Cytogenetics of the European plethodontid salamanders of the genus Hydromantes (Amphibia,Urodela)

A karyological analysis was carried out on different European species of the genus Hydromantes (Plethodontidae). All the species examined share the same chromosome number (2n=28) and, with the exception represented by pair XIV, morphologically similar karyotypes. While the karyotypes display a similar distribution — mainly centromeric and pericentric — of C-heterochromatin, quantitative variations in pericentric heterochromatin are observed among species. In the continental species Hydromantes italicus and ambrosii as well as in the eastern Sardinian species imperialis, flavus and specie nova, pair XIV consists of heteromorphic sex chromosomes of the XX/XY type. It is proposed that the differentiation of the Y might have taken place through the occurrence of a structural rearrangement, such as a pericentric inversion, starting from a hypothetical, homomorphic pair XIV. A sex-related heteromorphism is not found in the western Sardinian species H. genei. A further karyological differentiation among these species concerns the position of the nucleolus organizing region (NOR), which is located on chromosome XII (H. italicus and ambrosii) or on chromosome X, close to the centromere (H. genei, H. imperialis and H. specie nova), or in an intercalary position (H. flavus). The location and the number of the 5 S DNA sites have been conserved during species divergence. On the basis of these karyological data, as well as of results obtained through a preliminary restriction enzyme analysis of the ribosomal and genomic DNAs, the phyletic relationships among the European Hydromantes species are discussed.     

KARYOTYPIC DATA ON NORTH AND CENTRAL AMERICAN ZAMIACEAE (CYCADALES) AND THEIR PHYLOGENETIC IMPLICATIONS

Chromosome numbers and karyotypes of species from four American Zamiaceae (Cycadales) are reported. Zamia shows interspecific and intraspecific chromosome variation, whereas Microcycas, Ceratozamia, and Dioon have constant karyotypes within each genus. In Zamia, all karyotypes have the same number of submetacentric and acrocentric chromosomes, but they differ in the number of metacentric and telocentric chromosomes. Centric fission of metacentric chromosomes is proposed to explain the karyotypic variation in this genus. Zamia shows karyological relationships with Microcycas and Ceratozamia, whereas Dioon appears very distinct from the other American cycad genera. Affinity among Zamia, Ceratozamia, and Microcycas karyotypes and distinctiveness of Dioon karyotypes are supported by comparative analysis of phenotypic characters in the four genera.     

Chromosomal apparatus of trematodes of the general Diplostomum and Tylodelphys (Strigeidida, Diplostomatidae) and its taxonomic significance

The chromosomal apparatus of three species of trematodes of Diplostomum (D. spathaceum, D. indistinctum, D. mergi) and one species Tylodelphys (T. clavata) is described. It has been suggested that karyological investigations can be used for taxonomic purposes. The opinion has been expressed that the number of chromosomes in the karyotype of these trematodes plays no taxonomic role. Of great taxonomic significance are the size and morphology of chromosomes. Differences in karyotypes of trematodes belonging to different species and genera were revealed by these characters. The absence of close dependence between morphology of adult and specific peculiarities of karyotypes in species of the same genus enables in some cases the use of chromosomal apparatus as a most reliable criterion for a differentiation of close species.     

Chromosomes of the liver fluke, Clonorchis sinensis

A karyological study was carried out in order to compared the chromosome numbers, chromosome morphologies and karyotypes of the oriental liver fluke, Clonorchis sinensis (Trematoda: Opisthorchiidae), collected from Korea and China. Chromosome preparations were made by means of air-drying method. The chromosome number was 2n = 56 in both Korean and Chinese flukes, and chromosomes were divided into two groups based on this size; consisting of 8 pairs of large and 20 pairs of small chromosomes. However, the karyotypes showed some differences between Korean and Chinese flukes. The karyotype of liver flukes from Korea consisted of three metacentric pairs, one meta-/submetacentric pair, 16 submetacentric pairs and eight subtelocentric pairs of chromosomes. On the other hand, liver flukes from China consisted of two metacentric pairs, two meta-/submetacentric pairs, 16 submetacentric pairs and eight subtelocentric pairs of chromosomes.     

