红原县引种早熟与晚熟猫尾草的核型分析

对红原县引种早熟与晚熟猫尾草(Phleum pratense L.)细胞染色体进行核型分析.研究表明,早熟猫尾草染色体数为2n=28,染色体的核型为K(2n)=2n=4x=28=22m+4sm(SAT)+2st(SAT),其中第5、11对染色体为近中部着丝粒染色体,第8对染色体为亚端部着丝粒染色体,其余各对染色体为中部着丝粒染色体,第8对染色体携带随体;晚熟猫尾草染色体数为2n=42,染色体的核型为K(2n)=2n=6x=42=2M+24m+14sm+2sm(SAT),其中第3、4、6、11、12、13、14、20对染色体为近中部着丝粒染色体,第18对染色体为正中部着丝粒染色体,第22号为B染色体,其余各对染色体为中部着丝粒染色体,第11对染色体携带随体.早熟与晚熟猫尾草都属2A核型.     

库拉索芦荟染色体核型分析

对库拉索芦荟(Aloe vera[L.]Burm.f)细胞染色体进行了核型分析,染色体类型按Levan方法分类.研究表明,库拉索芦荟染色体数为2n=14.染色体的核型为K(2n)=2x=6sm 6st 2m.其中第2,3,4对染色体为亚端部着丝粒染色体,第1,5,6对染色体为亚中部着丝粒染色体,第7对染色体为中部着丝粒染色体,在所有7对染色体中未观察到有携带随体的染色体存在.     

中国水蛇和铅色水蛇染色体组型的比较研究

本文报道福州近郊的中国水蛇和铅色水蛇的染色体组型比较研究的结果.两种蛇的染色体数目均为2n=36,其中8对为大染色体,10对为小染色体,各对染色体的相对长度和臂比指数相似.二者的第1、3、6对为中间着丝点;第2对为近中间着丝点;第5对为近端着丝点;第7、8对为端着丝点;第4对均为性染色体.雄性染色体二倍体同型为ZZ,雌性染色体二倍体异型为ZW,Z为中间着丝点,W为近端着丝点,并且与Z染色体接近同样大小.因此,两种蛇的染色体组型基本相同.这说明水游蛇亚科的水蛇属与游蛇亚科的某些种在性染色体的分化上及其染色体组型,均有相似之处.     

翘嘴鲌染色体核型分析及遗传学特性研究

对翘嘴鲌(Erythroculter ilishaeformis)肾细胞染色体的核型进行了分析.核型分析结果表明,翘嘴鲌的肾细胞染色体组是由48条染色体组成,染色体组型按着丝粒位置可分为四组,分别是中部着丝粒染色体、亚中部着丝粒染色体、端部着丝粒染色体.其中中部着丝粒染色体9对,亚中部着丝粒染色体5对,亚端部着丝粒染色体9对,端部着丝粒染色体1对,每对染色体均由二条同源染色体组成.这些研究结果表明,翘嘴鲌是一种二倍鱼,其染色体数目为2n=48,核型公式为2n=18m+10sm+18st+2t ,NF=76.     

红花(Carthamus tinctorius)染色体组型分析

本实验是应用植物有丝分裂染色体标本制备的新方法,观察了红花的染色体形态、数目以及结构特征,从而进行了染色体组型的初步分析,并对红花染色体的有关特点进行了讨论.红花染色体为2n=24,可配为12对,其中5对为中部着丝点染色体.6对为亚中部着丝点和一对在短臂具随体染色体.     

优雅蝈螽细胞减数分裂期染色体行为的观察

本文以螽斯精巢为实验材料,经过低渗、固定、压片、空气干燥、改良品红染色制备染色体标本,对优雅蝈螽减数分裂染色体行为进行了研究.结果 :优雅蝈螽精巢细胞染色体2n♂=31,染色体几乎全部为近端部着丝粒染色体,其性别决定机制为:XO为雄性,XX为雌性.减数分裂双线期同源染色体形成环状或8字状,端部交叉的结构.     

鱼腥草染色体核型分析

用去壁低渗染色体制片方法,对鱼腥草腋芽细胞染色体制片,研究其染色体组型,结果表明:鱼腥草为二倍体、染色体数目为22;染色体核型公式为2n=2x=22=10m 10sm 2t,第1、3、4、6、7号染色体为中间着丝点染色体,第2、5、8、9、10号染色体为近中着丝点染色体,第11号染色体为端部着丝点染色体,单倍染色体数为11;该染色体组内最长与最短染色体长度比值为3.73,臂比大于2:1的染色体为5、10、11号,共3对,占该基因组内染色体总数的27.3%,故鱼腥草的核型为2B型.     

