Myostatin down‐regulates the IGF‐2 expression via ALK‐Smad signaling during myogenesis in cattle

Myostatin (MSTN) is a negative regulator during muscle differentiation, whereas insulin‐like growth factors (IGFs) are essential for muscle development. MSTN and IGFs act oppositely during myogenesis, but there is little information on the mutual relationship of MSTN and IGFs. The present study was conducted to examine whether MSTN affects IGF expression during early myogenesis in cattle. IGF‐1 mRNA was similarly expressed in M. longissimus thoracis of double‐muscled (DM) and normal (NM) Japanese shorthorn cattle. IGF‐2 mRNA expression was consistently higher in the normal and regenerating muscle of DM cattle than those of NM cattle. When myoblasts were isolated from regenerating M. longissimus thoracis, IGF‐2 mRNA expression showed a significant increase in differentiating DM derived myoblasts (DM‐myoblasts) as compared with differentiating NM derived myoblasts (NM‐myoblasts). An addition of recombinant mouse myostatin (rMSTN) to myoblast cultures attenuated IGF‐2 mRNA expression and decreased myotube formation, but did not effect IGF‐1 mRNA expression. An activin‐like kinase (ALK) inhibitor, SB431542, mediates MSTN action, suppressed the translocation of Smad2/3 into the nucleus in DM‐myoblasts, and restored the attenuated IGF‐2 mRNA expression and the decreased myotube formation induced by rMSTN in myoblast cultures. The findings indicate that MSTN may negatively regulate myoblast differentiation by suppressing IGF‐2 expression via ALK‐Smad signaling.     

棉花纤维蛋白双向电泳体系的建立

[目的]探索一套适合于棉花纤维蛋白的双向电泳技术,为研究棉花纤维发育的蛋白质组学奠定基础.[方法]以陆地棉徐州142为材料,比较了三种不同蛋白质提取方法以及不同裂解液组成对双向电泳的影响,并在蛋白上样量和染色方法等方面进行了探索与优化.[结果]利用饱和酚-甲醇醋酸铵法提取的棉花纤维蛋白,其蛋白含量较高,且SDS-PAGE电泳条带清晰;样品溶解于含有硫脲和CHAPS的裂解液中,其蛋白溶解度增加;不同的蛋白上样量比较结果表明,第一向等电聚焦固相pH梯度胶条(7 cm)的最适上样量为300 μg;同时,经改良后的考马斯亮蓝染-脱色后,2-D图谱的背景清晰,分辨蛋白斑点数增加.[结论]研究建立了一套适用于棉花纤维蛋白总蛋白质组分析的双向电泳方法.     

Design and experimental validation of a novel double ring plate gear reducer

A novel double ring plate gear reducer (DRPGR) is designed and its experimental validation is conducted. By using the closed graph method, the modification coefficients of internal gearing in DRPGR are determined. Based on this, the overall structure of the reducer is designed and its kinematics simulation is achieved. With APDL programming language of ANSYS, a 3D finite element (FE) model of DRPGR is established, and its modal analysis and loaded tooth contact analysis (LTCA) are conducted respectively. The modal analysis reveals that the lower natural frequencies of DRPGR are much higher than the input frequency and the lower modes can be classified as vertical and horizontal bending of input and output shafts. The LTCA indicates that three pairs of gear teeth contact simultaneously at rated output torque. Due to the multi teeth contacts, the maximum stress is much lower than the permissible stress of internal gearings. The experimental tests of the prototype validate that DRPGR is adapted to both single driven and dual driven work condition. When single droved, DRPGR can eliminate the kinematic uncertainty by non 180 degree phase difference design. DRPGR claims a better dynamic performance in dual driven work condition. The efficiency of DRPGR increases with the increment of output torque and the reducer has an excellent short term overloaded capacity. The experimental results validate that the proposed method can be used to guide the design of that kind of reducer.     

