Three isozyme systems viz. esterase, peroxidase and amylase were assayed electrophoretically from extracts of leaf tissues of some elite genotypes of India to unravel their genetic relationship. Twenty five isozyme phenotypes were resolved in the 9 genotypes; 8 in esterase (EST), 12 in peroxidase (POX) and 5 in amylase (AMY). The genotypes could be distinguished on the basis of polymorphic isozyme spectra and multimeric isozyme profiles. The most polymorphic isoenzyme system was peroxidase (POX), which provided a discriminatory tool for evaluating and characterizing genotypes. The banding similarly index based on the number of polymorphic bands common between each genotype pair, ranged from 0.38 to 0.89. The genotypes were clustered in 2 distinct groups having 3 and 6 genotypes each by subjecting the genetic dissimilarity between them to UPGMA (Unweighted Pair Group Mean Analysis) statistical treatment and bootstrap analysis. The consistency Index of 8 different nodes present in phenogram representing percentage useable isozyme loci per node showed the node 8 to be the most important and consistent node followed by the node 6. Some esterase and peroxidase isozyme phenotypes were specific to the genotypes and were found to be suitable for cultivar identification.
The two taxa Plantago major ssp. major and ssp. intermedia from different geographical regions were investigated karyologically. The separation of the two taxa depends mainly on seed number and size. The average karyotypic configuration for each population was used to contrast ideograms between populations from ssp. major and ssp. intermedia. The study revealed that the two taxa have distinct cytotypes which are somewhat correlated with seed number as an indication of taxonomic identity. The variation between two taxa is expressed by two main cytological groups based on the total form percentage (TF %) which measures the symmetry of the chromosomes over the whole karyotype. The study also revealed that the evolution of the P. major group may be in part due to chromosomal rearrangement. The study concluded that most major karyotypes are more symmetrical than those of intermedia, which may be an indication that intermedia is the derived type.
The tribe Meliponini comprises several hundred species of stingless bees which are major pollinators of many tree species. In the present work we studied two Partamona species: Partamona helleri and Partamona seridoensis. Both species presented similar karyotypes with 2n=34 chromosomes for females, pericentromeric heterochromatic blocks and terminal GC rich heterochromatic segments in chromosome pairs 2, 9, 10 and 15, as shown by sequential C banding-DA/CMA3 staining. The heterochromatin is heterogeneous: pericentromeric and the terminal blocks behave quite differently. FISH with 18S rDNA probe showed that NORs were in terminal blocks. In addition, B chromosomes were observed in P. helleri. The results of the different treatments employed such as C banding and fluorochrome staining led us to believe that their origin was not due to non-disjunction of A genome chromosomes. Supernumerary pericentromeric heterochromatin and the non-homologous portion of a heteromorphic pair behaved in a similar fashion, indicating that may be originated by fission. The FISH assay showed, however that there was no sequence correspondence between these segments.
Untreated wastes (0.125, 0.25, 0.50 & 1.0%) from silk industries induced both gross and individual types of chromosome abnormalities in bone marrow cells of mice. The frequency of the abnormalities increased with the increase of doses. Polyploidy and aneuploidy were found to be common among the gross, while chromatid breaks, gaps acentric fragments were most common among the individual type. The waste interferred the internal milieu of cells leading to grosstype of demages, while certain ions and reactive radicals formed during their metabolism induced the breakage in the chromosomes.
