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21.
Ken B. Waites Joseph G. Tully David L. Rose Peggy A. Marriott Richard O. Davis Dr. Gail H. Cassell 《Current microbiology》1987,15(6):325-327
Acholeplasmas have been isolated from a variety of animals, insects, and plants, but onlyAcholeplasma laidlawii has previously been found in humans. We have isolatedAcholeplasma oculi in pure culture from the amniotic fluid of a woman at 19 weeks of gestation. The organism was positively identified by growth inhibition, epi-immunofluorescence, and arbutin hydrolysis. Demonstration of organisms directly in amniotic fluid by DNA fluorochrome and immunofluorescence staining provided additional evidence that the isolate was genuine and not a medium contaminant. The remainder of the pregnancy was unremarkable, and a full-term male infant was delivered without complications. Even though there is some evidence possibly associatingA. oculi with various diseases in livestock, the prevalence and significance ofA. oculi in humans has not been determined. 相似文献
22.
A Saccharomyces cerevisiae genomic plasmid bank based on a centromere-containing shuttle vector 总被引:314,自引:0,他引:314
A set of genomic plasmid banks was constructed using the centromere-containing yeast shuttle vector YCp50. The centromere-containing vector is useful for the isolation of genes that are toxic to yeast when present in high copy number. Fourteen independent banks were prepared each with an average representation of two to three times the yeast genome. Any individual plasmid from a given bank is guaranteed to be of independent origin from plasmids obtained from each of the other banks. The banks were constructed from three different size classes of DNA fragments that resulted from varying conditions of partial digestion with Sau3A. This avoided the bias caused by differential sensitivity of sites to cleavage with Sau3A. Insert DNA is sufficiently large that most genes will be present in the set of plasmid banks at a frequency of about 0.1%. 相似文献
23.
Rose C. Wade Janet V. Powers Cyril Ponnamperuma 《Origins of life and evolution of the biosphere》1989,19(2):199-220
This bibliography is the seventeenth annual supplement to the comprehensive bibliography on the same subject which was published in Space Life Sci. 2(1970), 225-295; 3(1972), 293-304; 4(1973), 309-329 and in Origins of Life 5(1974), 505-527; 6(1975), 285-300; 7(1976), 75-85; 8(1977), 59-66; 9(1978), 67-74; 10(1980), 69-87; 10(1980), 379-404; 11(1981), 273-288; 12(1982), 93-118; 13(1983), 61-80; 15(1984), 55-69; 17(1987), 171-184; 17(1987), 185-206. 相似文献
24.
Temporal changes in the egglaying behaviour of the Hessian fly 总被引:1,自引:0,他引:1
Responses of mated female Hessian flies were investigated by analysing the behaviour of individual flies in wheat and oats. The behavioural repertoire of such females included: flying, alighting on leaves, arching of the body so that the tip of the abdomen touched the leaf surface, antennation, movements of the tip of the abdomen across the leaf at right angles to leaf veins, sitting with the ovipositor straight but still extended, and sitting with the ovipositor telescoped into the body. After alighting, females on wheat showed a higher frequency of transitions from arching to antennation and a lower frequency of transitions from arching to abdomen straight than females on oats. During the first 5 min of observations, individuals released into arenas with wheat arched and antennated 2–3 times more frequently than females released into oats. Time allotted to behaviours also differed; during the first 5 min, females in wheat spent 50 percent more time arching, whereas females in oats spent 50 percent more time sitting. Females in wheat also stayed longer and laid 4 times more eggs than females in oats. Temporal changes in egglaying were monitored by quantifying hourly rates of egglaying in no-choice assays for several hours following mating at 9:00 am. During the first and second hours post-mating, egglaying occurred infrequently. However, during the third hour post-mating (11:00 am to noon) females on wheat laid 5 times more eggs than females on oats. Rates of egglaying decreased on wheat but increased on oats during the fourth hour, and then during the fifth hour, decreased on both wheat and oats. Changes in egglaying responses were also evident when behaviours of individual females were measured 1–3 h vs. 3–7 h post-mating. Females deprived of host plants and released into wheat or oats later in the day showed higher frequencies of arching and antennation and laid more eggs before leaving the arena.
