Among the Perciformes, Cichlidae represent the more specious group, geographically distributed in Africa, Asia and America. In the present work, 7 species of 5 genera of cichlids from the Paraná River (Misiones, Argentina) were cytogenetically characterized and discussed some aspects of the chromosome evolution. The following chromosome numbers and formulaes: were found for each analyzed species: Crenicichla niederleinii 2n=48 (6 M-SM; 42 ST-A), Crenicichla lepidota 2n=48 (6 M-SM; 42 ST-A), Gymnogeophagus sp. n. 2n=48 (2 M-SM; 46 ST-A), Gymnogeophagus balzanii 2n=48 (2 M-SM; 46 ST-A), Apistogramma trifasciata 2n=46 (16 M-SM; 30 ST-A), Cichlasoma dimerus 2n=48 (8 M-SM; 40 ST-A) and Bujurquina vittata 2n=44 (22 M-SM; 8 ST-A; 14 microchromosomes). The C-positive heterochromatin was observed preferentially in pericentromeric regions of some chromosomes and NORs at the secondary constriction on the first chromosome pair. In B. vittata the microchromosomes are not heterochromatic and the 5th pair shows short arms entirely stained and, in coincidence, the AgNORs appears located at the same region. The results obtained evidence a wide chromosomal variation, either in number and structure that could be integrated with morphological and molecular data in phylogenetic studies.
The long term exposure of living organisms to pesticidal residues present in our environment leads to several health hazards, of which genotoxity is of prime importance. The investigation on the effect of organophosphorous compound namely Chlorpyriphos on grasshoppers shows that Chlorpyriphos has induced chromosomal aberrations significantly with increase in concentration and duration of exposure to this compound. Hence, careful and controlled use of the stated pesticide is suggested.
Casearia sylvestris (Flacourtiaceae) is a plant which grows in wild and has been widely used in folk medicine. In this study, clastogenic/aneugenic properties of Casearia sylvestris crude ethanolic extract were evaluated using in vivo chromosomal aberrations (CAs) and micronucleus (MN) assays in rodents. The animals were treated by gavage with 3 concentrations of the extract: 150, 300 and 500 mg/kg body weight. Bone marrow cells from Wistar rats were collected 24 h after having been submitted to the MN and CAs test. Peripheral blood cells from Swiss mice were collected 48 and 72 h after having been submitted to the MN test. The results show that C. sylvestris extract does not induce a significant increase in mean values for micronucleated polychromatic erythrocytes (MNPCE) in Swiss mice and Wistar rats, or CAs in rat bone marrow cells, at the 3 tested doses, indicating that the extract showed no clastogenic/aneugenic effects on chromosomes of the rodent cells tested.
Karyotypic study of 3 species of Neolissocheilus hexagonolepis, Puntius ticto and P. chola belonging to family Cyprinidae, from Arunanchal Pradesh, India, were carried out. The diploid chromosome number in Neolissocheilus hexagonolepis was 100 with a chromosomal formula of 32m+16sm+6st+46T and fundamental arm number (FN) as 148. The other 2 species, Puntius ticto and P. chola have 50 chromosome with chromosomal formula of 28m+16sm+6st (FN=94) and 2m+2sm+46T (FN=54), respectively. The evolutionary significance of these 3 karyotypes was discussed.
The cytogenetic of Momordica charantia was studied using CMA3/DAPI and fluorescence in situ hybridization (FISH) techniques in order to characterize the features of its heterochromatin and the distribution of rDNA sites. The chromosomes observed were small and symmetrical. DAPI staining presented no band. The tests with CMA3 staining presented 4 positive bands at chromosome extremities, what indicates the presence of GC rich sites in this species. The studies with FISH showed 4 sites of rDNA 45S located at similar regions of those observed in CMA3 staining, and 2 sites of rDNA 5S at interstitial positions.
