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.     

Allozyme and morphology evolution in European Viviparidae (Mollusca: Gastropoda: Architaenioglossa)

The paper describes morphometric and allozymic differences among four European species of the family Viviparidae: Viviparus contectus (Millet, 1813), V. viviparus (Linnaeus, 1758), V. acerosus Bourguignat, 1862, and V. ater (Cristofori et Jan, 1832). Fourteen continuous biometrical characters were measured. Incremental discriminant-function analysis, principal-component analysis, and non-metric multidimensional scaling were applied to analysis of the morphometric differences. All the techniques confirmed a similar picture: a slight morphometric differentiation, with the variability ranges of the species overlapping. On the other hand, the allozymic differentiation, studied at 12 loci, eight of them intra and/or interspecific polymorphic, is much better marked, the intraspecific Nei's distances among the four V. contectus populations ranging from 0.0014 to 0.0397, mean 0.0166, and interspecific distances ranging from 0.2306 (V. ater–V. acerosus) to 0.9888 (V. contectus 2 and V. viviparus), mean 0.6871. The allele frequencies and genetic distances (Nei's distance and Cavalli-Sforza and Edwards’chord distance) were used to compute maximum likelihood, additive Fitch–Margoliash and ultrametric Fitch–Margoliash trees. All the trees presented a similar pattern, but the maximum-likelihood and additive trees, based on Cavalli-Sforza and Edwards’distance, seem to reflect the phylogeny best. The results are compared with the most parsimonious phylogenies inferred for radular, soft-part morphology and anatomy, and opercular data from other papers by us, and the inferred phylogenies are also compared. Although the inferred molecular and morphological phylogenies are little different in topology, the amount of evolution along the corresponding branches (measured as the number of changes averaged over all reconstructions) is very different, the value of correlation coefficient between the two phylogenies being statistically insignificant. The occurrence of interspecific hybrids is discussed, and the isolation-by-competition mechanism is postulated. The probable origin of V. viviparus from a founder population extremely restricted in number is stressed. The possible history of the group is briefly discussed. The species is suggested to have originated in an unusual habitat of melt water at a glacier foreland that could have promoted genotypic differentiation and sympatric speciation.     

GENETIC VARIATION IN SYMPATRIC AND ALLOPATRIC POPULATIONS OF HYBRIDIZING FRESHWATER SNAIL SPECIES(VIVIPARUS ATER AND V. CONTECTUS)

To estimate the geographical extent of introgression, we studiedthe genetic structure of sympatric and allopatric populationsof hybridizing freshwater snail species Viviparus ater and V.contectus in central Europe. Six allozyme loci which were variablein Lake Garda, Italy in a previous study (five nearly diagnosticloci between the two species and one highly polymorphic locusin V. contectus) were analyzed from ten sympatric locationsand four allopatric populations each for the two species. Presumablyintrogressed genes (low allele frequencies) were found fromat least one locus in seven out of the ten sympatric sites.These seven sites covered most of northern Italy. The data indicatethat introgression has occurred from Viviparus contectus toV. ater and vice versa. Therefore, there is a possibility ofwidespread introgression or mosaic zones in nature. However,we cannot rule out that the observed patterns are due to theshared ancestry. V. ater possessed low genetic variation (thejackknifed mean of Wright's F_ST±S.E. over four loci was0.041±0.004). On the other hand, V. contectus showedhigh genetic differentiation (the jackknifed mean of F_ST±S.E. over six loci was 0.546±0.166). Although introgressionmay have caused evolutionary changes in V. ater and V. contectus,it was not strong enough to level out the genetic differencesbetween the two species, which may have originated from isolationamong populations in V. contectus and a past bottleneck eventin V. ater. (Received 21 June 1996; accepted 31 January 1997)     

Genetic evidence for natural hybridization and apparent introgression between freshwater snail species (Viviparus ater and V. contectus)

We examined six allozyme markers and shell morphology to study gene flow between the naturally sympatric freshwater snail species Viviparus ater and V. contectus in Lake Garda, Italy, using offspring from experimental crosses and snails collected from natural populations. Hybrid offspring obtained from experimental crosses and hybrids collected from natural populations were heterozygous at four or five out of five diagnostic loci. Shell morphology was a poor predictor of the hybrid status of individual snails. Backcrossed offspring from experimentally bred hybrids and either of the parental species morphologically resembled the parental species. There was no evidence of segregation distortion at the six loci. Linkage analysis revealed one pair of linked loci (GPI and PNP). These cross experiments indicated a Mendelian type hybrid system in which gene introgression may occur. F₁ hybrids were found at four out of six sampling sites of Lake Garda, Italy. Local frequencies of F₁ hybrids ranged from 0% to 1.6% (estimated average = 0.74%) of the total population including both species. Alleles typical of V. ater were found at low frequencies in V. contectus at all six sampling sites. Alleles typical of V. contectus were found at low frequencies in V. ater at three out of six sampling sites. This is consistent with the hypothesis of introgression in both directions.     

