Karyotypic changes associated to the dispersive potential on Pomacentridae (Pisces, Perciformes)

When comparing karyotypic diversification between freshwater and marine fish, a notable increase in modifications associated to the former environment can be noticed in relation to the latter one. This fact is related to the great number of physical partitions (barriers) that exist in continental waters. Furthermore, in the marine environment, the barriers to the gene flow are complex and not always identifiable, especially when considering the participation of dynamic factors such as currents and winds associated to the dispersive potentialities of a living group. Within Perciformes fish, the Pomacentridae family stands out from the others for its intimate relation with the coral reefs, as well as for its diversity of forms and biological characteristics, providing an adequate model for studying the influence of the pelagic period of the larval stage upon the karyotypic evolution. In the present work, cytogenetic analyses were carried out on three Pomacentridae species, typical representatives of the coral reefs, Abudefduf saxatilis (2n=48, FN=52, 2 m+2sm+44a), Microspathodon chrysurus (2n=48, FN=64, 6 m+10st+32a) and Amphiprion frenatus (2n=48, FN=92, 14 m+22sm+8st+4a) that have different pelagic larval periods. The analyses between subfamilies showed a trend that the lower the dispersive potential, the greater the quantity of fixed pericentric inversions based on the basal karyotype of the Perciformes.     

Cytogenetic analysis and description of the sexual chromosome determination system ZZ/ZW of species of the fish genus Serrapinnus (Characidae, Cheirodontinae)

Four populations of Serrapinnus notomelas and one population of Serrapinnus sp.1, both belonging to the subfamily Cheirodontinae, were analyzed by Giemsa and silver nitrate impregnation techniques. We found 2n = 52 chromosomes for all populations, with interspecific differences in the karyotype formula; S. notomelas showed 16 m + 22 sm + 10 st + 4a, with fundamental number (FN) = 100 for males, and 16 m + 23 sm + 10 st + 3a, with FN = 101 for females. Serrapinnus sp.1 had 8m + 16 sm + 4 st + 24 a, with FN = 80 for males, and 8m + 15 sm + 4 st + 25 a, with FN = 79 for females. The difference in FN for the two sexes is due to a pair of heteromorphic chromosomes in the females of both species, which characterizes a ZZ/ZW-type mechanism of chromosome sexual determination. Interspecies differences were also found in nucleolus organizer regions (NORs). A simple NOR system was detected in three of four S. notomelas populations, while Serrapinnus sp.1 had two chromosome pairs with NOR. Although S. notomelas and Serrapinnus sp.1 have the same diploid number, differences in the karyotype structure indicate that these are different species. Apparently there was pericentric inversion during the karyotype evolution of these species.     

Karyotypic variability in Iheringichthys labrosus (Teleostei, Pimelodidae) from the Tibagi River basin (Paraná State, Brazil)

Cytogenetic analyses were carried out in a populational sample of Iheringichthys labrosus from the Guaraúna River (Upper Tibagi River; Paraná State, Brazil) in order to provide a karyotypic comparison with another previously studied population from the Lower Tibagi River, characterized by the presence of 32m + 8sm + 6st + 10a (2n = 56, FN = 102) and occurrence of supernumerary chromosomes (80% of individuals). The 17 specimens of I. labrosus (6 females, 10 males and 1 of unknown sex) from the Upper Tibagi River showed 2n = 56 chromosomes, a karyotype formula of 14m + 32sm + 4st + 6a (FN = 106), without evidence of sex chromosome heteromorphism or supernumerary chromosomes. The heterochromatin was detected at telomeric and centromeric positions in several chromosomal pairs. The Ag-nucleolar organizer regions were heteromorphic and located at terminal position on short arms of the 16th chromosomal pair, suggesting a positive association with heterochromatic regions. The inter-populational karyotypic differentiation reported indicates distinct evolutionary pathways within I. labrosus in the Tibagi River basin.     

