风毛菊属5种植物的核型分析

采用常规压片法,对风毛菊属(Saussurea)5种植物的染色体数目和核型类型进行分析。结果表明:大耳叶风毛菊(S.macrota)核型公式为2n=2x=26=10m+12sm+4st,属2A型;长梗风毛菊(S.dolichopoda)核型公式为2n=2x=26=14m+8sm+4st,属2A型;川陕风毛菊(S.licentiana)核型公式为2n=2x=28=12m+16sm,属2B型;杨叶风毛菊(S.populifolia)核型公式为2n=2x=28=6m+18sm+4st,属2B型;尾叶风毛菊(S.caudata)核型公式为2n=2x=30=14m+14sm+2st,属2A型。这5种风毛菊属植物中,除大耳叶风毛菊染色体数目和核型类型与前人报道的一致外,其余4种植物的染色体数目和核型类型均为首次报道,并在川陕风毛菊中发现1对B染色体。     

二倍体石蒜在安徽发现

本文以根尖细胞为材料,观察了石蒜Lycoris radiata(L′Her．)Herb．三个不同居群植物的染色体数目和核型,发现石蒜为一复合体,包括两种不同类型：(1)三倍体类型,主要包括一群以鳞茎无性繁殖的园艺栽培植株,其染色体数目和核型为2n＝33=33t(st),属“4A”核型,且极其稳定。(2)二倍体类型,主要包括一群野生植株,变异较大,我们发现有下列几种情况：一是芜湖产石蒜(L．radiata)的野生材料,其染色体数目和核型为2n=21+1B=1m+12st+8t+1B,属“3A”核型,在石蒜种内迄今未见有类似报道;另一是黄山产野生材料,观察到两个细胞型,绝大多数细胞为2n=22＝12st+1Ot,极个别细胞出现2n＝22+1B=6st+14t+2T+1B的情况,均属“4A”核型。芜湖和黄山野生材料的染色体数目和核型均为首次报道。石蒜(L．radiata)的二倍体类群也是首次在安徽发现。     

加拿大一枝黄花入侵的细胞学机制

对入侵植物加拿大一枝黄花(Solidago canadensis L.)和同属土著种一枝黄花(Solidago decurrens Lour.)的染色体计数,并对核型进行了分析.实验结果:加拿大一枝黄花染色体数目为2n=54,核型公式为k(2n)=6x=54＝46m 8sm(0-6SAT),核型类型为2A型;一枝黄花染色体数目为2n=18,核型公式为k(2n)=2x=18=16m 2sm(0-2SAT),核型类型为1A型.通过对一枝黄花属(Solidago L.)植物染色体数目的统计分析,判断该属的染色体基数为9.通过对多倍体基因表达导致植物适应进化的讨论得出:多倍体是入侵植物特征,可能是植物入侵的内在机制.     

浙江产7种菝葜的染色体研究

本文报道浙江产菝葜属smilax 7个种的染色体数目和核型。S．nipponica有两种核型,2n＝26和2n=32,均为3B型,但后一种细胞型的雄株的第一对染色体大小不等,可能为性染色体;S.riparia 2n=30,属3B型;S．siebodii n＝16;S. china有两个染色体数目,2n＝96 和n＝15;S. davidiana 2n=32,属3B型,对减数分裂MI的观察发现n＝16;S．glabra 2n=32,亦属3B型：S. nervo-marginata var．liukiuensis 2n=32,属3C型。讨论了种间在核型上的差异、属的基数、核型演化趋势和性染色体等问题。     

