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林农复合生态系统的原理、特点及其类型 总被引:1,自引:0,他引:1
林农复合生态系统是根据生态位、生物种群之间共生、边缘效应、利用层、食物链“加环”和生态系统工程等原理建立起来的。林农复台生态系统依历史发展过程可分为原始林农复合系统、传统林农复会系统和现代林农复合系统;根据生产方式可分为“牧童”式、林农轮作式、林农间作式、食物网链式、树木菜园式、塘雅系统式和复合母系统式等7种类型;依复台种类及其用途来分,主要有林、农系统,林、牧系统,林、渔系统,林、渔、农系统。林、渔、牧系统,林、食用菌系统,林、水生作物、渔系统和林.副系统等8种类型。 相似文献
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Yaomin Luo Xintong Lu Wenrong Ma Yang Xiao Chen Wei Xiaoxia Yuan Yueyue Wu Yunlin Wang Yiman Xiong Xin Yu Xue Wu Siqi He Yayudie Liu Jinjing Wang Qing Wu Hui Zhou Zhen Jiang 《Journal of cellular and molecular medicine》2023,27(22):3591-3600
Long non-coding RNAs (lncRNA) have an extensive role in the progression and chemoresistance of gastric cancer (GC). Deeply study the regulatory role of lncRNAs could provide potential therapeutic targets. The aim of this study is to explore the regulatory role of HOTAIR in the progression and oxaliplatin resistance of GC. The expression of HOTAIR in GC and cell lines were detected by using qRT-PCR. Cell proliferation and apoptosis were analysed by CCK-8, EdU incorporation and flow cytometry. Luciferase reporter assay was used to identify the interaction between HOTAIR and ABCG2 (ATP-binding cassette (ABC) superfamily G member 2, ABCG2) via miR-195-5p. The regulatory functions were verified by using molecular biology experiments. HOTAIR was significantly overexpressed in GC and associated with poor prognosis. Knock-down of HOTAIR inhibited the GC cells proliferation and oxaliplatin resistance, while overexpression of HOTAIR showed opposite functions. Further studies found that HOTAIR acted as a competing endogenous RNA (ceRNA) to absorb miR-195-5p and elevated the expression of ABCG2, which leads to resistance of GC cells to oxaliplatin. Taken together, our findings demonstrated that HOTAIR regulates ABCG2 induced resistance of GC to oxaliplatin through miR-195-5p signalling and illustrate the great potential of developing new therapeutic targets for GC patients. 相似文献
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楝酰胺类化合物存在于楝属植物中,因其独特的化学结构而具有杀虫、抗炎及抗癌的活性.目前研究发现,楝酰胺类化合物对多种癌症如肺癌、肾癌、胰腺癌、恶性外周神经鞘瘤等都具有独特的细胞凋亡作用,而对正常细胞无毒害作用.楝酰胺类化合物抗肿瘤的机制主要有:抑制癌细胞翻译起始、调控细胞周期、诱导肿瘤细胞凋亡、抑制细胞增殖、降低药物细胞毒性等.因此,楝酰胺及其衍生物作为潜在抗癌药物也有极大的应用前景,成为近年来的研究热点.本综述总结了楝属植物中的次生代谢产物-楝酰胺类化合物的发现过程、结构特征和抗癌活性,重点阐述了其在癌症中的作用机制.以期为楝酰胺类化合物的进一步研究和开发利用提供理论依据和研究思路,并对楝酰胺类化合物的应用前景进行了展望. 相似文献
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Jinjin Cui Shiwu He Xiuling Ji Lianbing Lin Yunlin Wei Qi Zhang 《Biotechnology letters》2016,38(7):1155-1164
Objectives
To elucidate the biosynthesis pathway of linoleic acid and α-linolenic acid in Rhodosporidium kratochvilovae YM25235 and investigate the correlation of polyunsaturated fatty acids with its cold adaptation.Results
A 1341 bp cDNA sequence, designated as RKD12, putatively encoding a Δ12-desaturase was isolated from YM25235. Sequence analysis indicated that this sequence comprised a complete ORF encoding 446 amino acids of 50.6 kDa. The encoded amino acid sequence shared higher similarity to known fungal Δ12-desaturases that are characteristic of three conserved histidine-rich motifs. RKD12 was further transformed into Saccharomyces cerevisiae INVScl for functional characterization. Fatty acid analysis showed the yeast transformants accumulated two new fatty acids: linoleic acid and α-linolenic acid. Furthermore, mRNA expression level of RKD12 and the content of linoleic acid and α-linolenic acid were increased significantly with the culture temperature downshift from 30 to 15 °C, which might be helpful for the cold adaptation of YM25235.Conclusion
RKD12 is a novel bifunctional ?12/?15-desaturase gene, and the increased RKD12 mRNA expression level and PUFAs content at low temperature might be helpful for the cold adaptation of YM25235.7.