Occurrence of multiple sexual chromosomes (XX/XY1Y2 and Z1Z1Z2Z2/Z1Z2W1W2) in catfishes of the genus Ancistrus (Siluriformes: Loricariidae) from the Amazon basin

Loricariid catfishes show a predominance of homomorphism in sex chromosomes, but cases of simple and multiple systems were also found. Here we describe two cases of multiple sex chromosome systems in loricariids from Brazilian Amazonia. Males of Ancistrus sp.1 "Balbina" have a modal number of 2n = 39 chromosomes, fundamental number (FN) of 78, and karyotypic formula of 27 m + 10 sm + 2 st; females have 2n = 38 chromosomes, FN = 76, and 26 m + 10 sm + 2 st. Ancistrus sp.2 "Barcelos" has 2n = 52 chromosomes for both sexes, FN = 80 for males and FN = 79 for females. Karyotypic formula is 12 m + 12 sm + 4 st + 24a for males and 11 m + 12 sm + 4st + 25a for females. The two species show different arrangements of constitutive heterochromatin blocks, which are coincident with NORs and absent in sex chromosomes. We suggest a XX/XY(1)Y(2) mechanism for Ancistrus sp.1 "Balbina", and a Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) mechanism for Ancistrus sp.2 "Barcelos". The XX/XY(1)Y(2) mechanism here reported is the second known occurrence of this type of multiple sex chromosomes for Loricariidae and the third for Neotropical fishes; the mechanism Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) represents the first record among fishes. The presence of different sex chromosome systems in Ancistrus indicates a probable independent origin and suggests that the differentiation of sex chromosomes is evolutionarily recent among species in this genus.     

Karyotypic diversity and evolution of seven mahseer species (Cyprinidae) from India

Mahseer is a group of fish species that are well known as food and game fishes. The taxonomy of the mahseer species is confusing owing to the morphological variations and habitat adaptation. Detailed karyomorphological investigations have been carried out in seven species of mahseer, using karyotyping, Ag-NOR and fluorescent staining techniques. The basic diploid chromosome number (2n), in all mahseer species, was observed to be 100; however, the karyotype formula varied among the species, which were recorded as: 20m + 14sm + 22st + 44t (fundamental arm number, FN = 134) in Tor khudree ; 22m + 24sm + 24st + 30t (FN = 146) in Tor mussullah; 12m + 22sm + 14st + 52t (FN = 134) in Tor putitora ; 20m + 24sm + 24st + 32t (FN = 144) in Tor tor ; 20m + 30sm + 24st + 26t (FN = 150) in Tor chelynoides; 20m + 20sm + 20st + 40t (FN = 140) in Tor progeneius; and 20m + 18sm + 14st + 48t (FN = 138) in Neolissochilus hexagonolepis . Silver staining of the chromosomes revealed the presence of multiple nucleolar organizer regions (NOR) in these mahseer species. The highest number of NORs was observed in T. tor (four pairs of chromosomes), whereas the other six species possessed Ag-NOR signals on only two pairs of chromosomes. Although chromomycin A₃ (CMA₃) staining induced bright fluorescence signals on same Ag-NORs sites, with CMA₃, one additional signal was observed on the p arm of subtelocentric chromosomes in T. tor , T. chelynoides , T. progeneius and N. hexagonolepis , which may indicate the presence of inactive NOR in these species. The information on cytogenetic profile of these mahseer species is discussed in the light of cytotaxonomic implications and understanding the karyoevolution of these fish species.     

Study on Karyotypes of Six Species in Angelica from Sichuan,China

Karyotypes of 6 species in Angelica L . from Sichuan are studied at population level and the karyotype of A. pseudoselinum is firstly reported . It is found that the number of chromosomes are invariably 2n = 2x =22 , with most of them are median and submedian centromeric chromosomes, while subterminal centromeric chromosomes exist in A. omeiensis . The majority of karyotypes belong to 2A, and Shihuiyao population of A. laxifoliata has 1A types . As for karyotypic formula , A. omeiensis is 2n =22 = 10m+ 2sm+ 10st , A. maowenensis is 2n =22= 16m+ 4sm+ 2sm (SAT) , A. sinensis is 2n = 22 = 14m+ 8sm, A. apaensis is 2n = 22 = 14m+8sm, and A. pseudoselinum is 2n =22 = 12m+ 8sm+2sm (SAT ) . However, different populations of A. laxiforliata don’t have the same karyotypic formulae, and there are some variations between the caryotypes more or less . According to Stebbins, A. omeiensis’s evolution status was showed by the highest index of asymmetry among six species studied in this paper , while A. laxiforliata is a little primitive because of its lower index of asymmetry and its 1A caryotypes . However , the morphological, anatomic , karyotypic characters and that of pollen grains are evolving asynchronously , suggesting that, Sichuan as one of the frequency centers of Angelica L . in China , is also one of thedifferentiation centers of Angelica L .     

