clarify the biological effects of radiation exposure on their fetal growth, pregnant monkeys and their fetuses were analyzed. These animals were collected between 2008 and 2020 (before and after the accident in 2011) living in Fukushima City, approximately 70 km from the nuclear power plant. Multiple regression analyses were conducted with fetal body weight (FBW) and fetal head circumference (FHS) as objective variables, and maternal and fetal factors as explanatory variables. The maternal factors were relative exposure dose rate (REDR), age, body weight, body length, fat index, and parity. The fetal factors were crown ramp length (CRL) and sex. Multiple regression analyses showed that FBR and FHS growth were positively associated with CRL, maternal body length, and negatively associated with REDR. Since the relative growth of FBR and FHS to CRL decreased with increasing REDR, radiation exposure due to the nuclear accident may have contributed to the delayed fetal growth observed in Japanese monkeys.

Over the 10 years immediately after the Fukushima Daiichi nuclear accident, we measured the changes in the muscle 137Cs concentration (Bq/kg) of wild Japanese monkeys living in Fukushima City, which is located approximately 70 km from the Fukushima Daiichi Nuclear Power Plant. The muscle137Csconcentration, which was observed at a maximum of 13,500 Bq/kg immediately after the accident, had decreased to several hundred Bq/kg 10 years later. The muscle 137Cs concentration was significantly related to the soil contamination levels (10,000-30,000, 30,000-60,000, 60,000-100,000, and 100,000-300,000 Bq/m2), sex, age class (immature, mature), body weight (> 5000 g, 5000-10,000 g, < 10,000 g), and seasons (the cold period from December to April, the warm period from May to November).The value of muscle 137Cs concentration and the aggregated transfer factor (Tag: calculated by dividing muscle 137Cs concentration [Bq/kg] by soil 137Cs deposition density at the capture site [Bq/m2]) apparently decreased with time for several years. However, post hoc pairwise comparisons showed no difference from 2017 to 2020, and the accumulation of 137Cs in muscle may continue for some time.

The feline AB blood group system (blood types A, B, and AB) encoding the cytidine monophosphate-N-acetylneuraminic acid hydroxylase (<italic>CMAH</italic>) gene is the most significant in transfusion medicine and hemolysis of the newborn for cats. Blood typing and cross-matching in pre-transfusion testing are crucial to determining blood compatibility and thus prevent hemolytic transfusion reactions. We here performed serological and genetic investigations to characterize blood samples from cats with discordant results for card agglutination (CARD) and the alloantibody agglutination test for blood typing in two cats (subjects K and R). Subject K showed incompatible cross-matching in pre-transfusion testing. Red blood cells from subjects K and R determined blood type B from the CARD method showed blood type AB by alloanti-A and alloanti-B antibodies in agglutination testing. Genomic DNA sequencing of the coding region (exons 1a to 14) for the cat <italic>CMAH</italic> gene showed that subject K had four mutations with heterozygosity at c.139C&amp;gt;T, c.179G&amp;gt;T, c.327A&amp;gt;C, and c.364C&amp;gt;T. Similarly, the <italic>CMAH</italic> gene of subject R carried six mutations with heterozygosity at c.142G&amp;gt;A, c.187A&amp;gt;G, c.268T&amp;gt;A, c.327A&amp;gt;C, c.773G&amp;gt;A and c.1603G&amp;gt;A, representing a new diplotype including a novel synonymous single nucleotide polymorphism (SNP) in exon 7 (c.773 G&amp;gt;A: Arg258Gln). The <italic>CMAH</italic> diplotype in subjects K and R was different from major diplotype in blood type B cats. This study is the first to report <italic>CMAH</italic> variants in cats with discordant blood types between CARD and TUBE methods. These results could assist in the classification of feline AB blood types for transfusion medicine to avoid blood incompatibilities.

Aim: Understanding patterns and processes of geographic genetic variation within and among closely related species is the essence of phylogeography. Japanese macaques, also called snow monkeys, have been extensively studied, particularly in the fields of sociobiology, ecology and experimental biology; however, our knowledge of their evolutionary history is relatively limited. In this study we aimed to elucidate the geographic patterns of genetic variation in Japanese macaques and the processes that underlie them. Location: Japan. Taxa: Japanese macaque, Macaca fuscata; rhesus macaque, M. mulatta; Taiwanese macaque, M. cyclopis. Methods: Double-digest restriction site-associated DNA (RAD) sequencing was used to identify genome-wide single nucleotide variants. We used fineRADstructure, ADMIXTURE and principal component analyses to estimate the genetic population structure. Phylogenetic relationships were then inferred based on neighbour-net, neighbour-joining, maximum likelihood and SVDquartets algorithms. We assessed gene flow using demographic inference and ABBA-BABA tests, and estimated past distributions during the Last Glacial Maximum (LGM) using ecological niche modelling. Results: Japanese macaques show a sister group relationship with a clade comprising Chinese rhesus, Indian rhesus and Taiwanese macaques. Japanese macaques comprise major north-eastern and south-western clades, with a boundary located near central Japan, and gene flow between the north-eastern and south-western lineages was detected. Refugia during the LGM were estimated to be distributed in limited areas along the south coasts of the Japanese archipelago. Main conclusions: Phylogeographic variation of Japanese macaques is likely due mainly to northeast–southwest divergence, which resulted from withdrawal into refugia during the glacial period, and subsequent gene flow.