抗氧化剂在公猪精液冷冻保存中的应用

近几年来,在公猪精液冷冻稀释液中添加抗氧化剂以提高冷冻精液质量的研究受到广泛的关注。添加谷胱甘肽、超氧化物歧化酶和过氧化物酶、维生素E、L-半胱氨酸和L-谷氨酰胺、中草药成分等抗氧化剂可以有效地防止氧化损伤,提高解冻后精子活率、精子成活力、质膜与顶体完整性等,进而提高冷冻保存精液的受精能力。作者综述了抗氧化剂的抗精子冷冻损伤的作用机制及不同抗氧化剂的应用效果,并对其在公猪精液冷冻保存中的应用前景进行了展望。     

二八灰土回填地下粮仓浮力预警试验研究

地下结构的浮力多以阿基米德定律为基础进行计算,未考虑周围回填土体。该文以某地下粮仓为研究对象,考虑周围回填二八灰土的实际工况,分别进行直径为400(模型筒A)、500(模型筒B)、600 mm(模型筒C)的室内缩尺模型试验。试验包含纯水试验和回填二八灰土试验。纯水试验结果表明,以阿基米德定律计算的实际浮力与模型筒自重(包含模型筒上部约束反力所折算自重)的理论浮力基本一致,模型筒A、B、C的实际浮力与理论浮力的误差分别为0.03%、1%、3%。在回填二八灰土试验中,通过缓慢注水,利用位移计、压力传感器监测模型筒位移及模型筒上部的约束反力,分析了模型筒整个上浮过程中位移和约束反力的变化情况。位移突变值滞后于约束反力突变值,压力传感器读数发生明显变化而位移计读数未发生明显变化所测量的水位为警戒水位,压力传感器与位移计读数均发生明显变化所测量的水位为实际起浮水位。以警戒水位和实际起浮水位作为理论计算依据,得出警戒水位和实际起浮水位时模型筒自重(包含模型筒上部约束反力所折算自重)作用下理论抵抗浮力及计算所得的实际抵抗浮力。警戒水位时模型筒A、B、C实际抵抗浮力为理论抵抗浮力的1.93、2.43、1.66倍。实际起浮水位时模型筒A、B、C实际抵抗浮力为理论抵抗浮力的2.15、3.36、2.96倍。从安全储备方面综合考虑,回填工况地下粮仓在预警水位时实际抵抗浮力为理论抵抗浮力的1.5倍,实际起浮水位时抵抗浮力为理论抵抗浮力的2倍,研究结果为今后地下粮仓及其他地下结构的抗浮设计提供参考。     

制霉菌素抗饲料霉变性能的研究

以蛋鸭料为基础，分别在粉状料和颗粒料中添加制霉菌素、丙酸钙、霉敌３种抗真菌制剂，比较了三种抗真菌剂的抗饲料霉变功效．结果表明：颗粒料中的真菌比粉状料明显降低，３种抗菌制剂都有明显的抗真菌效果．其中制霉菌素与霉敌的抗霉菌生长效果优于丙酸钙，并能完全抑制黄曲霉、毛霉、根霉的生长，制霉菌素能显著降低饲料中黄曲霉毒素Ｂ１的含量．添加制霉菌素后粉状料的保质期为５０ｄ，颗粒饲料为６０ｄ，与霉敌基本一致：粉状料添加制霉菌素组比丙酸钙组保质期延长１０ｄ，颗粒料保质期可延长２０ｄ左右．几种处理条件下，当日粮中真菌总数发生明显变化时，饲料中ＣＯ２量也明显增加，因此，应用饲料中ＣＯ２含量作为衡量霉菌总数是一个比较敏感的指标．     

用原生质体融合进行冬菇育种的研究

用灭活的〔Flammulinasubnudus (Pr .)Sing〕双核菌株原生质体与〔Flammulinavelutipes (Fr.)Sing〕双核菌株原生质体融合 ,在 2 2℃的条件下筛选得融合子。融合频率为 0× 10 -5～ 4 1× 10 -5。融合子与双亲有明显的拮抗性。融合子的菌丝体形态 ,氨基酸含量 ,子实体的形态 ,以及酸性磷酸酶的测定都与双亲不同。     

