C-banded chromosomes of the genus Bembidion Latr. (Coleoptera, Carabidae)

The C-banding pattern of Bembidion punctulatum, B. varium, B. varicolor, B. ascedens, B. tibiale, B. ustulatum, B. decorum, and B. modestum are presented. All examined species have a symmetrical karyotype with meta- and submentacentric chromosomes and meioformula n=11+XY. All of them have an achiasmatic spermatogenesis in common. The present data confirm earlier studies indicating a considerable morphological and numerical stability of the Bembidiini karyotype. The C-banding showed the existence of heterochromatin in the paracentric regions of chromosomes, and also 2-3 intercalar C-positive segments were observed. The Y chromosome is entrely euchromatic. The C-banded karyotype of the analysed species in genus Bembidion has large heterochromatin segments on chromosomes, an exception in Coleoptera.     

First report on C-banding and fluorescent banding in species of Dieuches (Rhyparochrominae: Lygaeidae: Heteroptera)

Although the karyotypes of twelve species of Dieuches Dohrn, 1860 belonging to Rhyparochrominae have been described so far, there is no information about heterochromatin and its characterization in terms of base composition for any of the species. In the present paper, C-banding and fluorescent banding have been applied for the first time to three species of Dieuches : D. uniguttatus, D. insignis (2n = 12 = 8A + 2m + XY) and D. coloratus (2n = 14 = 10A + 2m + XY). Dieuches uniguttatus and D. insignis show distinct terminal C-bands along with a few interstitial bands in all the autosomal bivalents, whereas in D. coloratus , one autosomal pair is almost completely heterochromatic, three show C-positive bands while one is totally euchromatic. The sex chromosomes too show heterogeneity in distribution of C-heterochromatin among three Dieuches species. Characterization of heterochromatin in D. uniguttatus and D. insignis using DAPI/CMA₃ staining reveals that in D. uniguttatus , C- heterochromatin blocks of all the autosomal bivalents, which are predominantly A–T rich, whereas in D. insignis , these are rich both in A–T and G–C. In D. uniguttatus, sex chromosomes X and Y have localized G–C rich regions whereas in D. insignis , these are scattered in X and absent in Y. As variations in the heterochromatin represent the main source of karyological differentiation among and within species, it seems that there occurred extensive redistribution of heterochromatin within the complement as the three species evolved. There is need for cytological details of more species to understand evolutionary aspects in the genus Dieuches .     

C-heterochromatin and extra (B) chromosome distribution in six species of the Nabis (Heteroptera, Nabidae) with the modal male karyotype 2n = 16 + XY

The basic male karyotype of the six Nabis species (Heteroptera, Nabidae) is confirmed as being 2n=16+XY. The chromosomes are holokinetic while male meiosis is achiasmatic. The sex chromosomes undergo postreduction and in second metaphase show distance pairing, registered in all nabid species examined so far. Using C-banding technique for the first time in the family Nabidae, the heterochromatin was revealed on chromosomes of six species. The species showed different amount and distribution of C-heterochromatin. Only in Nabis (Dolichonabis) limbatus did the C-bands distribution make possible the identification of every chromosome pair in the karyotype. In other species, C-bands were found in some of the autosomes and the X, localized either interstitially or at telomeres. Only the Y usually showed relative stability ofthe C-banding pattern. In four of six species, extra (B) chromosomes were observed and their behaviour in meiosis described.     

Patterns of chromosome banding in four nabid species (Heteroptera, Cimicomorpha, Nabidae) with high chromosome number karyotypes

Male Nabis (Aspilaspis) indicus (St?l), N. (A.) viridulus Spinola, Himacerus (Himacerus) mirmicoides (O. Costa) (2n=32+XY) and Prostemma guttula (Fabricius) (2n=26+XY) were studied using C-banding, silver nitrate staining and base-specific fluorochrome (DAPI and CMA(3)) staining. N. indicus differed from N. viridulus in distribution pattern of C-bands, which were telomeric in the former while interstitial in the latter. H. mirmicoides showed interstitial C-bands in the majority of autosomes. P. guttula had no conspicuous C-bands in other chromosomes, but only in the Y, which was totally heterochromatic. C-heterochromatin was labelled with DAPI, indicating that it was AT-rich. In every species, both X and Y chromosomes were NOR-bearing, and the NOR regions were GC-rich. In H.mirmicoides and P. guttula, NORs showed sub-median location in the X and distal in the Y, such a pattern being probably common in Nabidae. The present paper provides new information on the genome organization and new cytological markers useful for a better insight into karyotype evolution of nabid species.     

