共查询到20条相似文献,搜索用时 15 毫秒
1.
Santo Landolfo Maria Giovanna Martinotti Pancrazio Martinetto Guido Forni Anna Maria Rabagliati 《Experimental parasitology》1981,52(3):312-318
The genetic control of resistance or susceptibility to Trichomonas vaginalis infection has been studied in mice of various strains infected by different routes. and female mice appear to be highly susceptible to intraperitoneal, subcutaneous, or intravaginal infection by T. vaginalis. By contrast, female mice on A background are resistant to T. vaginalis infection via any route. and C3H female mice display intermediate levels of resistance following intraperitoneal or subcutaneous inoculum, whereas they display high levels of resistance to intravaginal infection. On the other hand, susceptibility or resistance to T. vaginalis infection appears to be influenced by the host sex, since males inoculated subcutaneously display much higher levels of resistance than females of the same strain. Lastly, the age of the host seems to play an important role in determining the course of infection. Susceptibility to T. vaginalis decreases with age, being maximal at 3–4 weeks and minimal at 40–42 weeks. All together these results suggest that resistance or susceptibility to T. vaginalis infection is regulated by genes mapping outside the major histocompatibility complex (H-2 in the mouse), whose activity is modulated by the anatomic site first coming into contact with the protozoon, the sex, and the age of the recipient host. 相似文献
2.
A Sugino 《Biochemical and biophysical research communications》1979,91(4):1321-1329
Mitochondrial DNA from contains high “A+T”-rich region. Its DNA replication starts in the “A+T”-rich region and proceeds unidirectionally around the molecule. In order to determine precise location of the DNA replication origin and elucidate unique feature of its nucleotide sequence, the “A+T”-rich region of mitochondrial DNA from has been cloned in . The chimeric plasmid DNA containing the “A+T”-rich region stimulates DNA replication system from mitochondria about ten fold higher than the parental plasmid DNA, as does native mitochondrial DNA. 相似文献
3.
Ken F. Jarrell Andrew M. Kropinski 《Biochemical and biophysical research communications》1981,99(4):1185-1190
Lipopolysaccharides (LPS) isolated from various rough derivatives of strains were found to neutralize coliphage T7. Concentrations of 0.4 – 17 μg LPS/ml were sufficient for 50% inactivation of T7 within 1 hour. From the LPS analyses of the mutants, it is believed that T7 may be binding to the heptose region of LPS, suggesting a similarity in structure between the heptose regions of and LPS. 相似文献
4.
Phosphorylation of calf thymus H1 histone by calcium-activated,phospholipid-dependent protein kinase
Yasushi Iwasa Yoshimi Takai Ushio Kikkawa Yasutomi Nishizuka 《Biochemical and biophysical research communications》1980,96(1):180-187
Ca2+-activated, phospholipid-dependent protein kinase recently found in mammalian tissues (Takai, Y., Kishimoto, A., Iwasa, Y., Kawahara, Y., Mori, T., and Nishizuka, Y. (1979) , 3692–3695) is able to phosphorylate five fractions of calf thymus histone. H1 histone serves as a preferential substrate, and approximately two moles of phosphate are incorporated into every mole of this histone. Analysis on the N-bromosuccinimide-bisected fragments of this radioactive histone has revealed that the enzyme phosphorylates preferentially seryl and threonyl residues located in the carboxyl-terminal half of this histone molecule. 相似文献
5.
John W. Kendrick 《Theriogenology》1976,5(3):150-152
and : Herds infected with have histories of infertility, occasional abortions, and pyometra.: There are no specific gross lesions in the fetus. The fetuses are usually aborted in the first half of gestation and may or may not be accompanied by the placenta.: There are no specific microscopic lesions.: It is ordinarily not necessary to culture in order to demonstrate its presence in placental fluids and/or abomasal contents.: There are no suitable seroligic procedures for diagnosing Trichomoniasis.: Wet mounts of abomasal contents and/or placental fluids are examined microscopically for .: Demonstrate the presence of by microscopic examination of wet mounts of placental fluids and/or abomasal contents. 相似文献
6.
Paul K. Tomich G. Robert Greenberg 《Biochemical and biophysical research communications》1973,50(4):1032-1038
Infection by , a temperature-sensitive mutant of gene 42 of phage T4, the structural gene for dCMP hydroxymethylase, previously was shown not to form T4 DNA at nonpermissive temperatures. Yet the enzyme activity was found in extracts. Since inactivation of the enzyme was not reversible, we have examined acid-soluble extracts of cells infected at nonpermissive temperature by for 5-hydroxymethyldCMP in order to determine whether the enzyme functioned . A double mutant of and (5-hydroxymethyldCMP kinase) did not form the nucleotide at nonpermissive temperature, but the control, , formed large quantities. From these results and previous temperature-shift studies it is suggested that the enzyme is normally activated to function between 5 and 8 minutes after infection. 相似文献
7.
