Karyological study of some Corvine birds (Corvidae, aves)

Karyotypes were studied in the hooded and carrion crows, their naturally occurred hybrids, the jungle crow, the azure-winged magpie (2n = 80 in all aforementioned birds), and the magpie (2n = 82). Corvine birds of Primorskii Krai were karyotyped for the first time. In addition to the similarity in the diploid chromosome sets, corvine birds were shown to have a similar structure of karyotype: in all studied birds, 14 macrochromosomes (Mchs) classified into three groups according to their size were detected. By karyotype structure, birds belonging to the same genus are similar. Some intergeneric differences are due to a change in the position of centromeres of the largest and sex chromosomes. Karyotypes of interspecific hybrids of crows are remarkable for the presence of heteromorphic (t/st) chromosome pair 2 in some individuals, which apparently does not affect their fecundity. Using differential C-banding, the sex chromosome W in female magpies was identified. In addition, heteromorphism was detected in C-bands of homologs of Mch pair 4 in the hooded crow. In the jungle crow, the azure-winged magpie, and the magpie, bright QH-bands and numerous G-bands were detected on Mchs and on some microchromosomes only. Active Ag-NOR-bands were detected on one macrochromosome pair in the magpie. In all, the karyotype structure of corvine birds is comparable to the basic structural scheme of the karyotype in the order Passeriformes, which confirms the concept of conservatism of the avian karyotype.     

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.     

A karyological study of the genus Pnigalio Schrank (Hymenoptera: Eulophidae): assessing the taxonomic utility of chromosomes at the species level

We provide a karyological study of 12 species of the genus Pnigalio in an attempt to evaluate the taxonomic utility of karyotypes at the species level. For all species of Pnigalio examined the number of chromosome was 2n=12. Karyotype formulae presented mainly metacentric and submetacentric chromosomes, although a pair of acrocentrics or subtelocentrics, shorter than biarmed chromosomes, was present in some species. The analysis of karyotypes of Pnigalio showed frequent but not general interspecific variability of the chromosome traits. Although most of the studied species revealed concordance between morphological and karyological characters (centromeric index and relative length), two other categories have been identified: morphologically distinct species without reciprocal differences in karyotype structure, and morphologically similar species that strongly differ in chromosomal characters.     

Taxonomic studies ofAsarum sensu lato

The karyotype and the C-banding pattern in two species ofHexastylis andAsarum epigynum were analysed in detail, and the results obtained were compared with those of the other species ofAsarum, Asiasarum andHeterotropa previously reported. The present results were partially different from the previous reports related to the karyotypes of these species. The karyotype observed in two species ofHexastylis (2n=26) was represented by ten pairs of metacentric chromosomes and three pairs of small subtelocentric chromosomes, which is very similar to that ofAsiasarum in eastern Asia. The C-banding patterns ofHexastylis andAsiasarum, however, were clearly different from each other. A striking difference was found in one of the three pairs of small subtelocentric chromosomes. A Formosan speciesAsarum epigynum had the somatic chromosome number 2n=12 and a highly asymmetrical karyotype composed of mainly subtelocentric chromosomes. These karyological features were remarkably different from those of the other groups inAsarum s.l.     

Chromosome number and karyotype of Donax trunculus L. (Mollusca,Bivalvia, Tellinacea)

A chromosome study of Donax trunculus was made with specimens collected from a population of the French Atlantic coast. The karyotype, not previously described, consists of 19 pairs of chromosomes (2n=38) as in the majority of the species so far investigated in the Veneroida. There was no evidence of morphologically identifiable heterosomes. The karyotype is characterized by (1) a high total chromosome length which reaches 228.56 m, (2) a great heterogeneity of the chromosome length, and (3) a high number of meta- and submetacentrics, 9 and 7 pairs respectively vs. 3 pairs of subtelocentrics, giving a fundamental number of 70. Comparison with two other closely related families having reported karyological data-Scrobiculariidae and Semelidae-suggests that, although chromosome numbers are identical, the karyotype is clearly different from one family to the other.     

