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801.
蒋芝华  吕建利 《生理学报》1995,47(3):281-286
将胎龄为17d的大鼠胚胎海马(移植物)移植到同种成年大鼠(宿主)腹海马,90d后,用TH免疫细胞化学方法对海马移植物内神经元与儿茶酚胺(catecholamine CA)能纤维之间的突触联系进行上观察。免疫组织化学显示,宿主海马内有大量TH免疫反应纤维。这些纤维是直径为0.5-1μm的细纤维。它们的分布密度是,齿回门区和CA3区透明层内较密集,分子层次之,锥体细胞层和颗粒细胞层内较稀疏。在移植物的  相似文献   
802.
Formaldehyde (HCHO) is suggested to be detoxified through one‐carbon (C1) metabolism or assimilated by the Calvin cycle in plants. To further understand the function of the Calvin cycle and C1 metabolism in HCHO metabolism in plants, HCHO elimination and metabolism by Arabidopsis thaliana in HCHO solutions was investigated in this study. Results verified that Arabidopsis could completely eliminate aqueous HCHO from the HCHO solutions. Carbon‐13 nuclear magnetic resonance (13C‐NMR) analysis showed that H13CHO absorbed by Arabidopsis was first oxidized to H13COOH. Subsequently, a clear increase in [U‐13C]Gluc peaks accompanied by a strong enhancement in peaks of [2‐13C]Ser and [3‐13C]Ser appeared in Arabidopsis. Pretreatment with cyclosporin A or L‐carnitine, which might inhibit the transport of 13C‐enriched compounds into chloroplasts and mitochondria, caused a remarkable decline in yields of both [U‐13C]Gluc and [3‐13C]Ser in H13CHO‐treated Arabidopsis. These results suggested that both the Calvin cycle and the C1 metabolism functioned simultaneously during HCHO detoxification. Moreover, both functioned more quickly under high H13CHO stress than low H13CHO stress. When a photorespiration mutant was treated in 6 mm H13CHO solution, formation of [U‐13C]Gluc and [2‐13C]Ser was completely inhibited, but generation of [3‐13C]Ser was not significantly affected. This evidence suggested that the Calvin cycle and C1 metabolism functioned independently in Arabidopsis during HCHO metabolism.  相似文献   
803.
结直肠癌是一种涉及遗传、环境和生活方式等多风险因素的疾病。越来越多的研究表明肠道菌群在结直肠癌的发生发展中起重要作用,菌群与消化道之间的共生作用对维持肠道内环境的稳定也十分重要。菌群在炎症、药物代谢,甚至癌症的发展中扮演着许多角色,然而由感染、饮食或生活方式等变化引起的菌群组成的改变却可影响这种共生关系。同样,菌群组成的变化使部分菌种在肠内引发炎症反应甚至致癌,从而对结肠直肠癌的发生发展产生实质性的影响,综述将总结目前肠道菌群与结直肠癌之间潜在的联系,重点关注细菌在肠道中所参与的各种反应,从而为治疗结直肠癌提供更多的研究思路。  相似文献   
804.
A new subfamily of Praesiricidae (Pamphilioidea), Decorisiricinae subfam.n. , is erected based on three new genera: Decorisiricius gen.n. , Limbisiricius gen.n. and Brevisiricius gen.n. Two new species – Decorisiricius patulus gen. et sp.n. and D. longus sp.n. – from the Lower Cretaceous Yixian Formation and three species –Limbisiricius aequalis gen. et sp.n. , Limbisiricius complanatus sp.n. and Brevisiricius partialis gen. et sp.n. – from the Middle Jurassic Jiulongshan Formation, are described. Based on these well‐preserved new fossil specimens and previously published data, the nonmonophyly of Praesiricidae is confirmed and the phylogenetic relationships of species of Praesiricidae are analysed for the first time. Two main clades within Praesiricidae are recognized from the cladistic analysis: Decorisiricinae subfam.n. forms a monophyletic lineage, with the remaining members of Praesiricidae plus Megalodontes (Megalodontesidae) forming its sister group. The two subfamilies Archoxyelydinae and Praesiricinae are discarded with no strong supported synapomorphic characters based on phylogenetic research. A key to all genera of Praesiricidae is provided. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:38D703ED‐127A‐4DB0‐8153‐8D78AF4AC212 .  相似文献   
805.
