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1.
Enzo Orlando 《Genetica》1973,44(2):244-248
The male and female diploid complements in Mytilicola are formed both by 22 chromosomes. Two different somatic metaphase figures are found: with two minute-size chromosomes and with three minute-size chromosomes. The study of meiosis has shown that the female sex is heterogametic. The chromosome complement is 10II+XX in the male and 10II+XY in the female. A bivalent formed by two different-length homologues, is to be seen in the female meiosis at pachytene; it shows, sometimes, a light positive hetero-pycnosis. 相似文献
2.
Heteromorphic sex chromosomes of lizardfish (Synodontidae): focus on the ZZ-ZW1W2 system in Trachinocephalus myops 总被引:2,自引:0,他引:2
The karyotype and DNA content of four lizardfish species (family Synodontidae), that is, Saurida elongata, Synodus ulae, Synodus hoshinonis and Trachinocephalus myops, were analyzed. The karyotype of T. myops significantly differed from that of the other three species having diploid chromosome number of 48 with mainly acrocentric chromosomes and the ZZ-ZW sex chromosome system. The chromosome number of male T. myops was 2n=26, while that of female T. myops was 2n=27. The karyotype consisted of 11 pairs of metacentrics, one pair of acrocentrics and, in addition, two large metacentrics in the male and a single large metacentric, a distinctly small subtelocentric and a microchromosome in the female. C-banding demonstrated that in the female the subtelocentric chromosome and the microchromosome were heterochromatic. The karyotype of T. myops was thought to be derived from a 48 chromosome type synodontid fish through the involvement of Robertsonian rearrangement; the rearrangement of the sex chromosomes proceeded during karyotype evolution. Among the chromosomes, the large metacentrics were determined to be neo-Z (a fusion of the original Z and an autosome), the microchromosomes the W1 (originally W), and the subtelocentric chromosomes the W2 (derived from an autosome pair). The miniaturization of W1 and W2 chromosomes and their heterochromatinization suggested that sex chromosomes in this species have been already highly differentiated. The findings on DNA content implied that the karyotype of T. myops evolved by centric fusion events without loss in DNA amount. 相似文献
3.
泰和乌骨鸡的核型与带型研究 总被引:16,自引:2,他引:16
采用外周血淋巴细胞培养--空气干燥法,对泰和乌骨鸡染色体核型和带型进行了研究。结果表明:泰和乌骨鸡体细胞染色体数目2n=78,染色体基本臂数AF=90,1、9号染色体及Z、W性染色体为中央着丝粒(m)染色体,2、4、7号染色体为亚中央着丝粒(sm)染色体,3、6、8、10号染色体为端着丝粒(t)染色体。G带研究表明:前10对大型染色体可分为29个区,190条带。C带处理发现,所有母鸡分裂相中W性染色体都出现C带并整条深染。Ag-NORs研究发现:Ag-NORs常定位于1、2号常染色体短臂和Z性染色体短臂端部;Ag-NORs数目分布范围为1~6;平均每个细胞的Ag-NORs数在雌、雄鸡中分别为2.94和2.96。
Abstract:This study made the chromosome slides of Taihe Silkies by the peripheral blood lymphocyte culture-drying method,and analyzed Taihe Silkies karyotype and band pattern.The results are as follow:The diploid chromosome number of Taihe Silkies was 2n=78,the basic number of chromosome arms was AF=90 and the sex chromosome type was ZZ(♂)/ZW(♀).According to the measured relative length,arm ratio and centromeric index,the first 10 pairs of macro-chromosomes are described as follows:No.1 ,9 and Z,W chromosomes were metacentrics,No.2,4,7 were submetacentrics,and No.3,6,8,10 were telocentrics.Studies on Taihe Silkies′ G-band showed that the first 10 pairs of macro-chromosomes can be divided into 29 zones and 190 bands.Being treated by C-banding technique,a totally dark-stained and easily indentified W-chromosome always showed up in the female metaphase configurations.Ag-NORs were located in the short arms′ telomere of No.1,2 euchromosomes and Z sexchromosome,the Ag-NORs number varied from 1-6.
