Chromosomal relationship between humans and dusky langurs (Trachypithecus obscurus, 2n=44) was established by chromosome painting using chromosome specific DNA probes of the human chromosome 1 and 19 which each gave hybridization signals on two non-homologous dusky langur chromosomes. The results show that the human chromosome 1 and 19 probes hybridized to three regions of dusky langur on the autosomes 6 and 8. The human chromosome 1 probe hybridized to one region on the dusky langur chromosome 6 and two regions on the dusky langur chromosome 8, where the human chromosome 19 probe hybridized with the same pattern but on different regions. Hybridization patterns of human painting probes on dusky langur, when compared with the data of other species in the same genus suggest that the alternating hybridization pattern of the conserved segments homologous to human chromosomes 1 and 19 on dusky langur chromosomes 6 and 8 is the result of the translocation followed by the pericentric inversion. Moreover, the present research also indicates that the dusky langur's chromosomes 6 and 8 have the same hybridization patterns as other Asian colobines.
The present article describes an efficient technique for micropropagation and microtuberization of two species of Gloriosa, G. orangea and G. rothschildiana of Colchicaceae, the colchicine yielding plants. The plants were propagated in culture through apical shoot bud multiplication using modified Murashige and Skoog's nutrient medium (MS) supplemented with 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA) in presence of two different concentrations of sucrose (3 and 6%). The process of microtuberization was found to be quite efficient in MS containing 3% sucrose, producing about 180–240 tubers per culture vessel within 6 months or less. On the other hand, the medium with 6% sucrose level induced microtuberization 2 weeks earlier with reduced rate of regeneration. The microtubers from 3% media showed 97% germination rate. The best result was obtained in a medium containing BAP (17.76 μM) and NAA (2.15 μM) with about 18–24 shoots and 14–21 microtubers/shoot. A 1.7 fold increase in colchicine accumulation in G. rothschildiana and a 2.0 fold increase in G. orangea estimated through High Pressure Liquid Chromatography (HPLC) were observed as compared to in vivo tubers. The extracted colchicine showed better efficacy than standard colchicine from Sigma Chemical Co. in treated root tip cells of Allium sativum L. and Mucuna pruriens L. In both these test plant systems, the extracted colchicine induced both polyploidy and diplochromatid formation at variable rates and the values were little higher in G. orangea than in G. rothschildiana. Moreover, G. orangea responded better than G. rothschildiana against the same concentrations of plant growth regulators and showed better colchicine accumulation as well.
Karyomorphological investigation have been carried out in ten different accessions of Carthamus tinctorius belonging to the tribe Cynareae (thistle), sub-family Tubifloreae of family Compositae. For concrete studies we explored the details of 3D karyotype using length and volume of the chromosomes and the chromosome complements, in addition to several other related parameters. The observations show variability pertaining to length and volume as well as morphology of chromosomes indicating the structural chromosome polymorphism. All the accessions possessed 2n=24 and symmetrical or slightly asymmetrical karyotype. The accessions belonging to the same species were showing intra-specific and inter-specific chromosome polymorphism.
Embryo abortion of Fagopyrum esculentum under high temperature stress was studied, firstly, at 1–3 d after pollination (DAP) with light and transmission electron microscope (TEM). The first sign of degeneration appeared at the subcellar level in the embryo sac within 2 DAP. Embryo development is significantly slowed. Almost all abortion is at the proembryonic, 8 to 24 cell stage. Embryo abortion is characterized by the appearance of large vacuoles in the embryo proper. The cytoplasm either is low in density or shows gradual condensation. And various changes occur in the abnormal cytoplasm: the cell walls expand, the ER becomes vesiculate, and osmiophilic deposits accumulate along the cell wall. The central cell degenerates to a greater degree. In particular, endosperm is absent or degenerates with either electron-dense condensed cytoplasm or dispersed cytoplasm in the early free-nuclear stage. The membrane system of organelles collapses. Dictyosomes and ER also become highly vesiculated and almost all organelles disperse within the central cell, while ribosome number is sharply decreased. In the aborted embryo sac, nucellar cells show a high degree of degeneration with condensed cytoplasm and vacuolation. As both of the nucellus and endosperm are heavily damaged by heat-stress of high temperature, this damage leads to the loss of normal endosperm function. Nutrients are not stored or transported to the developing embryo and, thus, embryo abortion is triggered before the embryo becomes autophytic.
