Chicken leptin: properties and actions

Chicken leptin cDNA shows a high homology to mammalian homologous, with an expression localized in the liver and adipose tissue. It is noteworthy, that the hepatic expression is most likely associated with the primary role that this organ plays in lipogenic activity in avian species. As in mammals, chicken leptin expression is regulated by hormonal and nutritional status. This regulation is tissue-specific and with a high sensitivity in the liver compared to adipose tissue. The blood leptin levels are regulated by the nutritional state with high levels in the fed state compared to the fasted state. The recombinant chicken leptin markedly inhibits food intake as reported in mammals, suggesting the presence of an hypothalamic leptin receptor. The chicken leptin receptor has been identified and all functional motifs are highly conserved compared to mammalian homologous. Chicken leptin receptor is expressed in the hypothalamus but also in other tissues such as pancreas, where leptin inhibits insulin secretion and thus may have a key role in regulating nutrient utilization in this species.     

环丙沙星对水产动物气单胞菌的药效学研究

环丙沙星为第三代步诺酮类药,是一种安全。高效的抗菌剂。该药对临床分离的几株致病性气单胞菌的最小抑制浓度（MIC）为0.0098μg/ml。人工感染治疗试验表明,该药以1mg/（kg.d）剂量灌服,连用5天,能有效控制鲫鱼败血症的暴发。     

日本结缕草ZjNAC1的克隆、转录激活活性、亚细胞定位及表达分析

采用RACE技术从日本结缕草中克隆得到ZjNAC1转录因子(GenBank No. MH428376),其开放阅读框为945bp,编码314个氨基酸。ZjNAC1编码的蛋白在N端有1个典型的NAM保守结构域,属于NAC转录因子家族。通过染色体步移的方法,获得ZjNAC1基因ATG上游1635bp序列,分析发现其包含响应脱落酸(ABA)、茉莉酸甲酯(MeJA)及逆境胁迫的作用元件。构建pGBKT7-ZjNAC1载体,转化Y2HGold酵母感受态细胞,发现ZjNAC1具有转录激活活性。农杆菌介导的35S-ZjNAC1-YFP载体注射本生烟草叶片瞬时表达结果显示,ZjNAC1定位于细胞核。实时荧光定量结果表明,ZjNAC1在日本结缕草根中表达量最高;此外,ZjNAC1的表达受10μmol/L MeJA和20%PEG4000处理的诱导,但受200μmol/L乙烯(ET)、10μmol/L ABA和300mmol/L NaCl处理的抑制。     

双峰驼精清诱导排卵活性成分的DEAE—纤维素柱层析分离及其生物活性

选用DEAE－纤维素离子交换柱对双峰驼精清进行分离，各层析组分用于大鼠垂体组织体外培养，并给母驼肌注有活性的组分，以RIA法测定垂体组织培养液和母驼血浆中LH及FSH的浓度。结果表明，驼精清经DEAE－纤维素柱分离后可得到5个蛋白组分（L1－L5），其中L3在大鼠垂体培养时引起LH释放明显增加（P＜0．05），FSH则无明显变化。给卵巢上无大卵泡发育的母驼肌注有活性的组分L3，可引起血浆中LH明显升高，FSH也无变化。由此表明，L3在体内外试验中均具有引起LH释放的生物活性，它可能是诱导排卵的活性因子或其成分之一。     

土壤脲酶活性两种测定方法的比较

利用比色法和扩散法对金强河地区和甘肃农业大学校园内的土壤脲酶活性进行了分析。结果表明：比色法和扩散法测定的土壤脲酶活性平均值分别为（0．531±0．207）mg／g和（0．446±0．204）mg／g,两种测定方法的结果和变异系数差异均不显著（P〉0．05）。但从试验操作方面考虑,扩散法操作比较简单、所用药品种类少、时间短,是一种比较可行的土壤脲酶活性测定方法。     

利血平增敏法检测恩诺沙星药物残留的研究

目的了解恩诺沙星对金黄色葡萄球菌(金葡菌)的抗菌活性及利血平对其抗菌活性的影响。方法采用对倍稀释浓度琼脂平板法测定抗菌药物的最低抑菌浓度(MIC)值,同法测定利血平对恩诺沙星对金葡菌MIC值的影响。结果利血平可有效增强恩诺沙星的抗菌活性,增大了恩诺沙星抑制金葡菌的抑菌圈直径,提高了恩诺沙星在组织中检测的灵敏度。研究发现利血平加入后中心浓度由0.5ul/ml变为0.0625ul/ml,最低检测限由0.125μg/ml降低到0.015625μg/ml。最低检测限减低了8倍。     

