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排序方式: 共有101条查询结果,搜索用时 31 毫秒
1.
新疆绿蟾蜍的染色体组型初步研究 总被引:2,自引:2,他引:0
近年来,有关两栖类的染色体组型已有不少报道。无尾两栖类中蜍蟾属(Bufo)的染色体数目分为两类:2n=22和2n=20(Blain,1972)。我们对采自新疆4个地区的绿蟾蜍进行了染色体组型分析,发现其二倍体细胞染色体数均为44,是四倍体。现将我们的初步研究报道如下。 相似文献
2.
L. W. D. van Raamsdonk 《Plant Systematics and Evolution》1985,149(3-4):287-297
The pollen fertility and seed formation of six species of theOrnithogalum umbellatum/angustifolium complex and of seven related species were studied. Four types of pollen grains could be recognized. The pollen fertility varied greatly in this complex and is not related to the ploidy level. The seed formation ofO. umbellatum showed an adaptation to a subcontinental-Mediterranean climate, that ofO. angustifolium to an Atlantic climate. In both cases raindrops seem to be important for pollination, in view of the absence of insect pollinators. After open pollination 113 seedlings were obtained in four species. Their chromosome numbers were determined. Nearly all the cultivated seedlings were aneuploid, which points to a positive selection of euploids in nature, because aneuploid individuals are rare in the wild.Biosystematic Studies on theOrnithogalum umbellatum/angustifolium Complex III.—Previous parts of this series are Part I: Taxonomy. Proceeding Kon. Ned. Acad. Wet. series C,85 (4), 563–574 (1982) andvan Raamsdonk (1984). 相似文献
3.
菘蓝多倍体育种的研究 总被引:39,自引:0,他引:39
本文报道药用植物菘蓝(Isatis indigotica Foft.)同源四倍体的诱发、鉴定、选育的研究。用0.05-0.5%浓度的秋水仙碱水溶液处理萌发的种子,或用0.05-0.3%浓度的此溶液处理幼苗的生长点,均可以获得四倍体植株。最适宜的处理时间为6-12小时。除用直接的细胞学技术鉴定多倍体植株外,一些重要的间接鉴定特征,如叶表皮保卫细胞中叶绿体数,花粉沟数可作为鉴定本种多倍体植株的可靠指标。比较了四倍体植株和二倍体亲本的生物学特性。经过数代选育,获得了性状稳定、繁殖力正常、根与叶中活性成分均有较大幅度提高、生产性能良好的品系。 相似文献
4.
鱼类远缘杂交正反交杂种胚胎发育差异的细胞遗传学分析 总被引:19,自引:0,他引:19
本文报道了鲤(Cyprinus carpio)×鲢(Hypophthalmichthys molitrix)、鲫(Carassiusauratus)×鲢、白鲫(Carassius auratus cuvieri)×鲢和鲢×鲤、鲢×鲫、鲢×白鲫的正反交试验。在鲤×鲢、鲫×鲢和白鲫×鲢3个正交组中,胚胎发育基本正常,尽管孵出的鱼苗绝大多数生命力弱,但孵化率都在50%左右;而在鲢×鲤、鲢×鲫和鲢×白鲫3个反交组中,胚胎发育均为畸形,不能孵化出苗。 胚胎发育细胞遗传学分析表明,鲤×鲢、鲫×鲢和白鲫×鲢的杂种胚胎几乎都是整倍体,而鲢×鲤、鲢×鲫×鲢×白鲫的杂种胚胎基本上是非整倍体,染色体数变化较大。这些正反交杂种胚胎发育的显著差异可能与其亲本物种间的基因组大小有关。文中还分析讨论了这些正反交差异与天然多倍体物种以及胚胎发育速度的相关性,认为天然多倍体物种可能具有一些不同于普通二倍体物种协调外源基因组的能力。 相似文献
5.
