一种用于DAPI染色的方法Steedman＇s wax包埋切片法

以植物的胚珠和子房为实验材料,介绍一种用Steedrnan‘s wax包埋对组织切片中的细胞核进行DAPI染色的方法。Steedrnan‘s wax作为一种低熔点多酯蜡,具有与石蜡相似的性质,切片方法同常规石蜡切片,适合于切成厚度大于5μm的连续切片。Steedrnan‘s wax包埋的切片能成功地进行DAPI染色。与用压片法和Technovit 7100或GMA包埋切片法进行的DAPI染色相比,用Steedrnan‘s wax包埋切片法进行的DAPI染色具有廉价、操作简便、可进行连续切片、图象清晰等优点,特别在植物细胞程序化死亡(PCD)的研究中及细胞核DNA含量测定方面,有着较大的应用价值和潜能。     

应用Steedman's wax切片法观察植物细胞微管骨架

微管骨架在植物发育过程中起重要作用.由于植物细胞的特殊性,与动物细胞相比植物微管骨架的研究遇到更多的困难.简略地介绍了曾被国内外学者应用的植物微管骨架的各种研究方法及其局限性.Steedman's wax是一种多脂蜡.它熔点低(35～37℃),具有与石蜡相同的切片性质,能够切成不同厚度的连续切片,适合深埋于器官内部的组织或细胞的免疫细胞化学研究.介绍了应用Steedman's wax切片法观察植物细胞微管骨架的一般程序和方法以及经过作者检验且切实可行的一些技术改进.     

应用Steedman's wax 切片法观察植物细胞微管骨架

微管骨架在植物发育过程中起重要作用。由于植物细胞的特殊性,与动物细胞相比植物微管骨 架的研究遇到更多的困难。简略地介绍了曾被国内外学者应用的植物微管骨架的各种研究方法及其局限 性。Steedman's wax是一种多脂蜡。它熔点低(35~37℃),具有与石蜡相同的切片性质,能够切成不同厚 度的连续切片,适合深埋于器官内部的组织或细胞的免疫细胞化学研究。介绍了应用Steedman's wax 切 片法观察植物细胞微管骨架的一般程序和方法以及经过作者检验且切实可行的一些技术改进。     

果蝇胚胎石蜡切片制作方法的改良

探索一种不用在卵壳上手工打孔、适用于果蝇胚胎石蜡切片制作的方法。实验前期对果蝇胚胎进行渗透化处理,后期用琼脂糖、明胶、石蜡3种包埋辅佐剂对胚胎进行聚集、包埋、切片,最后进行HE及PASM染色。渗透化处理后的胚胎用琼脂糖或石蜡聚集并包埋后所制切片HE染色均显示胚胎形态结构正常,背景干净,而琼脂糖聚集法所制切片PASM染色背景呈灰色,明胶聚集法所制切片HE染色和PASM染色背景均显杂色且胚胎出现形变。3种包埋辅佐剂中,琼脂糖和石蜡均适于果蝇胚胎结构的保存,石蜡聚集法所制切片2种染色背景均无杂色,因此最适合做包埋辅佐剂。渗透化处理和石蜡聚集法结合后的改良方法适合于大样本且高脂含量的果蝇胚胎石蜡切片的制备。     

三种不同脂肪染色方法的比较

目的探讨碳蜡(聚乙二醇)包埋技术、冰冻切片及饿酸染色在脂肪染色中的应用,综合比较几种方法的优缺点,以便在病理工作及科研工作中能找到更适合的脂肪染色方法。方法取新鲜脂肪组织及肝组织,每份标本各取3块组织,分为A、B、C三组:A组和B组标本分别进行碳蜡包埋切片和常规冰冻切片,油红O法染色;C组以饿酸浸染组织块后进行石蜡包埋切片及眦复染。结果 A组切片脂肪滴呈红色,细胞核呈蓝色;B组切片脂肪滴呈红色,细胞核呈蓝色;C组切片脂肪滴呈黑色。结论饿酸染色和碳蜡包埋技术在脂肪染色中,具有冰冻切片和石蜡切片的优点,弥补了常规冰冻切片脂肪染色的缺点和局限性,在病理检验及科研中具有一定应用价值。     

一种简单快速植物组织冰冻切片方法

比较不同冷冻方法对植物细胞超微结构的影响,结果表明:直接包埋法处理的植物细胞超微结构保存较好,而液氮冷冻处理的植物细胞内膜系统损伤严重.建立了一种直接包埋冷冻和适当回温相结合的方法,不仅可以制作出植物细胞基本结构保存完整的组织切片,而且避免了使用冰冻保护剂的弊端.其操作程序是:样品固定→冰冻与包埋→适当回温→快速切片→展片→染色.此法制作的切片可进行不同的染色和组织细胞化学测定,具有操作简便,易于推广的特点.     

碱性磷酸酶钙-钴法染色的不同包埋方法比较

目的探讨石蜡切片、冰冻切片及碳蜡(聚乙二醇)包埋切片在碱性磷酸酶染色中的应用,综合分析几种组织处理方法的优缺点,以便在病理诊断及科研工作中能找到更适合的碱性磷酸酶染色方法。方法取新鲜乳腺组织及肝组织,每份标本各取3块组织,根据包埋方法的不同,分为3组:石蜡切片碱性磷酸酶染色、冰冻切片碱性磷酸酶染色、碳蜡包埋切片碱性磷酸酶染色。结果 3组切片均可见黑色碱性磷酸酶的存在,其中肝组织内显示碱性磷酸酶呈黑色,沿胆小管分布;乳腺组织内显示碱性磷酸酶呈黑色沉淀弥漫分布于乳腺间质中。结论碳蜡包埋切片在碱性磷酸酶染色中,具有冰冻切片和石蜡切片的优点,并弥补了常规冰冻切片和石蜡切片染色的缺点和局限性,在病理诊断及科研工作中具有一定的应用价值。     

盐生肉质草本植物海马齿叶片石蜡切片简易方法

海马齿是海边盐生肉质草本植物,由于叶片的肉质化,传统石蜡切片制作路线不能制作出结构完整,效果较好的切片.本实验以传统的石蜡切片方法为基础,在固定方法选择,脱水时间控制,包埋温度,染色等方面做了适合海马齿叶片特点的改良,固定方法采用戊二醛固定液固定24 h,并洗脱;脱水每级梯度时间为1 h,包埋温度在100℃,染色方法采用固绿染色法.结果表明:采用这种改良的方法可以制作出染色清晰,组织结构完整的海马齿叶片切片.这对其它肉质化植物的石蜡切片制作有着借鉴作用.     

石蜡包埋植物材料在去除石蜡之前的番红──快绿染色法

石蜡包埋植物材料在去除石蜡之前的番红──快绿染色法染色步骤：ＦＡＡ固定液固定植物材料,乙醇一正丁醇系列脱水,植物材料呈透明体状态被包埋,切片厚度１０微米。用蛋白或明胶粘片剂粘贴蜡带,切片放在４０～４５℃烫板上烘干。不脱蜡直接进行染色,过程如下：（１）...     

蚊虫连续石蜡切片制备及染色

本研究利用塑化石蜡进行了吸血前后白纹伊蚊整个蚊虫的石蜡包埋、制片及 HE染色 ,获得了染色清晰 ,组织完整的连续石蜡切片 ,并讨论了有关蚊虫石蜡包埋及制片染色的一些注意事项。为进一步利用免疫组化、原位 PCR等技术研究虫媒病毒在蚊虫体内的分布规律提供了可能     

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.