Retinoic acid synthesis and functions in early embryonic development

Retinoic acid (RA) is a morphogen derived from retinol (vitamin A) that plays important roles in cell growth, differentiation, and organogenesis. The production of RA from retinol requires two consecutive enzymatic reactions catalyzed by different sets of dehydrogenases. The retinol is first oxidized into retinal, which is then oxidized into RA. The RA interacts with retinoic acid receptor (RAR) and retinoic acid X receptor (RXR) which then regulate the target gene expression. In this review, we have discussed the metabolism of RA and the important components of RA signaling pathway, and highlighted current understanding of the functions of RA during early embryonic development.     

Autophagy precedes apoptosis during the remodeling of silkworm larval midgut

Although several features of apoptosis and autophagy have been reported in the larval organs of Lepidoptera during metamorphosis, solid experimental evidence for autophagy is still lacking. Moreover, the role of the two processes and the nature of their relationship are still cryptic. In this study, we perform a cellular, biochemical and molecular analysis of the degeneration process that occurs in the larval midgut of Bombyx mori during larval-adult transformation, with the aim to analyze autophagy and apoptosis in cells that die under physiological conditions. We demonstrate that larval midgut degradation is due to the concerted action of the two mechanisms, which occur at different times and have different functions. Autophagy is activated from the wandering stage and reaches a high level of activity during the spinning and prepupal stages, as demonstrated by specific autophagic markers. Our data show that the process of autophagy can recycle molecules from the degenerating cells and supply nutrients to the animal during the non-feeding period. Apoptosis intervenes later. In fact, although genes encoding caspases are transcribed at the end of the larval period, the activity of these proteases is not appreciable until the second day of spinning and apoptotic features are observable from prepupal phase. The abundance of apoptotic features during the pupal phase, when the majority of the cells die, indicates that apoptosis is actually responsible for cell death and for the disappearance of larval midgut cells.     

Identification of a newly isolated erythritol-producing yeast and cloning of its erythritol reductase genes

A new erythritol-producing yeast (strain BH010) was isolated in this study. Analysis of the D1/D2 domain of the 26S rDNA sequence, the ITS/5.8S rDNA sequence, and the 18S rDNA sequence allowed the taxonomic position of strain BH010 to be discussed and it was identified and named Moniliella sp. BH010. Physiological characteristics were described. Scanning electron micrography clearly indicated that the cells were cylindrical to elliptical with an average size of 5?×?10?μm when growing in liquid medium, and that pseudohyphae and blastoconidia were observed when cultivated in agar plates. The erythritol reductase genes were cloned, sequenced, and analyzed. BLAST analysis and multiple sequence alignment demonstrated that erythritol reductase genes of Moniliella sp. BH010 shared very high homology with that of Trichosporonoides megachiliensis SNG-42 except for the presence of introns. The deduced amino acid sequences showed high homology to the aldo–keto reductase superfamily.     

Map kinase phosphatase 5 protects against sepsis-induced acute lung injury

Mitogen-activated protein kinases (MAPKs) play a critical role in inflammation. Although activation of MAPK in inflammatory cells has been studied extensively, much less is known about the inactivation of these kinases. MAPK phosphatase 5 (MKP5) is a member of the dual-specificity phosphatase family that dephosphorylates activated MAPKs. Here we report that MKP5 protects sepsis-induced acute lung injury. Mice lacking MKP5 displayed severe lung tissue damage following LPS challenge, characterized with increased neutrophil infiltration and edema compared with wild-type (WT) controls. In response to LPS, MKP5-deficient macrophages produced significantly more inflammatory factors including inflammatory cytokines, nitric oxide, and superoxide. Phosphorylation of p38 MAPK, JNK, and ERK were enhanced in MKP5-deficient macrophages upon LPS stimulation. Adoptive transfer of MKP5-deficient macrophages led to more severe lung inflammation than transfer of WT macrophages, suggesting that MKP5-deficient macrophages directly contribute to acute lung injury. Taken together, these results suggest that MKP5 is crucial to homeostatic regulation of MAPK activation in inflammatory responses.     

