Meristic differences between two conspecific fish populations in Australian salt lakes

Two meristic characters were found to be significantly different in a species of Taeniomembras (Pisces: Atherinidae) from two highly saline inland lakes in South Australia. It is suggested that the differences were induced by salinity differences between the lakes.     

High productivity ethanol fermentations with Zymomonas mobilis using continuous cell recycle

Summary Cell recycle studies have been carried out with a strain of Zymomonas mobilis selected for its improved ethanol tolerance and faster rates of glucose uptake and ethanol production. As part of the investigation a capilliary cross-flow microfiltration unit with polyamide membranes has been evaluated in view of its potential advantages (low cost and ability to withstand repeated cleaning with caustic soda). The results demonstrate that ethanol concentrations of 60–65g/l can be sustained at productivities ranging from 120–200g/l/h.     

Headgroup dynamics of an integral membrane glycoprotein.

Glycophorin, an integral membrane glycoprotein known to be a receptor for several lectins, has been spin labelled specifically on headgroup terminal sugars. The labelled derivative has been studied in solution and also in various model membranes in an attempt to determine the factors which control headgroup dynamics. Under conditions which mimic those in a living cell the oligosaccharide chains show a uniform, relatively high freedom of motion, with individual sugar correlation times on the order of 6 × 10^?10 sec to 8 × 10^?10 sec depending upon the extent of glycoprotein headgroup involvement with other glycocalyx components. They exhibit no detectable occupancy of lipid or protein hydrophobic domains. Oligosaccharide dynamics are insensitive to factors which act upon that portion of the polypeptide backbone which inserts into the membrane, however a specific recognition event markedly reduces terminal sugar mobility.     

Protein disulphide isomerase is required for signal peptide peptidase-mediated protein degradation

The human cytomegalovirus glycoprotein US2 induces dislocation of MHC class I heavy chains from the endoplasmic reticulum (ER) into the cytosol and targets them for proteasomal degradation. Signal peptide peptidase (SPP) has been shown to be integral for US2-induced dislocation of MHC class I heavy chains although its mechanism of action remains poorly understood. Here, we show that knockdown of protein disulphide isomerase (PDI) by RNA-mediated interference inhibited the degradation of MHC class I molecules catalysed by US2 but not by its functional homolog US11. Overexpression of the substrate-binding mutant of PDI, but not the catalytically inactive mutant, dominant-negatively inhibited US2-mediated dislocation of MHC class I molecules by preventing their release from US2. Furthermore, PDI associated with SPP independently of US2 and knockdown of PDI inhibited SPP-mediated degradation of CD3δ but not Derlin-1-dependent degradation of CFTR DeltaF508. Together, our data suggest that PDI is a component of the SPP-mediated ER-associated degradation machinery.