广西巴马小型猪SP1基因克隆测序及其真核表达载体的构建

[目的]克隆广西巴马小型猪特异性蛋白1(SP1)基因,并构建其真核表达载体,为揭示其对猪生长发育的调控机理打下基础.[方法]利用RT-PCR从广西巴马小型猪背最长肌组织中扩增SP1基因,采用DNASTAR、TMHMM等分别进行基因生物信息学分析;以pEGFP-N1质粒构建真核表达载体pEGFP-N1-SP1并转染293T细胞,于转染48 h后在倒置荧光显微镜下观察并拍照.[结果]克隆获得的广西巴马小型猪SP1基因与GenBank中野猪(Sus scrofa)的参考序列(XM_005652569.3)一致,未发现碱基突变位点;其编码序列(CDS)全长2340 bp,编码779个氨基酸.广西巴马小型猪SP1蛋白不存在跨膜结构,也不存在信号肽,不属于分泌型蛋白;其二级结构中α-螺旋占17.84%,延伸链占21.31%,β-转角占9.76%,无规则卷曲占51.09%.构建的真核表达载体pEGFP-N1-SP1能成功转染至293T细胞中并表达出绿色荧光蛋白.[结论]广西巴马小型猪SP1基因CDS序列编码蛋白主要参与细胞内活动,而非外分泌型蛋白,以SP1基因构建的真核表达载体pEGFP-N1-SP1能转染293T细胞并成功表达,可直接用于后期SP1基因功能探索及干扰表达等研究.     

南方淮山炭疽病菌的致病力分化

[目的]明确我国南方淮山炭疽病病原菌种类及其致病力分化状况,为淮山炭疽病的综合防治和抗病育种提供理论依据.[方法]采用形态学观察,结合rDNA-ITS序列比对和系统发育进化分析,对从我国南方6省(区)四川、贵州、云南、广西、福建和海南淮山种植区典型炭疽病病叶分离获得的45株炭疽病病原菌进行鉴定,并通过接种在4种不同淮山种质(Do6-3、Do6、Do108和Do21)叶片上进行致病力检测,分析不同来源菌株的致病力差异.[结果]45株炭疽菌均鉴定为胶孢炭疽菌(Colletotrichum gloeosporioides).45株炭疽菌对4种淮山种质材料均能致病,根据综合致病力可将45株炭疽菌分为强、中、弱3种致病类型.其中,6株强致病性菌株均来自广西,7株弱致病性菌株主要来自云南,32株中等致病力菌株主要来自贵州、福建和海南.[结论]来源于我国南方6省(区)的45株淮山炭疽病病原菌均为胶孢炭疽菌(C.gloeosporioides),其致病力分化明显,且与地理来源具有相关性.     

辣木瑙螟幼虫虫龄的判定

[目的]明确辣木瑙螟幼虫最佳的分龄指标及幼虫虫龄数,为辣木瑙螟预测预报及防控提供基础资料.[方法]在实验室对辣木瑙螟幼虫头壳宽、体长和体宽3个外部形态指标进行测量,通过Dyar定律推断其龄数,并通过Crosby指数、Brook指数和回归分析对所测得的数据进行统计分析,判断分龄的合理性.[结果]辣木瑙螟幼虫分为5龄,1~5龄幼虫的头壳宽平均值分别为0.25、0.40、0.63、0.92和1.30 mm,体长平均值分别为2.09、3.69、6.10、10.09和12.93 mm,体宽平均值分别为0.34、0.57、0.94、1.33和1.92 mm.各龄幼虫头壳宽平均值的变异系数和Crosby指数最小,头壳宽与虫龄间的三次和二次线性拟合模型的相关系数最大(R2=0.9999),头壳宽与虫龄间指数拟合模型的相关系数(R2=0.9955)较高,拟合程度均较好.28℃下辣木瑙螟幼虫历期为10~13 d.[结论]辣木瑙螟幼虫分为5龄,头壳宽为辣木瑙螟幼虫虫龄判定的最佳指标,体长和体宽不适合用于辣木瑙螟幼虫虫龄的判定,其行为、体色和刚毛可为虫龄的判定提供参考.     

不同派系杨树品种(系)光合特性评价

[目的]综合评价引种的白杨派、黑杨派和青杨派杨树品种(系)的光合能力和生长优势,为优良杨树品种(系)推广种植提供参考依据.[方法]使用Li-6400XT便携式光合仪测定相同生境条件下伊犁地区引种白杨派、黑杨派和青杨派杨树品种(系)的光合参数,使用模糊数学中的隶属函数法综合评价各品种(系)的光合能力和生长情况.[结果]不同派系杨树品种(系)的光合速率(Pn)呈单峰或双峰曲线,部分品种(系)存在明显的光合午休现象;各派系内不同品种的光合生理参数差异显著(P<0.05)或极显著(P<0.01);大气CO2浓度(Ca)和气孔导度(Gs)对3个派系Pn的直接作用较大,蒸腾速率(Tr)为白杨派树种的主要决策变量,叶温(Tl)为黑杨派和青杨派树种的主要决策变量,影响白杨派和青杨派树种Pn的主要限制变量为Ca,黑杨派则为胞间CO2浓度(Ci).沙兰杨(辽宁)、银×新12#、171、174、银×新中东杨、银×新192的综合指数较高.[结论]银×新中东杨、沙兰杨(辽宁)、银×新12#、林场银×新、171和银×新192的光合能力较强且生长优势明显,各项指标的综合指数较高,适应高光强环境能力较强,可在新疆伊犁平原地区及其他适宜种植白杨派、黑杨派和青杨派树种的平原地区推广种植.     