A cytogenetic study on three Chilean species of Chrysomelinae (Coleoptera, Chrysomelidae)

Three species of Chilean leaf beetles were chromosomally analyzed. The endemic Araucanomela wellingtonensis displays a male meioformula of 13 + Xyp with 2n = 28 chromosomes and an asymmetric karyotype with two large autosome pairs and 12 medium/small pairs of autosomes and sex-chromosomes, a diploid number which had not been found among the other species of the subtribe Paropsina sensu lato studied to date. Strichosa eburata presents a meioformula of 11 + Xyp, 2n = 24 chromosomes, as occurs in many species of chrysomelines belonging to different subtribes. Furthermore, Phaedon cyanopterum has a 16 + Xyp meioformula, that is 2n = 34 chromosomes, of small size mostly, also in agreement with the karyological findings obtained in all the other congeneric species so far examined. These cytogenetic data are discussed with respect to the previous ones in this subfamily and with other characters of taxonomic and evolutionary value.     

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.     

A Karyological Study of Some Corvine Birds (Corvidae, Aves)

Karyotypes were studied in the hooded and carrion crows, their naturally occurred hybrids, the jungle crow, the azure-winged magpie (2n= 80 in all aforementioned birds), and the magpie (2n= 82). Corvine birds of Primorskii Krai were karyotyped for the first time. In addition to the similarity in the diploid chromosome sets, corvine birds were shown to have a similar structure of karyotype: in all studied birds, 14 macrochromosomes (Mchs) classified into three groups according to their size were detected. By karyotype structure, birds belonging to the same genus are similar. Some intergeneric differences are due to a change in the position of centromeres of the largest and sex chromosomes. Karyotypes of interspecific hybrids of crows are remarkable for the presence of heteromorphic (t/st) chromosome pair 2 in some individuals, which apparently does not affect their fecundity. Using differential C-banding, the sex chromosome W in female magpies was identified. In addition, heteromorphism was detected in C-bands of homologs of Mch pair 4 in the hooded crow. In the jungle crow, the azure-winged magpie, and the magpie, bright QH-bands and numerous G-bands were detected on Mchs and on some microchromosomes only. Active Ag-NOR-bands were detected on one macrochromosome pair in the magpie. In all, the karyotype structure of corvine birds is comparable to the basic structural scheme of the karyotype in the order Passeriformes, which confirms the concept of conservatism of the avian karyotype.     

Molecular and cytogenetic analysis of the telomeric (TTAGGG)n repetitive sequences in the Nile tilapia,Oreochromis niloticus (Teleostei: Cichlidae)

The majority of chromosomes in Oreochromis niloticus, as with most fish karyotyped to date, cannot be individually identified owing to their small size. As a first step in establishing a physical map for this important aquaculture species of tilapia we have analyzed the location of the vertebrate telomeric repeat sequence, (TTAGGG)n, in O. niloticus. Southern blot hybridization analysis and a Bal31 sensitivity assay confirm that the vertebrate telomeric repeat is indeed present at O. niloticus chromosomal ends with repeat tracts extending for 4-10 kb on chromosomal ends in erythrocytes. Fluorescent in situ hybridization revealed that (TTAGGG)n is found not only at telomeres, but also at two interstitial loci on chromosome 1. These data support the hypothesis that chromosome 1, which is significantly larger than all the other chromosomes in the karyotype, was produced by the fusion of three chromosomes and explain the overall reduction of chromosomal number from the ancestral teleost karyotype of 2n=48 to 2n=44 observed in tilapia.     

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.     

