Single-strand conformation polymorphism analysis of human decorin, biglycan and fibromodulin cDNAs.

The coding regions of the human decorin, biglycan and fibromodulin cDNAs have been examined utilizing the method of single-strand conformation polymorphism analysis. Analysis of total RNA from a group of eight human skin fibroblast cell lines did not detect any sequence variations in the decorin cDNA. In contrast, the analysis detected three sequence variations in the biglycan cDNA and one in the fibromodulin cDNA from the same group of cell lines. For the biglycan cDNA, one variation involved a position in the 5'-untranslated region, while the other two affected the wobble bases of triples encoding serine residues 10 and 143 of the mature core protein. For the fibromodulin cDNA, the variation involved the wobble position of the codon for glutamic acid residue 61 of the putative mature core protein. Single-strand conformation polymorphism analysis of these proteoglycan cDNAs was also applied to study patients exhibiting a variety of connective tissue pathologies, including chondrodysplasia punctata, Desbuquois syndrome, Dyggve-Melchior-Clausen syndrome, dyssegmental dysplasia, Ehlers-Danlos syndrome types I and III, Ellis van Creveld syndrome and thanatophoric dysplasia, though no additional sequence variations were detected.

Construction of an Acid-Tolerant Rhizobium leguminosarum Biovar Trifolii Strain with Enhanced Capacity for Nitrogen Fixation.

Strain ANU1173 is an acid-tolerant Rhizobium leguminosarum biovar trifolii strain that is able to nodulate subterranean clover plants growing in agar culture at pH 4.4 At pH 6.5, its symbiotic effectiveness in association with Trifolium subterraneum cv. Mt. Barker was 80% relative to that of strain ANU794, a Sm derivative of the commercial inoculant R. leguminosarum bv. trifolii TA1. Strain ANU1173 contained four indigenous megaplasmids, the smallest of these being the symbiotic (Sym) plasmid. The critical pH requirement for growth of strain ANU1173 in laboratory media was shown not to be associated with this plasmid. When the Sym plasmid of strain ANU1173(pSym-1173) was mobilized into a Nod strain of R. leguminosarum bv. viciae, the plasmid conferred to the transconjugant a level of symbiotic effectiveness in association with T. subterraneum that was similar to that observed with ANU1173. The symbiotic effectiveness of strain ANU1173 was improved by first curing pSym-1173 (generating strain ANU1184) and replacing it with another R. leguminosarum bv. trifolii Sym plasmid, pBR1AN. Subterranean clover plants inoculated with strain ANU1184 (pBR1AN) exhibited a 35 or 53% increase in acetylene reduction activity and a 20 or 17% increase in dry weight when grown at pH 6.5 and pH 4.4, respectively, compared with plants inoculated with strain ANU1173 and grown under the same pH conditions. It was further shown that pBR1AN was stably maintained in strain ANU1184 under free-living and symbiotic conditions. These results indicate that it is possible to construct an acid-tolerant strain of R. leguminosarum bv. trifolii with an enhanced capacity for nitrogen fixation.