Fortress repair in the social aphid species Pemphigus spyrothecae

Nest repair is a vital element in the cooperative brood care that is a distinctive feature of eusocial animals. We investigated the repair role of individuals of the social aphid Pemphigus spyrothecae by prematurely opening their gall by cutting a hole of the same size and position as a natural opening. This resulted in increased mortality from predation. No subsequent responsive shift towards increased investment in soldiers was detected. However, repair of the holes by compensatory regrowth from undamaged adjoining areas of the gall was observed in 97.5% of the experimental galls that were protected from predation. Subsequent experiments confirmed that the aphids were responsible for this repair, with soldiers likely to be the major agents. Active maintenance of the integrity of the gall represents another altruistic task for which soldiers are predominantly responsible and indicates that social complexity in the order Hemiptera is greater than previously assumed.     

Antibody to the nonapeptide Glu-Glu-Glu-Glu-Tyr-Met-Pro-Met-Glu is specific for polyoma middle T antigen and inhibits in vitro kinase activity

Middle T antigen of polyoma virus has an associated tyrosine kinase activity which phosphorylates tyrosine residue 315 on middle T in immunoprecipitates. A peptide representing the sequence of middle T from residue 311 to 319 has been synthesized. This peptide acts as a weak inhibitor of the kinase reaction. An antiserum has been raised against this peptide after conjugation to bovine serum albumin. The antibody is middle T-specific. Middle T antigen precipitated by this serum is largely inactive in the kinase reaction. Dissociation of the immune complex with peptide releases middle T in a kinase-active form.     

A high yield method for the isolation of sheep's liver cathepsin L

A method, giving twice the yield of the previous method, for the isolation of sheep's liver cathepsin L is described. The method uses three phase partitioning (TPP) in t-butanol/water/ammonium sulphate mixtures, followed by two chromatographic steps, at different pH values, in a single column of S-Sepharose.     

Analyses of steroids in saliva using highly selective mass spectrometric techniques

Highly selective techniques of gas chromatography mass spectrometry have been used in the unequivocal identification of salivary steroids at concentrations ranging from 20 pg ml-1 to 20 ng ml-1. Oestradiol-17 beta, for example, has been identified in pregnancy saliva by gas chromatography high resolution mass spectrometry selected ion monitoring of the bis-TMS ether and by gas chromatography mass spectrometry metastable peak monitoring of the bis-tert-butyldimethylsilyl ether. Dehydroepiandrosterone sulphate has been identified in saliva, following enzymic hydrolysis, by gas chromatography high resolution mass spectrometry selected ion monitoring of the tert-butyldimethylsilyl ether and methyloxime tert-butyldimethylsilyl ether. These initial analyses have been designed to guide the development of routine immunoassay procedures which may subsequently be validated by comparison with reference gas chromatographic mass spectrometric methods.     

A chemoattractant receptor on macrophages exists in two affinity states regulated by guanine nucleotides

The binding characteristics of the oligopeptide chemoattractant receptor on guinea pig macrophages and macrophage membrane preparations were characterized using detailed binding studies and computer analysis. Viable macrophages bound the radiolabeled chemoattractant N-formyl-methionyl-leucyl-[3H]phenylalanine with single dissociation constant (KD) of 18.4 +/- 4.6 nM with 15,300 +/- 1,800 sites per cell. Binding data from membrane preparations indicated the presence of two classes of binding sites with KD of 1.5 +/- 0.4 nM and 25.5 +/- 11.0 nM. Approximately 23% of the receptors were in the high affinity state. In the presence of added guanine nucleotide di- or triphosphates, the high affinity receptors in the membrane preparations were converted to low affinity states with no change in the total receptor number. Nonhydrolyzable derivatives of GTP were most potent in converting the receptor from its high to low affinity state. These data suggest that the affinity state of the oligopeptide chemoattractant receptor in macrophages is regulated by guanine nucleotides and GTPase, implying that the transduction mechanisms of this receptor may be controlled by a guanine nucleotide regulatory unit.