组合桨搅拌槽内部流场数值模拟

针对组合桨组合形式在不同应用场合的匹配问题,采用计算流体力学(CFD)的分析方法,基于Fluent仿真软件,分析双螺带及六斜叶涡轮桨基于不同组合位置的内部流场情况采用多重参考系(MRF)方法建立基础模型,基于Navier-Stokes方程和标准k-ε湍流模型对搅拌槽内部流体产生的流场进行数值计算,得到搅拌桨在240 r/min的搅拌转速下产生的流场数据.分析搅拌器在特定界面处轴向、周向、径向的速度矢量图以及其综合速度云图,并对位置互换的流场进行分析和比较,选出上双螺带桨下涡轮桨为最佳的桨叶组合形式,此种组合桨型对于提升搅拌器在相关领域的应用和发展等有参考价值.     

北京山区河岸植被的水土保持效益

通过野外简易径流小区的放水冲刷试验,研究北京山区河岸带不同植被类型水土保持效果差异。试验设计4,6,8L/min 3种上方来水流量以及6种植被类型小区坡面,冲刷历时31min,试验过程收集径流泥沙样,分析不同径流小区的产流产沙特征。结果表明:(1)各植被类型小区平均总产流产沙量(43.29L/m~2,0.71kg/m~2)均显著小于裸坡下平均总产流产沙量(65.86L/m~2,3.21kg/m~2)(p0.05)。植被具有明显的减流减沙效益,且减沙效益(78.66%)大于减流效益(36.16%);(2)不同植被类型间减流减沙效果不同,随着放水流量的上升,坡面产流速率、产沙速率不断上升,其中以狗牙根小区平均产流速率(6.16L/min)、平均产沙速率(55.50g/min)最小,水土保持效益较好;(3)不同植被类型小区稳定入渗速率差异显著(p0.05),均大于裸坡条件下的稳定入渗速率(42mm/h),其中以狗牙根小区坡面的径流稳定入渗速率最大(129.0mm/h)。综上所述,植被具有明显的蓄水保土效益,且不同的植被类型间减流减沙效果差异显著。研究结果为北京山区河岸带进行生态环境安全建设以及生态修复提供了基础理论依据,并且为河岸边坡的植被修复物种选择提供了参考依据。     

名山河流域不同类型土壤腐殖质的组成特征

以名山河流域不同类型土壤为研究对象,研究了3种土壤类型(黄壤、紫色土、水稻土)和4种土地利用方式(水田、旱地、果园、茶园)下腐殖质的组成特征。结果表明:名山河流域3种类型土壤腐殖质含碳量为9.74~21.66g/kg,表层土壤(0—20cm)大于下层土壤(20—40cm),含量由高到低依次为水稻土紫色土黄壤,水稻土与紫色土、黄壤腐殖质碳含量差异显著,腐殖质各组分碳含量间呈极显著正相关(P0.01);从土地利用方式看,水田腐殖质含碳量显著高于果园、茶园和旱地,且腐殖质碳含量与HA含量呈极显著正相关(P0.01);土壤的腐殖化程度表现为黄壤紫色土水稻土。不同利用方式下重组碳含量表现为水田果园茶园旱地,茶园表层土壤腐殖质松紧比最大(1.37),为水田下层土壤的2.14倍;3种类型土壤团聚体中HA含量为0.02~4.57g/kg,且随着粒径的减小呈现先降低后增加的趋势,除2~5,0.25mm粒径团聚体外,5,1~2,0.5~1,0.25~0.5mm粒径团聚体均与其HA含量呈正相关(P0.05)。土壤腐殖质组成受土壤类型及人为耕作管理活动的影响,4种土地利用方式下水田土壤肥力最高,HA含量受5mm粒径团聚体影响最大。     

Effects of dietary forage to concentrate ratio and wildrye length on nutrient intake,digestibility, plasma metabolites,ruminal fermentation and fecal microflora of male Chinese Holstein calves

