牛蛙染色体的高分辨晚复制带

以培养的牛蛙(Rana cataesbeiana)外周血淋巴细胞为材料,采用复制带显示技术,在牛蛙染色体上获得高分辨复制带带型。早、晚复制带纹可多达526条。确定了可作为每一条染色体标记的特征性晚复制区,绘制了牛蛙的染色体高分辩晚复制带带型模式图。以前人对蛙属某些其它种晚复制区及晚复制带型为参考,对蛙属一些种间染色体同源性进行了初步分析。     

大熊猫染色体晚复制带研究

以培养的大熊猫外周血淋巴细胞为实验材料,在细胞培养终止前４ｈ加入ＢｒｄＵ（终浓度为１０μｇ／ｍｌ培养基）,对复制的染色体ＤＮＡ进行ＢｒｄＵ标记。掺入ＢｒｄＵ的染色体经吖啶橙（０．０５％）处理、紫外光照射、Ｇｉｅｍｓａ染色后,可在染色体上获得清晰的复制带纹。根据众多分裂相所显示的不同复制带型,可初步确定大熊猫每一染色体独特的晚复制带纹。在雌性个体的两个Ｘ染色体中,一条Ｘ染色体复制明显落后于另一Ｘ染色体,尤其在迟复制Ｘ染色体长臂近着丝粒区显现出较宽的晚复制带纹。     

大熊猫染色体腹复制带研究

以培养的大熊猫外周血淋巴细胞为实验材料,在细胞培养终止前４ｈ加入ＢｒｄＵ（终浓度为１０μｇ／ｍｌ培养基）,对复制的染色体ＤＮＡ进行ＢｒｄＵ标记。掺入ＢｒｄＵ的染以体吖啶橙（０．０５％）处理、紫外光照射、Ｇｉｅｍｓａ染色后,可在染色体上获得清晰的复制带纹。根据众多分裂相所显示的不同复制带型,可初步确定大熊猫每一染色体独特的晚复制带纹。在雌性个体的两个Ｘ染色体中,一条Ｘ染色体复制明显落后于另一Ｘ染色体     

植物染色体G-带的初步研究

本文首次报道了川百台(Lilium davidii)、华山松(Pinus armardii)和七叶一枝花(Paris polyphylla)等植物染色体G-带研究结果。本试验的G-带与以往的C-带不同,C-带每条染色体上一般只有1-4条带,多分布在着丝点附近,而G-带则多达几十条,分布在整条染色体上,带纹清晰,前期染色体带呈颗粒状,中期染色体呈明显的带状,与哺乳动物染色体G-带很相似。G-带的数目取决于染色体浓缩的程度。前期染色体带纹数目是中期的三倍,接近人类高分辨带水平。对G-带带纹采用了自动光谱分析,波峰数值与带纹相符。作者同时介绍了胰酶法在植物染色体G-带中的应用。认为此方法既适合动物亦适用于植物。但植物G-带显示的关键可能不在胰酶法本身,而在合适的分裂时期及染色体处理技术。     

黑麦减数分裂染色体Giemsa显带

近年来,国际上在植物遗传学和细胞学的各个领域中广泛开展了染色体Giemsa显带技术的研究和应用,积累了大量资料,但是,迄今大量的研究工作都集中在体细胞染色体的显带方面,而花粉母细胞染色体的显带,仅在黑麦、小黑麦、Anemone blanda等少数植物上进行过研究。 国内植物染色体显带研究,近年来在黑麦、洋葱、蚕豆、小黑麦、小麦、大麦、玉米等一些植物上进行了体细胞染色体的显带研究,而在玉米上还进行了花粉母细胞染色体的显带研究。 我们曾进行过黑麦体细胞染色体Giemsa显     

植物染色体高分辨G-带技术研究

本文对植物染色体高分辨 G-带技术进行了比较系统的研究,并首次运用改良的尿素法在野生一粒小麦、玉米、蚕豆、吊兰、川百合等多种植物上诱导出 G-带,带纹清晰,数目多,分布在染色体全长上。前期染色体带呈颗粒状,中期染色体呈明显带状,与哺乳动物染色体 G-带很相似。G-带的数目取决于染色体浓缩程度,中期染色体一条深带到晚前期可显示出2.67条亚带。作者同时比较了胰酶法与尿素法的显带效果。认为两种方法显示的带纹基本相同,尿素法比胰酶法作用温和,显带时间长达数分钟,易于掌握,重复性高,具有更高的应用价值。     

