首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
Nucleotide pyrophosphotransferase (NPT) activity of two Streptomyces griseus strains was studied in submerged culture during their life cycle. NPT activity could be detected only in the culture filtrate but not in the membrane fraction or in cell extract of the sporulating (streptomycin-non-producing) S. griseus No. 45-H. No enzyme could be detected in the non-sporulating (streptomycin-producing) S. griseus No 52--1 cultures.  相似文献   

2.
Vertebrate animals collected in Haiti in 1972 were tested for selected zoonotic diseases. No rabies virus or neutralizing (N) antibody was detected in bats (Artibeus jamaicensis). However, N antibody against St. Louis encephalitis, Western equine encephalitis (WEE), and Eastern equine encephalitis were detected in resident species of birds and WEE antibody in bats. No N antibody against Venezuelan equine encephalitis was found. The possible introduction by migratory birds and local transmission of these arboviruses is discussed.  相似文献   

3.
We have investigated the daughter of a woman with Kearns-Sayre syndrome. The woman had a high percentage of deleted mtDNA in muscle, but no deleted mtDNA was detected in fibroblasts, bone marrow, and peripheral blood cells by Southern blot analysis. With PCR, analytical sensitivity was significantly increased, and deleted mtDNA was detected in all examined tissues from this patient. The patient had healthy parents and nine healthy siblings. No deleted mtDNA was detected in blood from the mother of the patient. The patient had an uneventful pregnancy and delivered at term. Deleted mtDNA could not be detected in placenta by Southern blot analysis. With PCR, deleted mtDNA was detected in the majority of placental specimens. This finding may, however, be due to contamination with maternal DNA. The patient's daughter was healthy at age 5 mo, and morphologic examination of muscle was normal. No transmission of deleted mtDNA to the daughter could be detected by Southern blot and PCR analysis of peripheral blood cells, bone marrow, fibroblasts, and muscle. The presence of deleted mtDNA was excluded at a fractional level of less than 1:100,000 in all examined tissues from the daughter.  相似文献   

4.
Tamm–Horsfall urinary glycoprotein. The chemical composition   总被引:7,自引:0,他引:7       下载免费PDF全文
1. A revised amino acid and carbohydrate composition of human Tamm-Horsfall glycoprotein is presented. 2. No significant differences were obtained in the amino acid composition of Tamm-Horsfall glycoprotein isolated from patients with cystic fibrosis. 3. The glycoprotein was shown to possess a high half-cystine content of 1 per 11-12 amino acid residues, which has been confirmed by performic acid oxidation and S-alkylation with iodoacetate and iodoacetamide. No thiol groups were detected in the glycoprotein. 4. Treatment of the glycoprotein with 0.5m-sodium hydroxide at 4 degrees C for 2 days did not release heterosaccharide material, which suggests that the predominant carbohydrate-protein linkages present are not of the O-glycosidic type. 5. No N-terminal amino acid was detected in the glycoprotein.  相似文献   

5.
Phylogenetic distribution of glutathione peroxidase.   总被引:7,自引:0,他引:7  
1. The enzyme glutathione peroxidase (E.C.1.11.1.9), known to be a selenoprotein from mammalian sources, was detected in the following vertebrates: fish, frog, salamander, and turtle. 2. Among invertebrates, the enzyme was detected in crayfish and snail but not in insects or earthworm. 3. No plant tissues or microorganisms showed any evidence of the enzyme activity. 4. The presence of the enzyme activity in so many animal groups implies the widespread occurrence of genetic information for the specific assimilation of the selenium atom.  相似文献   

6.
Type C virus-specific RNA sequences of BALB/c endogenous virus were detected in JLS-V9 cells (an uninfected BALB/c derived line) by annealing cell RNA with 3-H-labeled virus-specific DNA. Endogenous viruses used in preparing the 3-H-labeled DNA (mostly xenotropic) was prepared from JLS-V9 cells induced to produce virus with iododeoxyuridine. In whole-cell extracts, two virus-specific RNA species, 38S and 27S, were detected. No 60 to 70S virus-specific RNA was found. The same two species of virus-specific RNA were observed in isolated cytoplasmic RNA and in cytoplasmic RNA selected for polyadenylic acid-containing species by binding and elution from oligo(dT) cellulose. Very little, if any, of the virus-specific RNA was active as messenger RNA on polyribosomes. No virus-specific RNA transcribed from genes coding for the BALB/c endogenous N-tropic virus was detected, since 3-H-labeled DNA prepared from endogenous N-tropic virus did not hybridize measurably with JLS-V9 RNA.  相似文献   

7.
Attempts were made to detect porcine thrombocyte antibodies by three techniques. No antibodies were detected by immunodiffusion; hetero-antibodies were detected by both the fluorescent antibody and thrombo-agglutination techniques; but iso-antibodies were only detected by thrombo-agglutination. With the latter, however, there were ill-defined end-points which made the interpretation of negative results difficult. It was therefore suitable only for positive reactions of strong avidity.  相似文献   

