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1.
Differences in the function and composition of individual ovarian follicles were noted in Booroola Merino ewes which had previously been segregated on at least one ovulation rate record of greater than 5 (FF ewes, N = 15), 3-4 (F+ ewes, N = 18) or less than 3 (++ ewes, N = 18). Follicles in FF and F+ ewes produced oestradiol and reached maturity at a smaller diameter than in ++ ewes. In FF (N = 3), F+ (N = 3) and ++ (N = 3) ewes, the respective mean +/- s.e.m. diameters for the presumptive preovulatory follicles were 3.4 +/- 0.3, 4.1 +/- 0.2 and 6.8 +/- 0.3 mm and in each of these follicles the respective mean +/- s.e.m. numbers of granulosa cells (X 10(6)) were 1.8 +/- 0.3, 2.2 +/- 0.3 and 6.6 +/- 0.3. During a cloprostenol-induced follicular phase, the oestradiol secretion rates from FF ewes with 4.8 +/- 0.4 'oestrogenic' follicles, F+ ewes with 3.2 +/- 0.2 'oestrogenic' follicles and ++ ewes with 1.5 +/- 0.02 'oestrogenic' follicles were not significantly different from one another. Moreover, the mean total numbers of granulosa cells from the 'oestrogenic' follicles from each genotype were identical, namely 5.4 X 10(6) cells. Irrespective of genotype the mean weight of each corpus luteum was inversely correlated to the ovulation rate (R = 0.91, P less than 0.001). Collectively, these findings support the notion that the maturation of greater than or equal to 5 follicles in FF ewes and 3-4 follicles in F+ ewes may each be necessary to provide a follicular-cell mass capable of producing the same quantity of oestradiol as that from 1-2 preovulatory follicles in ++ ewes.  相似文献   
2.
Biological Trace Element Research - The essential trace elements in 30 traditional Chinese medicines, (24 tonics and 6 nontonics) were determined by proton-induced X-ray emission. The...  相似文献   
3.
露水草的光合特性及其生态学意义   总被引:2,自引:0,他引:2  
用盆栽和遮阴试验研究了露水草(Cyanotis arachnoidea Clarke) 的光合作用特征,比较了不同遮光水平对光合速率、光合器官特性及光合产量的影响。结果如下:1.露水草是一种耐阴偏阳的C3 类草木植物,其光合作用的光饱和点约为650 μm ol·m - 2·s- 1,光补偿点约为17 μm ol·m - 2·s- 1,且具有高达130×10- 6的CO2 补偿点。2.露水草的最大净光合速率为12.45 μm ol·m - 2·s- 1。叶片净光合速率的日变化规律呈双峰曲线,主峰在11~12 时,次峰在15时左右。3.遮光20% ~50% 有利于露水草的生长。与对照相比,叶片中叶绿素b 的含量增加了47% ~83% ,并且由于净光合速率(相对光合速率)的提高,使光合生产量增加了12% ~18% 。  相似文献   
4.
 以淀粉珠为载体的亲和层析法分离纯化高温α淀粉酶张学忠,宋伦,王群,吴晓霞,唐锌进(吉林大学酶工程国家重点实验室,长春130023;南京师范大学生物系,南京210024)金凤燮等人从酒曲中筛选出高产热稳定α淀粉酶的菌株,命名为Bacillussp-JF...  相似文献   
5.
玉米种子萌发成苗不同阶段需水阈值的研究   总被引:7,自引:0,他引:7  
用渗透势不同的聚乙二醇(PEG)6000模拟外界环境水分条件,对玉米不同品种的种子在萌动、萌发及成苗三个阶段需水的量化研究表明,种苗的抗旱性随吸水进程的推进而减弱;种子在萌动、萌发及胚芽伸长至一定长度的时间(t)与外界环境水势(w)之间存在着1/t=a+bw的关系,据此推算出不同品种在不同成苗阶段的需水阈值,发现不同品种在同一成苗过程中对环境水分条件的反应不同,它们的抗旱性也不同。  相似文献   
6.
宋伦  宋广军  吴金浩  杨国军  刘印  刘苏萱 《生态学报》2022,42(16):6838-6852
采用高通量测序-分子鉴定分级技术于2019年对长山群岛全海域真核微藻粒级结构进行了研究。结果发现,春季以中(47%)、小粒级(41%)为主,夏季以小(39%)、大粒级(38%)为主,秋季以大粒级(60%)为主,春、夏、秋季小、中、大粒级微藻比例为42:47:11、39:23:38、22:18:60。小粒级微藻优势种为细小微胞藻(Micromonas pusilla)、融合微胞藻(Micromonas commoda)和金牛微球藻(Ostreococcus tauri),中粒级微藻优势种为剧毒卡尔藻(Karlodinium veneficum)、大粒级微藻优势种为柔弱几内亚藻(Guinardia delicatula)、平野亚历山大藻(Alexandrium hiranoi)、多纹膝沟藻(Gonyaulax polygramma),综合整个真核微藻群落,春季由中粒径的剧毒卡尔藻占据优势(23.9%),夏季由大粒径的平野亚历山大藻占据优势(29.4%),秋季由大粒径的多纹膝沟藻占据优势(66.8%),有毒甲藻在该海域中占有绝对优势,贝毒累积风险较高,小粒径微藻中金牛微球藻和抑食金球藻曾在渤海引发褐潮,潜在威胁该海域贝类养殖业。虾夷扇贝对小粒级和大粒级微藻的选择性较低,对中粒级微藻的选择性较高,尤其对水体中优势种剧毒卡尔藻一直表现出主动选择。光学需氧量、无机氮、溶解氧、石油类及部分重金属Cd、As、Hg影响着整个长山群岛海域真核微藻粒级结构时空演变。  相似文献   
7.
