浮遊性有孔虫の光共生の発展と終焉 : 光合成生理と安定同位体シグナル

早大学位記番号:新7149早稲田大

The effect of experience on parental role division in Ryukyu Scops Owl Otus elegans

Parental role division is common among monogamous birds. Among raptors, males typically expend more effort to feed their chicks than do females, yet few studies have focused on how each pair establishes this role division. Therefore, in this study we examined the mechanism of role division in the Ryukyu Scops Owls Otus elegans on Minami-daito Island. Pairs of this species typically remain together and use the same nest over several years, so there is a possibility that their role division improves with experience over time. To clarify this, we studied the feeding frequency and territorial usage of individuals. Males fed their chicks more frequently than females, and experienced individuals using the same nests fed their chicks more than inexperienced individuals. On comparing experienced and inexperienced pairs, we found that experienced individuals hunted closer to the nest than inexperienced individuals. Furthermore, the home ranges of the males and females of experienced pairs, overlapped less than those of inexperienced pairs. Experience of using a nest site in consecutive years may allow such individual behavioural differences to develop and be involved in role division in parental care

Fasting and Glucagon Stimulate Gene Expression of Pyruvate Dehydrogenase Kinase 4 in Chickens

The excessive accumulation of body fat has become a serious problem in the broiler industry. However, the molecular mechanisms underlying the regulation of lipid metabolism-related genes in broiler chickens are not fully understood. In the present study, we investigated the role of glucagon on the expression of lipid metabolism-related genes in chicken white adipose tissue (WAT). Four hours of fasting significantly increased plasma levels of free fatty acid in broiler chickens. The mRNA levels of adipose triglyceride lipase (ATGL) and pyruvate dehydrogenase kinase 4 (PDK4) in abdominal WAT significantly increased by fasting, whereas the mRNA levels of diacylglycerol O-acyltransferase homolog 2 (DGAT2) and peroxisome proliferator-activated receptor-γ (PPARγ) significantly decreased. The results suggest that fasting stimulates lipolysis and suppresses adipogenesis and re-esterification of TG in chicken WAT. Glucagon significantly increased the mRNA levels of PDK4 in chicken primary adipocytes, whereas there were no significant changes in the mRNA levels of ATGL, DGAT2, and PPARγ. Our findings suggest that glucagon upregulates PDK4 expression and may stimulate lipolysis without affecting the expression of ATGL in chicken WAT

Data from: Exploring photosymbiotic ecology of planktic foraminifers from chamber-by-chamber isotopic history of individual foraminifers

Evolution of photosymbiotic ecology is an important adaptation for planktic foraminifers that enhances the ecological advantage of living in oligotrophic oceans. Therefore, detecting photosymbiotic ecology in fossil species is one of the keys to understanding the paleobiodiversity dynamics of planktic foraminifers. Because foraminiferal tests record the ontogenetic history of ecological information in geochemical signatures, analyzing individual geochemical profiles with growth can reveal a species’ ecology. This study examined chamber-by-chamber stable isotopes (δ13C and δ18O) of foraminiferal individuals to identify photosymbiotic signals. We observed an ontogenetic δ13C increase of up to 2.4‰, accompanied by relatively stable, negative δ18O, in the symbiotic species Globigerinoides conglobatus and Globigerinoides sacculifer. In contrast, δ13C and δ18O showed significant positive correlation during ontogeny in the asymbiotic species Globorotalia truncatulinoides. These two ecological groups produce contrasting isotopic profiles, thereby allowing us to use our ontogenetic isotopic analyses of individual specimens to identify algal photosymbiosis in fossil foraminifers. The chamber-by-chamber isotope analyses with individual ontogeny have great advantages in analyzing rare species because only one individual is required to describe ontogenetic isotopic history. In addition to photosymbiotic identification, our methods hold great potential to provide new insight into species paleoecological studies such as the ontogenetic history of calcification depth