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271.
Don A. Driscoll Annabel L. Smith Samantha Blight John Maindonald 《Biodiversity and Conservation》2012,21(6):1607-1625
Altered fire regimes are a driver of biodiversity decline. To plan effective management, we need to know how species are influenced
by fire and to develop theory describing fire responses. Animal responses to fire are usually measured using methods that
rely on animal activity, but animal activity may vary with time since fire, potentially biasing results. Using a novel approach
for detecting bias in the pit-fall trap method, we found that leaf-litter dependent reptiles were more active up to 6 weeks
after fire, giving a misleading impression of abundance. This effect was not discovered when modelling detectability with
zero-inflated binomial models. Two species without detection bias showed early-successional responses to time since fire,
consistent with a habitat-accommodation succession model. However, a habitat specialist did not have the predicted low abundance
after fire due to increased post-fire movement and non-linear recovery of a key habitat component. Interactions between fire
and other processes therefore must be better understood to predict reptile responses to changing fire-regimes. We conclude
that there is substantial bias when trapping reptiles after fire, with species that are otherwise hard to detect appearing
to be abundant. Studies that use a survey method based on animal activity such as bird calls or animal movements, likely face
a similar risk of bias when comparing recently-disturbed with control sites. 相似文献
272.
To identify salt stress-responsive genes, we constructed a cDNA library with the salttolerant rice cultivar, Lansheng. About 15000 plasmids were extracted and dotted on filters with Biomeck 2000 HDRT system or by hand. Thirty genes were identified to display altered expression levels responding to 150 mmol/L NaCl. Among them eighteen genes were up-regulated and the remainders downregulated. Twenty-seven genes have their homologous genes in GenBank Databases. The expression of twelve genes was studied by Northern analysis. Based on the functions, these genes can be classified into five categories, including photosynthesis-related gene, transportrelated gene, metabolismrelated gene, stress-or resistancerelated gene and the others with various functions. The results showed that salt stress influenced many aspects of rice growth. Some of these genes may play important roles in plant salt tolerance. 相似文献
273.
Little information exists on mixed-species groups between primates and other mammals in Neotropical forests. In this paper, we describe three such associations observed during an extensive large-vertebrate survey in central Amazonia, Brazil. Mixed-species groups between a primate species and another mammal were observed on seven occasions between squirrel monkeys (Saimiri cf. ustus) and either South American coatis (Nasua nasua) or tayras (Eira barbara) and between brown capuchins (Cebus apella) and coatis. All associations were restricted to floodplain forest during its dry stage. We suggest that the associations involving the coatis are connected to foraging and vigilance but may be induced by a common alternative food resource at a time of food shortage. 相似文献
274.
Lentiviral vectors have been used for gene transfer into the liver but their ability to efficiently transduce quiescent hepatocytes
remains controversial. Lentivirus-mediated gene transfer is more efficient in cycling cells. We determine the effect of H-IL6
in the lentiviral transduction. The lentiviral vector was used to transduce HepG2 cells and mice liver cells, previously treated
with H-IL6. The highest transduction level was observed in HepG2 cells treated with 30 ng/mL H-IL6 and in the mice that received
4 μg H-IL6. Our results suggest that H-IL6 is an inducer of lentiviral gene transfer into the liver cells without any toxicity. 相似文献
275.
Thomas Proft 《Biotechnology letters》2010,32(1):1-10
Sortases are transpeptidases produced by Gram-positive bacteria to anchor cell surface proteins covalently to the cell wall.
The Staphylococcus aureus sortase A (SrtA) cleaves a short C-terminal recognition motif (LPXTG) on the target protein followed by the formation of an amide bond with the pentaglycine
cross-bridge in the cell wall. Over recent years, several researchers have exploited this specific reaction for a range of
biotechnology applications, including the incorporation of non-native peptides and non-peptidic molecules into proteins, the
generation of nucleic acid–peptide conjugates and neoglycoconjugates, protein circularisation, and labelling of cell surface
proteins on living cells. 相似文献
276.
Seedlings of two barley genotypes (‘Maresi’ and wild form of Hordeum spontaneum) were treated with jasmonic acid (JA 5 μM and 15 μM) for 24 h, and then subjected to water stress (PEG 6000 solution of −
1.5 MPa). JA caused an increase in the content of ABA but not in that of proline and spermidine in the two studied genotypes.
The effect of the treatment did not depend on the applied JA concentration. The pre-stress treatment with JA changed plant
response to water deficit with regard to membrane injury. Treatment with a lower JA concentration (5 μM) caused a substantial
reduction of the stress-induced membrane damage in the both genotypes. A higher JA concentration (15 μM) caused the reduction
of membrane injury only in H. spontaneum and was ineffective in ‘Maresi’. JA had no influence on the leaf water status in water-stressed plants. A possible role of
JA in leaf ABA accumulation and alleviation of cell membrane injury under water deficit is discussed.
The work was partly supported by the Polish Committee For Scientific Research, grant No 5 PO6A 036 18 相似文献
277.
