UVB-based mate-choice cues used by females of the jumping spider Phintella vittata

Although there are numerous examples of animals having photoreceptors sensitive to UVA (315-400 nm) [1] and relying on UVA-based mate-choice cues [2-5], here we provide the first evidence of an animal using UVB (280-315 nm) for intraspecific communication. An earlier study showed that Phintella vittata, a jumping spider (Salticidae) from China, reflects UVB [6]. By performing six series of binary mate-choice experiments in which we varied lighting conditions with filters (UVB+ [no filter] versus UVB-, UVB+ versus ND1, UVB+ versus ND2, UVB- versus ND1, UVB- versus ND2, and UVB- versus UVA-), we show that significantly more UVB + males than UVB- males are chosen by females as preferred mates. Female preference for UVB-reflective males is not affected by differences in brightness or by UVA.     

Comparison of protein and peptide prefractionation methods for the shotgun proteomic analysis of Synechocystis sp. PCC 6803

Proteome analysis by gel-free "shotgun" proteomics relies on the simplification of a peptide mixture before it is analyzed in a mass spectrometer. While separation on a reverse-phase (RP) liquid chromatographic column is widely employed, a variety of other methods have been used to fractionate both proteins and peptides before this step. We compared six different protein and peptide fractionation workflows, using Synechocystis sp. PCC 6803, a useful model cyanobacterium for potential exploitation to improve its production of hydrogen and other secondary metabolites. Pre-digestion protein separation was performed by strip-based isoelectric focusing, one-dimensional polyacrylamide gel electrophoresis, or weak anion exchange chromatography, while pre-RP peptide separation was accomplished by isoelectric focusing (IEF) or strong cation exchange chromatography. Peptides were identified using electrospray ionization quadrupole time of flight-tandem mass spectrometry. Mass spectrometry (MS) and tandem mass spectra were analyzed using ProID software employing both a single organism database and the entire NCBI non-redundant database, and a total of 776 proteins were identified using a stringent set of selection criteria. Method comparisons were made on the basis of the results obtained (number and types of proteins identified), as well as ease of use and other practical aspects. IEF-IEF protein and peptide fractionation prior to RP gave the best overall performance.     

Proteomic analysis of Saccharomyces cerevisiae under high gravity fermentation conditions

Saccharomyces cerevisiae KAY446 was utilized for ethanol production, with glucose concentrations ranging from 120 g/L (normal) to 300 g/L (high). Although grown in a high glucose environment, S. cerevisiae still retained the ability to produce ethanol with a high degree of glucose utilization. iTRAQ-mediated shotgun proteomics was applied to identify relative expression change of proteins under the different glucose conditions. A total of 413 proteins were identified from three replicate, independent LC-MS/MS runs. Unsurprisingly, many proteins in the glycolysis/gluconeogenesis pathway showed significant changes in expression level. Twenty five proteins involved in amino acid metabolism decreased their expression, while the expressions of 12 heat-shock related proteins were also identified. Under high glucose conditions, ethanol was produced as a major product. However, the assimilation of glucose as well as a number of byproducts was also enhanced. Therefore, to optimize the ethanol production under very high gravity conditions, a number of pathways will need to be deactivated, while still maintaining the correct cellular redox or osmotic state. Proteomics is demonstrated here as a tool to aid in this forward metabolic engineering.     

Selenium blocks porcine circovirus type 2 replication promotion induced by oxidative stress by improving GPx1 expression

Porcine circovirus type 2 (PCV2) is recognized as a key infectious agent in postweaning multisystemic wasting syndrome (PMWS), but not all pigs infected with PCV2 will develop PMWS. The aim of this work was to explore the relationships among PCV2 infection, oxidative stress, and selenium in a PK-15 cell culture model of PCV2 infection. The results showed that oxidative stress induced by H(2)O(2) treatment increased PCV2 replication as measured by PCV2 DNA copies and the number of infected cells. Furthermore, PCV2 replication was inhibited by selenomethionine (SeMet) at a high concentration (6μM) and the increase in PCV2 replication by oxidative stress was blocked by SeMet at physiological concentrations (2 or 4μM). PCV2 infection caused a decrease in glutathione peroxidase 1 (GPx1) activity but an increase in GPx1 mRNA levels, suggesting that GPx1 may represent an important defense mechanism during PCV2 infection. SeMet did not significantly block the promotion of PCV2 replication in GPx1-knockdown cells. This observation correlates with the observed influence of SeMet on GPx1 mRNA and activity in GPx1-knockdown cells, indicating that GPx1 plays a key role in blocking the promotion of PCV2 replication. We conclude that differences in morbidity and severity of PMWS observed on different pig farms may be related to variations in oxidative stress and that selenium has a potential role in the control of PCV2 infection.     

Comparative study of the cytotoxicity of the nanosized and microsized tellurium powders on HeLa cells

To compare the cytotoxicity on HeLa cells induced by nanosized and microsized tellurium powders, HeLa cells were exposed to different concentrations of tellurium powders (0, 50, 100, 150 and 200 μg/mL) for 12 h. In this study, detection of a series of biomarkers, including reactive oxygen species (ROS), glutathione (GSH), 8-hydroxy-2′-deoxyguanosine (8-OHdG), in addition to DNA and protein crosslink (DPC) and MTTassay, were conducted to evaluate the cytotoxicity. It is indicated that compared with the control group, there was no significant difference in the induced cytotoxicity at concentrations lower than 50 μg/mL for both nanosized and microsized tellurium powders. While there appears a significant difference in the induced cytotoxicity for nanosized tellurium powders when the concentration is higher than 100 μg/mL as well as for microsized tellurium powders when the concentration is higher than 200 μg/mL. Moreover, it is found that the cytotoxicity induced on HeLa cells exhibits a certain dose-effect relationship with the concentration of tellurium powders. A conclusion has been reached that the toxicity on HeLa cells can be induced by both nanosized and microsized tellurium powders, and the toxicity of the nanosized tellurium powders is significantly greater than the microsized one.     

