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41.
Pedro J. N. Silva Richard K. Koehn Walter J. Diehl III Robin P. Ertl Elaine B. Winshell Mauro Santos 《Biochemical genetics》1989,27(7-8):451-467
Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism
in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux
was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained.
GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%)
genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties
that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one
of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level.
The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto
Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages
of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form
of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science
Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University
of New York at Stony Brook.
On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal. 相似文献
42.
Armando Menendez-Pelaez Alberto Martinez-Telleria Jose A. Vega Carmen Coalla Russel J. Reiter 《The Histochemical journal》1989,21(3):125-130
Summary Monoamine oxidase (MAO) and alcohol dehydrogenase (AD) activities were studied histochemically in the Syrian hamster Harderian gland using tryptamine as substrate and Nitroblue Tetrazolium as the final electron acceptor. No dark: light-related changes were observed. Male type I secretory cells showed an intense MAO reaction. Female type I cells exhibited a moderate MAO activity. Both male and female glands showed a moderate/intense AD-positive reaction. Male type II cells were lacking MAO and AD activities. MAO activity found in the hamster Harderian glands corresponded mainly to MAO type A since treatment with chlorgyline (0.01, 0.1 and 0.5mm) totally inhibited it. The possible role of these two enzymes in Harderian gland indolalkylamine metabolism is discussed. 相似文献
43.
Enrique Palacián Pedro J. González Manuel Piñeiro Francisco Hernández 《Molecular and cellular biochemistry》1990,97(2):101-111
Dissociation of protein-containing structures by modification of protein amino groups with dicarboxylic acid anhydrides is a mild procedure which, in some cases, offers advantages over treatment with alternative dissociating agents, such as urea, guanidine hydrochloride, detergents, high ionic strength, and extremes of pH: In addition to dissociating multimeric proteins and protein aggregates, dicarboxylic acid anhydrides are effective dissociating agents for membrane-bound proteins and nucleoprotein particles. With most dicarboxylic acid anhydrides reviewed, the introduced reagent residues can be eliminated under moderate acid conditions, which allows the purification of unmodified individual components, and the use of disassembly-reconstitution systems valuable for investigating the structural and functional roles played by the individual components of complex particles:Each reagent can be suitable for a particular purpose, depending on the required specificity of the modification and stability of the modified groups: The stability of the acylated amino groups ranges from the very stable succinylated amino groups to the very labile acylation obtained with dimethylmaleic anhydride: Between these extremes, the stability of the modified amino groups decreases stepwise in the following order: maleic, exo-cis-3,6-endoxo-4-tetrahydrophthalic, citraconic, and 3,4,5,6-tetrahydrophthalic anhydride. With respect to the selectivity of the produced modification, little or no modification of hydroxyamino acid and cysteine residues has been observed with dimethylmaleic, exo-cis-3,6-endoxo-4-tetrahydrophthalic, and 3,4,5,6-tetrahydrophthalic anhydrides: With the other reagents, the extent of modification of hydroxyamino acid residues increases in the order citraconic, maleic and succinic anhydride: Citraconic and maleic anhydrides can produce irreversible modification of cysteine residues, the reactivity of sulfhydryl groups being higher with maleic anhydride: 相似文献
44.
Prenatal diagnosis of familial amyloidotic polyneuropathy: evidence for an early expression of the associated transthyretin methionine 30 总被引:3,自引:0,他引:3
Maria Rosário Almeida Isabel Longo Alves Yoshiuki Sakaki Pedro Pinho Costa Maria João M. Saraiva 《Human genetics》1990,85(6):623-626
Summary Transthyretin methionine 30 (TTR Met 30), which is associated with familial amyloidotic polyneuropathy, originates in a single base substitution (A for G) in the second exon of the TTR gene. This autosomal dominant disease can be diagnosed by RFLP analysis of NsiI-digested DNA. The amplification of DNA by PCR improves the diagnosis method, making it suitable for prenatal diagnosis. Using PCR-amplified DNA, prenatal diagnosis of two at-risk fetuses was performed. Control Met 30 and normal DNA (either genomic or produced by site directed mutagenesis) were processed in parallel. The diagnosis was made by hybridization with allele-specific oligonucleotide probes, and later confirmed by screening of the mutant protein in the amniotic fluid and, when possible, in the sera from the newborns. TTR Met 30 was detected in the amniotic fluid of a positive fetus whose father was the carrier of the mutation. This indicates that the mutant protein is expressed very early in development. 相似文献
45.
The daily and seasonal distribution of airborne fungal particles was recorded in a high altitude tropical zone. Sampling was
carried out in the southern part of Mexico City. An Andersen air sampler was used over a period of six months. Ten minutes
sampling for each set of plates was done at fixed schedule: 07:30, 14:00 and 19:00 hours. The sampler was placed 10 m above
the ground. Daily variation was found to be associated with the season, weather and atmospheric stability. The highest value
of mold counts (3195 CFU m−3) was recorded in the evening on October, a transitional month between the rainy and the dry seasons, the lowest (45 CFU m−3) at noon during the rainy season. Mold counts were significantly correlated with temperature, having negative signs both
in the morning and at noon, and being positive in the evening. The abundance of only three genera was recorded.Cladosporium, was isolated more frequently, and its abundance at 14:00 h was of 38%;Alternaria represented 4.0%, at 14:00 h, andAspergillus 3.0% at 7:30 h. Fifteen species belonging to the latter genera were identified and most of them are considered as opportunistic
molds of clinical significance. 相似文献
46.
