Cell populations and morphogenetic movements underlying formation of the avian primitive streak and organizer

The cell populations and morphogenetic movements that contribute to the formation of the avian primitive streak and organizer-Hensen's node-are poorly understood. We labeled selected groups of cells with fluorescent dyes and then followed them over time during formation and progression of the primitive streak and formation of Hensen's node. We show that (1) the primitive streak arises from a localized population of epiblast cells spanning the caudal midline of Koller's sickle, with the mid-dorsal cells of the primitive streak arising from the midline of the epiblast overlying Koller's sickle and the deeper and more lateral primitive streak cells arising more laterally within the epiblast overlying the sickle, from an arch subtending about 30 degrees; (2) convergent extension movements of cells in the epiblast overlying Koller's sickle contribute to formation of the initial primitive streak; and (3) Hensen's node is derived from a mixture of cells originating both from the epiblast just rostral to the incipient (stage 2) primitive streak and later from the epiblast just rostral to the elongating (stage 3a/b) primitive streak, as well as from the rostral tip of the progressing streak itself. Collectively, these results provide new information on the formation of the avian primitive streak and organizer, increasing our understanding of these important events of early development of amniotes.     

Influence of “protective” symbionts throughout the different steps of an aphid–parasitoid interaction

Microbial associates are widespread in insects, some conferring a protection to their hosts against natural enemies like parasitoids. These protective symbionts may affect the infection success of the parasitoid by modifying behavioral defenses of their hosts, the development success of the parasitoid by conferring a resistance against it or by altering life-history traits of the emerging parasitoids. Here, we assessed the effects of different protective bacterial symbionts on the entire sequence of the host-parasitoid interaction (i.e., from parasitoid attack to offspring emergence) between the pea aphid, Acyrthosiphon pisum, and its main parasitoid, Aphidius ervi and their impacts on the life-history traits of the emerging parasitoids. To test whether symbiont-mediated phenotypes were general or specific to particular aphid–symbiont associations, we considered several aphid lineages, each harboring a different strain of either Hamiltonella defensa or Regiella insecticola, two protective symbionts commonly found in aphids. We found that symbiont species and strains had a weak effect on the ability of aphids to defend themselves against the parasitic wasps during the attack and a strong effect on aphid resistance against parasitoid development. While parasitism resistance was mainly determined by symbionts, their effects on host defensive behaviors varied largely from one aphid–symbiont association to another. Also, the symbiotic status of the aphid individuals had no impact on the attack rate of the parasitic wasps, the parasitoid emergence rate from parasitized aphids nor the life-history traits of the emerging parasitoids. Overall, no correlations between symbiont effects on the different stages of the host–parasitoid interaction was observed, suggesting no trade-offs or positive associations between symbiont-mediated phenotypes. Our study highlights the need to consider various sequences of the host-parasitoid interaction to better assess the outcomes of protective symbioses and understand the ecological and evolutionary dynamics of insect–symbiont associations.     

甘肃鼠兔贮草越冬及其生物学意义

对采自草甸、灌丛和弃耕地3 种类型栖息地共27 个甘肃鼠兔草堆的研究结果表明, 每个草堆干重在23.8～984.2 g 之间, 平均184.2 g , 总计含有26 种双子叶植物和一些禾本科单子叶植物。分析显示, 草堆大小(食物重量) 与栖息地植被类型无关。在贮存干草堆时, 甘肃鼠兔对不同植物成分具有强烈的选择性, 其中, 单子叶植物和双子叶植物分别占总重量的8.06 %和84.61 % , 与它们各自在栖息地中的生物量百分比51.76 %和39.57 %形成鲜明对照。甘肃鼠兔对植物种类的选择性在一定程度上受栖息地植被类型的影响, 但最喜食的几种植物却基本不变, 它们是美丽风毛菊、棘豆、麻花艽、禾草、线叶龙胆。人工去除栖息地中的干草堆后, 甘肃鼠兔种群越冬存活率从对照样地的51.84 %下降到21.33 % , 表明草堆食物对其成功越冬有一定正效应。野外观察证实, 甘肃鼠兔的鸣声不及同域分布的高原鼠兔发达, 但前者具有贮存食物越冬的习性, 而后者却不贮存越冬食物, 此结果不支持“鼠兔类动物建立草堆的行为与鸣声行为平行发育”的观点。     