黄鳝体内寄生胃瘤线虫的染色体核型及G-带分析

采用常规空气干燥法制片,对寄生于黄鳝(Monopterus albus)体腔内的胃瘤线虫(Eustrongylidesignotus)染色体核型进行分析。结果表明:胃瘤线虫体细胞有12条染色体,为二倍体,核型公式为2n=12=10 m+2 sm。由5对常染色体和1对性染色体组成,性别决定模式为XX-XY,其中X、Y和1～4号染色体都为中着丝粒染色体,5号为亚中着丝粒染色体。每对染色体都有特定的G-带带型。     

The karyotypes of the thorny catfishes <Emphasis Type="Italic">Wertheimeria maculata</Emphasis> Steindachner, 1877 and <Emphasis Type="Italic">Hassar wilderi</Emphasis> Kindle, 1895 (Siluriformes: Doradidae) and their relevance in doradids chromosomal evolution

We studied the karyotypes of two doradids, the rare and endangered Wertheimeria maculata and a derived Amazonian species, Hassar wilderi. Cytogenetic characterization was assessed using conventional staining (Giemsa), C-banding, and NOR banding. Both species had 2n = 58 chromosomes but differed in their chromosome formulae, 24 m + 14sm + 8st + 12a for W. maculata and 32 m + 16sm + 10st for H. wilderi. In W. maculata heterochromatin was mainly telomeric, and three chromosomes had a fully heterochromatic arm; in H. wilderi heterochromatin was also predominantly telomeric and evident in many more chromosomes. Hassar wilderi also presented one pair of homologues with a fully heterochromatic arm. In both species, nucleolar organizer regions were restricted to one pair of subtelocentric chromosomes. Assuming a basal position for W. maculata, we hypothesized that underlying conserved diploid and NOR-bearing chromosome numbers, chromosomal evolution in doradids has involved pericentric inversions and an increase of heterochromatic blocks.     

不同地理区域鲫鱼染色体银染核仁组织者的比较研究

本文对不同地理区域的鲫鱼(Carassius auratus)—滇池高背鲫、低背鲫、方正银鲫(C.auratusgibelio)的核型及核仁组织者NORs进行了比较研究,并对高背鲫来源作些初步探讨,结果如下: 1.低背鲫Carassius auratus (back low type):2n=100,22m+30sm+48t.st,NORs=4,出现于第5—6对亚中着丝粒染色体短臂。 2.滇池高背鲫Carassius auratus(back high type):2n=156,30m+46sm+80t.st,NORs=6,出现于第5—7对亚中着丝粒染色体短臂。 3.方正银鲫C.auratus gibelio:2n=162,32m+52sm+78t.st NORs=4,出现于第5—6对亚中着粒染色体短臂。     

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。     

Karyotype analyses in three Patagonian and S. Andean endemic genera ofNicotianeae (Solanaceae)

The somatic chromosomes and karyotypes of threeNicotianeae have been studied for the first time. All of them have 2n = 2x = 22 and symmetrical karyotypes.Benthamiella pycnophylloides has 9 m pairs + 1 sm pair + 1 st pair; pairs 2, 4, 5, and 11 bear microsatellites.Combera paradoxa andPantacantha ameghinoi have 9 m pairs + 2 sm pairs; pair 11 ofC. paradoxa is satellited, while pair 9 ofP. ameghinoi bears microsatellites and shows a pericentric inversion in heterozygous state in 20% of the seedlings. Results are compared with previous chromosome reports for the tribe. The cytological data support their present position in the family system. Besides,Benthamiella, Combera andPantacantha appear to be primitive genera ofNicotianeae, a comparatively advanced tribe within the family.Chromosome studies onNicotianeae (Solanaceae) 1.     

Karyomorphology of the genusLycopodium sensu stricto and relationships among species

Karyomorphological comparisons were made of six species of JapaneseLycopodium sensu stricto. There were no marked differences at interphase and prophase among the six species.Lycopodium annotinum had 2n=68 and the formula of its metaphase karyotype was 18m(median centromeric chromosomes)+12sm(submedian)+12st(subterminal)+26t(terminal).Lycopodium casuarinoides had 2n=68=16m+10sm+18st+24t,L. clavatum 2n=68=22m+12sm+18st+16t, andL. obscurum 2n=68=10m+22sm+20st+16t. Each of these species, which belong to different sections, displayed several karyomorphological differences. Among themL. casuarinoides differs largely from the others in its mean chromosome length, ratio of the longest chromosome to the shortest, and frequency of m+sm chromosomes. BothLycopodium complanatum andL. nikoense, belonging to sectionComplanata, had a common karyotype 2n=46=10m+12sm+18st+6t. This section displayed a low differentiation in its karyotype. In the wholeLycopodium s.s., the ratios of m+sm in a complement varied from 38 to 50%, being higher among pteridophytes.     

