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991.
992.
[目的]血管紧张素转换酶2(ACE2)是RAS系统的关键调控酶,在动物上的研究较少,本试验研究了山羊ACE2的相关理化性质和功能。[方法]利用同源克隆及RT-PCR技术,根据牛的ACE2基因mRNA序列设计引物,从山羊肾脏组织中扩增出ACE2基因编码区的特异性片段,TA克隆到p MD19-T载体并转化至大肠杆菌DH5α感受态细胞,对生长出的单菌落进行验证后测序分析。根据测序分析结果设计引物,经PCR扩增和酶切连接,构建原核表达载体p ET-28a-ACE2,经过验证后转化大肠杆菌BL21(DE3)并用IPTG诱导表达ACE2蛋白。[结果]山羊ACE2基因c DNA编码区共包括2 415个核苷酸,编码804个氨基酸残基。同源性比对发现,山羊ACE2基因核苷酸序列同源性与绵羊ACE2最高,为99%,与斑马鱼最低,仅为60%。遗传进化分析也表明该ACE2基因与绵羊的遗传距离最近,与斑马鱼处在两个不同的分支上。蛋白结构及理化性质分析预测该山羊ACE2蛋白属于稳定型蛋白,蛋白信号肽序列位于第1氨基酸(aa)~18氨基酸(aa)之间,蛋白跨膜螺旋预测为Ⅰ型跨膜蛋白。成功构建山羊ACE2蛋白胞外部分(19~738 aa)表达载体,表达出的蛋白相对分子质量约为90×103,主要以包涵体的形式在BL21(DE3)中表达。[结论]本试验首次成功克隆了山羊ACE2基因编码区(基因序列号:KF921008.1),并对其蛋白结构及理化性质进行了初步预测,同时在大肠杆菌中高效表达了其胞外区蛋白。 相似文献
993.
994.
在乡村振兴大背景之下,结合乡村治理过程中存在的多元主体,以村级权力机制的重构为切入点,通过乡村善治当前存在的主要困境与理论阐述,构建一个对多元主体进行权力机制重构进而最终实现乡村善治目标的理论逻辑和分析框架.再基于浙江典型社区治理的案例,针对其中主体间权力架构发挥的作用进行分析,为乡村善治提供实践依据并反映现实意义,从而佐证了在村级多元主体权力机制重构的前提下最终实现乡村善治的现实可行性. 相似文献
995.
【目的】探究藏东南高山松林表层土壤养分的分布特征,为高山松林的可持续发展提供理论参考,为西藏生态安全屏障的建立提供指导。【方法】以藏东南林芝市4个地区(巴宜区、波密县、察隅县、米林县)高山松林为研究对象,于2019年9月采集、测定0~10 cm土层土壤的有机质(SOM)、全氮(TN)、全磷(TP)、全钾(TK)、碱解氮(AN)、速效磷(AP)、速效钾(AK)含量,并计算土壤化学计量比(C∶N、C∶P、N∶P),分析不同地区土壤养分含量、化学计量比的差异及土壤养分含量之间及其与土壤化学计量比之间的相关性,并分析土壤养分及其化学计量比与海拔、经度、纬度间的相关性。【结果】(1)高山松林表层土壤养分含量均较低,尤以土壤TP、AP含量最低,在全国第二次土壤普查养分分级标准中均处于“极缺”水平。除了土壤AP、AK属于强变异外,其他养分含量均属于中等变异。(2)不同地区土壤养分含量有差异,总体上察隅县、巴宜区较高,米林县、波密县较低。(3)高山松林表层土壤C∶N由大到小表现为米林县>巴宜区>察隅县>波密县。土壤C∶P、N∶P由大到小均表现为察隅县>波密县>巴宜区>米林县。(4)除了土壤TK与其他土壤养分(AP除外)间呈负相关外,其他土壤养分间均呈正相关关系。除了土壤C∶N与土壤TN、TK呈显著负相关以及土壤C∶P、N∶P与土壤TP呈极显著负相关外,土壤C∶N、C∶P、N∶P与其他土壤养分含量之间的相关性均不显著。(5)海拔与土壤AK呈显著正相关,与土壤其他养分含量及化学计量比之间的相关性不显著。经度、纬度与土壤养分含量和化学计量比之间的相关性均不显著。【结论】藏东南高山松林表层土壤养分瘠薄,尤以TP、AP含量较低,且土壤养分含量具有较大的空间变异性;受土壤氮、磷养分含量的影响,表层土壤C∶N、C∶P、N∶P均高于全国森林土壤。 相似文献
996.