Lifecycle effects of a recession on health behaviors: Boom,bust, and recovery in Iceland

This study uses individual-level longitudinal data from Iceland, a country that experienced a severe economic crisis in 2008 and substantial recovery by 2012, to investigate the extent to which the effects of a recession on health behaviors are lingering or short-lived and to explore trajectories in health behaviors from pre-crisis boom, to crisis, to recovery. Health-compromising behaviors (smoking, heavy drinking, sugared soft drinks, sweets, fast food, and tanning) declined during the crisis, and all but sweets continued to decline during the recovery. Health-promoting behaviors (consumption of fruit, fish oil, and vitamins/minerals and getting recommended sleep) followed more idiosyncratic paths. Overall, most behaviors reverted back to their pre-crisis levels or trends during the recovery, and these short-term deviations in trajectories were probably too short-lived in this recession to have major impacts on health or mortality. A notable exception is for binge drinking, which declined by 10% during the 2 crisis years, continued to fall (at a slower rate of 8%) during the 3 recovery years, and did not revert back to the upward pre-crisis trend during our observation period. These lingering effects, which directionally run counter to the pre-crisis upward trend in consumption and do not reflect price increases during the recovery period, suggest that alcohol is a potential pathway by which recessions improve health and/or reduce mortality.     

Lung mediated auditory contrast enhancement improves the Signal-to-noise ratio for communication in frogs

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西安市城区初中生健康危险行为调查

目的:健康相关危险行为是产生常见病、多发病的重要原因,其形成受社会、家庭等多种环境因素和自身因素影响。初中阶段是养成良好健康行为的关键时期,了解初中生健康危险行为现状,可为制定干预措施提供科学依据。方法:对西安市城区1608名初中生进行健康危险行为问卷调查,分析各种健康危险行为检出率的性别差别。结果:34.3%的初中生存在偏食行为,42.6%的初中生在过去30天内采取过减肥措施;62.2%的初中生最多有2天运动超过30分钟;65.3%的初中生骑自行车违规;9.6%的初中生目前吸烟。过去1个月有大量饮酒行为者占8.4%。因上网影响学习者占17.0%;参与过类似赌博的娱乐活动者占9.8%。多数健康危险行为检出率男生高于女生(P值均0.05)。结论:西安市城区初中生健康危险行为发生率较高,男女生间存在差异,应针对男女生不同健康危险行为,采取有针对性的综合干预措施进行干预,以及早纠正健康危险行为,促进青少年健康发展。     

Collective behaviours in organoids

Collective behaviour emerges from interacting units within communities, such as migrating herds, swimming fish schools, and cells within tissues. At the microscopic level, collective behaviours include collective cell migration in development and cancer invasion, rhythmic gene expression in pattern formation, cell competition in homeostasis and cancer, force generation and mechano-sensing in morphogenesis. Studying the initiation and the maintenance of collective cell behaviours is key to understand the principles of development, regeneration and disease. However, the manifold influences of contributing factors in in vivo environments challenge the dissection of causalities in animal models. As an alternative model that has emerged to overcome this difficulty, in vitro three-dimensional organoid cultures provide a reductionist approach yet retain similarities with the in vivo tissue in cellular composition and tissue organisation. Here, we focus on recent progresses in studying collective behaviours in different organoid systems and discuss their advantages and the possibility of improvement for future applications.     