Mouse L cell interferon (IFN ) inhibited the differentiation of mouse 3T3-Li fibroblasts into adipocytes. IFN also inhibited hexose monophosphate shunt (HMP) activity in these cells. HMP activity is required for the reducing power necessary for the conversion of 3T3-Li fibroblasts to adipocytes. Both IFN blockage of differentiation and HMP activity were reversed by the reducing agent 2-mercaptoethanol, probably through interaction with membrane receptors and not through direct inactivation of IFN. Several non-antiviral effects of IFN on cellular function, including differentiation and immunoregulation, may be mediated at the biochemical level through blockage of HMP activity. 相似文献
8.
A new endoribonuclease activity, RNase F, was partially purified from cells. This activity can cleave a precursor RNA molecule (of Species 1), isolated from T4 infected cells, in a specific site. This activity is different from the other three know processing endoribonucleases of RNase III, RNase E and RNase P. 相似文献
9.
Y Kawai H Takahashi T Fujita S Koga 《Biochemical and biophysical research communications》1979,88(2):410-414
The process of bacteriophage T4 morphogenesis was studied using a heat leakage scanning calorimeter. Thermograms of defective mutant 49 (am NG727) in permissive and non-permissive cells of showed a difference in thermal properties between packaged and non-packaged DNA molecules. , non-packaged DNA carried out their thermal transition at 85°C, the same temperature as that of T4 DNA melting measured in the standard saline citrate buffer, while the packaged DNA gave a sharper peak at 87°C due to some interaction with the head shell structure. Empty head shells showed a sharp heat absorption peak at 89°C both and , indicating the high degree of cooperativity in their conformational changes. 相似文献
10.
D J Prince D J Cummings R L Seale 《Biochemical and biophysical research communications》1977,79(1):190-197
We have used micrococcal nuclease as a probe of the repeating structure of chromatin isolated from the macronuclei of logarithmically and stationary grown and . For both these lower eukaryotes, the monomer size is shown to vary depending on the stage in the growth cycle. exhibits a monomer size of 153±7 bp and 178±6 bp and 207±10 bp and 230±10 bp in logarithmic and stationary cells, respectively. Both exhibit a nucleosome size of 140 bp. We discuss the possible association of these changes with histone content and nuclear activity changes, and also a possible reason for the divergence from the size pattern of monomer repeats seen in lower eukaryotes by . 相似文献
11.
Two compounds were isolated from female (Lepidoptera: Noctuidae) extracts and identified as -9-tetradecenal and -ll-hexadecenal. Together they elicit intense male . response in laboratory tests and have attracted males in the field. Although -ll-hexadecenal is an . sex pheromone, no evidence was obtained for -9-tetradecenal in . . 相似文献
12.
A temperature sensitive kanamycin (Km) resistant R plasmid, Rtsl, was found to confer cupric ion (Cu2+) resistance on its hosts in . At conjugal transfer, two kinds of segregants were obtained from Rtsl, i.e. Cu2+ resistant, Km sensitive and Km resistant, Cu2+ sensitive plasmids. Protein T existed in cells harboring Rtsl or the CurKms-plasmid. The inhibitory effect on the host cell growth at 43°C was observed with Rtsl+ or the KmrCus-plasmid+ cells. A relationship between these Rtsl derivatives and Rtsl in which has been studied was discussed. 相似文献
13.
Marit Nilsen-Hamilton Richard T. Hamilton W.Ross Allen Sharon L. Massoglia 《Biochemical and biophysical research communications》1981,101(2):411-417
Peptide growth factors selectively increase the amount of mitogen-regulated protein (MRP) and major excreted protein (MEP) released by mouse 3T3 cells. 3T3 cells release mainly MEP and Swiss 3T3 cells release mainly MRP. Fibroblast growth factor, epidermal growth factor, nerve growth factor, serum, and concanavalin A increase the extracellular appearance of both MEP and MRP, but to different extents. Several agents that have been shown to, or would be expected to increase, intralysosomal pH also selectively increase the release of MEP and MRP from both and Swiss 3T3 cells. The effective agents are monensin, nigericin, ammonium chloride, methylamine, chloroquine, and high extracellular pH. 相似文献
14.
Exonuclease V ( DNase) is inactivated in between 4 and 7 min after infection by T7. This process requires protein sythesis. The inactivation does not occur when T7 is deficient for its RNA polymerase and thus does not express the genes involved in DNA replication and phage maturation. Some implications of this new function of T7 are discussed with respect to the processes of infection and DNA replication. 相似文献
15.
