“琼花”的染色体研究

本文对两种类型“琼花”小孢子母细胞(花粉母细胞)减数分裂和芽尖体细胞有丝分裂进行了观察。结果表明,两者具有相同的染色体数目,2n=2x=18,並且两者的核型组成也相同。2对最大的染色体和4对较小的染色体为具中部着丝点染色体,1对较大的染色体和2对较小染色体为具近中部着丝点染色体。     

Measurement of the relations between chromosomes and behavior

The relations between the three major Drosophila melanogaster chromosomes and individual differences in geotaxis are assayed in populations selected for positive and negative geotaxis and in an unselected foundation population. The major changes which occur with selection and the differential roles in geotaxis of the three large chromosomes are described.     

薏苡不同种质的基因组原位杂交分析

为了研究薏苡属不同种质之间的关系,采用基因组原位杂交(GISH)技术,以四倍体栽培薏苡(2n=20,AABB)基因组总DNA作为探针,分别对广西的栽培薏苡、野生薏苡和水生薏苡体细胞中期染色体进行基因组原位杂交。杂交结果显示,栽培薏苡和野生薏苡染色体都被强烈而密集的杂交信号所标记,说明野生薏苡与栽培薏苡在基因组染色体水平上的同源程度很高,保守重复序列占很大比重;水生薏苡的基因组中有20条染色体的DNA成分与栽培薏苡的基因组DNA高度同源,推断供试的水生薏苡种属于广西六倍体水生薏苡居群。     

多疣狭口蛙核型分析

对采自云南省昆明市西南林学院校园的多疣狭口蛙进行染色体核型分析,结果为:2n=28,NF=56,可配成14对同源染色体,由4对大型染色体和10对小型染色体组成;两性间未发现异型性染色体.将本次研究结果与已有的狭口蛙属及姬蛙科其他属的染色体资料比较分析,狭口蛙属4个种第3对染色体均为亚中着丝粒染色体,且长臂次缢痕在第5对染色体上都出现,可以认为是分类学上狭口蛙属核型区别于姬蛙科其他属的有意义的指标.     

人类人工染色体(HACs)研究进展

人类人工染色体(HACs)由着丝粒、端粒和复制起点组成。通过对天然染色体的改造或者从头构建的方法可以获得多种类型HACs。HACs可以携带大片段基因组DNA,是建立转基因动物模型的重要手段,在基因治疗方面也有着广阔的应用前景。文章从HACs的结构及各组成元件的功能、HACs的不同构建方法、HACs在转基因研究及基因治疗中的应用等方面,对HACs的最新研究进展进行了综述,同时指出了HACs研究中存在的问题,并对HACs的应用前景进行了展望。     

一个枇杷(Eriobotrya japonica L.)不育突变植株的细胞学观察

观察了一个楷杷(Eriobotrya japonica L.)不育突变植株的花粉母细胞减数分裂行为与花粉的育性,有如下异常现象:(1)第一次分裂的终变期,见部分母细胞有2～4个不联会或联会不紧密的染色体,因而出现若干单价体;(2)中期Ⅰ常见一些染色体提早分离;(3)后期Ⅰ一些母细胞出现落后染色体,后期Ⅱ亦见到一些落后染色体或呈多极分离;(4)四分孢子期,小孢子的发育常不整齐,有的呈小枝状态,有少量异常多分体出现;(5)花粉粒的大小不一,有一些巨大型花粉和大量败育花粉,花粉发芽率低,且不甚正常。根据如上观察结果,认为是一个自然发生的不联会突变,作为育种的原始材料,具有一定价值。     

Polyteny: A Source of Cryptic Speciation among Copepods

A large form of the copepod Pseudocalanus is found in two warm, semi-landlocked fiords in arctic Canada, together with a similar but smaller form attributable to the widespread P. minutus. The large form has the same chromosomne number as P. minutus, but has larger chromosomes and a higher nuclear DNA content. There are suggestions in the literature that other similar polytenic and cryptic species occur among copepods.     

