Aureolysin of Staphylococcus warneri M accelerates its proteolytic cascade,and participates in biofilm formation

The aureolysin (Aur) gene of S. warneri M (aurWM) was cloned and sequenced. Analyses of the aurWM-inactivated mutant (S. warneri Mau) suggested that AurWM was probably associated with efficient processing of the PROM protease (homolog of V8/SspA serine protease), whereas considerable amount of mature-PROC protease (homolog of SspB cysteine protease) accumulated without AurWM. Additionally, AurWM appeared to affect biofilm formation in an uncertain suppressive way.     

Combined brain‐derived neurotrophic factor with extinction training alleviate impaired fear extinction in an animal model of post‐traumatic stress disorder

Impaired fear memory extinction (Ext) is one of the hallmark symptoms of post‐traumatic stress disorder (PTSD). However, since the precise mechanism of impaired Ext remains unknown, effective interventions have not yet been established. Recently, hippocampal‐prefrontal brain‐derived neurotrophic factor (BDNF) activity was shown to be crucial for Ext in naïve rats. We therefore examined whether decreased hippocampal‐prefrontal BDNF activity is also involved in the Ext of rats subjected to a single prolonged stress (SPS) as a model of PTSD. BDNF levels were measured by enzyme‐linked immunosorbent assay (ELISA), and phosphorylation of TrkB was measured by immunohistochemistry in the hippocampus and medial prefrontal cortex (mPFC) of SPS rats. We also examined whether BDNF infusion into the ventral mPFC or hippocampus alleviated the impaired Ext of SPS rats in the contextual fear conditioning paradigm. SPS significantly decreased the levels of BDNF in both the hippocampus and mPFC and TrkB phosphorylation in the ventral mPFC. Infusion of BDNF 24 hours after conditioning in the infralimbic cortex (ILC), but not the prelimbic cortex (PLC) nor hippocampus, alleviated the impairment of Ext. Since amelioration of impaired Ext by BDNF infusion did not occur without extinction training, it seems the two interventions must occur consecutively to alleviate impaired Ext. Additionally, BDNF infusion markedly increased TrkB phosphorylation in the ILC of SPS rats. These findings suggest that decreased BDNF signal transduction might be involved in the impaired Ext of SPS rats, and that activation of the BDNF‐TrkB signal might be a novel therapeutic strategy for the impaired Ext by stress.     

Characterization of Arabidopsis decapping proteins AtDCP1 and AtDCP2, which are essential for post-embryonic development

Although decapping is an important process in eukaryotic mRNA turnover, little is known about this process in plants. Here, we identified Arabidopsis thaliana decapping proteins AtDCP1 and AtDCP2 and showed that (I) AtDCP2 is an active decapping enzyme, (II) AtDCP1 interacts with itself, (III) AtDCP1 and AtDCP2 are localized to cytoplasmic foci (putative Arabidopsis processing body), and (IV) AtDCP1 and AtDCP2 are essential for post-embryonic development. Our findings provide new insights into the role of decapping-dependent mRNA turnover.     

Serotonin differentially regulates short- and long-term prediction of rewards in the ventral and dorsal striatum

Background

The ability to select an action by considering both delays and amount of reward outcome is critical for maximizing long-term benefits. Although previous animal experiments on impulsivity have suggested a role of serotonin in behaviors requiring prediction of delayed rewards, the underlying neural mechanism is unclear.

Methodology/Principal Findings

To elucidate the role of serotonin in the evaluation of delayed rewards, we performed a functional brain imaging experiment in which subjects chose small-immediate or large-delayed liquid rewards under dietary regulation of tryptophan, a precursor of serotonin. A model-based analysis revealed that the activity of the ventral part of the striatum was correlated with reward prediction at shorter time scales, and this correlated activity was stronger at low serotonin levels. By contrast, the activity of the dorsal part of the striatum was correlated with reward prediction at longer time scales, and this correlated activity was stronger at high serotonin levels.

Conclusions/Significance

Our results suggest that serotonin controls the time scale of reward prediction by differentially regulating activities within the striatum.     

Rapid SNP diagnostics using asymmetric isothermal amplification and a new mismatch-suppression technology

We developed a rapid single nucleotide polymorphism (SNP) detection system named smart amplification process version 2 (SMAP 2). Because DNA amplification only occurred with a perfect primer match, amplification alone was sufficient to identify the target allele. To achieve the requisite fidelity to support this claim, we used two new and complementary approaches to suppress exponential background DNA amplification that resulted from mispriming events. SMAP 2 is isothermal and achieved SNP detection from whole human blood in 30 min when performed with a new DNA polymerase that was cloned and isolated from Alicyclobacillus acidocaldarius (Aac pol). Furthermore, to assist the scientific community in configuring SMAP 2 assays, we developed software specific for SMAP 2 primer design. With these new tools, a high-precision and rapid DNA amplification technology becomes available to aid in pharmacogenomic research and molecular-diagnostics applications.     