C-banding and DNA content in three species of Belostoma (Heteroptera) with large differences in chromosome size and number

C-banding was carried out on Belostoma elegans (2n=26+X₁X₂Y) (), B. micantulum (2n=14+XY) () and B. oxyurum (2n=6+XY) () (Belostomatidae, Heteroptera). The C-bands always have a telomeric localization and no interstitial bands were detected. An inverse relationship between chromosome size and chromosome number exists, and besides, an inverse relationship between chromosome size and the size of the C-bands was observed. The DNA content was determined in all three species. B. elegans has a C content of 1.55±0.06 pg, B. micantulum has 0.88±0.04 pg and B. oxyurum had 0.53±0.04 pg.Considering the male meiotic characteristics, the chromosome complement and the results of C-banding and DNA content, the karyotype of B. oxyurum probably originated through autosomal fusions. The karyotype of B. micantulum and B. elegans could have originated through autosomal fusions or fragmentations respectively; with the information available up to now it is not possible to discard any of the two pathways.     

芥蓝和结球甘蓝染色体组型及C-带带型的研究

本文用改进的染色体标本制片技术,研究了芥蓝和结球甘蓝的染色体组型和 C-带带型。两种植物的二倍体均由4对中着丝粒、5对亚中着丝粒染色体组成,其中一对为随体染色体。芥蓝和结球甘蓝具有统一的染色体组型公式:2n=18=8m+10sm(2SAT),但两者的某些染色体在编号顺序上有差异。在结球甘蓝中观察,到4种不同形态的随体。用 BSG C-带方法得到 C-带带型,带型公式,芥蓝为2n=18=CITS 型=10C+2CI_++4CT~++2CS;结球甘蓝为2n=18=CITS 型=8c+2CI_++6CT~++2CS。某些带纹具多态性和杂合性。本文从染色体水平上讨论了芥蓝与甘蓝的亲缘关系。     

Meiotic karyotypes in males of nineteen species of Psylloidea (Hemiptera) in the families Psyllidae and Triozidae

Meiotic karyotypes in males of 16 species (assigned to 9 genera and 7 subfamilies) ofthe family Psyllidae and 3 species (assigned to 3 genera of the subfamily Triozinae) of the family Triozidae are described for the first time. The first data on the genus Ligustrinia are presented. All the species were shown to exhibit the modal karyotype for psyllids, 2n = 24 + X, except Bactericera nigricornis and Arytainilla spartiophila, in which 2n = 24 + XY and 2n = 22 + X were found, respectively. The karyotype of Ctenarytaina eucalypti (Psyllidae, Spondyliaspidinae) was reinvestigated, and the karyotype 2n = 10 + X, characteristic of Spondyliaspidinae, was revealed. The karyotypes ofStrophingia fallax, S. arborea, and Craspedolepta topicalis were studied using the C-banding technique.     

Heteromorphic sex chromosome system with an exceptionally large Y chromosome in a catfish Steindachneridion sp. (Pimelodidae)

The chromosomes and banding patterns of Steindachneridion sp., a large catfish (Pimelodidae), endemic to the Igua?u River, Brazil, were analyzed using conventional (C-, G-banding) and restriction enzyme banding methods. The same diploid number (2n = 56) as in other members of the genus and the family was found but the karyotype displayed an XX/XY sex chromosome system. The X chromosome was the smallest submetacentric, while the Y was the largest chromosome in the karyotype. Meiotic analysis showed 27 autosomal bivalents plus one heteromorphic XY bivalent during spermatogenesis. Sex chromosomes had no particular pattern after C-banding but G- and restriction enzyme bandings showed specific banding characteristics. The present finding represents the first report of a well-differentiated and uncommon sex chromosome system in the catfish family Pimelodidae.     