Résumé Les réactions de femelles préalablement accouplées de Mouches de Hesse ont été examinées en analysant le comportement de femelles isolées sur blé et sur avoine. Le répertoire comportemental de ces femelles comprenait: le vol, l'atterrissage sur feuille, la flexion du corps de sorte que l'extrémité de l'abdomen touchât la surface de la feuille, l'antennation, les mouvements de l'extrémité de l'abdomen sur la feuille à angle droit des nervures, le repos avec la tarière droite et encore dévaginée, le repos avec la tarière télescopée à l'intérieur du corps. Sur blé plus que sur avoine, les femelles après atterrissage ont présenté une fréquence plus élevée de passage de la flexion à l'antennation que de la flexion à l'abdomen droit. Durant les 5 premières minutes d'observation, les individus libérés dans des enceintes avec blé fléchirent et antennèrent 2 à 3 fois plus que ceux libérés sur avoine. Les durées des différentes séquences différaient aussi: sur blé, pendant les 5 premières minutes, les femelles passèrent plus de 50% du temps à fléchir, tandis que sur avoine elles passèrent plus de 50% du temps en repos. Les femelles restèrent aussi plus longtemps sur les feuilles de blé et y pondirent 4 fois plus d'oeufs que sur avoine.Les femelles de M. destructor ont montré une plasticité du seuil d'acceptation. Pendant les premières heures de ponte, elles ont été très sélectives et refusèrent, ou ne pondirent que quelques oeufs sur avoine, mais acceptèrent volontiers le blé. La discrimination s'est poursuivie tant que les femelles ont eu accès au blé en même temps qu'à l'avoine. Cependant, quand les femelles ont été privées de blé pendant plusieures heures, l'acceptation de l'avoine a augmenté. Cet accroissement de l'acceptation a eu lieu à peu près au moment où les femelles sur blé pondaient leurs derniers oeufs.相似文献
25.
Purification and characterization of a methionine-specific aminopeptidase from Salmonella typhimurium 总被引:1,自引:0,他引:1
P Wingfield P Graber G Turcatti N R Movva M Pelletier S Craig K Rose C G Miller 《European journal of biochemistry》1989,180(1):23-32
An aminopeptidase specific for methionine (peptidase M) has been purified from wild-type and mutant Salmonella typhimurium strains. Recombinant peptidase M was also purified from Escherichia coli. These preparations were characterized with respect to their physicochemical properties using analytical ultracentrifugation, SDS/PAGE, isoelectric focusing, titration curve analysis, amino acid analysis, N-and C-terminal sequencing and various spectroscopic methods. Peptidase M activity is stimulated by Co2+, in agreement with previous studies using crude extracts of Salmonella. The purified preparations did not contain significant amounts of any metal. Enzymically important metal is loosely associated and lost during enzyme purification. Peptidase M was shown to contain seven free sulphydryl residues none of which are involved in either intra-or inter-molecular disulphide bonds. Most appear solvent-accessible as evidenced by their reactivity under native conditions. Limited modification of the sulphydryl residues with either iodoacetamide or 5,5'-dithiobis(2-nitrobenzoic acid) led to inactivation. Several cysteines were shown to be labelled to various degrees by peptide mapping of inactivated S-[14C]carboxymethylated protein. Whether cysteine modification affects enzymic activity directly (blocking an active site) or indirectly (by causing conformational change) remains to be established. 相似文献
26.
Treatment of the host (Mus musculus, Gallus domesticus) with cyclosporin A during infection with Eimeria vermiformis or E. mitis resulted in a reduction in the numbers of oocysts passed in the feces and/or a delay in patency. The general immunosuppressive effects of the treatment were confirmed in chickens by monitoring their antibody responses to human erythrocytes and lymphoproliferative responses to phytohemagglutinin. Nevertheless, mice and chickens treated with cyclosporin A during a primary infection with E. vermiformis or E. mitis, respectively, were immune to subsequent challenge with these organisms. Thus, cyclosporin A did not interfere with priming. The antiparasite effect of the drug did not allow an evaluation of its effect on established immunity to the coccidia when it was administered at the time of challenge. In an exceptional treated chicken, however, delayed patency of the challenge infection was followed by the production of a number of oocysts similar to that found in unprimed animals. This suggests that the mechanisms of immunity to challenge may be susceptible to disruption by cyclosporin A. 相似文献
27.