8.
1) Production of tetanus antitoxin in rabbits and monkeys was followed by passive hemagglutination (HA) and toxin-neutralization (TN) tests. The HA activity was observed in both IgM and IgG in both animal species. 2) In rabbits, IgM antitoxin was detected as early as in 7 days, reached the maximum titer in 10--14 days, and disappeared in 3 weeks after the primary immunization. Antitoxin of IgG class was detected in 10 days, and increased gradually. The ratio of HA/TN titers ("serum ratio") was high at an early stage of primary immunization and approached the unity in 3--4 weeks. Unlike the case of guinea pigs, IgM was found to contribute greatly to this high level of ratio. Besides, most rabbits produced IgG antitoxin of high ratios at early stages of immunization. 3) The immune response of monkeys showed a pattern very similar to that of rabbits except a few days' delay in the time course of antitoxin titers. No IgG antitoxin with a high serum ratio was demonstrated. Therefore, the high serum ratio of early sera could be accounted for mainly by IgM. 4) In response to the secondary immunization, no IgM antitoxin was detected in either animal species. 5) No definite correlation between serum ratio and avidity in terms of "dilution ratio" was demonstrated. However, both the dilution ratio and serum ratio were high at an early stage of immunization and gradually decreased, though the magnitudes of the ratios were variable depending on individual animals.  相似文献   

9.
Chemostat-cultured Clostridium perfringens ATCC 3624 and NCTC 10240, and a nonsporulating mutant strain, 8-5, produced enterotoxin in the absence of sporulation when cultured in a chemically defined medium at a 0.084-h-1 dilution rate at 37 degrees C. The enterotoxin was detected by serological and biological assays. Examination of the chemostat cultures by electron microscopy did not reveal sporulation at any stage. The culture maintained enterotoxigenicity throughout cultivation in a continuous system. The enterotoxin was detected in batch cultures of each strain cultivated in fluid thioglycolate medium and a chemically defined medium. No heat-resistant or light-refractile spores were detected in batch cultures during the exponential growth.  相似文献   

10.
Human serum was assayed for the presence of a nuclease that can hydrolyse double stranded RNA. The synthetic RNA duplex polyI-polyC was used as substrate. No activity was detected in unfractionated or fractionated human serum.  相似文献   

11.
The genetic polymorphism of eight red cell enzymes was analyzed in four population samples from the two easternmost islands of the Canary Archipelago. No heterogeneity was detected within the islands, but differences between them were of the same magnitude as those found between the islands and the Spanish mainland. The presence of the African G6PD-A+ and the rare G6PD-Gc alleles seems to be a characteristic of all Canarian populations studied.  相似文献   

12.
Experiments were carried out to clarify the sites of action of beta-adrenergic agonists in skeletal muscle microsomes. Microsomes were fractionated into longitudinal reticulum, terminal cisternae, and isolated transverse tubules. Transverse tubules were selectively labeled and tracked with [3H]ouabain. beta-adrenergic receptor was identified by [3H]dihydroalprenolol binding. Assays of beta-adrenergic receptor, adenylate cyclase, and protein kinase-stimulated phosphorylation showed: 1) beta-adrenergic receptor was detected in transverse tubules with a receptor density of 0.61 pmol/mg of protein. No significant binding was detected in longitudinal reticulum or in terminal cisternae. 2) Isoproterenol-stimulated adenylate cyclase was present in microsomes but was similarly confined to the transverse tubular fraction. The activity of F- stimulated cyclase in transverse tubules was 2.3 nmol/mg of protein/min. 3) No phosphorylation of microsomes by cyclic AMP and protein kinase could be detected. We conclude that the action of epinephrine on skeletal muscle is mediated through receptors and adenylate cyclase in the external membrane.  相似文献   

13.
Physiology of lysine permeases in Saccharomycopsis lipolytica.   总被引:1,自引:1,他引:0       下载免费PDF全文
Two active lysine transport systems were detected in Saccharomycopsis lipolytica. No excretion of lysine out of the cells could be obtained, even by chasing with L-lysine or by poisoning with sodium azide. The kinetic properties of one of the permeases, the high-affinity lysine permease, were studied in detail. Its Km was 1.91 +/- 0.23 X 10(-5) M. It proved highly specific, the only potent competitive inhibitors being (i) arginine and its analogs L-canavanine and L-ornithine, and (ii) the lysine analogs L-5 aminoethylcysteine and L-4,5-transdehydrolysine. It is suggested that the high-affinity lysine permease is common to L-lysine, L-ornithine, and L-arginine. The other amino acids tested behaved as noncompetitive inhibitors. The variation of uptake during a growth cycle was studied on ammonia-rich, ammonia-poor, and ammonia-free media. In each case, the uptake exhibited a peak in the early exponential growth phase. No new permease activity was detected during the lag phase or the stationary phase. Ammonia ions competitively inhibited the uptake and also decreased the Vmax value.  相似文献   

