Spathoglottis plicata Blume, a terrestrial orchid having prolonged inflorescence with beautiful lilac (pinkish purple) coloured flowers, is commercially important. Treatment of its seeds with sodium azide induced strikingly attractive flower colour modification exploiting seed culture protocols. Vacin and Went (VW) (1949) medium stimulated seed germination and after supplementation with ripe banana extract yielded maximum germination frequency in all cases; it was followed with ripe tomato extract and yogurt water (semi-solid liquor from fermented milk) in untreated and post-treated seeds respectively. The magnitude, however, reduced in treated seeds. Germination initiated usually on the 20th day of inoculation, while addition of yogurt water induced earlier germination by 9 days in the treated and 7 days in untreated samples. Repeatedly subcultured 60 days old plantlets were gradually acclimatized growing inside a hardening chamber and subsequently in a glass house. A treated plant with deep green leaves showed conspicuous variation from the mother strain by its charming milk-white flower colour and green floral bracts in contrast to lilac coloured flower and floral bracts in the latter. VM2 progeny retained the mutant phenotype and genetic uniqueness as indicated by specific PAGE protein banding profile. The mutant having completely different flower colour modification with milky whiteness possesses special floricultural significance and may, therefore, be treated as a new horticultural variety.
Unusual mitotic behavior of additional chromosomes present only in the germ line was reported for the dipteran families Cecidomyiidae, Chironomidae and Sciaridae, which are known to have complex chromosome cycles. In the chironomid Acricotopus lucidus all germ line limited chromosomes (=Ks) are eliminated from the future somatic nuclei during germ line-soma differentiation in early, still syncytial, embryonic divisions by remaining in the equatorial plane. But also in the germ line about half of the Ks are eliminated in the first mitotic division of the primary germ cells in the young gonads of first instar larvae. Until now not much is known about the cytogenetic processes in the course of germ line elimination of the Ks. In this study, the cytogenetic changes in the primary germ cells before, during and after the elimination mitosis were analysed in detail with DAPI stained gonad preparations.
Cytogenetic effects of dinocap were investigated in root tip cells of Allium cepa L. Mitotic index (MI), frequency of mitotic phases, mitotic and chromosomal abnormalities were determined in the presence of 0.00 (Control), 6.25 (EC50/4), 12.5 (EC50/2), 25 (EC50), 50 (EC50×2), 100 (EC50×4) mg/l concentrations of dinocap at 12, 24 and 48 h treatment. 100 mg/l concentration was toxic in all treatment times. Mitotic index decreased significantly with increasing of concentration in all treatment periods as compared to their controls. However, dinocap has not induced significant effect on the percentage of the mitotic stages except 25 and 50 mg/l at 48 h. This fungicide induced stickiness, C-mitosis, bridges, laggards, multipolarity, polyploidy, fragments, micronuclei and binucleated cells. In addition, in pretreated root tips, chromosome breaks, fragments, tetraploidy and sister union were detected.
Meiotic studies were performed on 11 populations of 8 Stipa species concerning polyploidy level, chiasma frequency and distribution, chromosomes association and segregation. All the species and populations studied possessed n=22 (2n=4x=44) chromosome number. The chromosome numbers of 3 species are reported for the first time. The populations and species studied differed significantly in their meiotic characteristics. Meiotic abnormalities observed included laggard chromosome formation, stickiness and cytomixis. Cytomixis led to the formation of aneuploid meiocytes. Unreduced pollen grains were observed in 2 species, which differed significantly in their size compared to the normal (reduced) pollen grains.
