An outbreak of foot-and-mouth disease in Indian elephants (Ellphas maximus)

Type O virus has been isolated from a natural outbreak of foot-and-mouth in Indian elephant. The history, symptoms and epizootology of this disease in these animals have also been described.

Studies on the maturation of thymus stem cells. The effects of catecholamines, histamine and peptide hormones on the expression of T cell alloantigens

Studies have been performed in order to investigate the effects of catecholamines. histamine, peptide hormones and various other agents known to increase cellular adenosine 3':5'-cyclic monophosphate (cAMP) levels on the expression of Thy-1 and TL antigens on 14-day fetal thymic stem cells. It has been shown that the proportions of Thy-1 and TL positive cells, as detected by dye exclusion cytotoxicity tests, can be significantly increased by some of these agents and that these effects may be inhibited by beta adrenergic and H2 antagonists. The value of these tests as a means for studying normal thymic stem cell maturation and for investigating T cell deficiency is discussed.

Studies on the effect of various agents on the maturation of thymus stem cells

Experiments were carried out on 14-day fetal mouse thymic stem cells which were treated with agents known to increase cellular cAMP levels for a period of 90 min at 37 degrees C. When compared to controls, a high proportion of treated stem cells were found to develop Thy-1 (theta) antigen as indicated by dye exclusion tests using anti-Thy-1 serum and complement.

Desynapsis and the blockage of meiosis in Pennisetum orientale Rich

Meiotic behaviour of a desynaptic plant of Pennisetum orientale Rich., which seems to have arisen through spontaneous gene mutation/s, is recorded. The plant showed an extremely rare type of desynapsis in which the precocious falling-apart of the homologous chromosomes was accompanied by the blockage of the meiotic course from metaphase I onwards. Different factors which may have led to the failure of chromosome synapsis and to the blockage of the meiotic division are discussed. The possibility of the participation of different enzymes in the initiation and continued progress of chromosome synapsis as well as for the different meiotic steps is considered. It has been inferred that the absence or later inactivation of these genetically-controlled enzymes might have resulted in the meiotic abnormalities observed in the present material. Another plausible regulatory mechanism based on the existence of a switch - through gene-repressing effect of histones - has been hypothesized and its possible evolutionary significance indicated.