共查询到20条相似文献,搜索用时 15 毫秒
1.
Antibody responses and host resistance to the tapeworm, Hymenolepis microstoma, were investigated using and strains of mice. AKR mice were significantly more resistant than controls to a secondary infection following exposure to a 3-, 21-, or 40-day primary infection. During a primary infection, intestinal anti-worm antibody responses measured by an enzyme-linked immunosorbent assay were elevated in the more resistant AKR strain, whereas serum antibody titers did not differ between the two strains. However, during a secondary infection, serum IgA titers were higher in AKR mice than C3H mice. Suppression of the serum IgA anti-worm response by oral administration of lipopolysaccharide also suppressed resistance to a secondary infection. Intraperitoneal immunization with worm antigen resulted in a minor degree of protection in AKR mice. This protection was associated with increased intestinal antibody titers compared to mice not demonstrating protection. These results suggest that the protective responses observed in AKR mice relative to C3H mice reflect differences in mucosal antibody responses to H. microstoma. 相似文献
2.
Toshio Joh Tsuguhiko Yoshida Makoto Yoshimoto Takahisa Miyamoto Shoji Hatano 《Physiologia plantarum》1993,89(2):285-290
The composition and positional distribution of fatty acids in the polar lipids from 4 strains of Chlorella differing in chilling susceptibility and frost hardiness were analyzed by enzymatic hydrolysis and gas-liquid chromatography. Analysis of the polar lipids from chilling-sensitive, chilling-resistant and chilling-sensitive revertant strains of Chlorella ellipsoidea IAM C-102 showed that the sum of palmitic and trans -3-hexadecenoic acid in phosphatidylglycerol (PG) is about 60% for the sensitive strains and 53% for the resistant strain. The sum of dipalmitoyl and 1-palmitoyl-2-( trans -3-hexadecenoyl) PG as estimated from the positional distribution of their fatty acids, is about 10% in the case of each of the three strains. The contents of unsaturated fatty acids in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were higher in the resistant than in the sensitive strain. This suggests that unsaturation of fatty acids in not only PG but also PC and PE is involved in chilling sensitivity of Chlorella . On the other hand, lipid changes during the development of frost hardiness of C. ellipsoidea IAM C-27, a frost hardy strain, were examined. The results showed that fatty acids in most lipid classes are unsaturated in the hardening process but their degree of unsaturation is not greatly different from that of the chilling-resistant strain, suggesting that not only unsaturation of fatty acids in lipids but also other factors are necessary for the development of frost hardiness. 相似文献
3.
4.
The phase transition temperature () of dipalmitoyl phosphatidic acid multilamellar liposomes is depressed 10°C by the inhalation anesthetic methoxyflurane at a concentration of 100 mmol/mol lipid. Application of 100 atm of helium pressure to pure phosphatidic acid liposomes increased only 1.5°C. However, application of 100 atm helium pressure to dipalmitoyl phosphatidic acid lipsomes containing 100 mmol methoxyflurane/mol lipid almost completely antagonized the effect of the anesthetic. A nonlinear pressure effect is observed. In a previous study, a concentration of 60 mmol methoxyflurane/mol dipalmitoyl phosphatidylcholine depressed only 1.5°C, exhibiting a linear pressure effect. The completely different behavior in the charged membrane is best explained by extrusion of the anesthetic from the lipid phase. 相似文献
5.
Transposon (Tn5)-mediated suppressive integration of ColE1 derivatives into the chromosome of Escherichia coli K12 (dnaA) 总被引:1,自引:0,他引:1
While integration of ColE1 had not been observed previously by ordinary suppressive integration, a (Ts) strain with Tn at various sites of the chromosome and ColE1 or its mini-derivative, pAO3, but not pSC101, inserted by the same transposon produced integratively suppressed strains depending on the RecA function. In contrast to Hfr strains made with a stringently controlled plasmid, they contained the plasmid not only in an integrated but in an autonomous state at an amount comparable to the strain containing the plasmid only autonomously. Introduction of a RecA-deficient mutation to the strain with an integrated ColE1 derivative through conjugation failed. This is likely to be due to lethality of such a strain without RecA-dependent excision of the integrated high copy number plasmid or to quantitative deficiency of DNA polymerase I in addition to the mutation. 相似文献
6.
R Bachvarova 《Developmental biology》1981,86(2):384-392
7.