Solanum nigrum L. is a widely distributed polyploid species with naturally occurring diploid (n=12), tetraploid (n=24) and hexaploid (n=36) forms. Information concerning the extent of the relationship among different species of Solanum nigrum complex is a prime importance for the evolutionary and taxonomic points of view. It is now well known that species hybridization has played an important role in the origin of polyploid series. Morphological, cytological and molecular characters of Indian variant tetraploid, diploid and hexaploid have been studied. An investigation of randomly amplified polymorphic DNA (RAPD) marker was made for the origin of Indian variant hexaploid S. nigrum and interrelationship with diploid and tetraploid of the complex. Out of 60 random primers 45 were used to examine 362 bands for all 3 variants. Fifteen did not amplify or showed unclear amplification across all variants. It has been concluded on the basis of RAPD data that Indian variant of tetraploid and diploid were involved in origin of hexaploid Indian variant S. nigrum. However tetraploid forms of S. nigrum play an important role in hexaploid origin.
The Eleotridae family consists of 35 genera and 150 species distributed in freshwaters/brackish waters, estuaries or shores of tropical and subtropical regions. A few species are found in the Central America and South America. Cytogenetic analyses were performed on sympatric species Dormitator maculatus (12 individuals; 9 males and 3 females) and Eleotris pisonis (5 individuals; 2 males and 3 females) collected in the lower course of the Pium River, Northeastern Brazil. Both the species have 2n=46 with striking differences for the chromosome formulas (D. maculatus, 40m-sm+6st-a and E. pisonis, 46a). The two species revealed preferentially centromeric or telomeric heterochromatic regions and absence of structural chromosome heteromorphisms between the sexes. The NORs are located on the short arm of a submetacentric pair (pair 4) in D. maculatus and in intersticial position on a medium acrocentric (pair 21) in the E. pisonis. Meiotic analyses carried out on D. maculatus and E. pisonis showed a modal value of 23 in both MI and in MII. Comparison with cytogenetic data of Mexican populations (D. maculatus, 34m-sm+12st-a; E. pisonis, 2m-sm+42st-a) indicated that the karyotypical changes among the populations from Northeastern Brazil and the Mexican coast are mainly due to pericentric inversion, although translocations, fission and fusion are involved in the karyotypic diversification of the group. The differences observed among the karyotype macrostructure of South and Central American forms suggest the existence of distinct species in these two regions.
In the present work, cytogenetic studies were performed in Corumbataia cuestae, a member of the subfamily Hypoptopomatinae (Siluriformes, Loricariidae). The specimens were collected in the Lapa Stream, a tributary of the Passa-Cinco River (Sao Paulo State, Brazil). It presented 2n=54 chromosomes with a karyotype constitution of 14M+10SM+3ST/A. Only 2 nucleolar organizing regions were observed in the terminal region of the short arm of the metacentric pair 2. Both were heteromorphic in size, while sequential analyses of the metaphases in Giemsa/silver and Giemsa/C-banding showed that the secondary constrictions correspond to NORs. The constitutive heterochromatin pattern was clearly observed in the nucleolar chromosome pair with large pericentromeric heterochromatic blocks. In the present study the authors report the hypothesis of conservation in the status of the karyotypic macrostructure of the species as compared to other species studied in the subfamily Hypoptopomatinae. Therefore, this study brings a contribution to base the phylogenetic correlations between the Corumbataia genus and other genera in the group.
Chromosome studies, in situ estimation of 4C nuclear DNA content and isoesterase profiles of vegetative propagules were carried out in dioecious Coccinia indica Wight and Arn. Somatic chromosome number 2n=24 though recorded in both sexes, a distinct heteromorphic pair of sex chromosome is found in male plants. Diploid males are heterogametic with 22+XY and females are homogametic with 22+XX. The somatic chromosomes are generally short with median and submedian constrictions except the metacentric Y chromosome which is conspicuously large. The relative size differences of chromosomes indicate a tendency towards progressive asymmetry. 4C nuclear DNA content shows marked variation in relation to sex and a positive linear relationship between the amount of the DNA and the total chromosome length is recorded. The average packing ratio (APR) of male and female plants differs which suggests a differential organisation of mitotic chromosome in relation to sex. Differences in the isoesterase pattern obtained in the vegetative reproductive structure indicate that it could also be used as an important biochemical marker for identification of sexes.