806.
1. Due to climate change, contemporary climate scenarios forecast an increase in extreme weather, which may have considerable impacts on the world's riverine ecosystems. Because the flow regime is a primary determinant of the structure and function of lotic ecosystems, changes in the weather could fundamentally alter these ecosystems through changes in hydrologic disturbance regimes. 2. In this paper, we use the abundance/biomass comparison (ABC) method, based on r/K selection theory, and event probability distribution to characterise the responses of macroinvertebrates in Taiwan mountain streams to extreme floods. 3. Severe impacts on macroinvertebrates, resulting in a large shift in community structure toward r‐selected taxa, usually were observed the year after extreme floods. 4. Macroinvertebrate communities dominated by K‐selected taxa had more individuals with traits conferring resistance to flooding disturbance, while those dominated byr‐selected taxa had more individuals with traits conferring resilience. 5. This relationship between the changes in flow regime and the ecological response of r‐ and K‐selected taxa may be exploited to understand the potential effects of flood extremes in the future, and to keep decision makers informed about the ecological consequences of climate‐mediated changes to hydrological regimes.  相似文献   
807.
INTRODUCTION7-aminobutyricacid(GABA)isthemajorinhibitoryneurotransmitterinthevertebratecelltralnervoussystemwhereitactingesavaxietyofGABAreceptortypes.TheneurotransmissionofGABAisthoughttobeterllilnatedbyit'srapidre-uptakeviaGABAtransportersintopresynapticneuronsandsurroundingglialcellsll,2].BesidesfUnctioningintheterminationofsynaptictransmission,GABAtransportersplayacriticalroleintheregUlationofthemagnitudeanddurationofGABA'sactionandmayajsomediatethereleaseofGABAintotheedrac…  相似文献   
808.
学习记忆对脑内c-fos基因表达的影响   总被引:11,自引:0,他引:11  
张玉秋  梅俊 《生命科学》2000,12(5):228-230,216
学习记忆是人和动物重要的脑功能,大量事实表明,学习记忆过程与脑内c-fos基因的表达密切相关。由学习记忆所诱导的c-fos基因表达在脑内广泛分布,以皮层、海马和边缘系统为多,依学习记忆训练模型的不同,其表达时程有所差异,但一般于训练后立即或30分钟左右出现,1~2小时左右达峰值。被动和主动回避训练、光辨别训练及味觉厌恶性条件反射训练等多种学习记忆模型均可诱导脑内c-fos基因的表达。其他影响学习记  相似文献   
809.
训练两只猕猴进行延缓GO/NO-GO任务操作。猴坐在定制的猴椅中,正前方40cm处放着计算机显示器。显示器下方装有一压板。猴按压板0.5s后,显示器屏幕右下角或左下角出现一白色方块信号(1.5cm×1.5cm),持续0.5s。这一信号为暗示信号。暗示信号消失后,延缓0.0-4.0s,然后在显示器屏幕的下方正中处出现一红色方块信号(1.5cm×1.5cm)。这一信号为反应信号。如果暗示信号出现在右边,则要求猴在0.8s内放开一直按着的压板(GO反应);如果暗示信号出现在左边,则要求猴继续按住压板1.2s(NO-GO反应)。正确操作后,猴得到一滴水的奖励。在这一行为任务中,延缓期内的短时工作记忆是“非空间表象”(non-spatiallyrepresentatioal)短时工作记忆。前额叶皮层背外侧部(Walket46区、9区)内注射α2受体拮抗剂yohimbine(10μg/2μl)使猴的任务操作正确率下降。延缓期越长,下降的幅度越大。注射Yohimbine后,猴的操作错误率升高主要表现在“交叉”反应率升高,即应该作GO反应时作NO-GO反应,反之亦然。注射α1受体桔抗剂Prazosin(10μg/2μl)或  相似文献   
810.
在已有赤潮理论的基础上,利用细胞接触的抑制作用建立了一个赤潮生物种群的控制模型.根据变结构控制原理,设计变结构控制器,使控制模型在有害藻灭绝时的平衡点处稳定.最后用数值仿真验证所得结果的正确性.  相似文献   
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