精卵相互作用：诱发仓鼠精子顶体反应的部位

65只成年仓鼠经超排卵后,于排卵前人工授精。授精后6一7小时,收集输卵管壶腹部液(AF)、活动精子和卵子包括卵丘细胞(CM)基质和透明带(ZP),以相差显微镜检查精子顶体帽状态。在AF中有65.3％精子顶体帽发生改变;顶体反应(AR)率随着精子穿过CM而增加(73.7％);当精子到达ZP后,97.1％精子完成AR。25只仓鼠体外授精表明,获能精子在CM内游动或穿过CM时,顶体帽发生改变,可达到71.4％,但AR百分率甚低。当精子到达ZP后约30分钟完成AR。虽然单独的CM不能诱发体外仓鼠精子发生AR,但它可引起精子AR的早期阶段发生改变,并协同ZP促进获能精子完成AR。同样地,可溶性CM和ZP及其复合物可明显地激发体外仓鼠精子AR。但豚鼠ZP则无此作用。这些结果提示:AF是AR早期阶段的发生部位,而CM和ZP是体内仓鼠精子AR的主要部位;CM和ZP复合物是体外精子AR的诱导者。     

肝素处理山羊精子体外获能的研究

系统研究了作用浓度、时间和温度以及输卵管上皮细胞和卵丘细胞对肝素处理山羊精子体外获能后的精子活力、质膜完整性、顶体完整率、获能比例及受精和卵裂的影响,为改善山羊精子体外获能效果和研究获能机理提供了必要的数据。主要实验结果如下：1、在获能液中添加5、10、25、50和100μg/mL肝素处理45min时,添加50和100μg/mL肝素精子获能比率最高（分别为55%和56%）,但添加100μg/mL肝素处理后顶体完整率明显（P<0.05）低于对照组。说明山羊精子获能的最佳肝素浓度为50μg/mL。2、肝素作用时间（0, 10, 20, 30, 45, 60 和120 min）的延长,获能精子比例逐渐提高。其中,肝素处理45～120 min各组的获能精子比例差异不显著（P>0.05）,处理120 min组的精子活力和质膜完整率显著低于其它各组。说明50μg/mL肝素处理精子获能的最佳时间是45～60 min。3、在42℃和38.5℃下处理时,获能精子比例显著高于15℃和37℃,但42℃处理后精子活力和顶体完整率显著低于其它温度。因此,385℃为山羊精子获能的最佳温度。4、与输卵管上皮细胞共培养获能精子比例显著高于对照组和卵丘细胞组,但精子活力、质膜完整率和顶体完整率差异不显著。输卵管上皮组的受精率（91.3％）和卵裂率（72.2％）显著高于对照组（81.2％,65.0％）。说明与输卵管上皮细胞共培养能显著提高肝素处理山羊精子体外获能的效果。     

猪卵母细胞体外成熟与冷冻附睾精子的体外受精

由屠宰母猪卵巢分离得到505枚卵母细胞,经成熟培养,其中468枚卵丘细胞扩张,成熟率为92.7％。采用冷冻的附睾精子授精,受精率为41.9％(57/136),其中单精受精率36.8％(50/136),多精受精率5.1％(7/136)。授精卵体外培养24和48小时后的卵裂率分别为5.3％(15/258)和12.9％(30/232)。把35枚早卵裂期胚胎和250枚未见卵裂的1-细胞期受精卵移入4头受体母猪的输卵管内,其中2头妊娠,分别于1990年4月10日和29日正常分娩,共生产仔猪21头。     

绵羊体外受精卵的体外发育及冷冻保存研究

将体外成熟、体外受精的绵羊卵子,在体外培养至桑椹胚—襄胚期并进行冷冻保存,观察了培养卵的体外发育和冷冻保存效果。从采自屠宰场的绵羊卵巢中抽取卵母细胞,用含有10％FCS(或NSS)、HCG、E_2和Hepes的M199培养24—26小时,再以经Ionophore A23187诱导获能的新鲜精子进行授精。授精后6—8小时移入发育用培养基内进行培养,发育用培养基为含有10％FCS(或NSS)、丙酮酸钠、Hepes的M 199。授精72小时后,FCS组和NSS组的卵裂率分别为36.9％和45.2％,后者显著高于前者。继续培养7—10天后,桑椹胚～囊胚的发育率分别为11.6％和23.4％,两者间差异极显著。将桑椹胚和囊胚冷冻保存于PBS+20％FCS+10％乙二醇冷冻液内,解冻后的胚胎形态正常率分别为82.0％和71.9％。     