Meiotic studies carried out in the diploid (2n=2x=16) Clematis flammula L. revealed the occurrence of cytomixis. Chromatin transfer is observed from early prophase up to tetrad stage. Although the percentage of PMCs involved in chromatin transfer is low, but it definitely impairs the meiotic process. Cytomixis induces various other associated meiotic abnormalities which are observed at different meiotic stages. These meiotic abnormalities include; chromatin stickiness, laggards and chromatin bridges at anaphases and telophases, spindle abnormality, micronuclei at telophases and tetrad stages, micromicrospores and included micronuclei in microspores. Consequent to chromatin transfer, some pollen malformation and pollen grains of heterogenous sizes are resulted which are classified into small, medium and large sized. Another interesting phenomenon which has been observed during the present study is the occurrence of included micronuclei in the microspores and micrmicrospores in tetrads. Cytomixis and other meiotic abnormalities are reported for the first time in the species. We here also report for the first time the occurrence of B-chromosome in the species.
The green macroalgal genus Ulva (incl. Enteromorpha) is the most common, ubiquitous, and environmentally important genus. Certain taxa serve as experimental organisms for fundamental research such as algal genetics. We established three lines of Ulva compressa from the coasts of Japan, named Ehime, Nagasaki and Iwate lines which consist of two strains of different mating types. For further genetic research of U. compressa, genetic markers are imperative. Here we report nine polymorphic microsatellite markers developed from enriched genomic libraries. The number of alleles per locus ranged from 7 to 19. These markers will be applicable for investigations of population structure.
We investigated the effect of antibiotics that specifically inhibit peptidoglycan synthesis on plastid division in pteridophytes by comparing the numbers of plastids in normal and antibiotic-treated pteridophyte cells. Plastid numbers were unaffected in Moniliformopses cells but decreased in Lycophytina cells after treatment with the β-lactam antibiotic ampicillin. However, cells of all four pteridophyte species exhibited decreased plastid numbers when treated with the antibiotic fosfomycin. Together, these results suggest that the Mur genes may be related to plastid division in pteridophytes, as demonstrated for certain bryophytes.
Iris setosa var. hondoensis and I. setosa var. nasuensis are endemic to Japan, and their origins still remain to be clarified. In this study, we report the characterization of interspecific hybrids (allotriploids) from the cross between autotetraploid I. setosa var. setosa (4x) and diploid I. laevigata (2n=32) and their relationship to I. setosa var. hondoensis or I. setosa var. nasuensis. In reciprocal crosses between I. setosa var. setosa (2x, 4x) and I. laevigata, progeny plants were obtained only in the cross between I. setosa var. setosa (4x) and I. laevigata (2x). These progenies were identified as allotriploids (2n=54) and their aneuploids (2n=53) of I. setosa var. setosa (4x)×I. laevigata (2x) by flow cytometric (FCM), cytological and random amplified polymorphic DNA (RAPD) analyses, and the five hybrids (SL1–5) except SL6 were characterized. Furthermore, these characteristics of I. setosa var. hondoensis and I. setosa var. nasuensis were compared with those of SL1–5. These varieties were also examined by FCM, cytological, RAPD and cleaved amplified polymorphic sequence (CAPS) analyses, which comparative analyses showed that varieties have the hybrid nature between I. setosa var. setosa and I. laevigata, and maternal plants are organelle DNAs of the former species.
Calligonum polygonoides is an endemic and threatened species reported from semi-arid and arid zones of Rajasthan and adjoining desert belt especially on loose sand dunes. Polygonaceae, the family to which C. polygonoides belongs has about 12 genera distributed in India which comprises about 115 species, distributed chiefly in north temperate, arctic and southern regions, whereas a few are spread over tropical regions. This is the first attempt to determine the gametic chromosome number of C. polygonoides from various populations of arid zone regions in western Rajasthan. The genetic variation analyzed is based on chromosome associations, chiasma frequency at diplotene/diakinesis/metaphase I and pattern of disjunction of chromosomes at anaphase I.
Diploid individuals (2n=18) of Chrysanthemum zawadskii, C. indicum and C. boreale, two or all three of which often occur together in the wild in East Asia, have diverse metaphase karyotypes. We hypothesised that the diverse karyotypes result from chromosome rearrangements. To test this, we investigated chromosomal behaviour during pollen mother cell (PMC) meiosis and pollen fertility, using 33 individuals collected from seven populations in Korea. All individuals contained one or two multivalents (mostly quadrivalents) at late prophase I and metaphase I in some PMCs (approximately 17–37%), and at least one or two bivalents composed of homologous chromosomes of different length and centromere position in all PMCs. This meiotic chromosomal behaviour indicates that chromosome rearrangements, i.e., reciprocal translocation and unequal crossing-over, are prevalent in Chrysanthemum species. Nevertheless, because of successful chromosome segregation in anaphase I and II, they produce ample stainable pollen with different chromosome complements. Fertilization by such gametes should result in diverse somatic karyotypes. We also discuss the possibility that older or relatively recent hybridization events have led to a high rate of irregular meiotic chromosome behaviours and pollen sterility, particularly in C. indicum.
