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21.
A method for efficient isotopic labeling of recombinant proteins 总被引:15,自引:0,他引:15
A rapid and efficient approach for preparing isotopically labeled recombinant proteins is presented. The method is demonstrated for 13C labeling of the C-terminal domain of angiopoietin-2, 15N labeling of ubiquitin and for 2H/13C/15N labeling of the Escherichia coli outer-membrane lipoprotein Lpp-56. The production method generates cell mass using unlabeled rich media followed by exchange into a small volume of labeled media at high cell density. Following a short period for growth recovery and unlabeled metabolite clearance, the cells are induced. The expression yields obtained provide a fourfold to eightfold reduction in isotope costs using simple shake flask growths. 相似文献
22.
The committed step in menaquinone biosynthesis is the formation of o-succinylbenzoate (OSB). It is presumed to require the reaction of a seven-carbon intermediate of the shikimate pathway with a succinic semialdehyde-thiamin pyrophosphate (TPP) anion, derived by decarboxylation of 2-ketoglutarate. The following evidence indicates that the decarboxylation is not a function of the ketoglutarate dehydrogenase complex but is carried out by a separate activity. (A) Cell-free extracts of Escherichia coli K12 without added TPP lose OSB synthase activity but retain all of the ketoglutarate dehydrogenase complex activities. (B) OSB synthase activity is inhibited by addition of tetrahydro-TPP (th-TPP) to the incubations. The ketoglutarate dehydrogenase complex activities are only inhibited by this analogue after an initial preincubation period. (C) The high molecular weight ketoglutarate dehydrogenase complex can be separated from OSB synthase activity by gel-permeation chromatography on Sepharose CL-6B. Experiment series A and B also provide supporting evidence that TPP does play an important role in menaquinone biosynthesis. 相似文献
23.
The amount of prostaglandin-like substance (PG - LS) in the reproductive tract of the male and female rat following mating (p.c.) has been measured and compared with non-mated (control) values. Negligible amounts of PG-LS were detected in the control female tracts but a mean of 2 μg PGE1 equivalents was detected immediately p.c. The PG-LS is probably generated in the vas deferens since nearly 1 μg PGE1 equivalents per rat remained there p.c. No other tissue in the male reproductive tract contained significant amounts of PG-LS. Further extraction and chromatography of the PG-LS suggests that the bulk of the activity is due to PGE2 with a smaller amount being due to PGF2α. 相似文献
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Robyne Castles Fiona Woods Peter Hughes John Arnott Louise MacCallum Sarah Marley 《Ecology and evolution》2021,11(23):16524
Harbour seals (Phoca vitulina) and grey seals (Halichoerus grypus) both occur within the UK, but display regional contrasting population trends. While grey seals are typically increasing in number, harbour seals have shown varying trends in recent decades following repeated pandemics. There is a need for monitoring of regional and local populations to understand overall trends. This study utilized a 20‐year dataset of seal counts from two neighboring harbours in the Solent region of south England. Generalized additive models showed a significant increase in the numbers of harbour (mean 5.3–30.5) and grey (mean 0–12.0) seals utilizing Chichester Harbour. Conversely, in Langstone Harbour there has been a slight decrease in the number of harbour seals (mean 5.3–4.0). Accompanying photographic data from 2016 to 18 supports the increase in seal numbers within Chichester Harbour, with a total of 68 harbour and 8 grey seals identified. These data also show evidence of site fidelity of harbour seals in this area, with almost a quarter of animals resighted within the past three years. Overall, this long‐term study indicates an increasing number of both harbour and grey seals within the Solent. However, more research is required to identify the drivers of this trend. 相似文献
28.
Marley R Lu W Balment RJ McCrohan CR 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2008,151(1):71-77
Previous studies have shown roles for cortisol and prolactin in osmoregulatory adaptation to seawater and freshwater, respectively, in euryhaline fish. This study of the European flounder investigated the potential for these hormones to modulate activity of the caudal neurosecretory system (CNSS), which is thought to be involved in physiological adaptation to changing external salinity. Superfusion of isolated CNSS with either cortisol or prolactin (10 microM; 15 min) led to changes in firing activity in neuroendocrine Dahlgren cells, recorded extracellularly. Cortisol evoked a modest increase in overall firing activity, with the response delayed by 4 h after treatment. The response to prolactin was short latency, continued to build up over the subsequent 4-h wash period, and comprised increased firing activity together with recruitment of previously silent Dahlgren cells. Immunoreactivity for glucocorticoid and prolactin receptors was localised to Dahlgren cells. The CNSS expression level for glucocorticoid-2 receptor mRNA, measured by Q-PCR, was significantly lower in fish fully acclimated to freshwater, compared to seawater. No differences were seen between these two states for prolactin receptor mRNA expression. These results provide evidence for a modulatory action of both hormones on the neurosecretory function of the CNSS. 相似文献
29.
Givens MD Marley MS Riddell KP Galik PK Stringfellow DA 《Animal reproduction science》2009,113(1-4):283-286
Bovine viral diarrhea virus (BVDV) can associate with in vitro fertilized (IVF) bovine embryos despite washing and trypsin treatment. An antiviral compound, DB606 (2-(4-[2-imidazolinyl]phenyl)-5-(4-methoxyphenyl)furan), inhibits the replication of BVDV in bovine uterine tubal epithelial cells, Madin Darby bovine kidney cells, and fetal fibroblast cells. As well, DB606 in in vitro culture medium does not affect embryonic development. Antiviral-treated-IVF embryos placed into recipients developed into clinically normal calves. The objective of this project was to determine if these resultant heifer calves were capable of reproducing. Seven heifers from each of the treatment groups (natural breeding, IVF embryo, and IVF embryo cultured in DB606) of the previous study were used. At 20-27 months of age, the heifers were exposed to a fertile bull in a single pasture during a 63 d breeding season. Five of the seven heifers originating from natural breeding were pregnant 35 d after removal of the bull and calved. All of the heifers resulting from transfer of untreated IVF embryos were pregnant at 35 d; however, one aborted the fetus at 5-7 months of gestation. All of the heifers derived from transfer of IVF embryos cultured in DB606 were pregnant and calved. Offspring from dams of all treatment groups were clinically normal at birth. Adjusted 205 d weaning weights were not significantly different among the offspring of the treated and untreated dams. These results indicate that culture of bovine-IVF embryos in DB606 does not impair future reproductive capacity of resulting heifers. 相似文献
30.
Michael CW Chan Renee WY Chan Wendy CL Yu Carol CC Ho WH Chui CK Lo Kit M Yuen Yi Guan John M Nicholls JS Malik Peiris 《Respiratory research》2009,10(1):102