Jose Jacob 《Molecular and cellular biochemistry》1988,84(1):97-103
Summary Effects of Ca2+ ionophores, A23187 and lasalocid, on superoxide anion generation by chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine methyl ester, in rabbit peritoneal exudate neutrophils were studied. The ionophores by themselves did not activate superoxide anion generation in these neutrophils. When preincubated with the cells for 2 min, both the ionophores inhibited superoxide generation induced by chemotactic peptide. The inhibition was present even in the absence of extracellular Ca2+ and the inhibition was better then. Lasalocid produces a dose-dependent chlortetracycline fluorescence decrease response in neutrophils loaded with chlortetracycline. This response is independent of extracellular Ca2+ concentration and is related to release of Ca2+ from intracellular storage sites. The dose-range at which lasalocid gives this response is same as the dose-range at which it causes inhibition of superoxide response. It may be concluded that the inhibition of superoxide generation by these ionophores is correlated to intracellular Ca2+ modulation.Abbreviations FMLP
Formyl-Methionyl-Leucyl-Phenylalanine methyl ester 相似文献
47.
Jose L. Vega Vicki L. Holmberg Edgar C. Clausen James L. Gaddy 《Archives of microbiology》1988,151(1):65-70
Intrinsic growth and substrate uptake parameters were obtained for Peptostreptococcus productus, strain U-1, using carbon monoxide as the limiting substrate. A modified Monod model with substrate inhibition was used for modeling. In addition, a product yield of 0.25 mol acetate/mol CO and a cell yield of 0.034 g cells/g CO were obtained. While CO was found to be the primary substrate, P. productus is able to produce acetate from CO2 and H2, although this substrate could not sustain growth. Yeast extract was found to also be a growth substrate. A yield of 0.017 g cell/g yeast extract and a product yield of 0.14 g acetate/g yeast extract were obtained. In the presence of acetate, the maximum specific CO uptake rate was increased by 40% compared to the maximum without acetate present. Cell replication was inhibited at acetate concentrations of 30 g/l. Methionine was found to be an essential nutrient for growth and CO uptake by P. productus. A minimum amount of a complex medium such as yeast extract (0.01%) is, however, required. 相似文献
48.
Effects of the administration of cadmium and zinc on the concentration of zinc in the thymus of rats
Paloma Huerta Paloma Galan Alberto J. Alcala Bartolome Ribas Jose M. Teijon 《Biological trace element research》1988,18(1):95-103
The zinc content of thymus glands of male Wistar rats has been determined during five weeks of treatment with ZnCl2 and CdCl2, and compared with a group of control rats. THymus gland extracts were chromatographed on columns of Sephadex G-75 and the zinc content of the one hundred fractions obtained were determined by atomic absorption spectrophotometry. The rats treated with ZnCl2 showed an increase in the thymus concentration of zinc bound to high and low molecular weight proteins. The rats treated with CdCl2 showed an increase in zinc concentration, as opposed to the control group, during the first three weeks of treatment, and thereafter show a toxic effect of cadmium on the gland, with ulterior regression of the latter, and a decrease in the concentration of zinc. 相似文献
49.
Occurrence of a Large Ca2+ -Independent Release of Glutamate During Anoxia in Isolated Nerve Terminals (Synaptosomes) 总被引:2,自引:0,他引:2
Isolated rat cerebral cortical synaptosomes made anoxic by addition of cyanide developed an inhibition of the Ca2+-dependent release of glutamate 2 min after the addition of the metabolic inhibitor when the intrasynaptosomal ATP/ADP ratio decreased below 1.7. In contrast, cyanide induced a continuous efflux of glutamate through a Ca2+-independent pathway that accounted for the release of 25% of total intrasynaptosomal glutamate in 5 min. The results suggest that a Ca2+-independent release of glutamate could be implicated in the neurotoxic action of this amino acid during anoxia. 相似文献
50.
Summary A systematic study was made of the action of 4-acetamido-4-isothiocyanostilbene-2,2-disulfonic acid (SITS) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) on active Ca2+ transport of human erythrocytes. Pumping activity was estimated in inside-out vesicles (IOV's) by means of Ca2+-selective electrodes or use of tracer45Ca2+. The stilbenes exhibited an approximately equal inhibitory potency and their action could be overcome by carbonyl cyanidep-trifluoromethoxyphenylhydrazone (FCCP) at low but not at high stilbene concentrations. In the absence of DIDS. Ca2+ transport was not affected upon addition of valinomycin, but it was appreciably reduced when vesicles were preincubated with low DIDS concentrations. Such an effect was strictly dependent on the external K+ concentration and it was abolished when valinomycin was added together with FCCP. Similar results were obtained using IOV's prepared from intact cells which had been previously exposed to the stilbene. The findings clearly demonstrate the presence in human red cells of a partially electrogenic Ca2+ pump, exchanging one Ca2+ ion for one proton. 相似文献