Studies on the Karyotypes and C-Banding Patterns of Chinese Kale (Brassica alboglabra ) and Cabbage ( B. oleraca var.eapitata)

The karyotypes of B. alboglabra and B. oleracea var. capitata were analyzed by an improved technique. The diploids of the two species consist of 4 pairs of metacentric and 5 pairs of submetacentric chromosomes (1 pair of satellites). The karyotype formula is summarized as 2n =18=8m+10sm (2 SAT). But the relative positions of some similar chromosomes are different in the genomes. Four kinds of satellites were observed in B. oleracea var. capitata. C-banding patterns were obtained by BSG C-banding. The C-banding formula is: 2n= 18=CITS pattern = 10C+2CI+ +4CT+ +2CS for B. alboglabra, and 2n= 18=CITS pattern = 8C+2CI +6CT+ + 2CS for B. oleracea var. capitata. The relationship between B. alboglabra and B. oleracea was discussed based on the chromosomal characteristics.     

On the robertsonian polymorphism found in the Japanese raccoon dog (Nyctereutes procyonoides viverrinus)

Karyotypes of 39 Japanese raccoon dogs (NPV) which appeared in the literature and of 7 previously unreported specimens were examined. Thirty four individuals showed the standard karyotype 2K = 26M + 10A + (M)X + (A)Y + Bs (2n = 38 + Bs), where Bs are supernumerary chromosomes. The remaining 11 individuals had 2K = 25M + 12A + XY + Bs (2n = 39 + Bs) and one was 2K = 23M + 16A + XY + Bs (2n = 41 + Bs). The G- and C-banding analyses of both somatic and germ cells revealed that these karyotypes with odd numbers are heterozygous (M/A) for a single Robertsonian rearrangement of chromosomes 2, 5, 6, 8, or 11, and one is M/A heterozygous for three autosomes: 5, 6, and 11.     

First evidence of polyploidy in Psylloidea (Homoptera,Sternorrhyncha): a parthenogenetic population of <Emphasis Type="Italic">Cacopsylla myrtilli</Emphasis> (W. Wagner, 1947) from northeast Finland is apomictic and triploid

This paper reports results of the first cytogenetic study of parthenogenetic psyllids, carried out on an asexual population of the holarctic species Cacopsylla myrtilli W. Wagner from northeast Finland. Preparations of mature eggs extracted from females revealed 39 univalent chromosomes in prophase and metaphase cells. Hence, female meiosis is of apomictic type and replaced by a modified mitosis. The karyotype consists of 3n = 39 (36 + XXX). Clearly, the population is triploid, the haploid number being n = 12 + X as characteristic of the genus Cacopsylla as a whole. As typical for Psylloidea, the chromosomes are holokinetic, only slightly varying in size and without any visible markers, rendering impossible the precise identification of triplets of homologous chromosomes in the triploid complement. The distribution of bisexual and parthenogenetic populations of C. myrtilli throughout the world is briefly given, and a possible origin of the triploid parthenogenetic population is discussed.     

The Origin of the Achiasmatic XY Sex Chromosome System in Cacopsylla peregrina (Frst.) (Psylloidea, Homoptera)

The status of an extra univalent, if it is a B chromosome or an achiasmatic Y chromosome, associating with the X chromosome in male meiosis of Cacopsylla peregrina (Frst.) (Homoptera, Psylloidea) was analysed. One extra univalent was present in all males collected from three geographically well separated populations, it was mitotically stable, and showed precise segregation from the X chromosome. These findings led us to propose that the univalent represents in fact a Y chromosome. The behaviour of the X and Y chromosomes during meiotic prophase suggested that their regular segregation was based on an achiasmatic segregation mechanism characterised by a 'touch and go' pairing of segregating chromosomes at metaphase I. To explain the formation of the achiasmatic Y within an insect group with X0 sex chromosome system, it was suggested that the Y chromosome has evolved from a mitotically stable B chromosome that was first integrated into an achiasmatic segregation system with the X chromosome, and has later become fixed in the karyotype as a Y chromosome.     

