Desiccation tolerance of spermatozoa dried at ambient temperature: production of fetal mice

Long-term preservation of mouse sperm by desiccation is economically and logistically attractive. The current investigation is a feasibility study of the preservation of mouse sperm by convective drying in an inert gas (nitrogen). Mouse sperm from the B6D2F1 strain isolated in an EGTA-supplemented Tris-HCl buffer were dried using three different drying rates and were stored for 18-24 h at 4 degrees C. The mean final moisture content was <5% for all the protocols. After intracytoplasmic sperm injection (ICSI), the mean blastocyst formation rates were 64%, 58%, and 35% using the rapid-, moderate-, and slow-drying protocols, respectively. The slow-drying protocol resulted in a rate of development significantly lower than that observed using rapid- and moderate-drying protocols and indicated that a slower drying rate may be detrimental to the DNA integrity of mouse sperm. The transfer of 85 two- or four-cell embryos that were produced using rapidly desiccated sperm resulted in 11 fetuses (13%) on Day 15 compared with the production of 34 fetuses (40%) produced using the transfer of 86 two- or four-cell embryos that were produced using fresh sperm (P < 0.05). The results demonstrate the feasibility of using a convective drying protocol for the successful desiccation of mouse sperm and identifies some of the important parameters required for optimization of the procedure.     

Optimization of cyclodextrin glycosyltransferase production from Klebsiella pneumoniae AS-22 in batch, fed-batch, and continuous cultures

Production of a novel cyclodextrin glycosyltransferase (CGTase) from Klebsiella pneumoniae AS-22 strain, which converts starch predominantly to alpha-CD at high conversion yields, in batch, fed-batch, and continuous cultures, is presented. In batch fermentations, optimization of different operating parameters such as temperature, pH, agitation speed, and carbon-source concentration resulted in more than 6-fold increase in CGTase activity. The enzyme production was further improved by two fed-batch approaches. First, using glucose-based feed to increase cell density, followed by starch-based feed to induce enzyme production, resulted in high cell density of 76 g dry cell weight/L, although the CGTase production was low. Using the second approach of a single dextrin-based feed, 20-fold higher CGTase was produced compared to that in batch fermentations with media containing tapioca starch. In continuous operation, more than 8-fold increase in volumetric CGTase productivity was obtained using dextrin-based media compared to that in batch culture using starch-based media.     

Signalling pathways of the TNF superfamily: a double-edged sword

Two different tumour-necrosis factors (TNFs), first isolated in 1984, were found to be cytotoxic to tumour cells and to induce tumour regression in mice. Research during the past two decades has shown the existence of a superfamily of TNF proteins consisting of 19 members that signal through 29 receptors. These ligands, while regulating normal functions such as immune responses, haematopoiesis and morphogenesis, have also been implicated in tumorigenesis, transplant rejection, septic shock, viral replication, bone resorption, rheumatoid arthritis and diabetes; so indicating their role as 'double-edged swords'. These cytokines either induce cellular proliferation, survival, differentiation or apoptosis. Blockers of TNF have been approved for human use in treating TNF-linked autoimmune diseases in the United States and other countries.     

Lipase production from an alkalophilic yeast sp. by solid state fermentation

The present investigation has been carried out with the aim to produce lipase from an alkalophilic yeast species by solid state fermentation using rice and wheat brans as alternative cheap solid substrates.     

Isolation and identification of a mevalonolactone by-product formed during the assay for 3-hydroxy-3-methylglutaryl coenzyme a reductase activity

A mevalonolactone by-product formed during the assay for 3-hydroxy-3-methylglutaryl-CoA reductase activity is isolated and proof of its structure is provided from gas chromatographic, NMR and mass spectrometric studies.