乙型肝炎病毒X蛋白的优势氨基酸序列与热点突变位点的生物信息学分析

乙型肝炎病毒X蛋白(hepatitis B virus X protein,HBx)全长154个氨基酸,与肝癌发生密切相关.为确定HBx的优势氨基酸序列和热点突变位点,在GenBank中下载所有HBx的氨基酸序列13950条,剔除插入突变、缺失突变和起始密码子非甲硫氨酸的序列,最后保留7126条.通过分析这7126条序列,计算出HBx每个位点的氨基酸分布情况,出现频率最高的氨基酸为该位点的优势氨基酸,其他氨基酸为突变氨基酸.154个位点的优势氨基酸组成HBx优势氨基酸序列.突变率>10.0%的热点突变位点有32个.其中第36、42、44、87、88和127位氨基酸有4种(突变率>1.0%)以上突变形式,具有较高的多态性.与肝癌密切相关的K130M/V131I双突变率为34.7%.通过7126条HBx序列与优势序列的同源性比较,随机选出其中50条序列(2条与优势序列同源性<75%,48条同源性为76%~99%),与23条参考序列及优势序列共同构建系统发生树.结果显示,HBx优势氨基酸序列属于基因型C,这与基因型C为全球主要流行型一致.本研究首次系统性分析了GenBank中HBx的优势序列,确定了32个HBx热点突变位点和6个多态性较高的位点,为基于HBx突变的基础和应用研究奠定了基础.     

Grey Parrots Psittacus erithacus in Kampala,Uganda – are they becoming suburbanised?

The globally Vulnerable Grey Parrot (Psittacus erithacus) has been seen in Kampala, Uganda’s capital city, in increasing numbers in recent years. This apparently new behaviour of a typically forest species is helped by the presence of many large trees, which provide roosting and nesting sites, and fruiting trees where they feed. Grey Parrots in Kampala potentially come from three sources: escapees, releases of captive birds or wild birds moving into a suburban environment. Birds mostly exhibit behaviours typical of wild birds, but as most, if not all, of the Grey Parrots in captivity are wild-caught and would revert to wild-caught behaviours when released, it is difficult to distinguish them from the wild population. However, we believe that at least some of the birds seen in Kampala are wild.     

圆蟾舌蛙鸣声特征分析

为研究体型较小的蛙类的鸣声特征,2012年7~8月,采用录音机和指向性话筒,在野外录制51只雄性圆蟾舌蛙(Phrynoglossus martensii)鸣声并对应测量了录音个体的体重、体长及头宽等体征数据。雄性圆蟾舌蛙的体重为(1.26±0.55)g,体长为(21.04±2.57)mm,头宽为(6.76±0.75)mm。该种蛙可发出广告鸣声和争斗鸣声。广告鸣声为单音节鸣叫,主频(3 782.25±167.78)Hz,3 100~4 349 Hz;基频(1 519.69±70.60)Hz,1 057~1 765 Hz。广告鸣声主频和基频均与体重、体长、头宽呈显著负相关,而音节间隔与体重和头宽呈正相关(相关性分析)。争斗鸣声主频(3 752.64±174.47)Hz,(3 304~4 081)Hz;基频(1 674.88±79.88)Hz,1 367~1 870 Hz。与广告鸣声相比,争斗鸣声的基频显著增高(t=﹣5.374,df=56,P0.001),音节时长和音节间隔显著降低(P0.05),而主频在两种鸣声类型中无显著差异(t=0.436,df=56,P=0.665)(独立样本T检验)。结果表明,作为体型较小的蛙类,体型影响了圆蟾舌蛙的鸣声结构和类型。     

Variable prey development time suppresses predator–prey cycles and enhances stability

Although theoretical models have demonstrated that predator–prey population dynamics can depend critically on age (stage) structure and the duration and variability in development times of different life stages, experimental support for this theory is non‐existent. We conducted an experiment with a host–parasitoid system to test the prediction that increased variability in the development time of the vulnerable host stage can promote interaction stability. Host–parasitoid microcosms were subjected to two treatments: Normal and High variance in the duration of the vulnerable host stage. In control and Normal‐variance microcosms, hosts and parasitoids exhibited distinct population cycles. In contrast, insect abundances were 18–24% less variable in High‐ than Normal‐variance microcosms. More significantly, periodicity in host–parasitoid population dynamics disappeared in the High‐variance microcosms. Simulation models confirmed that stability in High‐variance microcosms was sufficient to prevent extinction. We conclude that developmental variability is critical to predator–prey population dynamics and could be exploited in pest‐management programs.     

