Chromosome preparation from gill tissue of the tropical oyster (Crassostera belcheri Sowerby, 1871) collected from an oyster farm in Kantang District, Trang Province, southern Thailand was studied by conventional staining and Ag-NOR baining techniques. The result revealed that the diploid chromosome number is 2n=20 and the fundamental number (NF) is 40. The karyotype has revealed 10 large metacentric and 10 medium metacentric chromosomes. One pair of nucleolar organizer regions (NORs) was apparent on the short arm telomeric region of chromosome pair 10. Basic information on the cytogenetics of the C. belcheri may be useful for future studies on interspecific hybridization and polyploidy. The karyotype formula of C. belcheri is as follows:

The first chromosome analysis and nucleolar organizer region (NOR) pattern of the humpback cardinalfish (Fibramia lateralis) were studied. Samples from 10 male and 10 female fish were collected from the Andaman Sea and Gulf of Thailand. Mitotic chromosome preparations were prepared directly from kidney tissues. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of F. lateralis was 2n=46, and the fundamental numbers (NF) were 54 in both sexes. The karyotype consisted of 8 large acrocentric, 12 large telocentric, 24 medium telocentric and 2 small telocentric chromosomes. Moreover, the results indicated that the region adjacent to the telomere of the short arm of the second acrocentric chromosome pair showed clearly observable nucleolar organizer regions (NORs). Strange size chromosomes related to sex were not observed. The karyotype formula for F. lateralis is as follows:

This is the first nucleolar organizer region (NOR) polymorphism and chromosome analysis of Banggai cardinalfish (Pterapogon kauderni Koumans, 1933). Kidney cell samples were taken from 10 male and 10 female fish. Mitotic chromosome preparations were prepared directly from kidney cells. Conventional and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of P. kauderni was 2n=46, and the fundamental number (NF) was 92 in both males and females. The types of chromosomes were 6 large acrocentric, 4 medium metacentric, 14 medium submetacentric, and 22 medium acrocentric chromosomes. The results indicated that the short arm subtelomeric of the acrocentric chromosome pair 13 showed clearly observable NORs. This finding exhibited that three NOR polymorphism patterns were found: 1) homomorphic which shows an equal size of both chromosome pair 13 (13a13a), 2) heteromorphic that displays different sizes of NORs of chromosome pair 13 (13a13c) and 3) heteromorphic which is found in only one homologous chromosome pair 13 (13a13b). There was no observation of strange size chromosomes related to sex. The karyotype formula for P. kauderni was:

We report the first chromosome analysis in the Indian vagabond butterflyfish (Chaetodon decussatus) and lined butterflyfish (C. lineolatus) from Andaman Sea, Phuket Province, Thailand. Kidney cell samples were taken from four male and four female fishes. The mitotic chromosome preparation was directly prepared from kidney cells. The chromosomes were stained with conventional and Ag-NOR staining techniques. The results showed that the diploid chromosome number of C. decussatus and C. lineolatus was 2n=48, and the fundamental number (NF) was 48 in both males and females. The chromosomes were present as large telocentric and medium telocentric chromosomes in numbers of 24–24 and 22–26, respectively. There was no observation of strange size chromosomes related to sex. After Ag-NOR banding technique, a single pair of nucleolar organizer regions (NORs) was observed on the long arm centromeric region of medium telocentric chromosome pair 18 in C. decussatus and on the long arm subcentromeric region of medium telocentric chromosome pair 17 in C. lineolatus. The karyotype formulas could be deduced as:

The first chromosomal characteristics of nucleolar organizer regions (NORs) and karyological analysis of triangle butterflyfish (Chaetodon triangulum) and yellow butterflyfish (C. andamanensis) from Andaman Sea, Phuket and Phang Nga Province, Thailand, were studied. Kidney cell samples were taken from five male and five female fish. Mitotic chromosome preparations were conducted using 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 chromosome. The results showed that the diploid chromosome number of C. triangulum and C. andamanensis was 2n=48, and the fundamental numbers (NFs) were 48 and 52, respectively. Karyotpes were present as 46 large telocentric and two medium telocentric chromosomes in C. triangulum; and 2 large metacentric, 8 large telocentric, 34 medium telocentric, 2 medium acrocentric, and 2 small telocentric chromosomes in C. andamanensis. No strange sized chromosomes related to sex were observed. After the Ag-NOR banding technique, one pair of NORs was observed on the long arm centromeric region of large telocentric chromosome pair 21 in C. triangulum and on the long arm subcentromeric region of the largest metacentric chromosome pair 1 in C. andamanensis. The karyotype formulas are as follows:

The study aimed to assess water quality parameters and heavy metal contamination in water, sediment and Nile tilapia (Oreochromis niloticus). Heavy metal concentrations in water were compared to Thailand’s standard limits, and chromosomal aberrations in O. niloticus from contaminated water were compared with O. niloticus from an unaffected area. The samples were collected from a domestic wastewater canal, water quality parameters were assessed, and heavy metal concentrations (Pb, Cd, Cr, Cu, Fe, Mn, Ni, and Zn) in the water, sediment and fish were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES). The water quality parameters did not exceed standard values. The concentrations of heavy metals in the water and sediment did not exceed Thailand’s standards, but the Ni concentration in the water was higher than the standard limits. Similarly, heavy metal concentrations in O. niloticus were also below the standard limits. Only the Cr concentration in O. niloticus tissues exceeded the standard limits. The diploid chromosome number of O. niloticus from both areas was 2n=44 and the chromosomal damage of O. niloticus in the affected area was higher than that in the unaffected area. There were six types of chromosomal aberrations: single chromatid break, single chromatid gap, centromeric gap, fragmentation, deletion and dicentric chromosomes. The most common chromosomal abnormality in the fish samples from the affected area was single chromatid gap, and the difference in chromosomal breakages in O. niloticus between the areas was significant (p＜0.05).

The present study aims to analyze concerned karyotyping and idiograming of the three-spot damselfish (Dascyllus trimaculatus) in Thailand. Chromosomes were prepared from kidney tissues of fish reared at Institute of Marine Science, Burapha University, Chonburi Province. The mitotic chromosomes were harvested by the colchicine-hypotonic-fixation-air drying method. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that D. trimaculatus had 2n=48, and the fundamental number (NF) was 50 without heteromorphic sex chromosomes. The types of chromosomes are 2 large acrocentric, 36 large terocentric and 10 medium telocentric chromosomes. The Ag-NOR banding exhibited that a single pair of NORs was presented on the short arm region of the large acrocentric chromosome. Basic knowledge on cytogenetics of D. trimaculatus would be applied for support of further studies on breeding, conservation and chromosome evolution in this fish. The karyotype formula of D. trimaculatus is as follows:

We report the first chromosome analysis in the ocellated dragonet (Synchiropus ocellatus) and picturesque dragonet (S. picturatus) from Thailand. Kidney cell samples were taken from five male and five female fishes. The mitotic chromosome preparation was prepared 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 S. ocellatus and S. picturatus were 2n=40, and the fundamental number (NF) was 40 in both males and females. The chromosomes were present as large telocentric, medium telocentric and small telocentric chromosomes in numbers of 16–18–6 and 14–24–2, respectively. No morphological difference was identified between sex chromosomes of male and female specimens. After Ag-NOR banding technique, a single pair of nucleolar organizer regions (NORs) was observed on the long arm centromeric region of large telocentric chromosome pair 5 in S. ocellatus and chromosome pair 4 in S. picturatus. The karyotype formulas could be deduced as:

The cytogenetics of the ornamented pygmy frog (Microhyla fissipes), painted chorus frog (M. pulchra) and narrow-mouthed frog (M. heymonsi) were studied in the aspect of chromosome numbers, morphology and nucleolus organizer region (NOR) locations. For this present study, we provided the karyotype and idiogram of these three species by conventional and Ag-NOR staining techniques. The 10 male and female samples of those three species were collected in Northeast Thailand. The metaphase chromosome preparations were prepared from the bone marrows by the standard protocol. To stain the chromosomes, 10% Giemsa’s and 50% silver nitrate were applied. The results showed that all three species had the same diploid chromosome number of 2n=24, and fundamental numbers (NF) were 48 in both males and females. The chromosomes of M. fissipes were comprised of 16m+6sm+XY (X and Y were metacentric chromosomes). M. pulchra had chromosomes consisting of 12m+12sm and M. heymonsi had chromosomes comprising of 18m+6 with no obvious difference in size of sex chromosomes for the two species. M. fissipes and M. pulchra had the same NORs adjacent to the subcentromeric on the long arm of chromosome pair 9, while M. heymonsi had the NOR location on the short arm of chromosome pair 2 close to the centromere. For this case, we suggested that chromosome morphology and the NOR location is still a useful cytological character for taxonomic and evolutionary studies.

