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61.
Henry A. F. Stephens Robert W. Vaughan Lazaros I. Sakkas Ken I. Welsh Gabriel S. Panayi 《Immunogenetics》1989,30(3):149-155
Despite extensive analysis of the incidence ofHLA-DR andHLA-DQ allele frequencies in defined autoimmune disease groups, there is very little information available onHLA-DP allele frequencies. This is largely becauseHLA-DP typing has until recently been restricted to primed lymphocyte typing (PLT). However, allelic polymorphism of theHLA-DP subregion can now be studied by Southern blot analysis or genotyping withDPA1 andDPB1 probes. By direct counting of allele-specific DNA fragments, we have analyzed the frequencies of five majorDP genotypes (DPw1, DPw2, DPw3/6, DPw4, andDPw5), in a large number of Caucasoid rheumatoid arthritis (RA) patients (n=74), and controls (n=91). The predicted frequency
ofDP alleles in both patient and control groups was comparable to PLT-determinedDP allele frequencies in normal Caucasoids. However, the gene frequency ofDPw4 was increased in the RA patients, with 51% of the patients studied scoring asDPw4, 4 homozygotes. With the exception of one possible combination (DPw5 andDRw6) in the controls, no significant linkage disequilibrium was detected betweenDP andDR alleles in either patient or control groups. Thus the prevalence ofDPw4 in the RA patients is independent of any disease association with theDR loci, and may represent a new class II association with RA. 相似文献
62.
L. M. Popescu C. Cernescu I. I. Moraru St. N. Constantinescu F. Baltã M. Manciulea E. Brãiloiu L. Buzilã 《Bioscience reports》1989,9(5):531-539
A monospecific inhibitory antibody directed to phospholipase C (phosphoinositidase C) blocked the antiviral effect of human interferons alpha and beta when tested on human quiescent fibroblasts challenged with the vesicular stomatitis virus. This action was due to specific inhibition of polyphosphoinositide hydrolysis because (a) the F(ab)2 fragment of the antibody molecule was also inhibitory; (b) excess antibodies directed to phospholipase A2 and to a phosphatidylcholine-preferring phospholipase C did not have any inhibitory effect, and (c) the combination of 12-O-tetradecanoylphorbol-acetate and calcium ionophore A23187 had an interferon-like antiviral effect which was not influenced by the inhibitory anti-phospholipase C antibodies. To avoid an interferon-like effect due to induction of interferon by second messengers, Vero cells, which lack interferon biosynthesis, were also used. Liposomes containing inositol 1,4,5-triphosphate and 1-oleoyl-2-acetyl-rac-glycerol protected Vero cells against the infection with the vesicular stomatitis virus. These results taken together show that phosphoinositide-derived second messengers are involved in triggering the antiviral effect of interferons alpha and beta. 相似文献
63.
Tobacco cells are sensitive to bleomycin and phleomycin. The Tn5 and the Streptoalloteichus hindustanus (Sh) bleomycin resistance (Ble) genes conferring resistance to these antibiotics have each been inserted into two plant expression vectors. They are flanked by the nopaline synthase (nos) or the cauliflower mosaic virus (CaMV) 35S promoters on one side, and by the nos polyadenylation signal on the other. These four chimaeric genes were introduced into the binary transformation vector pGA 492, which were thereafter mobilized into Agrobacterium tumefaciens strain LBA 4404. The resulting strains were used to transform Nicotiana tabacum cv. Xanthi nc using the leaf disc transformation procedure. In all cases, phleomycin- and bleomycin-resistant tobacco plants were regenerated from transformed cells under selective conditions; however the highest frequency of rooted plants was obtained when transformation was carried out with the Sh Ble gene under the control of the 35S promoter. Phleomycin resistance was stably transmitted to sexual offspring as a dominant nuclear trait as confirmed by Southern blotting. 相似文献
64.