Specific and non‐specific immunity of piglets from sows fed diets containing specific fatty acids in field conditions

The transfer of passive immunity from sows to piglets is important and it is the first immune protection of the new born piglet. Improving sows immunity by adding immuno‐stimulating product in sows diet can positively affect colostrum composition and transfer of immune molecules to piglets. The aim of the current study is to evaluate the benefit of a different solution, made of specific fatty acids from marine origin that have been used in human medicine for decades, for sows and piglets. Two trials were conducted in commercial farm, involving 240 sows at different periods of the year. Sows were divided in a control group, without supplementation, and a test group, supplemented with the feed additive from the 90th day of gestation to weaning. Sows body condition, piglets viability and growth were recorded. Milk immunoglobulin content was measured, as well as Aujeszky antibodies in sows and piglets blood as marker of specific immunity, and blood bactericidal activity, complement activity and lysozyme as markers of non specific immunity. No effect of the product was observed on piglets zootechnical criteria and specific immunity parameters but significant improvement of piglet non specific immunity, was observed. No difference was observed neither in the piglets blood PRRSV and PCV2 antibodies and viruses nor in Aujeszky antibodies. Blood complement activity seems to be an accurate indicator of immuno‐stimulating additive efficiency. Giving alkyl‐glycerol fatty acids to sows in late gestation and lactation can improve the passive immunity transfer to piglets.     

有效纤维及其在奶牛日粮中的应用

奶牛日粮纤维的化学与物理特性对于刺激其咀嚼活动和维持稳定的乳脂率十分重要。奶牛对日粮中有效中性洗涤纤维（eNDF）水平的反应是乳脂率变化，而对日粮物理有效中性洗涤纤维（peNDF）水平的反应是其咀嚼活动。目前产奶牛peNDF最低推荐量是占日粮干物质的21％。本文对奶牛日粮有效纤维的发展、eNDF和peNDF的概念、奶牛对日粮有效纤维的反应、日粮peNDF的估测方法以及奶牛对peNDF的最低需要量进行了简单的综述。     

谷氨酰胺对早期断奶仔猪胰腺及小肠胰蛋白酶活性的影响

选用大长北母猪所产仔猪 45头 ,2 1日龄断奶。断奶时宰杀 5头公仔猪作为哺乳对照 ,其余仔猪按公母各半随机分为 2组 ,试验组添加 1.2 %谷氨酰胺。断奶后 14d和 2 8d宰杀仔猪 ,以研究谷氨酰胺对早期断奶仔猪胰腺和小肠胰蛋白酶活性的影响。断奶后 14d,日粮中添加谷氨酰胺可极显著提高胰腺胰蛋白酶相对活性和总活性 (P<0 .0 0 1)以及比活 (P<0 .0 1) ,而对十二指肠、空肠和回肠食糜及粘膜中胰蛋白酶活性无显著影响 ;断奶后 2 8d时 ,日粮添加谷氨酰胺对胰腺、十二指肠、空肠和回肠食糜粘膜中胰蛋白酶活性均无显著影响。对照组仔猪胰腺、十二指肠和回肠胰蛋白酶活性在断奶后 14d已基本恢复到断奶时水平 ,空肠胰蛋白酶活性显著超过断奶时水平 (P<0 .0 5 ) ;断奶后 2 8d胰腺胰蛋白酶比活和总活性极显著高于断奶后 14d(P<0 .0 1) ,胰腺和回肠胰蛋白酶相对活性显著高于断奶后 14d(P<0 .0 5 )。试验组仔猪胰腺和空肠胰蛋白酶相对活性和比活在断奶后 14d极显著超过断奶时水平 (P<0 .0 1) ,达到了对照组断奶后 2 8d时酶活性水平 ;断奶后 2 8d胰腺胰蛋白酶相对活性、比活和总活性维持在断奶后 14d水平 ,而空肠胰蛋白酶相对活性和比活又降至断奶时水平。结果表明 ,早期断奶仔猪日粮中添加谷氨酰胺有助于缓解由于早期