In this study, two agricultural synthetic insecticides were examined for their genotoxic and cytotoxic effects on root tip cells of Allium cepa, namely, Emar non-systemic Insecticide, which is used to eliminate worms on rodents, and Confidor Systemic insecticide that targets sucking insects.Two concentrations (0.2 and 0.1 ml/L) of Emar and one concentration (0.15 ml/L) of Confidor were used for four different time periods (8, 12, 16 and 24 h); tested dosages were assessed for genotoxic and cytotoxic effects to mitotic chromosomes of Allium cepa root tip cells. The results indicate that both insecticides were genotoxic, as they decrease the mitotic index and increase chromosomal aberration. The observed effects were significant after treatment with 0.1 ml/L and 0.2 ml/L of Emare; also, treament with 0.15 ml/L of Confidor was significant at p>0.05 and cytotoxic, especially after treatment for a long time (16, 24 h). The types of chromosome aberration observed were stickiness, distributed, C-metaphase, C-anaphase, lagging chromosome, binucleate cell and bridge.
Chromosomal characteristics of Nile tilapia (Oreochromis niloticus) from mitotic and meiotic cell division were studied. Blood samples were taken from five male and five female fish. Fish chromosome preparation was conducted by T-lymphocyte cell culture and squash technique from testis. The chromosomes were stained by conventional and Ag-NOR staining techniques. The results showed that the diploid chromosome number of O. niloticus was 2n=44 and the fundamental number (NF) was 58 in both male and female. The types of chromosomes were present as 2 large acrocentric, 2 small submetacentric, 10 small acrocentric, and 30 small telocentric chromosomes. There are no strange size chromosomes related to sex. We also observed distinctive secondary constriction/NORs at the region adjacent to the short arms near telomere of a pair of submetacentric chromosomes. The karyotype formula of O. niloticus is as stated: 2n (diploid) 42=La2+S2sm+Sa10+St30.
Karyological analysis and morphometrics of Horsfield's bat (Myotis horsfieldii) from Thailand were studied. Blood samples were taken from five male and five female bats. After standard whole blood lymphocytes were cultured at 37°C for 72 h in presence of colchicine, metaphase spreads were performed on microscopic slides and air-dried. Conventional staining and GTG-banding techniques were applied to stain the chromosome. The results showed that the diploid chromosome number of M. horsfieldii was 2n=44, the fundamental number (NF) was 52 in both male and female. The types of autosomes observed were 6 large metacentric, 4 medium telocentric, 2 small metacentric, 2 small submetacentric, and 28 small telocentric chromosomes. The X chromosome was a large submetacentric chromosome and the Y chromosome was a small acrocentric chromosome. From the GTG-banding technique, the number of bands and location in M. horsfieldii was observed to be 195, and each chromosome pair could be clearly differentiated. Six external morphological characters were measured as well as 13 cranial and dental measurements. The karyotype formula of M. horsfieldii is as follows: 2n (44)=Lm6+M4t+Sm2+S2sm+S28t+XY
Interpopulational variation of nucleolar organizer region (NOR) position and karyotypic analysis of Siamese catfish (Pseudomystus siamensis) in Thailand were studied. The samples were taken from three locations (8 populations); the mitotic chromosome preparations were conducted directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosomes number was 2n=50 and the fundamental number (NF) was 96 in both sexes. The karyotype of P. siamensis showed two new cytotypes for this species. The chromosome of cytotype A and B showed the presence of metacentric, submetacentric, acrocentric and telocentric autosomes as 22–18–6–4 and 20–20–6–4, respectively, without any apparent sex chromosomal heteromorphism. Data obtained from chromosomal banding technique further suggests an interpopulation NOR polymorphism. Such variation is possibly caused by paracentric inversion. In addition, a pair of the long arms of chromosome pair 2′ in cytotype A and chromosome pair 12′′ in cytotype B showed clearly observable NORs. The karyotype formulas of cytotype A and B for P. siamensis could be deduced as: Cytotype A: 2n (diploid) 50=L6m+L6sm+L2a+Mm16+M12sm+Ma4+Mt2+St2 Cytotype B: 2n (diploid) 50=L2m+L6sm+Mm14+M12sm+Ma6+Mt2+S4m+S2sm+St2.
