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81.
82.
Douglas M. Templeton Anna Paudyn Andrew D. Baines 《Biological trace element research》1989,22(1):17-33
Interest in the biological behavior of a growing number of elements, along with increasing recognition of the importance of interactions among them, demands a versatile and reliable technique for multielement analysis of biological samples. Significant improvements over the sensitivity achieved with conventional inductively coupled plasma (ICP) optical emission spectrometries have been realized with the introduction of quadrupole mass spectrometry (MS) for detection of ions in the plasma. The hybrid technique of ICP-MS promises to be a method of rapid multielement analysis, at detection limits that approach or surpass those of other technologies. However, the application of ICP-MS to analyses of biological interest is truly in its infancy. Here we report the use of ICP-MS for the determination of more than 30 elements of biological interest in a tissue and a biological fluid (rat liver and serum, respectively). Experimental values of the elements serve as a basis for discussion of analytical protocols, performance criteria, and certain problems peculiar to ICP-MS. 相似文献
83.
Charlene P. Wight Andrew J. Daugulis Reginald H. Lau Bradley N. White 《Applied microbiology and biotechnology》1989,31(4):338-341
Summary
Bacillus brevis 47 was cultivated in 2-1 fermentors to study the effect of medium supplementation on extracellular protein production. Additional polypeptone, when supplied initially or at 12 h (late exponential phase), had little stimulatory effect on extracellular protein levels, which reached 6–7 g/l after 48h. A large increase in protein production was observed, however, when polypeptone was added at 21 h (stationary phase). This addition resulted in the accumulation in the medium of 14 g/l protein after 48 h, and a total of 16 g/l when cell-bound protein was included. In all cases, glucose was consumed only very slowly. 相似文献
84.
Andrew Clarke J. Cynan Ellis-Evans Mark W. Sanders Lesley J. Holmes 《Hydrobiologia》1989,172(1):183-191
The copepod Pseudoboeckella poppei (Daday) (Calanoida, Centropagidae) was sampled from Sombre and Heywood Lakes on Signy Island, Antarctica (60° S, 45° W) between January 1984 and March 1985. Sombre Lake is clear and oligotrophic with little phytoplankton and a bottom sediment low in organic content. By contrast Heywood Lake is turbid and mesotrophic; a substantial phytoplankton develops in summer and the bottom sediments are comparatively rich in organics. Both lakes freeze over for much of the year, forcing the copepods to adopt a benthic feeding strategy over winter. Adult Pseudoboeckella feed on phytoplankton when this is available, but also on detritus, diatoms and short algal filaments stirred up from the sediment. In Heywood Lake, male copepods show a smooth seasonal trend in lipid content with lipid being synthesised in early summer and utilised in late summer and winter. The summer increase in lipid content is associated with an increase in dry weight. Female lipid contents show evidence of two peaks of egg production. In Sombre Lake both male and female copepods increase in size during summer and show a wider range of lipid contents than in Heywood Lake; it is likely that this is due to the poorer winter feeding conditions which necessitate the synthesis of a much larger store of reserves during the summer. In contrast to marine calanoid copepods, lipid stores are exclusively triacylglycerol with no trace of wax ester. 相似文献
85.
Vesna A. Eterović Lian Li Andrew Palma Mark G. McNamee 《Cellular and molecular neurobiology》1990,10(3):423-433
1. Nicotinic acetylcholine receptors (nAChR)4 from BC3H1 cells (which express a skeletal muscle-type receptor) and from Torpedo californica electric organ were expressed in Xenopus laevis oocytes and studied with a voltage-clamp technique. 2. We found that bath application of ATP in the micromolar to millimolar range increased the ACh-elicited current in both muscle and electrocyte receptors. The effect of ATP increased with successive applications. This "use-dependent" increase in potentiation was Ca2+ dependent, while the potentiation itself was not. 3. Four other nucleotides were tested on muscle nAChR: ADP, AMP, adenosine, and GTP. Of these, only ADP was a potentiator, but its effect was not use dependent. Neither ATP nor ADP affected the resting potential of the oocyte membrane. 4. ADP potentiated the response to suberyldicholine and nicotine, as well as ACh. 5. Finally, ADP reversed the phencyclidine-induced block of ACh currents in oocytes expressing muscle nAChR. 相似文献
86.
