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1.
Summary In the domestic pig (Sus scrofa domestica L.) nucleolar organizer regions (NOR) were detected by a combined silver-Giemsa method (Ag-G). The main sites of NORs are the secondary constrictions of chromosomes 8 and 10. Sometimes an additional NOR was observed near the centromere of 1 homologue of chromosome 11. Associations of NORs were seen only between chromosomes 10 and at a very low frequency. 相似文献
2.
Cytological evidence on the ability of the nucleolus organizing regions to assemble pre-existing nucleolar material 总被引:1,自引:0,他引:1
S Sato 《Experientia》1988,44(3):264-266
The treatment of Vicia faba root tips with 5-azacytidine caused unequal allotment of the chromosomes; after one cell cycle, a pair of daughter nuclei was produced, one of which carried the nucleolus organizing regions (NORs) and the other of which lacked them. The pre-existing nucleolar material brought into the NOR-carrying daughter nucleus by the chromosomes disappeared concurrently with the appearance of the new nucleoli, whereas in another daughter nucleus without the NOR a number of small nucleolus-like bodies became visible at random positions. These findings suggest that in addition to ribosomal RNA synthesis the NOR has another role in cells; to stimulate the pre-existing nucleolar material to assemble at the NOR itself. 相似文献
3.
Cytological evidence on the ability of the nucleolus organizing regions to assemble pre-existing nucleolar material 总被引:1,自引:0,他引:1
S. Sato 《Cellular and molecular life sciences : CMLS》1988,44(3):264-266
Summary The treatment ofVicia faba root tips with 5-azacytidine caused unequal allotment of the chromosomes; after one cell cycle, a pair of daughter nuclei was produced, one of which carried the nucleolus organizing regions (NORs) and the other of which lacked them. The pre-existing nucleolar material brought into the NOR-carrying daughter nucleus by the chromosomes disappeared concurrently with the appearance of the new nucleoli, whereas in another daughter nucleus without the NOR a number of small nucleolus-like bodies became visible at random positions. These findings suggest that in addition to ribosomal RNA synthesis the NOR has another role in cells; to stimulate the pre-existing nucleolar material to assemble at the NOR itself. 相似文献
4.
Summary Nucleolus organizer regions (NORs) of the peripheral blood lymphocytes (PBL) of 9 mammalian species were analyzed by means of a silver-staining procedure. Species-specific NOR patterns were demonstrated. The number of NOR chromosomes was positively correlated with the nucleolar coefficient, and negatively correlated with the relative frequencies of uninucleolar cells in PBL interphase.Acknowledgment. The authors thank Professor Dr E. Groll-Knapp, of the Institute of Environmental Hygiene at the University of Vienna, for statistically evaluating the data provided. 相似文献
5.
Variable positions of nucleolus organizer regions in Bovidae 总被引:1,自引:0,他引:1
Summary Silver NOR staining has been applied to cattle (Bos taurus L.), goat (Capra hircus L.) and sheep (Ovis aries L.) chromosomes. The sites of silver NORs showed variation within the family Bovidae probably due to a reciprocal translocation event. 相似文献
6.
A combination of the silver staining method with a Giemsa banding technique is described for mammalian chromosomes. This double staining simultaneously shows silver-stained NORs and a G-band pattern, and thus allows a rapid identification of the NOR-bearing chromosomes. 相似文献
7.
Summary A combination of the silver staining method with a Giemsa banding technique is described for mammalian chromosomes. This double staining simultaneously shows silver-stained NORs and a G-band pattern, and thus allows a rapid identification of the NOR-bearing chromosomes. 相似文献
8.
DNA probes containing the repeated rDNA region ofDrosophila melanogaster (coding for e.g. 28S and 18S rRNA) hybridized in situ to distinct regions of two heterologous mitotic chromosomes of the honeybee, identifying the nucleolus organizing regions (NORs). The method allows a rapid establishment of a physical map ofApis mellifera using other DNA probes ofDrosophila. This is the first report on well-defined chromosomal markers in the honeybee. 相似文献
9.
Position of the nucleolus within the nuclei of pachytene spermatocytes of Dromiciops australis and Marmosa elegans (Didelphoidea-Marsupialia). 总被引:2,自引:0,他引:2
The location of the nucleoli within the nuclei of pachytene spermatocytes, and their relation with the position of the nucleolar organizer region (NOR) was studied. It appears that a terminal NOR determines a peripheral location of the nucleolus, due to the position of the NOR over the synaptonemal complex and to the attachment of the nucleolar chromosome telomeres at the nuclear membrane. 相似文献
10.
Lurdes F. de Almeida Toledo F. Foresti S. de Almeida Toledo 《Cellular and molecular life sciences : CMLS》1981,37(9):953-954
Summary The C-banding and silver staining of the chromosomes of the knifefishApteronotus albifrons (2n=24), demonstrated the presence of constitutive heterochromatin in the centromeric region of every chromosome, except pair 4, where the entire long arm was darkly stained, the silver stain positive nucleolus organizer region (NOR) being embedded in it.The authors are grateful to Dr Sen Pathak (University of Texas System Cancer Center at Houston, Texas, USA) and Dr Yatiyo Yassuda (Universidade de São Paulo, São Paulo, Brasil) for their suggestions. This study was supported in part by grants of the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq). 相似文献
11.
