Environmental control of protein export of Bacillus licheniformis NCIB 6346 reveals two types of extracellular proteins

Teichuronic acid was the major anionic polymer of Bacillus licheniformis NCIB 6346 durign phosphate-limited (P-limited) growth in the chemostat. This polymer was also present in significant quantities when B. licheniformis was grown under carbon-limited (C-limited) or magnesium-limited (Mg-limited) conditions where teichoic acid predominated in the cell wall. However, the cell wall composition was not of significance in protein export and the parameters for the excretion process were found to be environmental. In particular, two types of extracellular proteins were identified: the first type of enzyme, penicillinase, was only weakly catabolite repressed; was maximally synthesized and secreted during P-limited growth; was unaffected by growth in high Na⁺ media but its production was inhibited by gramicidin. The second type of enzyme, -amylase, was strongly catabolite repressed and its export was markedly inhibited during P-limited growth or in the presence of Na⁺ or gramicidin. It is noteworthy that the penicillinase carries a glyceride-cysteine modification at its N-terminus whilst the -amylase does not.     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Protonmotive force driven 6-deoxyglucose uptake by the oral pathogen,Streptococcus mutans Ingbritt

Streptococcus mutans Ingbritt was grown in glucose-excess continuous culture to repress the glucose phosphoenolpyruvate phosphotransferase system (PTS) and allow investigation of the alternative glucose process using the non-PTS substrate, (³H) 6-deoxyglucose. After correcting for non-specific adsorption to inactivated cells, the radiolabelled glucose analogue was found to be concentrated approximately 4.3-fold intracellularly by bacteria incubated in 100 mM Tris-citrate buffer, pH 7.0. Mercaptoethanol or KCl enhanced 6-deoxyglucose uptake, enabling it to be concentrated internally by at least 8-fold, but NaCl was inhibitory to its transport. Initial uptake was antagonised by glucose but not 2-deoxyglucose. Evidence that 6-deoxyglucose transport was driven by protonmotive force (p) was obtained by inhibiting its uptake with the protonophores, 2,4-dinitrophenol, carbonylcyanide m-chlorophenylhydrazine, gramicidin and nigericin, and the electrical potential difference () dissipator, KSCN. The membrane ATPase inhibitor, N,N¹-dicyclohexyl carbodiimide, also reduced 6-deoxyglucose uptake as did 100 mM lactate. In combination, these two inhibitors completely abolished 6-deoxyglucose transport. This suggests that the driving force for 6-deoxyglucose uptake is electrogenic, involving both the transmembrane pH gradient (pH) and . ATP hydrolysis, catalysed by the ATPase, and lactate excretion might be important contributors to pH.Abbreviations DNP 2,4-dinitrophenol - CCCP carbonylcyanide m-chlorophenylhydrazone - DCCD N,N¹-dicyclohyxyl carbodiimide - p protonmotive force - pH transmembrane pH gradient - transmembrane electrical potential difference     

Fetal ultrasonography: Normal biometric ranges in the baboon (Papio hamadryas)

Normal biometric ranges for fetal growth in a captive breeding baboon (Papio hamadryas) colony are described. Measurements include crown-rump length, biparietal diameter, binocular distance, head circumference, abdominal circumference, femur length and amniotic fluid index. The pattern of fetal growth is compared with other baboon subspecies and man. The uses and limitations of such data for breeding colony management and optimum utilisation of experimentally derived data are discussed.     

Approaches to breeding for salinity tolerance - a case study on Porteresia coarctata

Cereals are the world's major source of food for human nutrition. Among these, rice (Oryza sativa) is the most prominent and represents the staple diet for more than two-fifths (2.4 billion) of the world's population, making it the most important food crop of the developing world (Anon., 2000a). Rice production in vast stretches of coastal areas is hampered due to high soil salinity. This is because rice is a glycophyte and it does not grow well under saline conditions. In order to increase rice production in these areas there is a need to develop rice varieties suited to saline environments. Research has shown that Porteresia coarctata, a highly salt tolerant wild relative of rice growing in estuarine soils, is an important material for transferring salt tolerant characteristics to rice. It is quite possible that Porteresia may be used as a parent for evolving better and truly salt resistant varieties. The inadequate results and the difficulties associated with conventional breeding techniques necessitate the use of the tools of crop biotechnology in unravelling some of the characteristics of Porteresia that have been highlighted in this report. In view of the limited resources available for increasing salinity tolerance to the breeders to wild rice germplasm, Porteresia is undoubtedly one of the key source species for elevating salinity tolerance in cultivated rice.