Comparison of the ability of the three endogenous GnRHs to stimulate release of follicle-stimulating hormone and luteinizing hormone in chickens

It is well established that GnRH can stimulate the release of LH and FSH in mammals. Two GnRHs have been found in the chicken hypothalamus, cGnRH-I and -II. There is controversy as to whether either peptide can stimulate release of FSH in birds. The present studies compared the ability of cGnRH-I and -II to stimulate the release of FSH and LH in chickens. Lamprey (l) GnRH-III may be a specific-releasing factor for FSH, as it selectively stimulates FSH release in rodents and cattle, and has been detected in the hypothalamus of rodents, sparrows and chickens. Therefore, the ability of lGnRH-III to stimulate LH and FSH release was also examined. In our first experiment, the effects of cGnRH-I and -II were studied using 17-week prepubertal females. Intravenous injection of cGnRH-II at 1 and 10 microg/kg BW significantly increased LH secretion more than did cGnRH-I. Neither peptide significantly increased plasma FSH levels. In our second study, we administered cGnRH-I, -II or lGnRH-III to mature males maintained on a short photoperiod. cGnRH-II was again more potent than cGnRH-I in stimulating LH release, while lGnRH-III produced a modest LH rise. No GnRH peptide provided specific or potent stimulus to FSH secretion, although the high dose of cGnRH-II modestly enhanced FSH levels in the adult male (P < 0.05). Our results are not consistent with the view that lGnRH-III is a specific FSH-releasing hormone across multiple classes of vertebrates. We conclude that the mechanism by which independent release of FSH occurs in chickens remains unresolved.     

Administration of ticarcillin in combination with clavulanic acid intravenously and intrauterinely to clinically normal oestrous mares

Ticarcillin and clavulanic acid (potassium clavulanate) were administered to normal oestrous mares intravenously (i.v.) at a dose of 50 and 1.67 mg/kg for ticarcillin and clavulanate, respectively. In a crossover design, the same drugs were administered intrauterine (i.u.) at a dose of 12.4 and 0.4 mg/kg for ticarcillin and clavulanate, respectively. The i.u. dose was administered in 100 mL of saline solution. Endometrial tissue biopsies and plasma samples were collected after drug administration for the determination of ticarcillin and clavulanate concentrations by high-pressure liquid chromatography and pharmacokinetic calculations. After i.u. administration both drugs were poorly absorbed into the plasma. The ticarcillin half-life from tissue and plasma was short after i.v. administration. Although concentrations in tissue were higher after i.u. administration than i.v., concentrations of ticarcillin declined rapidly, which would necessitate frequent treatment in order to maintain drug concentrations above the minimum inhibitory concentrations (MIC) throughout the treatment period. Clavulanate concentrations in tissue were either low or persisted for only a short time after administration via either route. It appears that addition of clavulanate to the formulation for treatment of i.u. infections in mares is of questionable value based on these concentrations.     

菜豆新品种‘吉农油豆1号’

‘吉农油豆1号’是通过系统选育而成的菜豆常规品种。植株生长势强,分枝多,结荚部位低,花冠紫色。嫩荚绿色,宽刀形,荚长13～15cm,宽2.0～2.6cm,荚面较平,厚约1.3cm,单荚质量18～20g,每荚含种子6～7粒。种子椭圆形,深褐色,千粒质量约500g。嫩荚品质好,荚壁、荚面均无纤维。抗病,平均产量2.3t·h...     

农杆菌转化系统在蔬菜育种上的应用及常见问题的探讨

自从70年代,人们首次从分子水平上证实了农杆菌浸染植物,到1983年第一个转基因植物问世,农杆菌介导转基因工程已是日新月异,硕果累累,转化成功的植物达116种,利用农杆菌可侵染双子叶植物的特点,这种方法已被广泛地应用在蔬菜育种中。1 农杆菌转化系统的原理和方法 土壤农杆菌是一种革兰氏阴性菌,从该菌中分     

Marine natural products as prototype agrochemical agents

In the interest of identifying new leads that could serve as prototype agrochemical agents, 18 structurally diverse marine-derived compounds were examined for insecticidal, herbicidal, and fungicidal activities. Several new classes of compounds have been shown to be insecticidal, herbicidal, and fungicidal, which suggests that marine natural products represent an intriguing source for the discovery of new agrochemical agents.     

不同方式施用壳寡糖对甜瓜幼苗的影响

以“百亿唐帝”甜瓜为试材,采用双因素随机区组法,用不同浓度(25、50、75、100、125 mg·L^-1)的壳寡糖溶液分别进行浸种、叶喷和根灌处理,研究壳寡糖不同施用方式对甜瓜幼苗的影响,以期为壳寡糖在蔬菜育苗上的应用提供参考依据。结果表明：75 mg·L^-1壳寡糖浸种可极显著提高甜瓜种子的发芽率;其中75 mg·L^-1浸种、50 mg·L^-1叶喷、100 mg·L^-1根灌为各施用方式中增强甜瓜幼苗质量的最佳浓度;在施用方式中,以叶喷处理的甜瓜幼苗质量最佳,其次为根灌处理,浸种处理最弱,但均极显著高于对照。     

现代猪的生产潜力及其饲养措施

关于现代品种猪的生产潜力和商品猪生产的实际成绩及理想生产成绩的对比列下表。可以看出,采用最为先进的生产方式,猪从出生到上市平均每天增重700g是可以达到的,即在143日龄达到100kg体重。但事实上,实际生产中尚存在较大差距。有上千个关于现代品种猪的研究表明,猪从25～125kg     

Earth's free oscillations excited by the 26 December 2004 Sumatra-Andaman earthquake

At periods greater than 1000 seconds, Earth's seismic free oscillations have anomalously large amplitude when referenced to the Harvard Centroid Moment Tensor fault mechanism, which is estimated from 300- to 500-second surface waves. By using more realistic rupture models on a steeper fault derived from seismic body and surface waves, we approximated free oscillation amplitudes with a seismic moment (6.5 x 10(22) Newton.meters) that corresponds to a moment magnitude of 9.15. With a rupture duration of 600 seconds, the fault-rupture models represent seismic observations adequately but underpredict geodetic displacements that argue for slow fault motion beneath the Nicobar and Andaman islands.