The standardized karyotype and idiogram of the Bengal monitor lizard (Varanus bengalensis) from the Kalasin Province of Thailand were studied. Blood samples were taken from male and female lizards. The standard T-lymphocyte cell was cultured at 26°C for 96 h. The mitotic chromosomes were harvested by colchicine-hypotonic-fixation-air drying technique. Conventional staining, Ag-NOR banding and C-banding techniques were applied to stain the chromosome with 20% Giemsa’s solution. The results showed that the number of diploid chromosome was 2n=40, while the fundamental number (NF) was 54 in males and 55 in females. The types of macrochromosomes were 4 large metacentric, 4 small metacentric, 6 small submetacentric, 2 small telocentric macrochromosomes and 24 microchromosomes. The Z chromosome is the small telocentric chromosome, while the W chromosome is the small metacentric chromosome. In addition, the short arm pericentromeric region of chromosome pair 1 showed clearly observable nucleolar organizer regions (NORs). This data is the first report on polymorphism of NORs in V. bengalensis. The result showed that the heteromorphic of one male had a different size of NORs of chromosome pair 1 (1a1b), while one female had an equal size of both chromosome pair 1 with a homomorphic (1a1a). The karyotype formula is as follows:

Chromosomal analyses of the stripe tree skink (Lipinia vittigera Boulenger, 1894) from mitotic and meiotic cell divisions were studied. Bone marrow and testis samples were taken from five male and five female skinks. Skink chromosome preparations were conducted by squash technique from bone marrow and testis. The chromosomes were stained by conventional staining and Ag-NOR banding techniques. The results showed that the diploid chromosome number of L. vittigera was 2n=28, and the fundamental number (NF) was 44 in both males and females. The types of chromosomes were present as 8 large metacentric, 2 medium metacentric, 6 small metacentric macrochromosomes, and 12 microchromosomes. There was no observation of strange size chromosomes related to sex. Nucleolar organizer regions (NORs) appear to the telomere on the long arm of the largest metacentric chromosome pair 1 and medium metacentric chromosome pair 5. We found that during metaphase I on meiosis, the homologous chromosomes showed synapsis, which can be defined as the 14 bivalents and 14 haploid chromosomes at metaphase II as diploid species. The karyotype formula of L. vittigera is as follows:

The standardized karyotype and idiogram of the axis deer (Axis axis, Cervidae) at Khon Kaen Zoo, Thailand were established. Blood samples were taken from two male and two female axis deer. After standard whole blood T-lymphocytes were cultured at 37°C for 72 h in the presence of colchicine, metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, GTG-, Ag-NOR-banding and high-resolution techniques were applied to stain the chromosome. The results showed that the diploid chromosome number of A. axis was 2n=66 and the fundamental number (NF) was 70 in both male and female. The types of autosomes observed were 2 large metacentric, 2 large submetacentric, 2 large telocentric, 6 medium telocentric and 52 small telocentric chromosomes. The X chromosome was a large telocentric chromosome, and the Y chromosome was a small telocentric chromosome. The GTG-banding and high-resolution techniques provided that the respective numbers of bands and locations of A. axis were 246 and 294, and each chromosome pair could be clearly differentiated. In addition, the subtelomeric q-arm of chromosome pair 2 and the telomeric q-arm of chromosome pair 4 showed clearly observable nucleolar organizer regions (NORs) and secondary constrictions. Our results are the first reports of GTG-, high-resolution GTG- and Ag-NOR-banding techniques on this species. The karyotype formula of A. axis is as follows: