羚牛也缠绵

在我国西部秦岭山区,生活着一种强悍、雄健的动物——羚牛。羚牛为大型食草动物,是一种古老的孑遗种类。它外形似牛,但分类上属于牛科羊亚科,属寒带羚羊,体形粗壮,并生有一对似牛的角,角从头部长出后翻转向外侧伸出,呈扭曲状。     

扭角羚爱上玩直播

正自从上次在《好忙好忙的秦岭》中亮相以后,羚牛成了秦岭的明星动物。动物爱好者们慕名而来,却发现羚牛的身影很难找。好不容易碰上一头,竟然还是脾气暴躁的单身羚牛。一传十,十传百,羚牛成了暴躁的代名词。"哎呀,这是偏见!"羚牛们表示很冤枉。于是,大家做出了一个决定——上网开直播,向网友们展示自己的温馨日常。入驻直播间直播第一天,羚牛们挨个在镜头前亮相,正式自我介绍:"我们的外号叫六不像。     

秦岭羚牛体色的补充描述

Cooper(1923)描述秦岭羚牛(Budorcas taxicolor bedfordi)体色时这样写:“秦岭羚牛的体色为白色或金黄色”。     

用mtDNA序列探讨羚牛亚种分类(偶蹄目:牛科)

羚牛4个亚种在我国均有分布,且四川亚种和秦岭亚种是我国的特产动物,但对于分布于甘肃南部羚牛种群的亚种归属则有着不同的观点。本文就羚牛3个亚种的分类地位从线粒体DNA细胞色素b和D－Loop序列水平上进行探讨,分析结果基本支持形态学上的亚种划分,但甘肃南部羚牛种群在两个DNA片段上均与羚牛四川亚种存在着一定的差异,而与秦岭亚种则完全一致。结合羚牛地理分布特点,认为将分布于甘肃南部的羚牛种群划分为羚牛秦岭亚种可能更合适。     

秦岭羚牛的繁殖生物学

通过观察并综合有关文献,介绍了秦岭羚牛的性成熟、发情、繁殖期,雄牛的繁殖行为、繁殖策略及雌牛产仔等情况,为今后进一步研究秦岭羚牛的繁殖生物学及遗传生物学提供参考。     

秦岭羚牛( Budorcas taxicolor bedfordi )

羚牛(Budorcas taxicolor),别名扭角羚,是亚洲特有的偶蹄目牛科动物,主要产于我国,是我国国家一级重点保护动物,并在中国濒危动物红皮书中被列入濒危级保护动物.羚牛共有4个亚种,秦岭羚牛(B.t.bedfordi)是其中体型最大的一个亚种.秦岭羚牛只分布于我国秦岭山脉(北纬32～34°,东经106～110°),一般活动在沿秦岭主脊的海1 200～3 500 m之间,但在海拔700 m左右的区域也可能有极少数独牛光顾.目前秦岭羚牛的高密度分布区主要在陕西的太白、佛坪、周至、洋县、宁陕、柞水、镇安等地.与羚牛同域分布的有大熊猫(Ailuropoda melanoleuca)、金丝猴(Pygathrix roxellana)等珍稀濒危动物.     

太白山自然保护区羚牛分布的初步调查

羚牛（Ｂｕｄｏｒｃａｓｔａｘｉｃｏｌｏｒ）,为国家一级保护野生动物。羚牛秦岭亚种为我国特产亚种,分布于甘肃、陕西两省。在陕西省内分布于秦岭中、西段。羚牛在太白山自然保护区的分布情况,迄今仅见一些零星报道［１,２］。１９９６年６～９月,作者在太白山自然...     

羚牛到底有多少？

羚牛，国家一级保护动物，2006年国家林业局拟拍卖野生动物之一。秦岭羚牛，我国特有的羚牛亚种，仅分布于秦岭山脉的森林之中，在所有类型的羚牛中狩猎价格最高，每只为12000美元。     

秦岭羚牛的舔盐习性

本文报道了秦岭羚牛的舔盐行为和习性。羚牛的舔盐习性可能与繁殖活动有关。羚牛对盐源的占有具有一定的等级序位,高序位者在舔盐时处于优势地位。盐源的存在对羚牛的迁移活动有一定的影响,羚牛的舔盐习性可能会影响其家域的变化。     

羚牛四川亚种在陕西秦岭分布的新记录

羚牛(Budorcastaxicolor),别名扭角羚,隶属偶蹄目牛科,有4个亚种,分别为指名亚种(B.t.taxicolor)、不丹亚种(B.t.whitei)、四川亚种(B.t.tibetana)和秦岭亚种(B.t.bedfordi),四川亚种和秦岭亚种为中国所特有(吴家炎,1986;吴家炎等,1990)。羚牛四川亚种(简称四川羚牛)分布于甘肃东南部、四川盆地西缘和西北缘的中高山地带,其分布区跨越岷山山系、邛崃山系、相岭山系、凉山山系、大雪山和沙鲁里山系(吴家炎等,1990;胡锦矗、魏辅文,1993;魏辅文、胡锦矗,1993);秦岭亚种(简称秦岭羚牛)仅分布于秦岭山脉的山地森林中(吴家炎等,1983,1990;吴家炎…     

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.