T. L. Yates A. D. Stock D. J. Schmidly 《Cellular and molecular life sciences : CMLS》1976,32(10):1276-1277
Summary The C and G chromosome banding patterns and the AgAS positive sites (NOR regions) of cultured lung cells of the Eastern mole (Scalopus aquaticus) are presented. A distinctive secondary constriction is found on a pair of autosomes instead of on the X-chromosome as previously believed. The presence of a heterochromatic heteromorphism is noted and a large amount of constitutive heterochromatin is present in the karyotype. 相似文献
12.
M. Svartman E. J. Cardoso de Almeida 《Cellular and molecular life sciences : CMLS》1993,49(8):718-720
Cytogenetical data, including G-, C-bands and NORs distribution ofOxymycterus sp (2n=54; FN=64) captured in Distrito Federal, state of Goiás, Central Brazil are presented. Our results are compared to the karyotype information already available on this genus. 相似文献
13.
J. R. Gold C. T. Amemiya W. J. Karel N. Iida 《Cellular and molecular life sciences : CMLS》1988,44(1):68-70
Summary The standard karyotype, genome size (DNA content), and genomic DNA base composition and distribution of the relict paracanthopterygian fish,Aphredoderus sayanus, were investigated. Several features of theA. sayanus genome appear to be derived rather than primitive conditions. These include a large number (at least 10 pairs) of bi-armed chromosomes, a low genome size, and high DNA asymmetry. This may indicate thatA. sayanus is not a typical paracanthopterygian fish in terms of its genome structure. 相似文献
14.
Summary Variation in the number of chromosomes was found in sheep headflies, ranging from 12 to 15 chromosomes. Of these, five pairs were common among all individuals. Among 9 larvae no males were identified. 相似文献
15.
Summary Silver-staining has been used to identify the nucleolus organizer regions (NORs) in the bharal. These show homology with sheep, goat, cattle and aoudad. The association of the NORs on both telomeres of chromosome 3 results in a ring chromosome. 相似文献
16.
M. I. Rodriguez-Garcia 《Cellular and molecular life sciences : CMLS》1977,33(6):728-729
Summary Differentiated chromosome segments were observed during studies of pollen mother cells of A. cepa during the first meiotic division. Their structure is like those of the nucleolar organizing region (NOR) described in A. cepa microspores. It is suggested that these differentiated chromosome segments correspond to the secondary constrictions seen under the optical microscope. 相似文献
17.
B. Jazdowska-Zagrodzińska B. Matuszewski 《Cellular and molecular life sciences : CMLS》1978,34(6):777-778
Summary Lamellar structures in oogonial and spermatogonial cells of gall midges were found to form a complicated system of intranuclear compartments inside which all heteropycnotic chromosomes present in the germ-line cells of these insects are located. In this way, the heteropycnotic S-chromosomes are separated by the nuclear lamellae from the remaining, decondensed chromosomes (E-chromosomes) of the interphase germ-line nucleus.This investigation was supported in part under Contract DPKBN/52/76-II.1.3.10. with the Polish Academy of Sciences. 相似文献
18.
Goldman M. A. LoVerde P. T. Chrisman C. L. Franklin D. A. Matthews F. Pitchford R. J. Richards C. S. 《Cellular and molecular life sciences : CMLS》1983,39(8):911-913
Cellular and Molecular Life Sciences - A method is described for the demonstration of nucleolar organizer regions (NORs) in freshwater snails and is applied to the study of one tetraploid and... 相似文献
19.
Résumé Dans les leucoyctes en culture de 7 TenrecsCentetes ecaudatus (4 mâles et 3 femelles) provenant de la République Malgache, l'auteur a compté 38 chromosomes et constaté que les sexes ont un caryocyte distinct. C'est la première étude faite sur les chromosomes d'un représentant de la famille des Tenrecidae (Insectivores).
Skin fibroplast cells were cultured fromCentetes ecaudatus (Animal No. 2). These cells gave a count of 38 chromosomes. Using the same techniques as above, whole blood cultures of the related tenrec,Hemicentetes semispinosus G. Cuvier, were counted. Preliminary studies indicate 38 chromosomes for this speices. 相似文献
Skin fibroplast cells were cultured fromCentetes ecaudatus (Animal No. 2). These cells gave a count of 38 chromosomes. Using the same techniques as above, whole blood cultures of the related tenrec,Hemicentetes semispinosus G. Cuvier, were counted. Preliminary studies indicate 38 chromosomes for this speices. 相似文献
20.
I. C. Potter E. S. Robinson Shirley M. Walton 《Cellular and molecular life sciences : CMLS》1968,24(9):966-967
Résumé L'étude des chromosomes somatiques de la lamproie de l'hémisphère sud,Mordacia mordax (Richardson), montre que l'équipement chromosomique diploïde de cette espèce est composé de 76 chromosomes très petits. La plupart des chromosomes sont métacentrique ou bien submétacentrique. Ces chromosomes sont différents en nombre de ceux décrits pour les lamproies de l'hémisphère nord. 相似文献