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Effects of hydrodynamics on phosphorus concentrations in water of Lake Taihu,a large,shallow, eutrophic lake of China 总被引:4,自引:0,他引:4
Guangwei Zhu Boqiang Qin Guang Gao Lu Zhang Liancong Luo Yunlin Zhang 《Hydrobiologia》2007,581(1):53-61
To understand the effect of hydrodynamical process on water phosphorus concentration, wind, wave, and several water quality
indices were observed in Meiliang Bay, a shallow and eutrophic bay locates in north of Lake Taihu. During the 7 day observation
period, wind speed and significant wave height were recorded more than 3 h per day, and water samples were collected in five
water-depth layers once a day. Hydrodynamical disturbance had no significant correlationship with the water quality at the
top layer when the significant wave height was smaller than 30 cm, but it significantly increased suspended solids (SS) concentration
of the bottom water layer. Concentrations of nutrients showed no positive correlationship with SS concentration in the water
body. Intensive sediment resuspension may not have occurred when the hydrodynamic stress on sediment was only a little higher
than the critical stress for sediment resuspension. A new method for confirming the critical stress for intensive sediment
resuspension and nutrient release still needs to be developed. The range of the water quality indices was quite high during
the seven days of observation. High variation seems to be a common character of large shallow lakes like Taihu. 相似文献
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Guanghai Yu Xiaoqiang Jia Jianping Wen Guoying Wang Yunlin Chen 《World journal of microbiology & biotechnology》2011,27(8):1859-1868
The effects of eight cofactors of enzymes on daptomycin production were investigated in this work, which included nicotinic
acid (VPP), riboflavin (VB2), heme, thiamine (VB1), biotin (VH), cyanocobalamin (VB12), tetrahydrofolic acid (THF) and pyridoxal 5-phosphate (VB6). The dry cell weight (DCW), consumption of glucose, and daptomycin production were obviously improved when proper amount
of exogenous cofactors were supplemented in the medium. The effects of heme, THF, VB12 and VB6 on daptomycin production were especially notable. The daptomycin yield enhanced 363, 104, 53 and 46%, respectively, when
optimized amount of these four cofactors were supplemented in the broth. Moreover, the daptomycin yield further increased
to 632 mg/l, which was over 4.5-fold higher than that of the control (without cofactors), at 132 h in a 7.5-l fermenter, by
supplementation all of the eight cofactors at optimized concentrations (VPP 4 mg/l, VB2 0.5 mg/l, heme 9 mg/l, VB1 0.4 mg/l, VH 0.1 mg/l, VB12 0.04 mg/l, THF 6 mg/l and VB6 0.4 mg/l). Further, the effects of cofactors on the corresponding key enzymes and important intracellular metabolites were
studied in order to elucidate the mechanism of enhancement of daptomycin production by manipulation of cofactors concentration
in the fermentation culture. It is suggested that this strategy for increasing the daptomycin production in Streptomyces roseosporus LC-51 by manipulation of cofactors concentration in the fermentation culture may provide an alternative approach to enhance
the production of metabolites in other Streptomyces. 相似文献