Two wild Solanum species, viz. S. violaceum, S. sisymbrifolium, and a putative hybrid between ♀ S. violaceum and ♂ S. melongena were investigated to elucidate their genomic information. For this reason, the orcein and CMA-stained karyotypes of these three specimens were compared. In addition, RAPD with five primer combinations were conducted to make comparative DNA finger printing. The three specimens were found to possess 2n=24 chromosomes. The karyotypes of the three specimens consisted of mostly metacentric chromosomes with no gradual decrease in chromosomal length suggesting symmetric karyotypes. A pair of CMA-positive satellites was found in both the members of pair II of S. violaceum and the putative hybrid. The CMA-karyotype of S. sisymbrifolium was different from the other two specimens. Solanum violaceum and the putative hybrid showed exactly the same DNA finger printing in two primers (Batch-7736-037 and Batch-7736-039) and almost the same in the other three primer combinations. On the other hand, the RAPD finger printing of S. sisymbrifolium was quite different from the other two specimens. The comparative karyotype and RAPD analysis clearly indicated that the putative hybrid was not actually a hybrid between S. violaceum and S. melongena, but rather showed a close resemblance to the mother plant.
Although the occurrence of reciprocal translocation has already been discovered in plants, this is the first report on the striking phenomenon of reciprocal translocation (RT) induced through combined treatment in Brassica campestris L. accession number-IC363713. The seeds were subjected to four doses of gamma rays i.e.15, 30, 45, 60 Kr, followed by 0.3% EMS solution, and were sown in triplicates. Occurrence of RT was identified by the reduced reproductive success of plants, which was authenticated by cytological analysis that revealed the high incidence of multivalent association, forming either a ring or a chain. Rings were discerned to occur in alternate orientation, forming eight-shaped structure while simple loops were noticed erratically when the chromosomes were oriented adjacently. On the other hand, the lack of chiasmata in chromosomes was the cause of chains as multivalent association. No such phenomenon has been observed in non-treated sets. Moreover, the spectrum of multivalent association (MA) and univalents in the pollen mother cells (PMCs) from diakinesis to metaphase-I has been found to be increased in parallel with the dose of treatment, although the frequency of bivalents showed a gradual decline in their percentages. The frequency of quadrivalents has prevailed both in ring and chain forms, other than trivalent, hexavalent and other associations. Meanwhile, pollen fertility drastically decreased with the increasing trend of multivalent association. Notwithstanding RT, various other structural chromosome abnormalities, such as unequal separation, laggards and bridges during meiotic course, were recorded.
A population of cultivated Aloe barbadensis Mill. displayed various types of chromosomal configurations at anaphase/telophase-I and II due to inversion heterozgosity. The population was characterized by the presence of bridges and fragments because of various numbers and positions of cross-overs in the inversion loop. The inversion heterozygote had very low pollen fertility.
Details of male meiotic course and pollen fertility have been investigated in 45 species of dicotyledonous plants from the chromosomally unexplored area of the Mandi district, between the altitudinal ranges of 800 to 3360 m. All the species have been worked out cytologically for the first time from the study area. The meiotic chromosome count of n=9 for Impatiens micranthemum is the first ever chromosome report for the species. A new intraspecific 12x cytotype (n=42) has been reported in Potentilla gerardiana, supplementing the earlier reported cytotypes (2x, 8x). A new cytotype has been reported in Gentiana argentea (n=9), supplementing the earlier Indian report of n=10. Out of a total 45 species, 31 species (68.89%) showed normal meiotic course and high pollen fertility (91–100%), while 14 species (31.11%) depicted various meiotic irregularities and some pollen sterility (4–40%). The phenomenon of cytomixis involving inter-pollen mother cells (PMCs) migration of chromatin material has been reported in 3 species, Clematis grata (n=8), Gentiana aprica (n=10) and Lamium album (n=9). In these species, cytomixis induces various meiotic abnormalities (enucleated, hypo-, hyperploid, tripolar and multipolar PMCs, chromatin stickiness, laggards and chromatin bridges at anaphases and telophases and micronuclei) and consequently some pollen sterility and variable sized pollen grains. Besides, non-synchronous disjunctions of bivalents at anaphases, abnormal spindles, and interbivalent connections during diakinesis/metaphase-I, univalents and multivalents have also been reported in certain cases. The chromosome counts in the remainder of the species substantiate previous counts by other researchers.
