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Biomedical subjects

U C Lavania

Publications and source records attributed to U C Lavania.

4 recordsLinked to original sources

Duration of cell cycle, onset of S phase and induced mitotic synchronisation in seeds of opium poppy, Papaver somniferum L.

Duration of mitotic cell cycle and its component phases in root-tip meristem of P. somniferum was determined following autoradiographic detection of mitotic rythms during the traverse of cell cycle. The mitotic cycle time thus estimated was found to be 12.6h of which the distribution of component phases was G1 = 1.75 h, S = 6.3 h, G2 = 3.75 h and division phase (M) = 0.8 h. Dry seeds were metabolically activated by soaking in water to show that the first batch amongst the asynchronous population of cells in the seeds enters into S phase after 18 h of such soaking at 16 degrees C. Mitotic synchrony to the tune of 80% could be realised when such presoaked seeds were administered 5 mMole hydroxyurea for 20 h at 16 degrees C.

Cell Cycle

An interphase model for mitotic chromosome organization in eukaryota.

A model for the spatial relationship of the arrangement of the chromosomes in the nucleus in eukaryota is presented. Evidence is derived from light and electron microscopic studies, application of autoradiographic and banding techniques; on the organization, structure and behaviour of chromosomes during interphase and other stages of cell cycle. This model visualizes the entire chromosomal DNA as a single uninemic multirepliconic continuum where the chromosomes with their centromeres and telomeres have a predetermined arrangement among themselves as well as in relation to the nucleolus and nuclear membrane. This orderly arrangement is presumably maintained through interchromosomal connections. The impact of this model on the interpretation of various cytogenetic phenomena is discussed.

Animals

Trypsin-orcein banding in plant chromosomes.

A convenient and quick method using trypsin-orcein for banding plant chromosomes (O-banding) is suggested. The technique is directly applicable to meristematic tissues (e.g. root tips) and involves the treatment of root tips with 1-2% solution of trypsin either in buffer or in 0.5 N HCl for 5-10 minutes at 37 C or for 30-60 minutes near 0 C followed by staining with 1.5% acetic orcein: 1 N HCl (19:1). Dark staining bands are reproducible and species specific. These bands possibly represent specific DNA-protein-dye interaction.

Chromosome Banding