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991.
Sheng Qin Jie Li Hua-Hong Chen Guo-Zhen Zhao Wen-Yong Zhu Cheng-Lin Jiang Li-Hua Xu Wen-Jun Li 《Applied and environmental microbiology》2009,75(19):6176-6186
Endophytic actinobacteria are relatively unexplored as potential sources of novel species and novel natural products for medical and commercial exploitation. Xishuangbanna is recognized throughout the world for its diverse flora, especially the rain forest plants, many of which have indigenous pharmaceutical histories. However, little is known about the endophytic actinobacteria of this tropical area. In this work, we studied the diversity of actinobacteria isolated from medicinal plants collected from tropical rain forests in Xishuangbanna. By the use of different selective isolation media and methods, a total of 2,174 actinobacteria were isolated. Forty-six isolates were selected on the basis of their morphologies on different media and were further characterized by 16S rRNA gene sequencing. The results showed an unexpected level of diversity, with 32 different genera. To our knowledge, this is the first report describing the isolation of Saccharopolyspora, Dietzia, Blastococcus, Dactylosporangium, Promicromonospora, Oerskovia, Actinocorallia, and Jiangella species from endophytic environments. At least 19 isolates are considered novel taxa by our current research. In addition, all 46 isolates were tested for antimicrobial activity and were screened for the presence of genes encoding polyketide synthetases and nonribosomal peptide synthetases. The results confirm that the medicinal plants of Xishuangbanna represent an extremely rich reservoir for the isolation of a significant diversity of actinobacteria, including novel species, that are potential sources for the discovery of biologically active compounds.The class Actinobacteria accounts for a high proportion of soil microbial biomass and contains the most economically significant prokaryotes, producing more than half of the bioactive compounds in a literature survey (46), including antibiotics (6), immunosuppressive agents (55), antitumor agents (18), and enzymes (64). Actinobacteria belonging to the genus Streptomyces, in particular, are excellent producers. The emergence of drug resistance in many bacterial pathogens and the current increase in the number of fungal infections has caused a resurgence of interest in finding new reserves of biologically active compounds (63). As the search for novel natural products continues, it becomes apparent that the rate of discovery of new compounds from soil streptomycetes has decreased, whereas the rate of reisolation of known compounds has increased (28). Recently, evidence has accumulated that rare actinomycete species, which are often very difficult to isolate and cultivate, might represent a unique source of novel biologically active compounds (4). On the other hand, new microbial habitats need to be examined in the search for novel bioactive compounds. One biologically important but relatively overlooked niche is the inner tissues of higher plants. Early studies have demonstrated that some actinobacteria can form intimate associations with plants and colonize their inner tissues. Frankia species and Streptomyces scabies can penetrate their hosts and establish either pathogenic or endophytic associations (5, 24). The actinomycetes that reside in the tissues of living plants and do not visibly harm the plants are known as endophytic actinobacteria (37). These actinobacteria are relatively unstudied and are potential sources of novel natural products for exploitation in medicine, agriculture, and industry (73).Endophytic actinobacteria have attracted attention in recent years, with increasing reports of isolates from a range of plant types, including crop plants (cereals, such as wheat and rice, as well as potatoes, carrots, tomatoes, and citrus) (2, 16, 62, 71, 74, 80) and medicinal plants (75, 88). The culturable endophytic actinobacteria from these plants were found to fall within a narrow species distribution: Streptomyces spp. were the predominant species, and Microbispora, Micromonospora, Nocardioides, Nocardia, and Streptosporangium were the common genera. Endophytic actinobacteria have been demonstrated to improve and promote the growth of host plants as well as to reduce disease symptoms caused by plant pathogens through various mechanisms, including the production of secondary metabolites, which are used in direct antagonism against pests and diseases (9, 10, 12), changes in host physiology (42), and the induction of systemic acquired resistance in plants (15). Another significant function found for these actinobacteria was antibiotic activity, suggesting that endophytic actinobacteria can be an interesting source for bioprospecting. New antibiotics from endophytic Streptomyces spp.