UV-A light (355 nm) irradiation (6μmol·m-2·sec-1) for I to 1000 sec of a microsomal fraction prepared from the mycelia of band and wild type strains of Neurospora crassa stimulated the binding of [α-32P] ATP and [α-32P] GTP to 4 NTP-binding proteins with the molecular weights, 58, 77, 83 and 129 kDa. In the former three molecules, 10-5-10-4 M NAD controlled the binding of [α-32P] ATP and [α-32P] GTP by UV-A light irradiation, and the further presence of pertussis toxin reduced the background binding of these nucleotides to these NTP-binding proteins.
Detailed somatic karyotype analysis was carried out in 6 species of Sesbania. Of these, four species namely aculeata, rostrata, aegyptica and speciosa were diploid with 2n=12 chromosomes, while the species grandiflora was a tetraploid with 2n=24 chromosomes. The other species, sesban has both diploid (2n=12) and tetraploid (2n=24) cytotypes. Considerable differences were observed among the different species in terms of total chromatin length and volume with the values ranging from as high as 47.07μm and 31.98μm3 in S. qrandiflora to as low as 18.31μm and 8.98μm3 in the species S. aegyptica. All diploid cytotypes except aculeata, exhibited one pair of SAT-chromosomes each, usually the second longest in the complement. In tetraploid forms two pairs of chromosomes (chro. 1, 2) carried secondary constriction in their long arms. The karyotypes of all species except aculeata were found to be symmetric with predominanty metacentric chromosomes. S. aculeata, however, had an asymmetric karyotype with 2 pairs of sub-metacentric and 1 pair of sub-telocentric chromosomes in addition to 3 metacentric pairs. Relative lengths, S% and TF% estimations also support the above view. The occurence of diploid and tetraploid forms in S. aculeata and S. sesban suggests the possibility of the existence of tetraploid forms in other Sesbania species also.
In a γ-ray induced male sterile mutant of pea, the ms gene inhibits meiotic initiation or arrests male meiosis either during pachytene, diplotene, prophase II or telophase II, or, permites its progression until microspore formation. The meiosis is abnormal involving PMCs, chromatin and/or nucleolar degeneration, nucleolar fragmentation or multiplication, sticky, clumped or clustered bivalency, chromatid breakages and irregular reunions, chromosomal stickness and unequal disjunction, abnormal monads to tetrad formations and complete microspore abortion. This mutant gene, msg3, causing these anomalies is non-allelic to the other seven ms genes isolated in pea. The ms gene action in this mutant is unique being non-stage and non-site-specific, diffuse and staggered. Existence of a constellation of meiotic anomalies accompanying meiotic progression indicates broad action spectrum of msg3 gene. The basis of evasion or endurance of about 50% PMCs and susceptibility of the remaining ones to the ms gene post-translational products is not known. The influence of gene mediated enzyme(s) deficiency in limiting meiotic progression cannot be ruled out. Likewise, the impact of the environment over the versatility and prodigiousness of ms gene action cannot be discounted. Can environmental influence be so selective or do buffering or inhibitory anther-specific genes exhibit variable or temporal and spatial gene action in the msg3 mutant of pea is also not known. Mutations in the highly conserved region in the PB promoter gene the ‘anther box’ may have led to the arrayed male meiotic anomalies in this mutant.
The genomic relations between the peach (P. persica, 2n=2x=16) and the plums (P. cerasifera, 2n=2x=16, and P. spinosa, 2n=4x=32) are not very well established. Such a knowledge will be necessary if interspecific hybridization has to be used for genetic improvement of fruit varieties. The present cytological study based on meiotic behaviour analyses of new diploid, triploid and tetraploid hybrids between plum and peach provided new information on the peachplum genome relationship. The diploid hybrids (P. cerasifera×P. persica) show a relatively regular pairing between the two genomes whereas the tetraploid form is characterized by the presence of an average of 13.75 bivalents per cell and a low frequency of multivalents (0.60 III and 0.42 IV). These results indicate a partial homology between the two species. Concerning the [P. spinosa×P. persica] hybrids, the meiotic behaviour shows that two out of the three constitutive genomes are almost homologous. Considering the meiotic behaviour already observed in related species P. spinosa and in [P. spinosa×P. cerasifera] triploid hybrids, together with the meiotic behaviour of [P. spinosa×P. persica] hybrids, it is likely that the bivalent pairing result from association between the two spinosa genomes. A comparative analysis of these different results leads to the conclusion that the peach genome is more remote from the P. spinosa genomes than the P. cerasifera is.