Cytological studies on six cyprinid fishes

The chromosome complements of six cyprinid fishes were studied, using the routine air-drying Giemsa staining technique. The diploid chromosome number recorded is 2n = 50 (8m+18sm+14st+10t) with NF = 90 in Aspidoparia morar, 2n = 50 (8m+12sm+12st+18t) with NF = 82 in Crossocheilus latius latius, 2n = 50 (6m+12sm–16st+16t) with NF = 90 in Labeo pangusia, 2n = 70 (16m+6sm+16st–32t) with NF = 108 in Perilampus atpar, 2n = 48 (4m+6st+38t) with NF = 58 in Puntius chrysopterus and 2n = 50 (2m+2sm+4st+42t) with NF = 58 in P. tetrarupagus. Sex chromosomes are not identifiable in any of these species. A pair of marker chromosomes has been observed in all species excepting A. morar.     

Karyotype Variation and Evolution of Sect. Thea in Guizhou

Karyotypes of seven species, one variety and 11 forms of Sect. Thea occurring in Guizhou Province, were investigated by the wall degradation hypotonic method. The micrographs of their somatic metaphase are shown in plates 1-2 and the parameters of chromosomes according to Li and Chen (1985) are given in Table 1 and the idiograms in Fig. 1. The karyotype formulae are as follows: Camellia quinquelocularis 22=30=24m+6sm; C. tetracocca 2n=30=22m+8sm; C. taliensis 2n=30=22m+8sm; C. gymnogyna 2n=30=22m +6sm+2st and 2n=30=20m=8sm+2st; C. gymnogynoides 2n=30=22m +6sm+2st and 2n=30=20m+8sm+2st; C. jungkiangensis 2n=30=20m+8sm+2st; C. sinensis 2n =30+20m+8sm+2st, and C. sinensis var. ruoella 2n=30=20m+8sm+2st. All the karyotypes belong to Stebbins “2A”. The following main aspects are discussed. 1. Chromosome numbers: All these species are found to have 2n=30. Based on the previous and present reports, It clearly indicates that evolution of this group has taken place mainly on diploid level, but not on polyploid one. 2. The karyotype variation: Generally, all the karyotypes examined are similar, but according to symmetry of karyotype, they may be grouped into two types. One is characterized by metacentric (m)and submetacentric (sm)chromosomes, involving C. quinquelochlaris, C. tetracocca, C. taliensis, while the other is characterized by a pair of subtelocentric (st) chromosome besides m and sm chromosomes, involving C. gymnogyna, C. gymnogynoides, C. jungkiangensis, C. sinensis and C. sinensis var. ruoella. It is suggested that the mechanism for karyotype variation and speciation in Sect. Thea be pericentric inversion or reciprocal translocation. The first type is more symmetrical than the second one, and is thus relatively primitive. 3. The orginal center of Sect. Thea: Based on the analysis of karyotypes, morphological characters, geographical distribution and biochemical features, the authors consider that the Yunnan-Guizhou plateau including the contiguous area in Yunnan, Guangxi and Guizhou is the original center, from where it radiated, resulting in the present distribution pattern of Sect. Thea.4. Taxonomic treatment of Sect. Thea: The taxonomic treatment of Sect. Thea is complicated and still confused up to now. The number of species is more than 40 according to Zhang’s taxonomic system (1984), but, recently, most of them are reduced by Min (1992). Further work should be based on the concept of morphological discontinuity and in formation from other branches of sciences. Whether two types of karyotype are two biological species remains questionable.     