阔叶红松林倒木贮量动态研究

本文研究了中国吉林省长白山区阔叶红松林倒木贮量的动态变化规律。阔叶红松林倒木贮量包括其现有倒木及其年输入量等贮量的变化规律。阔叶红松林现有倒木贮量开始为16.25 t·hm-2,以后随时间减少,到100年分解掉其干重的85%左右,300年后所剩无几。倒木年输入量平均约为0.6 t·hm-2,其贮量是随时间而增加,200年后稳定在31 t·hm-2,可保持到该群落的顶级时期。倒木总贮量的变化在初期呈增加趋势,而后随着现有倒木的完全分解,倒木贮量就与其倒木的年输入趋于一致,最后稳定在上述水平上。图4表2参9。     

云联众家团购网在高校开展的可行性研究

云联众家团购网作为众多电子商务平台中的一个,在其行业发展中,也已经实现了对 大学生消费渗透。本文以福州外语外贸为例,对云联众家团购网在高校开展的可行性研究进行 了分析,旨在本文研究帮助下,能够更好地为云联众家团购网高校推广提供参考。     

株型对玉米群体光合速率和产量的影响

在大田条件下，采用人工改变株型的方法，比较了原型（平展型）与改型（紧凑型）玉米不同密度的群体光合速率，结果表明，改型群体光合速率比原型平均提高１７．２％，籽粒产量增加５．３％￣８．６％。抽丝期群体光合速率和籽粒产量之间呈极显著的正相关（ｒ＝０．８６９２）。改型玉米群体内光合有效辐射、ＣＯ２浓度分布比原型相对的“均匀”，是群体光合速率较高的重要原因，认为玉米作物的优化群体结构为紧凑型玉米个体所组成的     

褐藻酸钠涂膜剂的特性研究

对褐藻酸钠凝胶经冻结和解冻处理后的持水能力、凝胶强度、弹性、韧性及状态变化等特性进行了比较试验。结果表明；褐藻酸钠凝胶的这些性质与凝胶体内的钠和钙的比率直接相关；采用２％的褐藻酸钠溶液与５％的氯化钙溶液凝胶化２ｍｉｎ，所形成的凝胶具有很好的涂膜性能。     

Role for the membrane receptor guanylyl cyclase-C in attention deficiency and hyperactive behavior

Midbrain dopamine neurons regulate many important behavioral processes, and their dysfunctions are associated with several human neuropsychiatric disorders such as attention deficit hyperactivity disorder (ADHD) and schizophrenia. Here, we report that these neurons in mice selectively express guanylyl cyclase-C (GC-C), a membrane receptor previously thought to be expressed mainly in the intestine. GC-C activation potentiates the excitatory responses mediated by glutamate and acetylcholine receptors via the activity of guanosine 3',5'-monophosphate-dependent protein kinase (PKG). Mice in which GC-C has been knocked out exhibit hyperactivity and attention deficits. Moreover, their behavioral phenotypes are reversed by ADHD therapeutics and a PKG activator. These results indicate important behavioral and physiological functions for the GC-C/PKG signaling pathway within the brain and suggest new therapeutic targets for neuropsychiatric disorders related to the malfunctions of midbrain dopamine neurons.     

Partial replacement of fishmeal with Clostridium autoethanogenum single‐cell protein in the diet for juvenile black sea bream (Acanthopagrus schlegelii)

Clostridium autoethanogenum protein (CAP) is a single‐cell protein derived from ethanol production and may have potential to become a substitute for fishmeal in aquafeeds. A 70‐day feeding trial was conducted with black sea bream (Acanthopagrus schlegelii) (mean initial weight 6.03 ± 0.09 g) to evaluate partial replacement of fishmeal with CAP in diets. Seven isonitrogenous and isoenergetic diets were formulated with graded levels of CAP (0, 4.85, 9.70, 14.55, 19.40, 38.80 and 58.20%) to replace fishmeal. The inclusion of CAP at all dietary levels tested did not significantly affect the growth performance (p > .05). Fish fed the CAP58.20% diet showed a significantly lower feeding rate, with significantly higher protein efficiency ratio and feed efficiency ratio compared with fish fed the other diets (p < .05). No statistical differences were found in dorsal muscle and whole‐body compositions. Total superoxide dismutase in serum of fish fed CAP58.20% diet was significantly lower compared with that of the control. Malondialdehyde, catalase, total antioxidant capacity and digestive enzyme activities revealed no significant differences among dietary treatments. Phosphorus retention efficiency significantly increased, and phosphorus discharge showed a downward trend with increasing CAP inclusion levels. In conclusion, the results indicated that CAP is a safe and effective alternative protein source, which can replace fishmeal in the diet of black sea bream up to 58.20%, without adverse effects on growth performance, antioxidation and digestive enzyme activity. This study has shown the potential of converting industrial waste into a high protein feed ingredient for aquafeeds.