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111.
七种云南地衣植物的化学成分 总被引:12,自引:1,他引:12
本文报道分属于三个科的七种云南产地衣植物的化学成分。这些植物是亚洲树发(Alectoria asiatica DR.)、沟树发(Alectoria sulcata Nyl.)、长茎松萝(Usnea longissimaAch.)、胡子松萝(Usnea comosa(Ach.)Rohl.)、林石蕊(Cladonia arbuscula(Rabh.)Rabh.)、砖孢发(Oropogon loxensis(Fee.)Th.Fr.)和卷梢雪花衣(Anaptychiaboryi(Fee.)Mass.)。根据光谱数据测定,其化学成分为:松萝酸(Usnic acid)(1),维任西酸(Virensic acid)(2),赤星衣酸乙酯(Ethyl haematommate)(3),瑞藏酸(Rhizonic acid)(4),赤星衣酸(Haematommic acid)(5),扁枝衣酸乙酯(Ethyleverninate)(6),黑茶渍素(Atranorin)(7)和泽屋萜(Zeorin)(8)。上述资料,对开发利用这些植物资源提供了科学依据。 相似文献
112.
Cheng Du Baosheng Ge Zhongfeng Liu Kai Fu Wing C Chan Timothy W McKeithan 《BMC biotechnology》2006,6(1):28-11
Background
The use of small interfering RNAs (siRNAs) to silence target gene expression has greatly facilitated mammalian genetic analysis by generating loss-of-function mutants. In recent years, high-throughput, genome-wide screening of siRNA libraries has emerged as a viable approach. Two different methods have been used to generate short hairpin RNA (shRNA) libraries; one is to use chemically synthesized oligonucleotides, and the other is to convert complementary DNAs (cDNAs) into shRNA cassettes enzymatically. The high cost of chemical synthesis and the low efficiency of the enzymatic approach have hampered the widespread use of screening with shRNA libraries. 相似文献113.
HuYJ ZangL 《Cell research》2001,11(4):293-300
INTRODUCTIONThe CD4 T cells can be subdivided intoTh1 and Th2 subsets based on their secreted cy-tokine profile. Th1 cells characteristical1y secreteInterferonry (IFN--ry), whereas Th2 cells maiuly pro--duce IL--4[1]. IL-12 po1arizes the differentiation ofnaitre, CD4 T cells towards Th1 pathWay, in con-trast IL--4 directs T cell differentiation towards Th2pathWay The broken balance between Th1 and Th2immune responses and predominant Th1 responseare crucial factors in initiation… 相似文献
114.
Karagiannides I Tchkonia T Dobson DE Steppan CM Cummins P Chan G Salvatori K Hadzopoulou-Cladaras M Kirkland JL 《American journal of physiology. Regulatory, integrative and comparative physiology》2001,280(6):R1772-R1780
Fat mass, adipocyte size and metabolic responsiveness, and preadipocyte differentiation decrease between middle and old age. We show that expression of CCAAT/enhancer binding protein (C/EBP)-alpha, a key regulator of adipogenesis and fat cell function, declined substantially with aging in differentiating preadipocytes cultured under identical conditions from rats of various ages. Overexpression of C/EBP alpha in preadipocytes cultured from old rats restored capacity to differentiate into fat cells, indicating that downstream differentiation-dependent genes maintain responsiveness to regulators of adipogenesis. C/EBP alpha-expression also decreased with age in fat tissue from three different depots and in isolated fat cells. The overall level of C/EBP beta, which modulates C/EBP alpha-expression, did not change with age, but the truncated, dominant-negative C/EBP beta-liver inhibitory protein (LIP) isoform increased in cultured preadipocytes and isolated fat cells. Overexpression of C/EBP beta-LIP in preadipocytes from young rats impaired adipogenesis. C/EBP delta, which acts with full-length C/EBP beta to enhance adipogenesis, decreased with age. Thus processes intrinsic to adipose cells involving changes in C/EBP family members contribute to impaired adipogenesis and altered fat tissue function with aging. These effects are potentially reversible. 相似文献
115.
