共查询到20条相似文献,搜索用时 15 毫秒
1.
Darwin D. Smith Scott J. Norton 《Biochemical and biophysical research communications》1980,94(4):1458-1462
Sinefungin and A9145C, antifungal antibiotic analogs of S-adeno-sylmethionine isolated from , have been found to be very effective inhibitors of cyclopropane fatty acid synthase from . Both compounds exhibit linear competitive inhibition with a Ki for Sinefungin of 220 nM and a Ki for A9145C of 11 nM. 相似文献
2.
R J Irving-Bell 《Life sciences》1974,14(6):1149-1151
Electron microscopic examination of the gonads of six species of the complex revealed rickettsia-like, intracellular symbionts in , , and .1 In the two endemic Australian members, , no rickettsia-like symbionts were found, but virus-like particles were seen in the cytoplasm of the ovaries and certain associated tissues. 相似文献
3.
A functionally active ubiquinone derivative has been synthesized for the identification of the ubiquinone binding protein in ubiquinol-cytochrome reductase. After photolysis, the 14C activity was found to be specifically associated to proteins with mobilities relative to cytochrome of 0.841 and 0.475 in the sodium dodecylsulfate polyacrylamide gel electrophoresis of the Weber and Osborn system. These two proteins have previously been identified as cytochromes. The 14C activity distribution pattern was observed to be identical in the presence or absence of phospholipids during the photolysis. Antimycin A also produces no change in the 14C activity distribution among the proteins of this enzyme complex. 相似文献
4.
Isolation of coccidioides immitis from bat guano and preliminary findings on laboratory infectivity of bats with Coccidioides immitis 总被引:1,自引:0,他引:1
has been isolated from the guano of bats obtained beneath bat roosting places deep within deserted mine tunnels. Certain species of bats have been demonstrated to be susceptible to experimental infection by . There is, however, a difference in the laboratory susceptibility between the species studied ( and ). requires 8 times more arthrospores (400 as compared to 50) than does to produce a defineable infection. Our cultures for in the tissue of produced colonies of the bacterium . Because these tissues were handled under sterile conditions the presence of this red pigment (prodigiosin) producing bacterium was thought not the result of contamination. Prodigiosin suggests a possible mechanism for the apparent greatly reduced susceptibility to . found in the laboratory population of . Skin and serological tests on bats were negative as were cultures of guano from experimentally infected bats and mice. It is speculated that infected dying bats that fall to the floor beneath their roosting sites may contaminate the guano. We of course realize that other animals (we have found and rarely in these tunnels) may have tracked the fungus into these deep tunnel sites. 相似文献
5.
Throughout the non-gravid period, bacteriological samples and endometrial biopsy specimens were taken repetitively from the uteri of 93 cows in 9 dairy herds. The genital organs of 7 of the 14 cows which developed chronic purulent endometritis or pyometra were examined at slaughter 8 to 9 months after parturition. was recovered at least once from 61 (65.6 ) of the cows. The highest rate of infection was found during the second week post-partum. Intrauterine infection with invariably induced endometritis. The severity of the endometrial reaction was determined by the duration of the infection but the lesions never progressed to the “gland site mass” lesions and extensive stromal sclerosis which have been described as the “significant lesions” in endometritis.The duration of the infection also determined the effect of on fertility. Transient infection during the puerperium did not affect fertility; transient infection at a later period reduced fertility to one service, rarely to a second or third service; persistent infection induced chronic purulent endometritis or pyometra accompanied initially by functional anoestrum and, after some months, by organic anoestrum. The factors which determined the duration of the intrauterine infection with were not identified. 相似文献
6.
