The 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: 2n (50)=L2m+L2sm+M2a+S2m+S6sm+S4a+S4t+28 microchromosomes
The present study aims to construct the karyotype and idiogram of the Northeastern butterfly lizard (Leiolepis reevesii rubritaeniata). Specimens were collected from Khon Kaen Province, Northeast Thailand. Lizard chromosome preparation was conducted by the squash technique using bone marrow and testis. Conventional staining and NOR-banding techniques were applied to stain the chromosomes with Giemsa's solution. The results showed that the number of diploid chromosome is 2n=36, while the fundamental number (NF) is 24 in both males and females. The types of macrochromosomes were six large metacentric, four medium metacentric, two small metacentric, and 24 microchromosomes. Nucleolar organizer regions (NORs) are located at the secondary constriction of long arm chromosomes, near the telomeres of the largest metacentric chromosomes. The karyotypes are not different for the sex chromosomes of both males and females. The karyotype formula is as follows: 2n (36)=L6m+M4m+S2m+24 microchromosomes
The first cytogenetics of the puff-faced water snake (Homalopsis buccata) from Khon Kaen Province, Thailand was obtained from the present study. Mitotic chromosome was prepared directly from the spleens of specimens after in vivo colchicines treatment. The metaphase spreads were performed on microscopic slides and air-dried. Conventional staining, Ag-NOR banding, and GTG-banding techniques were applied to stain the chromosome with Giemsa's solution. Results showed that the number of diploid chromosome was 2n=36, while the fundamental number (NF) was 52 in both males and females. The types of macrochromosome were four large metacentric, two medium metacentric, six small metacentric, and two small acrocentric chromosome, and 20 microchromosomes. It was found that nucleolar organizer regions (NORs, the representative of chromosome marker) locate on the long arms near centromeres of a pair of microchromosomes, pair 15. The Z chromosome was a small metacentric chromosome, while the W chromosome was a small submetacentric chromosome. From the GTG-banding technique, it was found that each chromosome pairs could be clearly differentiated and the numbers of bands in the H. buccata was 109. The karyotype formula is as follows: 2n (36)=L4m+M2m+S6m+S2a+20 microchromosomes+sex chromosomes (ZW)
The study investigated the mitotic chromosomes of two variants of C. benghalensis var. benghalensis and C. forskalaei from Nigeria using classical cytogenetic techniques. The two variants of C. benghalensis var. benghalensis have the same diploid chromosome number of 2n=22 and the same karyotype formula of (8 m+10 sm+4 st) chromosomes. The two variants of C. forskalaei have the same diploid chromosome number of 2n=30 and the same karyotype formula of (14 m+6 sm+10 st) chromosomes. Terminal satellites were observed on the short arms of sub-terminal chromosome pair number 13 of C. forskalaei cf1 and the short arms of sub-terminal chromosome pair number 7 of C. forskalaei cf2. No satellites were observed in the chromosomes of the two variants of C. benghalensis. The chromosomes of the two variants of C. benghalensis var. benghalensis are mainly medium sized (1.00–1.43 µm) while the chromosomes of C. forskalaei are mainly small sized (0.47–0.97 µm). Results indicate interspecific variation in chromosome numbers and forms in the two Commelina species investigated.
Cytomixis associated with chromosomal anomalies was recorded in the meiotic division of pollen mother cells of the wild genotypes of Chlorophytum tuberosum (Roxb.) Baker for the first time. The migration of chromosomal substances was more prevalent in Meiosis-I than Meiosis-II. Cytomixis has been found both in juxtaposed cells by direct contact as well as between remote cells through cytoplasmic strands. During cytomixis, various chromosomal abnormalities, such as chromosomal stickiness, laggards, chromosomal bridges, unequal separation of chromosome, micronuclei formation and loss of chromosome, were recorded. A significant number of empty pollen formations leading to pollen sterility was recorded which is assumed to be a direct result of cytomixis.
