共查询到20条相似文献,搜索用时 31 毫秒
1.
The DNase I sensitivity of three different chromatin regions in mouse testicular cells was analysed by in situ nick translation with biotin-dUTP combined with various counterstaining techniques. The regions were: (i) the constitutive centromeric heterochromatin, (ii) an interstitial C-band positive insertion on chromosome 1, Is(HSR1;C5)1Lub, and (iii) the chromatin containing rDNA (designated nucleolar chromatin herein). Incorporated biotin was detected either by the horseradish peroxidase reaction with diaminobenzidine (DAB) or the alkaline phosphatase reaction with fast red. The latter resulted in a water insoluble red precipitate, which was easily removable by any organic solution thus allowing the application of various counterstaining protocols. DNase I sensitivity of the three chromatin regions was screened in different cell types of the mouse testis. The interstitial Is(HSR) region was highly DNase I sensitive when it was recognizable by strong mithramycin fluorescence. The centromeric heterochromatin was DNase I resistant when it was compacted into microscopically visible chromosomal structures (mitosis, pachytene, metaphase I and II). In interphase nuclei from Sertoli cells and spermatogonia it became highly DNase I sensitive. In round spermatids it displayed medium DNase I sensitivity. Nucleolar chromatin was not labelled by in situ nick translation when silver staining demonstrated strong protein production. Sperm cells were highly DNase I sensitive from stages 11 to 15, but resistant as mature spermatozoa. 相似文献
2.
Anabas testudineus (2n = 46) had the more conserved pattern of its C-heterochromatin distributed mainly in the centromeric region, whereas Puntius sarana (2n = 50) exhibited a rather unorthodox pattern, many chromosomes showing interstitial, some telomeric and a few chromosomes showing centromeric C-band localization. Further, lateral asymmetry in distribution of heterochromatin was also noted in two pairs of chromosomes in P. sarana. The possible implications of the differential distribution noted in these two species has been discussed. 相似文献
3.
The study of chromosomes in insects is a good tool in mitotic process analysis, zoographic localization and evolution investigation. Among them, the Sciaridae offers a karyotype with a small number of chromosomes, where the heterochromatin and nucleolar organizer region, NOR, are easily analyzed in metaphase chromosomes obtained from cerebral ganglia squashes. In this work, the heterochromatic regions on Bradysia hygida mitotic chromosomes, revealed by C-banding, were identified as centromeric blocks on A and C chromosomes and as dark interstitial region in B and X chromosomes. By Ag-DAPI staining, active nucleolus organizer region, NOR, was revealed associated to the constitutive heterochromatin in the end of the C autosome chromosome. The C-band regions and the unusual ribosomal site localization are discussed. 相似文献
4.
Metaphase chromosomes prepared from colcemid-treated mouse L929 cells by non-ionic detergent lysis exhibit distinct heterochromatic centromere regions and associated kinetochores when viewed by whole mount electron microscopy. Deoxyribonuclease I treatment of these chromosomes results in the preferential digestion of the chromosomal arms leaving the centromeric heterochromatin and kinetochores apparently intact. Enrichment in centromere material after DNase I digestion was quantitated by examining the increase in 10,000xg pellets of the 1.691 g/cc satellite DNA relative to main band DNA. This satellite species has been localized at the centromeres of mouse chromosomes by in situ hybridization. From our analysis it was determined that DNase I digestion results in a five to six-fold increase in centromeric material. In contrast to the effect of DNase I, micrococcal nuclease was found to be less selective in its action. Digestion with this enzyme solubilized both chromosome arms and centromeres leaving only a small amount of chromatin and intact kinetochores. 相似文献
5.
The ZW sex chromosomes of the European eel, Anguilla anguilla, and the American eel, A. rostrata, were examined with C-band and fluorescent staining to demonstrate the C-band heterochromatin. The W as well as Z chromosomes in both species are C-band negative except for a small amount of C-band heterochromatin in the centromeric region, in contrast to the W or Y elements of most other vertebrates. No fluorescing W-associated body is evident either in interphase nuclei or in metaphase plates. The ZW chromosomes of the two species have substantially similar size, morphology, and patterns of C-band heterochromatin. Karyologic and evolutionary implications are discussed. 相似文献
6.
Sister chromatid exchange and chromosome organization based on a bromodeoxyuridine Giemsa-C-banding technique (TC-Banding) 总被引:3,自引:0,他引:3
Hoechst 33258 fluorescent staining of bromodeoxyuridine substituted chromosomes provided a high resolution technique for following the segregation of replicated chromosomal DNA (Latt, 1973). Modifications have produced the same results after Giemsa staining (Wolff and Perry, 1975). Since this does not necessarily require Hoechst (Korenberg and Freedlander, 1975), we call this bromodeoxyuridine-Giemsa banding (BG-banding). We here describe a further modification which allows one to follow the T-rich strand of the AT-rich satellite DNA of C-band heterochromatin. We call this TC-banding. This technique was used to examine metacentric marker chromosomes found in mouse L-cells that contain many interstitial blocks of centromeric-type heterochromatin in each arm plus the usual two blocks of centromeric heterochromatin. One of the advantages of this technique for such chromosomes is that it is possible to distinguish first from second cell cycle sister chromatid exchange and unambiguously detect centromeric sister chromatid exchange. We found some chromosomes to have high rates of centromeric sister chromatid exchange. After one cycle in bromodeoxyuridine we could examine the satellite polarity of the heterochromatic DNA. Since there was no change in satellite polarity in any of the heterochromatic blocks, marker chromosomes could not have been formed by paracentric inversions, inverted insertions or inverted translocations. These results allow the formulation of several rules of chromosome organization. 相似文献
7.
