A single micromanipulated stem cell gives rise to multiple T-cell receptor gene rearrangements in the thymus in vitro

The extensive range of specificities of T-cell receptors is generated, as for immunoglobulins, by rearrangement of genetic information. Much valuable information about rearrangement processes has been inferred by comparing DNA from (monoclonal) lymphoid lines with germ-line DNA and, for B cells, from rearrangements in some Abelson murine leukaemia virus-transformed cell lines. However, because it is difficult to isolate and grow precursor populations, it has not proved possible to study rearrangements occurring in normal untransformed cells in vitro. Here we show that a single T-cell precursor colonizing an alymphoid thymus lobe in organ culture can generate multiple receptor beta-chain gene rearrangements. These observations provide unequivocal evidence for the intra-thymic diversification of the T-cell repertoire. They also offer the possibility of investigating rearrangement and its control in the clonal progeny of a single normal T-cell precursor without the perturbations involved in the use of viral transformation or the production of T-cell hybridomas.     

T cell and T cell subset determination in normal peripheral blood: comparison of the indirect immunofluorescence and lymphocytotoxicity techniques

We compared a simple complement-dependent lymphocytotoxicity test with a widely used indirect immunofluorescence procedure to enumerate total T, T helper, and T suppressor lymphocytes in normal blood samples. Results with the two techniques were closely similar.     

The chromosomes of four species of Falconiformes

Summary Leucocyte cultures were used in four species of Falconiformes for the purpose of karyotypic sex determination and the establishment of a breeding pair. The Andean condor has 80 Guiana eagle 54, Crane hawk 66, and Turkey vulture 76 chromosomes with readily distinguished ZW elements in the female.Our cordial thanks are extended toA. Risser, Ph. D. Assistant Curator of Birds, San Diego Zoo;Warren Thomas, D.V.M., Director, Los Angeles Zoo for their cooperation and assistance in the collection of blood samples for chromosome study. We are also grateful toK. Benirschke, M.D., Director of Research, San Diego Zoo for his kind assistance.     

Changes in the activities of protein kinase modulators in the cerebellum of mice due to ethanol, caffeine, or phenobarbital administration.

Decreased activities of both the inhibitory modulator of adenosine 3':5'-monophosphate (cAMP)-dependent protein kinase (A-PK) as well as the stimulatory modulator of guanosine 3':5'-monophosphate (cGMP)-dependent protein kinase (G-PK) from the mouse cerebellum were noted due to the administration of excessive doses of ethanol, caffeine, and phenobarbital for up to 28 days. The dose-dependent of the inhibition of A-PK or the stimulation of G-PK was observed as a function of the amount of protein kinase modulators in the cerebellum of mice receiving different doses of ethanol.