大熊猫与黑熊显带染色体的比较研究

以体外培养的大熊猫（Ａｉｌｕｒｏｐｏｄａｍｅｌａｎｏｌｅｕｃａ）与黑熊（Ｓｅｌｅｎａｒｃｔｏｓｔｈｉｂｅｔａｎｕｓ）外周血淋巴细胞为实验材料,应用ＢｒｄＵ复制带显示技术,研究了大熊猫和黑熊染色体晚复制带带型。通过对大熊猫与黑熊显带染色体带型的比较,发现黑熊部分具端着丝粒的染色体与大熊猫部分具中,亚中,或亚端着丝粒的染色体的整个短臂或整个长臂有明显的带型相似性,在黑熊具中,亚中着丝粒染色体中,仅３３     

芥蓝和结球甘蓝染色体组型及C-带带型的研究

本文用改进的染色体标本制片技术,研究了芥蓝和结球甘蓝的染色体组型和 C-带带型。两种植物的二倍体均由4对中着丝粒、5对亚中着丝粒染色体组成,其中一对为随体染色体。芥蓝和结球甘蓝具有统一的染色体组型公式:2n=18=8m+10sm(2SAT),但两者的某些染色体在编号顺序上有差异。在结球甘蓝中观察,到4种不同形态的随体。用 BSG C-带方法得到 C-带带型,带型公式,芥蓝为2n=18=CITS 型=10C+2CI_++4CT~++2CS;结球甘蓝为2n=18=CITS 型=8c+2CI_++6CT~++2CS。某些带纹具多态性和杂合性。本文从染色体水平上讨论了芥蓝与甘蓝的亲缘关系。     

向日葵染色体Giemsa C-带带型分析

采用HKG(HCl-KOH-Giemsa)法对内葵杂3号三交种染色体进行了C-分带研究和分析。结果表明:每条染色体至少都有一条C-分带,染色体组共有62条C-分带,以中间带和着丝点带为主,中间带主要分布在染色体短臂上;C-分带强弱差异明显,其中46条强带,16条弱带。Giemsa C-分带带型公式为:2n=2x=34=8I++3T++5I+I+T++4C+2CI+4CI++3CI++I+T++CT++2CT+。每条染色体都显示出显著的带纹特征,因此,利用Giemsa C-分带方法可以将向日葵的每条染色体区分开。     

植物染色体G—带的研究进展

染色体 G-带技术在动物和人类遗传学中已得到了广泛应用,可是在植物方面由于它仅能显示带纹很少的 C-带、N-带或 Q-节,这就大大限制了染色体显带技术在植物细胞遗传学研究和植物育种上的进一步应用。近十年来,植物染色体 G-带的研究越来越受到人们的重视,世界上,尤其是我国有不少学者进行了详细研究,并取得了不少进展,本文仅就这方面的研究现状做一简述。     

小鼠单卵裂球体外培养及染色体制备

为了探索研究了植入前胚胎染色体病（包括平衡易位）诊断的可行性方法,作者进行了单卵裂球体外培养、染色体制备及显带技术研究,在Ｂ２培养基加血清进行培养的基础上,比较了在两种没处理因素进行体外培养时小鼠单卵裂球增殖情况,Ｂ２培养基加血清再加输卵管包埋进行培养,其单卵裂球体外增殖率为５０％（８７／１７４）,单卵裂球染色体制备成功率为２７．６％;Ｂ２培养基加腹水过滤液进行培养,其单卵裂球体外增殖率为３３％（     

Uptake of isolated plant chromosomes by plant protoplasts

For mass isolation of plant metaphase chromosomes, cultured cells of wheat (Triticum monococcum) and parsley (Petroselinum hortense) were synchronized by hydroxyurea and colchicine treatment. This synchronization procedure resulted in high mitotic synchrony, especially in suspension cultures of parsley in which 80% of the cells were found to be at the metaphase stage. Mitotic protoplasts isolated from these synchronized cell cultures served as a source for isolation of chromosomes. The described isolation and purification method yielded relatively pure chromosome suspension. The uptake of the isolated plant chromosomes into recipient wheat, parsley, and maize protoplasts was induced by polyethylene-glycol treatment. Cytological studies provided evidences for uptake of plant chromosomes into plant protoplasts.Abbreviations PEG polyethylene glycol - HU hydroxyruea - C colchicine - HUC hydroxyurea and colchicine - CIM chromosome isolation medium - TCM Tris chromosome medium     