Summary
dl-Malic acid grown cells of Candida sphaerica (anamorph of Kluyveromyces marxianus) formed a saturable transport system that mediated accumulative transport of l(-)malic acid with the following kinetic parameters at pH 5.0: V
max, 0.44 nmol l(-)malate·s-1 per milligram dry weight; K
m
,0.1 mM
l(-)malate. Initial uptake of the acid was accompanied by disappearance of extracellular protons, the rates of which followed Michaelis-Menten kinetics as a function of the acid concentration. Variation with extracellular pH of the K
m
values, calculated either as the concentrations of anions or of undissociated acid, pointed to anions as the transported form. Furthermore, accumulated free acid suffered rapid efflux after the addition of the protonophore carbonylcyanide-M-chlorophenyl-hydrazone (CCCP). These results suggested that the transport system was a dicarboxylate-proton symporter. The system was inducible and was subject to glucose repression. Succinic, fumaric, -ketoglutaric, oxaloacetic and d-malic acid, but not maleic, malonic, oxalic nor l(+)-tartaric acid, apparently used the same transport system since they acted as competitive inhibitors of l(-)malic acid transport and induced proton movements that followed Michaelis-Menten kinetics. Experiments with glucose-repressed cells showed that undissociated dicarboxylic acid (measured with labelled succinic acid) entered the cells slowly by simple diffusion. The permeability of the cells for undissociated acid increased exponentially with pH, the diffusion constant increasing 100-fold between pH 3.5 and 6.0. 相似文献
65.
J R López L E Brice?o G Cordovez V Sánchez N Linares 《General physiology and biophysics》1989,8(2):91-98
Carnitine is required for the transport of activated long chain fatty acids through the mitochondrial inner membrane. We measured the intracellular free calcium concentration [( Ca2+]i) by means of a calcium selective microelectrode in skeletal muscle biopsies obtained from nine patients in which myopathic carnitine deficiency (MCD) was diagnosed, and from six subjects with no evidence of neuromuscular disease. Intact intercostal muscle bundles were dissected and then split for electron microscopic studies and electrophysiological measurements. The [Ca2+]i in muscle fibers from MCD patients was 0.46 +/- 0.02 mumol.l-1 (mean +/- SEM) and 0.10 +/- 0.01 mumol.l-1 in control subjects. At the electron microscopic level, the predominant abnormality was the presence of lipid vacuoles between the myofibrils. These results show that in patients with myopathic carnitine deficiency there is a significant increase in the resting myoplasmic calcium concentration which might be related to a malfunction of some mechanisms responsible for the homeostasis of intracellular calcium. 相似文献
66.
Field Study Comparing Growth and Viability of a Population of Phototrophic Bacteria 总被引:1,自引:0,他引:1 下载免费PDF全文
Carol L. Folt Mary Jo Wevers Michael P. Yoder-Williams Richard P. Howmiller 《Applied microbiology》1989,55(1):78-85
The growth and viability of an anoxygenic, phototrophic bacterial community in the hypolimnion of Zaca Lake, Calif., were compared throughout the summer. The community is dominated by a single species, “Thiopedia rosea,” that inhabits the entire hypolimnion (6 to 8 m) for approximately 11 months. Suboptimal conditions in the hypolimnion (extremely low light intensity, high or low H2S levels) result in zero or extremely low growth rates (doubling times > 1 month) for most of the population, most of the time, yet cells remain viable and capable of high specific growth rates (doubling times of 1 to 10 days) when placed under favorable conditions (higher light intensities and temperatures). We first conclude that phototrophic bacterial populations in situ may frequently exist in a viable yet nongrowing state. Second, the viability of cells is likely to be reduced with depth owing to higher concentrations of potentially toxic chemicals and to changes in the physiological state associated with the prolonged periods of darkness commonly found at the bottom of bacterial plates. 相似文献
67.
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
68.
69.
The pollination biology and breeding systems ofKielmeyera coriacea andK. speciosa, two sympatric woody species common in the cerrado vegetation of C. Brazil, were studied. Both species have similar nectarless, polystemonous Papaver-type flowers which are visited by a similar spectrum of insects, though they bloom in different seasons and are thus phenologically isolated. Large carpenter bees seem to be the most important pollinators and these and other bees effect buzz pollen retrieval despite the fact that anthers are not poricidal. Both species ofKielmeyera possess strong xenogamous breeding systems. The presence of staminate flowers and andromonoecy inK. coriacea, as well as the longevity ofK. speciosa flowers are discussed as alternative strategies to improve pollination success and reproductive efficacy. 相似文献
70.
Mating behavior in seaweed flies (Coelopa frigida) 总被引:1,自引:0,他引:1