Most Morus species are diploid, having 28 chromosomes, but a few species, specifically, M. tiliafolia Makino, Morus cathyana and M. nigra L., are higher polyploidy. In these species, the chromosome number varies from 2n=28 to 2n=308, with ploidy level from x to 22x. In the present study, three diploid mulberry varieties, namely, V1, S13 and S34, have been analyzed for detailed meiotic studies. Based on chromosome configuration and other meiotic behaviour, x=14 has been considered as the basic number of the genus. Meiosis shows marginal differences. Various meiotic abnormalities, such as the occurrence of one large chromosome at metaphase I, unequal separation at anaphase I, the presence of laggards and precocious movement of chromosomes at anaphase II, and two micronuclei at tetrad, have been observed. The low pollen fertility and seed sets may be due to irregular chromosomal pairing and separation rather than due to genetic or physiological causes.
Five commercial cultivars of Vigna unguiculata ssp. sesquipedalis (L.) Verdc., viz. Lalbanie, Kagornatki, BARI Borboti-1, White Bean, and Saba, were investigated cytogenetically and at the molecular level for characterization. Although the five cultivars possessed an identical chromosome number (2n=22), they showed variation in respect of other karyotype features. Maximum metacentric chromosomes were found in Saba. The karyotype formulae of Lalbanie, Kagornatki, and White Bean were more or less similar while BARI Borboti-1 was quite different, since in addition to metacentric and sub-metacentric chromosomes, a telocentric chromosome is present in its karyotype. The total length of 2n chromosome complements of Saba was the largest. Different total lengths of diploid complements among these cultivars indicated the deletion of heterochromatic regions. The five cultivars showed distinct CMA-banded karyotypes which were specific for each variety. Heteromorphicity in respect of CMA-band was found in Lalbanie and Saba, suggesting the deletion of heterochromatic banded portion from the respective chromosomes. The highest percentage of GC-rich regions was found in BARI Borboti-1, while the lowest was in Saba. The reason for the variation in the percentage of GC-rich regions is probably the tandem duplication of GC-rich repeats. In spite of a few common RAPD bands, each cultivar has distinct RAPD-fingerprinting pattern. The common band revealed that the five cultivars share similar fragments. Lalbanie, BARI Borboti-1, White Bean, and Saba showed unique bands, useful as specific markers for these varieties. Therefore, with the help of cytogenetical and RAPD analysis, it was possible to characterize each cultivar of Vigna unguiculata ssp. sesquipedalis (L.) Verdc.
Mutagenic effectiveness and efficiency is an important factor for the selection of a mutagen for a mutation breeding program. Mutagenic effectiveness is a measure of the frequency of mutations induced by a unit mutagen dose, while mutagenic efficiency is a measure of the proportion of mutations in relation to undesirable changes such as lethality, sterility, meiotic aberrations etc. The present study envisages the mutagenic effectiveness and efficiency of individual and combined treatments of chemical and physical mutagens i.e. sodium azide (individual), gamma rays (individual) and sodium azide+gamma ray (combined). For the individual treatment of sodium azide, the seeds of the Sesbania cannabina variety ND-1 were treated with 0.5% solution of sodium azide (SA) for four different time durations, i.e. 3, 5, 7, and 9 h, and for the individual treatment of gamma rays, dry and healthy seeds were treated with 20, 40, 60, and 80 Kr doses of gamma rays. For the combined treatment, the seeds were exposed to four different doses of gamma rays (20, 40, 60, and 80 Kr) and after irradiation seeds were treated with 0.5% solution of sodium azide for 3 h. After treatment, seeds subjected to individual and combined treatment were sown in randomized block design to raise the M1 generation and a study was conducted on germination percentage, survival percentage, pollen fertility percentage, and chromosomal aberrations at different doses of the individual and combined treatments.
