Sex differences in relationships between habitat use and reproductive performance in Soay sheep (Ovis aries)

The role of habitat use in generating individual variation in fitness has rarely been examined empirically in natural populations of long‐lived mammals, particularly for both sexes simultaneously. This is the case despite the increase in studies attempting to understand evolutionary change in such populations. Using data from the St. Kilda Soay sheep population, we quantified the association between lifetime reproductive performance (lifetime breeding and reproductive success) and the proportion of the home range covered by a key grass species, H. lanatus, for 490 females and 304 males. Increased H. lanatus cover was associated only with increased female lifetime reproductive success, but increased lifetime breeding success for both sexes, arising through increased male longevity and increased female fecundity. This work suggests that improved understanding of the causes and consequences of fitness differences will likely require us to better account for habitat‐derived individual variation, and to do so for the sexes appropriately.     

Mosaicism in a new Eocene pufferfish highlights rapid morphological innovation near the origin of crown tetraodontiforms

Tetraodontiformes (pufferfishes and kin) is a taxonomically and structurally diverse, widely‐distributed clade of acanthomorphs, whose members often serve as models for genomics and, increasingly, macroevolutionary studies. Morphologically disparate Palaeogene fossils suggest considerable early experimentation, but these flattened specimens often preserve limited information. We present a three‐dimensionally preserved beaked tetraodontiform from the early Eocene (c. 53 Ma) London Clay Formation, UK. Approximately coeval with the oldest crown tetraodontiforms, ?Ctenoplectus williamsi gen. et sp. nov. presents an unprecedented combination of characters, pairing a fused beak‐like dentition with prominent dorsal‐fin spines that insert atop transversely‐expanded pterygiophores roofing the skull. Bayesian total‐evidence tip‐dating analysis indicates that ?Ctenoplectus represents the sister lineage of Triodontidae and highlights considerable levels of homoplasy in early tetraodontiform evolution. According to our dataset, rates of morphological character evolution were elevated at the origin of crown Tetraodontiformes, especially within gymnodonts, but declined after the principal body plans were established. Such ‘early burst’ patterns are regarded as a hallmark of adaptive radiations, but are typically associated with diversification at smaller spatiotemporal scales. However, denser sampling of Neogene and Recent taxa is needed to confirm this pattern.     

Molecular dynamics simulation of single-walled carbon nanotubes inside liquid crystals

Molecular dynamic simulations of systems of single-walled carbon nanotubes (CNTs) in liquid crystalline solvents were performed, in order to investigate the effect of the molecular structure and phase of the liquid crystal (LC) on the interactions between the CNTs. Three different LC molecules (5CB, 8CB and 5CF) were considered in our study. Our results with 5CB and 8CB suggest that increasing the chain length of the hydrophobic part of the LC molecule by three carbon atoms is insufficient to decrease the tendency for the CNTs to aggregate in the LCs. Additionally, varying the phase of the LC is also insufficient to decrease the aggregation tendency of the CNTs. However, simulations with 5CF (which has fluorine atoms in the head group of the LC molecule) suggest that this LC solvent can decrease the tendency of the CNTs to aggregate. This study is relevant to assist experimentalists with the development of high-quality dispersions of large concentrations of CNTs in the LCs.     

The influence of stomach distention on feeding in the nudibranch mollusk Melibe leonina

Although research on satiation has revealed much about the effect of sensory inputs on motivational state, we have yet to fully understand exactly how satiating signals influence the neural circuits underlying specific behaviors. One organism that is well suited for addressing this question is the nudibranch Melibe leonina, because its feeding activity is easily quantified, it has translucent skin that makes the stomach easy to observe, and it has large, identifiable neurons that are very suitable for subsequent analysis of the neural correlates of satiation. In this study our goal was to document the time course of satiation in Melibe, and determine if stomach distention contributes to satiation. When exposed to brine shrimp (Artemia), Melibe immediately commenced stereotypic oral hood movements to capture prey, and continued to do so for approximately five hours. Individuals eventually stopped, despite the continued presence of food, and the slowing and eventual termination of oral hood closures was correlated with distension of the stomach caused by the ingested Artemia. We obtained further evidence that stomach distension is one of the underlying causes of satiation by injecting artificial non-nutritive food into the stomach, and by cutting open part of the stomach wall to prevent it from filling and distending. The first treatment caused satiation to occur more rapidly, while the second treatment delayed satiation. Both results demonstrate that in Melibe stomach distention has a major impact on the motivation to feed. These findings provide the framework for subsequent studies designed to determine precisely how stomach distention influences feeding circuits.     

