云南姬鼠的蛋白多态性及其遗传分化关系

本文采用蛋白电泳技术对来源于云南省若干地区的姬鼠属（Ａｐｏｄｅｍｕｓ）的３种姬鼠──高山姬鼠（Ａ．ｃｈｅｖｒｉｅｒｉ）８只,中华姬鼠（Ａ．ｄｒａｃｏ）３只和大耳姬鼠（Ａ．ｌａｔｒｏｎｕｍ）１只,以及作为外群的同科的绒鼠属的大绒鼠（Ｈａｐａｌｏｍｙｓｄｅｌａｌｏｒｉ）３只进行了分析。共检测遗传座位２７个,发现２１个座位存在多态性。根据蛋白多态的数据对研究对象进行遗传分化关系的探讨,用系统分析软件ＰＨＹＬＩＰ计算它们之间的分化关系,得到了一棵无根系统树。结果表明,作为外群的大绒鼠明显不同于其它３种姬鼠而聚在最外面。８只高山姬鼠个体汇聚成独立的一支,中华姬鼠的３个个体也聚成一支,但大耳姬鼠却聚在中华姬鼠一支中,因此我们认为大耳姬鼠同中华姬鼠的分化时间可能比较晚近。     

三种姬鼠的染色体比较研究

本文采用染色体分带技术（Ｇ－,Ｃ－带和银染色）,对中华姬鼠（Ａｐｏｄｅｍｕｓｄｒａｃｏ）、大林姬鼠（Ａ．ｐｅｎｉｎｓｕｌａｅ）和大耳姬鼠（Ａ．ｌａｔｒｏｎｕｍ）的核型进行了观察分析。结果表明：３种姬鼠的２ｎ均为４８。中华姬鼠的染色体均为端着丝点染色体。大林姬鼠的常规核型中,除１对中着丝点染色体（Ｎｏ．２３）外,其余均为端着丝点染色体。大耳姬鼠的核型中,有１３对端着丝点染色体,２对亚端着丝点染色体,１对亚中着丝点染色体和７对中着丝点染色体。中华姬鼠Ｃ－带核型中,所有染色体着丝点Ｃ－带都呈强阳性,异染色质非常丰富,Ｙ染色体整条深染。在大林姬鼠Ｃ－带核型中,Ｎｏｓ．７,１１,１５,２１,２２着丝点Ｃ－带弱化甚至近阴性,其余染色体着丝点异染色质Ｃ－带都呈现程度不同的阳性。且Ｎｏｓ．２,４,７有强弱不同的端位异染色质带。Ｘ染色体着丝点区有大块的异染色质斑带出现,Ｙ染色体整条深染。大耳姬鼠除Ｎｏｓ．３,４,１０,１２,１３染色体着丝点Ｃ－带很弱外,其余染色体着丝点Ｃ－带均呈阳性,并有８对（Ｎｏｓ．１６－２３）染色体出现异染色质短臂。从总体上看,大林姬鼠和大耳姬鼠的着丝点异染色质明显比中华姬鼠的少。中华姬鼠的Ａｇ－ＮＯＲ     

EP-1对雄性中华姬鼠和黑线姬鼠繁殖力的影响

为了检测左炔诺孕酮-炔雌醚（EP-1）对雄性中华姬鼠和黑线姬鼠的不育效果, 将32只雄性中华姬鼠和30只雄性黑线姬鼠分为 30mg/kg 单剂量组、30mg/kg多剂量组和对照组, 15d 和 45d 后剖检, 比较睾丸、附睾、储精囊、精子密度、睾酮含量及睾丸组织形态的变化。结果发现：给药后第 15 天,两种试鼠的睾丸、附睾、储精囊的重量较对照组明显降低; 精子密度、睾酮含量显著下降; 曲细精管结构破坏明显。给药后第45天,处理组各生理指标继续下降,但与第15天相比差别不显著;单剂量组和多剂量组在两个时间点的差别并不显著。结果表明,EP-1对雄性中华姬鼠和黑线姬鼠的繁殖器官有显著抑制效果,单次给药与多次给药的不育效果差别不大。     

甲状腺功能对调节雄性马鹿体重和繁殖活动季节性变化的研究

本研究探讨了甲状腺功能对雄性马鹿体重和繁殖活动季节性变化的调节作用,试验１从１９８８年１月（夏季）开始到１９８９年６月（冬季）结束,对照组５头正常鹿体中,血浆Ｔ３水平具有明显的季节性变化（Ｐ＜０．０１）,在秋季和冬季较低,春季至秋季早期较高,而３头甲状腺摘除（ＴＨＸ）鹿血浆Ｔ３水平在１９８８年６月后（冬季）降低到不可测水平。在１９８８年９月以前,二组鹿的体重,睾丸直径和血浆睾酮水平的季节性变化趋势     