Sunitinib, a small-molecule multi-targeted tyrosine kinase inhibitor, has been applied in phase II clinical trial as second-line treatment for advanced gastric cancer. In this study, we determined the effect of Sunitinib on the multidrug resistance in gastric cancer cells selected by vincristine. Our results showed that Sunitinib significantly enhanced the cytotoxicity of adriamycin, vincristine, etoposide, 5-Fluorouracil, and cisplatin in multidrug-resistant gastric cancer cells (SGC7901/VCR). Sunitinib significantly increased the intracellular accumulation and retention of rhodamine 123 in the SGC7901/VCR cells. However, Sunitinib, at a concentration that reverses MDR, had no significant effect on P-gp protein or mRNA expression levels. In addition, the present study revealed that Sunitinib inhibited Stat3 and down-regulated Bcl-2 in SGC7901/VCR cells, which might also contribute to the reversal of MDR. In conclusion, Sunitinib reverses multidrug resistance in gastric cancer cells by inhibiting P-gp transporter function and modulating Stat3 and Bcl-2. Further study with Sunitinib may be helpful for developing combination therapeutic strategy or circumventing gastric cancer MDR to other conventional anti-cancer drugs. 相似文献
278.
双尾蚜属Diuraphis Aizenberg全世界记录13种,主要分布在古北界和新北界。根据种类丰富度和特有种成分,欧亚大陆的欧洲和中亚为该属蚜虫的现代第一分布中心,北美为第二分布中心。本文提供了该属所有13个种的分种检索表。双尾蚜属蚜虫在中国共有7种,主要分布在蒙新区。它们是:麦双尾蚜Diuraphis noxia (Mordvilko), 害冰麦双尾蚜D. nociva Zhang et Liang,冰草麦蚜D. (Holcaphis) agropyronophaga Zhang, 披碱草蚜D. (Holcaphis) elymophila Zhang, 西方麦蚜D. (Holcaphis) frequens (Walker), 雀麦蚜D. (Holcaphis) bromicola Hille Ris Lambers和绒毛草蚜D. (Holcaphis) holci (Hille Ris Lambers)。对中国种类进行了简要描述。 相似文献
279.
Aims
The present study was planned to investigate the diversity of 1-aminocyclopropane-1-carboxylate (ACC) deaminase producing bacteria from the rhizosphere of wheat plants and subsequent evaluation of selected PGPR on growth enhancement of wheat seedlings under drought and saline conditions.Methods
ACC deaminase producing plant growth promoting rhizobacteria (PGPR) were isolated from the rhizosphere of wheat and identified using 16S rRNA gene sequence analysis. Isolates were evaluated for various direct and indirect plant growth promoting (PGP) traits. Plant inoculation experiment was conducted using isolates IG 19 and IG 22 in wheat to assess their plant growth promotion potential under salinity and drought stress.Results
Thirty-eight ACC deaminase producing PGPR were isolated which belonged to 12 distinct genera and falling into four phyla γ-proteobacteria, β-proteobacteria, Flavobacteria and Firmicutes. Klebsiella sp. was the most abundant genera and followed by Enterobacter sp. The isolates exhibited ACC deaminase activities ranging from 0.106–0.980 μM α- ketobutyrate μg protein?1 h?1. The isolates showed multiple PGP traits such as IAA production, phosphate, zinc, potassium solubilization and siderophore production. Enterobacter cloacae (IG 19) and Citrobacter sp. (IG 22) inoculated wheat seedlings showed notable increases in fresh and dry biomass under non-stress as well as under stressed condition.Conclusion
To the best of our knowledge this is the first report of presence of ACC deaminase activity and other PGP traits from the genus Citrobacter and Empedobacter. Our finding revealed that the γ-proteobacteria group dominated the wheat rhizosphere. Plant inoculation with PGPR could be a sustainable approach to alleviate abiotic stresses in wheat plants. These native PGPR isolates could be used as potential biofertilizers for sustainable agriculture.280.
Zou Z Wu L Ding H Wang Y Zhang Y Chen X Chen X Zhang CY Zhang Q Zen K 《The Journal of biological chemistry》2012,287(6):4148-4156
Autophagy is activated in cancer cells during chemotherapy and often contributes to tumor chemotherapy resistance. In this study, we characterized the role of microRNA-30a (miR-30a) in the coordination of cancer cell apoptosis and autophagy, which determines the sensitivity of cancer cells to chemotherapy. First, the autophagy activity in cancer cells increased after cis-dichloro-diamine platinum (cis-DDP) or Taxol treatment, as indicated by the enhanced expression of beclin 1, a key regulator of autophagy, and increased number of LC3-positive autophagosomes. Second, miRNA screening using a TaqMan probe-based quantitative RT-PCR assay identified that miR-30a, a miRNA that targets beclin 1, was significantly reduced in tumor cells by cis-DDP treatment. Forced expression of miR-30a significantly reduced beclin 1 and the autophagy activity of tumor cells induced by cis-DDP. Third, the blockade of tumor cell autophagy activity by miR-30a expression or 3-methyladenine significantly increased tumor cell apoptosis induced by cis-DDP treatment. Finally, an in vivo tumor implantation mouse model clearly showed that elevation of miR-30a in implanted tumor cells by administration of the recombinant lentivirus expressing miR-30a strongly enhanced cis-DDP-induced apoptosis of tumor cells. In conclusion, our results demonstrate for the first time that miR-30a can sensitize tumor cells to cis-DDP via reducing beclin 1-mediated autophagy and that increasing miR-30a level in tumor cells represents a novel approach to enhance the efficacy of chemotherapy during cancer treatment. 相似文献