Our aim is to develop and evaluate monitoring systems using aquatic organisms to assess the genotoxicity of water. We evaluated the genotoxicity of 5 model chemical mutagens by single cell gel electrophoresis (comet assay) using goldfish primary culture cells. The cells were collected at 3 h after treatment of each mutagen. Treatments with an alkylating agent (MNNG), a DNA oxidative agent (H2O2), a DNA crosslinking agent (MMC), an RNA polymerase inhibitor (Actinomycin D), and a topoisiomerase inhibitor (VP-16) induced DNA fragmentation. All of tested chemicals induced DNA damage fragmented by dose- and time-dependently except MMC. Since the comet assay detects genotoxicity as DNA fragmentation, this result shows that the comet assay using fish cells are suitable for the monitoring of environmental genotoxicity.
Cytogenetic studies were carried out on four species of Indian snakes vizEryx johni (Family Boidae), Ptyas mucosus, Natrix stolata (Family Colubridae) and Bungarus caeruleus (Family Elapidae) collected with the help of handnet from Jammu region during the months May to Sept. 2004. Tissues, such as bone marrow and spleen were extracted and slides were prepared by air drying technique. Both Eryx johni and Ptyas mucosus exhibit 2n=34 with undifferentiated sex chromosomes which points to more closeness of Ptyas mucosus to Boidae than to other members of Colubridae. The diploid complement of Natrix stolata has 36 chromosomes (2n=36) with well differentiated sex chromosomes, while Bungarus caeruleus exhibits 2n=44 with sex chromosomes (ZW) and having submetacentric ‘Z’ and largest telocentric ‘W’. This deviation from modale number of Ophidian (2n=36) with largest ‘W’ points towards its highly advanced nature.
New records of chromosome numbers were found in Indian muntjacs (Muntiacus muntjak) and fea's muntjacs (M. feae) in Thailand. Cytogenetics of endangered wildlife species, Indian muntjacs and fea's muntjacs were examined by lymphocyte culture of whole blood. The karyotypes of 3 female Indian muntjacs indicated chromosome number of 2n=6. The X chromosome was fused to the p-arm of chromosome paired 3. The 2 male karyotypes showed chromosome number of 2n=7 and the first finding out of 2n=9. The 2n=9 might originated from breakages of 2 large metacentrics in the 2n=7 to become 2 large acrocentrics, as the 2 fragments to become the 2 large telocentrics in the 2n=9. Karyotypes of 4 female fea's muntjacs indicated chromosome number of 2n=13 and the first discovery of 2n=12 and 2n=14. The 2n=12 and 2n=13 originated from fusion of chromosome paired 7 and chromosome paired 2 in the 2n=14. The karyotypes of the 2 males revealed chromosome number of 2n=14. The X chromosome was fused to the p-arm of the acrocentric chromosome paired 1 and the Y chromosome was the small submetacentric. The variation of chromosome numbers was caused from chromosome breakages and fusions in this genus.
The present study demonstrated the cytogenetic and hematological effects of the antibiotic chloramphenicol in blood cultures of calves, at 4 days and 3 weeks after stoppage of injection with chloramphenicol by the minimal therapeutic dose (once a day for 4 successive days). The different types of chromosomal aberrations including breaks, gaps, deletions and fragments were increased in blood cultures after injection with chloramphenicol at significant levels ranging from p<0.05 to p<0.01. The total number of structural chromosomal aberrations was increased at highly significant level p<0.001 when compared with control. The frequencies of sister chromatid exchanges in blood cultures of calves after the injection with chloramphenicol were significantly increased, whereas the mitotic index was decreased at significant levels ranging from p<0.01 to p<0.001. The hematological analysis showed that there is no change in hemoglobin concentration after injection with chloramphenicol. Leucocytosis was shown only at 4 days after the stoppage of injection with chloramphenicol, whereas the lymphopenia and the neutrophilia were shown at 21 days after the stoppage of injection.
