家蚕三种染色体组型的比较分析

本文比较了家蚕三个不同品种的卵母细胞联合复合体组型、减数分裂染色体组型及雌蚕体细胞有丝分裂染色体组型.结果发现,三种组型的染色体相对长度无显著差异.据此提出家蚕三种组型能以有丝分裂组型为基准,互相参照比较.对雌蚕的异型性染色体及其在减数分裂中的配对行为进行了讨论.     

家蚕粗线期染色体核型模式的建立

家蚕染色体核型分析是研究家蚕遗传、变异和基因定位等的重要方法之一。用Luc ia染色体分析软件对家蚕品种大造卵母细胞粗线期染色体的长度和染色粒分布情况作了调查,结果表明:不同细胞的染色体总长度差异较大,同一细胞内各染色体绝对长度也互不相同,而且不同细胞相同序号染色体之间的长度差异也很大,但不同细胞相同序号染色体的相对长度比较接近,差异较小,适合作为建立核型模式的参数。对家蚕粗线期染色体的染色粒分析表明:染色粒在整个染色体群的各条染色体中含量均较高,染色粒相对长度在1%~3%之间的染色体比例最大。综合4种参数,建立了一个家蚕粗线期染色体的核型模式图,初步反映粗线期每条染色体各自的特征。     

苏州樗蚕染色体观察

本文对苏州蚕专校园内楼息的樗蚕,进行了细胞学观察,结果在雌蚕卵原细胞有丝分裂中期,看到26条呈短杆状的染色体,在卵母细胞减数分裂双线期看到13对平行接合的二价染色体,由此,可判定该地樗蚕的染色体为2n=26,n=13,由于在双线期未发现单价体,故推定其性型为XX—XY型。关于其生物学性状及核型分析,拟待另报。     

家蚕有丝分裂染色体研究

以家蚕品种Y1000、Y2000的早期胚胎（蚕卵）为材料，空气干燥法制片，得到具一定长度和缢痕为特征的胚胎体细胞早中期染色体，并对其进行相对长度计算和核型分析。经对23个分散好、完整的分裂相的分析表明：家蚕早期胚胎（蚕卵）有丝分裂早中期染色体中有异型性染色体存在，Z染色体是核型中最长的，通常具有亚端和亚中部次缢痕，W染色体很短，约相当干Z染色体的1／3长。     

野桑蚕减数分裂的染色体研究

对中国和日本野桑蚕染色体进行了观察、研究 ,比较了中国野桑蚕卵母细胞和精母细胞减数分裂前期Ⅰ染色体的形态行为 ,发现这些差异与雌雄蚕染色体是否发生交叉是一致的 ;同时在两个地区的雌蚕粗线期均发现了末端分开呈不对称的“Y”字二价体或提前分离的二价染色体 ,对其形成机理进行了探讨     

绢丝昆虫柳天蚕细胞遗传学的研究

本文利用改良空气干燥制片法,首次对柳天蚕(Actias Selene Hubner)的染色体数目、形态及减数分裂过程进行了研究。结果表明,柳天蚕雌雄染色体数目均为n=31,呈颗粒状。其性型为xx-xy(或zz—zw)型。在双线期及终变期,雄比雌具有更为明显的交叉现象。继而对雌双线期染色体的绝对长度、相对长度进行了测算,结合染色粒等指标,初步进行了雌蚕组型排列,并得出了柳天蚕雌双线期染色体组型的雏型,对于开辟野蚕类的核型研究,充实蚕类细胞遗传学内容,具有一定的意义。     

老芒麦染色体组型分析

以老芒麦种子为材料,利用酶解-火焰干燥法来分析有丝分裂中期染色体核型,为老芒麦系统分类及育种工作提供科学依据。研究结果表明,老芒麦染色体数目为28条,13号染色体上有1对随体,臂比值大于2的染色体占7.14%,最长染色体与最短染色体比值为2.04,核型公式是2n=4x=28=24m+4sm(2SAT),不对称类型为2B。细胞有丝分裂呈现出间期、前期、前中期、中期、后期5个不同的时期。在分裂间期,细胞核染色均匀;到分裂前期时可以看到纤细状的网状染色体;进入分裂前中期,可辨别单个染色体;到分裂中期,染色体高度浓缩,姊妹染色单体及着丝点都清晰可辨;在分裂后期,姊妹染色单体分离。     

家蚕核仁和核仁染色体的初步研究

在家蚕的染色体制片中.以精巢为材料,采用涂片.Giemsa染色法,对一代杂种苏5×苏6的核仁和核仁染色体进行了观察和分析.结果表明,在间期细胞核内.大多数有一个核仁,少数有两个或三个核仁.在减数分裂粗线期至终变期的细胞核内,有一个核仁和三条贴附在核仁上的核仁染色体,这三条核仁染色体分别是第2号、第5号和第22号.有丝分裂中期的细胞核内未见核仁,但至少观察到四条染色体有明显的缢痕(Chromosome constriction),它们是两对与核仁形成的有关的核仁染色体.其他染色体均呈短杆状,未见明显缢痕.     