Chromosomes of thecercopithecus aethiops species group:C. aethiops (Linnaeus, 1758),C. cynosurus (Scopoli, 1786),C. pygerythrus (Cuvier, 1821), andC. sabaeus (Linnaeus, 1766)

The banded karyotypes of 34 monkeys of known geographic origin and belonging to the Cercopithecus aethiops group of species (C. aethiops, C. pygerythrus, C. cynosurus, C. sabaeus) show that chromosome evolution in this group is highly conservative. All species have 2n =60 chromosomes with very similar chromosome banding. However, differences were found both within and between species. A polymorphism of the NOR area of the “marked” chromosome pairs was found in all taxa (9 of 34 animals). All individuals referred to C. sabaeus,from both West Africa and the Barbados, are characterized by having highly positive G- and C- banded terminal sequences on chromosomes 7,10,12, and 14. Outgroup comparisons with other primates and a parsimony analysis suggest that these terminal bands are derived and are probably good taxonomic and phylogenetic indicators. Moreover, chromosome 18 is variable both between and within species in G banding and in short-arm length. The existence of within-species variation in karyotypes suggests that karyological comparisons must be based on adequate samples that include specimens coming from all the major geographic populations of the species concerned.     

Karyotypic studies on species of Phaseolus (Fabaceae: Phaseolinae)

Ten karyotypes of Phaseolus were analyzed. Possible directions of karyological evolution of those species are suggested. All species studied have karyotypes composed exclusively of metacentric and submetacentric chromosomes, except P. filiformis with all metacentrics, and P. chiapasanus with one pair of subtelocentric chromosomes. Secondary constrictions and satellites are common among species studied. Phaseolus leptostachyus, P. micranthus, and P. macvaughii are considered as aneuploids with 2n= 20, whereas the rest of the species have 2n= 22.     

Structural heterozygosity in Scilla hyacinthoides L. and Scilla amoena L. (Liliaceae). Karyological analysis

Abstract

A karyological analysis carried out in Scilla hyacinthoides L. and Scilla amoena L. on material collected in the Botanical Garden of Cagliari (Sardinia), has shown the presence of heterozygous karyotypes in the two species. The chromosome number of S. hyacinthoides was found to be 2n = 20, while the chromosome number of S. amoena was 2n = 12, in accordance with the data found in the literature. Both the observed karyotypes show clear structural alterations, especially evident in one pair of clearly heteromorphic chromosomes. The analysis of the karyotypes seem to exclude a hybrid origin of the material examined and it is probable that such karyotypes may be the result of various structural re-arrangements, still evolving and aiming at a cytogenetic stabilization of the genus Scilla.     

七种木蓝属植物的染色体研究

本文采用根尖压片法对豆科（Leguminosae）木蓝属（IndigoferaL.）植物的7个种：多花木蓝（Indigofera amblyantha Craib）、河北木蓝（I.bungeana Walp.）、滇木蓝（I.delavayi Franch.）、腺毛木蓝（I.scabrida Dunn）、四川木蓝（I.szechuensis Craib）、刺序木蓝（I.silvestrii Pamp.）、尖叶木蓝（I.zollingeriana Miq.）的染色体数目和核型进行了研究。结果表明：除了尖叶木蓝染色体数目为2n=4x=32（四倍体）外,其余6种木蓝的染色体数目均为2n=2x=16（二倍体）。尖叶木蓝和刺序木蓝核型分类为2A型,其余5种木蓝的核型均为1A型。种间核型差异很小。供试种主要包含中部着丝点区染色体。滇木蓝、腺毛木蓝、刺序木蓝、四川木蓝和尖叶木蓝的核型分析为首次报道。     

A new insight into Serjania Mill. (Sapindaceae, Paullinieae) infrageneric classification: a cytogenetic approach

Serjania (Sapindaceae, Paullinieae) comprises about 230 species, and currently two infrageneric classifications have been proposed but both are difficult to apply. This work tested which infrageneric classification fitted better in relation to cytogenetic traits added to the main morphological features used by the authors of the subgenus arrangements to gain an insight into the evolutionary karyotype relationships. In order to test the relationship between karyotypes and the systematics of this genus, the karyotypes of five species of Serjania belonging to five different sections (sensu Radlkofer) were described. Known karyological information on 26 species was used to complement the results. With these data, a cluster analysis was set up to test which infrageneric classification fitted better. In addition, a principal component analysis (PCA) was performed to examine the relevance of the traits in the subgenus classification. All the karyotypes analyzed (including new as well as previous records) had 2n?=?24 chromosomes, and the karyotypes were asymmetrical: submetacentric and metacentric chromosomes were common, whereas telocentric chromosomes were rare. The PCA revealed seven principal components, the first two explained 52?% of the total variation, and the last ones were related to all the karyotypic features studied. The phenogram obtained reflected a scarce fitting into both infrageneric classifications, with only 3 sections of the 12 proposed by Radlkofer and two of the six sections proposed by Acevedo-Rodríguez being represented. Finally, regarding karyotype evolution, the constancy of chromosome number and the variation in the length of the complement suggest that structural chromosome changes would have played a leading role.     