Dipta DEY Tanzila Ismail EMA Partha BISWAS Sharmin AKTAR Shoeba ISLAM Urmi Rahman RINIK Mahmudul FIROZ Shahlaa Zernaz AHMED Salauddin AL AZAD Ahsab RAHMAN Sadia AFRIN Rezwan Ahmed MAHEDI Md. Nasir Uddin BADAL 《农业科学与工程前沿(英文版)》2021,8(4):603
997.
早孕因子的生物学特性及其在动物繁殖领域中的应用 总被引:2,自引:1,他引:1
早孕因子(early pregnancy factor,EPF)最初发现于孕鼠血清,是妊娠哺乳动物血清中存在的一种具有免疫抑制和生长调节作用的妊娠相关蛋白。EPF的氨基酸序列包括102个氨基酸残基,与伴侣蛋白10(chaperonin 10,Cpn10)高度同源,是Cpn10在细胞外发挥的效应,对温度、酸碱度的耐受性较强,无动物及品种特异性。其生物学特性主要体现在抑制免疫和生长调节两方面:①EPF具有抑制母体的免疫反应而使精子、胚胎免受免疫排斥的作用,也是目前最早确认妊娠的生化标志之一;②EPF能促进肿瘤细胞的生长,也能促进烧伤、溃疡等伤口的愈合。由于EPF能增强抗淋巴细胞血清抑制T细胞花环的形成,因此,玫瑰花环抑制试验是检测EPF活性的经典方法。EPF在动物繁殖领域可用于动物的早期、超早期妊娠诊断,妊娠中断的检测,胚胎移植后的成活情况检测,在评价雄性繁殖力和繁殖免疫疾病的治疗等方面有着重要价值。 相似文献
998.
Objective To measure associations between body weight, growth rate, sex, time of shearing and post-weaning mortality of Merino sheep.
Design Uni- and multivariable survival analyses of sheep mortality during the first year after weaning, using records (n = 3657) from two field experiments conducted in Western Victoria from 1996 to 2003.
Results Overall mortality was 14.3% (range 4.5–26.8%) and mean maximum mortality rate was 29 deaths/1000 weaners/month. Increased mortality risk was associated with decreases in fleece-free body weight and mean weaner growth rate, particularly at low weights and growth rates. Weaners in the lightest weaning weight quintile had a hazard ratio of 3.5, compared with the middle quintile. The hazard ratio for a 2-kg decrease in weaning weight was 1.2 to 1.7 for weaners lighter than 22 kg. The hazard ratio for a reduction in mean weaner growth rate in the first 5 months after weaning of 0.25 kg/month was 1.1 to 6.8 if mean growth rate was less than 1 kg/month, but did not differ significantly from 1 at greater growth rates. The hazard ratio for wether weaners was approximately 1.5 compared with ewe weaners. The hazard ratio for weaners shorn between December and May, compared with unshorn weaners, was 1.2 to 3.5, with the greatest risk difference associated with shearing in March (45 deaths/1000 weaners/month).
Conclusion Improving the body weight and mean growth rate of weaner sheep is likely to reduce post-weaning mortality. Lightweight weaners in a flock should be managed separately from the main portion after weaning. In southern Australia, not shearing spring-born Merino weaners between December and May may assist in reducing overall post-weaning mortality. 相似文献
Design Uni- and multivariable survival analyses of sheep mortality during the first year after weaning, using records (n = 3657) from two field experiments conducted in Western Victoria from 1996 to 2003.
