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1.
Plasminogen activator and collagenase production by cultured capillary endothelial cells 总被引:33,自引:17,他引:16
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Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells. 相似文献
2.
Isolates of Bacillus subtilis that had been presumed to carry the cysA14 lesion have been studied. Our data indicate that these strains contain four mutations, all of which are linked by transformation and lie in the region of the ribosomal markers. The requirement for cysteine results from a defective serine transacetylase that is coded for by the cysA locus. Therefore, these mutants grow only in the presence of cysteine but not with sulfate, sulfite, or sulfide as the sole source of sulfur. A second genetic lesion (css) can be recognized by an increased sensitivity to the amino acid L-cysteine. The inhibited enzyme(s) has not been determined but inhibition is overcome by a mixture of eight amino acids. The third mutation (hts) results in the overproduction and excretion of hydrogen sulfide. This compound appears to be produced from cysteine by the enzyme cysteine desulfhydrylase and not by an increased activity of the sulfate-reductive pathway. This locus presumably codes for a regulatory element involved in the control of cysteine desulfhydrylase. The fourth mutation (cym) is not well characterized biochemically but results in a requirement for cysteine or methionine. The following order of these mutations has been established by transformation studies: hts, cysA, css, cym. The generally poor growth of these mutants in minimal-salts glucose media supplemented with cysteine can now be explained by these observations. The cysA14 mutants not only require an amino acid that is itself inhibitory to growth but they also overproduce the highly toxic compound hydrogen sulfide. 相似文献
3.
A common polygenic basis for quinine and PROP avoidance in mice 总被引:3,自引:2,他引:1
Inbred strains of mice (Mus musculus) differ greatly in ability to taste
various bitter compounds. For some compounds, the differences result from
allelic variation at a single locus. However, segregation patterns
incompatible with monogenic inheritance have been found for quinine
avoidance. The Soa bitter sensitivity locus exerts some influence on this
phenotype, but an unknown number of other loci also contribute. Relative
avoidance patterns for quinine sulfate in panels of naive inbred strains
resembled avoidance patterns for 6-n-propyl-2- thiouracil (PROP),
suggesting a common genetic basis. In particular, C57BL/6J mice strongly
avoided both 0.1 mM quinine sulfate and 1 mM PROP in two-bottle preference
tests, whereas C3H/HeJ mice were indifferent to both. Therefore, 12 BXH/Ty
recombinant inbred strains, derived from these strains, were tested with
both solutions to begin identification of the unknown bitter loci. Naive
mice were tested for four consecutive days with each compound (order
counterbalanced). Some BXH/Ty strain means resembled those of the parent
strains, but others were intermediate. This indicated recombination among
loci affecting avoidance, and therefore polygenic inheritance. The strain
means were highly correlated across compounds (r = 0.98), suggesting that
the same polygenes controlled both phenotypes. The BXH/Ty means for both
compounds were then compared with the strain genotypes at 212 chromosome
position markers distributed throughout the genome. Eight markers on five
chromosomes (3, 6, 7, 8 and 9) yielded significant correlations. Six of the
markers were correlated with both phenotypes, again suggesting common
polygenic inheritance. The marker with the highest correlation was Prp,
tightly linked to Soa on chromosome 6. The correlated marker regions likely
contain quantitative trait loci affecting bitter avoidance. The phenotypic
similarity of PROP to quinine, rather than to phenylthiourea, apparently
stemming from a common polygenic basis, indicates a difference between mice
and humans in gustatory organization related to bitters.
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4.
Increased levels of dihydrofolate reductase in rifampin-resistant mutants of Bacillus subtilis.
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Several independent, spontaneous rifampin-resistant mutants of Bacillus subtilis were isolated and found to have an increased resistance to trimethoprim, an inhibitor of dihydrofolate reductase. This increased resistance in the rif mutants was the result of a specific threefold increase in the activity of dihydrofolate reductase, since six other enzymes examined remained unchanged. This increased level of dihydrofolate reductase and the trimethoprim resistance were cotransformed (100%) with the rif marker. These results suggest that the RNA polymerase is altered in its recognition of the gene that specifies dihydrofolate reductase. 相似文献
5.
Carla DB Fernandez Fernanda F Bellentani Glaura SA Fernandes Juliana E Perobelli Ana Paula A Favareto André F Nascimento Antonio C Cicogna Wilma DG Kempinas 《Reproductive biology and endocrinology : RB&E》2011,9(1):32
Background
Obesity is rapidly becoming a worldwide epidemic that affects children and adults. Some studies have shown a relationship between obesity and infertility, but until now it remains controversial. Thus, the aim of the present study was to investigate the effect of high-fat diet-induced obesity on male reproductive parameters. 相似文献6.
Whitehouse DB; Tomkins J; Lovegrove JU; Hopkinson DA; McMillan WO 《Molecular biology and evolution》1998,15(4):456-462
The expanding molecular database provides unparalleled opportunities for
characterizing genes and for studying groups of related genes. We use
sequences drawn from the database to construct an evolutionary framework
for examining the important glycolytic enzyme phosphoglucomutase (PGM).
Phosphoglucomutase plays a pivotal role in the synthesis and utilization of
glycogen and is present in all organisms. In humans, there are three
well-described isozymes, PGMI, PGM2, and PGM3. PGM1 was cloned 5 years ago;
however, repeated attempts using both immunological approaches and
molecular probes designed from PGM1 have failed to isolate either PGM2 or
PGM3. Using a phylogenetic strategy, we first identified 47 highly
divergent prokaryotic and eukaryotic PGM-like sequences from the database.
