Within-lake horizontal heterogeneity of bacterioplankton community composition (BCC) was investigated in the large and shallow subtropical Taihu Lake (2338 km(2), maximum depth < 3 m). Samples were collected at 17 sites along a trophic gradient ranging from mesotrophic to hypertrophic areas in August and September 2004. These sites cover two alternative stable states of shallow lakes, which are basically characterized by the dominance or the lack of submerged macrophytes. In the case of Taihu Lake, the macrophyte-dominated state is characterized by clear water and immobilized sediment, and the state largely lacking macrophytes is characterized by the dominance of phytoplankton, frequent wind-driven re-suspension of sediments, and a high turbidity. Three different methods, i.e. denaturing gradient gel electrophoresis (DGGE), reverse line blot hybridization (RLB) with probes targeting 17 freshwater bacterial groups, and 16S rRNA gene cloning and sequencing, were used for analysis of BCC. The BCC varied strongly between the two alternative ecological states, but less pronounced between phytoplankton-dominated sites even spanning chlorophyll a gradients from 16.5 (mesotrophic) to 229.8 microg l(-1) (hypertrophic). The 16S rRNA gene library representing the turbid water state contained many sequences closely related to sequences previously obtained from soil or freshwater sediment samples. Furthermore, sequences representing two new lineages of freshwater Actinobacteria were obtained from the investigated samples. Comparative statistical analyses of BCC along the investigated ecological gradients revealed that the dominance of submersed macrophytes was the most influential factor on BCC, responsible for a major part of the observed within-habitat heterogeneity of BCC in Taihu Lake. 相似文献
The aim of this study was to investigate the expression of ZEB1 in gastric carcinoma, its correlation with the clinicopathology of gastric carcinoma, and the role of ZEB1 in invasion and metastasis in gastric carcinoma. ZEB1 expression was analyzed by immunohistochemistry and Western blot in 45 gastric carcinoma tissue samples that contained the adjacent gastric mucosa. The correlation between ZEB1 expression, the occurrence and development of gastric cancer, and clinical pathology was investigated. ZEB1 expression in the human gastric carcinoma cell line AGS was downregulated by RNA interference, and changes in ZEB1 expression corresponded with changes in the invasive and metastatic ability of AGS cells. Immunohistochemistry revealed that ZEB1 protein expression in gastric carcinoma tissues was significantly higher than in normal gastric mucosa tissues (p < 0.001). A lower degree of differentiation of gastric cancer (p = 0.009), a higher TNM (tumor, node, and metastasis) stage (p = 0.010), and a larger scope of invasion were correlated with higher expression of ZEB1 (p = 0.041, 0.002). However, the expression of ZEB1 in gastric carcinoma tissue was independent of gender, age, and tumor size (p > 0.05). Western blot results also showed that ZEB1 protein expression was significantly higher in gastric carcinoma tissue than in the adjacent normal gastric mucosa tissue (p = 0.008). A lower degree of differentiation of the gastric carcinoma correlated with a higher TNM stage, and a larger scope of invasion correlated with increased ZEB1 expression (p = 0.023). Transfection of ZEB1 siRNA in AGS cells significantly decreased the expression level of ZEB1 protein (p = 0.035). Furthermore, the number of cells that could pass through the Transwell chamber was significantly lower in the transfected group than in the non-transfected control group (p = 0.039), indicating that the suppression of ZEB1 expression could significantly reduce the invasive and metastatic ability of AGS cells (p = 0.005). Concluding, in gastric carcinoma tissue, overexpression of ZEB1 may be related to the occurrence and development as well as invasion and metastasis of gastric carcinoma. 相似文献
Antioxidant activity is one of the important probiotic characteristics for lactic acid bacteria including Lactobacillus plantarum, which is used for food fermentation or as a probiotic supplement. L. plantarum FLPL05 is a novel strain originally isolated from a healthy elderly individual of longevity. The organism has been demonstrated to exhibit high antioxidant property. However, there are limited genomic insights into the antioxidant properties of this organism. In this study, we performed whole-genome analysis regarding its antioxidant property. L. plantarum FLPL05 exhibited higher antioxidant activity compared with that of L. plantarum strains ATCC14917, ATCC8014, and WCFS1. The antioxidant capacity of L. plantarum FLPL05 was genetically linked to its antioxidant system, i.e., glutathione and thioredoxin involved in global regulation of defense against hydrogen peroxide challenge. L. plantarum FLPL05 was further examined for its antioxidant potential in d-Gal-induced aging mice and exhibited a significant increase in the activity of serum glutathione peroxidase (GSH-PX) and a decrease in the level of malondialdehyde (MDA). Moreover, our analyses exhibited a complete gene cluster including plnA, plnB, plnC, plnD, plnE, plnF, plnG, plnH, plnI, plnJ, plnK, plnM, plnN, plnO, plnP, plnQ, plnST, plnU, plnV, plnW, plnX, and plnY for production of bacteriocin. Our results suggest that L. plantarum FLPL05 could be a probiotic candidate.
