Showing papers by "Archana Sharma published in 1984"
01 Jul 1984
TL;DR: The variation in 4C DNA amounts between the species of Calathea was not distinct but in two species of Maranta, a notable variation in nuclear DNA amount was recorded and the amount of nuclear DNA did not show direct correlation with the total chromosome length and volume.
Abstract: Karyological analysis including determination of somatic chromosome number, total chromosome length, volume and karyotype formula andin situ estimation of 4C-nuclear DNA amount were carried out on 14 different species and varieties of the generaCalathea, Maranta andStromanthe. The 4C nuclear DNA amount was estimated through Feulgen microspectrophotometry following single wavelength method and expressed in arbitrary units of relative absorbances. The variation in 4C DNA amounts between the species ofCalathea was not distinct but in two species ofMaranta, a notable variation in nuclear DNA amount was recorded. In addition, the amount of nuclear DNA did not show direct correlation with the total chromosome length and volume. The absence of wide difference in nuclear DNA content at an interspecific level might have some adaptive value.
19 citations
TL;DR: When given to mice either in a single ip injection or in 30 daily oral doses of 2 mg/kg, tert-butylhydroquinone had severe clastogenic effects on the bone-marrow cells, however mitostatic activity was observed only with the acute treatment.
12 citations
TL;DR: A total of 18 metallic salts belonging to seven groups of the periodic table applied in sublethal chronic doses on plant and animal cells in vivo for their comparative action on cell division showed a general decrease with increased dosage and period of treatment.
Abstract: A total of 18 metallic salts belonging to seven groups of the periodic table have been applied in sublethal chronic doses on plant and animal cells in vivo for their comparative action on cell division.Usually within the members of a particular group inhibition of mitosis and induction of chromosomal abnormalities increased with increasing molecular weight. There was a general direct proportionality with dosage applied and the cytotoxic action, though occasionally there was an increase in very low doses. These effects were more general in nature and could not be specifically attributed to any particular cell component. The amounts of total DNA and RNA showed a general decrease with increased dosage and period of treatment.
10 citations
TL;DR: Using Giemsa C-banding technique, the existence of interchromosomal connections in well spread root tip metaphase plates in a variety of plant species has been demonstrated and the possible role in establishing the homologous and non-homologous association in the somatic chromosomes and maintaining the spatial relationship of the genetic apparatus is indicated.
Abstract: Using Giemsa C-banding technique, the existence of interchromosomal connections in well spread root tip metaphase plates in a variety of plant species has been demonstrated. Various types of interchromosomal connections are observed, involving satellite, telomeres, interstitial regions and in a few cases centromeres, too. The possible role of these interchromosomal connections in establishing the homologous and non-homologous association in the somatic chromosomes and maintaining the spatial relationship of the genetic apparatus is indicated. In the majority of the cases the connections are made up of constitutive heterochromatin.
6 citations
TL;DR: Ten species belonging to three genera of the family Magnoliaceae, with the application of improved techniques, show uniformity of chromosome number, graded karyotypes, with mostly metacentric chromosomes and the size ranging from medium to small.
Abstract: Chromosome study has been carried out on ten species belonging to three genera of the family Magnoliaceae, with the application of improved techniques. Only two species, namely Magnolia liliflora (2n=76) and M. grandiflora (2n=114) show high chromosome numbers, the rest showing 2n=38 chromosomes. The general features include uniformity of chromosome number, graded karyotypes, with mostly metacentric chromosomes and the size ranging from medium to small. The plants, with high chromosome number in the polyploid species, have long chromosomes and show no reduction in chromosome size. The species differ from one another in the type and number of chromosomes with secondary constrictions. Minor structural alterations of chromosomes have probably played the most important role in the evolution of genus and species rather than polyploidy and aneuploidy.
6 citations
TL;DR: The arguments presented here support the adjacent location of somatic homologous chromosomes in the nucleus, suggesting their adjacent or opposite location in somatic arrangement.
Abstract: Two different mitotic spatial models (Lavania & Sharma, Biosystems 14: 171–178, 1981: Ashley & Pocock, Genetica 55: 161–169, 1981) for the arrangement of the chromosomes in the nucleus are analysed for the sake of comparison and assessment. In general, the two models propose nearly the same orientation regarding chromosomal organization. However, they differ with respect to the position of homologous chromosomes, suggesting respectively their adjacent or opposite location in somatic arrangement. The two proposals have been analysed in the light of experimental evidence as well as organizational interpretations. The arguments presented here support the adjacent location of somatic homologous chromosomes.
4 citations
TL;DR: Non-random arrangement of interphase chromosomes and organization of a structure like centromeric ring for maintaining the spatial relationship have been demonstrated.
Abstract: The C-bands of Lathyrus sphaericus are present in the centromeric region of all the 14 chromosomes and the satellited region of the nucleolar pair. Orientation of interphase chromosomes is non-random and late anaphase arrangement of chromosomes is maintained up to next late prophase through interphase. At interphase, centromeric regions form a ring-like arrangement towards one pole and chromosomes remain polarised. The chromosomes may be present singly or 2-3 centro-meres may associate to form 5-7 centromeric masses. Regularity of spatial relationshipof chromosomes throughout the division cycle is indicated. Non-random arrangement of interphase chromosomes and organization of a structure like centromeric ring for maintaining the spatial relationship have been demonstrated.
1 citations