Karyology of the 6 Silene species from Turkey was investigated. Diploid chromosome numbers and the basic chromosome number of the studied taxa were obtained as 2n=24 and x=12 respectively. The karyotype analysis of S. viscosa, S. eremitica, S. skorpilii and S. confertiflora were carried out for the first time. Also the chromosome numbers of S. eremitica and S. confertiflora were determined for the first time. The largest chromosomes were observed in S. otites and the smallest ones were observed in S. viscosa. S. otites shows the highest A1 index. S. skorpilii represents the highest interchromosomal asymmetry coefficient (A2). The karyologic results of the study and the analysis of chromosomal morphology of each taxon were shown as tables.
The seeds of 2 varieties of common Sunflower (Helianthus annuus L.) viz:USH-430 and KL-675 were treated to estimate the mutagenicity of both gamma-rays, sodium azide alone and in combination with a view to generate morphological macro-mutations and screen and ascertain the chromosomal aberrations followed by reduction of pollen fertility with increased doses. An attempt was made to know the genetic basis of the chromosomal aberrations. Such aberrations are a source of changes in the pattern of gene regulation at the time of differentiation leading to the formation of cultivars.
The uzifly, Exorista sorbillans (=E. bombycis) a tachinid endoparasitoid of silkworm, Bombyx mori L., known to cause considerable damage to the silk industry. Earlier studies on various aspects of the uzifly indicated for possible presence of a number of cryptic species. Though the fly entered into South India 25 years ago, the basis for the existence of cryptic species was not known. To ascertain whether the genome of this parasitoid is differentiating into discrete gene pools in contrasting eco and geo-climatic conditions, an attempt has been made in the present study the molecular profiling of 8 populations (Chitoor, Kuppam, Erode, Bangarapete, Sira, Mandya, Chitradurga, and Kanakapura) from south India with 16 RAPD primers and also to explore the possibility of its endosymbiont Wolbachia as a causative agent as it known to cause cytoplasmic incompatibility in its host uzifly. The hierarchical clustering done on the basis of RAPD data and the Euclidean distance matrix put Chitradurga populations at the maximum distance from other south Indian populations studied and reveals the occurrence of spectacular region-wise pairing with separate clusters. Further, when we have crossed within and between selected populations for the Wolbachia induced reproductive isolation, the results showed the lower level (28–32%) of reproductive isolation within and between populations. The RAPD and crossing data clearly indicates the micro-level divergence in the uzifly, E. sorbillans. The significance of this study with a tachinid fly pest is discussed in the context of understanding the diversification of uzifly and also establishing this pest as a relevant biological material for studying microevolution in nature.
Cytogenetical analysis of the interspecific hybrid between M. esculenta (cassava) and M. oligantha revealed a fair chromosome pairing and a high viability of pollen grain. Studying ovule structure by clearing method showed multiembryony in 2.7% of ovules studied. Doubling chromosome number resulted in an increase of multiembryony up to 18% and reduction of pollen viability. Multivalent formation was observed too. In anatomical stem study of diploid and tetraploid hybrids it was noted larger number of vascular bundles in tetraploid type.
Karyotype analysis in 9 species of Jute (Corchorus, Family. Tiliaceae) is performed through Image Analyzing System with the objective to get accurate numerical data from metaphase plate microphotographs for ascertaining interrelationship among/between the species following clustering analysis. Karyotypes revealed (2n=14) 3 (C. fascicularis), 2 (C. capsularis, C. olitorius, C. aestuans, C. pseudocapsularis, C. pseudoolitorius) and 1 (C. tridens, C. trilocularis and C. urticaefolius) morphologically distinct chromosome types in the genus with prevalence of median chromosomes, mostly graded (evidenced from relative chromosome length) and symmetrics. C. fascicularis also showed 2n=28 (11.54%) chromosomes. Absolute chromosome length among the species varied from 1.37 μm to 3.50 μm. Haploid chromatin length (11.97 μm–17.72 μm) ranged significantly (p<0.001) among the species. An identification key of the species has been formulated on the basis of karyomorphological data. A dendrogram was constructed and it showed close relationship between C. olitorius and C. aestuans and among C. pseudoolitorius, C. trilocularis and C. urticaefolius. A complex evolution in the genus was suggested.
Within the genus Prochilodus, the species Prochilodus lineatus is certainly the most studied one from a cytogenetic point of view. In this study, a cytogenetic characterization of specimens of P. lineatus from Mogi-Guaçu River was performed in the period from 2003 to 2007, through utilization of cytogenetic markers, such as Giemsa, Ag-NOR, C-banding and cytogenetical-molecular markers (FISH) to detect both 5S and 18S ribosomal genes. All analyzed individuals presented 2n=54 meta/submetacentric chromosomes, besides bearing up to 7 supernumerary microchromosomes. Polymorphic NORs were detected on a single chromosomal pair. The constitutive heterochromatin was distributed at centromeric region of all chromosomes in the A complement, while the microchromosomes were totally heterochromatic. A syntenic distribution of 5S and 18S ribosomal genes was detected, comprising the NOR-bearing chromosomal pair. No additional ribosomal clusters in other chromosomes were observed. Although the karyotype features are commonly conserved within the genus Prochilodus, the few differences on the distribution of both ribosomal genes and heterochromatin when compared to specimens of P. lineatus from other localities can be associated to the evolutionary changes that these repetitive sequences have undergone through the years.