Jörg Eder Minoru Osanai Suresh Mane Heinz Rembold 《Biochimica et Biophysica Acta (BBA)/General Subjects》1977,496(2):401-411
The development of a sensitive viroimmunoassay for honey bee cytochrome and its usage for early detection of caste differentiation is described. Pure honey bee cytochrome was isolated from workers and used to produce antibodies in rabbits. Bacteriophage T4 was chemically modified by covalent attachment of honey bee cytochrome using tolylene-2,4-diisocyanate as a cross-linking agent. The immunospecific inactivation of this bacteriophage-cytochrome c conjugate by anti-cytochrome antibodies can be inhibited by free cytochrome . In quantitative determinations, 50% inhibition is reproducibly achieved at a concentration of 6 ng/ml (5 pmol/ml) and as little as 0.3 ng/ml (0.25 pmol/ml) could be detected by this system. Cytochrome concentrations were measured in individual animals and substantial differences between corresponding larval stages of worker and queen bees are reported. 相似文献
16.
1-Aminoglycosides represent a new class of specific and relatively potent inhibitors of glycosidases. These compounds are specific against those enzymes which act upon glycosides that correspond to glycone of the inhibitor. Thus α- and β-- are inhibited by -glucosidases but not by -galactosylamine and -mannosylamine. α- and -galactosidases are inhibited by -galactosylamine but not by the other two glycosylamines. -Mannosylamine inhibits mannosidase. 相似文献
17.
Both enzyme-mediated group translocation and facilitated diffusion have been proposed as mechanisms by which mammalian cells take up purine bases and nucleosides. We have investigated the mechanisms for hypoxanthine and inosine transport by using membrane vesicles from Chinese hamster ovary cells (CHO), Balb/c 3T3 and SV3T3 cells prepared by identical procedures. Uptake mechanisms were characterized by analyzing intravesicular contents, determining which substrates could exchange with the transport products, assaying for hypoxanthine phosphoribosyltransferase activity, and measuring the stimulation of uptake of hypoxanthine by phosphoribosyl pyrophosphate ().We found that the uptake of hypoxanthine in Balb 3T3 vesicles was stimulated 3–4-fold by . The intravesicular product was predominantly IMP. The hypoxanthine phosphoribosyltransferase activity copurified with the vesicle preparation. These results suggest the possible involvement of this enzyme in hypoxanthine uptake in 3T3 vesicles. In contrast to the 3T3 vesicles, CHO vesicles prepared under identical procedures did not retain hypoxanthine phosphoribosyltransferase activity and did not demonstrate -stimulated hypoxanthine uptake. The intravesicular product of hypoxanthine uptake in CHO vesicles was hypoxanthine. These results and data from our kinetic and exchange studies indicated that CHO vesicles transport hypoxanthine via facilitated diffusion. An analogous situation was observed for inosine uptake; CHO vesicles accumulated inosine via a facilitated diffusion mechanism, while in the same experiments SV3T3 vesicles exhibited a purine nucleoside phosphorylase-dependent translocation of the ribose moiety of inosine. 相似文献
18.
C.H. Reynolds 《Biochemical and biophysical research communications》1975,67(2):538-543
NAD-linked α-glycerophosphate dehydrogenase plays a key role in the α-glycerophosphate cycle of . The activity in cell lysates was ample for this role. The enzyme was activated by salts (e.g. MgCl2 or NaCl); it had a broad pH-optimum for the reduction of dihydroxyacetone phosphate centred at pH 7.4, with an apparent Km of 0.5 mM; and it was weakly bound to particulate components of cell lysates. The enzyme from was similar to that of . These trypanosomal enzymes resemble that of the trypanosomatid , but are rather different from the enzymes of mammals, birds and insects. 相似文献
19.
T4 bacteriophage mRNA for lysozyme was extracted from T4 phage infected cells, partially purified by column chromatography, and translated in a heterologous cell-free protein synthesizing system prepared from wheat germ. The translation product was confirmed by SDS polyacrylamide gel electrophoresis and enzymatic activity — bacteriolysis as tested with . The specific activity of the enzyme prepared was 660 U/mg. 相似文献
20.
T-cell function during acute Toxoplasma gondii infection was evaluated in murine models. Blastogenic response to the T-cell mitogen concanavalin A (Con A) was not depressed during infection with either the C37 or the C56 strain of T. gondii in either or mice that were inoculated either intravenously or intraperitoneally with varying doses of tachyzoites 7, 14, or 30 days earlier. In evaluation of lymphocytes from individual mice, utilization of a range of concentrations of Con A was found to be important for correct interpretation of results. There was variability in the magnitude of response of individual mice and in the concentration of mitogen that produced an optimal response among the inbred mice. The T-cell-dependent, primary antibody response to sheep red blood cells (SRBC) was not depressed in mice infected with the C37 strain of Toxoplasma 1 and 8 days prior to inoculation with SRBC. A lower blastogenic reponse to Con A of lymphocytes from mice compared with that of mice appeared to correlate with increased susceptibility of mice to low-challenge inocula of T. gondii. 相似文献