The first chromosome‐level genome for a marine mammal as a resource to study ecology and evolution

Marine mammals are important models for studying convergent evolution and aquatic adaption, and thus reference genomes of marine mammals can provide evolutionary insights. Here, we present the first chromosome‐level marine mammal genome assembly based on the data generated by the BGISEQ‐500 platform, for a stranded female sperm whale (Physeter macrocephalus). Using this reference genome, we performed chromosome evolution analysis of the sperm whale, including constructing ancestral chromosomes, identifying chromosome rearrangement events and comparing with cattle chromosomes, which provides a resource for exploring marine mammal adaptation and speciation. We detected a high proportion of long interspersed nuclear elements and expanded gene families, and contraction of major histocompatibility complex region genes which were specific to sperm whale. Using comparisons with sheep and cattle, we analysed positively selected genes to identify gene pathways that may be related to adaptation to the marine environment. Further, we identified possible convergent evolution in aquatic mammals by testing for positively selected genes across three orders of marine mammals. In addition, we used publicly available resequencing data to confirm a rapid decline in global population size in the Pliocene to Pleistocene transition. This study sheds light on the chromosome evolution and genetic mechanisms underpinning sperm whale adaptations, providing valuable resources for future comparative genomics.     

ENSO and NAO affect long‐term leaf litter dynamics and stoichiometry of Scots pine and European beech mixedwoods

Litterfall dynamics (production, seasonality and nutrient composition) are key factors influencing nutrient cycling. Leaf litter characteristics are modified by species composition, site conditions and water availability. However, significant evidence on how large‐scale, global circulation patterns affect ecophysiological processes at tree and ecosystem level remains scarce due to the difficulty in separating the combined influence of different factors on local climate and tree phenology. To fill this gap, we studied links between leaf litter dynamics with climate and other forest processes, such as tree‐ring width (TRW) and intrinsic water‐use efficiency (iWUE) in two mixtures of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) in the south‐western Pyrenees. Temporal series (18 years) of litterfall production and elemental chemical composition were decomposed following the ensemble empirical mode decomposition method and relationships with local climate, large‐scale climatic indices, TRW and Scots pine's iWUE were assessed. Temporal trends in N:P ratios indicated increasing P limitation of soil microbes, thus affecting nutrient availability, as the ecological succession from a pine‐dominated to a beech‐dominated forest took place. A significant influence of large‐scale patterns on tree‐level ecophysiology was explained through the impact of the North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation (ENSO) on water availability. Positive NAO and negative ENSO were related to dry conditions and, consequently, to early needle shedding and increased N:P ratio of both species. Autumn storm activity appears to be related to premature leaf abscission of European beech. Significant cascading effects from large‐scale patterns on local weather influenced pine TRW and iWUE. These variables also responded to leaf stoichiometry fallen 3 years prior to tree‐ring formation. Our results provide evidence of the cascading effect that variability in global climate circulation patterns can have on ecophysiological processes and stand dynamics in mixed forests.     

Excessive rainfall leads to maize yield loss of a comparable magnitude to extreme drought in the United States

Increasing drought and extreme rainfall are major threats to maize production in the United States. However, compared to drought impact, the impact of excessive rainfall on crop yield remains unresolved. Here, we present observational evidence from crop yield and insurance data that excessive rainfall can reduce maize yield up to ?34% (?17 ± 3% on average) in the United States relative to the expected yield from the long‐term trend, comparable to the up to ?37% loss by extreme drought (?32 ± 2% on average) from 1981 to 2016. Drought consistently decreases maize yield due to water deficiency and concurrent heat, with greater yield loss for rainfed maize in wetter areas. Excessive rainfall can have either negative or positive impact on crop yield, and its sign varies regionally. Excessive rainfall decreases maize yield significantly in cooler areas in conjunction with poorly drained soils, and such yield loss gets exacerbated under the condition of high preseason soil water storage. Current process‐based crop models cannot capture the yield loss from excessive rainfall and overestimate yield under wet conditions. Our results highlight the need for improved understanding and modeling of the excessive rainfall impact on crop yield.     

Evolution of the field of ecological restoration over the last three decades: a bibliometric analysis

Ecological restoration studies have been widely conducted for many years to solve eco‐environmental problems. However, no publications offer a systematic and quantitative analysis of the evolution of the field of ecological restoration. To address this knowledge gap, for the first time, we applied a bibliometric analysis approach to analyze ecological restoration studies. We analyzed 3,929 articles published between 1988 and 2017 catalogued in the Science Citation Index Expanded database and the Social Sciences Citation Index database. The results show that annual article output stably increased after 2004, and the number of annual articles of each country has also increased notably since then. The United States occupies the leading position in ecological restoration studies, with China attaining a close second position in recent years. Four institutions and seven journals are outstanding in the field of ecological restoration. Academic collaborations of authors or institutions exhibit an increasing trend, but international collaboration needs to be strengthened because eco‐environmental problems are a global challenge. Forest, grassland, and wetland ecosystems have received the most attention. Biodiversity, ecosystem services, and climate change are core issues of ecological restoration studies and are predicted to remain the research hotspots in the future. Novel ecosystems are likely to become one of the most important research areas in the near future. More importantly, it is crucial for researchers to places more emphasis on social issues of ecological restoration in the future.     