We investigated two genes that encode a homolog of the bacterial cell division site determinant MinD, PpMinD1 and PpMinD2, which were previously identified in the moss Physcomitrella patens. Southern analysis suggested that the P. patens genome does not contain minD genes other than PpMinD1 and PpMinD2. Molecular phylogenetic analysis and the results of a transient expression assay using MinD : green fluorescent protein (GFP) fusions implied that PpMinD1 and PpMinD2 are cyanobacterium-derived, closely related genes encoding chloroplast-targeted MinD proteins. Disruption of the genomic PpMinD1 or PpMinD2 locus had no detectable effects on plastid division. This implies that there is functional redundancy in the two minD genes in P. patens.
Respective fates of male and female flagella and the eyespot during fertilization of ulvophycean alga Caulerpa racemosa (Forsskål) J. Agardh var. laetevirens (Montagne) were studied using field emission scanning electron microscopy (FE-SEM). FE-SEM allowed visualization of the eyespot of the biflagellate gamete. The female gamete has one eyespot on a posterior position of the cell body; the male gamete does not. The female gamete eyespot was oriented to the direction of the plane of the flagellar beat. The female gamete is larger than the male one and has the only eyespot. For those reasons, the author followed the fate of the flagella and eyespot during fertilization. When both gametes were mixed, the initial cytoplasmic contact and cell fusion between them usually took place at the anterior end slightly below the flagellar base. In most mating pairs, the female gamete fuses at the left side of the eyespot and male gamete at a cell surface that is perpendicular to the plane of the flagellar beat. As fusion proceeds, the gamete pair is transformed into a quadriflagellate planozygote in which two flagella each from the male and female gametes point in nearly the same direction. In particular, the no. 2 flagellum of the female gamete and one male flagellum were directed to the eyespot. These observations indicated that cell fusion at the particular area of the gamete is important for proper arrangement of the flagella and eyespot in the planozygote.
Chromosomes are super-molecules consisting of DNA, histone and chromatin proteins, which specifically appear within a cell at the cell division. We analyzed barley chromosomes by atomic force microscopy (AFM) to elucidate its structural basis. Mitotic chromosomes were taken from root tips of barley (Hordeum vulgare L., cv. Minorimugi) using the EMA (enzymatic maceration and air-drying) method after synchronization of cell cycle. Both the air-dried or critical point dried specimens were observed in air by a dynamic force mode. This observation technique enables to obtain three-dimensional image data on the surface structure of barley chromosomes at high resolution without any metal coating. The details of the higher order chromosomal structure such as chromatin fibers were clarified with the biological significance. Acidic treatment (e.g., acetic acid treatment) for removing proteins was useful to obtain clear images of basic chromosomal structure. Thus, it is concluded that the AFM has a great potential for investigation of molecular structures of chromosomes.
The chromosomes of 4 species of grasshopper in the genus Oxya were analyzed by conventional and five differential-staining methods. All 4 species had a chromosome complement of 2n=22+XX(female)/XO(male), with very similar karyotypes. Both O. hyla intricata and O. japonica japonica had acrocentric chromosomes with minute short arms, while the chromosomes of O. chinensis formosana and O. yezoensis were almost all telocentric. In all 4 species, a secondary constriction (SC) was detected at a proximal site in chromosome 8, which had the same staining properties (positive for C- and CMA-banding; negative for G- and QM-banding) in all 4 species. Our C-banding analysis revealed that the short arms of O. hylaintricata and O. japonica japonica consisted of C-heterochromatin. The 4 species yielded species-specific patterns of C-bands, and there appeared to be a close relationship between O. chinensis formosana and O. yezoensis, as suggested by the polymorphism of the distal C-bands of chromosome 2. In all 4 species of Oxya, Ag-NORs were detected on the centromeric regions of all the chromosomes, but not detected on the SC of chromosome 8. The karyosystematic relationships among the 4 species are discussed on the basis of the results of differential staining.