绞股蓝属的染色体研究 总被引:11,自引:2,他引:9
报道了葫芦科绞股蓝属(Gynostemma B1.)8种共20个居群的染色体数目,分别为2n=22,33,44,66,88多倍体现象极为普遍。两个亚属;绞股蓝亚属(Subgen.Gynostemma)和喙果藤亚属(Subgen.Triostellum)的染色体基数均为X=11,并结合该属植物形态特征、繁殖方式和地理分布,对普遍出现的多倍体现象进行了讨论。 相似文献
6.
Ulrich Petzoldt Kurt Bürki Gamsl R. Illmensee Karl Illmensee 《Development genes and evolution》1983,192(3-4):138-144
Summary The cleavage of fertilized mouse eggs was prevented during cytochalasin B incubation and consequently these eggs became tetraploid the following day during in vitro culture. When the eggs were cultured further in normal medium, they cleaved and gave rise to tetraploid blastocysts. Protein synthesis was analysed in these embryos at different developmental stages using two-dimensional polyacrylamide gel electrophoresis. The protein synthesis pattern of one-cell tetraploid eggs was intermediate between those of normal one- and two-cell embryos. Tetraploid two-cell embryos expressed protein sets equivalent to those of untreated four-cell embryos, and tetraploid four-cell embryos synthesized proteins similar to those of four- to eight-cell controls. At subsequent pre-implantation stages the asynchrony was no longer detectable. When fertilized eggs were cultured continuously in the presence of cytochalasin B, they became tetraploid, octoploid and more and more polyploid without cleavage occurring. The protein synthesis patterns expressed by these one-cell polyploid eggs did not resemble that of normal fertilized eggs, but were similar to those of cleaving control embryos and blastocysts of equivalent age and nuclear division. These results strongly suggest that in early mouse embryos stage-specific translation is temporally correlated with chromosome replication (karyokinesis) and independent of cell division (cytokinesis) or cell interaction.Some of these results were presented at the IX Congress of the International Society of Developmental Biologists in Basle, Switzerland, August 28–September 1, 1981 相似文献
7.
Evolutionary patterns in the antR-Cor gene in the dwarf dogwood complex (Cornus, Cornaceae) 总被引:1,自引:0,他引:1
The evolutionary pattern of the myc-like anthocyanin regulatory gene antR-Cor was examined in the dwarf dogwood species complex (Cornus Subgenus Arctocrania) that contains two diploid species (C. canadensis and C. suecica), their putative hybrids with intermediate phenotypes, and a tetraploid derivative (C. unalaschkensis). Full-length sequences of this gene (∼4 kb) were sequenced and characterized for 47 dwarf dogwood samples representing all
taxa categories from 43 sites in the Pacific Northwest. Analysis of nucleotide diversity indicated departures from neutral
evolution, due most likely to local population structure. Neighbor-joining and haplotype network analyses show that sequences
from the tetraploid and diploid intermediates are much more strongly diverged from C. suecica than from C. canadensis, and that the intermediate phenotypes may represent an ancestral group to C. canadensis rather than interspecific hybrids. Seven amino acid mutations that are potentially linked to myc-like anthocyanin regulatory
gene function correlate with petal colors differences that characterize the divergence between two diploid species and the
tetraploid species in this complex. The evidence provides a working hypothesis for testing the role of the gene in speciation
and its link to the petal coloration. Sequencing and analysis of additional nuclear genes will be necessary to resolve questions
about the evolution of the dwarf dogwood complex. 相似文献
8.
