Seeing more clearly: recent advances in understanding retinal circuitry     

He S  Dong W  Deng Q  Weng S  Sun W 《Science (New York, N.Y.)》2003,302(5644):408-411

Among 10 breakthroughs that Science announced at the end of 2002 was the discovery of a photosensing (melanopsin-containing) retinal ganglion cell (RGC) and its role in entraining the circadian clock. This breakthrough exemplifies the ultimate goal of neuroscience: to understand the nervous system from molecules to behavior. Light-sensing RGCs constitute one of a dozen discrete RGC populations coding various aspects of visual scenes by virtue of their unique morphology, physiology, and coverage of the retina. Interestingly, the function of the melanopsin-containing RGCs in entraining the circadian clock need not involve much retinal processing, making it the simplest form of processing in the retina. This review focuses on recent advances in our understanding of retinal circuitry, visual processing, and retinal development demonstrated by innovative experimental techniques. It also discusses the advantages of using the retina as a model system to address some of the key questions in neuroscience.  相似文献   

《道德经》之一分为三哲学思想研究     

周德义 《湖南农业大学学报(自然科学版)》2003,(5)

在《道德经》中 ,老子运用一分为三的思维方式 ,围绕着“道”这一中心概念的逐步展开 ,构建了充满着辩证法的哲学体系 ,成为中华文化的奇丽瑰宝。论述了“道”为“一”、为“无”、为“无为”、为“自然”的一分为三的哲学内涵 ;“自然”为老子哲学体系的开端 ;“道”的“万物得一以生”、“反者道之动”、“物壮则老”、凡事“守中”的一分为三的作用和意义 ;求“道”的一分为三的过程 ;并以此讨论宇宙的起源 ,世界的形成 ,事物的产生、变化和发展的规律 ,以及人类社会的种种矛盾及其解决的方式 ;还讨论了黑格尔对老子一分为  相似文献   

Non-steroidal anti-inflammatory drugs induce apoptosis in implanted hepatoma of mice     

WU Wei-jiang  LI Xiao-hong  REN Xian-da  LUO Yu-hong  ZHOU Qi-jing  LIANG Xiao-yu 《园艺学报》2003,19(8):1074-1078

AIM: To study the mechanism of the effect of NSAIDs on apoptosis in mice hepatoma at anti-inflammatory doses. METHODS: Kunming breed mice were inoculated subcutaneously in the flank with mice hepatoma H22 cell line. The effects of ibuprofen, indomethacin, and nimesulide on apoptosis were determined by using electron microscopy, agarose gel electrophoresis, flow cytometry, and Western blot analysis of the expression of c-myc, bcl-x_L and bcl-2 proteins. RESULTS: NSAIDs induced apoptosis of mice implanted hepatoma, which includes the morphological changes such as reduction in the volume, and the nuclear chromatin condensation, as well as the "ladder pattern" revealed by agarose gel electrophoresis of DNA. The apoptotic index was increased to 15%±1.0%, 29.7%±1.5%, 46.3%±3.5% from 3.3%±0.6% by detecting Sub-G₁ peaks on flow cytometry. Western blot analysis showed that levels of bcl-2 and bcl-x_L were significantly reduced by treatment with nimesulide. Ibuprofen and indomethacin decreased bcl-2 expression but increased bcl-x_L expression. C-myc wasn't changed in these groups. CONCLUSION: These results suggest that NSAIDs induces apoptosis of mice hepatoma, which may be due to their regulation on the expressions of bcl-2 family genes.  相似文献   

Scale dependence of tree abundance and richness in a tropical rain forest,Malaysia   总被引：5，自引：0，他引：5  

He  Fangliang  LaFrankie  James V.  Song  Bo 《Landscape Ecology》2002,17(6):559-568

Abundance and richness are the two fundamental components of speciesdiversity. They represent two distinct types of variables of which the formerisadditive when aggregated across scales while the latter is nonadditive. Thisstudy investigated the changes in the spatial patterns of abundance andrichnessof tree species across multiple scales in a tropical rain forest of Malaysiaandtheir variations in different regions of the study area. The results showedthatfrom fine to coarse scales abundance had a gradual and systematic change inpattern, whereas the change in richness was much less predictable and ahotspot in richness at one scale may become acoldspot at another. The study also demonstrated that differentmeasures of diversity variation (e.g., variance and coefficient of variation)can result in different or even contradictory results which further complicatedthe interpretation of diversity patterns. Because of scale effect the commonlyused measure of species diversity in terms of unit area (e.g.,species/m²) is misleading and of little use in comparing speciesdiversitybetween different ecosystems. Extra care must be taken if management andconservation of species diversity have to be based on information gathered at asingle scale.This revised version was published online in May 2005 with corrections to the Cover Date.  相似文献   

