Inferring prey size variation from mandible acceleration in northern elephant seals

Prey size is an important factor for predators as it affects prey quality (energy content) and hence total energy gain. However, it remains challenging to obtain information about prey size from free‐ranging marine predators. Here, we developed a method that estimates prey size using mandible acceleration in captive northern elephant seals and then applied it to 34 free‐ranging seals. In captive seals, the number of feeding‐related acceleration signals were positively related to prey size category (<15 cm). In free‐ranging seals, smaller number of acceleration signals occurred frequently in both mesopelagic (200–1,000 m) and bathypelagic layers (>1,000 m), suggesting that seals foraged mainly on smaller prey (possibly <15 cm). However, the quantity of larger acceleration signals increased in the bathypelagic layers, suggesting that seals were more likely to forage on larger prey (>15 cm) at deeper depths. These results suggest that seals might compensate for higher energetic costs of deeper‐diving by targeting larger prey. Although our study has practical limitations (e.g., calibrating prey size in captive conditions), our method allows concurrent inference of prey size and foraging behavior, being potentially useful to investigate how predators adjust their behavior in response to the changes in the foraging environment.     

Phylogenetic Analysis of Bacteria Preserved in a Permafrost Ice Wedge for 25,000 Years

Phylogenetic analysis of bacteria preserved within an ice wedge from the Fox permafrost tunnel was undertaken by cultivation and molecular techniques. The radiocarbon age of the ice wedge was determined. Our results suggest that the bacteria in the ice wedge adapted to the frozen conditions have survived for 25,000 years.     

模拟大气氮沉降对中国森林生态系统影响的研究进展

人类活动加剧了活性氮的生产和排放,并导致氮沉降日益增加并全球化。目前,人类活动对全球氮循环的干扰已经超出了地球系统安全运行的界限。中国已成为全球氮沉降的高发区域,高氮沉降已经威胁到生态系统的健康和安全,并成为生态文明建设过程中亟待理清和解决的热点问题。对国际上和中国森林生态系统模拟氮沉降研究的概况进行了综述,并从生物学和非生物学两大过程重点阐述模拟氮沉降增加对中国主要森林生态系统影响的研究进展。中国自2000年以后才开始重视大气氮沉降产生的生态环境问题,中国科学院华南植物园在国内森林生态系统模拟氮沉降试验研究上做出了开创性的贡献。模拟氮沉降研究表明,持续高氮输入将会显著改变森林生态系统的结构和功能,并威胁生态系统的健康发展,特别是处于氮沉降热点区域的中国中南部。森林生态系统的氮沉降效应依赖于系统的氮状态、土地利用历史、气候特征、林型和林龄等。最后,对未来的研究提出了一些建议,包括加强长期跟踪研究和不同气候带站点之间的联网研究,特别是在森林生态系统对长期氮沉降响应与适应的过程机制、地下碳氮吸存潜力研究、以及与其他全球变化因子的耦合研究等方面,以期为森林生态系统的可持续发展提供理论基础和管理依据。     

Dependence of the timing system regulating the onset of gastrulation on cytoplasmic, but not nuclear, activities in the Xenopus embryo

This study examines the properties of the timer that regulates the onset of gastrulation in the Xenopus embryo. Pre-gastrulation embryos were exposed to aphidicolin, vinblastine, 6-dimethylaminopurine (6-DMAP) or urethane. Embryos exposed to aphidicolin or vinblastine for 0.5-2 h before the presumptive onset of gastrulation, began gastrulation at the same time as control embryos. However, those exposed to 6-DMAP or urethane commenced gastrulation significantly later than controls. In 6-DMAP- and urethane-treated embryos, the onset of gastrulation was retarded by approximately 25% and 120%, respectively. 6-DMAP and urethane, but not vinblastine, also lowered the rate of nuclear doubling by 30% and 120%, respectively, in late-blastula to early-gastrula embryos. 6-DMAP and urethane also lowered the rate of cleavage and cleavage-relevant cytoplasmic cycling by 30% and 80%, respectively, in cleavage-stage embryos. We propose that cytoplasmic activities that can be retarded by 6-DMAP and urethane, but not aphidicolin or vinblastine, may be responsible for regulating the onset of gastrulation in Xenopus embryos.     

Association of habitual dietary intake with morningness-eveningness and rotating shift work in Japanese female nurses

Rotating shift workers are associated with imbalanced dietary intakes. Rotating shift workers and dietary intakes in adults who do not engage in night work have also been shown to be associated with chronotype. However, no studies have examined associations between morningness-eveningness (i.e., the degree to which people prefer to be active in the morning or the evening), rotating shift work and dietary intakes. Therefore, our first purpose was to elucidate the association between morningness-eveningness and habitual food group intakes in rotating shift workers. The second purpose was to elucidate the association of morningness-eveningness and rotating shift work with food group intakes, considering habitual sleep durations. Japanese nurses (1095 day workers and 1464 rotating shift workers) were studied using a self-administered questionnaire. The questionnaire covered habitual dietary intakes, morningness-eveningness and demographic characteristics of the participants. A Japanese version of the Morningness-Eveningness Questionnaire (MEQ) was used to measure self-rated morningness-eveningness. Dietary intakes over the previous 1 month were evaluated using a semi-quantitative food frequency questionnaire. Intakes of pulses, green/yellow vegetables, white vegetables, fruits, algae, eggs, confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) associated with the MEQ score in rotating shift workers. Among these food groups, intakes of green/yellow vegetables, white vegetables, fruits and algae were significantly (p < 0.05) lower in rotating shift workers than in day workers, and intakes of confectioneries/savory snacks and sugar-sweetened beverages were significantly (p < 0.05) higher in rotating shift workers than in day workers. Intakes of these food groups were also significantly (p < 0.05) associated with the MEQ score in day workers. In addition, the MEQ score was significantly (p < 0.05) lower in rotating shift workers than in day workers, indicating greater eveningness among rotating shift workers. Multivariate linear regression revealed that the MEQ scores were significantly (p < 0.05) associated with intakes of these food groups, while rotating shift work was associated only with confectioneries/savory snacks. These results suggest that morningness-eveningness is associated with unbalanced dietary intakes in rotating shift workers as well as day workers, which may partially explain associations between rotating shift work and unfavorable dietary intakes. These findings have important implications for the development of novel strategies for preventing poor health caused by imbalanced dietary intakes in rotating shift workers.     