黄土高原地区玉米双垄全膜覆盖沟播栽培技术土壤水温条件及其产量效应

田间比较玉米双垄全膜覆盖沟播栽培技术新型覆膜方式(SL)与其他覆膜方式———条膜起垄覆盖(TL),条膜平铺覆盖(TP),全膜平铺覆盖(QP)以及不覆膜(CK)在土壤含水量,土壤温度及玉米产量三个方面差别。分析结果显示:新型覆膜方式SL在作物苗期和成株期的表层土壤含水量最高,地表蒸发量较小,集水效果最好;在苗期的表层地温高于其他处理,超出对照6.1℃。各处理玉米产量从高到低次序为SLQPTLTPCK。其中SL比QP增加21.9%,比TL增加64.8%,比TP增加32.1%,较CK提高了1045%。SL的经济收益是QP的1.2倍,TL的1.7倍,TP的1.3倍,CK的10.2倍。双垄全膜覆盖沟播栽培技术是黄土高原半干旱区一项有效的增产和提高农民经济收入的措施。     

鸡传染性贫血病毒与禽网状内皮增生症病毒二重PCR检测方法的建立

当前养鸡业中鸡传染性贫血病毒、禽网状内皮增生症病毒混合感染的发生率日益增高,为提高CIAV、REV检测效率,根据GenBank上登录的CIAV全基因序列和REV的LTR序列分别设计了2对引物,建立了REV、CIAV二重PCR检测方法,另外还比较了2种不同的DNA提取方法。结果显示,该方法扩增目的条带清晰、敏感性高、特异性好。应用建立的方法对临床7份病料样品检测,检出5份CIAV、REV阳性,表明建立的二重PCR方法能有效用于CIAV、REV混合感染的临床诊断。     

Contact analysis of a new style planetary reducer with a double crank and internal gear board

To address the problems of low carrying capacity and short life of bearings in current ring reducers, a new type of ring reducer is proposed which consists of a two stepped transmission. One is a planetary transmission, and the other is an N type planetary transmission with a low tooth number difference. Based on the analysis of structural features, the transmission principle, and a transmission load situation, a contact finite element model of the new type of ring reducer is set up, and the stress value and the actual pairs of meshing teeth are derived by calculation. Based on gear modification research theory, the second stage transmission gear pairs of the new reducer are modified on its teeth profiles. Results demonstrate that the load capacity of transmission gear pairs have been enhanced greatly.     

Experimental research on heating performance of jetting mixing low pressure heaters

This paper conducts the experimental study on the performance of steam water two phase flow device composed by a nozzle,mixing chamber and the corresponding valves when the inlet steam pressure is in the range of 0.18~0.22 MPa．The experimental results show that the injector can run stably and reliably and the temperature of outlet water is increased obviously in low inlet steam pressure．This characteristics can be used as effective heaters in the engineering fields such as power plants,heating,the light industry, etc． When a single stage ejector can not meet the requirements of heating conditions, double stage ejectors can be used.     

玉米喷施大民先锋生物肥肥效试验

研究了玉米不同生育期叶面喷施大民先锋生物肥,对玉米全生育期、主要经济性状和产量的影响。结果表明：喷施生物肥可延长玉米全生育期,改善玉米主要经济性状和提高产量 相同施肥量条件下,在幼苗期、大喇叭口期和抽雄期各喷施1次的效果最好。     

平衡施肥对全膜双垄沟播春玉米产量及养分吸收规律的影响

[目的]研究干旱半干旱农作区全膜双垄沟播技术下,平衡施肥技术对春玉米产量及养分吸收规律的影响,旨在为该区春玉米高产栽培提供最佳施肥方案。[方法]以玉米品种沈单16为指示作物,通过全膜双垄沟播玉米田闯试验,研究了氮、磷、钾肥配合平衡施肥对玉米产量扣养分吸收规律的影响。[结果]全膜双垄沟播条件下,各处理中,玉米平均产量以OPT＋Zn处理最高,达到了12934．0kg／hm^2;适量增施Zn肥能有效提高玉米产量;氮磷钾养分累积均随肥料施入量的增加而增加,合理配施氮、磷、钾肥有利于养分的协调供应,提高春玉米植株体内的养分含量和吸收量。[结论]全膜双垄沟播条件下,平衡施肥显著提高了玉米的产量和经济收益;K是玉米高产的主要限制因子;生育后期养分的充足供应是玉米高产的关键。     

双吸盘小麦精密排种器参数设计与优化

为适应小麦精密播种的要求,对传统气吸式精密排种器进行改进,确定了各部件参数的取值范围。通过二次回归正交试验,分析吸孔直径、吸孔处压力和排种盘转速3个因素对合格率的影响,并建立了合格率的回归方程进行方差分析和拟合度检验。结果表明:影响小麦气吸式排种器合格率的因素依次为:排种盘型孔直径、吸孔处风压和排种盘转速;经回归方程优化得到各因素的最优组合为,吸孔直径2.6 mm、排种盘转速28.3 r/min、吸孔处压力2.28 kPa,此时排种器合格率达到97%,满足小麦精密播种的要求。改进后的小麦精密排种器结构简单,较传统气吸式精密排种器排种性能有较大提高。