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Nitric oxide synthase (NOS) is an enzyme that catalyzes the formation of nitric oxide (NO), an important biological messenger from L-arginine. There are considerable evidence showing the expression of NOS in mammalian tissues. Information on distribution of NOS activities in various organs and tissues of fish is rare. Non-functional NOS activities were documented in fish semi-quantitatively either by an indirect nicotine-adenine-dinucleotide-phosphate diaphorase (NADPH-d) activity histochemical staining method or by an immunohistochemical method using a cross-reacting antibody to brain NOS. Report on the functional levels of NOS activities in fish is lacking. This report represent the first attempt to document the functional NOS levels in various fish organs and tissues. Constitutive NOS (cNOS) activities in various organs of big-head carp (Aristichthys nobilis) was measured by a chemiluminescence method with a detection limit as low as 10 mol of NO produced. It was found that constitutive NOS activity was highest in the brain, followed by the intestine, stomach, retina, olfactory lobe, swim bladder, skeletal muscle, heart, kidney, ovary and liver. NOS activity could not be detected in the gill filaments. Omission of NADPH in the reaction mixture caused a 57–100% decrease in cNOS activities. However, omission of arginine in the mixture only caused a 56–87% drop in cNOS activities. When compared with cNOS activities documented from other species, a similar pattern of cNOS activities in the various organs and tissues of big-head carp could be seen.  相似文献   
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A phosphatidylinositol-glycan-specific phospholipase D (PI-G PLD) that specifically hydrolyzes the inositol phosphate linkage in proteins anchored by phosphatidylinositol-glycans (PI-Gs) has recently been purified from human and bovine sera. The primary structure of bovine PI-G PLD has now been determined and the functional activity of the enzyme has been studied. Expression of PI-G PLD complementary DNA in COS cells produced a protein that specifically hydrolyzed the inositol phosphate linkage of the PI-G anchor. Cotransfection of PI-G PLD with a PI-G-anchored protein resulted in the secretion of the PI-G-anchored protein. The results suggest that the expression of PI-G PLD may influence the expression and location of PI-G-anchored proteins.  相似文献   
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Genetics aims to understand the relation between genotype and phenotype. However, because complete deletion of most yeast genes ( approximately 80%) has no obvious phenotypic consequence in rich medium, it is difficult to study their functions. To uncover phenotypes for this nonessential fraction of the genome, we performed 1144 chemical genomic assays on the yeast whole-genome heterozygous and homozygous deletion collections and quantified the growth fitness of each deletion strain in the presence of chemical or environmental stress conditions. We found that 97% of gene deletions exhibited a measurable growth phenotype, suggesting that nearly all genes are essential for optimal growth in at least one condition.  相似文献   
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To quantitate acetylpromazine-induced alpha-adrenergic receptor blockade, phenylephrine was infused into dogs. The amount of phenylephrine necessary to increase the mean arterial blood pressure (MAP) 50% above base line, with or without the prior administration of acetylpromazine, served to quantify the degree of acetylpromazine-induced alpha-adrenergic receptor blockade. Seven dogs were anesthetized with thiopental, maintained on halothane in oxygen, and mechanically ventilated. All infusions were made through a catheter in the cephalic vein. Continuous recordings were made of MAP and a lead II ECG. After induction of anesthesia, instrumentation, and stabilization of heart rate, MAP, and ventilation, 6 group I dogs were infused with phenylephrine until a 50% increase in MAP was recorded (phenylephrine control). On subsequent research days, each dog was anesthetized, instrumented as described, and given (IV) 1 of 3 dosages of acetylpromazine in the following order--0.05, 0.125, and 0.25 mg/kg. The dose of phenylephrine necessary to increase MAP 50% in the presence of acetylpromazine was recorded. Five group II dogs were studied as in group I, but each dog was given (IM) atropine (0.04 mg/kg) before anesthetization. Two dosages of acetylpromazine were studied in the following order--0.05 and 0.25 mg/kg. Group I dogs, when compared with their phenylephrine controls, were given significantly more phenylephrine to raise MAP 50% at each dose of acetylpromazine studied. The same trend was observed in group II dogs, but at smaller doses of phenylephrine, probably as a result of the positive chronotropic effect of atropine on the heart.  相似文献   
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Of 345 market chicken carcasses received directly from selected processing plants across Canada, six yielded salmonellae. One of the plants submitted 122 carcasses none of which yielded these organisms. A second plant had one Salmonella-contaminated carcass among 20 which were examined. Each of these two plants was subected to detailed bacteriological examinations on four occasions.

In these detailed examinations a total of 175 samples or specimens for culture were taken from a variety of surfaces including vent areas of carcasses, operators' hands, equipment surfaces and from water in tanks of iced birds. Twenty-five (14 per cent) of the cultures yielded salmonellae and all but one of these were either S. oranienburg or S. infantis. Isolations were made during five of the eight series of examinations. The evidence indicated that Salmonella-infected flocks were frequently slaughtered and that Salmonella contamination could become widespread in the plant during processing. The organisms are apparently eliminated from all but a small percentage of the carcasses during processing but opportunities exist for recontamination during subsequent handling.

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The mammalian intestinal tract is colonized by trillions of beneficial commensal bacteria that are anatomically restricted to specific niches. However, the mechanisms that regulate anatomical containment remain unclear. Here, we show that interleukin-22 (IL-22)-producing innate lymphoid cells (ILCs) are present in intestinal tissues of healthy mammals. Depletion of ILCs resulted in peripheral dissemination of commensal bacteria and systemic inflammation, which was prevented by administration of IL-22. Disseminating bacteria were identified as Alcaligenes species originating from host lymphoid tissues. Alcaligenes was sufficient to promote systemic inflammation after ILC depletion in mice, and Alcaligenes-specific systemic immune responses were associated with Crohn's disease and progressive hepatitis C virus infection in patients. Collectively, these data indicate that ILCs regulate selective containment of lymphoid-resident bacteria to prevent systemic inflammation associated with chronic diseases.  相似文献   
9.
盐分处理对3种杨树离子吸收规律的影响   总被引:5,自引:0,他引:5  
对意大利杨,群众杨和胡杨分别进行了盐分处理,处理后的第1周发现不同处理对钠Na^+和Cl^-的吸收有显著的影响,意大利杨和群众杨对盐分离子的吸收随盐分处理浓度的升高而升高,而胡杨却不是这样,相对其它两种杨树而言,胡杨较低的盐分吸收很可能是由于其离子选择能力较高所造成的。  相似文献   
10.
A polysaccharide (GSP-6B) with a molecular mass of 1.86 × 10? Da was isolated from the fruiting bodies of Ganoderma sinense . Chemical composition analysis, methylation analysis, infrared spectroscopy, and nuclear magnetic resonance spectroscopy were conducted to elucidate its structure. GSP-6B contains a backbone of (1→6)-linked-β-D-glucopyranosyl residues, bearing branches at the O-3 position of every two sugar residues along the backbone. The side chains contain (1→4)-linked-β-D-glucopyranosyl residues, (1→3)-linked-β-D-glucopyranosyl residues, and nonreducing end β-D-glucopyranosyl residues. An in vitro immunomodulating activity assay revealed that GSP-6B could significantly induce the release of IL-1β and TNF-α in human peripheral blood mononuclear cell (PBMC) and showed no toxicity to either PBMC or a human macrophage cell line THP-1. GSP-6B could also activate dendritic cells (DC) by stimulating the secretion of IL-12 and IL-10 from DC.  相似文献   
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