Volume 85, Issue 1
January 1977, pages 1-41
pp 1-12 January 1977
A potent and specific antiserum was raised in rabbits by injecting a single cell suspension of thymocytes of the lizard,Calotes versicolor. Rabbit anti-Calotes thymocyte serum (ATS) was characterizedin vitro by using cytotoxicity assay and quantitative absorption analysis. The cytolytic activity of ATS was always higher towards thymocytes than towards lymphoid cells of spleen, bone-marrow and peripheral blood. Various absorption experiments indicate the existence of two antigens among thymocytes—one distinct for thymocytes and thymus derived cells and another, common to lymphocytes. Further, thymus-brain antigenic correlation has been demonstrated in this reptilian species. TheCalotes complement is less efficient than that of guinea pig in mediating the cytolysis of target cells by ATS. Further, ATS did not have cytotoxic effect on antibody producing cells. The significance of these findings has been discussed with reference to the dichotomy of lymphoid systems at this phylogenetic level.
pp 13-20 January 1977
pp 21-24 January 1977
The karyotype and meiosis in a tetraploid population ofFimbristylis falcata (Vahl) Kunth (2n=44) have been studied. The chromosomal data reveal the presence of four essentially similar genomes. In the light of available data it is concluded that the taxon is a natural autotetraploid.
pp 25-33 January 1977
The role of the thymus in antibody response to sheep erythrocytes (SRBC) was investigated in the lizard,Calotes versicolor, by utilizing the experimental models of adult thymectomy and anti-thymocyte serum (ATS) treatment. When thymectomized lizards were treated with high dose regimen of ATS, plaque-forming cell (PFC) response to SRBC was abrogated; however, this response was not altered by the low dose. A definite recovery of anti-SRBC response after ATS treatment occurred in the presence of the thymus. On the other hand the PFC response to SRBC was enhanced one month after adult thymectomy and after low dose ATS treatment. Both low and high doses of normal rabbit serum suppressed the immune response to SRBC and it is suggested that this suppression might be due to antigenic competition.
These results indicate that (i) anti-SRBC response is thymus dependent and (ii) there are two kinds of thymus derived cells: one ‘helper’ collaborating in anti-SRBC response and another ‘regulator’ governing the magnitude of the response which is involved in antigenic competition. The phylogenetic status on the dual role of the thymus in immune functions has been discussed.
pp 34-41 January 1977
The structure and development of the root nodule ofCasuarina equisetifolia have been studied.