The method of localized mutagenesis was applied to obtain mutants of Streptomyces fradiae producing higher amounts of tylosin. The populations of the germinating spores were subjected to a short-term treatment with nitrosomethylurea during different periods of the first DNA replication cycle. The method reveals defines periods sensitive to mutation induction and isolates a mutant producing a 60% increase in the yield of tylosin as compared to that provided by the stock strain. 相似文献
Eleven samples of Pacific herring from the four seas of Eurasia (Sea of Japan, Sea of Okhotsk, Bering Sea, and White Sea), and one sample of Atlantic herring were analyzed. Complete and partial sequences of the mtDNA control region with the sizes up to 1071 bp were used. To verify the haplogroups identified, additional sequencing of the cytochrome oxidase I gene was performed. It was demonstrated that Pacific herring from the seas of Eurasia belonged to one mitochondrial haplogroup. The gene flow between the localities from different parts of the Far Eastern sea basins was about 11% per locality, per generation, which led to constant leveling of herring intraspecific differentiation. The data presented gave no reasons for subdivision of the herring populations in accordance to ecological characters (lacustrine and marine). Analysis of global molecular variance (global AMOVA) demonstrated that in Asian water basins, more than 98% of molecular polymorphism was found within the samples at the low level of significance (P < 0.05). 相似文献
Molecular weights of extracellular chitinases from wild-type B-10 (62, 54, 43, 38, and 21 kDa) and mutant M-1 strains of Serratia marcescens (62, 52, 43, 38, and 21 kDa) were estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the absence of chitin inductors, chitinolytic enzymes were not found in the culture liquid of B-10, while M-10 cells produced the chitinase complex (to 470 pU/cell). Crystalline chitin insignificantly stimulated the synthesis of chitinases with molecular weights of 62, 54, and 21 kDa by B-10 (up to 20 pU/cell), but caused overproduction of all chitinases by the mutant strain (up to 2600 pU/cell). Colloidal chitin induced the production of chitinases by cells of both strains. Two peaks of chitinolytic activity were observed during cultivation of strains B-10 (350 and 450 pU/cell) and M-1 (2200 and 2400 pU/cell). The first peak of cell productivity was associated with biosynthesis of the chitinase complex. The second peak was related to the production of enzymes with molecular weights of 54, 43, 38, and 21 kDa (B-10) or 43, 38, and 21 kDa (M-1). 相似文献
Hairy root cultures are often used to produce valuable metabolites. They are grown on sucrose-rich medium, which is highly susceptible to contamination. Trapa natans is a unique plant with photosynthesizing roots. It is a promising object to obtain photoautotrophic hairy root culture. Protocols for transformation of this species are yet unknown. We report that hairy roots can be induced in aquarium and in vitro cultures of T. natans by agrobacterium-mediated and biolistic transformation. 64 roots were induced by Agrobacterium rhizogenes strain 15834, two roots were obtained using strain K599. Strain A4 was not effective. Biolistics with either amplicons of rol genes and 1301 pCAMBIA plasmid carrying rol genes resulted in the formation of six roots. All these roots contained chloroplasts. This achievement opens a prospect for genetic transformation of T. natans and use of its green photosynthesizing hairy root cultures in production of bioactive substances and in phytoremediation.
Molecular weights of extracellular chitinases from wild-type B-10 (62, 54, 43, 38, and 21 kDa) and mutant M-1 strains of Serratia marcescens (62, 52, 43, 38, and 21 kDa) were estimated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. In the absence of chitin inductors, chitinolytic enzymes were not found in the culture liquid of B-10, whereas M-1 cells produced the chitinase complex (to 470 pU/cell). Crystalline chitin insignificantly stimulated the synthesis of chitinases with molecular weights of 62, 54, and 21 kDa by B-10 (up to 20 pU/cell), but caused oversynthesis of all chitinases by the mutant strain (up to 2600 pU/cell). Colloidal chitin induced the production of chitinases by cells of both strains. Two peaks of chitinolytic activity were observed during cultivation of strains B-10 (350 and 450 pU/cell) and M-1 (2200 and 2400 pU/cell). The first peak of cell productivity was associated with biosynthesis of the chitinase complex. The second peak was related to the synthesis of enzymes with molecular weights of 54, 43, 38, and 21 kDa (B-10) or 43, 38, and 21 kDa (M-1). 相似文献