Results Overall mortality was 14.3% (range 4.5–26.8%) and mean maximum mortality rate was 29 deaths/1000 weaners/month. Increased mortality risk was associated with decreases in fleece-free body weight and mean weaner growth rate, particularly at low weights and growth rates. Weaners in the lightest weaning weight quintile had a hazard ratio of 3.5, compared with the middle quintile. The hazard ratio for a 2-kg decrease in weaning weight was 1.2 to 1.7 for weaners lighter than 22 kg. The hazard ratio for a reduction in mean weaner growth rate in the first 5 months after weaning of 0.25 kg/month was 1.1 to 6.8 if mean growth rate was less than 1 kg/month, but did not differ significantly from 1 at greater growth rates. The hazard ratio for wether weaners was approximately 1.5 compared with ewe weaners. The hazard ratio for weaners shorn between December and May, compared with unshorn weaners, was 1.2 to 3.5, with the greatest risk difference associated with shearing in March (45 deaths/1000 weaners/month).
Conclusion Improving the body weight and mean growth rate of weaner sheep is likely to reduce post-weaning mortality. Lightweight weaners in a flock should be managed separately from the main portion after weaning. In southern Australia, not shearing spring-born Merino weaners between December and May may assist in reducing overall post-weaning mortality. 相似文献
999.
一氧化氮对猪腔前卵泡生长发育的影响 总被引:2,自引:0,他引:2
旨在研究在培养液中添加不同浓度(0、0.001、0.01、0.1和1 mmol.L^-1)的一氧化氮供体硝普钠(Sodium Nitroprusside,SNP)对猪腔前卵泡体外生长发育的影响。结果显示,体外培养后,各处理组卵泡直径均增加,但未达显著水平(P〉0.05);第6天1 mmol.L^-1SNP处理组卵泡存活率要显著低于1μmol.L^-1SNP(61.61%vs81.52%,P〈0.05),与其它各组间差异不显著(P〉0.05);卵泡成腔率在第4天以1μmol.L^-1SNP组最高,达到50%;第6天,1μmol.L^-1SNP组的卵泡成腔率显著高于0.1和1 mmol.L^-1SNP组(73.07%vs50%,47.62%,P〈0.05),也高于对照组和0.01 mmol.L^-1SNP组,但差异不显著(P〉0.05)。培养结束(6 d)后,除1mmol.L^-1SNP组卵母细胞正常率显著低于1μmol.L^-1SNP组(71.21%vs 48.18%,P〈0.05)外,其余各组间差异不显著(P〉0.05),其中0.001 mmol.L^-1SNP组卵母细胞正常率最高,为71.21%;0.001 mmol.L^-1SNP组COC回收率要显著高于其余各组(37.27%vs 22.88%、25.59%、20.74%和19.39%,P〈0.05)。结果表明,NO对猪腔前卵泡的存活、发育成腔及卵母细胞发育都有促进作用,但高浓度会产生毒性作用。 相似文献
1000.
EI Cortés-Gutiérrez F Crespo C Serres-Dalmau AL Gutiérrez de las Rozas MI Dávila-Rodríguez C López-Fernández J Gósalvez 《Reproduction in domestic animals》2009,44(5):823-828
Sperm DNA fragmentation (sDF) is an important parameter to assessing sperm quality. Information about sperm quality is not available for donkeys, especially in some breeds at risk of extinction. The objectives of this research were to test the four commercial variants of sperm chromatin dispersion test (SCD; sperm Halomax test), originally developed to assess sDF in boars, bulls, rams and stallions, in order to scrutinize their applicability in the study of sDF in a donkey breed at risk of extinction (Zamorano-Leonesa), for which there is no specific test available to analyze sperm at present. Only the SCD test, originally developed for stallions, produced stable and consistent results, and was deemed suitable to assess DNA fragmentation in sperm samples from donkeys. Image analysis was used to compare differences between the SCD methodology applied to stallion and donkey semen samples processed under the same experimental conditions. The extent of SCD in the SCD test was approximately 20% lower in donkey sperm than in stallion sperm. Yet, the ratio of chromatin sperm dispersion achieved in fragmented and unfragmented nuclei did not differ significantly between species. These data suggest that a similar protein depletion treatment can cause differences in protein removal in equivalent cells from different species and that sperm chromatin may be organized differently in stallions and donkeys. 相似文献