Welcome aboard: are birds migrating across the Mediterranean Sea using ships as stopovers during adverse weather conditions?

Birds use stopovers during migration to interrupt endurance flight in order to minimize immediate and/or future fitness costs. Stopovers on ships is considered an exceptional and anecdotal event in the ornithological literature. This does not match the experience we had in the summer of 2021, during an oceanographic campaign in the Central Mediterranean, when we regularly observed on average 2.8 birds, of at least 13 species, stopping on board during the 25 days of the campaign. The median stopping time was 42 min, ranging from a few minutes to overnight stays on board. The probability of finding a bird stopping aboard increased with wind force and cloud cover. Birds also stopped more often in a headwind and did not stop when the wind came from different directions other than the headwind. The Central Mediterranean is one of the busiest sea routes in the world, combining the mean daily number of birds on board with the thousands of ships that pass through it during the 3 months of summer migration; we estimate that nearly 4 million birds could use ships as stopover sites. This behaviour may represent a modern-day strategy that uses ships as stopovers in the event of adverse weather conditions or could act as an ecological trap, increasing the mortality of migrants. This phenomenon deserves more research attention and further studies recording body condition and tagging of individuals on board would be informative.     

PDGF-AA activates AKT and ERK signaling for testicular interstitial Leydig cell growth via primary cilia

Testes control the development of male reproductive system. The testicular interstitial Leydig cells (Leydig cells) synthesize testosterone for promoting spermatogenesis and secondary sexual characteristics. Type A platelet-derived growth factor (PDGF-AA) is one of the most important growth factors in regulating Leydig cell growth and function. Knockout of PDGF-AA or its congenital receptor PDGFR-α leads to poor testicular development caused by reducing Leydig cell numbers, supporting PDGF-AA/PDGFR-α signaling regulates Leydig cell development. Primary cilium is a cellular antenna that functions as an integrative platform to transduce extracellular signaling for proper development and differentiation. Several receptors including PDGFR-α are observed on primary cilia for initiating signaling cascades in distinct cell types. Here we showed that PDGF-AA/PDGFR-α signaling promoted Leydig cells growth, migration, and invasion via primary cilia. Upon PDGF-AA treatment, AKT and ERK signaling were activated to regulate these cellular events. Interestingly, active AKT and ERK were detected around the base of primary cilia. Depletion of ciliary genes (IFT88 and CEP164) alleviated PDGF-AA-activated AKT and ERK, thus reducing Leydig cell growth, migration, and invasion. Thus, our study not only reveals the function of PDGF-AA/PDGFR-α signaling in maintaining testicular physiology but also uncovers the role of primary cilium and downstream signaling in regulating Leydig cell development.     

卡特拉鱼形态,食性和生长的研究

观测卡特拉鱼的形态特征和1—3龄鱼主要可量性状及其比例的变动。1—3龄鱼除主食商品饲料外,同时也食较大比例的浮游生物。着重对浮游生物的种类和比例进行了分析。肠长与体长呈直线相关。Y=6.38X-89.95。1—4龄鱼体长和体重相对生长率和生长指标都随年龄增加而逐渐下降。体长与体重呈曲线相关。W=0.00002261L~(3.0569)。采用 Von.Bertalanffy 生长方程分析其生长特性。方程参数 L_∞=821.2mm,W_∞=19616.6g,t_0=0.6年,K=0.3。体长生长不具拐点,生长速度随年龄增加而递减;体重生长具拐点,其值4.3年。此时体重生长速度达最大值。4、3龄前是生长旺盛期,此后进入生长缓慢期。     

抑制CD36与Nogo-B表达抑制三阴性乳腺癌细胞增殖与迁移

分化聚类36（cluster of differentiation 36,CD36）是一种位于细胞表面的膜蛋白受体,可以结合并转运脂肪酸。内质网膜蛋白4B （Nogo-B）在肝脏中调控脂肪酸代谢而影响肝癌的发展。目前并不清楚CD36和Nogo-B的相互作用是否能够影响乳腺癌细胞的增殖和迁移。本研究在三阴性乳腺癌（triple-negative breast cancer,TNBC）细胞中同时干预CD36与Nogo-B的表达来探索它们对细胞增殖与迁移的影响。结果表明在三阴性乳腺癌细胞中,单独抑制CD36或Nogo-B的表达都能够抑制细胞的增殖与迁移;同时抑制CD36与Nogo-B的表达时,这种抑制效果更加明显,且Vimentin、B细胞淋巴瘤-2（B-cell lympoma-2,BCL2）和增殖细胞核抗原（proliferating cell nuclear antigen,PCNA）的表达受到抑制。在小鼠移植瘤模型中,E0771细胞转染CD36或Nogo-B的siRNA后成瘤能力降低;同时敲减CD36和Nogo-B时,肿瘤生长速度显著减慢。机制研究发现,抑制CD36和Nogo-B表达能够抑制脂肪酸结合蛋白4（fatty acid binding protein 4,FABP4）和脂肪酸转运蛋白4（fatty acid transport protein 4,FATP4） mRNA的含量,同时CD36和Nogo-B过表达刺激的细胞增殖被FABP4的siRNA降低,预示着抑制乳腺癌细胞中CD36与Nogo-B的表达可能通过抑制脂肪酸的吸收和转运而抑制细胞的生长和迁移。此外,抑制CD36与Nogo-B的表达可激活P53-P21-Rb信号通路,参与抑制CD36与Nogo-B表达而抑制的细胞增殖与迁移。本研究证明同时抑制CD36和Nogo-B的表达能够协同抑制三阴性乳腺癌细胞的增殖和迁移,为临床抗三阴性乳腺癌药物的开发提供了新的靶点。     

circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移

目的 鼻咽癌是一种来源于鼻咽上皮的恶性肿瘤,其临床特征之一是易发生淋巴转移,但是目前鼻咽癌转移的分子机制尚未阐明。circPVT1是由PVT1基因2号外显子反向拼接形成的环状RNA (circRNA),在多种肿瘤中表达上调,本文探讨了circPVT1在鼻咽癌侵袭迁移中的作用和分子机制。方法 通过RT-qPCR检测circPVT1及其下游miRNA和FSCN1在鼻咽癌细胞的表达情况,Transwell和划痕愈合实验检测circPVT1对鼻咽癌细胞侵袭迁移的影响,RNA pull-down实验检测circPVT1结合的miRNA,双荧光素酶报告实验检测miR-24-3p和let-7a-5p靶向抑制FSCN1 mRNA表达。结果 在鼻咽癌细胞中过表达circPVT1可以促进鼻咽癌细胞侵袭迁移,而敲低circPVT1则可以抑制鼻咽癌细胞的侵袭迁移。进一步研究发现,circPVT1可以通过竞争性吸附miR-24-3p和let-7a-5p,上调FSCN1的表达,从而促进鼻咽癌细胞的侵袭迁移。结论 circPVT1通过miR-24-3p/let-7a-5p/FSCN1轴促进鼻咽癌细胞侵袭迁移,证实c...     

晋北典型针叶人工林叶功能性状特征及其与土壤因子的关系

为了解释植物叶片的资源分配特征及其与土壤因子间的适应策略,该研究以黄土高原东北缘山西省大同市新荣区油松、樟子松人工纯林及其柠条混交林为对象,采用样方法采集样木树冠中部生长良好的轮生枝中东西南北4个方向的枝条,并在每个枝条上选择里、中、外3处有代表性的当年生叶和多年生叶;采用 “S”形采样法在每个样方内选取9个取样点,用土钻采集各样点0～20 cm土壤样品;测定分析不同造林模式下油松、樟子松异龄叶功能性状特征、土壤理化性质以及二者的关系,为人工林培育及经营提供理论支撑。结果表明：(1)不同造林模式下油松及樟子松叶功能性状的差异集中在化学计量之间;随着叶龄增长,油松、樟子松均表现出干物质含量上升,氮磷含量下降的特征。(2)土壤全磷、全氮含量分别是油松当年及多年生叶的主要解释因子,土壤全磷与当年生叶碳氮比、有机碳、碳磷比均呈显著正相关关系,与全氮、叶面积及叶干物质含量呈显著负相关关系,土壤全氮与多年生叶全磷含量呈正相关关系,与叶有机碳、碳磷比、碳氮比则呈显著负相关关系。(3)樟子松当年生叶功能性状的关键土壤因子是土壤容重、全磷含量,其与叶碳氮磷的比值、干物质含量、碳含量呈正相关关系,而与氮磷含量呈负相关关系;多年生叶功能性状的关键土壤因子是土壤容重、含水量、pH,其与叶氮磷含量呈正相关关系,与碳含量、干物质含量、比叶面积等呈负相关关系。(4)油松及樟子松纯林的叶功能性状更易向关键土壤因子含量更高的方向偏移,说明与柠条混交可有效分异叶片生长对主要土壤因子的集中需求,但混交造林模式下林木长势有所衰弱;结合研究区资源匮乏现状,林木种植密度较大,竞争加剧了生存压力导致林木生长受限。     

Low genetic diversity and population connectivity fuel vulnerability to climate change for the Tertiary relict pine Pinus bungeana