Mating system and early viability resistance to habitat fragmentation in a bird-pollinated eucalypt

Habitat fragmentation has been shown to disrupt ecosystem processes such as plant-pollinator mutualisms. Consequently, mating patterns in remnant tree populations are expected to shift towards increased inbreeding and reduced pollen diversity, with fitness consequences for future generations. However, mating patterns and phenotypic assessments of open-pollinated progeny have rarely been combined in a single study. Here, we collected seeds from 37 Eucalyptus incrassata trees from contrasting stand densities following recent clearance in a single South Australian population (intact woodland=12.6 trees ha⁻¹; isolated pasture=1.7 trees ha⁻¹; population area=10 km²). 649 progeny from these trees were genotyped at eight microsatellite loci. We estimated genetic diversity, spatial genetic structure, indirect contemporary pollen flow and mating patterns for adults older than the clearance events and open-pollinated progeny sired post-clearance. A proxy of early stage progeny viability was assessed in a common garden experiment. Density had no impact on mating patterns, adult and progeny genetic diversity or progeny growth, but was associated with increased mean pollen dispersal. Weak spatial genetic structure among adults suggests high historical gene flow. We observed preliminary evidence for inbreeding depression related to stress caused by fungal infection, but which was not associated with density. Higher observed heterozygosities in adults compared with progeny may relate to weak selection on progeny and lifetime-accumulated mortality of inbred adults. E. incrassata appears to be resistant to the negative mating pattern and fitness changes expected within fragmented landscapes. This pattern is likely explained by strong outcrossing and regular long-distance pollen flow.     

黄土丘陵区退耕还林地刺槐人工林碳储量及分配规律

采用样地调查与生物量实测方法,研究了甘肃黄土丘陵区不同坡向(阳坡、阴坡)和退耕年限(退耕5a、8a和11a)刺槐人工林乔木不同器官、灌草层、枯落物层和土壤层的碳含量,以及刺槐人工林乔木层、灌草层、枯落物层和土壤层碳储量及其分配特征。结果表明:刺槐不同器官碳含量均值变化范围为43.02%—50.89%%,从高到低排列顺序为树干细枝中枝粗枝叶根桩大根粗根小根中根树皮细根;灌木层碳含量为35.76%—42.74%;草本层碳含量为35.83%—43.64%;枯落物层碳含量为39.55%—41.77%;土壤层(0—100 cm)碳含量均值变化范围0.22%—0.99%,随退耕年限增加而增大,土壤深度的增加而逐渐下降。刺槐人工林生态系统碳库空间分布序列为土壤层(0—100 cm)植被层枯落物层。阳坡和阴坡退耕5a、8a、11a刺槐林生态系统碳储量分别为52.52、58.93、73.72 t/hm2和49.95、61.83、79.03 t/hm2。退耕年限和坡向是影响刺槐人工林碳储量增加的主要因素。刺槐人工林具有良好的固碳效益,是黄土丘陵区的理想树种。     

