Use of oven-dried blood for in vitro feeding of tsetse flies

Comparison of the survival, fecundity and offspring size of Glossina palpalis palpalis females fed reconstituted oven-dried blood, fresh, frozen/thawed, or reconstituted freeze-dried blood showed that oven-drying at 45 degrees C does not diminish the nutritional quality of blood. The significance of this finding is discussed with a view to optimizing costs and conditions of blood-diet storage and transportation in the context of mass-rearing of tsetse flies.     

Optically active benzo[c]phenanthrene diol epoxides bind extensively to adenine in DNA

Reactions of diol epoxide metabolites of carcinogenic polycyclic aromatic hydrocarbons with DNA are thought to initiate the carcinogenic process. Although formation of a benzo[a]pyrene (BaP) diol epoxide-deoxyguanosine adduct has been held responsible for biological activity, the more potent carcinogen, 7,12-dimethylbenz[a]anthracene (DMBA) binds extensively to deoxyadenosine residues in DNA, suggesting that hydrocarbon carcinogen-deoxyadenosine adducts may be instrumental in tumour initiation. Because the bay region diol epoxides of benzo[c]phenanthrene (BcPh) are very active tumour initiators, and the relative activities of the four configurationally isomeric 3,4-diol 1,2-epoxides (Fig. 1) are known, we examined their reactions with DNA. Each BcPh diol epoxide isomer exhibits a remarkable preference for covalent binding to DNA over hydrolysis, each yields a unique distribution of products with the nucleosides of DNA and each reacts extensively with deoxyadenosine residues in DNA. The relative tumour initiating activities of these stereoisomers is best reflected by the relative yields of one of the deoxyadenosine adducts formed.     

The need for national HIV databases

Researchers and public health officials involved in surveying and forecasting the course of the HIV epidemic require complete and unfiltered information from many sources. Governments should respond by establishing national HIV databases.     

High molecular transport proteins for JH-III in insect hemolymph

Summary Using two independent techniques, ultracentrifugation in a KBr-gradient, and native pore polyacrylamide gel electrophoresis in combination with [³H]-epoxyfarnesyldiazoacetate photoaffinity labeling, we showed that in the hemolymph ofPeriplaneta americana, and probably also inLeptinotarsa decemlineata JH-III binds to the lipophorin, whereas inLocusta migratoria JH-III binds to a different protein.     

Recognition of myelin-associated glycoprotein by the monoclonal antibody HNK-1

Myelin-associated glycoprotein (MAG) is a quantitatively minor component in both peripheral and central myelin sheaths that is thought to have a role in cell-cell interactions within the nervous system. We show here that a mouse monoclonal antibody, HNK-1, which is directed against human natural killer cells also recognizes an antigenic determinant of human central and peripheral nervous system white matter by immunoperoxidase staining of tissue sections. Immunoblot analysis of myelin proteins and purified extracted MAG indicates that the antigen recognized is MAG.     

Phorbol ester and diacylglycerol mimic growth factors in raising cytoplasmic pH

There is now good evidence that cytoplasmic pH (pHi) may have an important role in the metabolic activation of quiescent cells. In particular, growth stimulation of mammalian fibroblasts leads to a rapid increase in pHi (refs 3-6), due to activation of a Na+/H+ exchanger in the plasma membrane, and this alkalinization is necessary for the initiation of DNA synthesis. However, the mechanism by which mitogens activate the Na+/H+ exchanger to raise pHi is not known, although an increase in cytoplasmic free Ca2+ ([Ca2+]i) has been postulated as the primary trigger. We now present data suggesting that the Na+/H+ exchanger is set in motion through protein kinase C, a phospholipid- and Ca2+-dependent enzyme normally activated by diacylglycerol produced from inositol phospholipids in response to external stimuli. Using newly developed pH microelectrodes and fluorimetric techniques, we show that a tumour promoting phorbol ester and synthetic diacylglycerol, both potent activators of kinase C (refs 12-15), mimic the action of mitogens in rapidly elevating pHi in different cell types. Furthermore, we demonstrate that, contrary to previous views, an early rise in [Ca2+]i is not essential for the activation of Na+/H+ exchange and the resultant increase in pHi. Finally, we suggest that an alkaline pHi shift, mediated by Na+/H+ exchange, may be a common signal in the action of those hormones which elicit the breakdown of inositol phospholipids.     

The Tetrahymena ribozyme acts like an RNA restriction endonuclease

A shortened form of the Tetrahymena self-splicing ribosomal RNA intervening sequence acts as an endoribonuclease, catalysing the cleavage of large RNA molecules by a mechanism involving guanosine transfer. The sequence specificity approaches that of the DNA restriction endonucleases. Site-specific mutagenesis of the enzyme active site alters the substrate sequence specificity in a predictable manner, so that endoribonucleases can be synthesized to cut at a variety of tetranucleotide sequences.     

Loss of a Harvey ras allele in sporadic Wilms' tumour

Genomic changes within chromosome band 11p13 appear to have a role in the initiation of Wilms' tumour. The human Harvey ras oncogene, c-Ha-ras 1, has been located by Jhanwar et al. immediately adjacent to this region at band 11p14 .1, although several groups have assigned the gene more distally at band 11p15 . We have examined tumour DNA from two cases of sporadic Wilms' tumour, and report here that in both cases one of the two constitutional c-Ha-ras 1 alleles was absent. One tumour had a reciprocal translocation between the short arm of chromosome 11 (at band 11p13), and the long arm of chromosome 12, with no visible loss of chromosomal material. The loss of a c-Ha-ras 1 allele in association with this translocation indicates that a submicroscopic deletion had occurred. The resulting hemizygosity may have had a role in tumour initiation. Our results indicate that the c-Ha-ras 1 gene and the 'Wilms' tumour locus' may be in close proximity. It would, therefore, be premature to exclude the possibility that these two sites are functionally related.     

Plasma catecholamines in children

Summary Plasma catecholamine concentrations in 46 children of various ages were determined by a sensitive radioenzymatic assay. Noradrenaline levels were found to be in the same range as in adults, whereas adrenaline levels in a few of the children were abnormally high.