云南大叶茶细胞学研究

本文采用去壁低渗法研究了云南大叶茶的染色体核型,间期核形态和多核现象。结果表明大多数染色体是中部着丝粒染色体,5对是近中部着丝粒染色体,第7和12对染色体中各有1条具随体染色体。根据Levan等的分类原则,其核型为2n=20m+8sm+2sm(SAT),属于Stebbins核型分类的“2A”型,同时亦发现有“2B”型的核型。云南大叶茶间期核型为浓密分散型和复杂染色中央微粒型两种;并首次发现茶树中的多核现象,在所观察的1250个细胞中有6个是具双核细胞(占0.48％),有2个是具三核细胞占(0.16％)。另外,本文还对部份山茶属植物的核型进行了讨论。从核型上可以看出:(1)山茶属植物在进化上属于较原始的种系;(2)山茶属植物核型的进化基本符合Stebbins提出的植物界核型进化的规律,即对称—→不对称;(3)山茶属植物的核型在一定范围内变异甚大,这种变异没有一定的规律性。这些观点与张宏达提出的山茶属植物的分类系统基本吻合。带随体的染色体数目在山茶属植物核型的进化上没有什么明显的变化规律。     

濒危植物三棱栎四个居群的核型

报道了濒危植物三棱栎 4个居群的染色体数目和核型 ,4个居群的核型公式均为 2n =14 =10m 2sm 2st 2bs,核型类型均为 2A。间期核为复杂染色中心型 (complexchromocentertype) ,细胞有丝分裂前期染色体为中间型 (interstitialtype)。 4个居群在前期染色体中 ,可观察到2个B染色体 ,但在中期染色体中较少发现。根据核型分析结果 ,4个居群间核型变异不明显     

山茶属植物核型研究进展

本文收集整理了目前已发表的山茶属植物的核型资料。按张宏达的分类系统,本文共收录了94种（含15变种）的核型和29种（含4变种）的染色体数目。分析表明,山茶属植物染色体基数稳定X＝15,核型多为2A或2B型,核型的进化规律符合Stebbins提出的从对称向不对称方向进化的理论。山茶属植物的核型存在杂合性和多态性。本文中作者提供15种的核型,其中2种的核型为首次报道。     

直瓣苣苔属、筒花苣苔属和吊石苣苔属4个种的核形态学研究

本文报道了苦苣苔科直瓣苣苔属Ancylostemon、筒花苣苔属Briggsiopsis和吊石苣苔属Lysionotus 中4个种的染色体数目和核形态。凹瓣苣苔A．aureus的染色体数目为n=34,与其近缘种凸瓣苣苔 A．convexus的染色体数目相同。该种的核型公式为2n=20m(1sat)+14sm,核型类型属于2A。间期核 为复杂染色中心型(complex chromocenter type);细胞有丝分裂前期的染色体为近基型(proximal type) 我国特有单种属筒花苣苔属Briggsiopsis的间期核为简单—复杂染色中心型(simple-complex chromocenter type);细胞有丝分裂前期的染色体为中间—渐变型(interstitial—gradient type);核型公式为2n=34=25m +6sm+3st,与近缘类群——粗筒苣苔属Briggsia染色体数目2n=34,68相比,无论染色体数目还是核 型均显示比较原始的特征。吊石苣苔属的蒙自吊石苣苔L．carnosus和翅茎吊石苣苔L．serratus D． Don var．pterocaulis的核型公式分别是2n=30=21m+5sm+3st+1t和2n=32=21m+10sm+1t。核 型类型分别属于2A和2B。间期核均为简单—复杂染色中心型(simple-complex chromocenter type);细胞 有丝分裂前期的染色体为渐变型(gradient type)。     

野牡丹科6种植物染色体数目及核型分析

研究了野牡丹科国产野牡丹属(Melastoma L.)4种植物和从国外引种的蒂牡花属(Tibouchina Aubl.)2种植物的染色体数目,并对4种野牡丹属植物的核型进行分析。结果表明, 野牡丹属植物的染色体数目为2n=24,为二倍体植物,蒂牡花属的蒂牡花(T. urvillean)和银毛野牡丹(T. heteromall)的染色体数目为2n=36。核型公式为：野牡丹(M. malabathricum) 2n=10m(2SAT)+14sm;毛稔(M. sanguineurn) 2n=10m+12sm+2st;地稔(M. dodecandrum) 2n=12m+12sm;细叶野牡丹(M. intermedium) 2n=12m＋10sm+2st。核型分析表明国产野牡丹属植物染色体为小染色体,绝对长度为0.43~1.79 µm;核型不对称系数为59.47~62.91,均属2B型。野牡丹属植物的核型为首次报道。     

