Cytogenetics of bisexual/unisexual species of Poecilia. I. C-bands, Ag-NOR polymorphisms, and sex chromosomes in three populations of Poecilia latipinna

Three populations of the North American cyprinodont fish Poecilia latipinna, considered to be one of the progenitor species of the gynogenetic unisexual P. formosa, were analyzed by C-banding and Ag-staining. C-bands were found to be polymorphic, and Ag-staining showed a high degree of variability in both the number and location of nucleolus organizer regions. The C-banding and Ag-staining patterns allow, to a certain extent, to distinguish individual specimens from each of these populations. Females of the three populations were found to have a heteromorphic chromosome pair, which was frequently identifiable with Giemsa staining and always after C-banding. This pair could be interpreted as sex chromosomes of the ZW/ZZ type.     

Frequency of acrocentric chromosomal associations and their silver staining in human lymphocytes in immune reactions

Ag-staining of the nucleolar organizer regions of acrocentric chromosomes of T-lymphocytes did not change during the immune response in children with porotitis and in those being in contact with parotitis-suffering children, as well as in young adults previously immunized by staphylococcal anatoxin. This character displayed individual peculiarities. No differences in these age groups were detected. A positive correlation was found between the size of Ag-band and the ability of chromosomes to make associations. Ag-staining and participation of G-chromosomes in associations was higher than those markers in D-chromosomes.     

丁酸钠对人胃腺癌MGC-803细胞核仁纤维中心和银染蛋白的影响

用透射电镜观察到MGC-803细胞的核仁是网织型的,在网眼内分布有电子密度低的纤维中心。MGC-803细胞经丁酸钠作用后,其核仁的类型发生了改变,多呈环型的,核仁的中央有一个大的纤维中心;纤维中心和银染颗粒的大小和数目明显减低;用图像分析仪测得核仁银染蛋白所占面积与核总面积的比值也明显降低。结果提示:丁酸钠可能通过抑制rRNA合成和rDNA转录活性调控MGC-803细胞的增殖。     

Ag-staining of nucleolus organizer regions on human prematurely condensed chromosomes from cells with different ribosomal RNA gene activity

The Ag-staining of the nucleolus organizer regions (NORs) of prematurely condensed chromosomes (PCCs) of human cells showing different degrees of rRNA-gene activity clearly indicates a close correlation between the positive Ag-staining of NORs and the activity of rRNA genes. The Ag-stain, however, seems insensitive to low rates of rRNA synthesis and obviously follows a threshold reaction. Furthermore it was found that the frequency of Ag-positive chromosomes involved in satellite associations in interphase does not differ from that in metaphase.     

Population polymorphism of silver-stained nucleolar organizer chromosome regions in man

Activity of nucleolar organizer regions (NORs) of acrocentric chromosomes determined by Ag-staining was comparatively studied in 40 individuals of Bulgarian and 40 individuals of Russian populations. Chromosome 21 was found to be significantly more often stained in both populations. The other NORs did not differ significantly in staining from the means. No differences were noted between individual NORs, in respect of the intensity of Ag-staining in both populations, except chromosome 15 which showed markedly decreased staining capacity in Russians. The data obtained are compared with those published in literature concerning four other populations.     

Satellite association frequency and number of nucleoli depend on cell cycle duration and NOR-activity

Summary In human lymphocyte cultures the frequencies of satellite associations in first, second, and third mitoses were investigated using the BUDR-method. A marked decrease of the association frequency with increasing numbers of cell cycles was found. The number of nucleoli seen in interphase is correlated with the satellite association frequency in the respective metaphase. Satellite association is positively correlated to Ag-staining intensity of the NORs. Individual differences in satellite associations are due to differences in NOR activity and in lymphocyte activation. BUDR diminishes somewhat the Ag-staining intensity of the NORs but has no effect on satellite association frequencies. The main reason for the decrease of satellite association frequency in second and third lymphocyte mitoses is presumably a certain dislocation of the original chromosome position during mitosis and a decreased possibility of association during the short interphases. The high association frequency in first mitosis resembles the chromosome position in the long interphase of G₀-lymphocytes.     

