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1.
李伟前 《畜禽业》2009,(12):34-37
胰多肽(pancreation polypeptide,PP)是胰脏胰多肽细胞分泌的一种多肽类激素。为了研究胰多肽对肉鸭生产性能和消化机能的影响,实验通过从肉鸭小肠中提取PP粗品,并对其进行纯度鉴定,之后添加到肉鸭体内,产生动物模型,以进行动物实验。具体方案如下:100只肉鸭被随机分为5组,每组20只。Ⅰ组为对照组,每天饲饮自来水。Ⅱ、Ⅲ组分别饲饮剂量为0.58mg/d的PP粗品及剂量为0.29mg/d的PP纯品。Ⅳ、Ⅴ组分别于每周颈部皮下注射0.24mg/只的PP粗品及0.12mg/只PP纯品。饲养称重,宰杀后取小肠,对其进行处理后用紫外吸收法进行消化酶活力测定。结果表明:PP能促进肉鸭机体生长发育,促进体重增长,对肉鸭生产性能产生影响;对肉鸭小肠蛋白酶、淀粉酶和脂肪酶的活力有影响,从而影响消化机能。  相似文献
2.
Earlier studies have established that polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid and docosahexaenoic acid inhibit steroid production in the goldfish testis. As PUFA inhibit testicular steroidogenesis in the rat through activation of protein kinase C (PKC), the present studies were undertaken to characterize the properties of PKC in the goldfish testis and to test the effects of selected PUFA on PKC activity. PKC activity was quantified in goldfish testis homogenate following partial purification by DEAE-cellulose chromatography by determining the transfer of radiolabelled phosphate from [γ - 32P]ATP to histone III-S. Testicular PKC activity was defined by the amount of protein phosphorylation in the presence of phosphatidylserine, phasphatidylcholine, Ca2+ ions and diolein (a 1,2-diacylglycerol analog) above that obtained in response to Ca2+ ions alone. Western blot analysis of a crude testis homogenate using an antibody specific to the α and β isoforms of mammalian PKC led to the identification a single band of protein (80 kD) that co-migrated with PKC from rabbit brain cytosol. Addition of arachidonic, eicosapentaenoic or docosahexaenoic acids failed to activate PKC. However, PKC activity stimulated by phospholipid, Ca2+ ions and diolein was inhibited in a dose related fashion by all of these fatty acids. These studies suggest that the inhibitory effects of EPA and DHA on testicular steroidogenesis are not mediated by activation of PKC. The lack of effect of PUFA on PKC activity in the goldfish testis suggests that either the distribution of PKC isoforms differs between the testis of mammals and fish or that PKC is not activated by PUFA in the goldfish.  相似文献
3.
Intestinal uptake and renal excretion are the primary determinants of inorganic phosphate (Pi) balance in teleosts. In general, teleost kidneys may either reabsorb filtered Pi or secrete excess Pi into the urine. Primary monolayer cultures of flounder (Pleuronectes americanus) renal proximal tubule epithelium (PTCs) have helped identify several hormones that may participate in conservation or excretion of Pi. Mounted in Ussing chambers, the monolayer cultures can be used to assay transepithelial Pi transport. Several factors, including metabolic acidosis, elevation of plasma [Pi], salmon stanniocalcin, salmon somatolactin and mammalian prolactin, have now been shown to alter transepithelial Pi transport in winter flounder PTCs. Salmon stanniocalcin (STC) stimulated Pi luminal-to-peritubular transport (reabsorption) at a dosage of 12.5–50 ng/ml (0.25–1.0 nM). Net Pi transport changed within 30 min and progressively increased from slight net secretion in untreated controls to net reabsorption after 3 h. The target and function of somatolactin have been uncertain. In our hands salmon somatolactin (sSL) also stimulated Pi reabsorption by flounder PTCs in a dose-dependent manner at physiological levels of the hormone (12.5 ng/ml). Net Pi transport was significantly altered by sSL within 2 h after the initial exposure. Neither sSL nor STC had any effect on transepithelial Ca2+ transport. The effects of both sSL and STC were mimicked by forskolin, whereas H-89, a highly specific protein kinase A inhibitor, significantly decreased the effects of the hormones as well as forskolin-induced Pi reabsorption. Furthermore, the production and release of cAMP were increased more than two-fold following exposure to STC or sSL. The data indicate that STC and sSL directly stimulate net renal Pi reabsorption by a cAMP-dependent pathway. In addition, mammalian prolactin greatly, and salmon growth hormone slightly, increased net Pi reabsorptive flux, whereas salmon prolactin had no effect. These results appear to be related to the location of the cysteine disulfide bonds within the molecular structure. Although somatolactin and stanniocalcin may both stimulate renal Pi conservation, their actions may be related to different physiological conditions.  相似文献
4.
The mechanism of modulation of the Na/H antiport was studied in erythrocytes of the tilapia, Oreochromis mossambicus. Activation of the antiport was determined through measurements of variations of intracellular pH, using a pH-sensitive, intracellular fluorescent probe 2′, 7′-bis (carboxyethyl)-5 (6)-carboxyfluorescein (BCECF). Phorbol ester (5 μM), a stimulator of protein kinase C, activated the antiport resulting in an increase of intracellular pH; a maximum of 0.125 ± 0.027 pH units over basal level (mean ± SD; n = 4–6) was reached in 20 min. The effect was blocked by protein kinase C inhibitors staurosporine and H-7, and also by the antiport inhibitor 5-(ethyl-N-isopropyl) amiloride; this demonstrates that the stimulation of the antiport in tilapia erythrocytes can take place through a protein kinase C-mediated mechanism. Vasopressin, an important osmoregulator hormone in teleosts, was able to activate the Na/H antiport, in a manner similar to phorbol ester, but its effect was only partially sensitive to staurosporine inhibition. Considering that the physiological role of the Na/H exchanger in fish is known to be different from its role in mammalian cells, these results indicate that other signal transduction mechanisms can be involved in the modulation of intracellular pH by vasopressin. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献
5.