藏鸡的有丝分裂观察及染色体核型分析简

试验采用直接骨髓法制备林芝藏鸡染色体,通过显微自动成像系统观察藏鸡细胞有丝分裂全过程,包括间期、早前期、前期、中期、后期和末期,并分析了藏鸡有丝分裂过程染色体的形态变化规律。通过比较有丝分裂各期的形态,结果发现藏鸡有丝分裂的前期染色体伸展最长,碱基暴露最多,适合于做基因定位工作。同时进行了藏鸡染色体的核型分析,数据统计结果发现林芝地区藏鸡染色体数目2n=78,其中前5对染色体和性染色体中有3对中央着丝粒（m）染色体、1对近中着丝粒（sm）染色体、2对端着丝粒（t）染色体。与前人试验结果进行了比较,结果显示存在一定差异,原因仍需进一步试验验证。     

盐穗木的染色体数目与核型分析

盐穗木（Halostachys caspica）是新疆荒漠盐碱地常见的盐生植物。本研究以盐穗木萌发种子的根尖为材料,采用常规压片法对根尖细胞有丝分裂中期染色体进行数目统计及核型分析。结果表明,盐穗木体细胞染色体数目为2x=18条,染色体核型模式为2n=2x=18m,4号染色体含两个随体（SAT）,属于1A染色体核型。     

红球姜核型分析

为了对红球姜(Zingibe zerumbet)的染色体进行识别,并对该物种基因组的结构进行初步研究,利用PI和DAPI组合(CPD)染色与45SrDNA探针荧光原位杂交对中期染色体进行了分析。结果显示,红球姜具有2对45SrDNA位点,分别位于第5号和第10号染色体的短臂,对应于相应染色体上的显著CPD带区。基于rDNA位点和染色体测量数据,建立了红球姜准确而详细的分子细胞遗传学核型。     

山西白羊草染色体核型分析

选用山西白羊草(Bothriochloa ischaemum)种子为材料,采用根尖压片法进行细胞染色体核型分析,为白羊草的种质资源利用及育种提供细胞学依据。观察统计了30个完整的中期分裂相确定染色体数目,并选其中5个分裂相进行核型分析。结果表明,白羊草染色体数为2n=40,核型公式为K(2n)=4x=40=34m+6sm,其中中部着丝粒染色体(m)为17对,近中部着丝粒染色体(sm)为3对,核型类型为1B。核型不对称系数为58.32%。     

Fine Structure of Spermatogonia and Spermatocytes in the Rlue Fox (Alopex Lagopus)

The ultrastructural features, characterizing the different types of spermatogonia and spermatocytes in the blue fox, have been studied within and near the reproductive season, and also in the summer and autumn.Two distinct types of spermatogonia — A and Β — are described. The A-spermatogonia often have a prominent nucleolus and numerous cytoplasmic organelles including characteristic whorls of AER. Large vacuoles containing electron dense particles are sometimes observed. In the B-spermatogonia the chromatin forms condensed areas of varying size, and the nucleolus is usually absent. The number of cytoplasmic organelles is generally small.Ultrastructural characteristics are further used to distinguish between the different stages in the prophase of the primary spermatocytes. In leptotene the nucleus contains a thread-like chromatin with electron dense peripheral areas. Towards the end of the stage the mitochondria display dilated cristae, and aggregations of a granular material can be observed in the intermitochondrial matrix. Zytogene is characterized by the appearance of syniaptinemal complexes in the nucleus, and of the chromatoid body and piles of annulate lamellae in the juxtanuclear cytoplasm. In pachytene the chromosomes become apparent as aggregations of condensed chromatin associated with the synaptinemal complexes. The Golgi complex is more prominent than in the previous stages, and the number of the other cytoplasmic organelles is increasing. In the last stages of the prophase (diplotene and diakenesis) the chromosomes become still more electron dense, the nucleolus appears as a very prominent structure, and there is a marked vesiculation of the cytoplasm.The secondary spermatocytes have a characteristic nucleus with a somewhat irregular outline and larger peripheral areas of condensed chromatin. In the cytoplasm a double Golgi complex is frequently observed.In the summer and autumn spermatocytes in zygotene seem to represent the most advanced form of spermatogenic cells.     

