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1.
Eight- to ten-year old French hybrid Vidal 256 grapevines in southern Maryland produced berries about one-third normal size but did not express any obvious leaf symptoms. Electron microscopy of negatively stained tissue-dip preparations and sectioned material from such vines showed individual and membrane-associated 28 nm spherical virus-like particles and closteroviruslike particles. The spherical particles were characterized as an isolate of tomato ringspot virus (TomRSV-G) that infected a wide range of herbaceous hosts by mechanical inoculation, but did not infect tomato, bean or petunia plants susceptible to the type strain of TomRSV. The closterovirus-like particles did not react, by immunosorbent electron microscopy, with antisera to grapevine virus A (grapevine stem-pitting associated virus of Conti et al. 1980) or the 2200 nm Swiss grapevine leafroll closterovirus (Gugleri et al. 1984). 相似文献
2.
Both 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and carbon tetrachloride (CCl4) have conspicuous effects on lipid metabolism in rat liver. Although it is generally accepted that CCl4 administration leads to hepatic lipid peroxidation in vivo, conflicting reports from different laboratories make it unclear whether or not lipid peroxidation is involved in the mechanism of toxicity of TCDD. The present study involved pretreating F344 rats with CCl4 or TCDD, then at predetermined times thereafter, giving [U-14C]linoleic acid. A variety of compound classes were monitored in extracts of liver taken 30 min after the label was given. A previously unreported effect of CCl4 was a conspicuous increase in turnover of 1,2-diglycerides. That CCl4 did cause lipid peroxidation was evident from the presence of allylic hydroxyacids not seen in vehicle-treated controls, greatly increased radioactivity in protein-bound material, and decreased levels of arachidonate without decreased synthesis from linolate. Where effects of TCDD pretreatment could be seen, they were much less than the corresponding effects of CCl4. No allylic hydroxyacids were detected in livers of TCDD-treated rats. The concentration of arachidonate was not reduced, and elongation of linolate was not stimulated, indicating that TCDD did not cause extensive-but-repaired peroxidation. It is concluded that while TCDD may slightly increase hepatic lipid peroxidation in rats in vivo, the extent of such stimulation appears to be too slight to account for the toxicity of TCDD. 相似文献
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The chromogenic substrate o-nitrophenyl-beta-d-galactopyranoside (ONPG) was hydrolyzed by lactose-positive Neisseria. Eight strains of pharyngeal origin were examined. In culture reactions, seven strains resembled Neisseria meningitidis with the exception that they produced acid from 1% (w/v) lactose. An eighth strain (V8) differed in that it did not form acid from maltose or from 1% lactose. However, acid formation was observed in 10% lactose cultures of strain V8, suggesting that entry of lactose occurred by passive diffusion, rather than as a result of permease activity. The enzymes which hydrolyzed ONPG were produced constitutively by the cells of all eight strains. Thus, specific activity in these strains was not increased by prior exposure to lactose, or to two other possible inducers, isopropyl-beta-d-thiogalactoside or methyl-beta-d-thiogalactoside. Study of cell-free extracts of one strain showed that the enzyme was heat-labile, having a half-life of 10 min at 45 C. The enzyme was unstable at low protein concentrations, but it was protected completely or partially when albumin or manganous ions were added. The enzyme appeared to be a typical beta-galactosidase: alpha-galactosides (melibiose and p-nitrophenyl-alpha-d-galactopyranoside) were not hydrolyzed, activity against ONPG was not dependent upon inorganic phosphate, and galactose was released by cleavage of ONPG. ONPG hydrolysis provided a simple and rapid method for detecting lactose-positive Neisseria. 相似文献
5.
Summary Two different3H-saxitoxin-binding proteins, with distinct biochemical and functional properties, were isolated from rat brain using a combination of anion exchange and lectin affinity chromatography as well as high resolution size exclusion and anion exchange HPLC. The alpha subunits of the binding proteins had different apparent molecular weights on SDS-PAGE (Type A: 235,000; Type B: 260,000). When reconstituted into planar lipid bilayers, the two saxitoxin-binding proteins formed sodium channels with different apparent single-channel conductances in the presence of batrachotoxin (Type A: 22 pS; Type B: 12 pS) and veratridine (Type A: 9 pS; Type B: 5 pS). The subtypes were further distinguished by scorpion (Leiurus quinquestriatus) venom which had different effects on single-channel conductance and gating of veratridine-activated Type A and Type B channels. Scorpion venom caused a 19% increase in single-channel conductance of Type A channels and a 35-mV hyperpolarizing shift in activation. Scropion venom double the single-channel conductance of Type B channels and shifted activation by at least 85 mV. 相似文献
6.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
7.
Control of band 3 lateral and rotational mobility by band 4.2 in intact erythrocytes: release of band 3 oligomers from low-affinity binding sites. 总被引:5,自引:0,他引:5
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D E Golan J D Corbett C Korsgren H S Thatte S Hayette Y Yawata C M Cohen 《Biophysical journal》1996,70(3):1534-1542
Band 4.2 is a human erythrocyte membrane protein of incompletely characterized structure and function. Erythrocytes deficient in band 4.2 protein were used to examine the functional role of band 4.2 in intact erythrocyte membranes. Both the lateral and the rotational mobilities of band 3 were increased in band 4.2-deficient erythrocytes compared to control cells. In contrast, the lateral mobility of neither glycophorins nor a fluorescent phospholipid analog was altered in band 4.2-deficient cells. Compared to controls, band 4.2-deficient erythrocytes manifested a decreased ratio of band 3 to spectrin, and band 4.2-deficient membrane skeletons had decreased extractability of band 3 under low-salt conditions. Normal band 4.2 was found to bind to spectrin in solution and to promote the binding of spectrin to ankyrin-stripped inside-out vesicles. We conclude that band 4.2 provides low-affinity binding sites for both band 3 oligomers and spectrin dimers on the human erythrocyte membrane. Band 4.2 may serve as an accessory linking protein between the membrane skeleton and the overlying lipid bilayer. 相似文献
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Abstract: Ischemia-induced changes in 31 P NMR relaxation were examined in 16 piglets. NMR spectra were acquired under control conditions and during complete cerebral ischemia induced via cardiac arrest. Changes in T 1 were assessed directly in six animals during control conditions and after 30–45 min of complete ischemia when changes in brain P1 levels had reached a plateau. The T 1 for P1 did not change, i.e., 2.3 ± 0.5 s during control conditions versus 2.4 ± 1.0 s during ischemia. To evaluate phosphocreatine and ATP, two types of spectra, with a long (25-s) or short (1-s) interpulse delay time, were collected during the first 10 min of ischemia (n = 10). Both types of spectra showed the same time course of changes in phosphocreatine and ATP levels, implying that the T 1 relaxation times do not change during ischemia. There were no changes in the linewidths of phosphocreatine, ATP, or P1 during ischemia, implying that the T *2 values remain constant. Our results suggest that the 31 P T 1 and T *2 for phosphocreatine, Pi , and ATP do not change during ischemia, and therefore changes in 31 P NMR peak intensity accurately reflect changes in metabolite concentrations. 相似文献
10.
Hrushikesh S. Chaudhari Omkar S. Palkar KM Abha Mishra Kalyan K. Sethi 《Journal of biochemical and molecular toxicology》2023,37(9):e23417
During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis. 相似文献