PKC activity was detected in spleen extracts from the turbot, Scophthalmus maximus, a teleost flatfish that is farmed commercially in several countries, in assays with the substrate EGF- R651–658 as phosphate acceptor. The activity was purified about 700-fold by a three-step chromatographic procedure (DEAE-cellulose, phenyl-Sepharose and threonine-Sepharose). Maximal activity was obtained in the presence of the typical PKC cofactors Ca2+ (0.1 mM) PtdS (20 g ml–1) and either DAG (2 g ml–1) or PMA (2 g ml–1). Activity was dose-dependently inhibited by H7 and by the PKC-specific inhibitors PKC19–36 and N-myristoylated PKC19–31. The rate of phosphorylation was highest with the PKC-specific substrate MARCKS161–175. In immunoblotting, MC5 (a mouse monoclonal antibody raised against bovine PKC) recognized bands of 80 and 100 kDa. Immunoblotting with antibodies raised against mouse PKC isozymes (, , , , , , and ) indicated the presence of all these isozymes in turbot spleen.  相似文献
6.
The direct effect of osmolality on growth and mRNA population were investigated in the rainbow trout cell line (RTG-2). These cells can grow in the media of osmolalities ranging from 200 to 600 mosmol kg-1. With two-dimensional electrophoresis, the in vitro translation of poly(A+) RNA isolated from these cells showed osmoresponsive changes in the population of translatable mRNAs. Using differential mRNA display polymerase chain reaction, however, we identified inducible cDNA products in hyper-osmotic and hypo-osmotic media as third component of complement, and as homologues of known genes: an atypical protein kinase regulated by the thyrotropin-dependent mitogenic pathway, nucleolin and CHD3. The remaining cDNAs have no significant homology in GenBank. Northern blots demonstrate that their mRNA levels were induced in hyper-osmotic and hypo-osmotic media, but not by other stresses. The expressed proteins of these mRNAs may be involved directly or indirectly in the adaptation of RTG-2 cells to different osmolalities probably through the osmotic signal transduction and adjustment in cellular metabolism to osmotic stress.  相似文献
7.
The mechanisms of pituitary adenylate cyclase activating polypeptide (PACAP) action on goldfish growth hormone (GH) release were investigated by examining GH release responses from dispersed goldfish pituitary cells to a synthetic mammalian (m)PACAP38 peptide. It was established that GH release stimulated by 2-h exposure to mPACAP38 was concentration-dependent, attenuated by the PACAP receptor antagonist mPACAP6–38, and subject to neuroendocrine modulation by somatostatin. Maximal mPACAP38-stimulated GH release was not additive to the responses elicited by either the adenylate cyclase activator forskolin or the cyclic (c)AMP analog 8-bromo-cAMP. The GH responses to mPACAP38, forskolin and 8-bromo-cAMP, either alone or in combination, were abolished by H89, a protein kinase A (PKA) inhibitor. SQ22536, an adenylate cyclase inhibitor, attenuated forskolin- and mPACAP38-stimulated GH release. In contrast, mPACAP38-stimulated GH release were additive to the responses to two protein kinase C (PKC) activators and unaffected by two PKC inhibitors. These results suggest that the stimulatory action of PACAP on GH secretion is mediated through a cAMP- / PKA-dependent mechanism, whereas the involvement of PKC appears unlikely. The ability of mPACAP38 to further enhance maximal GnRH (PKC)-dependent GH release, but not dopamine D1 agonist (PKA)-dependent GH secretion, is consistent with this hypothesis. A possible involvement of Ca2+ in PACAP action is also suggested. Two inhibitors of voltage-sensitive Ca2+ channel reduced the GH responses to mPACAP38 in static incubation; conversely, mPACAP38 increased intracellular [Ca2+] in identified, single goldfish somatotropes.  相似文献
8.
9.
蛋白激酶C(PKC)广泛参与哺乳动物T、B淋巴细胞涉及的免疫反应并发挥重要作用,然而PKC在鱼类免疫过程中的作用却少有报道。本研究在半滑舌鳎(Cynoglossus semilaevis)中克隆了PKC家族的典型成员PKCα(命名为CsPKCα),并进行了分子特征和表达模式分析。CsPKCα的cDNA全长为2315 bp,其中,开放阅读框(ORF)为2013 bp。qRT-PCR分析显示,CsPKCα在各个组织中广泛表达,其中,在鳃、肝脏、皮肤和肠中具有较高的转录水平,表明CsPKCα可能在免疫过程中发挥作用。随后检测了CsPKCα在哈维氏弧菌(Vibrio harveyi)感染后6种免疫相关组织(鳃、肝脏、皮肤、肠、脾脏和肾)中不同时间点的表达水平,发现细菌侵染后24 h或48 h,CsPKCα在鳃、肾脏、皮肤和脾脏中显著上调,侵染后12 h在肝中有显著性下调。研究表明,CsPKCα可能在应对哈维氏弧菌的免疫应答中发挥作用,但是否参与病原菌侵染的巨噬细胞激活以及与T、B细胞相关的信号通路还需要进一步研究。这是关于PKCα参与鱼类细菌性免疫反应的首次报道。  相似文献
10.
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