Adjustment of Cell-Type Composition Minimizes Systematic Bias in Blood DNA Methylation Profiles Derived by DNA Collection Protocols

Differences in DNA collection protocols may be a potential confounder in epigenome-wide association studies (EWAS) using a large number of blood specimens from multiple biobanks and/or cohorts. Here we show that pre-analytical procedures involved in DNA collection can induce systematic bias in the DNA methylation profiles of blood cells that can be adjusted by cell-type composition variables. In Experiment 1, whole blood from 16 volunteers was collected to examine the effect of a 24 h storage period at 4°C on DNA methylation profiles as measured using the Infinium HumanMethylation450 BeadChip array. Our statistical analysis showed that the P-value distribution of more than 450,000 CpG sites was similar to the theoretical distribution (in quantile-quantile plot, λ = 1.03) when comparing two control replicates, which was remarkably deviated from the theoretical distribution (λ = 1.50) when comparing control and storage conditions. We then considered cell-type composition as a possible cause of the observed bias in DNA methylation profiles and found that the bias associated with the cold storage condition was largely decreased (λ_adjusted = 1.14) by taking into account a cell-type composition variable. As such, we compared four respective sample collection protocols used in large-scale Japanese biobanks or cohorts as well as two control replicates. Systematic biases in DNA methylation profiles were observed between control and three of four protocols without adjustment of cell-type composition (λ = 1.12–1.45) and no remarkable biases were seen after adjusting for cell-type composition in all four protocols (λ_adjusted = 1.00–1.17). These results revealed important implications for comparing DNA methylation profiles between blood specimens from different sources and may lead to discovery of disease-associated DNA methylation markers and the development of DNA methylation profile-based predictive risk models.     

Interpersonal Similarity between Body Movements in Face-To-Face Communication in Daily Life

Individuals are embedded in social networks in which they communicate with others in their daily lives. Because smooth face-to-face communication is the key to maintaining these networks, measuring the smoothness of such communication is an important issue. One indicator of smoothness is the similarity of the body movements of the two individuals concerned. A typical example noted in experimental environments is the interpersonal synchronization of body movements such as nods and gestures during smooth face-to-face communication. It should therefore be possible to estimate quantitatively the smoothness of face-to-face communication in social networks through measurement of the synchronization of body movements. However, this is difficult because social networks, which differ from disciplined experimental environments, are open environments for the face-to-face communication between two individuals. In such open environments, their body movements become complicated by various external factors and may follow unstable and nonuniform patterns. Nevertheless, we consider there to be some interaction during face-to-face communication that leads to the interpersonal synchronization of body movements, which can be seen through the interpersonal similarity of body movements. The present study aims to clarify such interaction in terms of body movements during daily face-to-face communication in real organizations of more than 100 people. We analyzed data on the frequency of body movement for each individual during face-to-face communication, as measured by a wearable sensor, and evaluated the degree of interpersonal similarity of body movements between two individuals as their frequency difference. Furthermore, we generated uncorrelated data by resampling the data gathered and compared these two data sets statistically to distinguish the effects of actual face-to-face communication from those of the activities accompanying the communication. Our results confirm an interpersonal similarity of body movements between two individuals in face-to-face communication, for all the organizations studied, and suggest that some body interaction is behind this similarity.     

Low‐frequency mechanical vibration induces apoptosis of A431 epidermoid carcinoma cells

Cancer research is increasingly focused on discovering strategies to induce cancer cell apoptosis without affecting surrounding normal cells. One potential biocompatible method is mechanical vibration, which has been developed as part of the emerging field of mechanomedicine. Previous studies of mechanical vibration have employed high‐frequency vibration, which damages healthy cells. In this study, we examined the effects of brief (1 h) low‐frequency (20 Hz) mechanical vibration on glucose consumption and survival (apoptosis, necrosis, HMGB1 release) of the human epidermoid carcinoma cell line A431. We found that apoptosis, but not necrosis, was significantly increased at 48 h after mechanical vibration compared with cells maintained in static culture. In keeping with this, extracellular release of HMGB1, a necrosis marker, was lower in cultures of A431 cells subjected to mechanical vibration compared with control cells. Glucose consumption was increased in the first 24 h after mechanical vibration but returned to control levels before the onset of apoptosis. Although the precise intracellular mechanisms by which low‐frequency mechanical vibration triggers apoptosis of A431 cells is unknown, these results suggest a possible role for metabolic pathways. Mechanical vibration may thus represent a novel application of mechanomedicine to cancer therapy.     

p27Kip1 enforces maintenance of quiescence in the mammalian ear and the pituitary gland

Comment on: Oesterle EC, et al. Cell Cycle 2011; 10:1237-48.