浙江鸭跖草属植物的核型研究

本文报道了浙江二种鸭跖草属植物──饭包草ＣｏｍｍｅｌｉｎａｂｅｎｇａｌｅｎｓｉｓＬ．和鸭跖草ＣｏｍｍｅｌｉｎａｃｏｍｍｕｎｉｓＬ．的染色体数目与核型：ＣｏｍｍｅｌｉｎａｂｅｎｇａｌｅｎｓｉｓＬ．核型为Ｋ（２ｎ）＝２２＝１８ｍ＋４ｓｍＣｏｍｍｅｌｉｎａｃｏｍｍｕｎｉｓＬ．核型为Ｋ（２ｎ）＝２２＝４Ｍ＋１２ｍ＋４ｓｍ＋２ｓｔ     

A Chromosomal Study on 7 Species of Smilax L.

The chromosome numbers and karyotypes of 7 species of Smilax L. in Liliaceae (s. 1.) are cytotaxonomically studied in this work. Their karyotypic characters, distinction between the species and the chromosomal basis of sexual differentiation are discussed. The karyotypes of most species are first reported. The results are shown as follows (see Tables 1-4 for the chromosome parameters and the karyotype constitution; Fig. 1 for their idiograms): 1. Smilax nipponica Miq. The species is one of the herbaceous species distributed in East Asia. Two karyotypes, 2n = 26(type A) and 2n = 32 (type B), are found in the species (Plate 1: 1-7). The karyotype of No. 88032 (uncertain of -L--M--S- sexuality) is 2n = 26 = 2m + 6st + 6m + 4sm + 6sm + 2st. The karyotype has 4 pairs of L chromosomes, of which the first three pairs are subterminal, and the 4th is median. The karyotype belongs to 3B. No. 88045 (the male) and No. 88046 (the female) have 2n = 32. Their karyotypes are basically uniform, and both are -L--M-- S 2n=32= 2m+4sm+ 2st+ 2m+4sm+ 6m+ 10sm + 2st, also with 4 pairs of L chromosomes, but the 2nd pair is median, and thus different from the type A. The karyotype belongs to 3B. The first pair of chromosomes of the male are distinctly unequal in length, with the D. V. (0.93) of relative length between them obviously greater than that of the female (0.1). The pair seems to be of sex-chromosomes. Sixteen bivalents (n= 16) were observed at PMCs MI of No. 88045 (Plate 1: 4). The major difference between the karyotypes A and B are greater relative length of L chromosomes in the type A than in the type B, and the increase of chromosome number in the karyotype B mainly due to the increase of st chromosomes. Nakajima (1937)reports 2n= 30 for S. hederacea var. nipponica (=S. nipponica, Wang and Tang, 1980). 2. S. riparia A. DC. This species is also herbaceous, distributed in East Asia. Thirty chromosomes were found in root-tip cells (uncertain of sexuality). The kar -L--M--S-yotype is 2n = 30 = 8st + 6sm + 2st + 6m + 6sm + 2st (Plate 3: 1, 5), consisting mainly of sm and st chromosomes. There are 4 pairs of L chromosomes which are all subterminal and the m chromosomes appear to fall all into S category. Though the karyotype belongs to 3B, it is less symmetrical than that of S. nipponica. The species is karyologically rather different from S. nipponica, therefore. The first pair of chromosomes of this material are unequal in length, and it may be a male. The karyotype of this species is first reported. 3. S. sieboldii Miq. The species is a thorny climbing shrub, distributed in East Asia. At PMCs All, 16 chromosomes (n= 16) were found (Plate 2: 6), in accordance with Nakajima's (1933) report for a Japanese material. 4. S. china L. This species, a thorny climbing shrub, is of a wide distribution range mainly in East Asia and Southeast Asia. Two karyotypes were observed in different populations. (1) The population from Xikou has 2n = 96(6x) = 20st+L- -M- 6t + 6sm + 12st + 52(S) (Plate 3:7), of which the first three pairs of chromosomes are terminal, different from those in the other species. The arm ratios of both L and M chromosomes are larger than 2.0, which resembles those of S. davidiana. (2) PMCs MI of the population from Shangyu shew 15 chromosomes (n 15). The hexaploid of the species is recorded for the first time. Hsu (1967,1971) reported 2n = 30 from Taiwai and Nakajima (1937) recorded n = 30 from Japan, which indicates that the karyotype of the species varies not only in ploidy, but also in number. 