The silver-stained chromosomes are observed under a fluorescence microscope with trans-mitted-light excitation after fluorochroming with acridine orange. The difference between the scaffold and epichromatin becomes accentuated due to fluorescence of denatured DNA. It is concluded that the scaffold is surrounded by epichromatin which contains DNA.
The present study was carried out to localize DNA in the nucleolus-associated bodies (NABS) using specific staining and immunocytochemical labeling techniques in Pisum sativum L. These bodies are of interest as the functional components of plant nucleus. DNA-specific staining and labeling with anti-DNA, a monoclonal antibody, were employed to verify the presence of DNA in these bodies. The NABs do not contain any DNA as they show negative response to DNA specific stains and also when incubated with anti-DNA, they are almost devoid of any gold particles.
Mitotic chromosomes in six botanical varieties and six cultivars of barley, Hordeum vulgare L. were studied by Giemsa N-banding technique. Chromosomes 1 and 4 are metacentric and thus their short (S) and long (L) arms can not be differentiated through conventional staining method. These were easily differentiated on the basis of the bands on them. The classification of the bands was in accordance to Generalized Cytological Nomenclature of Cereal Chromosomes (GCNCC). Minor differences in the banding pattern among the studied varieties/cultivars were observed. The results indicated that all varieties of Hordeum investigated had characteristic banding pattern and polymorphism was evident on 1, 2, 4 and 6 chromosomes. Among the cultivars N-banding polymorphism was observed in interstitial regions of chromosomes 1, 2, 3 and 6. On the basis of these results it can be concluded that both varieties and cultivars may be identified due to their N-banding patterns.
The fate of chloroplast nuclei (cp-nuclei; cp-nucleoids) was followed during spermatogenesis and fertilization in the oogamous alga Volvox carteri by epifluorescence microsopy, after staining with 4'-6-diamidino-2-phenylindole (DAPI), and by quantification of chloroplast DNA by fluorimetry using a video-intensified, photon counting (VIM) system. The mature androgonidium contains a single large chloroplast, which has many pyrenoids surrounded by large cp-nuclei. Six cell divisions occur after androgonidia maturation to form 64 sperm cells in a packet. During the formation of sperm packets, the cell-nuclei are synthesized in relation to the mitotic cycle. By contrast, the volume of each spermatocyte and the amount of cp-DNA in each choloroplast are reduced stepwise by each division. Finally at the sperm cell stage, the volume of them reachs approximately 1/64 of the original values in the mature androgonidium. In sperm packets, each sperm cell has 3-6 cp-nuclei in their chloroplast. In contrast, mature egg cells in the female colonies have many dispersed cpnuclei in a large chloroplast. When the sperm packets are broken to release sperms at the surface of the fmale colonies, almost all of the sperms show up to three cp-nuclei in the chloroplast. After the sperms have penetrated into the female colonies, approximately 20% of the sperms show no cp-nuclei in the chloroplast, and 50% of them show only one cp-nucleus and other have up to three cp-unclei. And the amount of cp-DNA per sperm cell determined by VIM system shows the remarkable decrease. After plasmogamy, cp-nuclei originating from the sperms could not be recognized at all in the egg cytoplasm. These observations suggest that maternal inheritance of chloroplast genes in Volvox is certainly present which would be based on the preferential degeneration of the male chloroplast nuclei as in other green plants.
Polytene chromosomes of Stylonychia mytilus are formed during the development of a macronucleus from a micronucleus after sexual processes such as the conjugation. These chromosomes have many similarities to the polytene chromosomes of the Diptera. This paper deals with the morphological study of a chromosomal loop observed in three different phases of development of polytene chromosomes in Stylonychia mytilus. It was formed in the early stages possibly due to the existence of an inversion in one of the two homologous chromosomes and the subsequent pairing of the homologous tracts. This could answer the question regarding the existence or not of somatic pairing during the development of polytene chromosomes of this species.