Heterozygous loss of Zbtb38 leads to early embryonic lethality via the suppression of Nanog and Sox2 expression

ObjectivesMammalian DNA methyltransferases are essential to re‐establish global DNA methylation patterns during implantation, which is critical for transmitting epigenetic information to the next generation. In contrast, the significance of methyl‐CpG binding proteins (MBPs) that bind methylated CpG remains almost unknown at this stage. We previously demonstrated that Zbtb38 (also known as CIBZ)—a zinc finger type of MBP—is required for mouse embryonic stem (ES) cell proliferation by positively regulating Nanog expression. However, the physiological function of Zbtb38 in vivo remains unclear.Materials and MethodsThis study used the Cre‐loxP system to generate conditional Zbtb38 knockout mice. Cell proliferation and apoptosis were studied by immunofluorescence staining. Quantitative real‐time PCR, immunoblotting and immunofluorescence were performed to investigate the molecular mechanisms.ResultsGermline loss of the Zbtb38 single allele resulted in decreased epiblast cell proliferation and increased apoptosis shortly after implantation, leading to early embryonic lethality. Heterozygous loss of Zbtb38 reduced the expression of Nanog, Sox2, and the genes responsible for epiblast proliferation, differentiation, and cell viability. Although this early lethal phenotype, Zbtb38 is dispensable for ES cell establishment and identity.ConclusionsThese findings indicate that Zbtb38 is essential for early embryonic development via the suppression of Nanog and Sox2 expression.

Heterozygous loss of Zbtb38 leads to aberrant epiblast cell proliferation and apoptosis shortly after implantation. Heterozygous loss of Zbtb38 reduced the expression of Nanog and Sox2 in ICM and epiblast.     

Mutagenic and nonmutagenic bypass of DNA lesions by Drosophila DNA polymerases dpoleta and dpoliota

cDNA sequences were identified and isolated that encode Drosophila homologues of human Rad30A and Rad30B called drad30A and drad30B. Here we show that the C-terminal-truncated forms of the drad30A and drad30B gene products, designated dpoletaDeltaC and dpoliotaDeltaC, respectively, exhibit DNA polymerase activity. dpoletaDeltaC and dpoliotaDeltaC efficiently bypass a cis-syn-cyclobutane thymine-thymine (TT) dimer in a mostly error-free manner. dpoletaDeltaC shows limited ability to bypass a 6-4-photoproduct ((6-4)PP) at thymine-thymine (TT-(6-4)PP) or at thymine-cytosine (TC-(6-4)PP) in an error-prone manner. dpoliotaDeltaC scarcely bypasses these lesions. Thus, the fidelity of translesion synthesis depends on the identity of the lesion and on the polymerase. The human XPV gene product, hpoleta, bypasses cis-syn-cyclobutane thymine-thymine dimer efficiently in a mostly error-free manner but does not bypass TT-(6-4)PP, whereas Escherichia coli DNA polymerase V (UmuD'(2)C complex) bypasses both lesions, especially TT-(6-4)PP, in an error-prone manner (Tang, M., Pham, P., Shen, X., Taylor, J. S., O'Donnell, M., Woodgate, R., and Goodman, M. F. (2000) Nature 404, 1014-1018). Both dpoletaDeltaC and DNA polymerase V preferentially incorporate GA opposite TT-(6-4)PP. The chemical structure of the lesions and the similarity in the nucleotides incorporated suggest that structural information in the altered bases contribute to nucleotide selection during incorporation opposite these lesions by these polymerases.     

Polyamine cytotoxicity in the presence of bovine serum amine oxidase

The toxicity of extracellular spermine, determined in the presence of fetal calf serum, was studied using three cell lines: FM3A, L1210, and NIH3T3 cells. Amine oxidase in fetal calf serum produces aminodialdehyde generating acrolein spontaneously, H(2)O(2), and ammonia from spermine. Spermine toxicity was prevented by aldehyde dehydrogenase, but not by catalase. Similar concentrations of spermine and acrolein were needed to produce toxicity. Other aldehydes (formaldehyde, acetaldehyde, and propionaldehyde) and hydrogen peroxide were less toxic than acrolein. Spermidine and 3-aminopropanal, which produces acrolein, also exhibited severe cytotoxicity. The degree of cytotoxicity of spermine, spermidine, and 3-aminopropanal was nearly parallel with the amount of acrolein produced from each compound. Thus, it was deduced that acrolein is a major toxic compound produced from polyamines (spermine and spermidine) by amine oxidase.