R E Benveniste G L Wilson G J Todaro 《Biochemical and biophysical research communications》1978,81(4):1363-1369
The squirrel monkey (,), a New World primate, contains multiple copies of endogenous type D retroviral gene sequences in the cellular DNA of all its tissues. Gene sequences partially homologous to these type D virus genes are also found in the cellular DNA of normal tissues of the New World carnivore, the skunk (, and ,). We there-fore conclude that this class of viruses has, under natural conditions, been transmitted between the germ lines of these evolutionarily distant species. The example of interspecies transmission described here is the first that has been described among New World species and also the first that has been demonstrated for retroviruses other than type C viruses. 相似文献
7.
V V Lyakhovich I B Tsyrlov O A Gromova N B Rivkind 《Biochemical and biophysical research communications》1978,81(4):1329-1335
The self-assembly of 3,4-benzpyrene hydroxylase system from the 3-methylcholanthrene-induced liver microsomes of mice and ( hybrids has been characterized by much higher efficiency than that one from control microsomes of these mice. This phenomenon was not observed in microsomes of mice. These data suggest that the regulation of aggregation process during the molecular morphogenesis of endoplasmic membranes in mice is of a dominantly inherited character. 相似文献
8.
Levansucrase, an exocellular enzyme, has been isolated from a high producer mutant, the BS5C4 constitutive strain, of Bacillus subtilis. Three crystalline forms have been obtained, all three belonging to the orthorhombic space group P212121. The most suitable form for a three-dimensional structure investigation has cell dimensions, , , . There is one molecule in the asymmetric unit. 相似文献
9.
C.R. Worthington A.R. Worthington 《International journal of biological macromolecules》1981,3(3):159-164
Low-angle X-ray diffraction patterns have been recorded from frog sciatic nerves in Ringer's solution after heat treatment from 20 to 80°C. The X-ray patterns were obtained from the heat treated specimens after cooling to room temperature. The normal X-ray pattern of frog sciatic nerve in Ringer's solution with was maintained from 20 to 58°C. Above 58°C, a new high temperature pattern based on a repeat period of was recorded from the nerve in Ringer's solution. The physical state of nerve myelin after heat teratment at a temperature ?58°C has been identified as the anomalous swollen state. Anomalous swelling takes place in units of four membranes. 相似文献
10.
John T. Dombrosky John A. Thomas Michael G. Mawhinney John W. Lloyd 《Life sciences》1973,13(7):795-804
Varying doses of morphine sulfate (10, 20 or 40 mg/kg daily × 10) were observed to suppress metabolic activities in the mouse prostate gland. Prostate gland fructose, an index of androgenic activity, was significantly reduced by these dose regimes of morphine (P < 0.01). Injections of morphine sulfate (20 mg/kg daily × 10) led to an inhibitition in the synthesis of both fructose?14C and sorbitol?14C from glucose?14C by the prostate gland, part of which may have been due to decreased uptake of glucose by the gland. The assimilation of 2-deoxyglucose?14C by the prostate was also reduced by morphine treatment. The actions of morphine (2 × 10?3M) on the metabolism of radioactive glucose by the mouse prostate gland likewise revealed a significant reduction in the formation of sorbitol?14C, but no decrease in fructose?14C formation. These results indicate that both the and actions of morphine can inhibit fructose metabolism in the prostate gland. 相似文献
11.
S K Arora 《Life sciences》1979,24(16):1519-1526
The crystal and molecular structure of the antitumor antibiotic mitomycin C has been determined by X-ray diffraction. The space group is monoclinic P21 with cell dimensions , , , β=95.99°(1) and Z=4. The structure was solved by direct methods. There are two independent molecules per asymmetric unit. The structure was refined to an R value of 0.049 for 2151 observed reflections measured on diffractometer. The benzoquinone ring is slightly deviated from planarity. The N4 in the indole ring behaves like an amide nitrogen owing to its participation in the conjugated benzoquinoid system. The five membered ring through C1, C2, C3, N4 and C9a adopts an envelope conformation. The molecules are held together in crystal by the hydrogen bonds. All nitrogens except N4 are involved in the hydrogen bonding. Studies with models of drug and DNA indicate two different kinds of mechanism for crosslinking. 相似文献
12.