C-Banding/DAPI and in situ hybridization reflect karyotype structure and sex chromosome differentiation in Humulus japonicus Siebold & Zucc

Japanese hop (Humulus japonicus Siebold & Zucc.) was karyotyped by chromosome measurements, fluorescence in situ hybridization with rDNA and telomeric probes, and C-banding/DAPI. The karyotype of this species consists of sex chromosomes (XX in female and XY1Y2 in male plants) and 14 autosomes difficult to distinguish by morphology. The chromosome complement also shows a rather monotonous terminal distribution of telomeric repeats, with the exception of a pair of autosomes possessing an additional cluster of telomeric sequences located within the shorter arm. Using C-banding/DAPI staining and 5S and 45S rDNA probes we constructed a fluorescent karyotype that can be used to distinguish all autosome pairs of this species except for the 2 largest autosome pairs, lacking rDNA signals and having similar size and DAPI-banding patterns. Sex chromosomes of H. japonicus display a unique banding pattern and different DAPI fluorescence intensity. The X chromosome possesses only one brightly stained AT-rich terminal segment, the Y1 has 2 such segments, and the Y2 is completely devoid of DAPI signal. After C-banding/DAPI, both Y chromosomes can be easily distinguished from the rest of the chromosome complement by the increased fluorescence of their arms. We discuss the utility of these methods for studying karyotype and sex chromosome evolution in hops.     

C-bands on chromosomes of 32 beetle species (Coleoptera: Elateridae, Cantharidae, Oedemeridae, Cerambycidae, Anthicidae, Chrysomelidae, Attelabidae and Curculionidae)

C-banding patterns of 32 beetle species from the families Elateridae, Cantharidae, Oedemeridae, Cerambycidae, Anthicidae, Chrysomelidae, Attelabidae and Curculionidae were studied using the C-banding technique. Mitotic and meiotic chromosomes were previously described for 14 species. From among 18 species that had never been cytogenetically studied, we determined the diploid and haploid chromosome numbers and the sex determination system for 12 beetles. The karyotype for 6 species is not described because of a lack of mitotic and meiotic metaphases. Results confirm that most of the beetle species possess a small amount of heterochromatin and C-positive segments are weakly visible in pachytene stages and weakly or imperceptible in mitotic and meiotic metaphases. In some species with a large amount of heterochromatin, C-bands were observed in the centromeric region in all autosomes and the X chromosome. The Y chromosome does not show C-bands with the exception of Oedemera viridis in which it possesses a small band of heterochromatin.     

醉鱼草属四个种的核型分析

报道了醉鱼草属（Btuldleja）4个种的染色体核型。云南醉鱼草（B.yunnanensis）的核型公式为2n=2x=38=22m＋16sm,皱叶醉鱼草（B．crispa）为2n=2x=38=26m＋10sm＋2st,密蒙花（B．officinalis）为2n=2x=38=20m＋16sm＋2st,口本醉鱼草（B．japonica）为2n=2x=38=20m＋16sm＋2st。日本醉鱼草的核型为2B型,其它3个种的核型为2A型。根据核型分析结果,结合形态学特征和已有的细胞学资料,初步讨论了醉鱼草组（Sect．Neemda）两个系（Series）可能的演化关系。     

Karyotype of Four Species in Buddleja ( Loganiaceae) *

The chromosome numbers and karyotypes of the 4 species in genus Buddleja were reported. The karyotype formulas are 2n= 2x= 38= 22m+ 16sm ( B1 yunnanensis) , 2n= 2x= 38= 26m+ 10sm+ 2st ( B1 crispa) , 2n= 2x= 38= 20m+ 16sm + 2st ( B1 off icinalis ) , and 2n= 2x= 38= 20m+ 16sm+ 2st ( B1japonica) . Karyotype of B1japonica belongs to Stebbins. s 2B type and other 3 species belong to Stebbins. s 2A type. Based on the cytological data ( karyotypes and the recorded chromosome numbers) and the species morphologies, the evolution trend of the two series in Sect1Neemda was briefly discussed.     