Rosalita M Smagula Herman Van Halbeek Jean M Decker Andrew V Muchmore Charles E Moody Anne P Sherblom 《Glycoconjugate journal》1990,7(6):609-624
The urinary glycoprotein uromodulin (Tamm-Horsfall glycoprotein) exhibits a pregnancy-associated ability to inhibit antigen-specific T cell proliferation, and the activity is associated with a carbohydrate moiety [Muchmore and Decker (1985) Science 229:479–81; Hessionet al., (1987) Science 237:1479–84; Muchmore, Shifrin and Decker (1987) J Immunol 138:2547–53]. We report here that the Man6(7)GlcNAc2-R glycopeptides derived from uromodulin inhibit antigen-specific T cell proliferation by 50% at 0.2–2 M, and further studies, reported elsewhere, confirm that oligomannose glycopeptides from other sources are also inhibitory, with Man9GlcNAc2-R the most inhibitory of those tested [Muchmoreet al., J Leukocyte Biol (in press)]. In this work, we have extended the observation of pregnancy-associated inhibitory activity to a second species, and have compared the oligomannose profile of Tamm-Horsfall glycoprotein (nonpregnant) with that of uromodulin (pregnant) derived from both human and bovine sources. Surprisingly, there was a pregnancy-associated decrease in the total content of oligomannose chains due predominantly to a reduction in Man5GlcNAc2-R and Man6GlcNAc2-R. Man7GlcNAc2-R, which did not decrease with pregnancy, comprised a significantly greater proportion of the total oligomannose chains in pregnant vs. nonpregnant samples from both species (human; 34.6% vs. 25.9%: bovine; 14.4% vs. 7.2%). 相似文献
87.
Andrew J. P. Francis Grahame J. Coleman 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1990,167(3):357-362
Summary We examined the effect of cycles of 12 h warm (35 ± 2 °C) and 12 h (21 ± 2 °C) ambient temperature (Ta) upon the circadian activity rhythms of stripe-faced dunnarts, Sminthopsis macroura, free-running in conditions of constant dark (DD) or constant light (LL). It was hypothesized that dunnarts would entrain to the temperature cycles (TaHLs) or show perturbations of period, and that LL would act synergistically with the TaHLs in these effects. Under DD, 2 of 6 animals showed clear entrainment to the TaHLs. Other animals exhibited changes of period () and heavy negative masking of activity during the warm fraction of the TaHLs. Under LL, 3 of 12 animals entrained to the TaHLs. It was concluded that Ta is a significant though weak Zeitgeber for S. macroura compared to light. It is possible that TaHLs entrain homeotherm activity rhythms by altering the rhythm of body temperature, which is usually tightly coupled to activity.Abbreviations
TaHL
a cycle of Higher and Lower ambient temperature
-
TaC
Constant Ta
-
Tb
body temperature 相似文献
88.
Plasmid content in Yersinia pestis strains of different origin 总被引:5,自引:0,他引:5
Andrew A. Filippov Nikolai S. Solodovnikov Liubov M. Kookleva Olga A. Protsenko 《FEMS microbiology letters》1990,67(1-2):45-48
Plasmid content in 242 Yersinia pestis strains from various natural plague foci of the U.S.S.R. and other countries was studied. Of these strains, 172 (71%) were shown to carry three plasmids described previously of about 6, 45-50 and 60 MDa, respectively. Twenty strains (8%) from different foci harboured additional cryptic plasmids, most often of about 20 mDa in size. Plasmid pPst displayed considerable constancy of its molecular mass. On the contrary, size variations of pCad (45-49 MDa) and, especially, pFra (60-190 MDa) were found. Molecular mass of these plasmids correlated with the host strain origin. 相似文献
89.
To analyze the sexual behavior of male black-legged deer ticks Ixodes dammini,we collected ticks infesting 202 white-tailed deer. On average, 17.7 males and 8.8 females infested each deer. Field-collected males copulated with a mean of 2.25 females, and virgin males mated with 2.4 females. On experimental hosts, males established sexual contact with feeding females and repelled other males, and about half remained paired after their mate detached. Engorged females continue to be receptive, and males mate more readily with them than with nonfed females. We conclude that male I. damminiare endowed with a repertoire of behaviors which favor an opportunistic mating before seeking a host and a preference for mating with feeding females on the host accompanied by tenacious mate guarding. 相似文献
90.
Activity of branched-chain 2-oxo acid dehydrogenase complex in rat liver mitochondria and in rat liver.
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Four mitochondrial marker enzymes were used to show that: (1) high-protein (24%) diet increased the rat liver concentration and content of total branched-chain 2-oxo acid dehydrogenase complex (BCDC) by 31% by increasing mitochondrial specific activity of BCDC; (2) starvation increased the liver concentration of BCDC by 25% by decreasing liver weight; the liver content of mitochondria and the mitochondrial specific activity of BCDC were unchanged; (3) protein-free diet decreased rat liver BCDC concentration and content by 20%, by decreasing the liver concentration and content of mitochondria. Protein-free diet increased liver mitochondrial specific activities of L-glutamate, 2-oxoglutarate and NAD-isocitrate dehydrogenases. The validity of a mitochondrial method for the determination of the liver concentration of BCDC and the percentage in the active form in vivo is confirmed, and improvements are described. The experimental basis of criticisms of its use in this regard by Zhang, Paxton, Goodwin, Shimomura & Harris [(1987) Biochem. J. 246, 625-631] was not confirmed. The finding by Harris, Powell, Paxton, Gillim & Nagae [(1985) Arch. Biochem. Biophys. 243, 542-555], that starvation has no effect on the percentage of BCDC in the active form in rat liver, is confirmed. 相似文献