三种百合科植物的染色体核型分析

本文报道了产于浙江和安徽的三种百合科(Liliaceae)植物的染色体数目和核型:天门冬Asparagus Cochinchinensis,2n=20(2X)=8m 12sm;萱草Hemerocallis fulva,2n=33(3x)=21m 6sm 3st十3t和多叶韭Allium plurifoliatum,2n=32(4X)=24 m 8 sm。并讨论了它们的核型特点及与近缘种的关系,其中天门冬和多叶韭的核型为节一次报道。     

Karyomorphological Studies on Chinese Pot Chrysanthemum Cultivars with Large Inflorescences

In this paper, we reported the karyotypes of 30 Chinese large flowered pot chrysanthemum cultivars, differing with respect to flower type, petal type, and flower colour. The interphase nuclei and prophase chromosomes of all the cultivars are, respectively, of the complex chromocentre and the interstitial type. Somatic chromosome number varies from 49 to 62, mostly falling in the range 51-56 or 58. Most of the cultivars are chromosomal mosaics, with three showing 2n = 6x = 54, and two 2n ＋1= 6x ＋ 1 = 55. At mitotic metaphase, most of the chromosomes are of the metacentric or submetacentric type, with a small number of acrocentrics and telocentrics. B chromosome （s） are present in about 22% of the entireties. The asymmetry index of the chromosomes ranges between 61 and 66%. The karyotypes can be categorized as reversely symmetrical types ＂2A＂ or ＂2B＂.     

水稻穗颈维管束及产量相关性状的QTL分析

采用2个偏粳品种“光三”／C418的重组自交系群体，构建SSR标记的连锁图谱，并以此对水稻穗颈维管束数和产量相关性状进行了QTL(Quantitative Trait Loci)分析。在第1，5，8和11染色体上检测到4个控制穗颈大维管束数的QTL。在第5，9和10染色体上检测到3个控制穗颈小维管束数的QTL；共检测到产量及8个与产量相关性状的30个QTL。通过分析穗颈维管束数与穗一、二次枝梗数，穗一、二次枝梗粒数，穗粒数，结实率，单株产量QTL在染色体上的分布及连锁关系，表明穗颈维管束是影响产量的重要解剖结构；通过增加穗颈大、小维管束数可望增加水稻“库”的容量。保证“流”的畅通。     

甘肃白猪、杜洛克、汉普夏及其杂交猪的染色体研究

通过对甘肃白猪、杜洛克、汉普夏及其杂交猪的群体细胞遗传学研究,发现在染色体组型特征上,甘肃白猪同杜洛克、汉普夏的差异较大,但同长白猪、苏白猪的差异较小;在甘肃白猪的两大地方类群中,临夏类群第8对染色体上次缢痕出现的频率高于武威类群。经过比较分析,可以肯定临农、武白、武民三个品群的遗传性基本稳定;染色体的研究完全有希望来预测杂种后代优势率的高低,即染色体的杂合性同杂种优势率有一定的相关性。     

斑腿蝗科两种短翅蝗虫的染色体研究

斑腿蝗科两种短翅蝗虫,昆明拟凹背蝗和绿胫舟形蝗的染色体数目相同,均为2n(♂)=23,全部是端部着丝点染色体,性别决定机制XO型,性染色体X属于大型染色体,相对长度位居第一.研究结果表明:昆明拟凹背蝗的染色体C带共28条,除着丝粒带之外,其余5条为端带,分别出现于L2,M5,M7,M8和S11.两种短翅蝗虫的减数分裂染色体交叉频率以1位点和2位点的交叉居多.     

黑白花奶牛染色体核型,带型初步分析

利用外周血淋巴细胞的培养方法,我们研究了黑白花奶牛的染色体核型和G带,研究结果表明,黑白花奶牛的染色体2~n=60,其中29对为常染色体,而另一对为性染色体。全部常染色体为端着丝点。性染色体中的X染色体为大的亚中着丝点染色体,Y染色体为小的亚中着丝点染色体。对黑花奶牛的染色体G带也作了分析和详细的描述。     

A physical map of the 1-gigabase bread wheat chromosome 3B

As the staple food for 35% of the world's population, wheat is one of the most important crop species. To date, sequence-based tools to accelerate wheat improvement are lacking. As part of the international effort to sequence the 17-billion-base-pair hexaploid bread wheat genome (2n = 6x = 42 chromosomes), we constructed a bacterial artificial chromosome (BAC)-based integrated physical map of the largest chromosome, 3B, that alone is 995 megabases. A chromosome-specific BAC library was used to assemble 82% of the chromosome into 1036 contigs that were anchored with 1443 molecular markers, providing a major resource for genetic and genomic studies. This physical map establishes a template for the remaining wheat chromosomes and demonstrates the feasibility of constructing physical maps in large, complex, polyploid genomes with a chromosome-based approach.     

