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本实验的主要目的旨在摸索电场对基因转化的最佳条件.已得到初步结果为:用酿酒酵母S.cerevisiae DBY 746作为穿梭质粒(YRp类)的受体菌.经过对最适电场条件与基因转化率之间关系的研究,我们发现在1个400μS的宽时程脉冲、电场强度为4KV/cm时有最高转化率,达273个转化子/μgDNA.本实验所用的电穿孔装置是自组装的,它简便、快速、实用. 相似文献
74.
大红袍中单宁化学成分的研究 总被引:1,自引:0,他引:1
从大红袍中分离出5个单宁化合物,通过光谱分析确定其结构分别为:epicatechin(?),procyanidin B-1(?),procyanidin B-2(?),procyanidin B-5(4)和 procyanidin C-1(5).上述化合物均为首次从该植物中分离得到。 相似文献
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Four experiments were conducted to study 1) factors affecting porcine oocyte maturation in culture medium and 2) a new method for oocyte maturation outside the porcine body. In Experiment 1, five groups of oocytes were cultured in m-TCM199 or m-KRB medium for 24 to 28, 32 to 36 or 40 to 42 hours and then were fertilized in vitro. The cleavage rate (two to four-cell stage) of oocytes cultured for 32 to 36 hours was significantly higher than those of the other oocytes. The results indicate that a suitable culture period for the in vitro maturation of porcine oocytes is 32 to 36 hours. In Experiment 2, four groups of oocytes were cultured in m-KRB or m-KRB supplemented with PFF, PMSG or FSH for in vitro maturation, and the cleavage rates of oocytes were 7.94, 22.56, 30.23 and 23.26%, respectively, after in vitro fertilization. The results show that porcine follicular fluid (PFF) and gonadotrophins added to the culture medium promote porcine oocyte maturation in vitro. In Experiment 3, oocytes were cultured in m-KRB or m-TCM199, supplemented with both gonadotrophin and pocine folliclar fluid for maturation in vitro. After fertilization in vitro, the cleavage rates of oocytes were 26.32 and 27.93% for the two media. The results indicate that the difference between m-KRB and m-TCM199 was insignificant when the media were used to culture porcine oocytes. But there was a significant difference when PFF and gonadotrophins were added to the basic media. In Experiment 4, porcine oocytes were transferred into the reproductive tracts of other animals for maturation. After 34 to 36 hours, the oocytes were collected and fertilized in vitro. The cleavage rates of oocytes were 10.42, 28.45, 3.33 and 36.36%, respectively, for the oocytes matured in mouse uterine horns, rat uterine horns, rat oviducts or rabbit oviducts. The results show that porcine oocytes can be matured in the reproductive tracts of other animals. 相似文献
78.
Quantitative cell composition of human and bovine corpora lutea from various reproductive states 总被引:7,自引:0,他引:7
The cell composition of human and bovine corpora lutea (CL) from various reproductive states was investigated by computerized video-based interactive Bioquant image analysis system IV and by light microscope immunocytochemistry. Human and bovine CL contained more nonluteal cells than luteal cells. Human CL contained a lower number of luteal and a greater number of nonluteal cells than bovine CL. Regardless of the reproductive state, human CL contained more small luteal cells than large luteal cells. In all reproductive states except in the late luteal phase, the bovine CL also contained more small luteal cells than large luteal cells. The average sizes of all the cells in human CL were smaller than in bovine CL. Human CL contained more vascular space than bovine CL during mid and late luteal phases. The number of luteal cells increased and nonluteal cells decreased from early to mid luteal phase, and then luteal cells decreased and nonluteal cells increased in late luteal phase and in degenerating human and bovine CL. While the change of number of small and large luteal cells first occurred from early to mid luteal phase in human CL, it did not take place until the late luteal phase in bovine CL. The average size of large luteal cells in humans and of small luteal cells in cattle did not change, whereas size of the other cells changed in different reproductive states in both human and bovine CL. The cell composition of term pregnancy human CL was similar to mid or late luteal phase, whereas the cell composition of early pregnancy bovine CL was similar to mid luteal phase.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
79.
Immunocytochemical localization of relaxin in human corpora lutea: cellular and subcellular distribution and dependence on reproductive state 总被引:1,自引:0,他引:1
E Stoelk N Chegini Z M Lei C V Rao G Bryant-Greenwood J Sanfilippo 《Biology of reproduction》1991,44(6):1140-1147
Relaxin is one of the hormones present during pregnancy and it is synthesized primarily by corpora lutea (CL). Other reproductive tissues including CL of the menstrual cycle may also synthesize this hormone. Very little is known, however, about the cellular and subcellular distribution of relaxin in human CL and dependence of luteal relaxin on the reproductive state. The light and electron microscope immunocytochemical studies described here were undertaken to obtain this information using antisera to porcine and human relaxin. Immunostaining was found in large luteal cells (17-30 microns) but not in small luteal cells (7-16 microns) or in nonluteal cells in any of the reproductive states or in human hepatocytes. Luteal immunostaining was low in early luteal phase; it increased progressively, reaching the highest level in late luteal phase, and then decreased greatly in corpora albicantia. Term pregnancy CL contained similar immunostaining as early luteal phase CL. Mid luteal phase CL contained more immunostained cells than late luteal phase CL, but the late luteal phase CL contained a greater amount of immunostaining per cell than mid luteal phase CL. The immunogold particles due to relaxin were primarily present in secretory granules and to a small extent in rough endoplasmic reticulum. Quantitation revealed that secretory granules contained a much higher number of gold particles than did rough endoplasmic reticulum. These two organelles from late luteal phase CL contained greater numbers of gold particles than those from mid luteal phase.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
80.
中国陆地生态系统碳源/汇整合分析 总被引:4,自引:0,他引:4
国家尺度陆地生态系统碳收支及其循环过程的研究对于提升地球系统科学与全球变化科学的科技创新能力、提高我国参与应对全球气候变化国际行动和维护国家利益的话语权、保障国家生态安全和改进生态系统管理都具有重要意义。近年来,我国已经在气候变化与陆地生态系统碳循环领域开展了大量的研究工作,主要包括国家清查、生态系统模型模拟、大气反演等手段。然而,由于大尺度陆地生态系统碳源/汇的估算存在很大的不确定性,目前尚未形成国家尺度的陆地生态系统碳源/汇的整合分析。通过搜集已发表的关于中国陆地生态系统及其组分碳源/汇的59篇文献,整合国家清查、生态系统模型模拟、大气反演3种研究手段,分析中国陆地生态系统碳源/汇大小以及时间尺度上的动态变化。结果表明,在1960s-2010s期间中国陆地生态系统碳汇整体呈上升趋势,平均为(0.213±0.030)Pg C/a,其中森林、草地、农田和灌木生态系统碳汇分别为(0.101±0.023)Pg C/a、(0.032±0.007)Pg C/a、(0.043±0.010)Pg C/a和(0.028±0.010)Pg C/a。森林生态系统中的植被碳汇远大于土壤碳汇,然而这种格局在草地和农田生态系统却相反,而且1960s-2010s期间中国主要植被类型的生态系统碳汇总体上随时间呈增加趋势。融合多源数据(地面观测、激光雷达、卫星遥感等)、多尺度数据(样地尺度、站点尺度、区域尺度)以及多手段数据(联网观测、森林清查、模型模拟),有助于全面准确地评估中国陆地生态系统碳源/汇及其对气候变化的响应。 相似文献