The 7 accessions of Carthamus tinctorius from different locations were analyzed in detail for establishing the chromosome and karyotype polymorphism. All 12 pachytene chromosomes were clearly identified on the basis of length, arm ratio, centromeric index, symmetry index, total chromatin length and Percent chromomere per chromosome. The karyotype and heterochromatin distribution patterns reported in this study provide a foundation toward cytological characterization of the Carthamus genome. The chromosome size ranges between 546.53 μm to 933.53 μm. Variability within the individual chromosomes with respect to the size, shape and position of the centromere was found to be well marked. Chromosomes were arranged from 1 to 12 following a descending order of length. At pachytene, the pollen mother cells have 12 bivalents and prominent nucleolus. The accessions exhibited significant variability in their pachytene chromosome characteristics.
Astyanax fasciatus from Parapanema River basin was studied with respect to the karyotype structure, nucleolar organizer regions, 18S and 5S rRNA genes and C-banding pattern. The specimens presented 2n=46 chromosomes, with multiple NORs detected by silver nitrate staining (Ag-NORs) and confirmed by fluorescence in situ hybridization (FISH). Ten 18S rDNA sites were found, located in the telomeric regions of 4 distinct chromosome pairs, with bitelomeric locations in one of them. The 5S rDNA sites were detected in the interstitial regions of 4 chromosomes, 2 metacentric and 2 acrocentric ones. The C-positive heterochromatin was located in the telomeric regions of some submetacentric, subtelocentric and acrocentric chromosomes. Variations in the karyotypic structure, C-positive heterochromatin pattern and location 18S rDNA sites are discussed.
Cytological and molecular studies were performed on 10 Hordeum species of Iran. The species studied showed the occurrence of 2n=2x=14, 2n=4x=28 and 2n=6x=42. They formed mainly bivalents in metaphase with normal chromosomes segregation during anaphase and telophase stages, except in few cases of laggard chromosomes formation and chromosome stickiness observed in H. bulbosum. H. bulbosum and H. leporinum showed 0–2 B-chromosomes which were smaller than A-chromosomes and did not pair with them out of 20 RAPD primers used 11 primers produced 18 reproducible polymorphic bands. Specific bands were observed in some of the species or populations while, some bands occurred in all the species except one showing the species genetic differences. Clustering of the species based on cytological and RAPD data partly produced similar results, separating H. vulgare and H. spontaneum from each other. The species of H. marinum, H. glaucum and H. leporinum from the sect. Hordeastrum were grouped together, while H. violaceum H. bogdanii and H. brevisubulatum, from the sect. Stenostachys were placed in different clusters separated from each other. H. bulbosum and H. vulgare showed a close relationship, while H. spontaneum, H. distichon and H. vulgare were placed close to each other supporting their taxonomic position in Flora Iranica.
The karyotypes in 3 morphological forms of Typhonium trilobatum (L.) Schott such as the Green form, the Dark purple form and the Light purple form were compared after staining with orcein and CMA. The Green form and the Light purple form were found to possess 2n =18 chromosomes. However, 2n =17 chromosomes were observed in the Dark purple form. One chromosome in pair IX was absent in this form. The karyotypic features revealed that the Dark purple form might be originated from the Green form as monosomic. The centromeric formula was determined 16m+2ac in the Green form, 11m+4sm+2ac in the Dark purple form and 13m+5sm in the Light purple form. The Dark purple form showed more heterogeneous karyotype and may be considered as more advanced than the other 2 forms. No CMA band was found in the Green form. The Dark purple and the Light purple forms were found to possess distinct CMA banding pattern. With the help of CMA banding, it was possible to identify some chromosomes in these 2 forms. Few chromosome pairs in both the forms showed heteromorphicity in respect of CMA banding pattern indicating the occurrence of structural aberration. Morphology, distinct karyotypic features and CMA banding pattern suggested for placing the Green form in different taxonomic rank, while the Dark purple form might be considered as a monosomic variety of Typhonium trilobatum.
