Karyological characteristics of Siberian fir (<Emphasis Type="Italic">Abies sibirica</Emphasis> Ledeb.) in Central Siberia

Data are presented on the karyotype structure of the Siberian fir (Abies sibirica Ledeb.) from five populations of the Central Siberia. The chromosome set (2n = 24) contains seven pairs of metacentric (I–VII), four pairs of submetacentric (VIII and X–XII), and one pair of intercentric (IX) chromosomes. The morphometric parameters of the identified chromosome groups had close values in the studied populations. The variation coefficients of chromosomal parameters of the Siberian fir correspond to very low and low variability. The intraspecific chromosome polymorphism of the Siberian fir is connected mainly to variations in the number and peculiarities of the nucleolar organizing regions of chromosomes. In the territory with technogenic loading, a wide spectrum of genomic mutations of the mixoploidy type was observed in the seed off-spring of the Siberian fir; triploid seedlings, as well as rare cases of somatic reduction of chromosomes, were revealed.     

Sequence differentiation associated with an inversion on the neo-X chromosome of Drosophila americana

Sex chromosomes originate from pairs of autosomes that acquire controlling genes in the sex-determining cascade. Universal mechanisms apparently influence the evolution of sex chromosomes, because this chromosomal pair is characteristically heteromorphic in a broad range of organisms. To examine the pattern of initial differentiation between sex chromosomes, sequence analyses were performed on a pair of newly formed sex chromosomes in Drosophila americana. This species has neo-sex chromosomes as a result of a centromeric fusion between the X chromosome and an autosome. Sequences were analyzed from the Alcohol dehydrogenase (Adh), big brain (bib), and timeless (tim) gene regions, which represent separate positions along this pair of neo-sex chromosomes. In the northwestern range of the species, the bib and Adh regions exhibit significant sequence differentiation for neo-X chromosomes relative to neo-Y chromosomes from the same geographic region and other chromosomal populations of D. americana. Furthermore, a nucleotide site defining a common haplotype in bib is shown to be associated with a paracentric inversion [In(4)ab] on the neo-X chromosome, and this inversion suppresses recombination between neo-X and neo-Y chromosomes. These observations are consistent with the inversion acting as a recombination modifier that suppresses exchange between these neo-sex chromosomes, as predicted by models of sex chromosome evolution.     

A new chromosomal race (2n=44) of Nannospalax xanthodon from Turkey (Mammalia: Rodentia)

A new karyotype for blind mole rats was recorded in Tunceli province in Eastern Turkey. The karyotype contained 44 chromosomes, including 13 biarmed pairs, 7 acrocentric pairs, and one heteromorphic pair with a submetacentric and an acrocentric homologue in the autosomal complement (FNa=69). The X chromosome was submetacentric and the Y chromosome medium-sized subtelocentric (FN=73). Distinct dark centromeric C-bands were observed on most of the biarmed and three pairs of the acrocentric autosomes. The NORs were detected on short arms of three subtelocentric pairs and one acrocentric pair of autosomes. The diploid number of chromosomes and the karyotype characteristics observed are obviously unique among hitherto studied populations of blind mole rats and the complement can be evaluated as a new chromosome race of Nannospalax xanthodon. The distribution ranges of individual chromosome races of the species recorded in Eastern Anatolia are revised and possible interracial hybridization is discussed in respect of the finding of a new race.     

江豚的染色体核型研究

江豚(Neophocaena phocaenoides)是鲸目(Cetacea)鼠海豚科(Phocaenidae)的一种小型齿鲸,在淡水和海洋中均有分布。关于江豚染色体的研究,国外文献中尚未见记载,国内亦无报道。Pilleri和Gihr(1972,1975)根据江豚的形态解剖学的研究,认为我国产的江豚和印度洋的及日本海的江豚不属同一个种,但国际上对此尚有不同意见。因此,搞清江豚染色体的核型,将可有助于澄清江豚属的的分类问题。本文就我国长江产江豚的染色体核型作初步探讨。     