L. Qu J. F. Hancock 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,103(1):136-143
It has been suggested that ratios of coupling- to repulsion-phase linked markers can be used to distinguish between allopolyploids
and autopolyploids, because repulsion-phase linkages are much more difficult to detect in autopolyploids with polysomic inheritance
than allopolyploids with disomic inheritance. In this report, we analyze the segregation pattern of repulsion-phase linked
markers in polyploids without complete preferential pairing. The observed repulsion-phase recombination fraction (R) in such
polyploids is composed of a fraction due to crossing-over (Rc) and another fraction due to independent assortment (Ri). Ri is the minimum distance that can be detected between repulsion-phase linked markers. Because Ri is high in autopolyploids (0.3373, 0.4000, 0.4286 and 0.4444) for autopolyploids of 2n=4x, 6x, 8x and 10x), large population sizes are required to reliably detect repulsion linkages. In addition, the default linkage used in mapping-programs
must be greater than the corresponding Ri to determine whether a polyploid is a true autopolyploid. Unfortunately, much lower default linkages than the Ris have been used in recent polyploid studies to determine polyploid type, and markers have been incorporated into polyploid
maps based on the R values. Herein, we describe how mapping repulsion linkages can result in spurious results, and present
methods to accurately detect the degree of preferential pairing in polyploids using repulsion linkage analysis.
Received: 29 February 2000 / Accepted: 17 July 2000 相似文献
9.
中国葱属单生组4种植物的核型研究 总被引:1,自引:0,他引:1
对葱属单生组Allium sect.Haplostemon Boiss.的4种8个地方居群的核型进行了研究,其中3个种的核型属首次报道。研究结果表明:除在棱叶韭内同时具二倍体、三倍体和四倍体居群外,所研究的其余种的居群均为二倍体。以本研究为基础,结合国内外对该组已有的细胞学研究,得出以下结论:(1)单生组的染色体基数为8,在组内存在1A和2A两种核型类型;(2)组内随体染体类型丰富,在该组物种的生存适应方面可能起重要作用;(3)有些种(如薤白A.macrostemohn,棱叶韭A.caeruleum等)表明出现明显的种内核型分化,有的种甚至在外部形态上也有分化;(4)高度不育的三倍体(棱杏韭)和和五倍体(薤白)居群靠小鳞茎和珠芽进行无性繁殖,以此保持群的稳定和扩大。另外,从生境、繁育制度、多倍化以及这三者之间的关系等方面分析,认为 在单生组中不同的生境有利于诱发染色体的结构作数目变异。多倍化和兼性无融合生殖繁殖制度并存,则有利于克服染色色体变异所带来的育性降低这一繁育障碍,同时使居群中所发生的染色体变异得以保存,因此,多倍化和普性无融合生殖繁育制度并存是该组中多倍体类群进化的重要机制之一。 相似文献
10.
Diplazium with simply pinnate or bipinnatifid leaves. Diplazium wichurae var. wichurae, D. wichurae var. amabile, D. okudairae, and D. pin-faense are sexual diploids (2n=82; n=41II); D.× kidoi and D. × okudairaeoides are sterile diploids (2n= 82; meiosis irregular); D. donianum var. donianum is an apomictic triploid (2n=123; n=123II); D. donianum var. aphanoneuron is a sterile triploid (2n=123; meiosis irregular); D. crassiusculum, D. cavalerianum, D. incomptum, D. longicarpum, and D. pullingeri are sexual tetraploids (2n= 164; n=82II); and D. lobatum is an apomictic tetraploid (2n=164; n=164II). This is the first report of the chromosome numbers of D. lobatum, D. crassiusculum, D. incomptum, D. longicarpum, D. pullingeri, and D. × okudairaeoides, as well as the mitotic chromosome numbers of D. wichurae var. amabile, D. okudairae, D. pinfaense, and D. ×kidoi. The mitotic chromosome number, meiotic behavior, sterility, and allozyme analysis confirm that D. × kidoi and D. × okudairaeoides are hybrids between D. pin-faense and D. wichurae var. wichurae and D. okudairae and D. wichurae var. wichurae, respectively. Diplazium with simply pinnate to bipinnatifid leaves displayed an extraordinary cytological and reproductive complexity: a polyploidal
series with diploids to hexaploids, sexual and apomictic reproduction, and natural hybridization.
Received 14 August 2001/ Accepted in revised form 1 October 2001 相似文献