The present study was carried out to evaluate the cytogenetic effect of manganese sulfate (MnSO4) in cultured mouse spleen cells and the possible protective effect of folic acid (FA) and/or vitamin B12 (VB12) on cell cultures treated with MnSO4. Cultured mouse spleen cells were treated with MnSO4 at 4 concentrations (10-6, 5×10-6, 10-5, 10-4). FA at 10-5, 5×10-5 and 10-4M, and VB12 at 5×10-6, 10-5 and 5×10-5 M were used for testing the protective effect on chromosome damage induced by MnSO4. The highest dose (10-4 M) of MnSO4 were treated simultaneously with FA and/or VB12. The cultures were set up for 24 h. The results indicate that MnSO4 alone induced a concentration-related increase in the percentage of chromosome aberrations. Both FA and VB12 reduced the percentage of aberrant cells in a significant (p<0.01) and dose-dependent manner. However, FA combined with VB12 caused a highest percentage of reduction (62.20-71.94%). Under the present experimental conditions, FA and VB12 are capable of reducing the cytogenetic damage induced by MnSO4 and appear to be an antimutagenic agent.
The meiotic behavior and somatic chromosomic number of 4 populations belonging to Minthostachys mollis (Kunth.) Griseb. species were determined. This is the first study on these aspects not only for this species but also for the entire Minthostachys genus. The most frequent meiotic irregularities observed were univalents, laggards and triads; whereas cytomixis and bridges were observed only in 2 populations. Besides the occurrence of triads, the presence of hexads and dyads were also seen. With respect to the somatic chromosomic number, this study reveals the presence of 2n=42 chromosomes for the P1, P2 and P3 populations and 2n=24 chromosomes for the P4 population.
Cytotoxic effects of castor (Ricinus communis L.) seed extract on Allium sativum root tip cells were investigated. The results obtained showed that the seed extract of R. communis L. induced various types of cyto/chromotoxic effects which included fragments, ring chromosomes, C-mitosis, end to end attachment of the chromosomes at metaphase, chromatin bridges, laggards, unequal distribution of chromosomes and multipolar cells. Nuclear cleavage and disintegration, inhibition of cytokinesis, doubling of chromosome numbers, binucleate cells and binary fission of the nucleus were also observed. The most significant observations were the denaturation of chromatin fibre and somatic reduction that were encountered following treatment with 50 and 100% concentrations of the seed extract. The investigation also revealed that the rate of cell division was affected by castor seed extract. The rate of cell division (measured in terms of active mitotic index) decreased with the increase in concentration of the castor seed extract. It is therefore concluded that the castor seed extract not only upset the normal rate of cell division but also induced various structural and numerical chromosomal aberrations that may lead to mutation in the affected organism.
Karyotype analyses of saffron, Crocus sativus L., was made using improved routine and C-banding techniques on metaphase plates in root tip cells of 2 accessions from Republic of Azerbaijan and Iran. In the routine technique fixative of Lewitsky and aceto-iron-hematoxylin stain were used. It was established that metaphase chromosomes can be arranged according to their size and morphological features in 8 triplets ranging in size from 11.58±0.13 μm (triplet 1) to 4.57±0.05 μm (triplet 8). Triplets 1 and 2 include subacrocentric, triplets 3, 4 and 8 metacentric and triplets 6 and 7 submetacentric chromosomes. Three chromosomes in each triplet, as a rule, are similar although in some triplets one of them is infrequently distinguishable from the 2 others. Triplet 5 shows an extreme difference so that it always contains 2 kinds of chromosomes: chromosome 5(1) and chromosomes 5(2, 3). Chromosome 5(1) is metacentric (r=1.40) and 6.04±0.13 μm in length, but chromosomes 5(2, 3) are subacrocentric (r=3.49) and noticeably smaller (5.41±0.09 μm). Application of the C-banding technique revealed heterochromatin segments: the sharpest, sharp and week. The sharpest heterochromatin was on telomere of the short arm of chromosome type (triplet) 3 and on proximal part of the long arm of chromosome type 1; a sharp heterochromatin on telomere of the short arms of chromosome types 1, 4 and on the satellites, and a weak heterochromatin on a centromeric region all of 24 chromosomes. Chromosome type 5(1) had a heterochromatin that was a little stronger on the centromeric and, considerably weaker on telomeric regions comparing to those of chromosome type 4. Accessions of saffron from Republic of Azerbaijan and Iran were not significantly distinguishable in karyotype structure. The species C. sativus in its places of cultivation is obviously a clone of one triploid plant originated spontaneously in the nature through crossing between 2 closely related species with participation of n and 2n gametes. Results from statistic analysis and appropriate photographic evidences are provided.