5. S. davidiana A. DC. The somatic cells were found to have 32 chromosomes, and PMCs MI shew 16 bivalents (Plate 2: 1-5). The karyotype is 2n = 32=-L- -M- -S 8st + 4sm + 4st + 8sm + 8st. The karyotype belongs to 3B, and is less symmetrical than those in herbaceous species. The D. V. (0.20) of relative length between the two homologues of the first pair is slightly larger in the male than in the female (0.14), and it is thus difficult to determine whether they are sexual chromosomes or not. 6. S. glabra Roxb. The species is a non-thorny climbing shrub, distributed in East Asia and Southeast Asia. 32 chromosomes were found in somatic cells. The -L- -M- - Skaryotype is 2n= 32= 8st + 10st+6sm+8st (Plate 3: 2, 6),with only 3 pairs of sm chromosomes (12, 13 and 16th). The karyotype is more asymmetric than that of S. davidiana, although it is also of 3B (Table 1). The karyotype is first reported for the species. 7. S. nervo-marginata Hay. var. liukiuensis (Hay.) Wang et Tang The variety has a relatively narrow distribution range, mainly occurring in eastern China. The chromosomal number of somatic cells is 2n= 32 (Plate 3: 3-4). The karyotype is -L- -M- -S 2n = 32 = 2sm + 6st + 2sm + 2st + 2m + 6sm + 12st, evidently different from that of S. glabra. The first pair of chromosomes are submedian, and much longer than the 2nd to 4th pairs. The ratio in length of the largest chromosome to the smallest one is 4.3. The symmetric degree is of 3C, a unique type. The karyotype of the species is reported for the first time. In Smilax, the known basic numbers are 13, 15, 16 and 17. The two herbaceous species distributed in East Asia have three basic numbers: 13, 15 and 16, while the woody species studied mainly have 16, with no 13 recorded. Mangaly (1968) studied 8 herbaceous species in North America and reported 2n=26 for them except S. pseudo-china with 2n=30. Mangaly considered that a probably ancestral home of Smilax, both the herbaceous and woody, is in Southeast Asia and the eastern Himalayas, and speculated that the ancestral type of Sect. Coprosmanthus is possibly an Asian species, S. riparia. The karyotypes of the two herbaceous species in East Asia consist mostly of sm and m chromosomes, whereas those for the North American species are all of st chromosomes. Based on the general rule of karyotypic evolution, i.e. from symmetry to asymmetry, his speculation seems reasonable. Researches on sex-chromosomes of Smilax have been carried out since 1930 (Lindsay, 1930; Jensen, 1937; Nakajima, 1937; Mangaly, 1968), and they are generally considered to be the largest pair, but there is still no adequate evidence. The result of our observation on S. nipponica may confirm that the first pair of chromosomes of this species is XY type of sex-chromosomes. Chromosomes of the genus are small and medium-sized, varying between 1-6 μm, slightly larger in herbaceous species than in woody ones, larger in the karyotype of 2n=26 than in that of 2n=32. Based on karyotype constitution of the above 5 species, the karyotype in the genus is characterized by 4 pairs of L chromosomes and 2-5 pairs of M chromosomes, and mostly st and sm chromosomes, and by rather asymmetrical 3B type. The degree of symmetry in the above 5 species is from Sect. Coprosmanthus to Sect. Coilanthus, and herbaceous species towoody ones.     