Selachian cytogenetics: a review

The karyotype of Chondrichthyes is still the least investigated among vertebrates. Over the last 40 years, the karyotypes of 63 out of the 1100 known species (5.73%) have been described in literature, namely seven squalomorph, one squatinomorph, 20 galeomorph, 33 batoid and two holocephalian species. Generally, the diploid number ranges from a minimum of 28 to a maximum of 106 elements, with more frequent values observed between 50 and 100 chromosomes. None of the four superorders is characterized by a peculiar chromosome set or morphology; the number of uniarmed and biarmed elements is variable in all the karyotypes, and microchromosomes are often present. The general trend in all groups seems to be a progressive reduction of the telocentric chromosome number in the most specialized species, followed by the loss of the microchromosomes. Polyploidy, followed by diploidization events and Robertsonian rearrangements, might have played a key role in the karyological evolution of elasmobranch fish. Chondrichthyes have the largest genome sizes among vertebrates, with the exception of dipnoans and urodeles. In the whole class, the species examined vary greatly in size, from 3 to 34pg/N: the lowest values have been observed in holocephalians, while galeoids and batoids have a DNA amount ranging from 5 to 15 pg/N. Squaloids show heterogeneous DNA amounts, ranging from 8 to 34 pg/N. In more recent years, karyological studies have provided new data on the characterization of selachian karyotypes by C-banding, NOR staining, restriction enzymes in situ digestion and FISH with specific DNA probes, such as telomeric and SINE sequences.     

Karyotype polymorphism in the cycad Zamia loddigesii (Zamiaceae) of the Yucatan Peninsula, Mexico

The cycad %amia loddigesii Miq. forms a morphologically variable complex on the Yucatan peninsula, Mexico. Several diploid chromosome numbers have been found in the species: In = 17, 24, 25, 26 and 27. Differing karyotypes and chromosome numbers were found in individuals of the same population and die karyotypes differ widely in numbers of metacentric and telocentric chromosomes present. Centrometric fission as well as pericentric inversions and unequal translocations are suggested to be the probable mechanisms for this karyotype variation. There appears to be a correlation between high chromosome number and increasing dryness of the habitats. Coupled with the strongly asymmetrical karyotypes, this suggests that karyotype evolution in Z- loddigesii is recent.     

Karyological analysis of two allopatric populations of planarian Polycelis felina (Daly.) in Croatia

The results of preliminary karyological investigations of two geographically distant and morphologically slightly different Polycelis felina (Daly.) populations from central Croatia are reported. The results have shown that individuals of both populations are diploids, with the same chromosome number in their neoblasts (2n=18). Their karyotypes were composed of nine chromosome pairs, three of them are metacentric and the other six are submetacentric. Statistical evaluation of data indicated that both populations of Polycelis felina (Daly.), despite minor differences observed between them, belong to the same karyological biotype.     

A cytogenetic study on the rodent tapeworm Rodentolepis myoxi

The karyotype of glirid tapeworm Rodentolepis myoxi (Rudolphi, 1819) (Cestoda: Hymenolepididae) comprises six pairs of small bi-armed chromosomes (2n = 12). All pairs of chromosomes possess uniform morphology, i.e. metacentric, submetacentric or meta-submetacentric types of structures. The formula of the karyotype structure is n = 2m + 1m-sm + 3sm. The absolute chromosome length ranges from 3.78 to 2.00 microm. The mean total length of the haploid complement is 15. 98 microm. The first pair (group A) is the largest, pairs 2 and 3 can be grouped into group B while pairs 4-6 are smaller and can be classified as group C. The number of chromosomes of R. myoxi is the same for the congeneric species, however, karyological characteristics differ from all recently known karyotypes of rodent hymenolepidids.     

Karyotypic characterization of three weevil species (Coleoptera: Curculionidae, Brachyderini)

Karyotypes of three species, Brachyderes incanus, Brachysomus setiger and Paophilus afflatus, belonging to the tribe Brachyderini, were studied using C-banding technique. The species share the same chromosome number 2n = 22 and meioformula n = 10+Xy(p) at all metaphase 1 plates of spermatid division. Some differences between karyotypes were observed in terms of centromere positions and C-band sizes. Most chromosomes are meta- or submetacentric and form a graded series in respect to length. The chromosomes resemble one another in having a rather small amount of heterochromatin restricted to the pericentromeric region and visible as dark stained blocks mainly during early stages of nuclear division. Only in Brachyderes incanus do larger bands occur at mitotic metaphase and diakinesis. These cytogenetic data are in agreement with karyological findings obtained in other species of Brachyderini so far examined.     