The chromosomes of the chevron snakehead fish (Channa striata) from Khon Kaen and Mahasarakam provinces, Northeast Thailand, were investigated by using conventional staining and Ag-NOR staining techniques. The diploid chromosome number of all 2 populations was 2n=42, with karyotype composed of 6 metacentric, 2 acrocentric and 34 telocentric chromosomes, NF=50, without heteromorphic sex chromosomes. This is a new report of karyotype in the C. striata. Ag-NOR was located on region adjacent to the centromere of chromosome pair 14. Here we first demonstrated Ag-NOR bands in snakehead fish from Thailand. In the future, basic knowledge about C. striata and its cytogenetics will be applied to studies of breeding, conservation and chromosome evolution in this fish.
Karyotype macrostructure and nucleolar organizer regions have often been studied in Neotropical siluriform fishes, but data about structural rearrangements and gene mapping are scarce. 5S rDNA is localized and characterized in Sorubiminae species (Steindachneridion melanodermatum and S. scriptum) using fluorescence in situ hybridization, C- and G-banding and restriction enzyme banding (AluI, BamHI and EcoRI). Chromosome mapping of 5S rDNA genes showed only one site located on the short arms of subtelocentric chromosome pair (chromosome 23) in both species, with no apparent polymorphisms. This region is C-positive and shows a clear G-band, having no cleavage sites for the restriction enzymes tested. These genes are not syntenical with the 18S ones and their karyotype location remains conserved in the species studied, appearing as a cytogenetic marker.
The molecular organization of mitochondrial-nucleoids (mt-nucleoids) isolated from BY-2 cultured tobacco (Nicotiana tabacum L.) cells was analyzed. Fluorescence microscopy using 4′,6-diamidino-2-phenylindole (DAPI) revealed that isolated mt-nucleoids retained the compact structural organization as that observed in vivo. Treatments of mt-nucleoids with DNase I, proteinase K and 2 M NaCl resulted in the disappearance, partial swelling, or complete dispersion of their DAPI-fluorescence, respectively, whereas treatment with RNase A did not affect their compact appearance. These results suggest that the compact structure of mt-nucleoids is maintained by electrostatic interaction between DNA and proteins. When mt-nucleoids that were treated with micrococcal nuclease (MNase) were analyzed by agarose gel electrophoresis, a ladder-like electrophoretic pattern of DNA, whose minimum fragment size was about 75 bp, was observed. This result suggests the presence of nucleosome-like, repetitive structures in the mt-nucleoids. Treatment of mt-nucleoids with increasing concentrations of NaCl gradually solubilized various proteins, including those with DNA-binding activities, which was accompanied by gradual dispersion of the mt-nucleoid structure. This result suggests that a variety of DNA-binding proteins with differing degrees of binding strength are present in the mt-nucleoids, and are involved in the compact organization of DNA-protein complexes at various levels. Detailed analyses of mt-nucleoids by Southwestern blotting, SDS-DNA PAGE, and DNA-cellulose affinity chromatography revealed the presence of many different DNA-binding proteins in the 2 M NaCl-soluble fraction of mt-nucleoids, which are expected to be involved in the compact organization of mt-nucleoids at various levels.
Some cysteine proteases are expressed in nodules of leguminous plants. AsNodf32, one of the nodulins of Astragalus sinicus, is a cysteine protease of the papain super family and is expressed strongly in mature nodules. To date, functions of proteinases in the nodules have not been clarified. Homologues of AsNodf32 were identified in the EST library of the model legume Lotus japonicus. The expression of homologous proteinase genes was strongly enhanced in mature nodules. Subcellular localization of one of the L. japonicus proteinases, LjCyp2, was studied using tobacco BY-2 cells. The localization of the LjCyp2-GFP-fusion protein changed depending on the cell growth phase. GFP fluorescence was observed in the cytoplasm of rapidly growing cells while the fluorescence was observed solely in the vacuoles of cells at the stationary phase. Cyclical changes of the localization observed in BY-2 cells may reflect control mechanism of LjCyp2 functions in the nodule.
The strawberry, genus Fragaria (Rosaceae), has a basic chromosome of x=7, and is comprised of 20 wild species having an euploid series from diploid (2n=2x=14) through decaploid (2n=10x=70). Few karyotypes of species in this genus have been reported. The objective of this research was to determine the chromosomal morphology and karyotype analysis of wild diploid, tetraploid and hexaploid Fragaria species. Somatic chromosome images of 20 genotypes of diploids, tetraploids, and hexaploids were taken at the metaphase stage of mitosis under a light microscope. Karyotype analysis was performed in 17 accessions. The phylogenetic relationships between species were constructed using cluster analysis based on karyotypic similarity. Somatic chromosome numbers of wild diploid, tetraploid and hexaploid species were 2n=2x=14, 2n=4x=28 and 2n=6x=42. Chromosome morphology in wild diploid species had greater uniformity than that in the tetraploid species. Results of the cluster analysis showed that the diploid and tetraploid species reside in separate clades, with one exception. Fragaria tibetica, a tetraploid, clustered with the diploid species clade. The hexaploid, F. moschata, clustered with the tetraploid species clade.