条纹斑竹鲨染色体的核型分析

采用PHA结合秋水仙素活体注射,取条纹斑竹鲨(Chiloscyllium plagiosum)脾脏经低渗处理,空气干燥制片法制作染色体标本,对染色体进行Giemsa染色,完成条纹斑竹鲨染色体核型分析.研究结果表明,条纹斑竹鲨的染色体组由20对中部着丝粒染色体、12对亚中部着丝粒染色体、5对亚端部着丝粒染色体和14对端部着丝粒染色体构成,染色体核型公式为:2n=102=28t 10st 24sm 40m,染色体臂数NF=166,其中1对亚中部着丝粒染色体带有明显的次缢痕.与其他软骨鱼类相似,条纹斑竹鲨同样具有数目众多的染色体二倍体数,但以中部着丝粒和亚中部着丝粒染色体为主.     

离子注入水稻细胞学效应研究

以水稻品种紫粳二倍体和四倍体为实验材料,以低能氮离子束为诱变源,研究了离子束诱变对水稻根尖细胞染色体的影响.结果发现,低能离子束注入引起了水稻根尖分生区细胞有丝分裂异常,出现许多染色体畸变类型,包括后期染色体桥、落后染色体、染色体断片、中期染色体单价体等.染色体畸变率并不是随着剂量的增加呈现直线上升的趋势,而是有一定的...     

新发现的毛冠鹿的一核型与性染色体探讨

以原代培养和传代培养的方法培养成年雄性毛冠鹿的皮肤细胞,对其核型进行分析,发现了一种新的核型,二倍体染色体数为2n=48,染色体正好配成24对,其中有一对为异型染色体.该对异型染色体的一条为较大的端着丝粒染色体,长度仅次于第3号染色体,C带与薄层扫描显示其异染色质丰富.另一条为较大的近端着丝粒染色体,长度介于第2号与第3号染色体之间,比其他已知核型中相应的染色体长,几乎全为异染色质.G带分析表明该对异型染色体的异染色质区域均显示一些数目不等的浅带.本文通过核型分析,对毛冠鹿的性染色体进行了初步的探讨.     

七星瓢虫精母细胞减数分裂观察研究

研究昆虫染色体一般选择在生殖细胞减数分裂阶段.七星瓢虫初级精母细胞的染色体计数为2n=16+X,减数分裂中期,n=8、n=8+X,染色体形态多为短棒状(参见照片).其性染色体是属XD型,雌性XX,为同配性别,雄性为异配性别,即X0(2n—1).昆虫染色体数量、组型,以及减数分裂的配对情况均与分类学亲缘关系有相关性,是昆虫正确鉴定和系统分类的重要参考.     

In the platypus a meiotic chain of ten sex chromosomes shares genes with the bird Z and mammal X chromosomes

Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males, or of both sexes, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants and insects but are rare in vertebrates. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades. Here we demonstrate that platypus have five male-specific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes). These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. Which, if any, of these sex chromosomes bears one or more sex-determining genes remains unknown. The largest X chromosome, with homology to the human X chromosome, lies at one end of the chain, and a chromosome with homology to the bird Z chromosome lies near the other end. This suggests an evolutionary link between mammal and bird sex chromosome systems, which were previously thought to have evolved independently.     

Study on the sex-related AFLP marker of the Yangtze finless porpoise

The sex-related molecular marker of the Yangtze finless porpoise was screened using Amplified Fragment Length Polymorphism （AFLP） technique combined with the bulked segregant analysis. Totally 36 AFLP primer combinations were used to detect the genome DNA bulks of the female and male porpoises, and one sex-related AFLP marker was finally obtained. The marker can be applied to sex identification, and provides a base for further cloning of sex-related genes and analyzing of Y chromosome haplotypes of the Yangtze finless porpoise.     

Repetitive DNA sequences from the X chromosome of the spiny eel (Mastacembelus aculeatus)

To investigate the characters of repetitive DNA sequence in the sex chromosomes of the spiny eel (Mastacembelus aculeatus), the X chromosomal library was screened and a family of repetitive sequence, consisting of Ma 1-Ma 6, was isolated. The fluorescence in situ hybridization (FISH) result confirmed that Ma 1 - Ma 5 dispersed over sex chromosomes and all autosomes, whereas, Ma 6 is sex chromosome-specific and distributed only on the C-band positive regions of X chromosome, and Ma 6 maybe the main components of the heterochromatic regions of X chromosome. This study provides additional information about the evolution of sex chromosomes in lower vertebrates such as fish.      

