In vitro techniques offer opportunity to broaden genetic variability by overcoming reproductive barriers between crop species. As an initial step for the exploitation of such techniques, we have established regeneration protocols for cultivated and wild sorghum species. The latter are important sources of insect resistance. The present study deals with immature inflorescence culture and cytogenetic stability of a wild Parasorghum species viz., S. australiense (2n=20). Regeneration was observed at high frequency (≥80%) on MS medium supplemented with kinetin (1.0 mg/l) and BAP (1.0 mg/l). Meiotic analysis of regenerants revealed somaclonal variation among regenerants from 12 month-old cultures. Chromosomal variations like aneuploids, hypodiploids, quadrivalent associations and tetraploids were found in the regenerated plants. RAPD analysis with PCR revealed polymorphism in these cytological variants. The protocol developed here might be used as a basis for achieving high frequency of regeneration and generating cytogenetic variants. Some of the variants might be useful in conventional breeding programs and for gene transfer studies from wild to cultivated species by somatic hybridization.
Twenty-nine species and 15 fungal genera were collected from 30 samples of Egyptian date fruits incubated on 50% sucrose-Czapek's agar medium at 27°C. Eurotium was the most frequent genus and occurred in 83.3% of the samples contributing 22.6% of total fungi. For further genotypic characterization, the genus Eurotium represented by 5 species was compared with some type strains from culture collection of Institute of Applied Microbiology, Agricultural Sciences University, Austria. Random amplified polymorphic DNA (RAPD) markers were used for the estimation of genetic variability in this genus. Using 3 primers for the analysis, distinct fragments were obtained. The derived dendrogram clustered the strains according to the species.
The location and morphological features of the blood cells found in the pupal ovary of workers and queens of Apis mellifera are described in relationship with their probable function in the ovary differentiation. The hemocytes from inside the ovarioles are different in both castes. In queens their morphology suggest an action in the tunica propria production, while in workers it suggest a phagocytic activity. The hemocytes present in the intersticial tissue are phagocytes in both castes, and may be responsible by the ovary shapping during metamorphosis.
Morphological and cytological characterization of a nuclear male sterile line (MS-12) of chilli revealed association of 3 morphological markers, viz., taller plant height, erect plant growth habit and dark purple anthers with the male sterile plants. A scheme has been proposed to identify and remove majority of male fertile plants from hybrid seed production field at early growth stage based on shorter plant height and intermediate growth habit (male fertile) followed by identification and removal of the remaining male fertile plants on the basis of light purple anthers at later stage. Meiotic analyses of male fertile and male sterile plants revealed that MS-12 was a sporogenous male sterile line, in which microspores degenerated immediately after formation of the tetrads.
The present investigation study the morphological and cytogenetic effects of Calotropis procera extract on Vicia faba L. The control plants being normal while treated ones are significantly affected. Four concentrations (5, 15, 30, 60%) of this extract were applied for 3 duration time. For treated seeds, low doses caused increase in mitotic indix (MI) and exhibit stimulatory effect on percentage of germination and plant height. On the other hand high concentratiosn gave rise to substantial reduction in MI, percentage of germination and plant height and all were found dose and time dependent. In contrast, all parameters tested for treated roots were found negatively affected with no exception and found more harmful and effective compared to seed treatment experiment. Various types of mitotic and meiotic abnormalities were observed. Their percentage of these abnormalities was also found dose and time dependent. Stickiness type was found more frequent compared with other types. The extract also affect chromosome association during meiosis. Chromosome pairing, chiasma frequency and pollen fertility were found negatively affected and dose dependent. The present data confirm the use of this extract as insect control at high concentrations is harmful to plants as non-target organism. It also recommend the use of lower concentration (15%), which has a significant affect on insect with very low side effects on plants.
Three perciform species associated to coral reefs were, for the first time, investigated under a cytogenetic focus : Holacanthus ciliaris and H. tricolor from family Pomacanthidae and Chaetodon striatus from family Chaetodontidae. Individuals were collected at different sites along Atlantic coast of Brazil. All of them showed similar chromosomal features, considered primitive for the order. These characteristics are 2n=48, NF=48, NORs located at interstitial position on long arms of a single chromosomal pair and discrete heterochromatic blocks at centromeres and NORs.
The morphology of the pachytene chromosomes of Hyoscyamus muticus (2n=28) was analysed. All 14 pachytene chromosomes were clearly identified on the basis of length, arm ratio, distribution of heterochromatin and presence of characteristic chromomeres. The pachytene chromosomes were differentiated into proximal heterochromatic regions surrounding the centromere and distal euchromatic regions. Chromosomes were numbered from 1 to 14 following a descending order of length. The physical lengths of the 14 chromosome pairs ranged from 28.23 to 101.47 μm with a total length of 877.69 μm. Based on the centromere position, the complement consisted of 4 chromosomes with median centromeres, 7 with subterminal centromeres and 3 with terminal centromeres.
The aim of this study was to investigate potential clastogenicity/genotoxicity of the antibiotic spiramycin in bone marrow cells of rats (Rattus norvegicus var. albinos). In the study, spiramycin induced the chromosome aberations at all concentrations (100, 200, 400 mg/kg bwt. (body weight) /d oral) in 21 d when compared with the solvent control group (sunflower seed oil). In addition, spiramycin induced the chromosomal aberration (CA) at only 200 mg/kg bwt. intraperitoneal (i.p.) in 12 h and 100 and 400 mg/kg bwt. i.p. in 24 h when compared with the control group. Spiramycin induced the micronucleated polichromatic erythrocytes (MNPCE) only at 200 mg/kg bwt. i.p. in 12 h and 100 mg/kg bwt. i.p. in 24 h. However, there was no significant difference in the formation of micronuclei at the other concentrations.