14.
Cross-linking of the proteins in the outer membrane of Escherichia coli.   总被引:15,自引:0,他引:15  
1. The organization of the proteins in the outer membrane of Escherichia coli was examined by the use of cross-linking agents and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Treatment of protein A-peptidoglycan complexes with dithiobis(succinimidyl propionate) or glutaraldehyde produced the dimer, trimer, and higher oligomers of protein A. Both forms of this protein, proteins A1 and A2, produced similar cross-linking products. No cross-linking of protein A to the peptidoglycan was detected. 2. The proteins of the isolated outer membrane varied in their ease of cross-linking. The heat-modifiable protein, protein B, was readily cross-linked to give high molecular weight oligomers, while protein A formed mainly the dimer and trimer under the same conditions. The pronase resistant fragment, protein Bp, derived from protein B was not readily cross-linked. No linkage of protein A to protein B was detected. 3. Cross-linking of cell wall preparations, consisting of the outer membrane and peptidoglycan, showed that protein B and the free form of the lipoprotein, protein F, could be linked to the peptidoglycan. A dimer of protein F, and protein F linked to protein B, were detected. 4. These results suggest that specific protein-protein interactions occur in the outer membrane.  相似文献   

15.
The regulation mechanism governing the xylanolytic activity in the strain Cellulomonas sp. IIbc was studied. High levels of activity were detected during the cultivation on cellulose as the only carbon source. No activity was produced with glucose, xylose or cellobiose cultures, but in the last one, the synthesis was de-repressed when the sugar concentration dropped to 0.2%. The activity was not inhibited by glucose, cellobiose and xylose up to 1% concentration. A basal constitutive synthesis was detected in nutrient broth cultures. At the same time, xylose and cellobiose acted as inducers of the xylanase activity.  相似文献   

16.
Freshwater hyphomycete communities in four streams were sampled by filtration of water samples, trapping conidia in artificial foam, and examination of alder leaf pack baits and random sampling of naturally occurring submerged leaves. No two communities of freshwater hyphomycetes detected by different sampling techniques used singly in a stream showed 100% similarity. Based on relative frequency values, the same 10 top-ranking species in a stream were detected by artificial foam trap and on the baited leaves. These species differed in ranking, and the community in artificial foam was riche than on baited leaves. Of the various communities detected by different sampling techniques used singly or in combination, those detected by artificial foam trap or a combination of this technique with leaf baiting or with leaf baiting and randomly sampled leaves or filtration showed the highest similarity to the total community based on data generated using four sampling techniques simultaneously.This work was conducted under Grant No. PSF Project Environment 3 from the Pakistan Science Foundation.  相似文献   

17.
The karyotypes of two species of baboons, Papio papio and P. anubis, and of two species of Macaca, M. mulatta and M. fascicularis, are compared after the use of numerous banding techniques. No difference was detected between the karyotype of the two Papio species. However, a minor change in the T-staining of a short segment, probably heterochromatic, could be detected between the Papio species and M. mulatta. A paracentric inversion exists between these three and M. fascicularis. These karyotypes are briefly compared with those of the Pongidae and man. The value of the karyotypic criteria and of the methods used for taxonomy is discussed.  相似文献   

18.
Segregation analysis of 996 families in which the gene for beta-thalassemia was segregating showed no distortion of expected Mendelian ratios. No appreciable frequency of sporadic cases was detected. It was suggested that segregation distortion is not a mechanism which contributes to the maintenance of polymorphism in the beta-thalassemia system in the population of the Ferrara area.  相似文献   

19.
Intrathecal synthesis of interferon in the absence of viral or bacterial infection was detected during the occurrence of neurological complications in two patients with systemic lupus erythematosus. The interferons displayed characteristics similar to those observed in the sera of patients with the disease. No interferon inducing activity was detected in the cerebrospinal fluid or serum of the two patients. These observations support the hypothesis of a localised mechanism of interferon induction in systemic lupus erythematosus which includes the interaction of lymphocytes with damaged tissues.  相似文献   

20.
Antiserum directed against methionine enkephalin (metenkephalin) was used to determine its anatomical distribution in rat brain. Cross reactivity of that antiserum was not detectable against leucine enkephalin (leu-enkephalin), β-lipotropin (β-LPH), β-endorphin or assorted peptide fragments of met-enkephalin; alpha-endorphin was 370 times less active than met-enkephalin. The localization of met-enkephalin was carried out in the presence of excess leu-enkephalin and yet could be blocked with equal amounts of met-enkephalin. Met-enkephalin was detected in several structures in the spinal cord, medulla, pons, mesencephalon, diencephalon and telencephalon. No met-enkephalin was detected in cerebellum or cerebral cortex.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号