Karyotypes of Rana tagoi Okada with diploid number 28 in the Chausu Mountains of the Minamishinshu district of Nagano Prefecture, Japan (Anura: Ranidae)

Karyotypes of Tago's brown frog Rana tagoi from the Chausu mountains in Minamishinshu of Nagano Prefecture were examined by conventional Giemsa staining, C-banding and late replication (LR)-banding. Chromosome number was 2n = 28 in all cases. The 28 chromosomes consisted of four pairs (1-4) of large biarmed chromosomes, two pairs (5-6) of telocentric chromosomes and eight pairs (7-14) of small biarmed chromosomes. Chromosome pair 11 had a secondary constriction on the long arm. In females, the C-band on the long arm of chromosome pair 6 was detected in both homologs, but was absent from the arms of the homologs of chromosome pairs 5 and 9. In males, C-bands were found in the long arms of both homologs of chromosome pairs 5 and 6, were present only in one homolog of chromosome pair 5 for certain male specimens and found in only one homolog of chromosome pair 9. Specimens of R. tagoi (2n = 28) should thus have two pairs of telocentric chromosomes to provide the same number of chromosome arms, these originating quite likely from chromosome pair 1 in the 26-chromosome specimens by centric fission. Heteromorphic sex chromosomes of the XX-XY type in R. tagoi (2n = 28) in the Chausu mountains were identified. Karyotypes of tail-tip cells from a hybrid tadpole between female R. tagoi (2n = 26) from the Hinohara village in Tokyo and male R. tagoi (2n = 28) from the Chausu mountain population were examined by squash preparation. Chromosome number was 2n = 27 in all tadpoles. The 27 chromosomes consisted of one chromosome set of R. tagoi (2n = 28) and one of R. tagoi (2n = 26).     

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.     

Karyotype of Brazilian Anopheles albitarsis sensu lato (Diptera:Culicidae)

Anopheles (Nyssorhynchus) albitarsis sensu lato is an important malaria vector in Brazil, especially in the Brazilian Amazon region. Chromosome preparations of fourth-instar larvae of A. albitarsis from Iranduba and Coari (AM) and Ilha Comprida (SP) were analyzed for karyotype determination and to improve cytogenetic identification of this species. Anopheles albitarsis possesses 2n = 6 chromosomes, with two pairs (submetacentric and metacentric) of autosomes and one pair of sex chromosomes, with X-Y dimorphism. The sex pair is homomorphic and acrocentric in females and heteromorphic in males, with a punctiform Y chromosome. Somatic pairing was detected in the prometaphase and metaphase chromosomes of the three A. albitarsis populations. Apparently, sex chromosome evolution in the Culicidae does not function as does evolution in the Culicidae, since it occurs in the subfamily Anophelinae, which possesses heteromorphic sex chromosomes and is regarded as primitive, based on several criteria. These karyotype data on the albitarsis complex reinforce the hypothesis that sex chromosome evolution in the subfamily Anophelinae is conserved, and the variation revealed in the mean size of chromosomes in three populations indicates that selective pressure in these populations is occurring only at a genetic level.     

Observation on Chromosomes of Wildflowers in China

In this paper 7 species of wildflowers were collected from Beijing suburb and Jilin Province. They are all common sightly and hardy perennials in their localities (See the Appendix for detail of the materials). The micrographs of their somatic metaphases are shown in Plate 1; the karyotype formulae, ranges of chromosome length and classification of karyotypes according to Stebbins (1971) are shown in Table 1; the idiograms of 5 species in Figs. 1-5. The karyotype analysis is made on the basis of Li and Chen (1985)⁽¹⁾. The essential points are as follows; (1) Ten pairs of chromosomes of Achyrophorus ciliatus are all submetacentric (sm). (2) Twelve pairs of chromosomes are all metacentric (m), and the short arms of the seventh pair of chromosomes with a pair of satellites in Orychophragmus violaceus. (3) The seventh and nineth pairs of chromosomes are sm and the short arms of latter with satellites in Silene repens var. angustifolia. It is reported for the first time. (4) In Scabiosa tschiliensis. the first, fourth, fifth and eighth pairs of chromosomes are sm, the sixth is terminal (t). The second and seventh are subterminal (st), the third is m. There are satellites on the short arms of third and seventh pairs. It is reported for the first time. (5) The eleventh pair of chromosomes is sm and the others are all m. The short arms of the twelfth pairs with satellites in Lychnis fulgens. (6) The chromosome number (2n) is 42, with a pair of satellites in Papaver pseudo-radicatum. It is also reported for the first time. (7) The chromosome number is2n=56 with two pairs of satellites in Rehmannia glutinosa.     

