Production of Lambs After the Transfer of Fresh and Cryopreserved in vitro Produced Embryos from Prepubertal Lamb Oocytes and Unsorted and Sex-sorted Frozen-thawed Spermatozoa

Cumulus-oocyte complexes from hormone-stimulated 3-4-week-old (n=43) and 6-7-week-old (n=12) prepubertal lambs were matured in vitro and incubated with unsorted, or X- or Y-spermatozoa separated with a high-speed cell sorter (SX MoFlo)frozen-thawed. Presumptive zygotes were then cultured to the blastocyst stage, and transferred to recipients fresh or after cryopreservation (frozen). Oocyte cleavage was higher (p <0.05) with unsorted (515/926, 55.6%) than X- or Y-spermatozoa (261/672, 38.8% and 229/651, 35.2%, respectively) and blastocyst formation (% zygotes) by Day 9 of in vitro culture was lower (p <0.05) for X- (102/261, 39.1%) than unsorted spermatozoa (249/515, 48.3%), but did not differ between Y-spermatozoa (103/229, 45.0%) and unsorted spermatozoa, or between X- and Y-spermatozoa (p >0.05). For fresh embryos, survival to term was 50.0% (3/6) for unsorted, 0.0% (0/6) for X- and 16.7% (1/6) for Y-spermatozoa-derived embryos (p >0.05), and for frozen embryos was 4.0% (2/50) for unsorted, 9.1% (2/22) for X- and 2.9% (1/34) Y-spermatozoa-derived embryos (p >0.05). Of the two lambs born from X-spermatozoa-derived embryos, one was female (50%), and from the two Y-spermatozoa-derived lambs, both were male (100%), demonstrating that lambs can be produced after the transfer of fresh and cryopreserved IVP embryos derived from prepubertal lamb oocytes and frozen-thawed sex-sorted sperm.     

Preference of Sheep for Three Forms of Mucuna Forage and the Effect of Supplementation with Mucuna Forage on the Performance of Sheep

Assessment of the preference of sheep for fresh, dried or ensiled forms of mucuna (Mucuna pruriens var utilis) forage was followed by investigations into the effect of supplementing straw-based diets with the forage. Four sheep were offered fresh, dried and ensiled forms of the forage in a cafeteria style to assess their preference. In the second experiment, 20 sheep were randomly assigned to four dietary treatments, namely, alkali-treated straw only (M0), treated straw supplemented with mucuna forage at 0.3% (M10), 0.6% (M20) or 0.75% (M25) of body weight (approximately 10%, 20% and 25%, respectively, of the total dry matter intake). The daily feed intakes were determined and the sheep were weighed weekly for 10 weeks. The sheep showed a marked preference for fresh mucuna forage over either the dried or ensiled forms. The total dry matter intake increased by 15% and 21%, respectively, with M20 and M25. All the groups lost weight over the feeding period. However, only M0 gave weight losses during the second half of the feeding period. The feed conversion efficiency followed a trend similar to that for weight gains. M20 had the greatest effect on growth and feed conversion efficiency.     

百菌清在番茄上的自然消解动态及健康风险研究

试验设喷施百菌清推荐剂量(2 400g/hm2,T1)、加倍剂量(4 800g/hm2,T2)、喷清水(对照)3个处理。探讨蔬菜上百菌清残留量的安全性,开展番茄中百菌清残留的消解规律试验。结果表明,百菌清在番茄上的自然消解速度随施药剂量的增大而减慢。喷药后24h内消解最快,T1处理和T2处理施药后1d的消解率分别为60.22%和27.58%,7d的消解率达91.72%和46.67%,其半衰期分别为4.3d和18.0d。按推荐剂量施药1d后采摘,番茄中百菌清残留量为0.370mg/kg,符合国家相关标准的规定;从人体健康风险角度分析,如果按规范施药,百菌清在番茄上施用安全,产品食用无健康风险。     

小麦航天诱变后代的条锈病抗性变异及选择效果研究

为明确小麦航天诱变后代条锈病抗性的变异和选择效果,在甘肃陇南用系谱法对8个小麦品种的诱变后代进行了研究。结果表明,兰天10号、兰天14号、兰天17号在SP1(诱变一代)和SP2(诱变二代),PASCAL和85-173-4在SP2的群体病谱均较原品种对照发生了不显著的变异,但它们在SP1和SP2都没有出现显著的条锈病抗性突变体;郑麦9023、陇原031和DORICO在SP2均出现了显著的条锈病抗性突变系且有分离现象。8个品种的SP2和SP3(诱变三代)共获得9个显著的条锈病抗性突变系和12个显著的非条锈病抗性突变系,其中15个突变系的后代都出现了条锈病抗性的分离和变异。经过4代的选择,证明感病品种在SP2出现的抗性不显著提高株系具有一定的选择可靠性,从郑麦9023和陇原031中分别获得了抗条锈、大粒和兼抗条锈、白粉病的优良突变系。这些结果表明,航天诱变小麦种子能够引起后代条锈病抗性的丰富变异;变异可能出现在SP1、SP2或以后世代;对于感病品种在SP2出现的抗性不显著提高株系可以进行选择;不论哪一方面性状的显著突变系,一般会随世代进展出现条锈病抗性的分离和变异,都应作为抗性选择的目标对象而注意保留。     

钙调素与核酸在梨花芽分化中的动态研究

以梨为试格,对成花过程中ＣａＭ和核酸的含量进行了分析测定,结果表明;短枝芽的ＣａＭ含量在成花的发端期成倍增加形成高峰,而新梢芽却一直保持较低的水平;短果枝叶的ＣａＭ与新梢叶有着相近的变化趋势。但在成花前后,短果枝叶的ＣａＭ含量要明显高于新梢叶的,短枝芽所含核酸,尤其是ＲＮＡ开始回升时与ＣａＭ的峰值相吻合,并且在整个成花期间都呈上升的趋势。     

小麦骨干亲本生选6号的赤霉病抗性遗传分析

为研究生选6号对黄淮麦区小麦赤霉病抗性改良效果,以黄淮麦区矮抗58、周麦25、周麦27、兰考161等4个主栽品种(系)为母本,以生选6号为父本,配制杂交组合,分别在长江中下游地区(上海崇明、安徽滁州)和黄淮地区(河南兰考)对4个组合F2群体进行赤霉病抗性鉴定。结果表明,4个组合的F2群体赤霉病抗性较感病亲本均显著提高,平均病小穗率在18.4%~31.2%之间,均达到中抗水平。4个群体的个体抗性级别主要集中在抗病和中抗,平均约占80%;而中感、感病和高感很少,平均占比20%左右。矮抗58/生选6号F2群体在滁州和兰考两个不同生态区域的抗性差异显著,虽然两地均达中抗水平,但滁州点抗性明显优于兰考点。主要表现为兰考点高感单株数是滁州点的7.4倍,中抗单株数却不到滁州点的1/2。同时,兰考点抗感比为65∶35,而滁州点为89∶19,这种现象应该与当年两地气候差异有关,可能黄淮冬麦区当年气候更适合赤霉病发病,也与长江中下游品种大多中抗以上而黄淮品种大多为高感品种的事实相一致。此外,抗性单株从F2到F3,发生了接近3∶1的抗感分离,F3抗性单株的平均病小穗率为20.2%,仍保持较强赤霉病抗性。上述结果表明,生选6号可以作为骨干亲本,广泛用于黄淮冬麦区小麦赤霉病抗性的改良。