—alnumycin, munumbicins A to D, and coronamycins—have been reported (7, 11). Recently, two novel antitumor anthraquinones, lupinacidins A and B, were isolated from a new endophytic Micromonospora sp. (43). Moreover, new species of endophytic actinobacteria have been increasingly reported (25, 35). Thus, endophytic actinobacteria are expected to be potential sources of new species and new bioactive agents.Of the myriad ecosystems on earth, those with the greatest general biodiversity seem also to have the greatest number and the greatest diversity of endophytes (73). Tropical and temperate rain forests are the most biologically diverse terrestrial ecosystems on earth and thus the greatest possible resource for the acquisition of novel microorganisms and their products (73). One area of enormous plant biodiversity is Xishuangbanna, located in the People''s Republic of China at the border with Myanmar. This area lies at the ecotone between the Asian tropics and subtropics and is dominated by tropical seasonal rain forests (87). Xishuangbanna contains more than 5,000 species of vascular plants, comprising 16% of China''s total plant diversity, and more than 3,000 are endemic species (53, 60), many of which have ethnobotanical histories. Until the present, little research was carried out to isolate endophytic actinobacteria and their secondary metabolites from Xishuangbanna (36, 86). In our long-term study of endophytic actinobacterial diversity and bioactive metabolites from tropical rain forest medicinal plants in Xishuangbanna, many bioactive endophytic Streptomyces spp. have been isolated (49). However, the work to date is insufficient to provide a general understanding of the diversity, distribution, and ecology of tropical rain forest endophytic actinobacteria and to facilitate further exploitation of the diverse functions of this novel microbial source.In the present study, the diversity of rare endophytic actinobacteria associated with medicinal plants from the tropical rain forest in Xishuangbanna was investigated by combining special culturing techniques. The selected isolates were also identified by 16S rRNA gene analysis. The overall aims of this study were (i) to analyze the actinobacterial community and reveal whether the rain forest investigated in Xishuangbanna represents a valuable source for abundant endophytic actinobacteria and new species, (ii) to evaluate the antimicrobial activities of these actinobacteria and the biosynthetic potential of related secondary metabolites, and (iii) to study the relationships between the taxa of these endophytic actinobacteria and the isolation methods applied. 相似文献
992.
Herpes simplex virus type 1 immediate-early protein Vmw110 reactivates latent herpes simplex virus type 2 in an in vitro latency system. 总被引:6,自引:27,他引:6
Reactivation of latent herpes simplex virus type 2 (HSV-2) by the immediate-early protein Vmw110 was studied by using an in vitro latency system. Adenovirus recombinants that express Vmw110 reactivated latent HSV-2. An HSV-1 mutant possessing a deletion in a carboxy-terminal region of Vmw110 reactivated latent HSV-2, whereas mutant FXE, which has a deletion in the second exon, did not. Therefore, Vmw110 alone is required to reactivate latent HSV-2 in vitro, and the region of Vmw110 defined by the deletion in FXE is important for this process. 相似文献
993.
994.
Cytochrome c release and mitochondrial permeability transition (MPT) play important roles in apoptosis. In this study, we found that selenium, an essential trace element, induced mitochondrial membrane potential (Delta psi(m)) loss, swelling, and cytochrome c release in isolated mitochondria. All of the above observations were blocked by cyclosporin A (CsA), which is a specific inhibitor to permeability transition pore (PTP), indicating selenite-induced mitochondrial changes were mediated through the opening of PTP. In physiological concentration, selenite could induce mitochondria at low-conductance PTP 'open' probability, which is correlated to regulate the physiological function, whereas in toxic concentration, induce mitochondria at high-conductance PTP 'open' probability and rapidly undergo a process of osmotic swelling following diffusion toward matrix as for inducer (Ca(2+)/P(i)). Selenite also induced other mitochondrial marker enzymes including monoamine oxidase (MAO) and mitochondria aspartate aminotransferase (mAST). Oligomycin inhibited the selenite-induced cytochrome c release and Delta psi(m) loss, showing that F(0)F(1)-ATPase was important in selenite or Ca(2+)/P(i)-induced MPT. 相似文献
995.