Generation and analysis of expressed sequence tags for microsatellite marker development in Calamus simplicifolius C. F. Wei

Rattans serve as an important source of raw non-wood materials for furniture and handicraft industries worldwide. However, their genomic sequence information in public databases is very limited. In this study, a set of 2,528 good-quality expressed sequence tags (ESTs) were generated from a full-length cDNA library constructed previously with root, stem and male inflorescence tissues of Calamus simplicifolius C. F. Wei, a rattan species native to Hainan Island, China. The ESTs were assembled into 1,588 unigenes, including 1,221 singletons and 367 contigs. BlastX searches against the GenBank non-redundant protein database revealed that 1,248 (78.6 %) unigenes had at least one significant match (E ≤ 10^?5). The gene ontology functional classification assigned 991, 669 and 977 of the unigenes to the cellular component, molecular function and biological process categories, respectively. A total of 71 simple sequence repeat (SSR) loci were developed among these ESTs, including 65 polymorphic across 19 rattan species representing three genera. High levels of cross-species/genus transferability were observed for the EST-SSRs. For the polymorphic EST-SSR markers, the number of alleles per locus and polymorphic information content ranged from 2 to 25 (mean 11.1) and from 0.135 to 0.949 (mean 0.695), respectively. The EST sequences and the EST-SSR primers have been deposited in GenBank databases of EST (IDs JK838364–40891) and Probe (IDs Pr16718978–9048, to be assigned).     

不同强度运动对大鼠心肌细胞凋亡的影响

通过比较不同强度负荷运动中大鼠心肌细胞的凋亡及其相关基因B细胞淋巴瘤-2(Bcl-2)表达变化的实验研究,试图找出它们之间相互关系的一般规律,为训练制定合理的、适宜的运动负荷提供理论依据.采用8周龄雄性SD大鼠30只,随机分为安静对照组(NC)、中等强度运动组(ME)和大强度运动组(HE),测定心肌细胞的凋亡指数和相关基因B细胞淋巴瘤-2,采用HE染色法观察心肌细胞.结果表明:中等强度运动组和大强度运动组的心肌都有细胞凋亡现象.中等强度运动组的心肌细胞凋亡指数显著升高且差异具有显著性意义(P<0.05),不同强度运动组差异无统计学意义.3组均有Bcl-2表达,中等强度运动组和安静对照组相比具有极显著性差异(P<0.01),大强度运动组和安静对照组相比有显著性差异(P<0.05),大强度运动组表达显著低于中等强度运动组(P<0.05).不适宜的运动负荷会造成大鼠心肌细胞凋亡增加,并且可能参与心肌的损害过程.     

5-Methoxytryptamine Inhibits Cyclic AMP Accumulation in Cultured Retinal Neurons Through Activation of a Pertussis Toxin-Sensitive Site Distinct from the 2-[125I]Iodomelatonin Binding Site

Abstract: Melatonin and 5-methoxytryptamine inhibited forskolin-stimulated cyclic AMP formation in cultured neural cells prepared from embryonic chick retina. Both methoxyindoles exhibited similar potency and efficacy, with EC₅₀ values of 0.8 n M for melatonin and 7.2 n M for 5-methoxytryptamine. Inhibition of cyclic AMP formation by 5-methoxytryptamine or melatonin was prevented by pretreatment with pertussis toxin. Pretreatment of cultures with 5-methoxytryptamine for 24 h reduced the subsequent inhibitory cyclic AMP response to 5-methoxytryptamine but not that to 2-iodomelatonin. Putative melatonin receptors on cultured retinal cells were labeled with 2-[¹²⁵I]iodomelatonin. Melatonin displaced specific 2-[¹²⁵I]iodomelatonin with a K _i value (0.8 n M ) similar to the EC₅₀ for inhibition of cyclic AMP formation. In contrast, 5-methoxytryptamine only inhibited 2-[¹²⁵I]iodomelatonin binding at very high concentrations ( K _i = 650 n M ). Pretreating cultured cells for 24 h with 2-iodomelatonin or melatonin, but not with 5-methoxytryptamine, reduced subsequent 2-[¹²⁵I]iodomelatonin binding. Thus, 5-methoxytryptamine appears to inhibit forskolin-stimulated cyclic AMP formation at a site distinct from the 2-iodomelatonin binding site.     

Characterization of Burkholderia pseudomallei infection and identification of novel virulence factors using a Caenorhabditis elegans host system

The environmental saphrophyte Burkholderia pseudomallei is the causative agent of melioidosis, a systemic, potentially life-threatening condition endemic to many parts of south-east Asia and northern Australia. We have used the soil nematode Caenorhabditis elegans as a model host to characterize the mechanisms by which this bacterium mounts a successful infection. We find that C. elegans is susceptible to a broad range of Burkholderia species, and that the virulence mechanisms used by this pathogen to kill nematodes may be similar to those used to infect mammals. We also find that the specific dynamics of the C. elegans-B. pseudomallei host-pathogen interaction can be highly influenced by environmental factors, and that nematode killing results at least in part from the presence of a diffusible toxin. Finally, by screening for bacterial mutants attenuated in their ability to kill C. elegans, we genetically identify several new potential virulence factors in B. pseudomallei. The use of C. elegans as a model host should greatly facilitate future investigations into how B. pseudomallei can interact with host organisms.