Constant Light Exposure Causes Dissociation in Gonadotrophin Secretion and Inhibits Partially Neuroendocrine Differentiation of Leydig Cells in Adult Rats     

HH Ortega  JA Lorente  GA Mira  C Baravalle  NR Salvetti 《Reproduction in domestic animals》2004,39(6):417-423

The objective of this work was to study the changes that occur in the Leydig cells of rats exposed to continuous light. The laboratory rat is considered a non-photoperiodic species because exposure to short photoperiod has little or no effect on the reproductive status. However, exposure of adult female rats to constant light induces polycystic ovaries, indicating that extreme changes in the photoperiod affect the reproductive function seriously. Adult male rats were placed under continuous light conditions for a duration of 15 weeks. After this period, the animals were killed and testicles were dissected and processed by routine histologic protocols. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) serum levels were determined by radioimmunoassay (RIA). The visualization of antigens was achieved by the streptavidin-peroxidase immunohistochemical method. Antibodies against chromogranin A, S-100 protein, P substance, synaptofisin, neurofilament protein-200, gliofibrillary acidic protein and neurone-specific enolase were used. The mean LH serum concentration was significantly lower, while the mean FSH level was significantly higher in treated animals. The expression of S-100, NSE, CrA, SP and SYN was significantly lower in treated animals. In conclusion, the constant light exposure acting directly at the pituitary level decreases LH secretion. The increased FSH secretion may be due to a partial reduction of the negative androgen feedback in the pituitary gland. Moreover, the constant light exposure affects the expression of some immunomarkers in Leydig cells, possibly because of the changes found in the gonadotrophin level and feedback mechanism.  相似文献   

玉米的不同温度和时间烘烤加工处理对泌乳奶牛瘤胃干物质和淀粉降解规律的研究     

齐智利  嗄尔迪  陈慧君  赵芙蓉  尹福泉  刘瑞芳 《畜牧兽医学报》2006,37(7):667-671

以3头安装永久性瘤胃瘘管的泌乳前期荷斯坦奶牛为试验动物，在精粗比为55：45的日粮条件下，采用In sacco法测定了不同温度和时间烘烤加工处理的玉米在奶牛瘤胃内干物质和淀粉的降解规律。结果表明，玉米经过不同温度和时间的烘烤处理，干物质和淀粉的瘤胃降解率都有不同程度的降低，随着温度逐渐升高、作用时间逐渐延长，干物质和淀粉的降解率也逐渐降低。在所有处理组中，140℃35min处理组可以明显降低玉米的瘤胃淀粉降解率（P〈O．05），比未处理玉米组降低了15．26％。淀粉在瘤胃中降解的影响因素最主要的是淀粉的快速可溶部分和降解速率。  相似文献   

Influence of Heat Stress on the Cortisol and Oxidant‐Antioxidants Balance During Oestrous Phase in Buffalo‐Cows (Bubalus bubalis): Thermo‐protective Role of Antioxidant Treatment     

GA Megahed  MM Anwar  SI Wasfy  ME Hammadeh 《Reproduction in domestic animals》2008,43(6):672-677

In the present study, the effect of heat stress, which is commonly observed in the animals of Upper Egypt area in summer, as well as the effect of antioxidant treatment as a thermo‐protective was examined. In this study, the animals (n = 120) were divided into winter group (n = 40, bred during winter) and summer group (n = 80, bred during summer) as well as, animals in the summer group were divided into first subgroup animals (n = 40) and injected with Viteselen intramuscularly (15 ml) twice weekly for 10 weeks and second subgroup animals (n = 40) were not treated (as control). Serum levels of progesterone (P4), oestradiol (E2), cortisol, superoxide dismutase (SOD), lipid peroxidase (LPO) and nitric oxide (NO) were measured. The pregnancy rate of all animals was detected rectally. The levels of oestradiol and the activity of the antioxidant SOD were decreased in serum of animals in behavioural oestrus during summer as compared with those in winter. During the same time period the levels of oxidants such as LPO and NO were increased in the serum of animals again in the phase of oestrus. In another group of animals treated by intramuscular injection with 15 ml viteselen (antioxidant) twice weekly for 6 weeks during hot months, the activities of serum SOD showed an increase and the levels of oxidants and cortisol decreased. Moreover, the levels of oestradiol were increased during the oestrous behaviour. The pregnancy rate was decreased in animals under heat stress and the pregnancy rate was enhanced dramatically when these animals received antioxidants during the heat stress. This means that the heat‐stress in Upper Egypt may affect the fertility of animals and pregnancy rate and this effect may be through an increased production of free radicals and decreased production of antioxidants as well as increased levels of cortisol. Treatment of animals or supplementation with antioxidants before the beginning of months of heat‐stress and also during the stress period may correct the infertility due to heat‐stress through the decrease in cortisol secretion and a decrease in the oxidative stress. These results resulted in an increase in pregnancy rate in treated animals.  相似文献   