Frequency analyses of active NORs in nuclei of artificially induced triploid fishes

Summary The correspondence between increased numbers of both chromosomal and nuclear NORs and artificially induced triploidy in three fish species (rainbow trout, Oncorhynchus mykiss; common carp, Cyprinus carpio; and tench, Tinea tinea) has been confirmed by CMA₃ fluorescence and Ag-staining. The frequencies of cell nuclei with one, two and three active NORs, as revealed by Ag-staining, has been analyzed statistically to find the minimum cell number which verifies the increased ploidy level. A minimum sample size of about 80 cells exhibiting three active NORs is sufficient to confirm triploidy in all three species and may be of use for categorising other ploidy-manipulated fish species.     

Studies on the Silver-Staining of Plant Chromosomes

In the rye, barley and wheat, besides the Ag-NORs, some other Ag-stained regions including the telomeres, the centromeres and the middle of arms have been found. The phenomenon that the rye and barley have their own Ag-staining pattern is first described in this paper.     

The correlation between silver-staining and DAPI-induced chromosome undercondensation

The silver-staining pattern of Chinese hamster chromosomes that show DAPI-induced undercondensed areas was studied. The Ag-staining was preceded or not by dehistonizing treatments. In both cases silver preferentially precipitates on undercondensed areas. It is suggested that this phenomenon could be compared to the silver-stainability of the active NORs during mitosis when they remain undercondensed. The possible chemical nature of the protein groups responsible for the silver-staining is discussed.     

甘肃紫斑牡丹品种与中原牡丹品种银带和Giemsa C带的研究

分别对甘肃紫斑牡丹品种和中原牡丹品种进行了核型,Ａｇｇｋｐｈｔ Ｇｉｅｎｓａ Ｃ带的研究。发现紫斑牡丹品种核型组成为２ ＝１０＝８ｍ＋２ｓｔ;中原牡丹品种核型组成为２ｎ＝１０＝６ｍ＋２ｓｍ＋２ｓｔ。ＧｉｅｍｓａＣ带带型显示,供试品种均能显示染色体端带,但天染色体端带的数目及分布位置上具品种特异性。     

Sialoglycoproteins with a high amount of O-glycosidically linked carbohydrate moieties stain yellow with silver in sodium dodecyl sulfate-polyacrylamide gels

Several sialoglycoproteins and human salivary proteins were analyzed in sodium dodecyl sulfate-polyacrylamide gels using the silver/Coomassie-staining protocol (J. K. Dzandu, M. E. Deh, D. L. Barratt, and G. E. Wise, 1984, Proc. Natl. Acad. Sci. USA 81, 1733-1737) to determine the extent to which yellow Ag staining originally reported for human red blood cell glycophorins can be applied to other sialoglycoproteins. Results showed that not all sialoglycoproteins elicit a positive yellow color in the silver stain reaction. Some of the sialoglycoproteins stained as brown or negative images in the Ag-staining cycle. Alkaline beta elimination of O-glycosidically linked carbohydrate chains of glycophorin resulted in the loss of yellow color development in the Ag-staining protocol. Analysis of acidic salivary proteins showed several yellow Ag-stained bands at Mr X 10(-3) = 150, 82, 70, 51, 46, and 42. These results suggest that the carbohydrate moieties of glycophorin removable by alkaline beta elimination are responsible for the characteristic yellow color in the Ag stain reaction. In addition, under our staining conditions sialoglycoproteins with a high amount of O-glycosidically linked carbohydrate chains give a characteristic yellow silver stain.     

Molecular and cytogenetic approach to the mapping of methylated polymorphic restriction fragments of human rRNA genes

Combined restriction with Bam H I and Sal I (or Hpa II) has revealed Bam H I fragment on a non-transcribed spacer of rRNA genes in one out of four individuals under study. Using Ag-staining and hybridization in situ, chromosome 13p+ enriched by inactive rRNA gene copies was found in the given individual. Since Sal I does not restrict methylated sequences and rRNA genes are repressed by methylation, it is concluded that methylated Banm I-restricted rRNA gene fragments of non-transcribed spacer are localized in chromosome 13p+ of the individual in question.     