-NORs 相似文献
4.
Vanessa Bueno Claudio Henrique Zawadzki Vladimir Pavan Margarido 《Reviews in Fish Biology and Fisheries》2012,22(1):241-250
Phylogenetic relationships and identification of species of the genus Hypostomus is still unclear. Considering this, cytogenetics may prove itself as an important tool in understanding the systematic of
this genus. Reviews in Hypostomus indicate that the diploid number ranges from 54 to 84 chromosomes, and the increase in diploid number has been associated
to higher percentages of subtelocentric and acrocentric chromosomes. Although there is a high number of species in the genus,
there are relatively few papers concerning Hypostomus cytogenetics, and most of the data is published as grey literature. With the aim to understand the chromosomal evolution
in the genus (correlation between diploid number x chromosomes types), H.
ancistroides and H.
topavae from the Piquiri River, Upper Paraná River basin, were cytogenetically analyzed, and the diploid number observed was 68 and
80 chromosomes, respectively. Additional data on the diploid number and chromosome formulae was compiled from papers (27 analyses)
and abstracts from grey literature (77 analyses). Our analysis shows no correlation between chromosome numbers and percentages
of subtelocentric and acrocentric chromosomes for most of the species, since there is considerable variation between these
percentages even between species with the same diploid number, indicating that the proportion of chromosome types is not always
associated to diploid numbers. 相似文献
5.
Two species of Odontocheila, O. confusa and O. nodicornis, from the Neotropical Region were studied regarding their karyotypes, localisation and activity of ribosomal genes and C-banding. The species, although belonging to the same genus, have quite distinct karyotypes. O. confusa has 10 pairs of autosomes and a single sex chromosome mechanism of the XY/XX type, thus a diploid value of 2n = 22 in males and females. One aneuploid male with a diploid number of 2n = 20 and one male with three B chromosomes were found in a total of eight males studied. O. nodicornis has 17 autosomal pairs and also a single chromosome system but of the X0/XX type, thus a diploid value of 2n = 35 in males and 2n = 36 in females. Fluorescence in situ hybridisation (FISH) revealed the presence of rDNA clusters in two autosomes in both species in mitotic and meiotic figures. Silver staining of male interphase nuclei confirmed the FISH results and showed that all rDNA genes were active. C-banding analysis revealed the presence of constitutive heterochromatin in the centromeres of all chromosomes in the two species plus two pairs in O. nodicornis with terminal positive C-bands. These results are discussed from the cytogenetic and evolutionary point of view. 相似文献
6.
Adult males and females of the seasonally breeding lizardCalotes versicolor were subjected to various social situations under semi-natural conditions to explain the role of socio-sexual factors in
gonadal recrudescence. They were grouped as: (i) males and females, (ii) males and females separated by a wire mesh, (iii)
same sex groups of males or females, (iv) castrated males with intact females and (v) ovariectomized (OvX) females with intact
males from postbreeding to breeding phase. Specimens collected from the wild during breeding season served as the control
group. Plasma sex steroid levels (testosterone in male and 17β-estradiol in female), spermatogenetic activity and vitellogenesis were the criteria to judge gonadal recrudescence. In intact
males and females that were kept together, gonadal recrudescence and plasma sex steroids levels were comparable to those in
wild-caught individuals. Gonadal recrudescence was at its least in all male and all female groups, and plasma sex steroids
were at basal levels. Association with OvX females initiated testicular recrudescence but spermatogenetic activity progressed
only up to the spermatid stage while males separated from females by wire mesh showed spermatogenetic activity for a shorter
period. Females grouped with castrated males and those separated from males by wire mesh produced vitellogenic follicles.
However, the total number and diameter of vitellogenic follicles, and plasma estradiol levels were lower than in the females
grouped with intact males. The findings indicate that association with members of the opposite sex with progressively rising
titers of sex steroids is crucial in both initiating and sustaining gonadal recrudescence in the lizard. Thus, members of
the opposite sex mutually regulate gonadal recrudescence in theC. versicolor. 相似文献
7.
