Synthesis and characterization of water soluble biomimetic chitosans for bone and cartilage tissue regeneration.

Chitosan, a polysaccharide derived from the exoskeleton of crustaceans, insects, the cell walls of fungi, the radulas of mollusks and the internal shells of cephalopods, has been shown to promote osteogenesis. Arginine functionalized chitosan, a water soluble derivative of chitosan, was successfully sulfated with a degree of sulfur incorporation of up to 9% with substitution at the 2-N position. This degree of sulfation replicated those of naturally occurring growth factor binding glycosaminoglycans.

Essential role of one-carbon metabolism and Gcn4p and Bas1p transcriptional regulators during adaptation to anaerobic growth of Saccharomyces cerevisiae.

The transcriptional activator Gcn4p is considered the master regulator of amino acid metabolism in Saccharomyces cerevisiae and is required for the transcriptional response to amino acid starvation. Here it is shown that Gcn4p plays a previously undescribed role in regulating adaptation to anaerobic growth. A gcn4 mutant exhibited a highly extended lag phase after a shift to anaerobiosis that was the result of l-serine depletion.

Effect of medium properties and additives on antibody stability and accumulation in suspended plant cell cultures.

Factors affecting antibody accumulation and stability were investigated in transgenic plant cell cultures. Whereas IgG(1) antibody was stably maintained in media used for animal cell culture, there was a rapid loss over a period of 1-2 h of antibody added to sterile plant culture media. Antibody stability in Gamborg's B5 medium was improved in the absence of Mn.