At inflammatory sites neutrophils are stimulated to produce a variety of toxic agents, yet rarely harm the endothelium across which they migrate. We have recently found that endothelium releases adenosine which, acting via receptors on the surface of human neutrophils, inhibits generation of toxic metabolites by stimulated neutrophils but, paradoxically, promotes chemotaxis. Agents which diminish plasma membrane viscosity affect neutrophil function similarly, possibly by modulating chemoattractant receptor number or affinity. We therefore determined whether adenosine receptor agonists modulate neutrophil function by decreasing membrane viscosity and/or chaning the affinity of chemoattractant (N-fMet-Leu-Phe, FMLP) receptors. Surprisingly, 5′-(N-ethylcar☐amido)adenosine (NECA, 10 μM), the most potent agonist at neutrophil adenosine receptors, increased plasma membrane viscosity, as measured by fluorescence anisotropy of the plasma membrane specific probe 1-(4-trimethylaminophenyl)-6-diphenyl-1,3,5-hexatriene (TMA-DPH), in unstimulated neutrophils from a mean microviscosity of 1.67 ± 0.02 (S.E.) to 1.80 ± 0.02 (p < 0.001) while inosine (10 μM), a poor adenosine receptor agonist, had no effect (1.73 ± 0.04, p =n.s. vs. control, p < 0.01 vs. NECA). Adenosine receptor agonists increased plasma membrane viscosity in neutrophils with the same order of potency previously seen for inhibition of superoxide anion generation and enhancement of chemotaxis (NECA > adenosine = N6-phenylisopropyladenosine). The adenosine receptor antagonist 8-(p-sulfophenyl)theophylline reversed the effect of NECA on plasma membrane viscosity. Unlike other agents which modulate plasma membrane viscosity, NECA (10 μM) did not significantly change the number or affinity of [3H]FMLP binding sites on neutrophils. In contrast to the hypothesis of Yuli et al. these results indicate that occupancy of adenosine receptors on neutrophils increases plasma membrane viscosity without affecting chemoattractant receptor display. 相似文献
28.
C-terminal peptide identification by fast atom bombardment mass spectrometry. 总被引:1,自引:0,他引:1
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A previously described technique [Rose, Simona, Offord, Prior, Otto & Thatcher (1983) Biochem. J. 215, 273-277] permits the identification of the C-terminal peptide of a protein as the only peptide that does not incorporate any 18O upon partial enzymic hydrolysis in 18O-labelled water. Formation of chemical derivatives followed by combined g.l.c.-m.s. was used in this earlier work. We now describe the isolation from protein digests, by reversed-phase h.p.l.c., of labelled and unlabelled polypeptides and their direct analysis by fast atom bombardment mass spectrometry. Under the conditions used, the 18O label is retained throughout the separation and analysis, thus permitting assignments of C-terminal peptides to be made. Enzyme-catalysed exchange of label into the terminal carboxy group was found to occur in some cases without hydrolysis of a peptide bond. This effect, which may be exploited to prepare labelled peptides, does not prevent application of the method (two separate digests must then be used). We have applied our method to the analysis of enzymic partial hydrolysates of glucagon, insulin and of several proteins produced by expression of recombinant DNA. 相似文献
29.
The hydrated volumes, Vh, of collagens extracted from various fish species were calculated by using the Simha-Einstein equation, and it was found that the hydration of warm-water fish collagen is greater than that of cold-water fish collagen (halibut). Although the intrinsic viscosities of warm-water fish (bigeye-tuna, carp and catfish) collagens are almost the same, the hydrated volume of bigeye-tuna collagen is approx. 1.5 and 3 times those of carp and catfish collagens respectively. The extent of hydration at 20 degrees C is in the following order: bigeye tuna greater than carp greater than catfish greater than halibut. The various thermodynamic activation parameters (delta G*, delta H* and delta S*) were calculated and it was found that they are useful for determining the exact denaturation temperature. It was calculated that the denaturation temperatures of halibut, bigeye-tuna, carp and catfish collagens are 17, 31, 32 and 26-30 degrees C respectively. The variations of hydration, intrinsic viscosity, denaturation temperature and the thermodynamic parameters with the variation of concentration of catfish collagen were also thoroughly examined. The change of thermodynamic parameters from coiled-coil to random-coil conformation upon denaturation of collagen were calculated from the amount of proline and hydroxyproline residues and compared with viscometric results. 相似文献
30.
Insulin proteinase liberates from glucagon a fragment known to have enhanced activity against Ca2+ + Mg2+-dependent ATPase.
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K Rose L A Savoy A V Muir J G Davies R E Offord G Turcatti 《The Biochemical journal》1988,256(3):847-851
We find, contrary to previous reports, that substantial cleavage of glucagon by insulin proteinase occurs at only one region, namely the double-basic sequence -Arg17-Arg18-. Cleavage takes place almost exclusively between these two residues, liberating fragments glucagon-(1-17) and glucagon-(18-29). Others have shown that the fragment glucagon-(19-29) is 1000-fold more efficient compared with intact glucagon, at inhibiting the Ca2+-activated and Mg2+-dependent ATPase activity and the Ca2+ pump of liver plasma membranes. We show that this fragment is not liberated in detectable quantities by our insulin proteinase preparation. On the other hand, others have shown that glucagon-(18-29), though less active than glucagon-(19-29), was still 100-fold more active than glucagon itself in the above-mentioned system. Our observations represent the first demonstration of the release by insulin proteinase of a hormone fragment having enhanced activity, although it has yet to be shown that the activity of this fragment is important in vivo. Since the formation of glucagon-(19-29) from glucagon-(18-29) would involve merely removal of Arg18, a second enzyme might exist to provide the more active fragment. 相似文献