紫花与杂花苜蓿再生影响因子的比较研究

对紫花苜蓿(Medicago sativa L.)(秘鲁、关中、甘农3号)及杂花苜蓿(Medicagovaria Martyn)(甘农1号、甘农2号)组培再生体系各影响因子进行比较研究。结果表明:紫花、杂花苜蓿的组培再生能力差异较大,前者显著高于后者;在愈伤组织诱导中,子叶节是最佳的外植体材料;2,4-D浓度增加对紫花苜蓿出愈率影响不明显,但杂花苜蓿的出愈率随着2,4-D浓度的增加呈明显的升高趋势;紫花苜蓿的最佳愈伤组织诱导培养基为MS₊2,4-D2.0mg/L+蔗糖30g/L,诱导率均在95%以上;杂花苜蓿为MS₊2,4-D 4.0mg/L+蔗糖30 g/L,两个品种诱导率分别为65.6%、73.3%;5个品种的最适分化培养基均为MS₊KT 1.0 mg/L+NAA 0.5mg/L+蔗糖20 g/L或MS₊BA4.0 mg/L,分化率也各有差异,紫花苜蓿不定芽的分化率可达到70%左右,而杂花苜蓿在30%左右;最佳诱导生根的培养基为1/2MS₊IBA 1.0 mg/L;本研究建立了紫花苜蓿高频再生组织培养体系,为实现外源基因的高效遗传转化奠定基础;通过紫花苜蓿和杂花苜蓿的再生体系影响因子的比较研究,为杂花苜蓿再生体系的建立提供参考。     

TDZ对仙客来不同外植体再生的影响

在无菌条件下培养仙客来种子,并以无菌萌发植株的子叶节、子叶、叶片及叶柄为外植体进行芽分化诱导。试验结果表明,不同浓度TDZ对各外植体的诱导效果不同,用子叶节、子叶、叶片及叶柄均可诱导出再生芽,但以叶片为材料的诱导效果最佳,其中1.0 m g/L TDZ对叶片再生芽的诱导效果最好,而子叶以0.5 m g/LTDZ、子叶节和叶柄以0.2 m g/L TDZ诱导再生芽的效果较好。     

The laboratory culture of Dichelobacter nodosus in a footrot eradication program

SUMMARY As part of a program to eradicate virulent footrot from Western Australia, 2745 isolates of Dichelobacter nodosus were isolated from 5263 specimens from 1883 submissions. The virulence of each isolate was assessed using protease thermostability and isoenzyme zymogram. We describe changes to the materials and methods required to handle these specimens and to reduce the interval between submission and report to 8 days.     

2016-2017年我国华北地区猪繁殖与呼吸综合征病毒类NADC30毒株分子遗传演化分析

为了解我国华北地区类NADC30流行猪繁殖与呼吸综合征病毒(PRRSV)及遗传变异情况,本研究自2016~2017年采集华北四省市(北京、天津、山东及河北)部分猪场疑似PRRSV样品239份进行RT-PCR检测,对所有阳性样品的ORF5基因测序分析及部分阳性样品病毒分离,并选择1株基因缺失病毒TJjh1602株进行全基因的序列扩增及分析.结果显示:PRRSV检测总阳性率44.35%(106/239),遗传进化显示52.83%(56/106)的流行毒株与类NADC30相近且位于系谱1(lineage 1),其中32.14%(18/56)的类NADC30流行毒株具有相同特征性的氨基酸位点缺失;TJjh1602株全基因长度为15018 nt,与NADC30同源性为95.2%,除具有上述特征性氨基酸位点缺失外,无其他插入或缺失.研究结果推测PRRSV类NADC30毒株在我国华北地区广泛流行,同时已遗传演化成一类具有ORF5缺失分子标签的新型类NADC30毒株,提示需进一步加强对PRRSV新型缺失毒株的流行病学调查及相关致病力研究.     

气候变化下三裂叶豚草在新疆的潜在地理分布

明确有害入侵种在区域尺度上的潜在分布及其对气候变化的响应对入侵种的预警和具体防控意义重大。三裂叶豚草是全球公认的恶性入侵杂草,目前已经大面积入侵“一带一路”中亚枢纽—新疆伊犁河谷。为有效防控三裂叶豚草在新疆的扩散蔓延,本研究基于最大熵模型,预测了当前及未来两种气候情景（RCP4.5, RCP8.5）下2050s和2070s时期三裂叶豚草在新疆的潜在分布及变化趋势。结果表明：当前气候下三裂叶豚草在新疆的总适生面积达24.01万km²,约占全疆面积的14%,在RCP4.5情景下,至2050s、2070s时期将分别增至37.36万和39.23万km²;在RCP8.5情景下,将分别增至39.45万和42.94万km²。在未来两种气候情景下,随着时间的推移,潜在适生区总体均呈现向北增加转移的趋势,减少区域主要集中在准噶尔盆地。所有环境因子中,与降水相关的因子总贡献率为40.1%,与温度相关的因子总贡献率56.0%,其中最干月降水（36.2%）、温度季节性变化标准差（29.1%）是对三裂叶豚草分布贡献率较高的环境因子。耕地和建设用地是三裂叶豚草入侵风险最高的区域。建议管理的重点除了放在已预测到的适生区内,还应特别关注农田、草场、道路两侧这些人畜扰动大、水分充足的区域。     