四种天牛的核型比较研究

为弄清天牛的核型特征, 补充我国天牛染色体分类特征和天牛细胞分类学的基础研究空缺, 本文以4种沟胫天牛亚科天牛为研究对象, 选取天牛的分裂旺盛组织精巢（卵巢）和中肠, 在不同的条件下进行天牛染色体玻片的制备和观察。结果显示： 4种天牛染色体数目均为 2n = 20, 性别决定机制为Xy_p。其中, 云斑白条天牛Batocera lineolata的核型公式： 4L+5M+Xy_p, 大型染色体4对, 中型染色体5对, 性染色体为小型; 榉白背粉天牛Olenecamptus cretaceus marginatus、 中华八星粉天牛Olenecamptus octopustulatus chinensis（粉天牛属）和桑天牛Apriona germari的核型公式均为： 5L+4M+Xy_p, 大型染色体5对, 中型染色体4对, 性染色体为中型。粉天牛属的榉白背粉天牛和中华八星粉天牛的核型指数非常相近; 桑天牛的染色体公式虽然与粉天牛属相同, 但长度和着丝粒位置明显不同。     

Origin and evolution of avian microchromosomes

The origin of avian microchromosomes has long been the subject of much speculation and debate. Microchromosomes are a universal characteristic of all avian species and many reptilian karyotypes. The typical avian karyotype contains about 40 pairs of chromosomes and usually 30 pairs of small to tiny microchromosomes. This characteristic karyotype probably evolved 100-250 million years ago. Once the microchromosomes were thought to be a non-essential component of the avian genome. Recent work has shown that even though these chromosomes represent only 25% of the genome; they encode 50% of the genes. Contrary to popular belief, microchromosomes are present in a wide range of vertebrate classes, spanning 400-450 million years of evolutionary history. In this paper, comparative gene mapping between the genomes of chicken, human, mouse and zebrafish, has been used to investigate the origin and evolution of avian microchromosomes during this period. This analysis reveals evidence for four ancient syntenies conserved in fish, birds and mammals for over 400 million years. More than half, if not all, microchromosomes may represent ancestral syntenies and at least ten avian microchromosomes are the product of chromosome fission. Birds have one of the smallest genomes of any terrestrial vertebrate. This is likely to be the product of an evolutionary process that minimizes the DNA content (mostly through the number of repeats) and maximizes the recombination rate of microchromosomes. Through this process the properties (GC content, DNA and repeat content, gene density and recombination rate) of microchromosomes and macrochromosomes have diverged to create distinct chromosome types. An ancestral genome for birds likely had a small genome, low in repeats and a karyotype with microchromosomes. A "Fission-Fusion Model" of microchromosome evolution based on chromosome rearrangement and minimization of repeat content is discussed.     

Karyotaxonomical analysis in the genusAngelica (Umbelliferae)

Morphometric karyotype characters were studied in 25Angelica spp. (Umbelliferae, Apioideae) and in one species of the related genusTommasinia. For three species the chromosome numbers are new. In our study the majority of the species investigated are diploids with 2n = 22, some are tetraploids with 2n = 44 (for these tetraploids also diploid cytotypes are reported in the literature). Among the diploid species,A. miqueliana has a distinct karyotype consisting of submetacentric and acrocentric chromosomes only, the remaining diploids with 2n = 22 as well as tetraploids with 2n = 44 have rather symmetrical karyotypes, consisting of metacentric and submetacentric chromosomes. The very different chromosome number 2n = 28 has been found inA. gmelinii. Its karyotype includes two distinct groups of chromosomes: 8 pairs of rather large metacentrics and submetacentrics and 6 pairs of very short and asymmetrical chromosomes. Chromosome numbers and structures appear to be useful in the taxonomy of some intrageneric taxa inAngelica.     

Chromosome number, karyotype, and taxonomic considerations on the enigmatic Sellocharis paradoxa Taubert (Leguminosae, Papilionoideae, Genisteae)

Until recently, Sellocharis paradoxa Taubert, the only species of this Genisteae genus, was known solely by the isotypes. Recent new collections in Rio Grande do Sul, southern Brazil, have enabled data on chromosome number and karyotype morphology to be obtained for the first time. S. paradoxa has 2 n  = 20 chromosomes, and a bimodal asymmetrical karyotype, composed of one pair of long ( c . 6.3 µm) metacentric, five pairs of shorter acrocentric, and four pairs of shorter telocentric chromosomes ranging from c . 3.7 to 2.7 µm. The chromosome number and karyotype morphology of S. paradoxa do not fit into the Genisteae pattern. Existing information is so far insufficient to answer evolutionary questions about its origin and phylogenetic relationships, but the uniqueness of this taxon, first indicated by its peculiar leaf arrangement, and now supported by its uncommon karyological constitution, strongly suggests that the suprageneric taxonomic position of S. paradoxa should be re-evaluated.  © 2007 The Linnean Society of London, Botanical Journal of the Linnean Society , 2007, 155 , 223–226.     

