No abstract

Summary This study examined for the first time the chromosomal characteristics of nucleolar organizer regions (NORs) and karyological analysis of the pink anemonefish, Amphiprion perideraion (Bleeker 1955) from the Andaman Sea, Phuket Province, Thailand. Kidney cell samples were taken from five male and five female fish. Mitotic chromosome preparations were conducted using a standard squash technique as well as taken directly from kidney cells. Metaphase spreads were performed on microscopic slides and then air-dried. Conventional and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of A. perideraion was 2n=48, and the fundamental number (NF) was 94 in both males and females. Karyotpes were present as 2 large metacentric, 18 large submetacentric, 8 large acrocentric, 10 medium metacentric, 6 medium submetacentric, 2 medium acrocentric and 2 medium telocentric chromosomes. No irregularly sized chromosomes related to sex were observed. The results indicated that the short arm of the large acrocentric chromosome pair No. 19 showed clearly observable NORs. The karyotype formula for A. perideraion is as follows:

Karyotype and nucleolar organizer regions (NORs) were studied in the longfin carp (Labiobarbus leptocheilus) from Mekong Basin of Thailand. The mitotic chromosomes were directly prepared from kidney cells from five male and five female fishes and stained by conventional staining and Ag-NOR banding. The chromosome number was 2n=50 and the fundamental number (number of the chromosome arms, NF) was 86 in both male and female fishes. The karyotype was composed of six large metacentric, eight large acrocentric, six large telocentric, four medium metacentric, six medium submetacentric, six medium acrocentric, four medium telocentric, four small metacentric, two small acrocentric and four small telocentric chromosomes. The Ag-NOR banding showed a single pair of Ag-NORs adjacent to the telomeric position of the short arm of the chromosome pair 8.

SummaryHere we report natural autotetraploid and chromosomal characteristics in the subfamily Botiinae from Northeast Thailand. Kidney cell samples were taken from tiger botia (Syncrossus helodes), red-finned loach (Yasuhikotakai modesta), silver botia (Y. lecontei) and skunk botia (Y. morleti). The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the tetraploid chromosome numbers of S. helodes, Y. modesta, Y. lecontei and Y. morleti were 4n (natural autotetraploid)=100 for all species, and the fundamental numbers (NF) were 122 for all species. The presences of metacentric, submetacentric, and telocentric chromosomes were 12-10-78 for all species. No cytologically distinguishable sex chromosome was observed. The nucleolar organizer regions (NORs) were observed at the region adjacent to the short arms of a pair of submetacentric chromosome for all species. These results show the evolutionary relationship between species of loach fish from Thailand. The karyotype formula was deduced as:S

The first chromosomal characteristic of F 1 hybrid catfish from Thailand was studied. Kidney cell samples were taken from four male and four female fish. The mitotic chromosome preparations were done directly from kidney cells. Conventional staining technique was applied to stain the chromosomes. The results showed that the diploid chromosome number of Mekong giant catfish (Pangasianodon gigas) striped catfish (P. hypophthalmus) and spot pangasius (Pangasius larnaudii) P. hypophthalmus were 2n=60, the fundamental number (NF) was 108 in both males and females. The chromosomes presences of metacentric, submetacentric, acrocentric, and telocentric chromosomes were 27-11-10-12 and 25-12-11-12, respectively. While the chromosomes of P. gigas, P. hypophthalmus, and P. larnaudii (parents) presences of metacentric, submetacentric, acrocentric, and telocentric chromosomes were 28-12-12-8, 26-10-8-16, and 24-14-14-8, respectively. Results obtained will increase our basic knowledge of the cytogenetics of the family Pangasiidae which could form the basis for future research and provide data to ensure their survival. The karyotype formulae could be deduced as: × , 2 (60) = 27m +11sm +10a +12t × , 2 (60) = 25m +12sm +11a +12t P. gigas P. hypophthalmus n P.larnaudii P. hypophthalmus n