Differential pattern of spinal sympathetic outflow in response to stimulation of the caudal medullary raphe

In urethan-anesthetized cats, frequency domain analysis was used to explore the mechanisms of differential responses of inferior cardiac (CN), vertebral (VN), and renal (RN) sympathetic nerves to electrical stimulation of a discrete region of the medullary raphe (0-2 mm caudal to the obex). Raphe stimulation in baroreceptor-denervated cats at frequencies (7-12 Hz) that entrained the 10-Hz rhythm in nerve activity decreased CN and RN activities but increased VN activity. The reductions in CN and RN discharges were associated with decreased low-frequency (相似文献   

假单胞菌L-半胱氨酸合成酶的纯化和性质研究

假单胞菌TS-1138的细胞浆液通过硫铵沉淀、SephadexG-75凝胶过滤、DEAE-Cellulose52离子交换、SephadexG 100凝胶过滤等分离纯化手段分别将从L-ATC合成L 半胱氨酸的两个酶——L-ATC水解酶和L-SCC水解酶纯化了 83.9和 90.3倍。SDS-PAGE鉴定均为单一条带 ,两种酶的相对分子质量分别为 37.5和 42.8kD ;酶反应的最适温度均为 35℃ ,最适pH分别为 7.0和 8.0 ;酶的米氏常数分别为 0.67mmol L和 0.15mmol L ,     

中国科学院内蒙古草原生态系统定位站学术交流会在京召开

中国科学院内蒙古草原生态系统定位站学术交流会已于1981年1月29日至2月3日在北京召开。参加这次会议的有中国科学院植物研究所、动物研究所、综合考察委员会及内蒙古大学等17个单位,42人。     

Hydroxyethylamine-based inhibitors of BACE1: P1–P3 macrocyclization can improve potency,selectivity, and cell activity

We describe a systematic study of how macrocyclization in the P₁–P₃ region of hydroxyethylamine-based inhibitors of β-site amyloid precursor protein (APP)-cleaving enzyme (BACE1) modulates in vitro activity. This study reveals that in a number of instances macrocyclization of bis-terminal dienes leads to improved potency toward BACE1 and selectivity against cathepsin D (CatD), as well as greater amyloid β-peptide (Aβ)-lowering activity in HEK293T cells stably expressing APP_SW. However, for several closely related analogs the benefits of macrocyclization are attenuated by the effects of other structural features in different regions of the molecules. X-ray crystal structures of three of these novel macrocyclic inhibitors bound to BACE1 revealed their binding conformations and interactions with the enzyme.     

Highly sensitive determination of the methylated p16 gene in cancer patients by microchip electrophoresis

The p16 tumor suppressor gene is inactivated by promoter region hypermethylation in many types of tumor. Recent studies showed that aberrant methylation of the p16 gene is an early event in many tumors, especially in lung cancer, and may constitute a new biomarker for early detection and monitoring of prevention trials. We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma and tissue DNA from 153 specimens using a modified semi-nested methylation-specific PCR (MSP) combining plastic microchip electrophoresis or slab gel electrophoresis, respectively. Specimens were from 79 lung cancer patients, 15 abdominal tumor patients, 30 positive controls and 30 negative controls. The results showed that the positive rate obtained by microchip electrophoresis was more than 26.6% higher and the same specificity was kept when compared with slab gel electrophoresis. The microchip electrophoresis can rapidly and accurately analyze the PCR products of methylated DNA and obviously improve the positive rate of diagnosis of cancer patients when compared with gel electrophoresis. This method with the high assay sensitivity might be used for detection of methylation of p16 gene and even to facilitate early diagnosis of cancer patients.     

A comprehensive gene network for fine tuning floral development in poplar

Herbaceous model species, especially Arabidopsis has provided a wealth of information about the genes involved in floral induction and development of inflorescences and flowers. While the genus Populus is an important model system for the molecular biology of woody plant. These two genuses differ in many ways. This study was designed to improve understanding of flower development in poplar at a system level, as its regulatory pathway to a large extent remains poorly known, owing to the presently limited mutant pool. To address this issue, a poplar GeneChip was employed to detect genes expressed during the whole floral developmental process. Using the expressed floral genes, a systematic gene network was constructed with the aid of functional association with Arabidopsis. The results suggested that autonomous, gibberellin, vernalization, photoperiod, ethylene, brassinosteroid, stress-induced and floral suppression pathways are involved in poplar flowering. Modularity analysis revealed several pathways in common with Arabidopsis, such as autonomous, gibberellin, vernalization and photoperiod pathways. In addition, brassinosteroid, stress-induced and floral suppression pathways were implicated as additional novel pathways. Notably, a difference in vernalization between Arabidopsis and poplar was revealed. Autonomous, gibberellin, vernalization, photoperiod, ethylene, brassinosteroid, stress-induced and floral suppression pathways integrated into a systematic gene network in floral development of poplar. Compared to Arabidopsis, brassinosteroid, stress-induced and floral suppression pathways are additional in poplar, and FLC is absent in vernalization pathway in poplar. Preliminary conclusions drawn here provide a basis for both identification of key genes and elucidation of molecular mechanisms involved in poplar floral development.     

用RAPD技术鉴定小麦属间不对称体细胞杂种

用随机引物扩增多态DNA(RAPD)技术对三种不同组合:小麦(Triticum aestivum)( )簇毛麦(Haynaldia villosa);小麦( )羊草(Leymus chinensis)和小麦( )高冰草(Agropyron elongatum)的属间不对称杂种进行分子鉴定,不同杂种植株的基因组经随机引物扩增后,均出现双亲的多态特异产物,证实它们含有双亲的基因组。将引物OPJ-12扩增的高冰草多态特异产物(分子量为0.77bp的DNA片段)分离纯化并标记作探针,用Southern杂交证明了小麦( )高冰草杂种经OPJ-12扩增的0.77kbp特异片段与高冰草这一片段具有同源性。本文结果证明,RAPD技术可作为小麦属间不对称体细胞杂种的一种快速、简便、有效的分子鉴定方法。     

长白山白眉蝮蛇蛇毒磷脂酶A2的分离和初步表征

东北长白山白眉蝮蛇（ＡｇｋｉｓｔｒｏｄｏｎｂｌｏｍｈｏｆｆｉＵｓｕｒｅｎｓｉｓ）蛇毒经ＤＥＡＥＳｅｐｈａｄｅｘＡ５０离子交换层析柱,连续３步ＳｅｐｈａｄｅｘＧ７５凝胶过滤柱得到了磷脂酶Ａ２（ＰＬＡ２）的纯品。ＳＤＳ聚丙烯酰胺凝胶电泳（ＳＤＳＰＡＧＥ）以及基质辅助激光解析电离飞行时质谱（ＭＡＬＤＩ／ＴＯＦ／ＭＳ）表征为单一蛋白,其准确分子量为（１４．００８±０．００７）ｋＤ。最适ｐＨ范围８．０～９．０,最适的反应温度为４５℃。在溶液中有多聚体的存在。