C-Phycocyanin elicited antitumor efficacy via cell-cycle arrest,apoptosis induction,and invasion inhibition in esophageal squamous cell carcinoma

Objectives: Mounting evidence has demonstrated that C-Phycocyanin (C-PC) exhibits marked antitumor activity in a wide type of tumors, such as pancreas cancer, breast carcinoma, lung cancer, and colon cancer. The current study aimed to confirm the antitumor efficacy of C-PC in esophageal squamous cell carcinoma (ESCC).

Methods: The efficacy of C-PC was evaluated against the proliferation of ESCC cell lines EC9706 and EC1 by CCK-8 kit and in a mice model of ESCC EC9706. Cell cycle and apoptosis were investigated by flow cytometry, and cell invasion was determined via transwell chamber. Protein expression was examined by Western blots.

Results: We found that C-PC exhibited anti-proliferation ability in a time-dependent manner and a dose-dependent manner in ESCC EC9706 and EC1 cells. Besides, C-PC markedly arrested cell cycle in the G0/G1 phase, induced cell apoptosis and suppressed cell invasion ability in both EC9706 and EC1 cells (p?<?.01). Notably, C-PC evoked the elevations of Bax, PARP, and cleaved-caspase-3 protein, but reduced cyclin D1, CDK4, Bcl-2, MMP-2, and MMP-9 expression levels. Further investigation from in vivo experiment revealed that C-PC displayed significant antitumor efficacy in the xenografted EC9706 model.

Conclusions: Our data presented herein suggest C-PC exerts antitumor efficacy in ESCC.     

硕士研究生参与本科生组织学与胚胎学实验课教学的体会

硕士研究生通过参与本科生组织学与胚胎学实验课教学,可加深对本专业知识的理解,建立更合理的知识结构,完善自身的思维体系,提高综合能力,从中发现自身不足之处并积极弥补。硕士研究生参与本科生教学具有独特的优势,对提升其综合素质有所助益。     

基因敲除技术及其在研究线粒体动力学与胰岛素抵抗关系中的应用进展

线粒体动力学即线粒体融合和分裂保持动态平衡的过程,该过程由融合/分裂相关蛋白精确调控完成,对于线粒体代谢、质量和功能有着重要的生理意义,而这些蛋白发生异常可引发线粒体动力学失衡,进而引起线粒体功能障碍并引发各种疾病状态。文中围绕基因敲除技术,详细阐述了编码融合/分裂相关蛋白的基因敲除鼠在胰岛素抵抗研究工作中的作用及应用进展,以期为今后研究线粒体动力学失衡致胰岛素抵抗的信号转导机制奠定基础。     

Responses of morphological and physiological traits to herbivory by snails of three invasive and native submerged plants

3种入侵和本地沉水植物形态和生理性状对螺类牧食的响应 沉水植物水盾草(Cabomba caroliniana)已成为中国太湖流域的优势入侵水生植物。与外来物种的原产地环境相比,引入地新环境中存在的专食性天敌较少。外来物种可能会逃避其原产地环境中的天敌牧食,又因为它们的适口性相对较差,从而导致在引入地外来物种通常比本地物种遭受的牧食者影响更低(天敌逃逸假说)。本研究的目的是比较水盾草与共生的本地沉水植物对本地牧食者的响应。我们进行了一个中宇宙尺度实验,研究了水盾草和两种共生的本地沉水植物黑藻(Hydrilla verticillata)和穗花狐尾藻(Myriophyllum spicatum)对两种本地广食性腹足纲螺类萝卜螺(Radix swinhoei)和环棱螺(Sinotaia quadrata)的牧食响应。记录了它们的形态性状指标(总生物量、冠根比和相对生长率)和生理性状指标(叶片总非结构性碳、木质素和纤维素)。研究结果表明,环棱螺对3种沉水植物性状指标的影响较少。随着本地广食性螺类萝卜螺数量的增加,黑藻和穗花狐尾藻大部分植物性状发生了改变,而水盾草的植物性状表现出相对稳定的趋势。水盾草对萝卜螺的牧食更具抵抗力,这与天敌逃逸假说的假设一致。这一发现说明牧食性螺类促进了水盾草的入侵,这可能会改变沉水植物群落中的物种组成。     

Protective Effect of Levilactobacillus brevis Against Yersinia enterocolitica Infection in Mouse Model via Regulating MAPK and NF-κB Pathway

Probiotics and Antimicrobial Proteins - Although the use of the probiotic bacterium Lactobacillus for the treatment and prevention of diseases caused by various pathogenic bacteria has received...