豹子花属及百合属13种25居群的核型研究

采用常规压片法对豹子花属6种11居群和百合属7种14居群进行了核型研究,并用不对称系数AI度量核型不对称性,以CVCL-CVCI散点图比较近缘类群之间的亲缘关系。结果表明： 1）除美丽豹子花 No-mocharis basilissa 为三倍体外,其余全为二倍体 2）核型在种间、居群间存在变异,特别是在随体染色体的数目和位置以及B染色体的有无上种间存在明显差别 3） CVCL-CVCI散点图显示豹子花属与百合属关系密切 4）染色体结构变异产生数量和类型不同的次缢痕,是豹子花属植物进化的主要方式。豹子花属在从其起源地和分化中心高黎贡山向四周扩散时,细胞核型方面伴随着出现了非整倍体、三倍体、 B染色体和次缢痕进化的类型.     

加拿大引进的二倍体燕麦种质的核型鉴定

采用常规压片法对砂燕麦、西班牙燕麦和短燕麦3个二倍体燕麦种进行了核型研究。结果表明:砂燕麦染色体核型公式为2n=2x=14=10m+4sm(2SAT),具近中部和中部着丝点染色体,第4对染色体组的短臂上有1对随体,核不对称系数为68.17%;西班牙燕麦染色体核型公式为2n=2x=14=10m+4sm(2SAT),具近中部和中部着丝点染色体,第7对染色体短臂上有1对随体,核不对称系数为59.31%;短燕麦染色体核型公式为2n=2x=14=6m+4sm+4st(2SAT),具近端部、近中部和中部着丝点染色体,第6对染色体组的短臂上有1对随体,核不对称系数为63.91%。虽然3个燕麦种的核型均为2A,但它们的染色体形态有明显不同,比较认为砂燕麦相对进化,短燕麦次之,西班牙燕麦较原始。本研究对燕麦种质资源的核型分析及进化地位研究具有参考价值。     

Evolutionary rate of the mammalian karyotype

Making pairwise comparisons of karyotypes of species belonging to a genus, we have calculated the probabilities that two randomly chosen species from a genus have the same karyotype. This probability decreases exponentially with time. Thus if we know the divergence time of species from a common ancestor, we can know the rate at which a karyotype changes in unit time. According to our result, mammalian karyotypes appear to be evolving at a rate of one change of either chromosomal number or arm number in every two and half million years. Data indicate that the rate of evolution in chromosome number and arm number are fairly similar in most of mammalian genera. The genus Peromyscus is, however, an exception and exhibits a rather rapid change in the arm number due to heterochromatin changes, but a very slow evolution in the chromosome number.     

Data reassessment in a phylogenetic context gives insight into chromosome evolution in the giant genus Solanum (Solanaceae)

Chromosome data are fundamental in evolution. However, there has been no attempt to synthesize and evaluate the significance of such information from a phylogenetic perspective in the giant genus Solanum, which was the aim of this work. New and published information of the main cytotaxonomic features (chromosome number, polyploidy, total length of the haploid complement, mean chromosome length, mean arm ratio, karyotype formula, nuclear DNA amount, number/position of rDNA sites) was compiled and mapped onto an embracing Solanaceae phylogeny, performing Ancestral States Reconstruction. There were 506 Solanum species with chromosome counts (49.7% from an estimated total of 1,018 spp.), with x?=?12 being the most frequent number (97%). Species with karyotypes represent 18.8%, while 8% have been studied with any molecular cytogenetic technique. Chromosome characters showed transitions associated with supported nodes, some of which have undergone fewer transitions than others. The common ancestor of all Solanum was a diploid with 2n?=?24, a karyotype with st and/or t chromosomes, 2C DNA content of 1–1.2 pg, one locus of 18–5.8–26S rDNA and one of 5S, both loci being asyntenic. The chromosomal variables behave as homoplastic, with reversions in all branches. The analysed characters were sorted from more to less conserved: asynteny of rDNA loci; number of sites of 18–5.8–26S; chromosome number; karyotype formula; number of 5S loci. This pattern of chromosomal evolution distinguishes Solanum from closely related genera and from genera from other families with a similar number of species.     

