Summary Chromosomal characteristics of nucleolar organizer regions/NORs and karyological analysis of the Tokay gecko (Gekko gecko) from Khon Kaen Province, northeast Thailand was studied. Gecko chromosome preparations were conducted by squash technique from bone marrow and testis. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosome with Giemsa s solution. The results showed that the number of diploid chromosomes is 2n=38, while the fundamental number (NF) is 50 in both males and females. The types of chromosomes were 2 large metacentric, 4 large submetacentric, 4 large telocentric, 6 medium telocentric, 4 small metacentric, 2 small acrocentric, and 16 small telocentric chromosomes. NORs are located at the secondary constriction to the telomere on long arm of the largest telocentric chromosome pair 4. There are no sex differences in karyotypes between males and females. We found that during metaphase I the homologous chromosomes showed synapsis, which can be defined as 19 ring bivalents and 19 haploid chromosomes (n=19) at metaphase II as a diploid species. The karyotype formula is as follows:2n (38)
Summary A first karyotype analysis and chromosomal characteristic of nucleolar organizer regions (NORs) of the common sheathfish, Micronema apogon (Bleeker 1985), from the Chao Praya, Chi, and Song karm basins (3 populations), Thailand, were studied. Kidney cell samples were taken from 10 male and 10 female fish. The mitotic chromosome preparations were conducted by taken directly from kidney, spleen and/or gill cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that diploid chromosomes number of M. apogon was 2n=64, and the fundamental numbers (NF) were 108 in both sexes. The chromosome types consist of 10 large metacentric, 12 large submetacentric, 4 large acrocentric, 2 large telocentric, 8 medium metacentric, 8 medium submetacentric, 2 medium acrocentric, 8 medium telocentric and 10 small telocentric chromosomes. No strange size chromosomes related to sex were observed. In chromosome pair 3, the region adjacent to the telomere of the short arm showed clearly observable secondary constriction/NORs. The karyotype formula for M. apogon could be deduced as:
SummaryThe first chromosomal characteristic of nucleolar organizer regions/NORs and karyological analysis of the royal knifefish (Chitala blanci) from Mekong River, northeast Thailand, were studied. Kidney cell samples were taken from one male and one female fish. The mitotic chromosome preparations were done directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of C. blanci was 2n=42, the fundamental numbers (NF) were 42 in both male and female. The types of chromosomes were 12 large telocentric and 30 medium telocentric chromosomes. The Ag-NOR banding indicated that a single pair of NORs was observed on the long arm centromeric region of medium telocentric chromosome pair 10. The karyotype formula could be deduced as:2n (diploid) 42=L t 12 +M t 30
SummaryThe first cytogenetics of the Malayan snail-eating turtle (Malayemys macrocephala) from the Chi river basin, Khon Kaen Province, Thailand, were studied. Blood samples were taken from two male and two female turtles. Standard T-lymphocyte cell culture at 26 C for 96 h was applied. The mitotic chromosomes were harvested by colchicine-hypotonic-fixation-air drying technique. Conventional staining and GTG-banding techniques were applied to stain the chromosomes with 20% Giemsa s solution. Results showed that the number of diploid chromosomes was 2n=50, while the fundamental number (NF) was 40 in both males and females. The types of macrochromosomes were 4 metacentric, 8 submetacentric, 6 acrocentric, 4 telocentric chromosomes, and 28 microchromosomes. The GTG-banding technique showed that each chromosome pairs could be clearly differentiated and the numbers of bands in the M. macrocephala was 99. There is no observation of strangely size chromosomes related to sex. The karyotype formula is as follows:
Summary Standardized karyotype and idiogram of the vermiculate spinefoot, Siganus vermiculatus (Valenciennes, 1835) from Andaman Sea, Southern Thailand were established. The mitotic chromosome preparations were prepared directly from kidney cells of two male and two female fish. The chromosomes were stained by using conventional and Ag-NOR banding techniques. Its diploid chromosome number was 2n=48 and the fundamental number (NF) was 50 in both males and females. The types of chromosomes were 2 large acrocentric, 30 large telocentric, 12 medium telocentric, and 4 small telocentric chromosomes. No strange size chromosomes related to sex were observed. The region adjacent to the telomere of the short arm of chromosome pair 1 showed clearly observable nucleolar organizer regions (NORs). The karyotype formula could be inferred as:2n (
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