Pronounced karyological divergence of the North American congeners Sphaerium rhomboideum and S. occidentale (Bivalvia: Veneroida: Sphaeriidae)

Chromosome sets of two North American sphaeriid species, Sphaeriumrhomboideum Say, 1822 and S. occidentale Lewis, 1856, were studiedusing conventional Giemsa staining and karyometric analysis.Pronounced karyological divergence of congeners was revealed.The diploid number of 2n = 44 was reported for S. rhomboideumand this is the first record of a diploid species in the highlypolychromosomic Nearctic sphaeriid fauna. The karyotype wascharacterized by medium-sized and small chromosomes, which decreasedin size gradually from 5.77 to 1.9 µm. Biarmed chromosomeswith medially and submedially located centromeres predominated,but six pairs of subtelo-telocentric elements were also observedin the karyotype. The estimated mitotic chromosome number forS. occidentale ranges from 189 to 213, but most of the cellsexamined contained about 204–209 chromosomes. A firstattempt to karyotype a polyploid sphaeriid was made. It wasrevealed that the comparatively large and middle-sized chromosomescould be grouped in four, so the karyotype presumably evolvedthrough tetraploidization. The small chromosomes formed thelarge fraction, about 137. Due to their similar and indistinctmorphologies, it was impossible to arrange them into subgroupswith confidence. Revealed karyological characteristics are discussedwith reference to the existing phylogenetic interpretationsof the evolutionary history of the Sphaeriinae. (Received 8 November 2006; accepted 25 June 2007)     

Chromosomal characteristics and karyotype evolution of Oxyopidae spiders (Araneae, Entelegynae)

We made a cytogenetic analysis of four species of Oxyopidae and compared it with the karyotype data of all species of this family. In Hamataliwa sp, the mitotic cells showed 2n♂ = 26+X(1)X(2) and telocentric chromosomes. The 2n♂ = 28, which has been described for only one oxyopid spider, is the highest diploid number reported for this family. Peucetia species exhibited distinct karyotype characteristics, i.e., 2n♂ = 20+X(1)X(2) in P. flava and 2n♂ = 20+X in P. rubrolineata, revealing interspecific chromosome variability within this genus. However, both Peucetia species exhibited telocentric chromosomes. The most unexpected karyotype was encountered in Oxyopes salticus, which presented 2n♂ = 10+X in most individuals and a predominance of biarmed chromosomes. Additionally, one male of the sample of O. salticus was heterozygous for a centric fusion that originated the first chromosomal pair and exhibited one supernumerary chromosome in some cells. Testicular nuclei of Hamataliwa sp and O. salticus revealed NORs on autosomal pairs, after silver impregnation. The majority of Oxyopidae spiders have their karyotype differentiated by both reduction in diploid number chromosome number and change of the sex chromosome system to X type; however, certain species retain the ancestral chromosome constitution 2n = 26+X1X2. The most remarkable karyotype differentiation occurred in O. salticus studied here, which showed the lowest diploid number ever observed in Oxyopidae and the second lowest registered for Entelegynae spiders.     