Comparison of photochemical activities and variable fluorescence yield characteristics of whole cells and isolated chloroplast particles of low-fluorescent, photosystem II mutants of to those of the wild-type showed that several strains were affected primarily on the oxidizing side of photosystem II. In strains LF-1, LF-3, and LF-5 analysis of the manganese content of isolated chloroplast membranes showed a predominant shift in the Chl from the wild-type value (4.3) to values near 1.5; this difference was also associated with a near total loss of cytochrome b-559 (high potential). Examination of chloroplast membrane polypeptides by gel electrophoresis revealed a decrease only in the mobility of one band in all three mutants; the apparent molecular weight was shifted from 34 kilodalton in the wild-type to 36 kilodalton in the mutants. Evidence is presented suggesting that the 34 kilodalton polypeptide of the wild-type is probably associated with the manganese requiring portion of the water-splitting apparatus of photosystem II. 相似文献
8.
(1) The polymorphic phase behaviour of aqueous dispersions of various synthetic phosphatidylethanolamines, both singly and in mixtures, has been investigated by 31P-NMR. (2) PE remains in the lamellar phase up to 90°C. PE exhibits a lamellar to hexagonal (HII) transition between 60°C and 63°C. For PE, the lamellar to hexagonal (HII) transition occurs between 7 and 12°C, whereas for PE, the hexagonal (HII) phase is the preferred structure above ?15°C. (3) Mixtures of PE and PE exhibit near-ideal miscibility behaviour. For mixtures of PE and PE there is evidence of fluid-solid immiscibility at temperatures below the gel-liquid crystalline transition temperature of the PE component. Mixtures of PE and PE exhibit complex phase behaviour involving limited fluid-solid immiscibility at low temperatures and formation of a phase allowing isotropic motional averaging at higher temperatures. (4) 31P-NMR provides a graphic method for investigating the miscibility properties of mixed PE systems. 相似文献
9.
T. Sasaki M. Yamasaki B. Maruo Y. Yoneda K. Yamane A. Takatsuki G. Tamura 《Biochemical and biophysical research communications》1976,70(1):125-131
Several tunicamycin resistant mutants were obtained from NA64. One of them, B7 strain produced a 5-fold larger amount of α-amylase than NA64 did. Only the amount of α-amylase, among excreted proteins, was enhanced. Genetic analyses by transformation suggested that a single mutation in B7 induced both resistance to tunicamycin and hyperproductivity of extracellular α-amylase. 相似文献
10.
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
11.
Elicitation of cell cultures of Silybum marianum with methyl jasmonate (MeJA) increases the production and release of the secondary metabolite silymarin into the culture
medium and this process seems to be dependent on phospholipase D activity and its product phosphatidic acid (PA). However,
MeJA did not alter total membrane lipid content or overall fatty acid composition. A progressive increase in some galactolipids
was observed with elicitation time. Phospholipids were mainly represented by phosphatidylcholine (PC) followed by phosphatidylethanolamine
(PE) and phosphatidylinositol (PI). MeJA caused losses of PC species that contain two unsaturated acyl species, 36:5 and 36:6
and an increase in 36:2 species. A drop in the ratio of compounds with 18:3 in PI and PE was also observed. The presence of
the lysophospholipids (LP) LPC (16:0, 18:3, 18:2, 18:1) and LPE (16:0, 18:3, 18:2, 18:1) and the high contents of PA, represented
by the molecular species 34:3, 34:2 and 36:5 and 36:4, indicates high basal level of phospholipase activity in cultures and
a high phospholipid turnover. MeJA treatment did not quantitatively alter these lipid classes. 相似文献
12.
R H de Jong 《Life sciences》1977,20(6):915-919
The bimolecular phospholipid membrane that separates axoplasm from extracellular fluid holds the key to nerve excitability: and so to local anesthesia. Local anesthetics block impulse propagation by preventing membrane depolarization. They do this by occluding the sodium pores (probably by plugging the channel's internal axoplasmic mouth). The positively charged local anesthetic binds to oppositely charged anionic channel components, whereas the uncharged lipid soluble anesthetic furnishes the carrier species that penetrates the membrane.Dissolved in water, local anesthetic salt crystals dissociate to yield anesthetic cation and base whose proportions are governed by the drug's fixed pKa and the tissue's variable pH. The more acid the surroundings, the more cation and the less base coexist. The cation/base concentration ratio is critical to optimal blockade. Too little base, and few anesthetic molecules manage to reach the neural target; too little cation, and few sodium channels will be plugged. 相似文献
13.