贵州两种黄脊蝗核型和C-带的比较研究

本文研究了贵州日本黄脊蝗 Patanga japonica Bolivar和印度黄脊蝗 P.Succincta Johansson的核型和c-带。结果表明：两种黄脊蝗的染色体数目均为2n(♂)=22+x.=23,全部为端着丝粒染色体;核型公式2n(♂)=2X=231,NF=23. 但日本黄脊蝗的染色体绝对长度总和(79.75±2.22μm)比印度黄脊蝗的(71.4 7±0.63μm)长;异染色质总量(35.65±0.14μm)比印度黄脊蝗的(10.76±0.11μm多;日本黄脊蝗的核型属“1B”核型,印度黄脊蜱的核型属“lc”核型。     

美丽硬仆骨舌鱼核型分析

美丽硬仆骨舌鱼(Scleropages formosus)是一种古老的具有很高经济价值的观赏鱼类。为了解该鱼的细胞遗传背景,采用胸腔注射植物血球凝集素(PHA)和秋水仙素的方法,以头肾为材料,空气干燥法制片,对美丽硬仆骨舌鱼的染色体进行了分析研究。结果表明,美丽硬仆骨舌鱼的二倍体染色体数目为50,核型公式为2n=2m+8sm+8st+32t,臂数(NF)为60。这一核型符合低等鱼类的基本特征,研究结果可为美丽硬仆骨舌鱼的种质标准和系统演化等提供基础数据。     

田螺科五种螺的核型研究

以早期胚胎细胞为材料,用火焰干燥法制片,对分布于我国湖北省武汉市近郊的常见田螺科(Viviparidae)五种螺的核型进行了分析。结果:两种圆田螺的染色体数和国外报道的同一属的种类的一致。而三种环棱螺的染色体数,则较国外报道的另两种的少得多。在铜锈环棱螺的核型中,其m组的第一对和sm组的第四对染色体上,具有明显的随体,出现频率甚高。     

Comparative karyology of species of the genera <Emphasis Type="Italic">Misgurnus</Emphasis> and <Emphasis Type="Italic">Cobitis</Emphasis> (Cobitidae) from the Amur River Basin in connection with their taxonomic relations and the evolution of karyotypes

Data are first provided on karyotypes of four species of Cobitidae from the Amur Basin: Misgurnus nikolskyi (2n = 50 = 10m + 4 sm + 36sta, NF = 64), Cobitis lutheri, (2n = 50 = 12m + 8sm + 30sta, NF = 70), C. choii (2n = 50 = 8m + 10sm + 8st + 24a, NF = 68), and C. melanoleuca (2n = 50 = 6m + 16sm + 28sta, NF = 72), and number of chromosomes in M. mohoity (2n = 50) and karyotypes of C. melanoleuca from the basin of the Don, Malyi and Bol’shoi Uzen rivers, and Selenga. These data are discussed in connection with problems of taxonomy of the studied genera, as well as the evolutionary relations of their karyotypes. On the basis of karyological differences between the populations of C. melanoleuca from different parts of the range, a new subspecies C. melanoleuca gladkovi subsp. nov. that inhabits waters of Europe is described.     

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。     

杂交鳢(斑鳢 ♀ ×乌鳢 ♂ )及其自交后代细胞核型初步分析

对杂交鳢(斑鳢♀×乌鳢♂)(Channa maculata ♀×C.argus ♂)及其自交后代的细胞核型进行了初步分析.结果表明,杂交鳢染色体数目为2n=45,核型公式为3m+4sm+6st+32t,染色体臂数(NF)为52;杂交鳢自繁后代群体存在两种染色体核型,一是染色体数目为45,核型公式为3m+4sm+6st+...     