家养双峰驼卵巢卵母细胞的体外受精与早期发生的初步研究

本研究将采自屠宰母驼的卵卵母细胞在含有促性腺激素和胎牛血清的Ｍ１９９培养液中培养成熟后,将公驼附睾精子于含有咖啡因和牛血清蛋白的ＢＯ培养液中进行获能培养２小时,然后将成熟卵母细胞移入经过培养的精子悬液中,６－７小时以后将卵子移入含有胎牛血清及及丙酮酸钠的Ｍ１９９中继续培养。结果表明,经过成熟培养后有４６．７％（１４／３０）的卵母细胞发育为成熟卵子,并获得了４３．２％（１６／３７）的体外受精率,实验     

冻存对自发性高血压大鼠精子顶体功能的影响

应用金霉素(CTC)荧光检测、精子穿卵试验和项体酶β-D-半乳糖苷酶活力测定等方法检测冻存对大鼠精子顶体的影响。CTC荧光反应显示,与未冻存精子比较,冻存后精子顶体反应的类型发生改变,AR型(发生了顶体反应)精子比例明显下降,冻存前为68.6％,冻存后为13.4.％,但是获能精子的比例未发生明显变化(92.6％对90.8％)。与未冻存的精子相比,冻存组精子的穿卵试验的受精指数下降(23.4±7.02对10.2±3.95),而且冻存后精子顶体酶——β-D-半乳糖苷酶活力明显下降(9.39±1.98对4.50±1.40)。结果表明冻存后精子的顶体功能受到较明显的破坏。实验结果为今后针对性地改进大鼠精子的冻存方法,改善大鼠精子的冻存保护剂提供实验和机制上的依据。     

体外生产胚胎技术

体外生产胚胎技术是胚胎工程技术的基础,其过程涉及到卵母细胞的体外成熟、精子获能和体外受精、胚胎的体外培养这三个方面。主要综述了卵母细胞体外成熟的影响因素、精子分离和获能的方法、早期胚胎体外培养的发育“阻滞”现象和体外培养体系,同时展望了该技术的发展前景 。     

大熊猫体外受精的初报

我们在大熊猫精子体外获能与异种穿卵成功的基础上,又进行了大熊猫体外受精的首次尝试。 大熊猫卵母细胞取自刚死的育龄雌性大熊猫的卵巢,经体外培养16小时后,加入在体外已获能的大熊猫精子,进行体外受精。发现精子头能穿入卵透明带并进卵膜,继续培养19小时后因污染不幸夭亡。这是大熊猫同种体外受精的第一次报道。这一新进展表明,对研究试管大熊猫又跨近了一步。人们将有可能利用这种生物高技术去主动地拯救大熊猫,为珍稀动物物种的繁殖和保存开劈了一条新途     

金黄仓鼠卵子冷冻及在人精子受精能力检测中的应用

通过对比试验,筛选出含３．０％牛血清白蛋白的ＢＷＷ培养基和２·０ｍｏｌ／Ｌ最终浓度的二甲基 亚砜（ＤＭＳＯ）冷冻保护剂配制成冷冻液,将金黄仓鼠卵以０．３－１·０℃／ｍｉｎ的冷冻速率分别降温至 －４０℃和－８０℃,再浸入液氮中冷冻保存（３～３１天）。结果表明：冷冻降温速率以０·３℃－０·５℃／ｍｉｎ 为宜,降温到一８０℃浸入液氮的冻卵存活率（６３％）比－４０℃（４６％）的高。将解冻后存活卵去除 透明带,与人获能精子进行体外穿透试验,穿卵率达３４． ４％,与新鲜卵对照组（５０％）相比,无统 计学差异（Ｐ＞０·０５）;扫描电镜观察结果与压片光镜观察相吻合。     

小鼠卵母细胞体外培养成熟及“试管小鼠”的研究

本文研究建立了一个有效的小鼠体外受精系:t。将小鼠附覃尾精子在简单合成的培荞液中休外获 能后,与体内成熟的卵母细胞共同孵育受精,然后体外培养。结果发育至2一细胞期胚胎的百分率为75一 85 %。将这些2一细胞期胚胎移植到受体小鼠输卵管,得到11只“试管小鼠”。用小鼠卵巢中未成熟卵母 细胞,经体外培养成熟后,沐外受精培养,达2一细咆期胚胎的百分率为20-40%,经移植后得到6只“试 管小鼠,,。     

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.