四川省不同天然种群珙桐叶片解剖结构与其耐热性的关系

以四川省15个珙桐种群为试材,采用石蜡切片法、NaClO法观察叶片16项解剖结构,应用变异系数、聚类分析、相关性分析对叶片解剖结构进行筛选,利用隶属函数法对不同种群的耐热性进行综合评价,以期了解珙桐应对热胁迫的生理变化机制,为野生珙桐资源的保护及园林应用提供参考。结果表明：珙桐叶片为异面叶,气孔主要分布于下表皮。16项解剖结构指标在不同种群间达到极显著差异水平;栅海比、栅栏组织厚度、气孔密度、下表皮角质厚度、主脉凸起度、上表皮角质层厚度、下表皮细胞厚度是影响珙桐耐热性的主要解剖结构指标,叶厚度、海绵组织厚度、主脉厚度、上表皮细胞厚度、主脉维管束厚度、气孔长度、气孔宽度、叶片结构紧密度、叶片结构疏松度与耐热性关系不大;15个珙桐种群耐热性存在一定差异,其强弱顺序为：汉源 > 筠连 > 雷波 > 沐川 > 屏山 > 荥经 > 天全 > 美姑 > 平武 > 碧峰峡 > 北川 > 洪雅 > 宝兴 > 大邑 > 邛崃;15个种群耐热性大致分为4类：汉源种群为耐热型,筠连、雷波、沐川等3个种群为中度耐热型,屏山、荥经、天全、美姑、平武、碧峰峡、北川为低耐热型,洪雅、宝兴、雷波、邛崃等4个种群为不耐热型。     

Excavating ghost footprints and tangled trees from modern genomes

Due to pervasive gene flow and admixture, simple bifurcating trees often do not provide an accurate representation of relationships among diverging lineages, but limited resolution in the available genomic data and the spatial distribution of samples has hindered detailed insights regarding the evolutionary and demographic history of many species and populations. In this issue of Molecular Ecology, Foote et al. (2019) combine a powerful sampling design with novel analytical methods adopted from human genetics to describe previously unrecognized patterns of recurrent vicariance and admixture among lineages in the globally distributed killer whale (Orcinus orca). Based on sequence data from modern samples alone, they discover clear signatures of ancient admixture with a now extinct “ghost” lineage, providing one of the first accounts of archaic introgression in a nonhominid species. Coupling a cost‐effective sequencing strategy with novel analytical approaches, their paper provides a roadmap for advancing inference of evolutionary history in other nonmodel species, promising exciting times ahead for our field.     

长叶榧黄酮类化合物含量及成分分析

对长叶榧不同营养器官和不同居群的3种营养器官黄酮类化合物含量进行测定,并利用聚酰胺薄层层析法对黄酮类化合物的成分进行分析。结果表明：（1）长叶榧各个营养器官均含有黄酮类化合物,其含量高低顺序依次是一年生叶>一年生枝>幼根>老根>树皮>老枝>茎;（2）长叶榧不同营养器官其黄酮类化合物的种类有很大的差异,以一年生叶、一年生枝最多,幼根次之,老根、老枝第三,树皮、茎最少;（3）不同长叶榧居群3种营养器官黄酮类化合物含量各不相同,但均以一年生叶最高,一年生枝次之,老枝最低;（4）不同长叶榧居群一年生叶黄酮类化合物含量差异不显著,一年生枝、老枝差异较大;（5）不同长叶榧居群3种营养器官其黄酮类化合物的种类在一年生叶中没有差异,一年生枝中差异较小,老枝中差异较大。     

Caspases in yeast apoptosis-like death: facts and artefacts

Various findings suggest that programmed cell death (PCD) is induced in yeast as a response to the impact of a deleterious environment and/or an intracellular defect. Moreover, the specifically localized PCD within multicellular colonies seems to be important for the safe degradation of cell subpopulations to simple compounds that can be used as nutrients by healthy survivors occurring in propitious colony areas, being thus important for proper development and survival of the yeast population. In spite of this, the question remains whether yeast dies by real apoptosis, i.e. death involving caspases, or by other kinds of PCD. A large group of mammalian caspases includes those that are responsible for monitoring of the stimulus and initiating the dying process, as well as those involved in the execution of death. Additionally, paracaspases and metacaspases, that share some homology with real caspases, but possibly differ in substrate specificity, have been identified in plants, fungi, Dictyostelium and metazoa. In yeast, one homologue of caspases, metacaspase Mca1p/Yca1p, has been identified so far, although there are several indications of the presence of other caspase-like activities in yeast. In this minireview, we summarize various data on the possible involvement of Mca1p and other caspase-like activities in yeast PCD.     

中国生物多样性核心监测指标遥感产品体系构建与思考

生物多样性的稳定维持关乎人类生存发展与地球健康。生物多样性核心监测指标(Essential Biodiversity Variables, EBVs)旨在结合地面调查与遥感技术, 为大尺度、长时间序列的生物多样性监测提供新的解决方案。然而, 目前学界仍然缺乏一套国家尺度标准化EBVs遥感监测产品数据集, 以进行生物多样性评估。本研究旨在对中国生物多样性核心监测指标遥感产品进行体系构建与思考, 首先综述了目前EBVs的遥感研究概况, 并根据EBVs研究文献的数量进行调研分析; 同时, 本文在已有遥感生物多样性产品优先标准的基础上, 添加了“可重复性”的新标准, 并据此构建了中国EBVs遥感产品体系与监测数据集的指标清单, 最终对中国EBVs遥感研究存在的问题进行思考与讨论。本研究可为中国的生物多样性遥感监测提供科学依据, 有望为中国生物多样性政策的制定提供支撑。