The Diplopoda have received little attention from cytogeneticists owing mostly to technical difficulties in obtaining mitotic chromosomes, restricting the studies to meiosis and eventual spermatogonial metaphases, which limits the use of modern cytogenetical techniques. A literature search shows that only about 0.1% of all known species have been cytogenetically studied. There are 80, 000 species estimated for this group, making it the 3rd. larger class in Arthropoda, after Insecta and Arachnida. The diploid chromosomal number in diplopods varies from 2n=8 to 2n=30 and the sex determination mechanism commonly found is XY/XX. In meiotic prophase, the “bouquet formation” and the diffuse state in pachytene are typical events. The few works performed on Brazilian fauna add up to 16 species, out of an estimated number of 2000 to 3000 species. The present review reports all the species of diplopods that have been cytogenetically studied so far, each with its chromosome number and sex determination system.
Chromosome studies were carried out on 5 Argentinian species of Stemodia. First chromosome counts are presented for S. ericifolia (2n=22), S. lanceolata (2n=22), S. stricta (2n=44) and S. hyptoides (2n=66), while the number 2n=22 of S. verticillata is confirmed. These numbers constitute the first reports for South American species of Stemodia. In addition, the karyograms of S. lanceolata and S. verticillata are the first descriptions for the genus. Diploid species showed regular meiotic behaviour and pollen viability was high in all the accessions analysed. These results suggest that 2 different mechanisms would be implicated in chromosome diversification of Stemodia. The first one implicates variation in genome size with karyotype formulae conservation and the second, polyploidy. Chromosome data provided here are discussed in relation to growth habit, morphological characters and taxonomic position of the species.
The cells of secretory region of the salivary glands of Pachycondyla (=Neoponera) villosa at the time of enzyme production presents the basal cellular membranes profusely folded and the intercellular junctional membranes present a few enlarged spaces. The rough endoplasmic reticulum and the Golgi bodies shift from being flat and small vesicular cisternae to enlarged vesicular cisternae according to the cell physiological state and characterize an asychronic cell cycle. Enzymes are released into the lumen by microapocrine secretion. The stage of silk production is detected after a behavioral act, when the nurse worker separates the mature larva. At this time, the salivary gland cells present only one physiological state (synchronized secretory cycle): this state was characterized by basal cellular membrane poorly folded, intercellular junctions presenting some small spaces, rough endoplasmic reticulum compounded by flat cistenae, enlarged Golgi bodies with fibrous material inside and a few secretory vesicles containing silk, which undergo exocytosis. The silk in the lumen shows a forms: tactoid and flocculent material.
The genus Diabrotica is characterized by having a great uniformity of karyotype in respect to the chromosome number and morphology, with the exception of Diabrotica speciosa. The diploid chromosome number, the morphology of chromosomes, the type of sex determination, the pattern of constitutive heterochromatin distribution and the chromosomes bearing the nucleolus organizer regions (NORs) were studied in specimens from 3 different Brazilian populations of D. speciosa. The analysis of mitotic cells revealed 2n=21 in the males and 2n=22 in the females. All the chromosomes of the complement were metacentric and the type of sex determination was XO/XX. Additionally, mitotic metaphases of 1 female from the Ponta Grossa population showed the occurrence of heteromorphic homologous chromosomes in pair 9. The male meiocytes showed 10 bivalents and a univalent X chromosomes. One or 2 chiasmata were found per bivalent in diplotene. The constitutive heterochromatin was found in the centromeric region of all the autosomes and in both arms of the X chromosome. Besides, some autosomes of 1 specimen from the Ponta Grossa population were heteromorphic for C bands. NORs were found the telomeric region of pair 9 in all the individuals of the populations.
Cytogenetic studies were performed on 4 Anostomidae species from the Sapucaí river, Minas Gerais, Brazil. Leporinus friderici, L. octofasciatus, L. striatus and Schizodon nasutus. Nuclear DNA content determination in 3 species revealed that L. striatus had a higher nuclear DNA content than S. nasutus and L. octofasciatus, respectively. Chromosome studies involving Giemsa, C-banding and Chromomycin A3 staining showed that the chromosome number and morphology, of these 4 species was very similar. On the other hand, some differences regarding number of chromosomes with NORs in S. nasutus and some particularities of the pattern of heterochromatin distribution in L. friderici were observed. These data indicate the occurrence of some diversification of heterochromatin size and position and Ag-NORs reorganization of the karyotypes, as observed in some other species and populations of the family Anostomidae.