Variability of the nucleolar organizer activity in human lymphocytes via Ag-staining

Summary Chromosomes with Ag staining that varies from one metaphase to the other can be distinguished from those with an Ag-staining that is the same in all metaphases. The intercellular variation of an Ag-NOR can be attributed to many different factors. Whatever the importance of technical factors, they do not seem to account for the large variations in Ag-staining which were observed for each ac. This suggests the existence of a natural intercellular variability of the NOR's activity. The variation of the Ag-stainability of a given NOR, the diversity of Ag-stainings observed on the ten ac of one individual and the differences that exist between individuals raise the question of the existence of a compensation of activity between nucleolar organizers. The study, for each individual, of the mean sum of staining per metaphase reveals that this value is not absolutely constant from one individual to another; in the carriers of Robertsonian fusions it is smaller than in chromosomally normal individuals. The analysis of the transmission shows that inactive NORs remain inactive and that active NORs present a variation in the activity from one generation to the next.     

Comparison of silver staining of nucleolus organizer regions in human lymphocytes and fibroblasts

Summary Ag-staining of the nucleolus organizer region (NOR) was studied in the acrocentric chromosomes identified by Q-banding in repeated lymphocyte and skin fibroblast cultures from three different individuals. A similar pattern of Ag-stainability of NORs was found in the two tissues in each individual. Small differences concerning, in each case, only one of the acrocentric chromosomes were found between repeated lymphocyte cultures, as well as between lymphocyte and fibroblast cultures of the same individual without indication of any prevalence of one tissue type in a certain direction. The possibility that these differences are caused by different stages of NOR activation is discussed.     

Expression of ribosomal genes under the action of 5-azacytidine in the African green monkey RAMT cell line

The use of cytosine analogue--5-Azacytidine(5AzaC), derepression of ribosomal genes has been studied in one of organising chromosomes in the African green monkey RAMT cell line in which the nucleolar organizer region (NOR) in parental cells was active. The effect of 5AzaC on the functional state of NOR was assessed by the length of the secondary constriction in this chromosome and by the intensity of Ag-staining of NOR. 5AzaC was added to the cell culture at concentrations 2-16 M, either immediately after the cell passage or at the 24th h from the beginning of cell cultivation for the following 17-34 hours. As a control the cells cultivated in the absence of 5AzaC were used. Comparison of control cells with those treated with 5AzaC showed: 1) increase of the length of the second constriction in the chromosome with the initial inactive NOR in the 5AzaC--treated cells; 2) a marked increase of the intensity of NOR's Ag-staining in the same chromosome after incorporation of 5-AzaC into DNA. The conclusion about the methylation of cytosine bases in the DNA of ribosomal genes in one NOR organising chromosomes in RAMT cell line was made.     

Constitutive heterochromatin, 5S and 18S rDNA genes in Apareiodon sp. (Characiformes, Parodontidae) with a ZZ/ZW sex chromosome system

Karyotype, sex chromosome system and cytogenetics characteristics of an unidentified species of the genus Apareiodon originating from Piquiri River (Paraná State, Brazil) were investigated using differential staining techniques (C-banding and Ag-staining) and fluorescent in situ hybridization (FISH) with 5S and 18S rDNA probes. The diploid chromosome number was 2n = 54 with 25 pairs of meta- (m) to submetacentric (sm) and 2 pairs of subtelocentric (st) chromosomes. The major ribosomal rDNA sites as revealed by Ag-staining and FISH with 18S rDNA probe were found in distal region of longer arm of st chromosome pair 26, while minor 5S sites were observed in the interstitial sites on chromosome pairs 2 (smaller cluster) and 7 (larger one). The C-positive heterochromatin had pericentromeric and telomeric distribution. The heteromorphic sex chromosome system consisted of male ZZ (pair 21) and female middle-sized m/st Z/W chromosomes. The pericentric inversion of heterochromatinized short arm of ancestral Z followed by multiplication of heterochromatin segments is hypothesized for origin of W chromosome. The observed karyotype and chromosomal markers corresponded to those found in other species of the genus.     

Partial trisomy 17q

Summary A 15-year-old deeply mentally retarded male is described with partial distal 17q trisomy (17q2217qter), as the result of a de novo 17q/21p translocation. Differential Ag-staining showed that the satellites of chromosome 21 were included in the translocation chromosome.