Continuous, rather than discrete, data on animal population are ideal for identifying the causal relationships driving population fluctuations. In this study, we reveal the effect of forest regeneration after logging on the habitat, food availability, and abundance of Japanese macaques over two decades, spanning the period from 2000 until 2019, based on a continuous population census conducted every year. Three vegetation types, covering an area of 7.5 km2, make up our study sites: primary forests, forests logged from 1984 until 1995 and then naturally regenerated (natural regeneration), and forests logged from 1975 until 1983 and then planted with cedars (plantation). In natural regeneration, both individual and total tree biomass increased, in particular naturally grown cedars. In plantation, the number of trees decreased and the total biomass did not change, mainly due to thinning (partial removal of planted cedars to harvest timber) in 2015. A state space model suggests that the relative fruit production in natural regeneration to that in the primary forest tended to be low after 2012, a condition brought about by cleaning cutting to remove non-cedar broad-leaved trees and shrubs in natural regeneration. An analysis of aerial photos detected an increase in naturally grown cedar patches in natural regeneration between 2009 and 2014. We also observed a population decrease of Japanese macaques in natural regeneration but not in primary and plantation forests. The state space model indicates that this decrease occurred in the first half of the study period, which was earlier than the replacement of cedar patches in natural regeneration. The high time resolution of our data refutes the simple sce-nario that macaques decreased their number in natural regeneration due to the reduced food availability there. The less frequent use of natural regeneration began as a stochastic event; i.e., the disappearance of multiple individuals from a group ranging there, and then the subsequent changes in the habitat reinforced this tendency.

Cadmium (Cd) and arsenic (As) pollution in paddy soil and their accumulation in rice (Oryza sativa) pose serious threats to human health. Rice internally detoxifies these toxic metal and metalloid to some extent, resulting in their accumulation within the edible parts. However, the mechanisms of Cd and As detoxification in rice have been poorly elucidated. Plants synthesize thiol-rich metal-chelating peptides, termed phytochelatins (PCs). We characterized rice PC synthase (PCS) and investigated its contribution to Cd and As tolerance in rice. We identified two PCS homolog genes, OsPCS1 and OsPCS2, in the rice genome. The expression of OsPCS1 was upregulated by As(III) stress in the roots but that of OsPCS2 was not significantly affected. The expression level of OsPCS2 was higher than that of OsPCS1 in the shoots and roots. Recombinant OsPCS1 and OsPCS2 proteins differed in their metal activation. OsPCS1 was more strongly activated by As(III) than by Cd; however, OsPCS2 was more strongly activated by Cd than by As(III). Genetically engineered plants having their OsPCS2 expression silenced via RNA interference (OsPCS2 RNAi) contained less PCs and more glutathione (GSH), a substrate of PC synthesis, than wild-type plants, although there was no significant difference in OsPCS1 RNAi plants. OsPCS2 RNAi plants were sensitive to As(III) stress, but Cd tolerance was little affected. On the other hand, treatment with buthionine sulfoximine, an inhibitor of GSH biosynthesis, significantly decreased Cd and As tolerance of rice seedlings. These findings indicate that OsPCS2 is a major isozyme controlling PC synthesis, and that PCs are important for As tolerance in rice. However, PC synthesis may make a smaller contribution to Cd tolerance in rice, and GSH plays crucial roles, not only as a substrate of PC synthesis.

We aimed to validate a method to identify age class and sex of sika deer (Cervus nippon), which defecate fecal pellets. We collected 42 and 54 fecal samples in Nara and Yakushima, respectively. Both pellet width and length were significantly larger for adults than juveniles (1 similar to 1.5 yrs). A discriminant model based on both width and length correctly assigned an age class for 92% of individuals in Nara and 98% in Yakushima. We genetically determined their sex based on the gel electrophoresis of two genes on sex chromosomes (SRY and ZFX/Y) amplified by PCR. For fresh feces, sex was not determined for 40% of the samples, but for the rest of the samples, sex was correctly assigned in almost all cases (28/29). However, sex was not determined in any of the samples that were analyzed at a half month or later after defecation. The proportion of young individuals could be estimated by the morphometry of fecal pellets, but the sex of the animals could not be confirmed.