Structure, expression and divergence of T-cell receptor beta-chain variable regions

Analysis of three new T-cell receptor beta-chain variable regions together with those in the literature indicates that they have both remarkable similarities and differences with those of immunoglobulin. Less than 10 V regions appear to predominate in the thymus. V beta sequences are much more heterogeneous at the amino acid level than are immunoglobulin V regions and they appear to diverge between species much more quickly, apparently the result of additional hypervariable regions. Three of these putative new hypervariable regions lie outside of the classical immunoglobulin binding site, an indication that important interactions may be occurring in these regions with polymorphic MHC determinants.     

Contradictory differential staining results with Coomassie Brilliant Blue and silver carbonate on sister chromatids

Summary Coomassie Brilliant Blue, and silver stain, are used in electrophoretic gels to identify polypeptides. The relative staining intensity has been taken as indicating a quantitative difference between proteins. However, when these 2 stains were applied to 2 identically pretreated chromosome preparations, contradictory staining results were obtained.Acknowledgment. This work is supported under the auspices of the National Science Council, Republic of China.     

Natural hybridization inDrosophila

Summary Although at least 159 cases of interspecific hybridization between closely related species ofDrosophila have been obtained under laboratory conditions, only 7 cases of natural interspecific hybridization have been recorded. We report yet another case, concerningD. malerkotliana andD. bipectinata.Thanks are due to the University Grants Commission for supporting the research project of J.P.G. and to the Head of the Department for laboratory facilities.     

The effect of chloroquine upon the developing lens

Summary Applied to the developing lens of the 14-day-old chick embryo, in organ culture conditions, chloquine prevented the elongation of the primary lens fibres, destroyed the equatorial ones and provoked vacuolisation and/or destruction in the epithelial cells.This work was supported by a grant from the office of the Chief Scientist, Ministry of Health, Israel     

Cholinergic-rich brain transplants reverse alcohol-induced memory deficits

Alcohol-induced memory impairment in man has been attributed to deficiencies in subcortical noradrenergic and cholinergic systems, as well as to damage in midbrain structures. Korsakoff's psychosis, a disease in which alcohol poisoning causes apparently irreversible memory defects, is characterized by lesions in cholinergic and noradrenergic nuclei and by a decrease in the activity of choline acetyltransferase (ChAT) and the content of noradrenaline (NA) in forebrain areas such as cerebral cortex and hippocampus, innervated by these nuclei. Prolonged intake of ethanol in rodents similarly produces signs of noradrenergic and cholinergic deafferentation in the cortex and hippocampus, as well as persistent memory deficits. To test whether alcohol-induced memory impairments depend on cholinergic deafferentation, we transplanted cholinergic-rich fetal basal forebrain cell suspensions into the cortex and hippocampus of alcohol-treated rats. The substantial and persistent memory losses produced in our rats by ethanol intake were associated with an impairment of cholinergic function, and were reversed by cholinergic-rich transplants into cortex and hippocampus.     

Fibronectin receptor structures in the VLA family of heterodimers

Multiple cell surface proteins of relative molecular mass 115,000-155,000 (Mr 115K-155K) have been implicated as receptors mediating adhesion to extracellular matrix proteins. But the organization and relatedness of these peptides has remained unclear. In separate studies, the 'very late antigens' VLA-1 (Mr 210K/130K) and VLA-2 (Mr 160K/130K) were initially characterized as surface heterodimers appearing 2-4 weeks after in vitro stimulation of human T cells. Three more VLA heterodimers have since been discovered, which, like VLA-1 and VLA-2, are each composed of unique alpha-subunits in association with a common 130K beta subunit. This paper shows that the common VLA beta-subunit is equivalent to subunits found in structures with known fibronectin and laminin receptor activity, and that VLA-3 and VLA-5 are similar or identical to these previously defined receptors for adhesion molecules. Antibody blocking studies confirmed that at least some of the widely distributed VLA proteins of previously unknown function are involved in cell adhesion to fibronectin and laminin. We suggest that the VLA family of receptors may provide cells with multiple independent substrate adhesion capabilities.