Major cytogenetic landmarks and karyotype analysis inDaucus carota and other Apiaceae

Karyotype analysis provides insights into genome organization at the chromosome level and into chromosome evolution. Chromosomes were marked for comparative karyotype analysis using FISH localization of rDNA genes for the first time in Apioideae species including taxa of economic importance and several wild Daucus relatives. Interestingly, Daucus species did not vary in number of rDNA loci despite variation in chromosome number (2n = 18, 20, 22, and 44) and previous publications suggesting multiple loci. All had single loci for both 5S and 18S-25S (nucleolar organizing region) rDNA, located on two different chromosome pairs. The 5S rDNA was on the short arm of a metacentric chromosome pair in D. crinitus (2n = 22) and D. glochidiatus (2n = 44) and on the long arm of a metacentric pair in other Daucus species, suggesting possible rearrangement of this chromosome. For other Apiaceae, from two (Apium graveolens), to three (Orlaya grandiflora), to four (Cuminum cyminum) chromosomes had 18S-25S rDNA sites. Variability for number and position of the 5S rDNA was also observed. FISH signals enabled us to identify 20-40% of the chromosome complement among species examined. Comparative karyotype analysis provides insights into the fundamental aspects of chromosome evolution in Daucus.     

About the possibility of hybridogenesis in the species origin of the midge Chironomus usenicus Loginova et Beljanina (Chironomidae,Diptera)

Hybridogenesis as a possible way of speciation in Chironomidae was considered with special reference to the species Chironomus usenicus resulting from hybridization between C. plumosus and C. behningi. The three species had 2n = 8 and belonged to the thummi cytocomplex with chromosome arm combinations AB, CD, EF, and G. Arm G had a marker chromosome disk sequence (CDS) and was used to demonstrate the hybrid origin of C. usenicus. Most C. usenicus larvae were heterozygous in CDS of arm G. CDS use G2 proved to be identical to CDS beh G1 of C. behningi and CDS use G1, to CDS plu G1 of C. plumosus. It was assumed that C. usenicus results from hybridization between eurybiont C. plumosus and stenobiont C. behnigni at the boundary of their species areas, in freshwater or brackish water bodies of the southern Saratov oblast and northern Kazakhstan. Morphologically and karyotypically, the hybrid was probably similar to C. plumosus. Crosses with C. plumosus eliminated virtually all C. behningi chromosome sequences from the karyotype of the hybrid. Further chromosome divergence resulting in C. usenicus involved a number of chromosome rearrangements, including duplication of pericentric heterochromatin and other chromosome regions; inversion, which occurred in arm F (regions 13-16) and was fixed in the karyotype; and other paracentric inversions and deletions accumulated in heterozygote in the karyotype pool of the species. Since C. behningi was eliminated from the introgression zone and its species are reduced, the assimilation character was assumed for introgressive hybridization of C. behningi and C. plumosus.     

西藏巨柏核型的图象自动分析与识别的研究

我们应用图象自动分析和识别的原理和方法,建立了植物染色体自动分析CHROMHUK软件系统,并首次对西藏巨柏进行了核型自动分析,抽取了染色体多个特征多数:相对长度、臂比、着丝点指数、相对体密度和次缢痕相对长度.对247个巨柏体细胞进行多参数数据统计和分析,并设置95°.置信判别区域和树分类判别.实现了染色体自动配对和分类,并由计算机直接输出染色体的组型图和核型模式图.分析结果表明:巨柏体细胞的染色体数目为2n=22,按Levan的分类标准,其核型公式为2n=4m(SC)+16m+2sm.据Stabbins分类为1A型.     