基于荧光原位杂交的藜属植物核型分析

为精确地识别藜属植物染色体组的核型特征,该文研究了4种来自青海高原的野生藜属植物(灰绿藜、藜、菊叶香藜及杂配藜)和1种从美国引进的栽培藜麦品种PI614932-HX(3)基于染色体荧光原位杂交(rDNA FISH)的核型。利用5S rDNA和45S rDNA对5种藜属植物有丝分裂中期的染色体进行FISH研究。藜属植物的核型分析结果表明:(1)藜属植物中存在二倍体(2n=2x=18)和四倍体(2n=4x=36)两种倍性,藜麦和灰绿藜为四倍体,其余3种为二倍体。(2)藜麦、灰绿藜、藜、菊叶香藜及杂配藜的核型公式分别为2n=4x=36=34m(2AST)+2sm,2n=4x=36=32m(4AST)+4sm,2n=2x=18=16m(4AST)+2sm,2n=2x=18=18m及2n=2x=18=16m+2sm。(3)染色体由大部分的中部着丝粒染色体(m)和少部分近中部着丝粒染色体(sm)组成。(4)核型类型除了菊叶香藜为1B以外,其余均属于2B类型。(5)在藜麦、灰绿藜及藜中具有分布位置不同、数量不等的双随体。5S rDNA、45S rDNA FISH结果表明:(1)藜麦和灰绿藜的染色体上存在2对5S rDNA位点和1对45S rDNA位点,藜、杂配藜的染色体上存在1对5S rDNA位点和1对45S rDNA位点,菊叶香藜的染色体上只存在1对5S rDNA位点。(2)5S rDNA和45S rDNA位点均位于染色体的短臂上。该研究首次获得了藜属植物基于5S rDNA和45S rDNA荧光原位杂交核型,为藜属植物亲缘关系研究和细胞生物学研究提供了分子细胞遗传学依据。     

DENSITY AND GROWTH OF FRESHWATER PROSOBRANCH SNAILS (BITHYNIA GRAECA AND VIVIPARUS CONTECTUS)IN RELATION TO WATER CHEMISTRY IN SERRES, NORTHERN GREECE

Population density and daily rate of growth in relation to waterchemistry in the prosobranch gastropods Bithynia graeca andViviparus contectus were studied in the artificial Lake Kerkiniand in the marshes of Strymonas River upstream of its entryto Lake Kerkini (Serres Macedonia, N. Greece) respectively.PO4-Pconcentration proved to be the most significant hydro-logicalparameter for the density and the rate of daily growth in B.graeca. The water variable which proved to be significant forthe density of V. contectus was dissolved oxygen.B. graeca iscapable of true tissue-degrowth (40% loss of tissue dry mass)with low mortality rate during winter. (Received 24 March 1994; accepted 9 January 1995)     

中国西南地区6种植物的核型研究及其系统学意义

采用植物细胞学研究方法对主要采自中国西南地区横断山的6种植物:扁核木(Prinsepia utilis)、小叶金露梅(Potentilla parvifolia)、峨眉繁缕(Stellaria omeiensis)、金铁锁(Psammosilene tunicoides)、山卷耳(Cerastium pusillum)和独尾草(Eremurus chinensis)进行染色体数目和核型研究。研究表明:(1)6个种的核型公式和不对称性如下:扁核木2n=2x=30=1M+20m+9sm,2A;小叶金露梅2n=2x=28=21m+7sm,2B;峨眉繁缕2n=8x=72=1M+71m,1B;金铁锁在同居群下有倍性变化,2n=2x=14=14m,1A和2n=4x=28=28m,1A;山卷耳2n=2x=24=24m(2sat),1A;独尾草2n=2x=14=2m+2sm+8st+2t,4B。(2)讨论了染色体资料在这些物种分类和系统上的意义,支持扁核木为李亚科下的扁核木属;位于委陵菜属木本系的小叶金露梅主要以二倍体和四倍体为主,而草本系的委陵菜属植物多为多倍体。(3)该研究首次报道峨眉繁缕为八倍体,是繁缕属发现的最高倍性的物种;对比金铁锁属与蝇子草属的染色体研究发现,金铁锁属可能是由它们的共同祖先通过非整倍化产生;该研究首次发现山卷耳存在染色体数目2n=24的情况,且有1对随体;独尾草的研究进一步证明该物种可能为二型核。     

Karyomorphological studies onWoodwardia sensu lato of Japan

Karyomorphological comparisons were made of five species of JapaneseWoodwardia. There were no marked differences at interphase and prophase among the five species.Woodwardia japonica, W. prolifera, andW. unigemmata were diploid with 2n=68 and the formulas of their metaphase karyotypes uniformly 4m(median centromeric chromosomes)+12sm(submedian)+52(st+t)(subterminal and terminal).Woodwardia orientalis was tetraploid with 2n=136 and 8m+24sm+104(st+t), and the ratio of each chromosomal type to total complement was identical to that of three diploid species. These four species had several characteristics in common:x=34, the longest chromosome of sm, and a mean chromosome length over 3.0 μm. AlthoughWoodwardia orientalis showed some similarity toW. prolifera, it seems to be an allotetraploid which originated by chromosome doubling of a hybrid ofW. prolifera and a diploid species as yet karyomorphologically unknown.Woodwardia kempii was tetraploid with 2n=124 and 8m+24sm+92(st+t), and differed from the others in havingx=31, the longest chromosomes of t, and a mean chromosome length under 3.0 μm. This species has been classified as an independent genus,Chieniopteris, and our karyomorphological study supports this treatment.