Standard maps of polytene salivary gland chromosomes of black fly species Simulium (Simulium) singtamense have been prepared. It revealed normal simuliid complement of n=3 chromosomes. Two homologues of each polytene chromosomes are tightly synapsed and are provided with identifiable centromeres. First two chromosomes are metacentric while the third one is submetacentric. Characteristic landmarks of polytene chromosomes such as Balbiani Ring, nucleolar organiser, puff and characteristic banding patterns have been described and compared with those of congeneric species.
The karyotypes of twelve diploid taxa (2n=20) of the Stylosanthes, Leguminosae, were analysed. The genus has a very conservative karyological pattern. The comparison among taxa belonging to the controversial S. guiananesis species complex, showed clear differences in size of their chromosome complements and morphology, which suggest that this group is under a process of chromosome evolution by the occurrence of rearrangements and changes in DNA content. The analysis of four species unrelated to this complex showed clear differences among their karyotypes.
Karyotypic studies were done on five Japanese species of Geum. These Geum species had gradual and symmetric karyotypes in common. Karyotypic formulae of the five species were the following: G. aleppicum (6x), 2n=42=24m+10sm+4tsm+4st; G. calthaefolium var. nipponicum (6x), 2n=42=32m+6sm+2st+2tst; G. japonicum (6x), 2n=42=26m+8sm+4tsm+4st; G. macrophyllum var. sachalinense (6x), 2n=42=26m+8sm+4tsm+4st; G. pentapetalum (2x), 2n=14=8m+4sm+2tt. The study of karyotypes of the Japanese Geum species reveals that G. aleppicum, G. japonicum and G. macrophyllum var. sachalinense have close relationship, whereas G. calithaefolium var. nipponicum is distinct from the other hexaploid Geum. Also, G. pentapetalum was quite distinct from the other Japanese Geum species studied.
The preferential destruction of the chloroplast DNA (cp-DNA) from the male-derived chloroplast 40 min after mating of male and female gametes in Chlamydomonas reinhardtii can explain the inheritance of maternal cp-DNA (Kuroiwa et al. 1982, Kuroiwa 1991). However, there is no information available regarding the structural changes which would be expected to precede the preferential digestion of cp-DNA. Chlorophyll pigments, chloroplast nuclei (cp-nuclei; nucleoids) and fine structures of chloroplasts were examined in young zygotes after mating of male and female gametes in the isogamous alga Monostroma latissimum by epifluorescence microscopy, after staining with 4'-6-diamidino-2-phenylindole DAPI), and by electron microscopy. Each gamete has a large cup-shaped chloroplast which contains several cp-nuclei. At 60 min after mating of male and female gametes, the preferential disappearance of the cp-nuclei in male-derived chloroplasts can be observed in more than 50% of the young zygotes. Epifluorescence microscopy revealed that preferential release of chlorophyll pigments from the male-derived chloroplast precede the disappearance of cp-nuclei. This release of chlorophylls may be due to a change in the membrane systems. Electron microscopy shows that preferntial swelling of membrane systems occurs in just one of the chloroplasts in the young zygotes. Based on these results, we suggest that the release of chlorophyll may be due to changes in the membrane systems, which promote the preferential disappearance of the male-derived cp-nuclei.
We examined the organization of organelle DNA in the two algae, Cyanidium caldarium RK-1 and C. caldrium M-8 with epifluorescence microscopy and molecular-biological techniques. The plastid nucleus (pt-nucleus, a complex of DNA and proteins) is located in the central area of the plastid in C. caldarium RK-1, while the ring-shaped pt-nucleus is located at the periphery of the petal-like plastid in C. caldarium M-8. The results suggest that C. caladarium RK-1 markedly differs from C. caldarium M-8 in an evolutionary tree. To confirm the result, we examined the fragment that contained rbcL. The trpA (the gene for the α subunit of the tryptophan synthase), which was located on the vicinity of the rbcL, was found on the plastid genome of the “primitive” unicellular red alga, C. caldarium RK-1, while the gene could not be found on the plastid genome of the C. calardium M-8 (Galdieria sulphuraria). This is the first example of typtophan synthase encoded on the plastid genome. The results suggest that the trpA gene may have relocated from the plastid genome to the cellnuclear genome for longer ago than the genes that have been considered to date to have been lost from plastid genomes in the advanced members of plants.