Chromosomes of Heterobilharzia americana (Digenea: Schistosomatidae), with ZWA sex determination, from Louisiana 总被引:1,自引:0,他引:1
Mitotic chromosomes of Heterobilharzia americana from Louisiana are described from parasite material that was dissected from snails, air-dried on slides, and stained with conventional Giemsa and C-band methods. As in other schistosomes, the female is the heterogametic sex. This Louisiana strain, however, differs from a Texas strain and other schistosome species in that the male and female have different diploid numbers of chromosomes (male, 20; female, 19), and the strain has a ZZ male/ZWA female sex-determining mechanism. The chromosomes of the male resemble those of the Texas strain in number and morphology with the Z chromosomes being metacentric and the largest elements in the karyotype. The others form a series decreasing in size to very small number 10's. Chromosomes 2,3, and 4 are subtelocentric; 5 is subtelocentric to acrocentric and is satellited; 6 is submetacentric to subtelocentric; 7 is submetacentric; 8 is subtelocentric to submetacentric; 9 is metacentric to submetacentric; and 10 is metacentric. The female complement differs from the male of this strain in having only 1 normal chromosome 5. The other number 5 and most of the original W apparently have fused tandemly to form the WA chromosome (a "neo-W"). 相似文献
8.
Shannon E. Keating Aaron H. Griffing Stuart V. Nielsen Daniel P. Scantlebury Tony Gamble 《Journal of evolutionary biology》2020,33(9):1316-1326
Current understanding of sex chromosome evolution is largely dependent on species with highly degenerated, heteromorphic sex chromosomes, but by studying species with recently evolved or morphologically indistinct sex chromosomes we can greatly increase our understanding of sex chromosome origins, degeneration and turnover. Here, we examine sex chromosome evolution and stability in the gecko genus Aristelliger. We used RADseq to identify sex‐specific markers and show that four Aristelliger species, spanning the phylogenetic breadth of the genus, share a conserved ZZ/ZW system syntenic with avian chromosome 2. These conserved sex chromosomes contrast with many other gecko sex chromosome systems by showing a degree of stability among a group known for its dynamic sex‐determining mechanisms. Cytogenetic data from A. expectatus revealed homomorphic sex chromosomes with an accumulation of repetitive elements on the W chromosome. Taken together, the large number of female‐specific A. praesignis RAD markers and the accumulation of repetitive DNA on the A. expectatus W karyotype suggest that the Z and W chromosomes are highly differentiated despite their overall morphological similarity. We discuss this paradoxical situation and suggest that it may, in fact, be common in many animal species. 相似文献
9.
10.
In this work, the first cytogenetic data on Neotropical Collyrinae is provided, by way of their karyotypes, C-banding and ribosomal genes (rDNA) localization using fluorescence in situ hybridization (FISH). The two species analysed, Ctenostoma (Procephalus) ornatum ornatum (male) and Ctenostoma (Euctenostoma) rugosum(female) showed, respectively, a diploid number of 17 and 18 chromosomes. C. ornatum ornatum has a multiple sex chromosome system ( n=7 + X1X2Y), and mitotic and meiotic metaphase cells showed rDNA gene labelling in the smallest autosomal pair. In this species, no C-bands were obtained, while C. rugosum seems to exhibit centromeric and/or interstitial C-bands in almost all chromosomes. The observation of a multiple sex chromosome system in Ctenostomini ensured the appearance of this characteristic in the hypothetical ancestral of Collyrinae and Cicindelini. The subfamily Collyrinae is not uniform in what concerns diploid chromosome number and rDNA gene localization, because C.
ornatum ornatum possesses a lower chromosome number and autosomal rDNA genes when compared with the other Collyrinae species studied ( Neocollyris spp.). Independent events leading to the reduction in chromosome number might have taken place during the split of the Collyrinae into the tribes Ctenostomini and Collyrini. 相似文献
11.