Yang Cheng Pu Shiming Zhu Huan Qin Wanying Zhao Hongxia Guo Ziqi Zhou Zuping 《Molecular and cellular biochemistry》2022,477(3):897-914
Molecular and Cellular Biochemistry - Neural stem cells (NSCs) are responsible for maintaining the nervous system and repairing damages. Utility of NSCs could provide a novel solution to treat... 相似文献
996.
Zhu Kai Guo Song Han Guoyi Qiang Xiancheng Ma Mengmeng Xu Qinglei Tang Wenjie Tan Jun 《Molecular biology reports》2022,49(5):3783-3792
Molecular Biology Reports - Oxidative stress in the intervertebral disc leads to nucleus pulposus (NP) degeneration by inducing cell apoptosis. However, the molecular mechanisms underlying this... 相似文献
997.
Chang Gong Ziliang Cheng Yaping Yang Jun Shen Yingying Zhu Li Ling Wanyi Lin Zhigang Yu Zhihua Li Weige Tan Chushan Zheng Wenbo Zheng Jiajie Zhong Xiang Zhang Yunjie Zeng Qiang Liu R.Stephanie Huang Andrzej L.Komorowski Eddy S.Yang Fran?ois Bertucci Francesco Ricci Armando Orlandi Gianluca Franceschini Kazuaki Takabe Suzanne Klimberg Naohiro Ishii Angela Toss Mona P.Tan Mathew A Cherian Erwei Song 《中国科学:生命科学英文版》2022,65(11):2205-2217
Patients with hormone receptor(HR)-positive tumors breast cancer usually experience a relatively low pathological complete response(p CR) to neoadjuvant chemotherapy(NAC). Here, we derived a 10-micro RNA risk score(10-mi RNA RS)-based model with better performance in the prediction of p CR and validated its relation with the disease-free survival(DFS) in 755 HRpositive breast cancer patients(273, 265, and 217 in the training, internal, and external validation sets, respectively). This model,pres... 相似文献
998.
999.
1000.
Genome-wide identification and expression profiling of ankyrin-repeat gene family in maize 总被引:1,自引:0,他引:1
Haiyang Jiang Qingqing Wu Jing Jin Lei Sheng Hanwei Yan Beijiu Cheng Suwen Zhu 《Development genes and evolution》2013,223(5):303-318
Members of the ankyrin repeats (ANK) gene family encode ANK domain that are common in diverse organisms and play important roles in cell growth and development, such as cell-cell signal transduction and cell cycle regulation. Recently, genome-wide identification and evolutionary analyses of the ANK gene family have been carried out in Arabidopsis and rice. However, little is known regarding the ANK genes in the entire maize genome. In this study, we described the identification and structural characterization of 71 ANK genes in maize (ZmANK). Then, comprehensive bioinformatics analyses of ZmANK genes family were performed including phylogenetic, domain and motif analysis, chromosomal localization, intron/exon structural patterns, gene duplications and expression profiling. Domain composition analyses showed that ZmANK genes formed ten subfamilies. Five tandem duplications and 14 segmental duplications were identified in ZmANK genes. Furthermore, we took comparative analysis of the total ANK gene family in Arabidopsis, rice and maize, ZmANKs were more closely paired with OsANKs than with AtANKs. At last, expression profile analyses were performed. Forty-one members of ZmANK genes held EST sequences records. Semi-quantitative expression and microarray data analysis of these 41 ZmANK genes demonstrated that ZmANK genes exhibit a various expression pattern, suggesting that functional diversification of ZmANK genes family. The results will present significant insights to explore ANK genes expression and function in future studies in maize. 相似文献