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排序方式: 共有965条查询结果,搜索用时 15 毫秒
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Evaluation of selectable markers for obtaining stable transformants in the gramineae 总被引:13,自引:5,他引:8 下载免费PDF全文
Hauptmann RM Vasil V Ozias-Akins P Tabaeizadeh Z Rogers SG Fraley RT Horsch RB Vasil IK 《Plant physiology》1988,86(2):602-606
Cell suspension cultures of Triticum monococcum, Panicum maximum, Saccharum officinarum, Pennisetum americanum, and a double cross trispecific hybrid between Pennisetum americanum, P. purpureum, and P. squamulatum were tested for resistance to kanamycin, hygromycin, and methotrexate for use in transformation studies. All cultures showed high natural levels of resistance to kanamycin, in excess of 800 milligrams per liter, and variable levels of resistance to hygromycin. Methotrexate was a potent growth inhibitor at low concentrations with all species. Kanamycin and hygromycin were growth inhibitory only if added early (within 5 days after protoplast isolation and culture). Protoplasts of T. monococcum, P. maximum, S. officinarum, and the tri-specific hybrid were electroporated with plasmid DNA containing hygromycin (pMON410), kanamycin (pMON273), or methotrexate (pMON806) resistance genes. Resistant colonies were obtained at low frequencies (1 × 10−5 to 2 × 10−6) when selected under conditions which were growth inhibitory to protoplasts electroporated without DNA. Southern blot hybridization confirmed stable integration of plasmid DNA into T. monococcum using hygromycin vectors and P. maximum using the methotrexate vector with 1 to 10 copies integrated per haploid genome. 相似文献
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Vasil Pirgozliev Stephen C. Mansbridge Izzy M. Whiting Stephen P. Rose Kristina Kljak Amy E. Johnson Falko Drijfhout Sylwia Orczewska-Dudek Atanas G. Atanasov Teodora Mihova 《The Annals of applied biology》2023,183(1):7-14
The aim of this study was to assess the effects of graded levels (0, 3, 6, 9 and 12 g/kg) of dry Sea buckthorn (SB) berries on growth performance, gastrointestinal tract (GIT) development, jejunal histomorphology, bird antioxidant status and caecal short-chain fatty acid concentration when fed to female Ross 308 broiler chickens. In addition, expression of cytokine biomarker genes in the jejunum was evaluated. The five experimental diets were fed from 7 to 21 days age to 8 pens (two birds in each) following randomisation. Feeding SB did not influence bird growth performance (p > .05). There was a linear decrease in butyric, acetic and valeric acid concentrations in caecal digesta (p < .05) and a decrease (p < .05) in crypt depth. The expression of IFNG and CD40LG responded quadratically (p < .05), peaking at 6–9 g/kg dietary inclusion of SB, respectively. Other studied variables were not affected by dietary SB inclusion (p > .05). Feeding dry SB berries up to 12 g/kg of diet did not improve the zootechnical variables of healthy commercial-strain broilers in this study. 相似文献
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Hazel A. Barton Zaiga Johnson Charles D. Cox Adriana I. Vasil & Michael L. Vasil 《Molecular microbiology》1996,21(5):1001-1017
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Cloning of a Phosphate-Regulated Hemolysin Gene (Phospholipase C) from Pseudomonas aeruginosa 总被引:24,自引:11,他引:13 下载免费PDF全文
Michael L. Vasil Randy M. Berka Gregory L. Gray Hiroshi Nakai 《Journal of bacteriology》1982,152(1):431-440
Phospholipase C (heat-labile hemolysin) of Pseudomonas aeruginosa is a phosphate (Pi)-regulated extracellular protein which may be a significant virulence factor of this organism. The gene for this hemolytic enzyme was cloned on a 4.1-megadalton (Mdal) fragment from a BamHI digest of P. aeruginosa PAO1 genomic DNA and was inserted into the BamHI sites of the multicopy Escherichia coli(pBR322) and P. aeruginosa(pMW79) vectors. The E. coli and P. aeruginosa recombinant plasmids were designated pGV26 and pVB81, respectively. A restriction map of the 4.1-Mdal fragment from pGV26 was constructed, using double and single digestions with BamHI and EcoRI and several different restriction enzymes. Based on information from this map, a 2.4-Mdal BamHI/BglII fragment containing the gene for phospholipase C was subcloned to pBR322. The hybrid plasmids pGV26 and pVB81 direct the synthesis of enzymatically active phospholipase C, which is also hemolytic. The plasmid-directed synthesis of phospholipase C in E. coli or P. aeruginosa is not repressible by Pi as is the chromosomally directed synthesis in P. aeruginosa. Data are presented which suggest that the synthesis of phospholipase C from pGV26 and pVB81 is directed from the tetracycline resistance gene promoter. The level of enzyme activity produced by E. coli(pGV26) is slightly higher than the levels produced by P. aeruginosa(pMW79) under repressed conditions. In contrast, the levels produced by P. aeruginosa(pVB81) are at least 600-fold higher than the levels produced by P. aeruginosa(pMW79) under repressed conditions and approximately 20-fold higher than those produced by P. aeruginosa(pMW79) under derepressed conditions. The majority (85%) of the enzyme produced by E. coli(pGV26) remained cell associated, whereas >95% of the enzyme produced by P. aeruginosa(pVB81) was extracellular. Analysis of extracellular proteins from cultures of P. aeruginosa(pMW79) and P. aeruginosa(pVB81) by high-performance liquid chromotography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the phospholipase C gene was cloned intact, and it is likely that several additional genes were cloned on the 4.1-Mdal fragment of DNA. It was also found that some of these genes encode proteins which are the same molecular weight as some previously described Pi-repressible proteins of P. aeruginosa. The existence of a Pi regulon of P. aeruginosa is proposed. It is likely that one of these genes also regulates the level of pyocyanin production by P. aeruginosa and that one or more play a role in transport or binding of Pi. The availability of the hybrid plasmids described herein will be useful in further studies on the role of this hemolysin in the virulence of P. aeruginosa and in the study of the genetics and physiology of Pi-regulated proteins. 相似文献