黄精属细胞分类学研究Ⅱ.四川金佛山地区黄精属植物核型

本文对四川金佛山地区4种黄精属植物的核型进行了研究,其结果为:滇黄精:2n=26=6m+12sm(2SAT)+8st(2SAT);距药黄精:2n=26=10m+4sm+12st;垂叶黄精:2n=30=14m(2SAT)+4sm+10st+2t、2n=28=14m+6sm+6st+2t;湖北黄精:2n=30=12m+8sm+10st、2n=28=6m+10sm+10st+2t、2n=22=2m+12sm 8st。通过与其它地区黄精属植物染色体数目与形态的比较,发现本地区所有种类的染色体数目普遍偏高,无论在染色体基数或染色体形态上都比较接近喜马拉雅山地区分布的种类。从实验结果进一步看出了黄精属的染色体变异是相当明显的,并主要表现为非整倍性变异;在有些情况下,染色体数目与结构的变异能与某些形态学特征相联系。     

10种菊属(Dendranthema)植物的细胞学研究

对菊属(Dendranthema)在中国分布的10种20个居群的材料进行了细胞学研究,首次报道了异色菊(2n＝18,36)、银背菊(2n＝56)、楔叶菊(2n＝18,72)的染色体数目和核型,以及蒙菊(2n＝18)的染色体数目新纪录,并结合前人的工作,分析了菊属的核型特征和演化趋势,及其与该属分类群的关系。     

角堇与大花三色堇染色体核型分析

以2份角堇与4份大花三色堇自交系为试验材料,采用染色体常规压片方法,观察和分析了它们的细胞染色体数目、相对长度、平均臂比等核型指标,以明确两种植物细胞学特点,为分类以及育种提供理论依据。结果表明:(1)2份角堇自交系染色体数目均为2n=2x=26,染色体基数为x=13,染色体核型公式分别为2n=2x=26=8m+12sm+6st、2n=2x=26=4m+16sm+6st,核型不对称系数为67.20%~70.10%,核型分类均属于3B。(2)4份大花三色堇自交系均为四倍体,其中2份(EYO-1-2-1-4、DSRFY-1-1-2)染色体数目为44,核型公式为2n=4x=44=4m+16sm+6st、2n=4x=44=16m+24sm+4st;2份(G10-1-3-1-4、XXL-YB-1-1-1-1)染色体数目为48,核型公式分别为2n=4x=48=8m+20sm+20st、2n=4x=48=4m+36sm+8st,核型不对称系数为66.74%~71.77%,核型分类属于2B、3B。     

我国11种披碱草的核型研究

本文报道了中国产的11种披碱草属植物的核型,其中9种为首次报道。结果如下:老芒麦2n=4x=28=24m+4sm(2SAT);披碱草2n=6x=42=36m(2SAT)+6sm(4SAT);青紫披碱草2n=6x=42=32m+10sm(4SAT);垂穗披碱草2n=6x=42=34m+8sm(2SAT);圆柱披碱草2n=6x=42=32m+10sm(2SAT);短芒披碱草2n=6x=42=30m+12sm(4SAT);黑紫披碱草2n=6x=42=36m(6SAT)_1+6sm;毛披碱草2n=6x=42=30m+12sm(6SAT);紫芒披碱草2n=6x=42=22m=12sm(2SAT)+8st(4SAT);肥披碱草2n=6x=42=34m(2SAT)+6sm(4SAT)+2st;麦(?)草2n=6x=42=30m(4SAT)+12sm(2SAT)。     

黄精属细胞分类学研究——Ⅱ.四川金佛山地区黄精属植物核型

本文对四川金佛山地区4种黄精属植物的核型进行了研究,其结果为:滇黄精:2n=26=6m+12sm(2SAT)+8st(2SAT);距药黄精:2n=26=10m+4sm+12st;垂叶黄精:2n=30=14m(2SAT)+4sm+10st+2t、2n=28=14m+6sm+6st+2t;湖北黄精:2n=30=12m+8sm+10st、2n=28=6m+10sm+10st+2t、2n=22=2m+12sm 8st。通过与其它地区黄精属植物染色体数目与形态的比较,发现本地区所有种类的染色体数目普遍偏高,无论在染色体基数或染色体形态上都比较接近喜马拉雅山地区分布的种类。从实验结果进一步看出了黄精属的染色体变异是相当明显的,并主要表现为非整倍性变异;在有些情况下,染色体数目与结构的变异能与某些形态学特征相联系。     