The ability of pure insecticide “Monocrotophos” to induce chromosomal abnormalities in mouse somatic and germ cells was investigated. Male swiss mice were treated by gavage with the doses 0.05, 0.1 and 0.2 mg/kg−1 body wt. Samples were taken 6, 24 and 48 h after treatment. The percentage of chromosomal aberrations increased by increasing the concentrations of the insecticide and reached its maximum 24 h following oral treatment in both somatic and germ cells. In splenic cells, it reached 24.8±0.73 and 17.8±0.86 (p<0.01) 24 h after treatment with highest and lowest doses of the insecticide respectively compared with 26.2±1.02 (p<0.01) 24 h after i.p. injection with Mitomycin C at 1 mg/kg−1 body wt. In primary spermatocytes at diakinesis metaphase I of meiosis, the percentage of chromosomal aberrations reached 21±0.71 (p<0.01) 24 h after treatment with the highest dose of Monocrotophos. The frequency of sister chromatid exchanges (SCE's) in mouse bone-marrow cells was dose dependent and statistically significant after treatment with all doses of Monocrotophos. The insecticide significantly increased chromosomal aberrations in mouse spleen, bone marrow and spermatocyte cells. Royal jell decreased the percentage of the induced chromosomal aberrations in somatic and germ cells after treated by gavage.
The calli of a Sorghum bicolor×Saccharum officinarum hybrid was irradiated at different doses of gamma radiation to induce normal flowering and panicle emergence in this hybrid. Fifty one somaclones were regenerated from the irradiated calli and field planted during May, 2004. One of the somaclones (SSS-03/152) flowered during November, 2004 producing an inflorescence, similar to that of sugarcane. This somaclone was found to be pollen sterile, but had apparently normal female reproductive structures.
Natural products from flora have been largely used in popular medicine for centuries. The development of tests to measure mutagenic activity of chemicals has been helpful to increase security and safety of different compounds, including natural products. The present study was carried out to evaluate the mutagenic effects of a water-ethanolic crude extract obtained from Pothomophe umbellata aerial parts on Rattus norvegicus cells in vivo, using the comet (SCGE) and micronucleus (MN) assay. Animals were treated orally with three different concentrations of the extract (500, 1000 and 1500 mg/ kg) and sacrificed 24 hours after treatments. The results have shown that the extract of P. umbellata did not induce statistically significant increases in the average numbers of DNA damage in hepatic cells and MN in bone marrow cells. However, a significant increase of DNA damage in peripheral blood cells has been noticed.
Cytological studies on 45 accessions of Saccharum spontaneum collected from the state of Kerala, India showed the predominance of 2n=64 types in the state. Barring one clone IND99-902 which recorded 2n=72, the chromosome number of rest of the clones was found to be 2n=64, which is the most common cytotype in the country. It is likely that the 2n=72 form has originated from hybridization between 2n=64 and 80 types, both of which have been reported from the region. The karyotype of 5 of the clones studied conformed to 1a, 2a or 2b type of Stebbins. Satellite chromosomes were present in 4 clones. Meiosis was largely regular in all the 2n=64 types with predominant bivalent formation. Univalents were few in the range of 0 to 5.6. The clone IND99-902 (2n=72) showed meiotic abnormalities in the form of univalents, laggards and bridges. The 2n=64 types showed high pollen fertility while the 2n=72 type was found to be nearly pollen sterile.
The frequency and distribution of fragile sites by different concentration of distamycin-A were studied in the blood cultures of buffalo lymphocyte. The percentage of total aberrant cells, total breaks, total gaps, total structure abnormalities, deletion and polyploid were detected in the treated and control cultures. The results revealed that the treated cultures showed increases in the chromosomal abnormalities particularly in breaks and gaps at 50 and 100 μg/ml of distamycin-A concentrations compared with control cultures. Metaphases affected with chromosomal aberrations were destained and reexamined after G-banding to allow the identification of fragile sites involved. The fragile sites were identified as a site of non-staining gaps or breaks at specific points on chromosomes and their frequencies more than 3% per individual. The distamycin-A inducible fragile sites expressed as 1q22, 1q35, 4q26, 4q35, 6q36 and Xq22. In conclusion, the fragile sites are unique chromosomal regions and hot spots for establish break points maps and integration of foreign genomes.