A modified BrdU-Hoechst-Giemsa technique permitted the demonstration of easily reproducible replication patterns in the somatic chromosomes of Amphibia. These banding patterns allow for the first time a precise identification of all chromosomes and the analysis of the patterns of replication in the various stages of S-phase in Amphibia. Several possibilities for the use of this technique were demonstrated on three frog species of the family Ranidae, all differing greatly in their DNA-content. With this method, the homomorphic chromosome pair No. 4 in Rana esculenta could be identified as sex-specific chromosomes of the XX/XY-type. All male animals exhibit an extremely late replicating region in the Y-chromosome, which is lacking in the X-chromosome; in the female animals, both X-chromosomes replicate synchronously. These sex-specific chromosomes cannot be distinguished by other banding techniques. In the highly heteromorphic ZZ/ZW-sex chromosome system of Pyxicephalus adspersus a synchronous replication of the two Z-chromosomes of male animals and a very late replication of the short arm of the W-chromosome of female animals was demonstrated. These results support the assumption that there is no dosage compensation for Z-linked or X-linked genes by the sex chromosome inactivation mechanism in the sex chromosomes of Amphibia. 相似文献
12.
四种菊头蝠染色体组型分析 总被引:6,自引:0,他引:6
本文分析了皮氏菊头蝠(R. pearsoni chinensis),鲁氏菊头蝠(R.rouxi sinicus),角菊头蝠(R.cornutus pumilus)及中菊头蝠(R.affinis)的常规核型,现报道如下。 相似文献
13.
A general survey of the occurrence of morphologically differentiated sex chromosomes in the neotropical freshwater fishes is presented. The total number of 32 occurrences involving simple XX-XY and ZZ-ZW, and multiple X1X2Y, XY1Y2 and ZW1W2 sex chromosome systems is described, with comments on the aspects of sex chromosome evolution in this fish fauna. The occurrence of different sex chromosome systems in related species of the same genus, or in different populations of the same nominal species, involving male and sometimes female heterogamety, and differences in the molecular composition of sex-linked heterochromatin, are considered as indicative of the early stage of sex chromosomes evolution in fish. 相似文献
14.
尾斑瘰螈的核型和C带研究 总被引:3,自引:0,他引:3
用常规Giemsa染色和BSG技术研究了尾斑瘰螈的核型和C带。该螈的染色体数
为2n=24,包括9对中部着丝粒染色体和3对亚中部着丝粒染色体(Nos. 7、10、11);BSG显带处理后全部染色体都显示了弱的着丝粒带,同时还显示了46条近着丝粒区插入带; 其核型和C带均不同于已研究过的国内蝾螈科动物,未发现与性别有关的异形色体。 相似文献
15.
Two parrot species, Amazona amazonica and A. aestiva, submitted to cytogenetic analysis presented a diploid chromosome number of 2n=70 (20M+50m). With the C-banding pattern, the cells of female speciments showed an almost totally heterochromatic W chromosome. No chromosome differences were observed in the two species studied. 相似文献
16.
The montane grasshopper Podisma pedestris exists in Europe in two chromosomally distinct kinds of population. One has an XO/XX sex chromosome mechanism and a diploid chromosome number of 23 male, 24 female. The other has a neo-XY/neo-XX system and a diploid number of 22 in each sex. The development of the neo sex system in this instance has resulted from an X/L3 fusion which has converted the telocentric X element into a metacentric neo-X. In the neo-XY male this has led to a considerable restriction of chiasma formation in the region proximal to the centromere in the L3 arm of the neo-X. Since this kind of chromosome change must initially have involved a single individual it could only have succeeded in a small population isolate which underwent rapid expansion immediately following the fusion. Such an origin would have been considerably facilitated by either a modification in sex ratio or else some form of meiotic drive. 相似文献
17.