赖草属5个种的核型与进化

报道了国产赖草属５个种的核型,即大赖草,２ｎ＝４ｘ＝２８＝２４ｍ（２ＳＡＴ）＋４ｓｍ（２ＳＡＴ）;粗穗赖草２ｎ＝４ｘ＝２８＝２２ｍ（２ＳＡＴ）＋４ｓｍ＋２ｓｔ（２ＳＡＴ）;若羌赖草,２ｎ＝４ｘ＝２８＝２０ｍ（４ＳＡＴ）＋６ｓｍ＋２ｓｔ（２ＳＡＴ）;羊草,２ｎ＝４ｘ＝２８＝２２ｍ（４ＳＡＴ）＋２ｓｍ＋４ｓｔ（４ＳＡＴ）;窄颖赖草,２ｎ＝４ｘ＝２８＝２２ｍ（２ＳＡＴ）＋４ｓｍ（２ＳＡＴ）＋２ｓｔ（２Ｓ     

A Study on Karyotypes of 6 Species of Elymus in China

The present paper deals with the karyotype analysis of 6 species of Elymus which are native to Qinghai-Tibetan plateau. The number of somatic chromosomes in roottip cells of the 6 species and their karyotypes are reportad here for the first time, and they are all hexaploid, with 2n=6x=42. The karyotype formulae are as follows: E. melantherus, 2n=6x=42=32m+10sm, E. kengii, 2n=6x=42=34m+8sm, E grandiglumis, 2n=6x=42= 30 m+12 sm, E. laxiflorus, 2n=6x=42=32 m +10 sm, E. kokonoricus, 2n+6x=42=34 m +8 sm, E. longiglumis, 2n+6x=42=34 m+8 sm. No satellites have been founded in the 6 species and all the karyotypes belong to 1B or 2B type:     

仲彬草属5种植物的核型研究

本文对我国西部高原仲彬草属Ｋｅｎｇｙｉｌｉａ５种植物的核型进行了分析。它们的染色体数目均为２ｎ＝４２,六倍体。核型是：糙毛鹅观草Ｋ．ｈｉｒｓｕｔａ,２ｎ＝６ｘ＝４２＝３６６＋６ｓｍ;青海鹅观草Ｋ．ｋｏｋｏｎｏｒｉｃａ,２ｎ＝６ｘ＝４２＝３６ｍ＋６ｓｍ：黑药鹅观草Ｋ．ｍｅｌａｎｔｈｅｒａ,２ｎ＝６ｘ＝４２＝３８ｍ＋４ｓｍ;硬秆鹅观草Ｋ．ｒｉｇｉｄｕｌａ,２ｎ＝６ｘ＝４２＝３８ｍ＋４ｓｍ;窄颖鹅观草Ｋ．ｓｔｅｎａｃｈｙｒａ,２ｎ＝６ｘ＝４２＝３８ｍ＋４ｓｍ。它们的核型属于１Ｂ或２Ｂ型。染色体中均未发现随体。     

四川当归属六种植物的核型

从居群水平对四川当归属(AngelicaL.)6种植物的核型进行了研究,其中管鞘当归核型为首次报道。6个种的染色体均为2n=2x=22,多为中部和近中部着丝粒染色体,核型多为2A型,仅疏叶当归石灰窑居群为1A型;峨眉当归核型为2n=22=10m 2sm 10st,茂汶当归核型为2n=22=16m 4sm 2sm(SAT),当归核型为2n=22=14m 8sm,阿坝当归核型为2n=22=14m 8sm,管鞘当归核型为2n=22=12m 8sm 2sm(SAT),而疏叶当归不同居群的核型或多或少发生了不同程度的变异。参照Stebbins的观点,峨眉当归以核型不对称系数最高而在6个种中显示一定的核型进化性,疏叶当归不对称系数较低,且出现1A型核型因而体现出一定的原始性。但是,综合形态解剖、花粉性状以及核型特征可以看出,四川当归属植物各性状间具有进化的不同步性,这也表明,作为当归属分布频度中心之一的四川地区,同时也是当归属的分化中心之一。