头孢喹诺对几种常见动物病原菌的体外抗菌作用

采用微量肉汤稀释法测定国产头孢喹诺对5种常见动物病原菌的最小抑菌浓度(MIC),并与头孢噻呋、氨苄西林及环丙沙星进行比较。结果显示头孢喹诺对金黄色葡萄球菌的MIC为1~2μg/mL,抗菌活性强于其他3种药物;对大肠杆菌的MIC≤0.031~0.25μg/mL,抗菌活性与环丙沙星相近,高于头孢噻呋和氨苄西林;对链球菌的MIC≤0.031~1μg/mL,抗菌活性与头孢噻呋和氨苄西林相近,高于环丙沙星;对多杀性巴氏杆菌以及胸膜肺炎放线杆菌的MIC分别≤0.031~0.5μg/mL和≤0.031μg/mL,抗菌活性与头孢噻呋和环丙沙星相近,强于氨苄西林。结果表明头孢喹诺对革兰氏阳性和阴性菌均具有强大的体外抗菌作用。     

模拟增温与施肥对高寒草甸土壤酶活性的影响

摘要：采用开顶式生长室模拟增温的方法,研究了气温升高和施肥对高寒草甸土壤酶活性的影响。研究表明,单独增温导致高寒草甸土壤纤维素酶和磷酸酶活性分别提高了12.4%、29.1%,而脲酶活性降低了18.0%,过氧化物酶和多酚氧化酶活性无明显变化,说明增温促进高寒草甸土壤中碳磷循环。在不增温条件下,施肥抑制了土壤纤维素酶、多酚氧化酶和过氧化物酶活性,而施NPK则提高了脲酶和磷酸酶活性。增温条件下,施肥不会引起土壤纤维素酶、多酚氧化酶和过氧化物酶活性的显著变化,而施可溶性碳肥使脲酶活性显著升高（P<0.05）,施NPK使磷酸酶活性显著降低。增温和施肥的交互作用对土壤纤维素酶、过氧化物酶、磷酸酶和脲酶活性有显著影响,而对多酚氧化酶无明显影响。因此,预测在未来气候变暖背景下,高寒草甸土壤中的多种酶活性对施肥的响应可能不显著。     

柞蚕蛹血淋巴多酚氧化酶活性影响因素的研究

柞蚕血淋巴中多酚氧化酶活性的大小对柞蚕丝产量有一定影响,并对柞蚕蛹色起着非常重要的作用。本试验采用分光光度计法对柞蚕蛹血淋巴多酚氧化酶活性大小的影响因素进行了研究。结果表明:柞蚕蛹血淋巴多酚氧化酶的最适pH值为5.0;最适温度为25℃;少量的苯基硫脲对其的抑制作用较为明显;不同化合物对多酚氧化酶的活性影响不同,在相同浓度下,氯化钙和氯化镁对柞蚕蛹血淋巴多酚氧化酶的活性有促进作用,其他化合物(EDTA,维生素C和亚硫酸钠等)则表现为抑制作用。     

盐胁迫对菘蓝幼苗生长和抗性生理的影响

以“定蓝1号”为试验材料,采用不同浓度NaCl溶液(0,30,60,90,120和150 mmol·L^-1)对菘蓝幼苗进行处理,胁迫14 d后测定了其生长指标、生物量积累、叶片相对含水量、根系活力、根质膜透性、渗透调节物质含量以及抗氧化酶活性等指标,分析不同程度盐胁迫对菘蓝幼苗生长和抗性生理的影响。结果表明:NaCl胁迫对菘蓝幼苗株高和根长都有抑制作用,对根和叶的物质积累也有显著影响,并随浓度的递增呈降低的趋势;菘蓝幼苗叶片相对含水量和根系活力均随NaCl浓度的增加呈现下降趋势,而根质膜透性、叶片脯氨酸含量则呈升高趋势;丙二醛(MDA)含量、组织自动氧化速率(RAD)、过氧化物酶(POD)活性和超氧化物歧化酶(SOD)活性都随NaCl浓度的增加呈先升高后降低的趋势。但当NaCl浓度低于90 mmol·L^-1时,菘蓝幼苗的生长没有受到盐胁迫的明显抑制,根系活力降低不明显,脯氨酸、丙二醛含量和保护酶活性也未显著升高,说明菘蓝幼苗对低浓度盐环境具有一定的耐受性。     

家蚕血液、消化液中酸性核糖核酸酶和天冬酰胺酶活性的初步研究

测定了家蚕夏芳、长灰A和大造各品种血液、消化液中酸性核糖核酸酶及家蚕秋白、夏芳、长灰A和大造各品种天冬酰胺酶性变化。结果表明：各品种血液、消化液中酸性核糖核酸酶、天冬酰胺酶活性变化随发育呈现较强的规律性，血液中，4龄第3d、5龄第3d这两种酶均出现峰值，4龄眠前活性较低，消化液中，5龄第3d这两种酶活性均较高，不同品种这两种酶活性峰值出现时间有差异；各品种血液中酸性核糖核酸酶、天冬酰胺酶性均明显高于相应品种消化液中这两种酶活性；各品种之间血液、消化液中这两种酶活性有明显差异。     

Effect of short‐term supplementation with rumen‐protected fat during the late luteal phase on reproduction and metabolism of ewes

This study was designed to study the effect of short‐term supplementation with rumen‐protected fat during the late luteal phase on reproduction and metabolism of sheep during breeding season. Seventy‐six ewes (Rahmani, Barki and Awassi × Barki) were allocated to two groups considering genotype: the control ewes (C‐group) received a maintenance diet, and the fat‐supplemented ewes (F‐group) received the maintenance diet plus 50 g/head/day of rumen‐ protected fat (Megalac) for 9 days during which oestrus was synchronized. The latter had been accomplished using double intramuscular injection of prostaglandin F_2α (PGF_2α) 11 days apart. Ovarian activity, serum concentration of cholesterol, glucose, insulin and reproductive performance variables were recorded. Data were analysed considering treatment (group) and genotype. Supplementation had positive effects on the overall mean serum concentrations of cholesterol (p < 0.05), glucose (p < 0.05) on day 6 of nutritional treatment and insulin (p = 0.07) on day 8. Fat supplementation did not affect the total number of follicles, follicle populations and ovulation rate. However, fat‐supplemented Rahmani ewes tended to have higher ovulation rate compared with other breeds (treatment × breed interaction, p = 0.06). Treatment also did not affect the mean concentration of serum estradiol or progesterone. Supplemented ewes had higher conception (p = 0.06) and lambing rates (p < 0.05) compared with control. In conclusion, short‐term supplementation with rumen‐protected fat as a source of energy around breeding time improved metabolism, conception and lambing rates of ewes without effects on steroidogenic capacity and ovarian activity being apparent.     

Uterine Activity after Induction of Hypocalcaemia in the Ovariectomized Camel (Camelus Dromedarius)

Al-Eknah, M.M., Homeida, A.M., Dafalla, E.A., Galil, A.K.A. and Al-Tahir, A.Y., 1997. Uterine activity after induction of hypocalcaemia in the ovariectomized camel (Camelus dromedarius). Veterinary Research Communications, 21 (1), 45-50.Bilateral ovariectomy was performed in three parous, non-pregnant camels. Intrauterine and intra-abdominal pressure changes were recorded using balloon-tipped catheters. Uterine contractions were induced and maintained in the ovariectomized camels by daily intramuscular injections of 5 mg oestradiol benzoate throughout the experimental period. The frequency of uterine contractions varied from 6 to 9 per minute, whereas the amplitude varied from 2 to 3 kPa in all the animals. Inducing hypocalcaemia to a level of 0.5 mmol/L by Na2EDTA reduced the amplitude of the contractions to below 1 kPa (p<0.001). The frequency of the contractions was not affected.     

不同桑树品种在土壤水分胁迫下膜伤害和保护酶活性变化

以北方蚕区现行主要桑树品种选792、沙2、新一之舽、陕305、湖桑32号、农桑14号的1年生绿枝扦插苗为实验材料,研究了水分胁迫对不同桑树品种的膜伤害和保护酶活性的影响。在水分胁迫下,细胞膜受到伤害,细胞膜透性增加,电导率随之增强,作为膜脂过氧化产物的丙二醛(MDA)含量增加,各品种细胞膜受到的伤害度有差异。保护酶SOD、POD、CAT活性都表现出先升后降的变化趋势,但变化规律又有所不同。推测各品种抗旱性存在较大差异,6个供试桑品种抗旱能力从大到小依次为选792>陕305>农桑14号>湖桑32号>新一之舽>沙2。