A cytogenetic view of sex chromosome evolution in plants

The recent origin of sex chromosomes in plant species provides an opportunity to study the early stages of sex chromosome evolution. This review focuses on the cytogenetic aspects of the analysis of sex chromosome evolution in plants and in particular, on the best-studied case, the sex chromosomes in Silene latifolia. We discuss the emerging picture of sex chromosome evolution in plants and the further work that is required to gain better understanding of the similarities and differences between the trends in animal and plant sex chromosome evolution. Similar to mammals, suppression of recombination between the X and Y in S. latifolia species has occurred in several steps, however there is little evidence that inversions on the S. latifolia Y chromosome have played a role in cessation of X/Y recombination. Secondly, in S. latifolia there is a lack of evidence for genetic degeneration of the Y chromosome, unlike the events documented in mammalian sex chromosomes. The insufficient number of genes isolated from this and other plant sex chromosomes does not allow us to generalize whether the trends revealed on S. latifolia Y chromosome are general for other dioecious plants. Isolation of more plant sex-linked genes and their cytogenetic mapping with fluorescent in situ hybridisation (FISH) will ultimately lead to a much better understanding of the processes driving sex chromosome evolution in plants.     

Comparative Effects of Rye Chromosomes 1R and 5R on Androgenesis in Cultured Anthers of Wheat–Rye Substitution Lines as Dependent on the Line Origin

The effects of rye chromosomes 1R and 5R on androgenesis in cultured anthers of wheat–rye substitution lines was studied as dependent on the cultivar origin of the rye chromosomes and on the wheat genome (A or D) subjected to substitution. Chromosome 1R stimulated embryogenesis in anther cultures, while chromosome 5R suppressed it regardless of whether the corresponding wheat chromosomes were substituted in the A or D genome. The effect of chromosome 1R on embryogenesis proved to depend on its cultivar origin. Along with rye chromosome 1R, wheat chromosome 1A was shown to substantially affect total seedling regeneration. Regeneration of green seedlings was dramatically affected both by rye chromosome 1R and by wheat chromosome 1D. The results supported the published data that individual androgenesis parameters (embryogenesis, total plant regeneration, green plant regeneration) are controlled by different genetic mechanisms.     

Ring chromosomes in barley (Hordeum vulgare L.)

A plant with 2n = 14 + 1 ring chromosomes was obtained in the progeny of a primary trisomie for chromosome 7 of a two-rowed cultivar, Shin Ebisu 16. The morphological characteristics of the trisomic plants with an extra ring chromosome were similar to the primary trisomic for chromosome 7 (Semierect), which suggests that it originated from this chromosome. The ring chromosomes were not completely stable in mitotic cells because of abnormal behavior. Chromosome complements varied in different plants and in different roots within a plant. Root tip cells and spikes with 2n = 14 and 14 + 2 ring chromosomes were observed on plants with 14 + 1 ring chromosomes. Breakage-fusion-bridge cycle was inferred. The ring chromosome was associated with two normal homologues forming a trivalent in 17.6% sporocytes at metaphase I. The transmission of the extra ring chromosome was 23.1% in the progeny of the plant with 14 + 1 ring chromosomes. Trivalent formation may have been much higher at early prophase stages which were difficult to analyze in barley; only 4 of 120 sporocytes analyzed showed an isolated ring at pachytene. The ring chromosome moved to one pole without separation in 24.7% of the sporocytes at AI, and divided in 27.1% sporocytes giving rise to 8-8 separation. Only 10% of the sporocytes showed bridge formation at AI.     

Comparative effects of rye chromosomes 1R and 5R on androgenesis in cultured anthers of wheat-rye substitution lines dependending on the line origin

The effects of rye chromosomes 1R and 5R on androgenesis in cultured anthers of wheat--rye substitution lines was studied as dependent on the cultivar origin of the rye chromosomes and on the wheat genome (A or D) subjected to substitution. Chromosome 1R stimulated embryogenesis in anther cultures, while chromosome 5R suppressed it regardless of whether the corresponding wheat chromosomes were substituted in the A or D genome. The effect of chromosome 1R on embryogenesis proved to depend on its cultivar origin. Along with rye chromosome 1R, wheat chromosome 1A was shown to substantially affect total seedling regeneration. Regeneration of green seedlings was dramatically affected both by rye chromosome 1R and by wheat chromosome 1D. The results supported the published data that individual androgenesis parameters (embryogenesis, total plant regeneration, green plant regeneration) are controlled by different genetic mechanisms.     