Recurring origins of allopolyploid species in asplenium

A large proportion of plant species has originated through allopolyploidy: interspecific hybridization followed by chromosome doubling. Heterozygosity remains fixed in allopolyploids because of nonsegregation of parental chromosomes. Two allotetraploid species of the fern genus Asplenium show allozyme polymorphisms at loci that are polymorphic in their diploid progenitors, indicating that each has originated more than once and implicating continued gene flow from diploids to tetraploids.     

木耳菜染色体制片优化及核型分析

【目的】优化木耳菜Basella alba染色体制片条件,并了解其核型特征,为今后研究不同类型木耳菜的亲缘关系和系统进化提供理论基础。【方法】以木耳菜品种‘大叶木耳菜’为材料,对影响染色体制片效果的取材部位、预处理时间和解离时间等条件进行优化,并进行核型分析。【结果】木耳菜主根根尖的分裂相细胞和中期分裂相细胞比例最多;0.002 mol·L-1的8-羟基喹啉预处理6 h,木耳菜染色体收缩性最好,形态最佳,分散性好;在60℃下1mol·L-1的HCl解离8 min,木耳菜染色体着色良好且细胞质透明,对比度高。木耳菜的核型公式为2n=2x=44=38m(2SAT)+6sm,染色体相对长度组成为20 M2+22 M1+2 S,染色体长度比为1.93,染色体相对长度变化范围为3.13%~6.06%,着丝粒指数变化范围为35.19%~47.86%,臂比值变化范围为1.09~1.84,第10、16、17对染色体为近中部着丝粒染色体,其余均为中部着丝粒染色体,第13对染色体具有随体,木耳菜核型不对称系数为57.89%,核型按分类标准属1A型。【结论】明确了木耳菜染色体制片的最佳条件参数,并从细胞遗传学角度揭示了木耳菜的核型特征。     

冬小麦1A缺体单倍体的细胞学研究

对1B/1R易位系冬小麦73(36)9-1的1A缺体单倍体小孢子母细胞和小孢子进行了细胞学观察,结果表明:①减数分裂有双线期,76.7％细胞的全部染色体都有不同形态的双线结构,而中期Ⅰ染色体配对的细胞只有41％;②末端联会较多,并靠联会较少,其分布随每个细胞二价体数目的增加而逐渐减少;③四分体时期有大量的二分体,一分体和三分体,它们进一步发育成大量的败育小孢子和少量异常小孢子;④中期Ⅰ和小孢子中有不同频率的融合细胞。     

Chromosomal region of the cystic fibrosis gene in yeast artificial chromosomes: a model for human genome mapping

A general strategy for cloning and mapping large regions of human DNA with yeast artificial chromosomes (YAC's) is described. It relies on the use of the polymerase chain reaction to detect DNA landmarks called sequence-tagged sites (STS's) within YAC clones. The method was applied to the region of human chromosome 7 containing the cystic fibrosis (CF) gene. Thirty YAC clones from this region were analyzed, and a contig map that spans more than 1,500,000 base pairs was assembled. Individual YAC's as large as 790 kilobase pairs and containing the entire CF gene were constructed in vivo by meiotic recombination in yeast between pairs of overlapping YAC's.     

三结合育种方法在小麦优异种质创育中的应用

为创建新型的小麦基因体系,并为性状改良和新品种选育提供丰富的种质资源,利用远缘杂交、多倍体育种和电离辐射三结合的育种方法,进行了37 a的小麦超亲遗传及新种质创育工作。结果表明,三结合育种后代品系的染色体数量变异和结构变异幅度大,趋向双亲性状类型的分离较少而超亲遗传突出,后代种质分离持续时间长,不少具有较好的综合性状,籽粒产量和品质较常规育种后代显著提高。研究证明,三结合育种方法既克服了单纯的远缘杂交、多倍体育种或辐射育种方法的缺点,又综合了它们的优点,为丰富小麦种质资源和提高小麦育种效率开辟了一条新途径。     

拟水狼蛛染色体的初步观察

以附肢形成之前的蜘蛛胚胎细胞为材料,经秋水仙素处理、纸渗、固定、制片及染色,对拟水狼蛛的体细胞染色体进行了初步观察．结果表明：拟水狼蛛的染色体数为：雄性２ｎ＝２６,雌性２ｎ＝２８,性别决定机制为Ｘ１Ｘ２Ｏ．Ｃ－带分析表明,所有染色体都为端着丝粒染色体,端部有特异性染色质存在．