The temperature dependence of the binding of PhNapNH2 () to vesicles of egg phosphatidylcholine has been determined. The Arrhenius plot of the association constant exhibits a discontinuity at 20.9 °C, some 30 °C above the broad phase transition region of the phospholipid. In the temperature range above 20 °C, and ; in the temperature range below 20 °C, and These values are consistent with the view that there are well ordered lipid-lipid bonds below 20 °C which are significantly less important above this temperature. The order in the temperature range of 5 to 20 °C, though significantly greater than that above 20 °C, is still significantly less than that in the crystalline state. 相似文献
13.
The dielectric dispersion in the MHz range of the zwitterionic dipolar phosphocholine head groups has been measured from 0–70°C for various mixtures of (DPPC) and cholesterol. The abrupt change in the derived relaxation frequency observed for pure DPPC at the gel-to-liquid crystalline phase transition at 42°C reduces to a more gradual increase of frequency with temperature as the cholesterol content is increased. In general the presence of cholesterol increases the DPPC head group mobility due to its spacing effect. Below 42°C no sudden changes in are found at 20 or 33 mol% cholesterol, where phase boundaries have been suggested from other methods. Above 42°C, however, a decrease in at cholesterol contents up to 20–30 mol% is found. This is thought to be partly due to an additional restricting effect of the cholesterol on the number of hydrocarbon chain conformations and consequently on the area occupied by the DPPC molecules. 相似文献
14.
Biosynthesis and excretion of meta and para tyramine in the rat 总被引:5,自引:0,他引:5
and tyramine, after conversion to their bis dansyl derivatives, have been identified and quantitated by mass spectrometry in rat urine. The daily to excretion ratio of 1.69 ± 0.10 is quite constant which suggests an endogenous origin for these amines. Following intraperitoneal injection of [14C] labelled dopa and dopamine more than tyramine is excreted; after i.p. injection of tyrosine only small amounts of tyramine could be identified. This implies that some tyramine is synthesised by a route other than dehydroxylation or decarboxylation. 相似文献
15.
C.A. Ruder R.G. Sasser R.J. Williams J.K. Ely R.C. Bull J.E. Butler 《Theriogenology》1981,15(6):573-580
Clinical conditions, which were observed in primiparous Angus and Hereford heifers with postpartum uterine infections are reported. Forty-three of sixty-four cows (67%) had uterine infections. and were the most frequently isolated aerobe and anaerobe, respectively. Twelve of the sixty-four cows (18.8%) had infections that involved these species. Three of these twelve cows were infected only with , two were infected only with , and seven were infected with both organisms. All five of the cows which were infected with either or showed signs of estrus and four of the five cows conceived by 110 days postpartum. The single cow that did not conceive was infected with . Three of the seven cows which were infected with both organisms showed signs of estrus and none of the seven cows conceived by 110 days postpartum. In addition, when only or was isolated from the uterus, cows had either mild or no clinical signs of infection. In contrast, the seven cows which were infected with both organisms had severe clinical signs of infection that included excessive vulvar discharge, uterine abscesses and pelvic adhesions. These observations suggested that a pathogenic synergism between and might have caused the increased severity of postpartum uterine infections, and the subsequent detrimental effect on return to estrus and conception. 相似文献
16.
Positron lifetimes in human red cell ghost membranes have been measured as a function of temperature from 3°C to 25°C. A marked sudden change in the annihilation rate was found at 16–18°C during the heating cycle and at 18–20°C in the cooling cycle. Such sudden change of microenvironment in the membranes sensed by is attributed to the sudden change of water diffusion rate through the membranes which is a consequence of the sudden change in free volume, or fluidities in the lipid layers. 相似文献
17.