山羊卵巢无腔卵泡的体外发育   总被引：4，自引：0，他引：4  

周欢敏  张涌 《中国畜牧杂志》2000,36(2):12-14

在三维琼脂凝胶培养体系中 ,山羊无腔卵泡的生长模式类似于体内。在一定培养时间内能善为保持其完整的立体结构和形态。原始卵泡能在体外启动 ,并得到一定程度的生长。初级卵泡能发育为次级卵泡 ,次级卵泡发育为有腔卵泡。卵泡在体外发育过程中 ,表现出了明显的优势化。本试验首次初步揭示了山羊无腔卵泡的体外发育基本过程和规律。  相似文献   

黄皮种子脱水敏感性与核酸、蛋白质代谢的关系   总被引：3，自引：0，他引：3  

王艳  李韶山  何军贤  傅家瑞 《园艺学报》2000,27(3):210-210

黄皮种子发育晚期,胚内核酸和蛋白质合成能力增强,而花生种子发育晚期则呈下降趋势。脱水处理使生理成熟期黄皮胚核酸和蛋白质合成能力急剧下降,核酸水解酶活性增强。生物大分子代谢能力的变化是黄皮种子脱水敏感性的分子基础。  相似文献   

用RAPD标记研究7个猪种间的亲缘关系   总被引：5，自引：0，他引：5  

赵凯  张周平  杨公社  周继平  魏雅萍  仇桂芳 《黑龙江畜牧兽医》2000,199(7):1-3

试验利用随机扩增多态ＤＮＡ技术对互助猪、荣昌猪、甘肃白猪、长白猪、约克夏猪、杜洛克猪、汉普猪共７个品种的ＤＮＡ池进行了多态型研究,分析了各品种间的亲缘关系。结果显示：甘肃白猪虽然是由国外品种和地方品种培育而成,但其亲缘关系更接近于中国猪品种;约克夏猪与其它欧洲猪种亲缘关系较远,这可能与约克夏猪在培养过程中亲本遗传背景较为复杂有关。  相似文献   

高寒牧区陶赛特绵羊鲜胚移植试验观察     

雷有鹏  马增义  何成基  祁文珍  朱俊  孔祥颖 《中国草食动物》2007,27(6):36-37

选取兰州信合牧业34只陶赛特绵羊为供体，采用递减法注射FSH进行超排，采用人工授精配种，30只长途运输到青海省海北州西海镇手术法回收胚胎，鉴定后移值。155只藏系绵羊作为受体，采用两次PG注射进行同期发情，119只受体在西海镇移植，32只长途运输到甘肃兰州信合牧业进行移植。结果表明：34只供体获得胚胎共168枚，每只供体平均获得4．94枚，合格率89．88％，151只受体表现发情，发情率为97．42％。其中．在西海镇移植的119只产羔73只，产羔率为61．34％，在兰州移植的32只产羔21只，产羔率为65．6％。  相似文献   

虎纹捕鸟蛛毒素提取的研究   总被引：1，自引：0，他引：1  

潘红平  周放  刘岱岳  蒙健宗  陆凤花  杨素芳  王晓丽 《经济动物学报》2007,11(2):105-107

为探索提取广西产虎纹捕鸟蛛(Selenocosmia huwena)毒素的新方法,选取雌性虎纹捕鸟蛛225只,根据提取方法(直接咬软管法、直接咬瓶法、激怒咬渐法激怒咬瓶冲洗法)分为4组,结果表明,采用直接咬软管法提取虎纹捕鸟蛛毒素,平均每只蜘蛛可以获得冻干毒素2.28 mg,与采用直接咬瓶法所获得的2.19 mg没有显著差异(P>0.05)。采用激怒咬瓶冲洗法提取虎纹捕鸟蛛毒素,平均每只蜘蛛可以获得冻干毒素重量明显高于激怒咬瓶法[(3.41±0.40)mg,(2.99±0.35)mg,P<0.05],亦明显高于直接咬软管法和直接咬瓶法。该试验结果表明,激怒咬瓶冲洗法是一种提取虎纹捕鸟蛛毒素的有效方法。  相似文献   

喷雾干燥鱼浆蛋白粉营养成分分析     

陈宜芳  何瑞国  任泽林  程一兵 《中国饲料》2007,(6):32-33

本试验对鱼粉加工废水鱼浆蛋白粉(经浓缩、水解、喷雾干燥得到的副产品)进行营养成分分析,其中粗蛋白质含量达64.08%,钙2.67%、磷1.12%,钙磷比例合理;各氨基酸含量分别为:赖氨酸3.29%,蛋氨酸0.94%,谷氨酸5.17%,牛磺酸2.50%。  相似文献