野生蔬菜十里香的核型研究

十里香的染色体核型国内一直未见报道,利用根尖压片法对野菜十里香进行核型分析,统计观察了30个准确计数染色体根尖有丝分裂的中期细胞。实验结果表明：野菜十里香的染色体数为2n=22,其核型公式为2n=22=12m＋4sm＋6st。利用有丝分裂过程中的染色体核型,可明确区分马兰属植物在表现型上难以区别的类型。染色体数目、相对长度、着丝粒位置和随体有无等都可以作为马兰属植物的分类指标。     

Karyotype differentiation of four Cestrum species (Solanaceae) revealed by fluorescent chromosome banding and FISH

The karyotypes of four South American species of Cestrum (C. capsulare,C. corymbosum,C. laevigatum and C. megalophylum) were studied using conventional staining, C-CMA/DAPI chromosome banding and FISH with 45S and 5S rDNA probes. The karyotypes showed a chromosome number of 2n = 2x = 16, with metacentric chromosomes, except for the eighth submeta- to acrocentric pair. Several types of heterochromatin were detected, which varied in size, number, distribution and base composition. The C-CMA(+) bands and 45S rDNA were located predominantly in terminal regions. The C-CMA (+) /DAPI (+) bands appeared in interstitial and terminal regions, and the C-DAPI (+) bands were found in all chromosome regions. The 5S rDNA sites were observed on the long arm of pair 8 in all species except C. capsulare, where they were found in the paracentromeric region of the long arm of pair 4. The differences in band patterns among the species studied here, along with data from other nine species reported in the literature, suggest that the bands are dispersed in an equilocal and non-equilocal manner and that structural rearrangements can be responsible for internal karyotype diversification. However, it is important to point out that the structural changes involving repetitive segments did not culminate in substantial changes in the general karyotype structure concerning chromosome size and morphology.     

Tempo and mode in karyotype evolution revealed by a probabilistic model incorporating both chromosome number and morphology

Karyotype, including the chromosome and arm numbers, is a fundamental genetic characteristic of all organisms and has long been used as a species-diagnostic character. Additionally, karyotype evolution plays an important role in divergent adaptation and speciation. Centric fusion and fission change chromosome numbers, whereas the intra-chromosomal movement of the centromere, such as pericentric inversion, changes arm numbers. A probabilistic model simultaneously incorporating both chromosome and arm numbers has not been established. Here, we built a probabilistic model of karyotype evolution based on the “karyograph”, which treats karyotype evolution as a walk on the two-dimensional space representing the chromosome and arm numbers. This model enables analysis of the stationary distribution with a stable karyotype for any given parameter. After evaluating their performance using simulated data, we applied our model to two large taxonomic groups of fish, Eurypterygii and series Otophysi, to perform maximum likelihood estimation of the transition rates and reconstruct the evolutionary history of karyotypes. The two taxa significantly differed in the evolution of arm number. The inclusion of speciation and extinction rates demonstrated possibly high extinction rates in species with karyotypes other than the most typical karyotype in both groups. Finally, we made a model including polyploidization rates and applied it to a small plant group. Thus, the use of this probabilistic model can contribute to a better understanding of tempo and mode in karyotype evolution and its possible role in speciation and extinction.     

蜘蛛抱蛋属植物的核型不对称性分析

报道了蜘蛛抱蛋属(Aspidistra)两种植物的染色体数目和核型,其中河口蜘蛛抱蛋(A.hekouensi)的染色体数目(2n=38)为首次报道,四川蜘蛛抱蛋(A.sichuanensis)染色体数目也为2n=38,但其核型与以往的报道有差别.使用染色体内不对称系数(A1)和染色体间不对称系数(A2)对该属34种植物核型的不对称性进行了分析,结果表明该属植物的核型似乎并没有向不对称性增强的方向演化.