Three new tetraploid secalotricum forms with genomes of Triticum and S. cereale were studied. Using differential staining of the chromosomes it was established that pairs of 1B, 2B, 3B, 4A, 5A, 6A, 7B wheat and 14 rye chromosomes were observed. In diakinesis were counted 14 closed ring bivalents. The study with Giemsa C-banding in metaphase I showed that the rod bivalents and the univalents belong to the rye genome. Those with 2 telomeric heterochromatin blocks were prevailent. The tetraploid secalotricums were characterized by a considerable cytological stability, as only 15.10 to 17.68% of the tetrads had micronuclei.
The post-pharyngeal gland of normal and starvation ants was studied under TEM. This study showed an orgin of lipids droplets from mitochondria (named derivate mitochondria) in the normal ants and the lipids absence or reduction, in fasting ants.
Chromosomal aberrations (CA) and micronuclei polychromatic erythrocyte (MNPEC) from bone marrow cells of mice, and electrophoresis of B-esterase, lactate dehydrogenase and malate dehydrogenase from blood serum of mice were taken as an indication of the effects of electric field of strength 6 kV/m and frequency 50 Hz on the cytogenetic and isozyme electrophoresis. The chromosomal aberrations (CA) and micronuclei polychromatic erythrocytes (MNPEC) from bone marrow cells of mice were investigated after 30, 45 and 60 d of exposure to the electric, 4 mice were used for each period. The significant frequency of the chromosomal aberrations and MNPEC increased with increasing the time of exposure to the electric field. After switching off the power supply of the electric field, for a period late 30 d from post-exposure for 60 d. A progressive decrease in the chromosomal aberrations and MNPEC was noticed, but the percent of aberrations was still higher than that of the control. In the mean time, the mitotic index (MI) was also decreased when compared with the control. Also, the isozyme electrophoresis such as B-esterase and lactate dehydrogenase (Ldh) were slightly affected whereas malate dehydrogenase (Mdh) was not affected by ELFEF.
Chlorophyllin (Chl), a cupric salt of the chlorophyll, was used at concentrations of 12.5, 25, 50μg/ml in culture medium (Chl 12.5, Chl25, Chl150, respectively), in the presence or absence of mitomycin-C MMC (220×10-6M), in V79 cell culture, to assess the antimutagenic effects in the micronucleus assay on binucleate cells. Chlorophyllin was used in association with MMC in simultaneous treatments, pre and post treatments and simultaneous treatments after chlorophyllin had been pre-incubated with MMC for 1h. The results showed that chlorophyllin per se did not induce micronucleus formation at any of the concentrations assessed. The simultaneous treatment reduced significantly the micronucleus frequency at concentrations of 12.5 and 25μg, in 37.93 and 35.63%, respectively. At pre and post treatments, all the concentrations produced significant reductions: 45.98 Chl12.5), 43.68 (Chl25) and 28.73% (Chl50) in the pre treatment and of 36.78% (Chl 12.5), 51.72% (Chl25) and 37.93% (Chl50) in the post treatment. The same was observed in the simultaneous treatment after pre-incubation, where reduction of 48.27% (Chl 12.5), 57.47% (Chl25) and 58.62% (Chl50) were observed. These results indicated that chlorophyllin was not mutagenic in the system used and pointed to significant antimutagenic activity of the chlorophyllin. The data obtained in the simultaneous treatments suggested desmutagenic action whereas the pre and post treatments suggested bioantimutagenic activity of chlorophyllin in V79 cells.
Chromosome analyses were carried out on 3 species of fish, Moenkhausia sanctaefilomenae, Moenkhausia intermedia and Hemigrammus marginatus (Tetragonopterinae) from the upper Paraná River floodplain (PR, Brazil). Species showed diploid number 2n=50 chromosomes, with different chromosome formulae. Karyotype of M. sanctaefilomenae was composed of 12M+36SM+2ST, while M. intermedia had 16M+34SM, with FN=100 for both species. Diploid numbers and chromosome formulae presented a predominance of 2-arm chromosomes, similar to that of other species of the genus. Since the chromosome formulae of H. marginatus is 10M+34SM+6A (FN=94), it differed from the previous data on this species. NOR studies for the 3 species revealed a simple system, obtained by silver nitrate staining and CMA3. Whereas M. sanctaefilomenae presented strong heterochromatic blocks in the interstitial and centromeric regions of the chromosomes, heterochromatin of the other 2 species was mainly located in the NOR bearing chromosomes. Evolutionary and cytotaxonomic aspects of these genera are discussed.