Chromosome characterization and biogeographic relations among three populations of the driftwood catfish Parauchenipterus galeatus (Linnaeus, 1766) (Siluriformes: Auchenipteridae) in Brazil

The present study employed basic and molecular cytogenetic methods to characterize three populations of Parauchenipterus galeatus from the basins of the Paraná and São Francisco Rivers, and a region of connection between the two basins. Although the diploid number was equal to 58 chromosomes, variations in karyotype formula were detected among the populations. B chromosomes were detected only in the population from the São Francisco River. Heterochromatin was located in the terminal position in almost all the chromosomes and in the pericentromeric position in some acrocentric chromosomes in the three populations. A single nucleolus organizer region was detected by silver nitrate and 18S rDNA‐fluorescent in situ hybridization in the short arm of one subtelocentric pair in the three populations, varying only in the chromosome pair bearing this site. The 5S rDNA sites were located in two submetacentric chromosome pairs in the three populations, varying only in the chromosome pairs bearing these sequences. Classic and molecular chromosome markers, along with the context of the natural history of the formation of hydrographic basins, ecological aspects, and the geographic isolation of populations between hydrographic basins and within the same basin, were important contributions to the discussion on possible biogeographic relations among the populations of Parauchenipterus galeatus. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 648–656.     

Identification of the sex chromosome pair in chum salmon (Oncorhynchus keta) and pink salmon (Oncorhynchus gorbuscha)

Fluorescence in situ hybridization (FISH) using a probe to the male-specific GH-Y (growth hormone pseudogene) was used to identify the Y chromosome in the karyotypes of chum salmon (Oncorhynchus keta) and pink salmon (Oncorhynchus gorbuscha). The sex chromosome pair is a small acrocentric chromosome pair in chum salmon and the smallest metacentric chromosome pair in pink salmon. Both of these chromosome pairs are morphologically different from the sex chromosome pairs in chinook salmon (Oncorhynchus tshawytscha) and coho salmon (Oncorhynchus kisutch). The 5S rRNA genes are on multiple chromosome pairs including the sex chromosome pair in chum salmon, but at the centromeres of two autosomal metacentric pairs in pink salmon. The sex chromosome pairs and the chromosomal locations of the 5S rDNA appear to be different in all five of the North American Pacific salmon species and rainbow trout. The implications of these results for evolution of sex chromosomes in salmonids are discussed.     

Karyotype variation in Drosophila birchii

Drosophila birchii, a member of the melanogaster species group of the subgenus Sophophora, is common in the tropical rain forests of the Australia-New Guinea areas. Chromosome squashes are easily prepared from the larval ganglion cells and the sex chromosomes are readily recognizable. The species exhibits a remarkable karyotype variation. The metaphase plate figures, in general, show two pairs of V's, one pair of dots and one pair of sex chromosomes. Variations in metaphase chromosome morphology are found in the X (with four types), the Y (with three types) and chromosome IV (with two types). Chromosomal interchanges between X- and Y-chromosomes Type I are postulated to be involved in the differentiation of sex chromosome morphology while the modification of chromosome IV seems likely to be a result of the acquisition of extra heterochromatin. These chromosome types form seven distinct metaphase plate figures, all encountered in wild populations, thus giving D. birchii the most variable karyotype in the genus Drosophila.     