PSPH induces cell autophagy and promotes cell proliferation and invasion in the hepatocellular carcinoma cell line Huh7 via the AMPK/mTOR/ULK1 signaling pathway

Phosphoserine phosphatase (PSPH), a key enzyme of the l -serine synthesis pathway, has been involved in cancer progression and survival. However, limited evidence revealed the PSPH influence on hepatocellular carcinoma (HCC). Herein, we observed that PSPH expression was upregulated in both HCC tissues and cell lines, which was determined by western blotting. TCGA database showed that the PSPH protein levels were significantly upregulated and affected patient survival rates in HCC. Then gain- and loss-of-function manipulations were performed by transfection with a pcDNA-PSPH expression vector or a specific short interfering RNA against PSPH in Huh7 cells. Huh7 cell proliferation, stemness, invasion, and apoptosis were assessed by using CCK-8 test, colony formation assay, Transwell assay, and Flow cytometry analysis, respectively, and levels of autophagy-related proteins were detected by using western blotting. The results showed that PSPH could induce Huh7 cell autophagy, promote cell proliferation and invasion, and inhibit apoptosis. The knockdown of PSPH could inhibit Huh7 cell proliferation, invasion, and autophagy. Furthermore, PSPH activated Liver kinase B1 (LKB1) and TGF beta-activated kinase 1 (TAK1), affected the adenosine 5′-monophosphate-activated protein kinase (AMPK)/mTOR/ULK1 signaling pathway, but could not activate calcium/calmodulin-dependent protein kinase kinase (CaMKK) in Huh7 cells. Inhibition of either LKB1, TAK1, or AMPK could eliminate the effect of PSPH overexpression on Huh7 cell behaviors. However, inhibition of CaMKK could not influence the effect of PSPH overexpression on Huh7 cell behaviors. In conclusion, PSPH could induce autophagy, promote proliferation and invasion, and inhibit apoptosis in HCC cells via the AMPK/mTOR/ULK1 signaling pathway.     

Behavioral responses to the 2015 MERS epidemic in Korea

Understanding behavioral responses to epidemics is important in evaluating the broad health consequences of emerging infectious diseases. Building on the economic epidemiology literature, this study investigates individual behavioral responses to the 2015 Middle East Respiratory Syndrome Coronavirus (MERS-CoV) epidemic in Korea using a panel of individuals in a nationally representative survey. Results show that exposure to the epidemic led to lasting impacts on smoking and drinking behaviors, indicating that emerging infectious disease outbreaks are motivations for behavioral changes and opportunities for public policy interventions. In particular, individuals in the hardest-hit regions or socially connected persons were more likely to change their risky behaviors, suggesting that intensity of exposure and social interactions are potential mechanisms.     

Complicated trafficking behaviors involved in paradoxical regulation of sortilin in lipid metabolism

This review aims to summarize and discuss the most recent advances in our understanding of the underlying mechanisms of the paradoxical effects of sortilin on lipid metabolism. The vacuolar protein sorting 10 protein (Vps10p) domain in the sortilin protein is responsible for substrate binding. Its cytoplasmic tail interacts with adaptor molecules, and modifications can determine whether sortilin trafficking occurs via the anterograde or retrograde pathway. The complicated trafficking behaviors likely contribute to the paradoxical roles of sortilin in lipid metabolism. The anterograde pathway of sortilin trafficking in hepatocytes, enterocytes, and peripheral cells likely causes an increase in plasma lipid levels, while the retrograde pathway leads to the opposite effect. Hepatocyte sortilin functions via the anterograde or retrograde pathway in a complicated and paradoxical manner to regulate apoB-containing lipoprotein metabolism. Clarifying the regulatory mechanisms underlying the trafficking behaviors of sortilin is necessary and may lead to artificial sortilin intervention as a potential therapeutic strategy for lipid disorder diseases. Conclusively, the paradoxical regulation of sortilin in lipid metabolism is likely due to its complicated trafficking behaviors.