Chromosomes of Eigenmannia sp. (7 males and 15 females) collected from the Tietê River in Botucatu (SP, Brazil) were examined from gill, kidney and testicular cells. The diploid chromosome number in males was 2n=31 and in females, 2n=32. In both sexes the number of chromosomal arms was 40. The difference in diploid number was due to the fusion of two acrocentrics. Mitotic and meiotic studies suggested that one of the fused acrocentrics was the Y chromosome. The sex-determining mechanism in Eigenmannia sp. could therefore be XX, AA in the female and X, \-YA A in the males. One of the males presented 2n=30 chromosomes due to the occurrence of another fusion of acrocentrics. C-banding analysis of the mitotic chromosomes revealed constitutive heterochromatin in the centromeric regions of all acrocentrics. However, small metacentrics were C-band negative. The YA chromosome is C-band negative except for a small amount of heterochromatin in the centromeric region. The nucleolar organizer region as identified by Ag-staining is present in the interstitial region of chromosome pair No. 10. 相似文献
8.
9.
A method was developed for stabilizing mitotic chromosomes. Light irradiation of permeabilized cells in a low concentration of ethidium bromide made chromatin resistant to high salt concentrations and decondensing buffer. This resistance was abolished by proteinase treatment, but not by DNase or RNase treatment. In photostabilized and extracted chromosomes, chromatin appeared as thick fibers with discrete high electron density regions. These stabilized structures might correspond to the higher-level structures (chromonemata) observed in native chromatin. Moreover, the electron density was higher in the centromeric regions than the chromosome arm material. Thus, the method allows chromatin substructures (chromonemata and centromeric heterochromatin) to be stabilized inside mitotic chromosomes. 相似文献
10.
The bimodal karyotype of pig appears to contain two types of constitutive heterochromatin, reflecting different satellite DNA families: GC-rich heterochromatin located mainly in the centromeric regions of the biarmed chromosomes, and less-GC-rich heterochromatin in the centromeric regions of the one-armed chromosomes. In order to better discriminate this constitutive heterochromatin, we treated pig chromosome preparations with eight different restriction endonucleases, followed by C-banding. This technique allowed an expedited characterization of the constitutive heterochromatin and demonstrated its great heterogeneity in pig chromosomes. Our work allowed the detection and identification of twenty-two heterochromatin subclasses (twelve centromeric, four interstitial, five telomeric, and the Yq band). Moreover, several cryptic interstitial and telomeric bands were revealed. The work presented here is useful not only for fundamental studies of chromosome banding and constitutive heterochromatin, but also offers a new approach for pig clinical cytogenetics. 相似文献
11.
首次报道了中国4种蝙蝠的G-带和C-带核型。大长舌果蝠(Eonycteris spelaea)二倍染色体数目(2n)为36,常染色体臂数(FN)为56;马来假吸血蝠(Megaderma spasma)2n=38,FN=70;黑髯墓蝠(Taphozous melanopogon)2n=42,FN=64;皱唇蝠(Chaerephon plicata)2n=48,FN=54。通过C-带显示,除着丝粒异染色质外,在皱唇蝠的许多染色体臂内和马来假吸血蝠染色体的端粒处也有较多的插入异染色质,大长舌果蝠的基因组中既有臂内异染色质也有端粒异染色质。 相似文献
12.
V. G. Dev D. A. Miller R. Tantravahi R. R. Schreck T. H. Roderick B. F. Erlanger O. J. Miller 《Chromosoma》1975,53(4):335-344
Quinacrine (Q-band) and centromeric heterochromatin (C-band) patterns of metaphase chromosomes of two subspecies of Mus musculus were compared. M. m. musculus (the laboratory mouse) and M. m. molossinus (a subspecies from Southeast Asia) had similar Q-band patterns along the length of the chromosomes, but differences were observed in the centromeric region of some chromosomes. The two subspecies had very different distributions of C-band material. Antibodies to 5-methylcytosine were bound to regions of the chromosome corresponding to the C-bands in each animal. These findings support the idea that satellite DNA, which is concentrated in the C-band region, changes more quickly than bulk DNA. The interfertility of these two subspecies permits the development of a musculus strain carrying normal marker chromosomes for genetic studies. 相似文献
13.
本文对我国云南南部的白须长臂猿(H.leucogenys)染色体的G带、C带、晚复制带及Ag-NORs进行了较为详细的研究。它的2n=52,核型公式为44(M或SM)+6(A),XY(M,A)。C带表明一些染色体着丝点C带弱化;有的染色体出现插入的和端位的C带;X染色体两臂有端位C带,Y染色体是C带阳性和晚复制的。Ag-NORs的数目,雌体有4个,雄体有5个,Y染色体上具NOR。本文对白颊长臂猿与其它长臂猿间的亲缘关系、核型进化的可能途径进行了讨论。 相似文献
14.