A primitive Y chromosome in papaya marks incipient sex chromosome evolution

Many diverse systems for sex determination have evolved in plants and animals. One involves physically distinct (heteromorphic) sex chromosomes (X and Y, or Z and W) that are homozygous in one sex (usually female) and heterozygous in the other (usually male). Sex chromosome evolution is thought to involve suppression of recombination around the sex determination genes, rendering permanently heterozygous a chromosomal region that may then accumulate deleterious recessive mutations by Muller's ratchet, and fix deleterious mutations by hitchhiking as nearby favourable mutations are selected on the Y chromosome. Over time, these processes may cause the Y chromosome to degenerate and to diverge from the X chromosome over much of its length; for example, only 5% of the human Y chromosome still shows X-Y recombination. Here we show that papaya contains a primitive Y chromosome, with a male-specific region that accounts for only about 10% of the chromosome but has undergone severe recombination suppression and DNA sequence degeneration. This finding provides direct evidence for the origin of sex chromosomes from autosomes.     

我国牛科（Bovidae）中3种动物的染色体组型比较分析

比较分析我国牛科中３种动物（即羚牛、绵羊、黄牛）的染色体组型，从染色体数目和形态上比较它们之间的差异，并讨论这３种动物彼此之间的进化亲缘关系和进行杂交育种的可能性，为畜牧育种培养新类型提供细胞遗传学的依据。     

Population structure of the human pseudoautosomal boundary

The mammalian sex chromosomes are composed of two genetically distinct segments: the pseudoautosomal region, where recombination occurs between the X and Y chromosomes, and the sex chromosome-specific parts. Between these two segments the human sex chromosomes differ by the insertion of an Alu element on the Y chromosome. We have surveyed the sequence variation in the boundary region using the polymerase chain reaction. Fifty seven Y and sixty X chromosomes from ten different human populations were analysed. The X chromosomes were found to be polymorphic at five positions in a 300-base-pair region. By contrast, all Y chromosomes were identical except for one distal polymorphism shared with the X chromosome.     

葎草单染色体的显微分离及DOP-PCR技术体系建立

葎草是具有XX/XY1Y2性染色体系统的雌雄异株植物,是研究植物性染色体演化的模式材料之一.利用染色体显微分离技术从葎草根尖有丝分裂中期分裂相中将单条染色体进行了显微分离及DOP-PCR(Degenerate oligonucleotide primer-PCR)扩增,并构建了单染色体DOP-PCR扩增产物的荧光探针,对葎草根尖有丝分裂中期分裂相染色体进行了荧光原位杂交,其结果表明荧光信号分布在所有的染色体上,表明所建立的技术体系能够成功分离葎草单染色体并进行DNA扩增.本研究结果为进一步进行葎草X,Y染色体的细胞及分子生物学研究提供了技术支持.     

青鲫(♀)×兴国红鲤(♂)杂交F1代染色体数目及组型分析

采用肾细胞染色体直接制片法及Levan提出的标准,对青鲫(♀)×兴国红鲤(♂)杂交F1代染色体数目及组型分析表明:此杂交F1代鱼的肾细胞染色体数目为150条.染色体组型按着丝点位置可分为四组,其中中部着丝粒染色体9条,亚中部着丝粒染色体15条,亚端部着丝粒染色体78条,端部着丝粒染色体48条.每个染色体小组均由3条同源染色体组成,表明此杂交鱼为三倍体,核型公式为3n=9m 15sm 78st 48t.臂数NF=174.     

Genetic evidence that a Y-linked gene in man is homologous to a gene on the X chromosome

The mammalian sex chromosomes are thought to be related to each other by sharing a common origin. That is, the X and Y chromosomes originally evolved from a pair of chromosomes that only differed at the locus determining sexual differentiation. For example, this evolutionary relationship is reflected during meiosis in chromosomal pairing between the tip of the human X chromosome short arm and the Y chromosome which presumably implies sequence homology. However, compelling genetic evidence for functional homology between the mammalian X and Y chromosome is lacking. We describe here the localization of a gene to the tip of the short arm of the human X chromosome and evidence for a related gene on the Y chromosome.