Although overall amino acid identity often fell below 20%, the relative
order, position, and sequence of three structural motifs, the active site
and the magnesium-- and sugar-binding sites, were conserved in all 47
sequences. The phylogenetic history of these sequences was complex and
marked by duplications and translocations; two instances of transkingdom
horizontal gene transfer were identified. Nonetheless, the sequences fell
within six well-defined evolutionary lineages, three of which contained
only prokaryotes. Of the two prokaryotic/eukaryotic lineages, one contained
bacterial, yeast, slimemold, invertebrate, and vertebrate homologs to human
PGM1 and the second contained likely homologs to human PGM2. Indeed, an
amino acid sequence, derived from a partial human cDNA, that fell within
the second cross-kingdom lineage bears several characteristics expected for
PGM2. A third lineage may contain homologs to human PGM3. On a general
level, our phylogenetic-based approach shows promise for the further
utilization of the extensive molecular database.
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7.
Incorporation of axonally transported glycoproteins into axolemma during nerve regeneration 总被引:14,自引:4,他引:10
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The insertion of axonally transported fucosyl glycoproteins into the axolemma of regenerating nerve sprouts was examined in rat sciatic motor axons at intervals after nerve crush. [(3)H]Fucose was injected into the lumbar ventral horns and the nerves were removed at intervals between 1 and 14 d after labeling. To follow the fate of the “pulse- labeled” glycoproteins, we examined the nerves by correlative radiometric and EM radioautographic approaches. The results showed, first, that rapidly transported [(3)H]fucosyl glycoproteins were inserted into the axolemma of regenerating sprouts as well as parent axons. At 1 d after delivery, in addition to the substantial mobile fraction of radioactivity still undergoing bidirectional transport within the axon, a fraction of label was already associated with the axolemma. Insertion of labeled glycoproteins into the sprout axolemma appeared to occur all along the length of the regenerating sprouts, not just in sprout terminals. Once inserted, labeled glycoproteins did not undergo extensive redistribution, nor did they appear in sprout regions that formed (as a result of continued outgrowth) after their insertion. The amount of radioactivity in the regenerating nerves decreased with time, in part as a result of removal of transported label by retrograde transport. By 7-14 d after labeling, radioautography showed that almost all the remaining radioactivity was associated with axolemma. The regenerating sprouts retained increased amounts of labeled glycoproteins; 7 or 14 d after labeling, the regenerating sprouts had over twice as much of radioactivity as comparable lengths of control nerves or parent axons. One role of fast axonal transport in nerve regeneration is the contribution to the regenerating sprout of glycoproteins inserted into the axolemma; these membrane elements are added both during longitudinal outgrowth and during lateral growth and maturation of the sprout. 相似文献
8.
Biochemical-genetic study of the first enzyme of histidine biosynthesis in Salmonella typhimurium: substrate and feedback binding regions. 总被引:3,自引:0,他引:3
Twenty-five strains of Salmonella typhimurium containing different mutations in the first gene of histidine biosynthesis were studied to correlate regions of the genetic map with biochemical functions. These strains contained either missense, double-frameshift, or suppressed nonsense mutations, all of which resulted in altered, though active, enzymes. Each mutant enzyme was assayed for activity in the presence of varying concentrations of the feedback inhibitor L-histidine or the substrates ATP and 5-phosphoribosyl-1-pyrophosphate. The feedback properties and substrate kinetics of each mutant enzyme were compared to wild-type values, and these results indicated that the following functions were correlated with regions of the hisG gene: feedback inhibition in two general areas, including regions IA and IB and regions V, VI, and VII; ATP binding in two general areas, including regions IA, IB, and II and regions V, VI, and VII; and 5-phosphoribosyl-1-pyrophosphate binding in two general areas, including regions IB, II, and III and regions V and VI. 相似文献
9.
Melvyn Baez Jonathan D. Kursar Lisa A. Helton David B. Wainscott David L.G. Nelson 《Obesity (Silver Spring, Md.)》1995,3(Z4):441S-447S
Over the last several years the use of molecular cloning technology has revealed a vast diversity among serotonin (5-HT)receptors, where by what was previously thought to be a family of three pharmacologically defined classes of 5-HT receptors is actually composed of seven distinct subfamilies designated 5-HT1–7. The 5-HT1, 5-HT2, and 5-HT5 subfamilies currently consist of five, three and two subtypes respectively while the 5-HT3,5-HT4, 5-HT6, and 5-HT7 “subfamilies” have at present one subtype each. Fourteen separate genes encode 13 receptors which fall in the superfamily of G protein-coupled receptors and one ligand-gated ion channel receptor. Our lab has contributed to the elucidation of this subtype diversity by cloning the cDNAs from both rat and human encoding the 5-HT2B receptor. This receptor subtype is equally homologous (approximately 70%) to the 5-HT2A and 5-HT2C receptors when amino acids comprising the transmembrane domains are compared and is clearly the third member of the 5-HT2 subfamily. The 5-HT2B receptor has been shown to couple to phosphoinositide hydrolysis as do the other two members of this subfamily when expressed in AV12-664 cells. Limited pharmacological analyses indicated that both rat and human 5-HT2B receptors are similar but distinguishable. With one tantalizing exception, the mRNAs for these receptors appear to be similarly distributed within rat and human. The 5-HT2B receptor mRNA is not found in rat brain, whereas in human brain it has been identified in multiple regions. This later finding suggests that the 5-HT2B receptor may be serving a unique CNS function in man that is absent in rat. 相似文献
10.