ObjectivesInduced pluripotent stem cells (iPSCs) generated by monolayer cultures is plagued by low efficiencies, high levels of manipulation and operator unpredictability. We have developed a platform, reprogramming, expansion, and differentiation on Microcarriers, to solve these challenges.Materials and MethodsFive sources of human somatic cells were reprogrammed, selected, expanded and differentiated in microcarriers suspension cultures.ResultsImprovement of transduction efficiencies up to 2 times was observed. Accelerated reprogramming in microcarrier cultures was 7 days faster than monolayer, providing between 30 and 50‐fold more clones to choose from fibroblasts, peripheral blood mononuclear cells, T cells and CD34+ stem cells. This was observed to be due to an earlier induction of genes (β‐catenin, E‐cadherin and EpCAM) on day 4 versus monolayer cultures which occurred on days 14 or later. Following that, faster induction and earlier stabilization of pluripotency genes occurred during the maturation phase of reprogramming. Integrated expansion without trypsinization and efficient differentiation, without embryoid bodies formation, to the three germ‐layers, cardiomyocytes and haematopoietic stem cells were further demonstrated.ConclusionsOur method can solve the inherent problems of conventional monolayer cultures. It is highly efficient, cell dissociation free, can be operated with lower labor, and allows testing of differentiation efficiency without trypsinization and generation of embryoid bodies. It is also amenable to automation for processing more samples in a small footprint, alleviating many challenges of manual monolayer selection.

We have developed an allied protocol for reprogramming, selecting, expanding and differentiating human pluripotent stem cells on Microcarriers (designated as RepMC). This method allows faster reprogramming, selecting 30‐50‐fold more candidates for characterization and also allows us to find high quality candidates that differentiate to cardiomyocytes and blood lineages. Mechanistically, this method appears to accelerate the induction, maturation and stabilization phases of reprogramming. Our findings help simplify the process of deriving and expanding iPSCs for therapeutic applications, offering a robust and scalable suspension platform for large‐scale generation of clinical grade iPSCs.  相似文献   
8.
锦鲤4个人工雌核发育家系的微卫星标记研究   总被引:33,自引:4,他引:33  
利用Crooijmans et al.(1997)分离的包含CA重复单元的普通鲤鱼(Cyprinus carpio L.)的8个微卫星DNA标记,对从锦鲤(Cyprinus carpio L.)的红白,大正和昭和3个不同品系中所获得的4个不同人工雌核发育家系的20尾个体进行PCR扩增。电泳结果表明,8对引物在20尾个体中均能重复稳定地扩增出相应的同源序列。随引物不同,各等位基因数为1-11个,大小在68-264bp。在MFW4,MFW7,MFW19,MFW20,MFW23和MFW24 6个微卫星的扩增结果中,20尾个体的扩增图谱呈现了高度的遗传多态性,不同雌核发育家系内个体的遗传异质性也较大。其中大正(TaS)和红白1(RW1)的个体不仅花色分化显著,而且个体间的平均遗传距离分别高达0.28。通过对微卫星等位基因和基因型分析发现,由于锦鲤品系中的每一个体是通过不断地杂交选育而获得,基因组来源复杂,基因高度杂合。因此,只进行1代的人工雌核发育,其家系内仅部分个体的部分座位出现纯合。所获得的人工雌核发育锦鲤为后续的色素遗传调控机制研究提供了必要的实验材料;同时,所鉴定的微卫星分子标记为进行锦鲤的分子标记育种的基因组作图提供了理想的工具。  相似文献   
9.
Arsenite (As(III)), an effective chemotherapeutic agent for the acute promyelocytic leukemia (APL) and multiple myeloma (MM), might be also a promise for the therapy of other cancers, including the solid tumors. However, the molecular bases of arsenite‐induced cytotoxicity in the tumor cells have not been fully defined. In this study, we have disclosed that arsenite effectively induces the apoptotic response in the HepG2 human hepatoma cells by triggering GADD45α induction and the subsequent activation of JNKs/AP‐1 cell death pathway. However, signaling events relating to GADD45α/JNKs/AP‐1 pathway activation have not been observed in HL7702 human diploid hepatic cells under the same arsenite exposure condition. Our results thus have illustrated the selective pro‐apoptotic role of arsenite in the hepatoma cells by activating GADD45α‐dependent cell death pathway whereas with little effect on the normal hepatic cells. The approaches to up‐regulate GADD45α levels might be helpful in improving the chemotherapeutic action of arsenite on certain solid tumors including hepatoma. J. Cell. Biochem. 109: 1264–1273, 2010. © 2010 Wiley‐Liss, Inc.  相似文献   
10.
桔青毒素(citrinin,CTN)是以玉米、谷物、奶酪等为主要成分的食品和动物饲料中常见的、由桔青霉菌产生的酮类真菌毒素,可引起人和动物的慢性中毒或癌症,一直缺少灵敏的快速检测方法。本文通过指数富集适体系统进化技术(简称SELEX)对可能与CTN结合的特异性适体进行了筛选,经过15轮循环,得到17条适体。通过二级结构分析、亲和力检测发现适体13(Apt-13)对CTN有较好的亲和度,解离常数Kd为0.06μmol/L。进一步利用非荧光标记染料PicoGreen,利用其与双链DNA结合的原理,建立了桔青毒素非标记荧光检测方法,30min完成检测,最低检测限达到国家标准(50ppb)且与其他毒素无交叉反应。本研究建立的基于适体的桔青毒素检测技术成本低,可以替代传统的基于抗体的检测方法,为霉菌毒素的精准检测技术的开发提供了实验证据。  相似文献   
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