The aim of this study was to analyze the meiotic behavior and to estimate the meiotic index and the pollen grain viability of three papaya genotypes, male (Cariflora) and hermaphrodite (Golden and UENF/CALIMAN01). In considering of the fact that the genotypes have different flower sizes, initially, meiotic stages were defined in relation to bud size, and, after that, meiosis was observed in the three genotypes. To observe meiosis, flower buds of different sizes were collected and the length of each bud was measured using graph paper. Once the measurements had been taken, two slides were prepared for each flower bud by squashing the anthers in 1% acetic carmine solution. Slides were observed under an optical microscope and for each bud, size was determined as indicating one of three stages, depending on meiotic phase: pre-meiotic, meiotic stage, or post-meiotic stage. In this way, meiosis was observed for the three genotypes, with particular attention given to possible irregularities in cell division in relation to prophase I. It was observed that there is a relation between flower bud size and meiosis. In general, meiosis was normal, but all genotypes showed some meiotic irregularity, with laggard chromosome being the most common. The Cariflora (male) genotype had a higher frequency of irregularities compared to the hermaphrodite genotypes. The meiotic indices estimated for the Golden, UENF/CALIMAN01, and Cariflora genotypes were 92.6%, 91% and 76.9%, respectively; however, the pollen grain viability, on average, was higher than 90%. In conclusion, the meiotic behavior of male and hermaphrodite genotypes was similar, and all three genotypes had some degree of meiotic abnormality.
In continuation of past trials to develop a triploid chamomile cultivar, flow cytometer investigations to determine spontaneous ploidy variation in established cultivars of Matricaria recutita were carried out. The screening of a total of 120 plants of three cultivars included general analysis of ploidy level and specific differentiation of aneuploids. Microscopic counts of mitotic chromosome numbers in some reference individuals and comparison of flowering and seed characters between cultivars and ploidy levels were included. Results showed ploidy level-deviants in two of three cultivars and a clear segregation of a uniform diploid unit of plants against a dispersive tetraploid unit with numerous hyper- and hypotetraploid aneuploids, but no triploids. The tendency to flower was significantly higher in diploid plants (vs. tetraploids), whereas the flowering duration of plants and the flowering duration of single capitula rose slightly with increasing ploidy level. Matricaria recutita seems not to produce triploids easily, as none were observed; they neither occurred through spontaneous formation nor after controlled crossing. However, autotetraploid aneuploids with varying number of chromosomes emerged frequently.
The meiotic chromosome number and behavior of 12 Iranian populations belonging to six Astragalus species, A. submitis, A. raddei, A. crassispinus, A. ebenoides, A. szovitsii and A. lalesarensis of A. sect. Megalocystis, are presented here. All taxa studied are diploid and possess 2n=2x=16 chromosome number, consistent with the proposed base number of x=8 from ICPN. Although the taxa displayed regular bivalent pairing and chromosome segregation at meiosis, some meiotic abnormalities observed, included varied degrees of fragmented chromosomes, cytomixis, asynchronous nucleus, laggard, sticky and forward chromosomes, desynapsis and unequal polars.
We have isolated from teratomas a residual cell population reluctant to differentiate in the tumor to ectoderm, mesoderm and endoderm. The main characteristics of this population, compared with undifferentiated R1-cells were: persistent expression of Oct4 gene, modest expression of primordial germ cell markers, karyotype alterations and the capability to form teratomas once transplanted again to immunodeficient mice. The aim of the present report is to further characterize this cell population by studying two aspects that could be related to their teratogenecity: LIF insensitivity and the expression of DNA-damage activated proteins. We have used Western blot and immunocytochemistry to address these questions. Persistent phosphorylation of STAT3 was observed in the absence of leukemia inhibitory factor, explaining the insensitivity to the cytokine compared to R1-embryonic stem cells cultured in vitro. Second, we analyzed by Western-blot the expression level of different proteins involved in DNA damage response. Teratoma-isolated cells presented high expression levels of all assayed proteins, except for Rad9. In addition, cytoimmuno-detection using histone γH2AX antibody indicated the presence of DNA instability linked to double strand breaks. The data shown here, despite being preliminary, could help to explain the teratogenecity of this particular cell population.