益生菌Lactobacillus casei|Zhang 高密度发酵中试工艺及动力学研究   总被引：1，自引：0，他引：1  

李妍  高鹏飞  赵文静  麻士卫  周琦  潘向辉  张和平 《中国农业科技导报》2008,10(5):59-65

在益生菌L.caseiZhang高密度培养小试（3L）基础上,进行30L到150L逐级放大中试生产工艺的研究以确定规模化生产工艺。在优化的发酵工艺下,150L规模发酵菌体密度可达2.9×10^10cfu/mL,与小试水平无差异。采用origin7.5软件在logistic equation基础上建立L.caseiZhang的生长和葡萄糖代谢动力学模型,模型与试验值拟合良好,平均误差小于10%,能够较好地反应发酵过程。初步探讨发酵后菌体的离心和冷冻干燥过程对菌体的影响,虽然发酵液经离心收集菌体后冷冻干燥可得到平均活菌数2.65×10^11cfu/g的菌粉,能够满足益生菌制剂和发酵剂对高活菌数的要求,但冻干前后活菌得率仅49.97%。有必要针对L.casei Zhang的冻干保护剂和冻干工艺进一步优化,以提高菌体存活率得到更高菌体浓度的益生菌粉。  相似文献   

SCN-AVP release of <Emphasis Type="Italic">mPer1/mPer2</Emphasis> double-mutant mice in vitro     

Daan R van der Veen  Ellis GA Mulder  Henrik Oster  Menno P Gerkema  Roelof A Hut 《Journal of circadian rhythms》2008,6(1):5

  相似文献   

阿克苏引种面包小麦济南17号超高产栽培初探     

张卫东  秦勇  赛买提  古拉音  张巨松 《新疆农业科学》2005,42(Z1):22-24

阿克苏地区2000-2001年从山东省农科院引进强筋面包小麦新品种济南17号,在地区农业试验站进行品种区域适应性比较试验,并对其生育和植株性状进行了观测,在参试的8个品种中,济南17号平均产量6804kg/hm2,位居第三,较对照邯5316(地区小麦主栽品种)增产840kg/hm2,增产率14%。2001-2002年又在地区农业试验站对该品种示范种植800.04m2,产量8550kg/hm2,首次实现本地区引种面包小麦单产超8250kg/hm2的产量水平,两年试验示范结果表明,该品种在阿克苏地区具有较强的适应性和丰产性,同时取得了实现强筋小麦济南17号高产栽培的实践经验。  相似文献   

Efficacy of a novel copper-based footbath preparation for the treatment of ovine footrot during the spread period     

GA REED  DU ALLEY 《Australian veterinary journal》1996,74(5):375-382

Objective: To determine the efficacy of a novel copper based footbath preparation (CHF-1020) for treatment of ovine footrot during the spread period.
Design: A series of field trials with treated and control groups run together.
Animals: Mobs of at least 125 sheep on each of six properties in southern New South Wales with equal numbers of controls.
Procedure: Sheep of group A were treated after minimal paring by making them stand in CHF-1020 for 15 minutes. Treatment was undertaken at intervals throughout the period of the trials (14 September to 17 December 1993). Group A sheep were run on the same pasture as those from group B (untreated sheep).
Results: The percentage of sheep exhibiting clinical signs of ovine footrot at the start of the trial ranged from 35 to 88% at score 3 or higher, using a 0 to 5 footscoring system. During the trial, the percentage of infected sheep (greater or equal to score 2) in group B increased and ranged from 40 to 90%. The level of infected sheep in group A on each property was reduced progressively to 1 to 16%. Cure rates of 45 to 94% were achieved, with the lowest rate being on a property with a metal footbath. The next lowest cure rate was 73%. Results indicated that treatment should be undertaken at 2-weekly intervals while spread continues. Treated sheep can be returned to contaminated pastures.
Conclusion: CHF-1020 is effective during the spread period and can be used for the progressive eradication of ovine footrot.  相似文献   

论琵琶演奏音乐语言表现力的多元性     

高微 《湖南农业大学学报(自然科学版)》2009,(2)

从音乐本身出发,从琵琶音乐语言和琵琶音乐表达的技术手段两方面对琵琶音乐语言的表现力作出作者自身的理解.琵琶音乐语言的表现力是多元性的,可以从琵琶音乐语言特性的界定以及琵琶音乐表达的技术手段来了解.  相似文献   

H_2O_2对离体小麦叶片中蛋白质含量下降的影响     

高玲  郝言芹  孙晓红  牟其云 《江西农业学报》2007,19(2):17-18

H2O2能氧化修饰离体小麦叶片蛋白质分子中的-SH基团,使蛋白质分子更容易被蛋白水解酶降解,表现为蛋白水解酶活力升高,蛋白质含量下降加快。随着H2O2浓度的增大,这一现象更加明显。  相似文献   

The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria     

DJ HARRIS  CD HIBBURT†  GA ANDERSON‡  PJ YOUNIS†  DH FITSPATRICK§  AC DUNN¶  IW PARSONS  NR McBEATH 《Australian veterinary journal》1988,65(6):171-176

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.  相似文献