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H. E. van de Baan L. A. M. Kuijpers W. P. J. Overmeer F. J. Oppenoorth 《Experimental & applied acarology》1985,1(1):3-10
The cause of parathion and propoxur resistance inTyphlodromus pyri was studied in a Dutch strain in which resistance was dependent on a semi-dominant gene. Activity of glutathione S-transferase and acetylcholinesterase and reaction rate of acetylcholinesterase with paraoxon and propoxur were measured in this resistant (R) and in a susceptible (S) strain. The R strain was 100-fold resistant to parathion and 2300-fold resistant to propoxur. A 36-fold reduction was found in rate of inhibition of acetylcholinesterase in the R strain for paraoxon, and a 14-fold reduction for propoxur. In combination with the monogenic nature of the resistance, this proves that the insensitivity of acetylcholinesterase is the cause of resistance. The rate constant of acetylcholinesterase inhibition at 25°C in the S and R strains was 1.5×105 and 4.2×103
M
–1 min–1 respectively for paraoxon, and 5.1×104 and 3.6×103
M
–1 min–1 for propoxur. There was no significant difference between the R and S strains in glutathione S-transferase activity. The R strain had a somewhat lower acetylcholinesterase activity than the S strain. 相似文献
3.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
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Removal of enteric viruses from surface water at eight waterworks in The Netherlands. 总被引:2,自引:1,他引:1 下载免费PDF全文
Eight waterworks in The Netherlands, which use surface water as their raw water source, were sampled repeatedly between November 1978 and June 1981. At five waterworks , 30 of 45 samples of raw water contained viruses. Of 55 samples of partially purified water, 11 were virus positive, including 8 after coagulation, sedimentation, and rapid sand filtration, 2 after storage, coagulation, sedimentation, transport chlorination, and rapid sand filtration, and 1 after storage in open reservoirs for 5 months. No viruses were detected in 100 samples of drinking water of 500 liters each from six waterworks . Most isolated viruses were typed, and a great variety of human enteroviruses were found, reflecting both pollution of raw water sources with sewage and vaccination with oral polio vaccine in neighboring countries. 相似文献
6.
Evolution of the V3 envelope domain in proviral sequences and isolates of human immunodeficiency virus type 1 during transition of the viral biological phenotype. 总被引:29,自引:21,他引:8 下载免费PDF全文
C L Kuiken J J de Jong E Baan W Keulen M Tersmette J Goudsmit 《Journal of virology》1992,66(7):4622-4627
The third variable domain (V3) of the envelope gene of human immunodeficiency virus type 1 contains a major neutralization epitope and determinants of syncytium-inducing (SI) capacity and replication rate (reviewed by J. P. Moore and P. L. Nara, AIDS Suppl. 2:S21-S33, 1991). Sequences were generated from DNA of samples taken 3 months apart over a period of 24 and 30 months from peripheral blood mononuclear cells (PBMC) of two individuals, both before and after cocultivation with uninfected donor PBMC. The isolated virus shifted from the non-syncytium-inducing (NSI) phenotype to the SI phenotype during the study period. This shift was associated with distinct changes in the V3 domain in both patients. The association of the phenotype shift with the V3 sequence changes was confirmed by construction of viruses with chimeric V3 loops. The shift from NSI- to SI-associated V3 variants was also seen in the uncultured PBMC of both patients, but not until 3 and 9 months after the detection of SI virus in culture. In the samples of uncultured PBMC DNA, several subgroups of sequences were found, indicating that the process of evolution may not be gradual and that several distinct populations can coexist. The paucity of intermediate sequences indicated that strong selection pressure was exerted on this part of the envelope. The early emergence of disease-associated SI variants in cultured material indicates that virus culture may have relevance for the in vivo situation. 相似文献
7.
Production and localization of beta-fructosidase in asynchronous and synchronous chemostat cultures of yeasts. 总被引:1,自引:0,他引:1 下载免费PDF全文
R J Rouwenhorst A A van der Baan W A Scheffers J P Van Dijken 《Applied microbiology》1991,57(2):557-562
In synchronized continuous cultures of Saccharomyces cerevisiae CBS 8066, the production of the extracellular invertase (EC 3.2.1.26) showed a cyclic behavior that coincided with the budding cycle. The invertase activity increased during bud development and ceased at bud maturation and cell scission. The cyclic changes in invertase production resulted in cyclic changes in amounts of invertase localized in the cell wall. However, the amount of enzyme invertase present in the culture liquid remained constant throughout the budding cycle. Also, in asynchronous continuous cultures of S. cerevisiae, the production and localization of invertase showed significant fluctuation. The overall invertase production in an asynchronous culture was two to three times higher than in synchronous cultures. This could be due to more-severe invertase-repressive conditions in a synchronous chemostat culture. Both the intracellular glucose-6-phosphate concentration and residual glucose concentration were significantly higher in synchronous chemostat cultures than in asynchronous chemostat cultures. In the asynchronous and synchronous continuous cultures of S. cerevisiae, about 40% of the invertase was released into the culture liquid; it has generally been believed that S. cerevisiae releases only about 5% of its invertase. In contrast to invertase production and localization in the chemostat cultures of S. cerevisiae, no significant changes in inulinase (EC 3.2.1.7) production and localization were observed in chemostat cultures of Kluyveromyces maxianus CBS 6556. In cultures of K. marxianus about 50% of the inulinase was present in the culture liquid. 相似文献
8.
9.
MARIA JOSÉ ASINS IRENE VILLALTA MOHAMED M. ALY RAQUEL OLÍAS PAZ ÁLVAREZ DE MORALES RAÚL HUERTAS JUN LI NOELIA JAIME‐PÉREZ ROSARIO HARO VERÓNICA RAGA EMILIO A. CARBONELL ANDRÉS BELVER 《Plant, cell & environment》2013,36(6):1171-1191
The location of major quantitative trait loci (QTL) contributing to stem and leaf [Na+] and [K+] was previously reported in chromosome 7 using two connected populations of recombinant inbred lines (RILs) of tomato. HKT1;1 and HKT1;2, two tomato Na+‐selective class I‐HKT transporters, were found to be closely linked, where the maximum logarithm of odds (LOD) score for these QTLs located. When a chromosome 7 linkage map based on 278 single‐nucleotide polymorphisms (SNPs) was used, the maximum LOD score position was only 35 kb from HKT1;1 and HKT1;2. Their expression patterns and phenotypic effects were further investigated in two near‐isogenic lines (NILs): 157‐14 (double homozygote for the cheesmaniae alleles) and 157‐17 (double homozygote for the lycopersicum alleles). The expression pattern for the HKT1;1 and HKT1;2 alleles was complex, possibly because of differences in their promoter sequences. High salinity had very little effect on root dry and fresh weight and consequently on the plant dry weight of NIL 157‐14 in comparison with 157‐17. A significant difference between NILs was also found for [K+] and the [Na+]/[K+] ratio in leaf and stem but not for [Na+] arising a disagreement with the corresponding RIL population. Their association with leaf [Na+] and salt tolerance in tomato is also discussed. 相似文献
10.