Twenty-eight male, weaned Chinese Holstein calves((156.8±33.4) kg) were used to investigate the effects of dietary forage to concentrate ratio(F:C) and forage length on nutrient digestibility, plasma metabolites, ruminal fermentation, and fecal microflora. Animals were randomly allocated to four treatments in a 2×2 factorial arrangement: whole-length forage(WL) with low F:C(50:50); WL with high F:C(65:35); short-length forage(SL) with high F:C(65:35); and SL with low F:C(50:50). Chinese wildrye was used as the only forage source in this trial. The grass in the SL treatments was chopped using a chaff cutter to achieve small particle size(~50% particles 19 mm). Dry matter intake(DMI) and organic matter(OM) intake was increased by increasing both F:C(P0.01) and forage length(FL)(P0.05), while acid detergent fiber(ADF) and neutral detergent fiber(NDF) intakes were only increased by increasing the F:C(P0.01). The digestibility of NDF was increased as the FL increased(P0.01), and it was also affected by interaction between F:C and FL(P0.05). Cholesterol(CHO)(P0.01), leptin(LP)(P0.05), and growth hormone(GH)(P0.01) concentrations in plasma were increased as dietary F:C increased. A significant increase in plasma triglyceride(TG)(P0.01), insulin(INS)(P0.05), and GH(P0.01) levels was observed with decreasing dietary FL. Ruminal p H values of calves fed with low F:C diets were significantly lower than those in high F:C treatment(P0.05). Increasing the F:C enhanced ruminal acetic acid(P0.05) and acetic acid/propionic acid(P0.01). Fecal Lactobacillus content was significantly higher, while Escherichia coli and Salmonella contents were significantly lower in WL and high F:C groups(P0.05). Lower fecal scores(higher diarrhea rate) were observed in calves fed with SL hay compared to WL hay(P0.05). Denatured gradient gel electrophoresis(DGGE) bands and richness index(S) were significantly affected by the interaction between F:C and FL(P0.05), under high F:C, band numbers and richness index from WL group were higher than that from SL group(P0.05), whereas there were no differences between WL andSL groups under low F:C(P0.05). Microflora similarity was 50–73% among the different treatments. It is concluded that the WL with high F:C(65:35) diet is suitable for weaned calves.     

Effects of lairage after transport on post mortem muscle glycolysis,protein phosphorylation and lamb meat quality

The objective of this study was to investigate the effect of lairage after transport on post mortem muscle glycolysis, protein phosphorylation and lamb meat quality. Two preslaughter animal treatments, transport for 3 h and lairage for 0 h (T3L0) and transport for 3 h and then lairage for 12 h (T3L12), were compared with a control treatment of 0 h transport and 0 h lairage. Data obtained showed that preslaughter transport had a significant effect on lamb meat quality. Loins from lambs of the T3L0 treatment showed higher (P=0.026) pH_{24 h} and higher (P=0.021) pH_{48 h} values, but lower (P<0.001) drip loss and lower (P<0.05) glycolytic potential at 0 h post mortem than those of the T3L12 and control groups. Muscle samples of the T3L0 group showed higher (P=0.046) shear force and lower (P=0.005) b* value than those of the T3L12 group. Muscle glycogen concentration at 0, 2, 4 h post mortem were lower (P<0.05) in the T3L0 group than in control. No significant difference (P>0.05) in most meat quality parameters was determined between the T3L12 group and control, showing lairage for 12 h allowed lambs to recover from the effects of transport for 3 h and resulted in similar meat quality characteristics compared to no transport. Lairage after transport did not affect most meat quality indices in comparison with control, but increased the meat drip loss and b* value of lambs possibly through decreasing glycogen concentration and glycolytic potential.     

Impacts of silicon on biogeochemical cycles of carbon and nutrients in croplands

Crop harvesting and residue removal from croplands often result in imbalanced biogeochemical cycles of carbon and nutrients in croplands, putting forward an austere challenge to sustainable agricultural production. As a beneficial element, silicon (Si) has multiple eco-physiological functions, which could help crops to acclimatize their unfavorable habitats. Although many studies have reported that the application of Si can alleviate multiple abiotic and biotic stresses and increase biomass accumulation, the effects of Si on carbon immobilization and nutrients uptake into plants in croplands have not yet been explored. This review focused on Si-associated regulation of plant carbon accumulation, lignin biosynthesis, and nutrients uptake, which are important for biogeochemical cycles of carbon and nutrients in croplands. The tradeoff analysis indicates that the supply of bioavailable Si can enhance plant net photosynthetic rate and biomass carbon production (especially root biomass input to soil organic carbon pool), but reduce shoot lignin biosynthesis. Besides, the application of Si could improve uptake of most nutrients under deficient conditions, but restricts excess uptake when they are supplied in surplus amounts. Nevertheless, Si application to crops may enhance the uptake of nitrogen and iron when they are supplied in deficient to luxurious amounts, while potassium uptake enhanced by Si application is often involved in alleviating salt stress and inhibiting excess sodium uptake in plants. More importantly, the amount of Si accumulated in plant positively correlates with nutrients release during the decay of crop biomass, but negatively correlates with straw decomposability due to the reduced lignin synthesis. The Si-mediated plant growth and litter decomposition collectively suggest that Si cycling in croplands plays important roles in biogeochemical cycles of carbon and nutrients. Hence, scientific Si management in croplands will be helpful for maintaining sustainable development of agriculture.