Karyomorphological analysis of seven Gossypium species belonging to ‘A’ (G. arboreum, G. herbaceum), ‘D’ (G. aridum, G. armourianum, G. davidsonii), ‘AD’ (G. hirsutum, G. barbadense) genome was carried out. All the species invariably shows the basic chromosome number as x=13. The chromosome size ranged from 1.1 to 4.7 μm. G. aridum had the smaller mean chromosome length (1.15 μm) while G. barbadense had the larger chromosome (4.7 μm). Karyotypes were of symmetrical type possessing long and short chromosomes in equal proportions. The satellite chromosomes were located in the long arm of one or two metacentric pair. The species varied with regards to number of SAT chromosomes and chromosome carrying secondary constrictions. Cluster analysis was done to group the species. It shows that the cotton species studied falls in to three distinct clusters. Results also revealed that the popular, cultivated American cotton G. hirsutum, and the Egyptian cotton G. barbadense might have originated from the crosses between the Asiatic cotton G. arboreum, G. herbaceum (‘A’ genome) and the American wild cotton G. aridum, G. armourianum, G. davidsonii (‘D’ genome). The present finding clearly indicates the genomic differences within the diploid species and between the diploid–tetraploid species of cotton can be utilised in hybridization programmes. Crossing of the species placed in distant clusters are suggested.
Four species of Eleusine viz. E. intermedia, E. floccifolia, E. indica and E. tristachya are wild diploid taxa (2n=2x=18) and are presumed to have contributed to the evolution of finger millet, E. coracana, the amphidiploid with AABB genome (2n=2x=36) and an important minor millet grown in Africa and South Asia. E. indica is known to have contributed the A genome to E. coracana, while the information regarding the other genome donor species is not forthcoming. The present investigations were undertaken to clearly understand the genome homology of 3 species viz. E. intermedia, E. floccifolia and E. tristachyavis-à-vis the A genome of E. indica and to analyze the interspecific relationship among these diploid species and their possible contribution to the evolution of E. coracana. Interspecific F1 hybrids of E. intermedia×E. indica, E. intermedia×E. floccifolia and E. tristachya×E. intermedia were produced and studied for morphological and cytological details. The experimental data revealed a high degree of homology at the interspecific level among all 4 species resulting in high frequency of bivalents and a very low frequency of univalents and multivalents. Inspite of good chromosome pairing and bivalent formation, a significant reduction in pollen stainability (8–32%) has been recorded in the F1 hybrids. The data obtained on chromosome associations at diakinesis/ metaphase I of meiosis suggest that these diploid species form a close genetic assemblage within the genus Eleusine. Various factors affecting the pollen stainability and seed fertility are discussed in the light of available information on the subject.
The karyotypes of 4 Haworthia species viz.H. papillosa Haw., H. fasciata Haw., H. limifolia Marloth and H. reinwardtii Haw. were compared after differential staining with orcein, CMA and DAPI. In H. papillosa and H. fasciata 2n=14 chromosomes were found. H. limifolia and H. reinwardtii possessed 2n=21 and 2n=35 chromosomes, respectively. These 4 species possessed distinct bimodal karyotypes. Two satellites were found one in each on the long arm of 2 large chromosomes of these 4 species. The staining property of satellites was different in each species. In H. papillosa, satellites were found in orcein and CMA-staining, negative satellites were found in DAPI-staining. H. fasciata showed satellites in CMA and DAPI, whereas no satellite was found in orcein staining. Two CMA-positive and one DAPI-negative satellites were found in H. limifolia, but none in orcein staining. In H. reinwardtii, satellites were found in orcein staining and not in CMA- and DAPI-staining. No DAPI-positive or negative band was found on the chromosomes in these 4 species. H. papillosa possessed an interstitial stable CMA-positive band on the long arm of a chromosome in pair I. This kind of banded chromosome was absent in other 3 species and thus can be used as a marker. The CMA-banded karyotype of H. limifolia showed a probable occurrence of paracentric inversion and deletion. It also indicated the presence of different genomes with partial homology. Therefore, H. limifolia seems to be a segmental allotriploid. 2n chromosome number together with orcein, CMA and DAPI karyotypes suggests H. reinwardtii as an autopentaploid.
