玉米胚芽油提取方法及特性研究进展

综述了水代法、压榨法、水酶法等玉米胚芽油的主要提取方法、以及其稳定性和生理功能,指出玉米胚芽油因氧化稳定性强、具有降低胆固醇的作用而具有广阔的市场前景.     

Fertilization and early embryonic development in heifers and lactating cows in summer and lactating and dry cows in winter

Two experiments in two seasons evaluated fertilization rate and embryonic development in dairy cattle. Experiment 1 (summer) compared lactating Holstein cows (n = 27; 97.3 +/- 4.1 d postpartum [dppl; 40.0 +/- 1.5 kg milk/d) to nulliparous heifers (n = 28; 11 to 17 mo old). Experiment 2 (winter) compared lactating cows (n = 27; 46.4 +/- 1.6 dpp; 45.9 +/- 1.4 kg milk/d) to dry cows (n = 26). Inseminations based on estrus included combined semen from four high-fertility bulls. Embryos and oocytes recovered 5 d after ovulation were evaluated for fertilization, embryo quality (1 = excellent to 5 = degenerate), nuclei/embryo, and accessory sperm. In experiment 1, 21 embryos and 17 unfertilized oocytes (UFO) were recovered from lactating cows versus 32 embryos and no UFO from heifers (55% vs. 100% fertilization). Embryos from lactating cows had inferior quality scores (3.8 +/- 0.4 vs. 2.2 +/- 0.3), fewer nuclei/embryo (19.3 +/- 3.7 vs. 36.8 +/- 3.0) but more accessory sperm (37.3 +/- 5.8 vs. 22.4 +/- 5.5/embryo) than embryos from heifers. Sperm were attached to 80% of UFO (17.8 +/- 12.1 sperm/UFO). In experiment 2, lactating cows yielded 36 embryos and 5 UFO versus 34 embryos and 4 UFO from dry cows (87.8 vs. 89.5% fertilization). Embryo quality from lactating cows was inferior to dry cows (3.1 +/- 0.3 vs. 2.2 +/- 0.3), but embryos had similar numbers of nuclei (27.2 +/- 2.7 vs. 30.6 +/- 2.1) and accessory sperm (42.0 +/- 9.4 vs. 36.5 +/- 6.3). From 53% of the flushings from lactating cows and 28% from dry cows, only nonviable embryos were collected. Thus, embryos of lactating dairy cows were detectably inferior to embryos from nonlactating females as early as 5 d after ovulation, with a surprisingly high percentage of nonviable embryos. In addition, fertilization rate was reduced only in summer, apparently due to an effect of heat stress on the oocyte.     

Symposium review: Predicting pregnancy loss in dairy cattle

Several tools exist to diagnose pregnancy in dairy cattle. However, substantial pregnancy loss occurs within the first 60 d of gestation in cattle, and these losses have a profound adverse economic impact on the dairy and beef cattle industries. Detecting these impending pregnancy losses could offer producers an opportunity to reduce costs associated with this source of reproductive inefficiency. Several of the pregnancy diagnostic tools currently available and new technologies are being examined for their ability to predict pregnancies at risk for failing in early pregnancy. This review provides a synopsis of work undertaken recently to predict pregnancy losses in cattle. Currently, opportunities to predict pregnancy loss include (1) using transrectal ultrasonography to detect loss of the fetal heartbeat, floating debris within the placental fluids, and reductions in fetal size; (2) observing reductions in circulating progesterone concentrations; (3) detecting reductions in concentrations of circulating placental products; namely, pregnancy-associated glycoproteins and microRNAs; and (4) detecting reductions in the early pregnancy-dependent increase in interferon-stimulatory gene expression in peripheral blood leukocytes. An achievable goal may be to identify markers of embryo mortality so that researchers and clinicians can focus their efforts on developing intervention strategies for cows identified to be at risk for pregnancy failure.     

利用胚挽救技术获得三倍体葡萄植株研究

对7个葡萄二倍体与四倍体杂交组合的胚珠进行离体培养研究。结果表明,多数组合在花后55d接种效果较好,胚珠萌发率较高。少数早熟品种为母本时,最佳接种时期以花后45d较好。组合不同胚珠萌发率有一定差异,其中以二倍体为母本的组合平均萌发率为22．54％,四倍体为母本的组合平均萌发率为19．64％,二倍体为母本的组合胚珠萌发率明显高于以四倍体为母本的组合。     

百合幼胚离体培养的研究

对百合败育胚离体培养的影响因素进行研究的结果表明：pH值对百合幼胚的萌发及成苗有一定的影响,以pH值5.0为最好;活性炭的浓度对其影响不明显,培养基中加入氨基酸类物质使胚萌发及成苗比率均高于对照,加入维生素类物质对胚的影响不大。     

百合幼胚离体培养基的筛选

以切花百合品种间杂交获得的胚龄为30～50d的幼胚作为外植体 ,进行离体培养基的筛选。结果表明 :基本培养基对萌发率、成苗率、生长势的影响从好到差顺序为MS>N6>SH>LS>Monnier>DCR>改良White;碳源种类对萌发的影响从好到差顺序蔗糖、甘露醇、白糖、葡萄糖、果糖 ,胚的成活情况与渗透压密切相关 ;生长素(NAA)不同浓度对幼胚成活的影响从好到差顺序为0.001>0.01>0.1>1>0,细胞分裂素(6-BA)不同浓度对幼胚成活的影响从好到差顺序为0.001>0.01>0.1>1>0。采用正交试验设计对幼胚萌发率及生长情况进行分析得出最优组合培养基为:糖60g·L-1+6 -BA0.1mg·L-1+NAA0.001mg·L-1+CH和VB6,基本培养基为MS附加琼脂10g·L-1,pH值为5.0的培养基     

小麦胚芽面包的工艺探讨

添加营养丰富的小麦胚芽研制的面包,有效地提高了面包中蛋白质、纤维素、维生素及铁、锌等营养元素含量,使主食面包的营养更加全面、合理,改善了面包的风味和口感,同时也提高了麦胚的综合利用水平。     

Theoretical Aspects of Nucleate Pool Boiling with Dielectric Liquids

Direct cooling with inert,dielectric liquids may well become the technique of choice for the thermal manage-ment of future electronic systems.Due to the efficiency of phase-change processes and the simplicity of naturalcirculation,nucleate pool boiling is of great interest for this application.This paper examines the characteristicsof vapor bubbles and nucleate pool boiling of the dielectric liquids.The results provide a theoretical foundationfor understanding and interpreting the often complex empirical results reported in the literature.