Cytogenetic characterization and description of an XX/XY1Y2 sex chromosome system in catfish Harttia carvalhoi (Siluriformes, Loricariidae)

Karyotypic and cytogenetic characteristics of catfish Harttia carvalhoi (Paraíba do Sul River basin, S?o Paulo State, Brazil) were investigated using differential staining techniques (C-banding, Ag-staining) and fluorescent in situ hybridization (FISH) with 18S and 5S rDNA probes. The diploid chromosome number of females was 2n = 52 and their karyotype was composed of nine pairs of metacentric, nine pairs of submetacentric, four pairs of subtelocentric and four pairs of acrocentric chromosomes. The diploid chromosome number of males was invariably 2n = 53 and their karyotype consisted of one large unpaired metacentric, eight pairs of metacentric, nine pairs of submetacentric, four pairs of subtelocentric, four pairs of acrocentric plus two middle-sized acrocentric chromosomes. The differences between female and male karyotypes indicated the presence of a sex chromosome system of XX/XY1Y2 type, where the X is the largest metacentric and Y1 and Y2 are the two additional middle-sized acrocentric chromosomes of the male karyotype. The major rDNA sites as revealed by FISH with an 18S rDNA probe were located in the pericentromeric region of the largest pair of acrocentric chromosomes. FISH with a 5S rDNA probe revealed two sites: an interstitial site located in the largest pair of acrocentric chromosomes, and a pericentromeric site in a smaller metacentric pair of chromosomes. Translocations or centric fusions in the ancestral 2n = 54 karyotype is hypothesized for the origin of such multiple sex chromosome systems where females are fixed translocation homozygotes whereas males are fixed translocation heterozygotes. The available cytogenetic data for representatives of the genus Harttia examined so far indicate large kayotype diversity.     

Chromosomal diversity and evolution in the ground beetle genus Bembidion and related taxa (Coleoptera: Carabidae: Trechitae)

Chromosome numbers and sex chromosome systems of 154 previously unstudied Bembidion species are described. The genus is nearly uniform: males of 176 of 205 species are 2n=22+XY. Karyotypes are presented for 30 species. There is some variation among species in size of Y and size of autosomes. Within most species autosomes are subequal in size, and metacentric or submetacentric. Subterminal secondary constrictions and B chromosomes are reported from several species.The supertribe Trechitae (Zolini + Trechini + Pogonini + Bembidiini) is hypothesized to be primitively male 2n=22+X or 24+X, and the ancestral Bembidion stock 2n=22+XY. Conclusions are based on the most parsimonious hypothesis of ancestral state given an inferred phylogeny of the group, rather than the widespread-is-primitive arguments used previously. Evolution within Bembidion away from the presumably-primitive 2n=22+XY is discussed. Six lineages have lost Y chromosomes; seven have undergone changes in autosome number. It is not known why such changes are so scarce, nor what particular rearrangements led to the observed diversity. Nonetheless, the cytogenetic data can be used to infer a monophyletic origin of groups possessing derived chromosome numbers or sex chromosomes, and to help resolve species limits.     

中国两种掌突蟾(锄足蟾科Pelobatidae,无尾目Anura)的细胞遗传学研究

本文对分布于云南境内的两种Leptolalax——L.ventripunctatus和L.alpinus的常规Giemsa核型、C-带和Ag-NORs作了研究,结果表明L.ventripunctatus的2n=22,20M 2T,NF=42,1对Ag-NORs位于5(?),并呈现异形现象,该区域亦显C-带正染;L.alpinus 2n=24,14M 4SM 6T,NF=42,1对Ag-NORs位于No.8短臂端部,并有随体联合现象。两种的着丝点区域均呈现C-带正染。     

Sex chromosome differentiation in Belostoma (Insecta: Heteroptera: Belostomatidae)

Belostoma, a genus of the family Belostomatidae, includes species of great ecological importance as biocontrol agents. Few species of these species have been the subject of cytogenetic analyses. Karyotypic evolution in this genus involves agmatoploidy and simploidy; there are also different sex chromosome systems. We examined two Belostoma species (B. dilatatum and B. candidulum) collected from the Paranapanema River Basin (Brazil). Mitotic and meiotic analysis revealed 2n(♂) = 26 + X(1)X(2)X(3)Y for B. dilatatum and 2n(♂) = 14 + XY for B. candidulum; both karyotypes have holokinetic chromosomes. Differences in heterochromatin distribution were also observed between the species, besides variation in the localization of CMA(3)(+)/DAPI(-) blocks. The existence of different types of sex chromosome systems in these species was confirmed based on arrangements of the chromosomes in different meiotic stages. We identified a new sex system in B. dilatatum, and make the first cytogenetic report on B. candidulum.