E. Bellafronte M. R. Vicari R. F. Artoni V. P. Margarido O. Moreira‐Filho 《Journal of fish biology》2009,75(9):2313-2325
Conventional and molecular chromosomal analyses were carried out on three populations of Apareiodon ibitiensis sampled from the hydrographic basins of the São Francisco River and Upper Paraná River (Brazil). The results reveal a conserved diploid number (2n = 54 chromosomes), a karyotype formula consisting of 50 m‐sm + 4st and a ZZ/ZW sex chromosome system that has not been previously identified for the species. C‐banding analysis with propidium iodide staining revealed centromeric and terminal bands located in the chromosomes of the specimens from the three populations and allowed the identification of heteromorphism of heterochromatin regions in the Z and W chromosomes. The number of 18S sites located through fluorescent in situ hybridization (FISH) varied between the populations of the São Francisco and Upper Paraná Rivers. The location of 5S rDNA sites proved comparable in one pair of metacentric chromosomes. Thus, the present study proposes a ZZ/ZW sex chromosome system for A. ibitiensis among the Parodontidae, and a hypothesis is presented regarding possible W chromosome differentiation stages in this species through DNA accumulation, showing geographical variations for this characteristic, possibly as a consequence of geographical reproductive isolation. 相似文献
18.
19.
The karyotype and major ribosomal sites as revealed using silver staining of Anatolian leuciscine cyprinid fish Acanthobrama marmid were studied. The diploid chromosome number was invariably 2n = 50. Karyotype consisted of eight pairs of metacentric, 13 pairs of submetacentric and four pairs of subtelocentric to acrocentric
chromosomes. The largest chromosome pair of the complement was subtelo-to acrocentric characteristically, which is a characteristic
cytotaxonomic marker for representatives of the cyprinid lineage Leuciscinae. The nucleolar organizer regions (NORs) were
detected in the telomeres of two pairs of medium sized submeta-to subtelocentric chromosomes. No heteromorphic sex chromosomes
were found. The karyotype pattern of A. marmid is nearly identical to that found in most other representatives of the Eurasian leuciscine cyprinids, while the multiple
NOR phenotype appears to be more derived as opposed to a uniform one, ubiquitous in this group. 相似文献
20.
Hernández-Quintero JD MH Reyes-Valdés DV Mendoza-Rodríguez M Gómez-Martínez R Rodríguez-Herrera 《Phyton》2015,84(1):107-112
The genus Dasylirion is a group of plants typically present in the Chihuahuan Desert, perennial, with a dioecious sexual behavior and commonly called sotoles. This genus has been little studied from the biological point of view, and the bases of its reproductive response remain unknown. In this work we studied the chromosome number and meiotic response of Dasylirion cedrosanum in the county of Saltillo, Coahuila, located at the North East of Mexico. For the preparation of mitotic chromosomes, we used a technique based on enzymatic treatment with pectolyase and cellulase, as well as staining with acetocarmin dye. For the study of meiosis, male flower buds were collected, fixed and stained for analysis with the same dye. As a result, the gametic (n = x = 19) and somatic chromosome (2n = 38) numbers of D. cedrosanum are reported for the first time, being consistent with previous findings in other Dasylirion species, which points to a constant ploidy level across the genus. Variation was observed in the morphology and size of the somatic chromosomes, with types ranging from submetacentric to subtelocentric, and sizes oscillating in a range of 4.43 µm, with an average total length of 112.38 µm for the diploid chromosome complement. This shows that the chromosome complement of D. cedrosanom would belong to a 3B classification of Stebins, with a medium variation between chromosome lengths and low chromosome asymmetry. This variation indicates the feasibility of constructing a chromosome ideotype for this species. The meiotic chromosome pairing showed a chromosome behavior consistent with a disomic inheritance characteristic of a diploid species, with prevalence of ring and chain bivalents, typically without pairing abnormalities. Bivalent configurations in all cases were symmetrical.The normal and symmetrical meiotic pairing indicates a balanced production of gametes, and suggests the absence of heteromorphic sex determination. 相似文献