A modified method for the preparation of somatic chromosomes from goat (Capra hircus) has been introduced. The method is simpler, cheaper and quicker to all the existing protocols. The material is easily available at a low cost and the method produces almost equally effective results within a short period of time. Therefore, this material and the method have been recommended both for classroom demonstration of somatic chromosomes and research. In essence, the model describes the use of HBSS as incubation medium (replacing costly culture media) for bone marrow cells collected from slaughtered goat and incubated in HBSS in presence of a metaphase arrester (colchicine) for varying length of time to standardize the optimum dose. The cells were collected by centrifugation, suspended in hypotonic solution followed by fixation in an appropriate chromatin fixative. The slides were prepared by flame dry technique, stained in Giemsa solution for observation. The diploid number has been conformed as 60 acrocentric chromosomes of varying length. Construction of karyotype revealed a heteromorphic sex chromosome status, in male 2n=60, XY and in female 2n=60, XX. Spontaneous ploidal variation and the occurrence of Robertsonian fusion have been recorded. The advantage of this modified ‘pocket friendly’ technique has been discussed.
Largely in apomictic tropical grasses molecular markers analyses including identifying genes through association genetics approach requires DNA from large numbers of samples in short span of time. A simple protocol for DNA isolation from 5 apomictic tropical grass species namely Dichanthium annulatum, Heteropogon concortus, Sehima nervosum, Chrysopogon fulvus and Cenchrus glaucus is described. The method allows DNA extraction from as little as 0.2 to 0.3 g of leaves ground in liquid nitrogen, followed by DNA isolation in 1.5 ml Eppendorf tubes involving modified cetyltrimethylammonium bromide (CTAB) procedure using 1% polyvinylpyrrolidone (PVP) to remove polysaccharides. By using the method, a DNA yield up to 345 μg/g leaf tissues was obtained. The quality of the DNA was quite suitable not only for PCR-based markers analyses but also for restriction enzyme digestion. No or insignificant DNA was obtained in plant samples extracted from the fixed solution (alcohol, alcohol and chloroform, alcohol and ethylene diamine tetra acetic acid (EDTA)), thus the use of liquid nitrogen was inevitable.
The seeds of Nigella sativa were treated with 50, 100, 150, 200, 250, 300 Gy doses of gamma rays. A hexapetalous mutant was observed at 100 Gy dose in M1 generation. It was found to have increased seed weight and seed number as compared to the control plants. The chromosomal abnormalities at 100 Gy dose were also at the optimum level (17.10%). Therefore, this dose can be suggested to be beneficial for mutagenesis in plants.
The somatic chromosomes of Gossypium hirsutum, G. arboreum brown form, and G. arboreum white form were studied after staining with orcein, chromomycin A3 (CMA) and DAPI. Gossypium hirsutum possessed 2n=52 chromosomes with a gradual decrease in chromosome length. Both the forms of G. arboreum showed 2n=26 chromosomes with no such sharp decrease in chromosome length. The centromeric formula of G. hirsutum was 20 m+32 sm. The centromeric formulae of 10 m+16 sm and 14 m+12 sm were determined in the brown and white form of G. arboreum, respectively. Two big and 4 small CMA-positive bands were found in G. hirsutum. Four CMA-positive bands were found in G. arboreum brown form. The individual size of the band in the brown form was similar to that of big bands in G. hirsutum. Three CMA-positive bands were observed in the white form of G. arboreum which were smaller than those of the brown form. Gossypium hirsutum showed 3 DAPI-positive bands whereas no DAPI-positive band observed in brown and white form of G. arboreum. In G. hirsutum, 6 DAPI-negative bands appeared at the same location where CMA-positive bands were present. Three DAPI-negative bands were observed in brown and white form of G. arboreum at the same location where CMA-positive bands appeared. Reversible banding indicated the presence of GC-rich repeats. The banding pattern of G. hirsutum appeared to consider it as segmental allopolyploid. In spite of some similarities, the 2 forms of G. arboreum possessed unique fluorescent banding features.
Euglena grown to stationary phase in the dark without aeration accumulated lipids. When these high lipid cells are transferred to an inorganic medium and aerated, lipids were rapidly metabolized and the respiratory rate declined concomitant with the decline in cellular lipid content. Prolamellar bodies, propyrenoids and prothylakoids developed within the proplastid of dark aerated cells and the cells developed an increased capacity for chlorophyll synthesis manifested upon subsequent exposure to light. Lipid content did not decline in cells exposed to nitrogen and chlorophyll synthesis ability did not increase. The addition of an organic carbon source to cells at the start of aeration did not prevent lipid degradation. Organic carbon source addition and inhibitors of RNA and protein synthesis did however inhibit the development of an increased capacity for chlorophyll synthesis. These results suggest that oxygen triggers light independent proplastid development with the oxidative metabolism of lipids providing the carbon and energy for the synthesis of nucleic acids and proteins required for proplastid development in the dark.