Fullerene‐based carbons are promising electrode materials for supercapacitors due to their unique carbon structures and tunable architectures at the molecular level. By introducing various functional groups with many elements on the fullerene cages, diverse in situ metal/nonmetal‐doped carbon materials with enhanced pseudocapacitances and/or double layer capacitances can be prepared. In the present work, a fullerene derivative, ferrocenylpyrrolidine C60, containing nitrogen and iron, is chosen as the only precursor. A unique microstructure is fabricated by a liquid–liquid interfacial precipitation process. Subsequently, a facile, one‐step annealing of the microstructure at different temperatures is performed. A series of in situ N and Fe‐codoped laminated 3D hierarchical carbon composites in the shape of a cross are successfully synthesized. The as‐prepared N and Fe‐codoped carbon material treated at 700 °C exhibits a high specific capacitance of 505.4 F g?1 at 0.1 A g?1. To the best knowledge, this is the highest supercapacitor capacitance based on fullerene electrode materials. The use of a fullerene derivative as an in‐situ doped carbon for applications in energy storage opens a new avenue for developing future synthetic strategies to extend the repertoire of electrode materials with high performance. 相似文献
MHC class I proteins mediate functions in anti-pathogen defense. MHC diversity has already been investigated by many studies in model avian species, but here we chose the bar-headed goose, a worldwide migrant bird, as a non-model avian species. Sequences from exons encoding the peptide-binding region (PBR) of MHC class I molecules were isolated from liver genomic DNA, to investigate variation in these genes. These are the first MHC class I partial sequences of the bar-headed goose to be reported. A preliminary analysis suggests the presence of at least four MHC class I genes, which share great similarity with those of the goose and duck. A phylogenetic analysis of bar-headed goose, goose and duck MHC class I sequences using the NJ method supports the idea that they all cluster within the anseriforms clade. 相似文献
Current models suggest that (i) filamentous bacteria are protected against predation by nanoflagellates, (ii) prey size is positively correlated with prey-predator contact probability, and (iii) contact probability is mainly responsible for size-selective predation by interception-feeding flagellates. We used five strains of filamentous bacteria and one bacterivorous nanoflagellate, Ochromonas sp. strain DS, to test these assumptions. The five strains, including one spirochete and four Betaproteobacteria strains, were isolated by the filtration-acclimatization method. All five strains possess flexible cells, but they differ in average cell length, which ranged from 4.5 to 13.7 μm. High-resolution video microscopy was used to measure contact, capture, and ingestion rates, as well as selectivity of the flagellate feeding. Growth and feeding experiments with satiating and nonsatiating food conditions, as well as experiments including alternative well-edible prey, were performed. In contrast to predictions by current models, the flagellate successfully consumed all the tested filamentous strains. The ingestion rate was negatively correlated with bacterial length. On the other hand, the lengths of the filamentous bacteria were not positively correlated to the contact rate and capture rate but were negatively correlated to ingestion efficiency. In experiments including alternative nonfilamentous prey, the flagellates showed negative selection for filamentous bacteria, which was independent of food concentration and is interpreted as a passive selection. Our observations indicate that (i) size alone is not sufficient to define a refuge for filamentous bacteria from nanoflagellate predation and (ii) for the investigated filamentous bacteria, prey-predator contact probability could be more influenced by factors other than the prey size. 相似文献
To study how archaeal community responds to environmental changes, we investigated archaeal community structures in waters of three Tibetan saline lakes in northwestern China (Gahai, Xiaochaidan, and Charhan Lakes) with 16S rRNA gene phylogenetic analysis. Temperature, pH, and water chemistry (major anions and cations) of the lakes were measured. Three archaeal clone libraries were constructed with a total of 297 sequences. Incorporating our previous data obtained from other lakes on the Tibetan Plateau, we performed statistical analyses to identify dominant environmental parameters that could account for the observed variations in archaeal community structure. We concluded that salinity and water chemistry (Na and bicarbonate concentration in particular) played an important role in shaping archaeal community. In particular, the relative abundance of archaeal 16S rRNA genes affiliated with the Halobacteriales of the Euryarchaeota increased with salinity, whereas that of crenarchaeotal 16S rRNA gene sequences showed the opposite trend. Crenarchaeotal 16S rRNA gene sequences were retrieved from lake waters with salinity up to 28.3%. These results have important implications for our understanding of response of archaeal community to environmental changes in high-altitude lake ecosystems. 相似文献
Fine mapping of the novel thermo-sensitive genic male sterility locustms9-1in the traditional TGMS line HengnongS-1 revealed that theMALE STERILITY1homologOsMS1is the candidate gene.
Abstract
Photoperiod-thermo-sensitive genic male sterility (P/TGMS) has been widely used in the two-line hybrid rice breeding system. HengnongS-1 is one of the oldest TGMS lines and is often used in indica two-line breeding programs in China. In this study, our genetic analysis showed that the TGMS gene in HengnongS-1 was controlled by a single recessive gene that was non-allelic with the other TGMS loci identified, including C815S, Zhu1S and Y58S. Using SSR markers and bulked segregant analysis, we located the TGMS locus on chromosome 9 and named the gene tms9-1. Fine mapping further narrowed the tms9-1 loci to a 162 kb interval between two dCAPS markers. Sequence analysis revealed that a T to C substitution results in an amino acid change in the tms9-1 candidate gene (Os09g27620) in HengnongS-1 as compared to Minghui63. Sequencing of other rice accessions, including six P/TGMS lines, seven indica varieties and nine japonica varieties, showed that this SNP was exclusive to HengnongS-1. With multiple sequence alignment and expression pattern analyses, the rice MALE STERILITY1 homolog OsMS1 gene was identified as the candidate gene for tms9-1. Therefore, our study identified a novel TGMS locus and will facilitate the functional identification of the tms9-1 gene. Moreover, the markers linked to the tms9-1 gene will provide useful tools for the development of new TGMS lines by marker-assisted selection in two-line hybrid rice breeding programs. 相似文献