Previous investigations in our lab have indicated that cells of patients with Werner's syndrome (WS), a premature aging disorder, contain unstable heterochromatin. That instability results in heterochromatin being sloughed off the surface of chromosomes during high temperature incubation in phosphate buffer. In addition, WS interphase chromocenters are sloughed off into patches and rings during such incubation. Recent investigations in our lab have promulgated the hypothesis that the phenomenon of sister chromatid exchange (SCE) may, likewise, be produced by sloughing off of unstable heterochromatin from the chromosome surface. This hypothesis predicts that cells exhibiting a high SCE frequency, such as Fanconi's anemia (FA), may likewise contain unstable heterochromatin. In order to test this hypothesis, FA cells were subjected to SCE staining conditions, confirming the presence of unstable heterochromatin.
Autotetraploid plants of Aloe vera L. were induced by colchicine treatment. Diploid shoot tips (2n=2x=14) were treated by immersion of the rhizomes in colchicine concentrations of 0.05%, 0.10% and 0.15% at exposure times of 6, 12, 18 and 24 h. The highest proportion of polyploid plants (5.9%) with 2n=4x=28 was obtained from a 0.15% colchicine and 24 h combination. Diploid/tetraploid chimerical plants were observed at the lowest colchicine concentration/time treatments. Expression of gigantism in morphological and cytological characters, such as, width and thickness of the leaves, size and frequency of juvenile foliar spots, plant weight, size of epidermal and root cells, were noted in autotetraploid plants with a significant decrease in stomatal frequency.
The transfer of stationary-phase cultured tobacco (Nicotiana tabacum L.) Bright Yellow-2 (BY-2) cells into new medium induces active proplastid division. To examine the relationship between ftsZ gene expression and proplastid division, the transcript and protein levels of the ftsZ gene in stationary-phase cells and in 12-h-old cells after medium renewal were compared. RNA-gel blot analysis revealed that transcript levels for both types of ftsZ genes, ftsZ1 and ftsZ2, increased markedly following medium renewal. Similarly, immunoblot analysis using antibodies to lily FtsZ protein showed a remarkable increase in FtsZ protein following medium renewal. Furthermore, immuno-fluorescence microscopic observation revealed that FtsZ proteins appeared as multiple rings transversely aligned in elongated proplastids, which will be fragmented by multiple divisions during culture. These results suggest that FtsZ proteins may have a role in multiple division of proplastids.
FtsZ protein is essential for bacterial cell division, and is also involved in plastid and mitochondrial division. However, little is known of the function of FtsZ in the mitochondrial division process. Here, using electron microscopy, we revealed that the mitochondrial FtsZ (CmFtsZ 1) localizes at the constricted isthmus of a dividing mitochondrion on the inner (matrix-side) surface of the mitochondrion. These results strongly suggest that the mitochondrial FtsZ acts as a ring structure on the inner surface of mitochondria.
Arabidopsis thaliana possesses 5 eubacteria-derived and nuclear-encoded genes, AtFtsZ1-1, AtFtsZ2-1, AtFtsZ2-2, AtMinD1, and AtMinE1, which are involved in chloroplast division. AtMinE1 is a homologue of the eubacterial septum site-determining factor minE. It has been demonstrated that the overexpression of AtMinE1 in Arabidopsis leads to the disruption of chloroplast division. To further confirm the role of AtMinE1 in chloroplast division, we newly constructed antisensetransgenic Arabidopsis plants with 3 to 4 fold reduced AtMinE1 expression. Chloroplasts of these lines were reduced in number, but individually enlarged, which indicates retarded chloroplast division. The results of this study demonstrate the requirement for a proper level of AtMinE1 expression, for normal control of chloroplast division.
Genus Fragaria consists of several species, ranging from diploid to octoploid, and including various types of sex determination. The genome size of Fragaria species is not known correctly, mainly because preparation of samples suitable for genome size estimation has been difficult. Moreover, it is difficult to choose a suitable standard material for estimation given the small genome size of Fragaria species. Our experimental data showed that the flower petal is a more suitable tissue for flow cytometry. We developed a new procedure, which prevents contamination of tissue samples with debris, and thus allows more accurate estimation of the DNA content during flow cytometry. Arabidopsis thaliana has been sequenced nearly complete, and the estimated genome size from the sequence data is 125 Mbp. We chose Arabidopsis thaliana as standard material. Using this approach, we successfully estimated the genome size of the diploid Fragaria species to be around 164 Mbp/C.
Three species of the genus Eucalyptus (E. dunni, E. grandis, E. saligna) and interspecific hybrid were studied cytogenetically. The Eucalyptus species and the hybrid showed a symmetrical karyotype with 2n=22 chromosomes, with chromosome length ranging from 0.67 to 1.39 μm. Karyotypic analysis indicated a homogenous morphology and chromosome number for the species and the hybrid studied here. Based on the karyotype asymmetry data, together with the chromosome morphology results, the hybrid presented close similarity to E. saligna, suggesting that the latter is one of the parental species involved in the production of the hybrid.