放射污染区古菌分离及多样性分析

【目的】研究放射污染区古菌多样性。【方法】放射污染区采集土样,采用甘油-精氨酸培养基(GJ)、甘油-天冬氨酸培养基(C1)、海藻糖-肌酸培养基(B7)、甘露醇-丙氨酸培养基(Z5)、干酪素-甘露醇培养基(CMKA)、壳聚糖-天冬酰胺培养基(F6)、甘露醇-酸水解酪蛋白培养基(GW1)、CM培养基、HP培养基和KC培养基10种分离培养基,采用梯度稀释法对古菌进行分离,将分离获得的菌株经形态特征,16S rRNA基因片段扩增及限制性内切酶酶切,选取酶切图谱中存在差异性的条带进行测序,最终通过序列比对,聚类分析,获得不同种类的古菌资源。【结果】从该土样中共获得了256株古菌,最终筛选出71株不同类型的古菌,这71株古菌均属于广古菌门,盐杆菌纲,盐杆菌目,盐杆菌科,分布于盐陆生菌属(Haloterrigena)、纳白菌属(Natrialba)、盐球菌属(Halococcus)、盐红菌属(Halorubrum)、盐长寿菌属(Halovivax)、纳线菌属(Natrinema)、盐碱球菌属(Natronococcus)、盐二型菌属(Halobiforma)、盐惰菌属(Halopiger)、盐池栖菌属(Halostagnicola)、富盐菌属(Haloferax)11个属,26个种,其中31株菌的16S rRNA基因序列与已有效发表菌株的序列相似性小于98%,Haloterrigena为该土样的优势菌属。对于分离效果较好的F6培养基采用了梯度营养成分的稀释,最终获得了19株古菌,这些菌株相互之间存在一定的差异性。【结论】本次分离获得了大量的古菌,表明放射污染区存在着较为丰富的古菌资源,其中蕴藏着多种新的物种类型,具有较大的研究价值。     

乌司他丁治疗急性胰腺炎的临床疗效及机制研究

目的:探讨乌司他丁对急性胰腺炎患者的临床疗效及可能机制。方法:收集我院收治的重症急性胰腺炎患者66例,随机分为实验组和对照组。所有患者均给予禁食水、充分补液、纠正电解质紊乱等常规支持对症治疗。对照组予奥曲肽,实验组予乌司他丁,共治疗7天。测定两组患者治疗前、后各血清白介素-6(IL-6)、白介素-8(IL-8)及肿瘤坏死因子-α(TNF-α)水平;治疗前、治疗第1、3天及治疗后进行血常规检测,观察白细胞计数(WBC),并进行血淀粉酶(AMS)、尿淀粉酶(UAMY)测定;分别记录两组患者临床症状及体征恢复时间,判定临床疗效。结果:1治疗后,两组患者血清IL-6、IL-8及TNF-α水平均较治疗前显著下降,且实验组较对照组下降更明显(P0.05);2治疗后,两组患者白细胞计数及血、尿淀粉酶水平均较治疗前明显下降,且实验组较对照组下降更明显(P0.05);3治疗后,实验组各项临床症状及体征消失时间均明显短于对照组(P0.05)。结论:乌司他丁可有效改善急性胰腺胰腺炎患者的各项临床症状,这可能与其显著降低其血清IL-6、IL-8、TNF-α、淀粉酶水平、白细胞计数及尿淀粉酶水平有关。     

采用代谢组学分析技术分析工业啤酒发酵过程中风味物质生成规律

啤酒风味是保证啤酒品质的关键因素之一。运用代谢组学的方法,分析工业啤酒发酵过程中酵母胞内代谢物和啤酒风味物质的对应关系,从代谢水平上研究风味物质形成过程中的关键影响因素。在啤酒发酵过程中,同时检测风味物质的含量变化和酵母胞内代谢物的变化,对得到海量的、多维的代谢数据采用主成分分析（PCA）和偏最小二乘分析（PLS）的多元统计分析方法进行处理。由PCA分析结果可知：磷酸、海藻糖、琥珀酸、谷氨酸、天冬氨酸、丙氨酸对主成分贡献比较大,说明这些代谢物在不同发酵阶段含量变化显著。由PLS分析结果可知：对啤酒风味影响最大的物质主要为氨基酸,包括丝氨酸、缬氨酸、苏氨酸、赖氨酸、丙氨酸、亮氨酸和天冬酰胺等,这为啤酒中风味物质的调控提供了一定的理论指导。