荒漠沙蜥繁殖生态研究

荒漠沙蜥（Ｐｈｒｙｎｏｃｅｐｈａｌｕｓｐｒｚｅｗａｌｓｋｉｉ）１年繁殖１次,有明显的季节性周期。４月初出蛰时雄性精巢已相当发育,５月其重量和体积最大,６月变小,进入精子发生的晚期,７月降到最小,８月开始回升,１０月中旬入蛰时已接近春季出蛰时水平。１年内仅７月精巢中无精子。雌性出蛰后卵细胞开始发育,４月下旬进入成熟期,６月达高峰,７月下降,８月进入休止期。每雌年产卵１～３枚或１～４枚,平均１．８３（ｎ＝４８,１９８７）和２．１７（ｎ＝４８,１９９３）。特定体长组的生殖率是影响种群年平均生殖率的主要因素。生殖周期与光周期相符,光周期是影响荒漠沙蜥生殖周期的主要气候因子。     

高山姬鼠种群年龄结构和繁殖的调查

高山姬鼠种群年龄结构和繁殖的调查黎道洪,罗蓉贵州师范大学生物科学技术系贵阳５５０００１高山姬鼠（Ａｐｔｈｅｍ。ｃｈｈａｅｒｉ）在贵州主要分布于黔西北地区的威宁、赫章、毕节、大方等地,是农田中的主要优势种。有关鼠类种群年龄结构的划分以牙齿的磨损程度为依...     

洞庭湖不同退田还湖类型区东方田鼠和黑线姬鼠的繁殖特性

针对洞庭湖区实施的“退田还湖” 重大生态环境恢复工程,以原有“围湖”造的垸田和垸外湖滩为对照,对退田还湖区(含双退与单退两种形式)的啮齿动物群落于2003 ～ 2006 年进行定位观察。采用夹捕法进行采样,于每年的1 月、4 月、7 月、10 月进行。比较洞庭湖不同退田还湖类型区东方田鼠和黑线姬鼠种群的繁殖
指标参数。总体来看,调查期间东方田鼠和黑线姬鼠的繁殖指数要比上世纪80 ～90 年代报道的要高,这与前几年其种群处于年数量低谷有关,是东方田鼠和黑线姬鼠种群负反馈机制的体现。不同类型生境间的比较结果显示,单退垸与原有生境没有明显变化,而双退垸内黑线姬鼠和东方田鼠均有较显著的变化,主要表现在双退垸内夏季东方田鼠保持高的繁殖能力和黑线姬鼠的繁殖力锐减。由于双退垸的高程优势,鼠群在夏季汛期不会迁出垸内,仅迁移集中至较高区域,这种水位变化引导的害鼠种群迁移应该是造成繁殖变化的主要原因。由于黑线姬鼠不适应这种迁移以及集中后与东方田鼠的激烈竞争,迁移到高地后的黑线姬鼠几乎停止繁殖,繁殖指数仅为0.03 (I♀ = 0.05),明显低于当期其它生境。值得注意的是夏季滞留在双退垸内的东方田鼠,繁殖强度却不减,繁殖指数达1.54 (I♀ = 3.36),与春季湖滩种群的相当。说明没有经过长距离迁移的东方田鼠种群,在夏季仍会保持较高的繁殖强度,与夏季被迫远距离迁入农田的东方田鼠种群繁殖力急剧下降形成鲜明对比。由此可知,在初夏如果有适宜的栖息地(如双退垸的高台、原有堤岸等),东方田鼠仍能保持较强繁殖力。本文揭示了双退垸内水位变化引发种群迁移后东方田鼠和黑线姬鼠繁殖能力的这种迥异表现,具体深层次原因有待进一步探讨。     

黑线姬鼠(Apodemus agrarius)的种群繁殖参数及其地理分异特征

黑线姬鼠（Apodemus agrarius）是我国广大地区的主要害鼠之一,是余庆县农田害鼠优势种,占总鼠数的94.81%。探讨其种群繁殖参数的变动规律及其地理分异特征,对其种群数量预测预报具有重要意义。通过对1987-2005年贵州省余庆县黑线姬鼠种群繁殖参数分析结果表明：研究期间共解剖标本5497只,其中,雌鼠2698只,雄鼠2799只,黑线姬鼠在当地1-11月份均可繁殖,主要繁殖期在3-10月份,每年4-5月份和8-9月份出现2次妊娠高峰。种群总性比（♀/♂）为0.96,多年平均怀孕率为36.91%±6.79%,平均胎仔数为5.33±1.07只,平均繁殖指数为0.81±0.17,平均睾丸下降率为59.13%±7.89%。不同年龄组种群繁殖力存在显著差异,随着种群年龄的增长繁殖力不断增加,成年Ⅰ组、成年Ⅱ组、老年组是种群繁殖的主体。种群繁殖参数不同年度之间比较稳定,不同月份、不同季节之间变化差异较大,具有明显的季节变化特征。年均种群密度与年均繁殖指数呈极显著正相关,与胎仔数显著正相关,与年均怀孕率、睾丸下降率、性比相关性不显著,繁殖指数是影响黑线姬鼠种群密度的重要因子。比较全国各地黑线姬鼠种群繁殖参数的地理分异特征认为,黑线姬鼠种群繁殖参数具有明显的地理分异现象,胎仔数、生殖强度由南向北逐渐增加,具有随纬度的升高趋向增加的特征;在高纬度地区繁殖时间较短;性比与纬度、经度的变化关系密切;各繁殖参数与海拔的变化相关性不明显,可排除海拔因素的影响。     

