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911.
1. A particulate enzyme fraction and an acetone powder preparation from cucumber fruits cleaved 9- and 13-hydroperoxyoctadecadienoic acids to form volatile aldehydes and oxoacid fragments. 2. From the 9-hydroperoxide, the major volatile fragments were cis-3-nonenal and trans-2-nonenal using particulate enzyme and acetone powder preparations, respectively. 3. Hexanal was the only significant volatile fragment from the 13-hydroperoxide. 4. The particulate enzyme system was equally effective on both 9- and 13-hydroperoxide isomers and was fully active under anaerobic conditions and at pH 6.4. 5. An enzymic pathway for the biogenesis of hexanal, cis-3- and trans-2-nonenal (components of the characteristic flavour volatiles of cucumber) from linoleic acid is proposed. This involves the sequential activity of lipoxygenase, hydroperoxide cleavage and cis-3-: trans-2-enal isomerase enzymes. 相似文献
912.
A sensitive and simple method for the quantitation of human DNA is described. This method is based on probe hybridization to a human alpha satellite locus, D17Z1. The biotinylated probe is hybridized to sample DNA immobilized on nylon membrane. The subsequent binding of streptavidin-horseradish peroxidase to the bound probe allows for chemiluminescent detection using a luminol-based reagent and X-ray film. Less than 150 pg of human DNA can easily be detected with a 15 minute exposure. The entire procedure can be performed in 1.5 hours. Microgram quantities of nonhuman DNA have been tested and the results indicate very high specificity for human DNA. The data on film can be scanned into a computer and a commercially available program can be used to create a standard curve where DNA quantity is plotted against the mean density of each slot blot signal. The methods described can also be applied to the very sensitive determination of quantity and quality (size) of DNA on Southern blots. The high sensitivity of this quantitation method requires the consumption of only a fraction of sample for analysis. Determination of DNA quantity is necessary for RFLP and many PCR-based tests where optimal results are obtained only with a relatively narrow range of DNA quantities. The specificity of this quantitation method for human DNA will be useful for the analysis of samples that may also contain bacterial or other non-human DNA, for example forensic evidence samples, ancient DNA samples, or clinical samples. 相似文献
913.
914.
The ataxia-telangiectasia gene (ATA) on chromosome II is distinct from the ETS-1 gene. 总被引:2,自引:2,他引:0
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P Concannon U Malhotra P Charmley J Reynolds K Lange R A Gatti 《American journal of human genetics》1990,46(4):789-794
We have studied the segregation of an RFLP detected with a human ETS-1 genomic probe in 25 families containing members affected with ataxia-telangiectasia (AT) and in 27 families from the Centre d'Etude du Polymorphisme Humain (CEPH) panel. We have recently mapped a gene for AT to 11q22-23 by linkage to the markers THY1 and D11S144. Multipoint linkage analysis of the CEPH families indicated that ETS-1 is located on chromosome 11q approximately 19.2 centimorgans telomeric to THY1. Analysis of the segregation of ETS-1 alleles in AT families yields strongly negative LOD scores, excluding an AT gene from a region extending 15 cM to either side of ETS-1. Multipoint mapping of ETS-1, D11S144, THY1, and AT also excludes the possibility that an AT gene is telomeric to ETS-1. 相似文献
915.
Colobus type C virus: molecular cloning of unintegrated viral DNA and characterization of the endogenous viral genomes of Colobus. 总被引:4,自引:2,他引:2
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E H Birkenmeier T I Bonner K Reynolds G H Searfoss G J Todaro 《Journal of virology》1982,41(3):842-854
The unintegrated viral DNA intermediates of colobus type C virus (CPC-1) were isolated from infected human cells that were permissive for viral growth. There were two major species of DNA, linear molecules with two copies of the long terminal repeat and relaxed circles containing only a single long terminal repeat. In addition, there was a minor species (approximately 10%) composed of relaxed circles with two copies of the long terminal repeat. A restriction endonuclease map of the unintegrated DNA was constructed. The three EcoRI fragments of circular CPC-1 DNA were cloned in the EcoRI site of lambda gtWES . lambda B and then subcloned in the EcoRI site of pBR322. Using these subgenomic fragments as probes, we have characterized the endogenous viral sequences found in colobus cellular DNA. They are not organized in tandem arrays, as is the case in some other gene families. The majority of sequences detected in cellular DNA have the same map as the CPC-1 unintegrated DNA at 17 of 18 restriction endonuclease sites. There are, however, other sequences that are present in multiple copies and do not correspond to the CPC-1 map. They do not contain CPC-1 sequences either in an altered form or fused to common nonviral sequences. Instead, they appear to be derived from a distinct family of sequences that is substantially diverged from the CPC-1 family. This second family of sequences, CPC-2, is also different from the sequences related to baboon endogenous type C virus that forms a third family of virus-related sequences in the colobus genome. 相似文献
916.
917.
The presence of a sodium-dependent, saturable uptake process is described in basolateral membranes of rat renal cortex for L-glutamine. Concentration-dependence studies indicate the presence of multiple transport systems withK
m
1 of 0.032 mM and V1 of 0.028 nmol/mg of protein per min, andK
m
2 of 17.6 mM and V2 of 17.6 nmol/mg of protein per min. Lysine completely inhibits the high-affinity, low-capacityK
m system and partially inhibits the low-affinity, high-capacity system. Cystine and other dibasic amino acids also affect glutamine uptake. 相似文献
918.
U. Trechsel G. Dew G. Murphy J.J. Reynolds 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1982,720(4):364-370
Collagenase secretion was studied in cultures of rabbit articular chondrocytes. Differentiation of the cells was assessed by characterizing the type of 3H-labelled collagen produced during treatment with (1) conditioned media from rabbit peritoneal macrophages and human blood mononuclear cells, and (2) with retinol, a potent cartilage resorbing agent in tissue culture. Conditioned media stimulated collagenase secretion. Total collagen synthesis was reduced due to a decrease of synthesis of α1 chains; the amount of α2 chains synthesized was unchanged. This is thought to be due to a reduction in type II synthesis. Retinol did not stimulate collagenase secretion. Total collagen synthesis was reduced by retinol. α2 chain synthesis, however, was significantly increased, suggesting a switch of collagen synthesis in favor of type I collagen and, therefore, dedifferentiation. These results demonstrate that dedifferentiation of chondrocytes with respect to collagen synthesis is not necessarily associated with a stimulation of collagenase secretion. 相似文献
919.
Tracey A. Chatterton C. Hugh Reynolds Norman R. Lazarus Christopher I. Pogson 《The Biochemical journal》1982,204(2):605-608
Pyruvate kinase in rat pancreatic islets was characterized immunologically and kinetically. It is concluded that this activity is predominantly if not totally of the M2 type. 相似文献
920.
A rapid fluorometric assay for erythrocyte pyridoxal kinase 总被引:1,自引:0,他引:1