The karyotypes of 3 varieties in Cicer arietinum L. viz. BS-6, BS-7 and BS-8 were compared after differential staining with orcein, CMA and DAPI. The total chromatin length of BS-6 and BS-8 were 66.20 μm and 61.30 μm whereas 86.00 μm had in BS-7. The centromeric formulae of BS-6 was 12m+4sm, that of BS-7 was 14m+2sm and in BS-8 was 11m+5sm. Six CMA-positive bands were found in BS-6. Variety BS-7 and BS-8 possessed 4 CMA-positive bands in each. 20% GC- rich repeats was found in BS-6. Both BS-7 and BS-8 had 11.70% of GC-rich repeats. One CMA-negative band was found in BS-8 only. Three DAPI- negative bands were found in BS-6 at the same location where the CMA positive bands were present. Reversible banding indicates the presence of GC-rich repeats at those positions. These 3 chromosomes of BS-6 could easily be identified with reversible banding properties. No DAPI-negative band was found in BS-7 and BS-8. One DAPI-positive band was found in 2 chromosomes of BS-8. These chromosomes may consider as DAPI-positive marker. Two satellited chromosomes were found in BS-7 whereas 1 satellited chromosome was found in each BS-6 and BS-8. The satellite of BS-6 showed CMA-positive and DAPI-negative features. The satellites of BS-7 were CMA-positive and slightly DAPI-negative. The satellite of BS-8 showed CMA- and DAPI-positive nature. The different features of the satellites seem to characterize these 3 varieties.
Two genera, Brassica and sinapis, belong to the family Cruciferae (Brassicaceae). It had been suggested that they had have 1 ancestor and 2 different lineages. Detailed cytogenetical study had been carried out on 6 species belonging to them. These are: B. nigra, B. rapa (=campestris) and B. tournefortii from genus Brassica and S. alba, S. allionii and S. turgida from genus Sinapis. Data obtained by the present study support this suggestion. Karyomorphological analysis for 4 species reveals that B. nigra is the most primitive and it was similar to S. turgida and S. allionii. Also meiotic analysis and electrophoretic seed protein profiles confirm the karyomorphological results. Moreover, seed protein electrophoresis indicates that these 2 genera had a characteristic protein composition which is of taxonomic importance. So, the present resulted information could be considered a reliable data which aid in reevaluation the evolutionary relationships of the 2 genera. Moreover, these present data prove that they are highly paraphylogeny.
Meiotic analysis documented variation in chromosome number in Ocimum basilicum L. (family: Lamiaceae) in the form of 2n=72 chromosomes in O. basilicum var. citriodorum (lemon basil) and 2n=52 chromosomes (a new number in Ocimum) in variety crispum. Persistent presence of secondary association of chromosomes in 87.88% and 69.39% metaphase I cells of var. citriodorum and var. crispum respectively suggested secondary polyploid nature of the species. Statistical analysis of cytological data revealed x=12 as basic chromosome numbers for the varieties studied and polyploidy as well as aneuploidy might have been operative at different levels to give variable chromosome numbers within O. basilicum.
Ribosomal RNA (5S and 45S) genes were determined simultaneously by fluorescence in situ hybridization (FISH) in the crucifer Orychophragmus violaceus. It carried twenty-two 5S and eight 45S gene sites. All rDNA sites were at the terminal parts of chromosomes and all eight 45S rDNA sites were colocalized together with 5S rDNA sites with the latter ones being more proximal. Double 5S rDNA sites—two sites of different fluorescent intensities on one chromosome arm separated by a short distance—were found on terminal parts of four chromosomes, with the distal one being stronger than the proximal one. No chromosomes with double 5S rDNA sites carried 45S rDNA sites. The implications of the relative order and distribution of both rDNA sites for the genome structure of the species and the identification of its individual chromosomes in wide hybrids with other species were discussed.