Rearranged karyotypes of 2n=5 present in three plants of Haplopappus gracilis (2n=4) were cytogenetically analyzed to clarify the origin of an additional centromere in the chromosome complement. One of the plants was a progeny of the homozygote with normal chromosome 1 crossed with the heterozygote with normal and centromere-shifted chromosome 1. The other two plants were derived from seedlings irradiated with X-rays during early germination stage. The chromosome complement of 2n=5 found in the first plant was comprised of 3 normal chromosomes (one chromosome 1 and two chromosome 2) and two rearranged chromosomes each possessing a centromere at the subterminal position. All the chromosome complements of the irradiated plants were similar to each other and each consisted of three normal chromosomes (one chromosome 1 and two chromosome 2) and 2 rearranged chromosomes, one large and metacentric and the other, fragment-like. The origin of the additional centromere in each complement of 2n=5 is discussed from the point of chromosomal evolution in the genus Haplopappus.
Here we report the presence of 2B-chromosomes in Glycine max, which has yet not been reported. These chromosomes were observed in the natural population in 6 out of 85 plants tested in the variety JS90-41. In our case the B's however did not affect the morphology of the plant but had random meiotic behaviour. These chromosomes were smaller than the A-chromosomes and did not pair with them. The pollen fertility in the carrier and non-carrier plants was almost similar. About the possible origin of B-chromosomes in Glycine, it can be assumed that the B's observed in our case might have originated in the course of evolution to discard the inert heterochromatic part from the main nucleus.
Restriction endonucleases have been shown to digest fixed fish chromosomes, inducing specific and reproducible banding pattern. In the present paper the chromosome complements of the snakehead, Channa punctatus, were examined using restriction endonucleases like Eco RI, Hind III, Hinf I and Alu I. Among them Hind III and Hinf I are capable of producing G band like longitudinal bands. The results indicate a possible role of restriction endonucleases as a tool for cytogenetic characterization of fishes.
In this study, allelic variants, karyotypes and meiotic chromosome behavior were used to characterize triploid Taraxacum officinale. Five triploid common dandelions were used for the study. One plant had a D phenotype in the GOT alleles, and the others had heterodimetric isozymes of GOT. Based on the criterion by Morita et al. (1990a, b), 1 plant was determined to be T. officinale and the others were characterized as hybrid plants. Taraxacum officinale had a karyotype formulated as 2n = 24 = 1M+17m+3sm+3smcs. The mean number of associations per cell of this plant was 3.1III+4.8II+5.1I. Thus this plant was classified as a segmental allotriploid plant. In the 4 plants determined to be hybrids, 2 plants had the same karyotype represented as 2n = 24 = 4M+11m+1mcs+6sm+2smcs, suggesting they resulted from agamospermic production in the same strain of T. officinale. The remaining 2 hybrid plants also shared very similar karyotypes. However, their mean chromosome pairing in pollen mother cells were remarkably different each other. In the hybrid plants, 1 or 2 satellite chromosomes, within the 3 satellite chromosomes found in their somatic chromosome complements, were very similar to the satellite chromosomes of the T. officinale plant. These cytogenetic results demonstrate that these four dandelions all originated from hybrid plants.
Fluorescence in situ hybridization (FISH) using an Arabidopsis-type telomeric sequence (TTTAGGG)n probe to the mitotic chromosomes of Haplopappus gracilis (n=2) revealed the presence of Interstitial Telomere-like Repeats (ITRs) in at the subdistal position of the long arm of both chromosome pairs (1g and 2g). The H. gracilis genome (n=2) is generally thought to reconstitute from the n=4 complement of the allied species, H. ravenii. The sites we identified by FISH are in close proximity to the chromosomal rearrangement fusion points. This evidence supports the hypothesis that the karyotype of H. garacilis evolved from that of H. ravenii due to chromosome breakage and the subsequent end-to-end chromosome fusion.