鸡胚胎期及生长发育早期对孵化绿光强度的反应

试验旨在探究孵化期单色绿光不同光照强度对鸡孵化和早期生长发育的影响。选用810个大小均匀的新浦东鸡种蛋,随机分为3组（n=270）,孵化期1~18.5 d分别在黑暗、低照度（20~50 lux）和高照度（200~300 lux）的LED单色绿光（λ=525 nm）条件下孵化,每天光照24 h,各组种蛋于第18.5天转至同一台无光出雏器中,各组温度和湿度等其他孵化条件始终保持一致。检测各组受精蛋孵化率、死胚率、初生重、10周龄体重、初生雏鸡及3周龄公鸡的血清激素浓度（甲状腺素、降钙素、生长激素、褪黑激素和骨钙素等）和血液生理生化指标（碱性磷酸酶、胰岛素样生长因子和钙等含量）。结果表明：各组种蛋的死胚数和死胚率差异较小;孵化的20.5 d低照度组和高照度组的受精蛋孵化率分别为黑暗组的2.3倍和5.2倍;孵化的21.5 d黑暗组的受精蛋孵化率为82.8%,低照度组和高照度组的孵化率分别比黑暗组高6.5%和1.9%;黑暗组的健雏率为98.6%,低照度组的健雏率比黑暗组低0.4%,而高照度组与黑暗组的健雏率接近;高照度组公雏初生重显著低于黑暗组（P<0.05）,而低照度组与黑暗组无显著差异（P>0.05）。母雏初生重趋势与公雏基本一致,高照度组母雏初生重显著低于其他两组（P<0.05）,其他两组之间无显著差异（P>0.05）;在10周龄,各组公鸡和母鸡体重无显著差异（P<0.05）;各组1日龄公雏血液生理生化和激素指标无显著差异（P>0.05）,3周龄公鸡高照度组和低照度组褪黑激素含量显著高于黑暗组（P<0.05）,其他指标无显著差异（P>0.05）。综上,在种蛋的孵化过程中,与黑暗条件下相比,给予适宜强度的单色绿光能够促进鸡胚发育,在不影响雏鸡健康的前提下使出雏时间提前,孵化期光照对后期生长发育影响较小。     

固相萃取-高效液相色谱-紫外检测土壤中多西环素

为了了解多西环素（DOX）在土壤中的污染现状,降低检测成本,本研究建立了固相萃取-高效液相色谱-紫外（HPLC-UV）检测3种土壤中DOX的分析方法。土壤样品通过采用乙腈和Na₂EDTA-Mcllvaine（1：1,V/V,pH 4.88）的混合溶液作为提取试剂,HLB固相萃取小柱进行富集净化,Agilent ZORBAX SB-C18（4.6 mm×250 mm×5 μm）色谱柱分离,以0.01 mol/L草酸（A）、乙腈（B）和甲醇（C）为流动相系统,在355 nm波长下进行高效液相色谱检测时提取效果最佳。以3倍信噪比确定方法检测限,以10倍信噪比确定方法定量限。结果表明,DOX在10 min出峰,在0.1~10 μg/mL范围内,DOX的峰面积与浓度线性关系良好,回归方程为y=22 747x+3.3256,相关系数是0.9999。本方法DOX的检测限为0.05 mg/kg,定量限为0.1 mg/kg。当土壤添加浓度为0.1 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为58.96%、75.84%和83.06%,变异系数为1.00%~9.54%;当土壤添加浓度为0.2 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为63.89%、70.48%和81.07%,变异系数为2.40%~8.83%;当土壤添加浓度为0.4 μg/g时,DOX在壤土、砂壤土及砂土中的回收率分别为59.02%、76.16%和81.29%,变异系数为1.52%~5.89%。本检测方法高效、稳定、特异性好,可以用于不同类型土壤中DOX的检测与定量,有助于环境中DOX检测方法的建立。     

Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4–15 years) had bred 2385 mares (mean age 9.4 years; range 3–24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to evaluate mare factors, including mare age, reproductive status, month of foaling, dystocia, month of cover, foal heat, cycle number, treatments, walk‐in status and stallion factors including stallion identity, stallion age, shuttle status, time elapsed between covers and high stallion usage on the per cycle pregnancy rate and pregnancy loss. Old age (p < 0.001) and cover within 20 days post‐partum (p < 0.003) were associated with lowered pregnancy rates. High mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss. Uterine inflammation or infection, if appropriately treated, did not affect fertility. Only high usage of stallions (used more than 21 times in previous week) was associated with lowered (p = 0.009) pregnancy rates. However, shuttle stallions were more likely to have increased (p = 0.035) pregnancy survival, perhaps reflecting a bias in stallion selection. In conclusion, mare age exerted the greatest influence on fertility; nonetheless, thoroughbreds can be effectively managed to achieve high reproductive performance in a commercial setting.     

Expression Analysis of THBS3 Gene in Different Tissues and Skeletal Muscles at Different Periods from Landrace and Tongcheng Pigs

To study the expression pattern of THBS3 gene in different tissues and during skeletal muscle development, the THBS3 gene expression in different tissues and skeletal muscles during prenatal periods (33, 45, 65, 70 and 90 d) and postnatal periods (0, 9, 30, 60, 120 and 160 d) from Landrace and Tongcheng pigs were detected by Real-time quantification PCR.The results showed that THBS3 gene widely expressed in all tissues examined, exhibiting similar spatial expression patterns with expression peaks in lung in both pig breeds except in stomach and intestine.Moreover, although THBS3 gene showed a significant higher expression level in gestation than after birth in Landrace and Tongcheng pigs (P<0.05), it exhibited different expression patterns between Landrace and Tongcheng pigs, the expression peak was detected at gestation day 45 in Landrace pig, while was detected at gestation day 65 in Tongcheng pig.The results suggested that THBS3 gene involved in skeletal muscle growth and development in pigs, as well as the regulation of asynchronization of skeletal muscle development in different pig breeds.