Sex chromosomes in flowering plants

Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well-defined heteromorphic sex chromosomes are known in only four plant families. A pivotal event in sex chromosome evolution, suppression of recombination at the sex determination locus and its neighboring regions, might be lacking in most dioecious species. However, once recombination is suppressed around the sex determination region, an incipient Y chromosome starts to differentiate by accumulating deleterious mutations, transposable element insertions, chromosomal rearrangements, and selection for male-specific alleles. Some plant species have recently evolved homomorphic sex chromosomes near the inception of this evolutionary process, while a few other species have sufficiently diverged heteromorphic sex chromosomes. Comparative analysis of carefully selected plant species together with some fish species promises new insights into the origins of sex chromosomes and the selective forces driving their evolution.     

B chromosome in a rice aneuploid variation

An awned rice plant was discovered among the progeny of the triploid Zhongxian 3037. Cytological investigation showed that this awned plant was a variation with extra chromosomes. Based on the properties of the extra chromosomes during both meiosis and mitosis – e.g., short stature, darkly staining, instability in chromosome number, and lack of synapsis with A chromosomes – they could be considered to be B chromosomes in rice. The B chromosome(s) in both asexual and sexual progenies exhibited a unique segregation that is different from that of telotrisomics and other aneuploids. Moreover molecular marker analysis detected no dosage effects between the B-chromosome plant and the normal diploid of Zhongxian 3037, indicating that the B chromosomes might not be directly derived from any A-chromosome fragments in rice. Received: 8 June 1999 / Accepted: 30 December 1999     

Identification of QTLs for Yield and Associated Traits in F₂ Population of Rice

Identification of quantitative trait loci (QTLs) controlling yield and yield-related traits in rice was performed in the F₂ mapping population derived from parental rice genotypes DHMAS and K343. A total of 30 QTLs governing nine different traits were identified using the composite interval mapping (CIM) method. Four QTLs were mapped for number of tillers per plant on chromosomes 1 (2 QTLs), 2 and 3; three QTLs for panicle number per plant on chromosomes 1 (2 QTLs) and 3; four QTLs for plant height on chromosomes 2, 4, 5 and 6; one QTL for spikelet density on chromosome 5; four QTLs for spikelet fertility percentage (SFP) on chromosomes 2, 3 and 5 (2 QTLs); two QTLs for grain length on chromosomes 1 and 8; three QTLs for grain width on chromosomes1, 3 and 8; three QTLs for 1000-grain weight (TGW) on chromosomes 1, 4 and 8 and six QTLs for yield per plant (YPP) on chromosomes 2 (3 QTLs), 4, 6 and 8. Most of the QTLs were detected on chromosome 2, so further studies on chromosome 2 could help unlock some new chapters of QTL for this cross of rice variety. Identified QTLs elucidating high phenotypic variance can be used for marker-assisted selection (MAS) breeding. Further, the exploitation of information regarding molecular markers tightly linked to QTLs governing these traits will facilitate future crop improvement strategies in rice.     

Reciprocal substitutions analysis of embryo induction and plant regeneration from anther culture in wheat (Triticum aestivum L.).

Reciprocal substitutions for all chromosomes between the hard red winter wheat cultivars Wichita and Cheyenne were used to investigate the effects of individual chromosomes, as well as their interactions with the genetic background, on androgenesis. Duplicate lines for each chromosome were included to check background homogeneity. Six experiments, two for each genome, were performed. In each experiment, 14 substitution lines, their 14 duplicate lines, and the two parental genotypes ('Cheyenne' and 'Wichita') were studied. The experimental design was a randomized block with three replications. 'Wichita' and 'Cheyenne' differed significantly in embryo yield and green plant regeneration (except green plant regeneration for the B-genome tests) and were equal for albino and total plant regeneration. Embryogenesis was influenced by some chromosomes of the A, B, and D genomes; green plant production was influenced by all chromosomes of the A and D genomes except 5D; albino and total plant regeneration were affected by some chromosomes of the B and D genomes. Reciprocal effects were obtained with chromosomes 1A, 7A, 1B, 5B, 1D, and 2D for embryogenesis, chromosomes 2D and 7D for green plant regeneration, and chromosome 2D for total plant regeneration. Reciprocal substitution lines revealed reciprocal effects of homologous chromosomes, as well as interactions between substituted chromosomes and their specific genetic background.