Werner Goebel 《Biochemical and biophysical research communications》1973,51(4):1000-1007
The dependence of the replication of several plasmids on the chromosome-determined initiation products, A and C, has been studied. The initiation of the replication of E1 DNA requires the chromosomal A product. In contrast two de-repressed transfer factors ( and 152) seem to determine a corresponding plasmid-specific factor. The C-product is necessary for the ordered initation of all plasmids studied. The addition of low concentrations of chloramphenicol leads to a relaxed replication of E1 DNA at the restrictive temperature in A-mutants, but not in C-mutants. 相似文献
18.
F.R. Serna I.I. Samoylenko 《Biochemical and biophysical research communications》1975,67(4):1415-1421
The existence of the super fast repairing system for single-strand breaks in DNA, induced in cells exposed to gamma-irradiation at 0°C in a phosphate buffer under aerobic conditions, has been shown in three strains of Escherichia coli K-12 (AB 1157 , AB 2463 and JC 4457 ). Super fast repairing system rejoins up to 90–95 % of initial single-strand breaks during irradiation. An estimation of the lower limit of the rate of repairing the breaks by this system has been made. 相似文献
19.
Mahendra K. Jain Michael A. Singer Roger W. Crecely Hassan Pajouhesh Anthony J. Hancock 《生物化学与生物物理学报:生物膜》1984,774(2):199-205
In a previous publication, (Singer, M.A., Jain, M.K., Sable, H.Z., Pownall, H.H., Mantulin, W.W., Lister, M.D. and Hancock, A.J. (1983) Biochim. Biophys. Acta, 731, 373–377), we reported the properties of aqueous dispersions of the six diastereo-isomers of cyclopentanoid analogues of dipalmitoylphosphatidylcholine. Two of these isomers displayed unusually high enthalpies of transition, about double that of dipalmitoylphosphatidylcholine. One of the high enthalpy isomers whose configuration is all-trans has now been modified by the insertion of extra methylene residues ( through 9) between the nitrogen and phosphorus atoms of the headgroup. Vesicles were formed from these lipids and studied by 22Na permeability measurements, differential scanning calorimetry, fluorescence polarization, 31P-NMR, and freeze-fracture electron microscopy. Vesicles composed of lipids with or 3 exhibit a sharp transition at 46°C or 49°C, respectively, and a high enthalpy with no detectable sub- or pretransitions. Lipids with exhibit a main transition between 38 and 43°C with enthalpies and after prolonged cooling (more than 3 days at 4°C) a broad endotherm at about with enthalpies . These same dispersions display a permeability peak at 20–25°C and a second increase in 22Na efflux in the temperature range 30–40°C. The results of 31P-NMR measurements suggest that the acyl chains in 2,3-dipalmitoylcyclopentanol-phosphocholine () bilayers have restricted rotation below the main phase transition temperature. 相似文献
20.
Electron microscopy of the dissociation products of α-hemocyanin of the snail Helix pomatia reveals two distinctly different conformations of -size molecules: a C(compact)-form at high ionic strength and pH near 8, and an L(loose)-form at low ionic strength and/or higher pH.The size and shape of the C--size molecules indicate a dissociation of the -size molecules along the (10,9) helical grooves, which have been shown to be boundaries between the morphological units of the cylinder wall (Mellema &; Klug, 1972). The 5-fold collar is distributed evenly among the C--size molecules.The C → L conformational change is characterized by a drastic loosening of the -size molecules to a flexible cluster of globules, with a concomitant decrease of sedimentation coefficient and increase of intrinsic viscosity and frictional ratio.The -size molecule appears as a flexible, linear chain of seven or eight globules with a diameter of 55 to 60 Å. These globules are inferred to be the minimal oxygen binding units with a molecular weight of about 50,000, linked together by short stretches of the polypeptide chain.Stable intermediate dissociation products, , and -size molecules, were obtained by intramolecular crosslinking of -size molecules with dimethyl-suberimidate prior to dissociation. 相似文献