Endemic species are important components of regional biodiversity and hold the key to understanding local adaptation and evolutionary processes that shape species distributions. This study investigated the biogeographic history of a relict conifer Pinus bungeana Zucc. ex Endl. confined to central China. We examined genetic diversity in P. bungeana using genotyping-by-sequencing and chloroplast and mitochondrial DNA markers. We performed spatial and temporal inference of recent genetic and demographic changes, and dissected the impacts of geography and environmental gradients on population differentiation. We then projected P. bungeana's risk of decline under future climates. We found extremely low nucleotide diversity (average π 0.0014), and strong population structure (global F_ST 0.234) even at regional scales, reflecting long-term isolation in small populations. The species experienced severe bottlenecks in the early Pliocene and continued to decline in the Pleistocene in the western distribution, whereas the east expanded recently. Local adaptation played a small (8%) but significant role in population diversity. Low genetic diversity in fragmented populations makes the species highly vulnerable to climate change, particularly in marginal and relict populations. We suggest that conservation efforts should focus on enhancing gene pool and population growth through assisted migration within each genetic cluster to reduce the risk of further genetic drift and extinction.     

HETEROCHRONIC DEVELOPMENTAL PLASTICITY IN LARVAL SEA URCHINS AND ITS IMPLICATIONS FOR EVOLUTION OF NONFEEDING LARVAE

Preexisting developmental plasticity in feeding larvae may contribute to the evolutionary transition from development with a feeding larva to nonfeeding larval development. Differences in timing of development of larval and juvenile structures (heterochronic shifts) and differences in the size of the larval body (shifts in allocation) were produced in sea urchin larvae exposed to different amounts of food in the laboratory and in the field. The changes in larval form in response to food appear to be adaptive, with increased allocation of growth to the larval apparatus for catching food when food is scarce and earlier allocation to juvenile structures when food is abundant. This phenotypic plasticity among full siblings is similar in direction to the heterochronic evolutionary changes in species that have greater nutrient reserves within the ova and do not depend on particulate planktonic food. This similarity suggests that developmental plasticity that is adaptive for feeding larvae also contributes to correlated and adaptive evolutionary changes in the transition to nonfeeding larval development. If endogenous food supplies have the same effect on morphogenesis as exogenous food supplies, then changes in genes that act during oogenesis to affect nutrient stores may be sufficient to produce correlated adaptive changes in larval development.     

Evaluation of the risk of overwintering Helicoverpa spp. pupae under irrigated summer crops in south-eastern Australia and the potential for area-wide management

Surveys were undertaken to determine the distribution of overwintering pupae of two species of Helicoverpa in south‐eastern Australia. The results indicate that significant populations of H. armigera have the potential to overwinter as pupae in the region under residues of their summer crop hosts. H. punctigera, conversely, was found not to overwinter in the region to any significant degree. The results also suggest that a high proportion of the overwintering H. armigera population are located in relatively few high risk fields. The overwintering population represents an ideal opportunity for control on an area‐wide basis using post harvest cultivation or “pupae busting”. The risk of overwintering H. armigera pupae occurring was largely associated with crop type, the mechanism being related to the date that the crop flowers, the level of pupal parasitism and the use of larval control measures. The results are discussed in terms of recommendations for farmers and it is suggested that a concerted effort to cultivate high risk fields has the potential to significantly reduce the population on an area‐wide basis.     

Temporal Variation in the Relative Abundance of Fruit Bats (Megachiroptera: Pteropodidae) in Relation to the Availability of Food in a Lowland Malaysian Rain Forest

The aims of this study were to investigate the diet and relative abundance of fruit bats in a lowland Malaysian rain forest and to test the hypothesis that the local assemblage structure of fruit bats varies significantly over time in relation to the availability of food. In total, 352 fruit bats of eight species were captured during 72,306 m² mist‐net hours of sampling between February 1996 and September 1999. Three species of fruit bats (Balionycteris maculita, Chironax melanocephalus, and Cynopterus brachyotis) that fed on a wide range of “steady state” and “big bang” food resources were captured continuously throughout the study period, with no significant variation in capture rates over time. In contrast, five species that fed exclusively or almost exclusively on “big bang” food resources were sampled intermittently, with significant temporal variation in the capture rates of two species (Cynopterus horsfieldi and Megaerops ecaudatus). Significant variation in the capture rates of the remaining three species (Dyacopterus spadiceus, Eonycteris spelaea, and Rousettus amplexicaudatus) could not be detected due to small sample sizes. Since ephemeral “big bang” food resources were only sporadically available within the study area and were associated with large canopy trees and strangler figs, these results suggest that food abundance, or the availability of specific food items, may be important factors limiting local fruit bat species diversity in old‐growth Paleotropical rain forest. Thus, only three fruit bat species were locally resident within the forest throughout the study period. Therefore, further studies on the ranging behavior and habitat requirements of Malaysian fruit bats are required to assess the adequacy of existing reserves and protected areas.