Quantitative studies on the arrangement of human metaphase chromosomes

Summary The spatial relationships between the homologous pairs of chromosomes in the normal human colcemid-treated metaphase plate were tested by two different mathematical approaches: (a) determination of the distances between the centromeres of the homologous chromosomes compared to the mean distance of all centromeres of the mitosis in question; (b) measuring the distances of the different chromosomes from the center of the mitosis.The following results were obtained: (1) The arrangement of human metaphase chromosomes does not follow a normal distribution; the distribution is narrower and taller, probably due to an impairment of free chromosome spreading by the cell membrane. We believe that only in membraneless mitotic cells should the chromosome-spread correspond to a normal distribution under the same preparation conditions. (2) There is a positive correlation between decreasing chromosome size and decreasing mean distance between homologous chromosomes. (3) A close positive correlation exists between increasing chromosome size and increasing distance to the barycenter of the mitosis. (4) There is also a close positive correlation between the distance of homologous chromosome pairs and their distance from the center of the mitosis, i.e., with increasing distance from the center of the mitosis, the distance between the homologous partners increases. (5) The following statistically significant deviations from these rules could be established: (a) The large acrocentric chromosomes are closer associated, as one would expect from their size, probably due to their participation in the nucleolus organization; (b) in the female cell one of the two X chromosomes has an extremely peripheral localization; the X chromosomes are furthest apart of all pairs of homologous chromosomes; (c) the chromosome pairs 6 and 8 are relatively close together in spite of their peripheral position, suggesting a truc close association of the homologus partners; (d) the chromosome pair 18 has a more peripheral position than expected, and a relatively large mean distance between the homologous partners; (e) the chromosome pair 1 has a much more central position and a closer association than is expected from its size.     

Unusual chromosome pairing and B chromosomes inBriza spicata (Poaceae)

One plant from a population ofBriza spicata (Poaceae) was found to have highly irregular meiotic behaviour. It is characterized by having a reduced chiasma frequency, a large between cell variance in chiasma frequency and the formation of multivalents involving pairs of A chromosomes. The B chromosome present in this plant also forms multivalents with a pair of A chromosomes. It is suggested that the normal control of strict bivalent pairing has broken down and homoeologous chromosomes are associating as multivalents. Furthermore, the partial homology of the B chromosome with a pair of A chromosomes is revealed.     

蝙蝠科七种蝙蝠的核型

报道了贵州7 种蝙蝠科蝙蝠的核型。伏翼和印度伏翼的染色体数为2n = 26 , 常染色体都由10 对双臂染色体和2 对微小点状染色体组成, N.F = 44 , 性染色体是大小悬殊的端着丝粒染色体; 两者核型的主要区别在于前者的No.3 是中着丝粒染色体, 后者为亚中着丝粒染色体; 大鼠耳辐(四川亚种) 、水鼠耳蝠和西南鼠耳蝠的染色体数都是2n = 44 , 常染色体都由4 对中着丝粒染色体和17 对端着丝粒染色体组成, N.F = 50 , 其中大鼠耳蝠(四川亚种) 和水鼠耳蝠核型非常相似, 西南鼠耳蝠与前二者有一定区别; 山蝠(福建亚种) 是2n = 36 , 常染色体包括7 对中着丝粒染色体、1 对亚中着丝粒染色体和9 对端着丝粒染色体, N.F = 50 ; 南蝠2n = 50 , 常染色体由24 对端着丝粒染色体组成, N.F = 48 , X染色体是最大的中着丝粒染色体。     

马尾松染色体荧光带型的研究

对马尾松有丝分裂中期染色体荧光带纹的分析结果表明,其色霉素Ａ的染色体的荧光带赤;１对为着丝粒区和臂间我均有带纹的中间着丝染色体。６对为臂间区有带纺的中间着丝粒染色体;２对为着丝粒区有带纹的中间着丝粒染色体;３对无带纹的中间或近中着丝粒染色体;１对为着丝粒区有带纹的近中着丝粒染色体。     