Pimelodella is one of the genera belonging to the family Heptapteridae consisting of endemic neotropical fishes; it has shown a wide variability in karyotype. The present study aimed to evaluate cytogenetically two species belonging to the genus Pimelodella from Iguatemi River Basin, MS, Brazil. In the specimens of P.avanhadavae, the diploid number was 2n=52 chromosomes, distributed in 24m+20sm+08st, with multiple NORs systems. The heterochromatin was weakly visualized with C-banding in telomeric and/or centromeric regions of a few chromosomes. For the specimens of P. gracilis, the diploid number was 2n=46 chromosomes, distributed in 20m+18sm+06st+2a to with a simple NORs system, and heterochromatic blocks in the centromeric and telomeric regions, with variable intensity of staining, and conspicuous interstitial blocks. The two species of Pimelodella differ in diploid number and karyotypic formula, indicating that chromosomal rearrangements, such as fissions and/or centric fusions, may have occurred during the diversification of these two species.
When interphase cells are fused with mitotic cells, loosely distributing chromatins in nuclei are induced to form prematurely condensed chromosomes. In this paper we report a modified protocol to unequivocally detect prematurely condensed chromosomes in human peripheral blood lymphocytes that were fused with mitotic Chinese hamster ovary (CHO) cells. To examine cell fusion-mediated premature chromosome condensation (PCC), we conducted morphological analysis by differential interference contrast microscopy and molecular cytogenetic analysis by fluorescence in situ hybridization using pan-centromeric and telomeric peptide nucleic acid (PNA) probes. These modified procedures may serve to improve the usefulness of the technique of PCC in cytogenetic investigations.
Eight male sterile-female fertile mutants possessing a similar phenotype (semi-dwarf with dark green cup shaped pinnae), normal meiotic chromosome behavior and 100.0% sterile pollen grains were scored at M2 (0.1% over mutagenized population; 7845 plants scored) following different mutagen treatments (0.25%, 2 h EMS; 0.5%, 4 h dES; 1.00%, 2 h H2O2; 0.25%, 4 h NaN3; 0.50%, 4 h NH2OH; 100 Gy, gamma irradiations) to dry seeds (moisture content: 19.04%) of Nigella sativa L. (Family: Ranunculaceae; common name: black cumin). The marked phenotype of the M2 mutant plants did not persist in subsequent generations (M3 and M4). Male sterility is reported to be of the non-structural nuclear type. Segregation studies revealed that male sterility was monogenic recessive to male fertility. The male sterile plant type assessed over the generations (M2 to M4) was characterized morphologically, palynologically (pollen attributes studied following SEM analysis, DAPI staining and using stain tests for viability), and cytologically in relation to male fertile normal plants. The results obtained were discussed.
Cells from different lineages may exert a different growth capacity following transplantation. To compare the efficacy of different cells on rebuilding hematopoietic function, peripheral leukocytes, spleen cells, liver cells and bone marrow cells derived from GFP transgenic male mice were transfused into irradiated female mice. GFP-positive cells in the peripheral blood of female recipients were detected 20, 40, or 60 days after transplantation. At the 180th day after transplantation, mice were sacrificed and bone marrow cells were collected to detect the Y chromosome-positive rate. Results showed that GFP-positive cells appeared as early as 20 days after transplantation in peripheral blood, and some cells had differentiated to CD4+ or CD8+ T cells. The differentiation rate was different among the four types of donor cells. The Y chromosome-positive rate in bone marrow and the GFP-positive rate in peripheral blood were positively correlated. Although all 4 types of cells were able to rebuild hematopoietic function, spleen and bone marrow cells showed the highest capacity, followed by liver cells. Leukocytes showed the least reconstitution efficacy.