The evolution of the avian genome as revealed by comparative molecular cytogenetics

Birds are characterised by feathers, flight, a small genome and a very distinctive karyotype. Despite the large numbers of chromosomes, the diploid count of 2n approximately 80 has remained remarkably constant with 63% of birds where 2n = 74-86, 24% with 2n = 66-74 and extremes of 2n = 40 and 2n = 142. Of these, the most studied is the chicken (2n = 78), and molecular cytogenetic probes generated from this species have been used to further understand the evolution of the avian genome. The ancestral karyotype is, it appears, very similar to that of the chicken, with chicken chromosomes 1, 2, 3, 4q, 5, 6, 7, 8, 9, 4p and Z representing the ancestral avian chromosomes 1-10 + Z; chromosome 4 being the most ancient. Avian evolution occurred primarily in three stages: the divergence of the group represented by extant ratites (emu, ostrich etc.) from the rest; divergence of the Galloanserae (chicken, turkey, duck, goose etc.)--the most studied group; and divergence of the 'land' and 'water' higher birds. Other than sex chromosome differentiation in the first divergence there are no specific changes associated with any of these evolutionary milestones although certain families and orders have undergone multiple fusions (and some fissions), which has reduced their chromosome number; the Falconiformes are the best described. Most changes, overall, seem to involve chromosomes 1, 2, 4, 10 and Z where the Z changes are intrachromosomal; there are also some recurring (convergent) events. Of these, the most puzzling involves chromosomes 4 and 10, which appear to have undergone multiple fissions and/or fusions throughout evolution - three possible hypotheses are presented to explain the findings. We conclude by speculating as to the reasons for the strange behaviour of these chromosomes as well as the role of telomeres and nuclear organisation in avian evolution.     

Chromosome banding in three species of <Emphasis Type="Italic">Hypsiboas</Emphasis> (Hylidae,Hylinae), with special reference to a new case of B-chromosome in anuran frogs and to the reduction of the diploid number of 2n = 24 to 2n = 22 in the genus

The chromosomes of hylids Hypsiboas albopunctatus, H. raniceps, and H. crepitans from Brazil were analyzed with standard and differential staining techniques. The former species presented 2n = 22 and 2n = 23 karyotypes, the odd diploid number is due to the presence of an extra element interpreted as B chromosome. Although morphologically very similar to the small-sized chromosomes of the A complement, the B was promptly recognized, even under standard staining, on the basis of some characteristics that are usually attributed to this particular class of chromosomes. The two other species have 2n = 24, which is the chromosome number usually found in the species of Hypsiboas karyotyped so far. This means that 2n = 22 is a deviant diploid number, resulted from a structural rearrangement, altering the chromosome number of 2n = 24 to 2n = 22. Based on new chromosome data, some possibilities were evaluated for the origin of B chromosome in Hypsiboas albopunctatus, as well as the karyotypic evolution in the genus, leading to the reduction in the diploid number of 2n = 24 to 2n = 22.     

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。     

Karyotypic studies in Solanum section Lasiocarpa (Solanaceae)

Mitotic chromosomes of 13 species included in Solanum sect. Lasiocarpa were studied. All species have 2n = 24. The chromosome numbers of S. stagnale, S. felinum, and S. repandum are reported for the first time. Statistical analyses of chromosomes, genome length, and centromere position yielded estimates of karyotype composition and asymmetry. A generalized karyotype of the section shows that most of the chromosomes are metacentric (73%) or submetacentric (25.6%). Two pairs of subtelocentric chromosomes are present only in S. sessiliflorum. Satellites are quite common, characterizing chromosomes for ten species and are attached to the short arms of either m or sm chromosomes. They could be seen in 10% to 70% of the cells. Only S. pseudolulo bears two satellited chromosomes, one of them attached to a long chromosome arm. Although the section is chromosomally quite homogeneous, species can be distinguished by karyotype formula, presence of satellites in a particular chromosome pair, and total chromosome length. There are no indications of major chromosomal rearrangements within the section. Using cytological data exclusively, cluster analysis indicates S. sessiliflorum is isolated in the section. Solanum candidum and S. vestissimum are somewhat isolated as well and have unique karyological traits. Solanum pectinatum has a peculiar karyotype, but in the phenogram it is not particularly separated. Karyotype features suggest that morphological differentiation was not always followed by chromosomal divergence. The origin of the domesticated S. quitoense is no further elucidated by our data.