Elena C. McCoy G.David McCoy Herbert S. Rosenkranz 《Biochemical and biophysical research communications》1982,108(3):1362-1367
Characterization of a mutant strain (TA98/1,8-DNP6) resistant to the mutagenicity of nitrated polycyclic aromatic hydrocarbons (nitroarenes) revealed that it was also non-responsive to the mutagenic action of nitroso- and N-hydroxylaminoarenes. The mutant strain was fully sensitive to the mutagenic action of the corresponding hydroxamic acid ester. These results suggest that TA98/1,8-DNP6 is deficient in a specific esterifying enzyme and that esterification of the penultimate mutagenic metabolites of nitro- and aminoarenes (, arylhydroxylamines) to form potent electrophiles is controlled by a specific gene. 相似文献
14.
The courses of infection in inbred mouse strains were compared following infection with three Stabilates of high, intermediate, and low virulence of Trypanosoma vivax stock Zaria Y486. Mouse strains could only be shown to differ in their resistance to T. vivax infections as judged by the height of the initial parasitemia and survival times when a trypanosome population of low or intermediate virulence was used. A T. vivax population of high virulence was uniformly lethal. Comparison of lytic antibody titers between groups of resistant () and susceptible () mice did not show any significant differences in titers of the surviving mice but the mice in either group which did not control the initial parasitemia had lower lytic antibody titers than those which did. A significantly larger number of mice failed to control the initial infection as compared to the . Treatment with cyclophosphamide did not ablate differences in susceptibility between the two strains. The use of congenic mice showed that these differences in susceptibility were not related to differences in the major histocompatibility complex between these strains. 相似文献
15.
16.
E Gallori M Bazzicalupo B Parisi G Pedaggi M Polsinelli 《Biochemical and biophysical research communications》1978,85(4):1518-1525
A spontaneous mutant of resistant to (L)-azetidin-2-carboxylic acid, a structural analogue of (L)-proline, has been isolated and characterized. Data have been obtained which indicate that binding of [14C]-proline to tRNAs from the resistant strain is reduced only in part by (L)-azetidin-2-carboxylic acid, while a complete inhibition of binding occurs using tRNAs from parental strain. The mutation conferring resistance to the analogue and a mutation for proline auxotrophy have been mapped. 相似文献
17.
To assess the genetic component of the maternal age effect, the frequencies of aneuploid embryos derived from several inbred mouse strains were examined as a function of maternal age. Some of the strains were chosen to evaluate possible etiologic agents: CBA for premature reproductive aging and increased univalent frequency, and and for predisposition toward autoimmunity. The and strains also were examined. Although there was considerable variation between strains, an increased frequency of aneuploid fetuses was observed in all strains as a function of maternal aging. The CBA strain revealed the greatest increase in frequency of aneuploid fetuses at a relatively early maternal age. The effect of autoimmunity was assessed by analyzing the frequency of aneuploid embryos derived from thymectomized females. No significant difference in aneuploidy was found between thymectomized and control nonthymectomized animals. 相似文献
18.
Franz Meußdoerffer 《Biochemical and biophysical research communications》1980,97(2):423-429
The occurrence of the proteinase A inhibitors 2 and 3 was investigated in wild type strains of and as well as in several strains of commercial baker's yeast. Haploid and diploid strains of contain only proteinase A inhibitor 3 whereas in only proteinase A inhibitor 2 is found. Strains of commercial baker's yeast contain either proteinase A inhibitor 3 or both inhibitors in a constant ratio of 1:3. Single cell cultures isolated from a strain of commercial baker's yeast also contain a mixture of the two inhibitors. Therefore, baker's yeast is not a mixture of two different cell types but the genome for both inhibitors is present in each single cell. In general, the results indicate that the occurrence of the two proteinase A inhibitors is determined genetically and, therefore, they may be called “isoinhibitors”. 相似文献
19.
20.
Biosynthesis of glycerol teichoic acid in Bacillus cereus: formation of linkage unit disaccharide on a lipid intermediate 总被引:5,自引:0,他引:5
N Murazumi Y Sasaki J Okada Y Araki E Ito 《Biochemical and biophysical research communications》1981,99(2):504-510
A tunicamycin-like antibiotic 24010 at a concentration of 1 μg/ml selectively inhibited the synthesis of glycerol teichoic acid of cell walls in AHU 1030. Incubation of membranes of this strain with -acetylglucosaminyl pyrophosphorylundecaprenol and UDP--acetylmannosamine led to formation of a glycolipid having a saccharide moiety identical with the cell wall teichoic acid linkage unit, -acetylmannosaminylβ(1→4)--acetylglucosamine. The membranes also catalyzed transfer of glycerol phosphate units from CDP-glycerol to this disaccharide-linked lipid. Thus the biosynthesis of the cell wall glycerol teichoic acid in this strain seems to involve the disaccharide-linked lipid as an intermediate. 相似文献