The unicellular red alga Cyanidioschyzon merolae is tolerant of high levels of several different metal ions. Cells of the alga cultured with divalent or trivalent metal ions at 10 mM contained elevated concentrations of each metal. The highest tolerance was shown for Al followed by Fe, Cu>Ni>Zn>Mn. The viability and morphology of the cells were investigated for different periods of time after metal addition. In contrast to land plants, C. merolae exhibited a very high tolerance to metal ions, but the response varied according to the metal ion added. In particular, Mn, Zn and Ni ions affected the structure and function of the chloroplast, and markedly reduced the cell viability. Nevertheless, the tolerance of C. merolae to metal ions is the highest among reported eukaryotic cells. Cellular mechanisms for detoxification or defense against metal ions must be well developed in this alga.
Excised apical frond primordia from three different Azolla species namely A. filiculoides, A. microphylla and A. pinnata in liquid culture gave whole rooted juvenile fern within 2 week culture in agar-solidified MS (Murashige and Skoog (1962)) medium augmented with 0.03 mg/l kinetin in combination with 0.01 mg l−1 indole-3-acetic acid (IAA) and additionally 0.001 mg l−1 folic acid. Axenic ferns were multiplied through successive subculture of frond primordia. On transfer to a liquid N-minus (nitrogen minus) medium they grew with much reduced fronds and elongated roots showing a negligible biomass gain over a 12 week culture. Prolific growth was resumed following transfer to a modified liquid N-plus (nitrogen plus) medium contained in a fabricated aquarium-styled propagator. On comparison vis-à-vis the parental isolates with respect to biomass, chlorophyll content, total nitrogen content as well as the nitrogenase activity, such newly established cultures were identified to be devoid of the cyanobacterial symbiont. The Anabaena-free nature of these plants was further confirmed by enzymatic digestion of fronds. The implication of this investigation is discussed aiming at genetic improvement of this agronomically useful biofertilizer for rice cultivation.
Karyotypic analyses were performed in twenty populations of fourteen Bromus species and varieties from three sections of Bromus L., Genea Dum., and Pnigma Dumort., growing in Iran for the first time. The chromosome numbers of B. stenostachyus, B. tomentosus and B. kopetdaghensis are new and new polyploidy level has been reported for B. cappadocicus, B. erectus, B. variegatus and B. tomentosus. The ANOVA and LSD tests revealed a significant differences (p<0.01) in the size of chromosomes as well as chromosome arms among the populations of each species, among species with similar somatic chromosome numbers in each section and also among the three sections studied, indicting the role of the chromatin change in the species diversification in the genus Bromus. PCA analysis showed that the mean chromatin length of the chromosomes is one of the most variable karyotypic features among the Bromus species studied. Pearson correlation determined among the karyotypic features showed that the increase in the mean chromatin length has been accompanied with an increase in the size of both short and long arms of the chromosomes. The increase in the mean chromatin length showed a significant correlation with the TF percentage therefore increasing the level of karyotype symmetry.
Meiotic investigations were carried out on 29 species of 13 Polypetalae families from the cold deserts of Lahaul-Spiti and adjoining areas of north-west Himalaya. Additional/varied cytotypes have been reported for two species for the first time. The present chromosome count of 2n=18 in Hypericum elodeoides adds a new cytotype to the existing diploid (2n=2x=16) chromosome number. The meiotic count of 2n=2x=14 in Potentilla fruticosa var. rigida adds a new diploid cytotype to the already existing tetraploid (2n=4x=28) cytotype. The chromosome numbers of 10 species viz. Aquilegia fragrans (n=7), Silene vulgaris (n=12), Astragalus bicuspis (n=8), Cicer microphyllum (n=8), Potentilla fruticosa var. rigida (n=7), Melilotus officinalis (n=8), Rosa webbiana (n=7), Bergenia stracheyi (n=17), Sedum ewersii (n=11) and Datisca cannabina (n=11) are new records for India. The cytomixis involving the inter pollen mother cell transfer of chromatin is observed in Caltha palustris, Astragalus bicuspis, Meconopsis aculeata, Melilotus officinalis, Potentilla fruticosa var. rigida and Trifolium pratens. In Caltha palustris the cytomixis (20–28%) results into various meiotic abnormalities and heterogeneous sized pollen grains. In other species the frequency of PMCs (pollen mother cells) involved in chromatin transfer is very low (0.1–1%) without affecting the pollen fertility.