15.
16.
两种长臂猿染色体的C带和Ag-NORs的比较研究 总被引:1,自引:0,他引:1
本文对长臂猿属(Hylobates)中白眉长臂猿(H.hoolock)2n=38和白颊长臂猿(H.leucogenys)2n=52的染色体C带和Ag-NORs进行了比较研究。结果表明,两种长臂猿的C带核型中除多数染色体有着丝点C带外,一些染色体上还出现插入C带和着丝点C带弱化或减少现象;白眉长臂猿有全异染色质臂;白颊长臂猿有较多的端位C带。白眉长臂猿有两个Ag-NORs,而白颊长臂猿的Ag-NORs雌体有4个,雄体有5个,Y染色体上有NOR.本文对长臂猿的核型进化作了讨论。 相似文献
17.
Ana Luiza de Brito Portela-Castro Horácio Ferreira Júlio Júnior Patrícia Belini Nishiyama 《Genetica》2000,110(3):277-283
The Moenkhausia sanctaefilomenae specimens showed a karyotype consisting of 2n = 50 chromosomes with 12 metacentrics, 36 submetacentrics and two subtelocentrics. In addition to the basic karyotype, all
the males specimens have cells ranging from zero to two B microchromosomes in mitotic metaphases. These chromosomes were not
observed in the female specimens. C-band analysis showed a distribution pattern of characteristic heterochromatin with interstitial
and centromeric blocks. However, the B chromosomes were faintly stained with C-banding and were not fluorescent with CMA3 staining. The meiotic studies showed the formation of bivalents in metaphase I and in pachytene under an optical microscope.
Through synaptonemal complex analysis with an electron microscope, the pachytene showed 25 bivalents completely paired and
a small bivalent corresponding to the B chromosomes. In the same preparation, one of the B chromosomes was observed in a univalent
form. On the basis of pairing behavior and morphology it is assumed that B chromosomes of M. sanctaefilomenae show homology between them and their evolutionary aspects are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
The distribution of constitutive heterochromatin and nucleolus organizer regions (NOR's) in somatic as well as in meiotic chromosomes of Bos taurus, Bos banteng, Bison bison, and their hybrids are analyzed. C-bands are present in the centromeric regions of every autosome. The X chromosome does not show a distinct C-band in the centromeric region, whereas the Y chromosome contains an appreciable amount of C-band material. In somatic metaphases, NOR's are present on the telomeric ends of five pairs of autosomes. During pachytene, five autosomal bivalents contain NOR's on their terminal ends. Meiotic preparations made from sterile bulls did not contain stages beyond the degenerating pachytene, which are C-banding, more frequently showed clustering of heterochromatin than did the pachytene stage in normal bulls. 相似文献
19.
In situ pancreatic DNaseI digestions were used as probes to study the structural organization of facultative and constitutive heterochromatin during both mitotic and meiotic divisions. Three different types of heterochromatic regions from three insect species were chosen for this study. These regions had been previously characterized by in situ treatments with restriction endonucleases (AT and GC rich DNA sequences). Progressive increase in DNaseI concentration (from 10 to 200 ng/ml) or in incubation time (from 5 to 30 min) revealed a specific pattern of sequential digestion of the constitutive heterochromatic regions, the centromeric ones (AT-rich DNA) being the most resistant to DNaseI action. The interstitial C-bands (with AT or GC-rich DNA) were more sensitive to DNaseI, and the band 4.4 from Baetica ustalata was the most resistant of the non-centromeric bands. Similar results were obtained during meiosis, but increased accessibility to DNAseI was observed compared to mitosis. DNA methylation in the non-centromeric band 4.4 of B. ustulata could be responsible for its differential digestion with respect to the remaining intercalar heterochromatin. Facultatively heterochromatic regions (X chromosomes) were found to exhibit a differential response to DNaseI attack from mitosis to meiosis. While they behaved as cuchromatin during mitosis, they were the most resistant together with centromeric heterochromatin regions, during metaphase I and II. The different responses to digestion of the X chromosome and X-derived regions between somatic and meiotic divisions are probably a consequence of the changes in the organization of this chromosome during the facultative heterochromatinization process. 相似文献
20.
小熊猫染色体异染色质的显示 总被引:4,自引:0,他引:4
以培养的小熊猫外周淋巴细胞为实验材料,结合C-显带技术及CMA3/DA/DAPI三竽荧光杂色的方法,对小熊猫的染色体组型、C-带带型及CMA3/DA/DAPI荧光带带型进行了研究,发现:(1)经C-显带技术处理,可在小熊猫染色体上呈现出一种极为独特的C-带带型。在多数染色体上可见到丰富的插入C-带及端粒C-带。而着丝区仅显示弱阳性C-带;(2)除着丝粒区外,CMA3诱导的大多数强荧光带纹与C-阳性 相似文献