Like phosphorylation, protein sumoylation likely represents a dynamic PTM to alter protein function in support of cell regulatory systems. The broad-spectrum impact of transient or chronic engagement of signal transduction cascades on protein sumoylation has not been explored. Here, we find that epidermal growth factor (EGF) stimulation evokes a rapid alteration in small ubiquitin modifier (SUMO) target selection, while oncogene expression alters steady-state SUMO-protein profiles. A proteomic SUMO target analysis in melanoma cells identified proteins involved in cellular signaling, growth control, and neural differentiation. 相似文献
116.
Molecular isolation and sequence determination of the cDNA for the mouse sperm-specific lactate dehydrogenase-X gene 总被引:3,自引:0,他引:3
K C Wu K Chan C Y Lee Y F Lau 《Biochemical and biophysical research communications》1987,146(3):964-970
Several cDNA clones for the mouse lactate dehydrogenase-X (LDH-X), a sperm-specific glycolytic enzyme, were isolated from mouse testicular cDNA libraries constructed in the bacteriophage vectors, lambda gt11 and gt10. The largest cDNA clone contains an insert of 1135 base pairs in length and an open reading frame that encodes a 332 amino acid polypeptide with a molecular weight of 35.89 kD. The deduced amino acid sequence of this protein is in close agreement with the published sequence of mouse LDH-X obtained by direct protein sequencing. Northern analysis of RNA isolated from different tissues detected a single size mRNA of 1.5 kilobases in mouse testis but not in brain or liver. The Ldh-x structural gene was estimated to be about 12 kb in size as demonstrated by Southern hybridization analysis of mouse genomic DNA using the full-length cDNA as a probe. 相似文献
117.
The effects of auxin polar transport inhibitors,9-hydroxy-fluorene-9-carboxylic acid (HFCA);2,3,5-triiodobenzoic acid(TIBA) and trans-cinnamic acid (CA) on leaf pattern formation were investigated with shoots formed from cultured leaf explants of tobacco and cultured pedicel explants of Orychophragmus violaceus,and the seedlings of tobacco and Brassica chinensis,Although the effective concentration varies with the inhibitors used,all of the inhibitors induced the formation of trumpet-shaped and/or fused leaves.The frequency of trumpet-shaped leaf formation was related to the concentration of inhibitors in the medium.Histological observation of tobacco seedlings showed that there was only one main vascular bundle and several minor vascular bundles in normal leaves of the control,but there were several vascular bundles of more or less the same size in the trumpet-shaped leaves of treated ones.These results indicated that auxin polar transport played an important role on bilateral symmetry of leaf growth. 相似文献
118.
J. R. Ryan K. Dave E. Emmerich L. Garcia L. Yi R. E. Coleman J. Sattabongkot R. F. Dunton A. S. T. Chan R. A. Wirtz 《Medical and veterinary entomology》2001,15(2):225-230
Malaria remains the most serious vector-borne disease, affecting some 300-500 million people annually, transmitted by many species of Anopheles mosquitoes (Diptera: Culicidae). Monoclonal antibodies developed against specific circumsporozoite (CS) proteins of the main malaria parasites Plasmodium falciparum and P. vivax have been used previously for enzyme-linked immunosorbent assays (ELISA), widely employed for detection of malaria sporozoites in vector Anopheles for local risk assessment, epidemiological studies and targeting vector control. However, ELISA procedures are relatively slow and impractical for field use. To circumvent this, we developed rapid wicking assays that identify the presence or absence of specific peptide epitopes of CS protein of the most important P. falciparum and two strains (variants 210 and 247) of the more widespread P. vivax. The resulting assay is a rapid, one-step procedure using a 'dipstick' wicking test strip. In laboratory assessment, dipsticks identified 1 ng/ mL of any of these three CS protein antigens, with sensitivity nearly equal to the CS standard ELISA. We have developed and are evaluating a combined panel assay that will be both qualitative and quantitative. This quick and easy dipstick test (VecTest Malaria) offers practical advantages for field workers needing to make rapid surveys of malaria vectors. 相似文献
119.
120.
Alfred Chor San Chan Qiu Qiu Siu Wai Choi Stanley Sau Ching Wong Albert Chi Yan Chan Michael G Irwin Chi Wai Cheung 《PloS one》2016,11(2)