Representation of metaphase chromosomes of the pig (Sus scrofa dom.) in the scanning electron microscope]

The appearance of metaphase chromosomes of the pig in the scanning electronmicroscope Two karyotypes of the pig were examined, one using light-microscopy after G-band treatment and the other using scanning electronmicroscopy after BrdU treatment. In both cases the structures of the surface of the chromatids were identical.     

中国野桑蚕Giemsa淡染性染色体的研究

对来自重庆、陕西、湖北等 3个不同地域的野桑蚕染色体进行了研究 ,结果表明 3个不同地域的野桑蚕染色体数目都为n =2 8,2n =5 6 ;均在粗线期染色体观察到了与家蚕类似的Giemsa淡染性区域 ,并对其进行了组型分析 ,从细胞遗传学的角度探讨了野桑蚕与家蚕的亲缘关系。     

三份偃麦草种质的染色体核型分析

选用产地来源不同的3份偃麦草的种子为试验材料,采用根尖压片法进行细胞染色体核型分析,旨在为其细胞学特性和演化趋势的研究奠定科学基础。结果表明,来源于俄罗斯列宁格勒的偃麦草种质ER044染色体数目为2n=6X=42,染色体相对长度组成为:4L+14M₂+20M₁+4S,核型公式为:K(2n)=6X=42=2M+32m+8sm。来源于阿富汗喀布尔的偃麦草种质ER058染色体数目为2n=6X=42,染色体相对长度组成为: 2L+20M₂+16M₁+4S,核型公式K(2n)=6X=42=30m+12sm(2sat)。采自于中国新疆的偃麦草种质ER132染色体数目为2n=6X=42,染色体相对长度组成为:4L+16M₂+16M₁+6S,核型公式为:K(2n)=6X=42=32m+8sm(4sat)+2st。3份偃麦草种质的染色体核型均属于“2B”类型。     

Wapl localization on the synaptonemal complex, a meiosis-specific proteinaceous structure that binds homologous chromosomes, in the female mouse.

The wings apart-like (Wapl) protein is required to hold sister chromatids together in mitotic heterochromatin in Drosophila melanogaster. It is localized on the synaptonemal complex (SC), a meiosis-specific structure connecting one pair of sister chromatids to the homologous pair in mouse pachytene spermatocytes. The human Wapl is a cohesin-binding protein that facilitates cohesin's timely release from chromosome arms during prophase. The objective of the present study was to determine the subcellular localization of the mouse Wapl on female meiotic chromosomes at pachynema. The pachytene oocytes were isolated from foetal ovaries at 18.5 dpc and double immunostained with anti-synaptonemal complex protein 2 (SYCP2) and anti-Wapl. In the pachytene oocytes examined, mouse Wapl was colocalized with SYCP2 on the SC. Our results further implicated that Wapl might play a crucial role in meiotic chromosome remodelling at early meiosis.     

C- AND G- BANDING PATTERNS AND CHROMOSOMAL MORPHOLOGY OF SOME BREEDS OF AUSTRALIAN CATTLE

A cytogenetical study using metaphase chromosomes from cultured lymphocytes, was made of 2 Banteng (Bibos banteng) steers and 218 bulls representing 13 purebreeds (Bos taurus type, Bos indicus type and Sanga) and 7 cross-breeds. Studies were made of photographic karyotypes of Giemsa stained and C-banded chromosomes of bulls of each breed and of B-banded chromosomes from 3 breeds of Bos indicus and one cross-breed Australian Friesian Sahiwal) cattle. The relative lengths of chromosomes of Bos taurus and Bos indicus bulls were compared and significant difference in relative lengths of the X chromosomes were noted between these two species. There was a differences in morphology of the Y chromosomes; Sanga, Banteng and Bos taurus type breeds had a small submetacentric Y chromosome, except for the Jersey which had a metacentric Y chromosome. All Bos indicus type bulls had an acrocentric Y chromosome but the Droughtmaster breed had two forms of the Y chromosome (submetacentric and acrocentric). The C-banding patterns of the autosomes and X chromosomes were similar for all breeds while those of the Y chromosomes of Bos indicus type cattle allowed their accurate identification. G-banding patterns of Bos indicus resembled those of Bos taurus and enabled pairing of homologous chromosomes. Centromeres of the autosomes were unstained but those of the sex chromosomes were darkly stained.