α-cyperone alleviates lung cell injury caused by Staphylococcus aureus via attenuation of α-hemolysin expression

In this study, we aimed to evaluate the effect of α- cyperone on S. aureus. We used a hemolysin test to examine the hemolytic activity in supernatants of S. aureus cultured with increasing concentrations of α- cyperone. In addition, we evaluated the production of α- hemolysin (Hla) by Western blotting. Real-time RT-PCR was performed to test the expression of hla (the gene encoding Hla) and agr (accessory gene regulator). Furthermore, we investigated the protective effect of α- cyperone on Hla-induced injury of A549 lung cells by live/ dead and cytotoxicity assays. We showed that in the presence of subinhibitory concentrations of α-cyperone, Hla production was markedly inhibited. Moreover, α- cyperone protected lung cells from Hla-induced injury. These findings indicate that α-cyperone is a promising inhibitor of Hla production by S. aureus and protects lung cells from this bacterium. Thus, α-cyperone may provide the basis for a new strategy to combat S. aureus pneumonia.     

Association of tuberculosis and polymorphisms in the promoter region of macrophage migration inhibitory factor (MIF) in a Southwestern China Han population

The macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that plays an important role in the pathogenesis of immune diseases. High levels of MIF have been detected in the sera of patients with tuberculosis (TB), and it has been proposed that MIF gene polymorphisms may influence the risk of developing TB. The aim of this study was to evaluate the potential relationship between functional polymorphisms of MIF and TB in a Han population from Southwestern China. TB patients (n=215) and healthy unrelated controls (n=245) were recruited for this study. Genomic DNA was isolated from all the participants. The MIF-173 G/C SNP was genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The MIF-794 CATT(5-8) microsatellite was evaluated by direct sequencing of the subsequent PCR products. Association analysis of the two polymorphisms showed that the frequency of -173 (GC+CC) in TB patients and controls was 49.3% and 31.4%, respectively, which was statistically significant (OR=2.12, 95% CI=1.45-3.10, P<0.001); the frequencies of -794 (7/X+8/X) were 56.7% and 45.3%, respectively, also statistically significant between the TB and healthy controls (OR=1.58, 95% CI=1.10-2.29, P=0.015). In summary, Genetic variation in the MIF gene is closely associated with tuberculosis. Both the 173 (GC+CC) SNP and -794 (7/X+8/X) microsatellite increased the risk of Chinese Han developing TB.     

The structural characteristics of human preprotein translocase of the inner mitochondrial membrane Tim23: implications for its physiological activities

The preprotein translocase of the inner mitochondrial membrane (TIM23 complex) is the main entry gate for proteins of the matrix and the inner membrane. Tim23 forms a pore for preprotein transportation in TIM23 complex, which spans the inner membrane with transmembrane segments and exposes a hydrophilic domain in the intermembrane space. In this study, we expressed and purified the intermembrane space (IMS) domain of human Tim23 (Tim23(IMS)). The far-UV CD spectra of Tim23(IMS) in native and denatured states revealed that the protein has a limited secondary structure and a not well-defined tertiary packing. Its Stokes radius was larger than both its expected size as a folded globular protein and the size determined by size exclusion chromatography. A large increase in 8-anilino-1-naphthalene-sulfonate (ANS) fluorescence (>50-fold) was observed, indicating that hydrophobic clusters are exposed at its surface. And GlobPlot/DisEMBL program predicted that the protein is in a loose folding state. We therefore conclude that, the non-bound hydrophilic domain of the human Tim23 is in a molten globule configuration with marginal stability. Furthermore, size exclusion chromatography and sedimentation equilibrium analysis showed that Tim23(IMS) exists as a dimer. And the results, showed by ANS binding and fluorescence quenching, indicated that a pH-dependent conformational change of Tim23(IMS) occurs, and at pH 4 and 3, it forms a compact structure.     

Study on the immune enhancement of different immunoadjuvants used in the pentavalent vaccine for turbots

In this study, we investigated the immune enhancing effects of different adjuvants used in a pentavalent vaccine for turbots. The pentavalent vaccine consisted of inactive bacterial cells from five common pathogenic strains (Vibrio anguillarum, Vibrio scophtalmi, Edwardsiella tarda, Vibrio harveyi and Vibrio alginolyticus) and the adjuvants were astragalus polysaccharides (APS), propolis, and the Freund’s complete adjuvant (FCA). Turbots were immunized with the pentavalent vaccine alone or with one of the adjuvants, and the immune efficiency was evaluated by measuring the activities of lysozyme (LSZ) and superoxide dismutase (SOD), and serum antibody titers. Fish were also challenged with the pathogens after immunization and the relative percent survival (RPS) was assessed. Our results showed that APS, propolis, and FCA had significant immune-enhancing effects on turbots as shown by the higher titers of antibodies against the pathogens, increased LSZ and SOD activities, and enhanced RPS after challenge with pathogens. Among the three adjuvants, FCA had the most significant immune synergistic effects with the vaccine, and APS and propolis had lower and similar immune synergies.