Karyomorphology, heterochromatin patterns and evolution in the genus Ophrys (Orchidaceae)

Karyotype structures and heterochromatin distribution in representative taxa of the genus Ophrys are compared, based on Feulgen-stained and banded somatic metaphase chromosomes. The karyotypes of Ophrys iricolor , O. lupercalis , O. caesiella , O. lutea , O. lunulata , O. x. tardans , O. apifera , O. praecox , O. lacaitae and O. insectifera are described for the first time. The karyological analyses indicate the relationships among the species with respect to asymmetry indices and heterochromatin content. Chromosomal differences have been helpful in clarifying the taxonomic position of Ophrys species that do not have clear affinities. The representative species of Araniferae , Fuciflorae and Ophrys sections exhibited the most asymmetrical karyotypes, while chromosome complements of the O. fusca–O. lutea group, of O. tenthredinifera and of O. bombyliflora proved to be less asymmetrical. Weakly heterochromatic chromosomes, with heterochromatin present mostly in thin centromeric bands, characterize Ophrys C-banded karyotypes. Chromomycin A₃ (CMA) staining revealed that the analysed species exhibit a weak pattern of CMA⁺ bands at centromeric, intercalary or telomeric regions. No DAPI bright blocks were observed. The significance of the karyological data is discussed with regard to the relationships between the analysed species. © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 87–99.     

天南星科斑龙芋属植物的核型研究

报道了天南星科（Araceae)斑龙芋属（Sauromatum)两种植物的型,它们的静止核均为渐变型,分裂前期染色体均为中间型,体细胞中期染色体均为2n=26,核型分别为：斑龙芋（S.venosum)2n=2x=26=14m 12sm;高黎贡山斑龙芋（S.gaoligongense)2n=2x=26=10m 12sm 4st,其中高黎南山斑龙芋的染色体数目和核型为首次报道。本文还就斑龙芋属的分类地位进行了初步讨论,认为在尚未进行更详细的、多方面的综合研究之前,仅从一些形态上的相似性就匆忙将斑龙芋属归并到犁头尖属是值得商榷的,并从珠芽和细胞学两方面的特性推断属与半夏属可能有较近的亲缘关系。     

国产四种绢藓属植物的核型研究

国产苔藓植物的核型研究,目前尚未见到任何报道。本文对中国产绢藓属4种植物进行了核型研究。观察了配子体有丝分裂中期的染色体和异染色体。4种植物的染色体数目均为11。钝叶绢藓(E．obtusatus),密叶绢藓(E．compressus),东亚绢藓(E．okamurae),的核型公式为K(n)=11＝2V(H)+2J+6(4v+2i)+m(h),陕西绢藓(E.giraldii)为K(n)＝11＝2V(H)+V+2J+5(3v+2i)+m(h)．4种植物的核型均为首次报道。     

Chromosomal evolution and speciation in the Gyratrix hermaphroditus species complex (Platyhelminthes,Kalyptorhynchia): karyometric and morphological analyses of fifteen fresh-water populations from Western Europe

Fifteen fresh-water populations of the Gyratrix hermaphroditus species complex from Western Europe (Italy, Spain, France) were karyometrically analysed. All shared the same chromosome number 2n = 4. Three distinct karyotypes were recognized on the basis of the different values of the centromeric index of chromosome 2, respectively metacentric, intermediate between meta- and submetacentric, and sub-telocentric. The morphology of chromosome 1 (an isobrachial metacentric) and the length ratio of chromosomes were on the contrary constant in all the populations investigated.Differences in the size of male cuticular organs were observed accompanying the karyological differentiation.The fifteen populations are interpreted as representing at least three sibling-species.Chromosomal evolution and phylogenetical relationships with the marine species of the Gyratrix hermaphroditus complex are discussed.     

Convergence and divergence between morphology and karyology in related species of the genus Vicia]

Karyological polymorphism is generally the rule in related species of genus Vicia, as has been frequently shown in many entities of its comprehensive species; therefore a correspondence of phenotypic and karyotypic characters is rather rare. Two cases are described here, in which both external morphological and internal karyological features, are correlated. These data have been obtained through biometric and karyotypic studies, carried out both on the perennials V. onobrychioides and V. altissima, and on the annuals V. villosa ssp. varia and V. benghalensis. In both perennials the chromosomes were rather long, the nucleolar constriction was on the longest couple of chromosomes, and even the satellite was of the same type; in both annuals the chromosomes were short, the nucleolar constriction was on the shortest couple of chromosomes, and the satellite was large in comparison to the arm to which it was connected. These similarities of the karyotypes are important because they may make easier a possible experimental cross-breed of the abovementioned entities.