山西省代县小PiTi繁殖生物学的研究

１９８５－１９９４年的３－１１月,在山西省代县对小ＰｉＴｉ的繁殖生物学进行了研究。该鸟在山西省为夏候鸟,每年最虫３月６日迁来,最晚１１月２４日迁离,居留期为２５５天左右。种群密度在繁殖前的４月为１．３７,繁殖后的９月为１．９５（只／ｈａ）。产卵始期为５月２７日,日产１枚,窝卵数５－８枚,产出第二枚卵时开始孵卵。观察到最早孵卵期为５月２８日,孵卵期为２０－２２ｄ。雏鸟出壳先后顺序与产卵先后顺序相一致     

山地麻晰繁殖生态的研究

１９９７年３月至１９９８年８月,在徐州市近郊的牛头山对山地麻晰的繁殖生态进行了研究。３～７月为繁殖期,其中４～５月为交配产卵盛期。雌雄性比为１１．６。从交配到产卵为２６天,卵白色、革质、椭圆形。长径平均为１．３７（１．２３～１．５３）ｃｍ,短径平均为０．８６（０．７～１．０６）ｃｍ,卵重平均为０．６（０．４～０．８５）ｇ,每窝平均产卵４．１（３～５）枚。孵化期为５０天。初孵出的小麻晰尾端为蓝绿色,     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.     

Composition and diversity of bird communities in Swedish farmland–forest mosaic landscapes

CapsuleThe amount of forest (at local and landscape scales) and occurrence of residual habitats at the local scale are shown to be the major factors influencing bird community composition in farmland–forest landscapes in central Sweden.

Aims To investigate the importance of local habitat and landscape structure for breeding birds in farmland–forest landscapes in central Sweden.

Methods Breeding birds were censused at 292 points. A detailed habitat mapping was made within 300 m of the points. Within a 300–600 m radius only two major habitats (forests and arable fields) were identified.

Results Cluster analyses of bird communities identified three site types that also differed in habitat composition: (i) partially forested sites in forested landscapes; (ii) heterogeneous sites with residual habitats in mosaic landscapes; and (iii) field-dominated farmland sites in open landscapes. A total of 19 of 25 farmland bird species (restricted to farmland or using both farmland and forest) had the highest abundance in farmland sites with mosaics of forest and farmland, while only six farmland species had the highest abundance in field-dominated sites. The bird community changed from being dominated by farmland species to being dominated by forest species (common in forest landscapes without farmland) at small proportions (10–20%) of forest at the local scale. A major difference in habitat composition between heterogeneous and field-dominated sites was the occurrence of different residual habitats (e.g. shrubby areas and seminatural grasslands). These habitats seemed to influence bird community composition more than land-use, despite covering <10% of the area. Seminatural grasslands were important for bird community composition and species-richness, but grazing seemed to be less important. Among different land-use types, cereal crops were the least preferred fields. Set-asides with tall vegetation and short rotation coppices were positively associated with species-richness of farmland birds.

Conclusion In general, the composition of the landscape was important for bird community composition, although amount and distribution of forests, occurrence of residual habitats and land-use of fields at the local scale had the strongest influence on bird community composition. The possible implications of these patterns for managing farmland–forest landscapes are discussed.     

Chemical constituents from the fruits of Rhus typhina L. and their chemotaxonomic significance

This work describes the isolation and characterization of twenty-nine compounds from the fruits of Rhus typhina L., including eleven flavonoids (1–11), eleven phenols (12–22), two pentacyclic triterpenes (23–24), two organic acids (25–26), one lumichrome (27), one courmarin (28) and one pyrimidine (29) on the basis of their spectroscopic data. Compounds apigenin (1), daidzein (4), orobol (5), 3′, 5, 5′, 7-tetrahydroxyflavanone (6), naringenin (7), butein (8), (-)-catechin (9), quercetin-3-O-α-L-(3″-O-galloyl)-rhamnoside (11), 2-hydroxybenzoic acid (13), 4-hydroxybenzaldehyde (14), vanillin (15), methyl 3,4-dihydroxybenzoate (16), 3,5-dihydroxybenzamide (18), tyrosol (19), caffeic acid (20), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (21), phlorizin (22), friedelin (23), oleanolic acid (24), 4,4-dimethyl-heptanedioic acid (25), anthranilic acid (26), lumichrome (27), scoparone (28) and uracil (29) have not been recorded before in this plant. This is the first report on the occurrence of compounds 4–7, 9, 11, 13–14, 16, 18–21, 25–29 from the genus Rhus. Moreover, the chemotaxonomic significance of these isolated compounds was also summarized.