臭鼩染色体的研究

本文采用骨髓染色体制片法,对捕自我国浙江萧山市的臭鼩进行了组型、G-带、C-带和核仁组织区银染的观察分析。结果表明,我国臭鼩染色体数目为2n=40,组型为8(m)+2(sm)+10(st)+18(t),性染色体为,(?):X(m或sm),Y(m或sm);♀:XX(m或sm)。G-带较为丰富,每一对染色体都有其特定的带型,较易于辨别与配对。在C-带方前,4对中间着丝粒染色体与5对亚端着丝粒染色体均具有不同程度的着丝粒带,1对亚中着丝粒染色体与9对端着丝粒染色体缺乏C-带物质,性染色体具丰富的远端带及中间带.银染的结果显示,第5、12和13对染色体具银染物质。     

Strong linkage disequilibrium between the XY274 polymorphism and the pseudoautosomal boundary.

The pseudoautosomal boundary is defined by an Alu repeat element on the Y chromosome. The Alu element is found on all Y chromosomes and on no X chromosomes, establishing it as part of Y-specific sequences. Distal to the Alu element, sequences from the X and Y are strictly homologous, suggesting that the boundary is formed by an abrupt break in sequence homology. Further investigation of the function of the boundary has been undertaken by examining the population structure of an MspI restriction-site polymorphism (XY274), which is located 274 bp distal to the Alu insertion site. Southern blot and polymerase chain reaction analysis demonstrate fixation of the high allele (noncutting or AT base pair) of XY274 on the Y chromosome in most populations, while a full range of high allele frequencies is found on the X chromosomes of different populations. Two exceptions to fixation on the Y chromosome were found in African populations. The level of linkage disequilibrium suggests that the first few hundred base pairs of the pseudoautosomal region on the Y chromosome share a single common origin more recent than the origin of the species.     

Asymmetric staining of Ctenomys chromosomes after treatment with AluI restriction nuclease

After treatment with the endonuclease AluI for 6 or 24 h, chromosomes of two populations of the South American rodent Ctenomys presented an asymmetric banding pattern after Giemsa staining. These asymmetric patterns were chromosome specific (each chromosome of a pair showed different banding pattern) but constant from cell to cell and between homologous chromosomes of the populations analysed. The nature of this peculiar staining is discussed in the light of the interaction between endonucleases and DNA in chromatin of fixed chromosomes.     

白眉长臂猿(Hylobates hoolock leuconedys)的染色体研究

本文对两只雄性白眉长臂猿的染色体的C带、G带及Ag-NORs分布进行了较详细的分析,证实染色体数2n=38,并对该种的分类地位提出了一些新看法。     

Cytogenetic analysis of some Brazilian marsupials (Didelphidae: Marsupialia)

Three species of marsupials from the Amazon region (Marmosa cinerea, Caluromys lanatus, and Didelphis marsupialis) and two from the region of S?o Paulo (Didelphis marsupialis and Didelphis albiventris) were studied. The G-banding pattern of the species with 2n = 14 (M. cinerea and C. lanatus) was very similar, as well as the pattern of G-bands in the species with 22 chromosomes (Didelphis). All of the autosomes of M. cinerea and D. albiventris have centromeric C-bands and the Y chromosome is totally C-band positive. The long arm of the M. cinerea X chromosome is completely C-band positive except for a negative band close to the centromeric region. In D. albiventris the long arm of the X chromosome is C-band positive except for a negative band close to the telomeric region. In M. cinerea the silver-stained nucleolar organizer regions (Ag-NORs) are found in the acrocentric chromosomes, being located in the telomeric region of one pair and in the centromeric region of the other pair. Caluromys lanatus has centromeric Ag-NORs in one acrocentric and in one submetacentric chromosome pairs. Didelphis marsupialis has three chromosome pairs with telomeric Ag-NORs. In D. albiventris the Ag-NORs are terminal and located in both arms of one pair and in the long arm of two pairs of chromosomes.