Psb27 has been identified as a lumenal protein associated with photosystem II (PSII). To gain insight into the function of Psb27, we isolated a mutant Arabidopsis plant with a loss of psb27 function. The quantity of PSII complexes and electron transfer within PSII remained largely unaffected in the psb27 mutant. Our results also showed that under high-light-illumination, PSII activity and the content of the PSII reaction center protein D1 decreased more significantly in the psb27 mutant than in wild-type (WT) plant. Treatment of leaves with a chloroplast protein synthesis inhibitor resulted in similar light-induced PSII inactivation levels and D1 protein degradation rates in the WT and psb27 mutant plants. Recovery of PSII activity after photoinhibition was delayed in the psb27 mutant, suggesting that Psb27 is required for efficient recovery of the photodamaged PSII complex. Overall, these results demonstrated that Psb27 in Arabidopsis is not essential for oxygenic photosynthesis and PSII formation. Instead, our results provide evidence for the involvement of this lumenal protein in the recovery process of PSII.

BackgroundUrinary interleukin-18 and cystatin-C are suggested to be biomarkers for predicting acute kidney injury (AKI). The aims of this study are to examine whether the urinary concentrations of interleukin-18 and cystatin-C vary with gestational age and other factors in non-AKI control neonates, and to determine whether urinary interleukin-18 and cystatin-C can predict AKI development in non-septic critically ill neonates, independently of potential confounders.MethodsWe enrolled 62 non-septic critically ill neonates. Urine was collected every 48–72 h during the first 10 days of life.ResultsUrinary concentration of cystatin-C, but not interleukin-18, decreased with increasing gestational age and body weight, but not with increasing postnatal age in non-AKI control neonates. Both urinary interleukin-18 and cystatin-C were associated with AKI, even after controlling for gestational and postnatal age, birth weight, gender, Apgar score and the score for neonatal acute physiology in non-septic critically ill neonates. Urinary interleukin-18 and cystatin-C had odds ratios of 2.27 and 2.07, and achieved the area under-the-receiver-operating-characteristic curve of 0.72 and 0.92, respectively, for predicting AKI.ConclusionsThe urinary concentration of cystatin-C, but not interleukin-18, may decrease with increasing renal maturity. Both urinary interleukin-18 and cystatin-C are independently predictive of AKI in non-septic critically ill neonates.

A cultivation-based approach was employed to compare the culturable actinobacterial diversity associated with five marine sponge species (Craniella australiensis, Halichondria rugosa, Reniochalina sp., Sponge sp., and Stelletta tenuis). The phylogenetic affiliation of the actinobacterial isolates was assessed by 16S rDNA-RFLP analysis. A total of 181 actinobacterial strains were isolated using five different culture media (denoted as M1-M5). The type of medium exhibited significant effects on the number of actinobacteria recovered, with the highest number of isolates on M3 (63 isolates) and the lowest on M1 (12 isolates). The genera isolated were also different, with the recovery of three genera on M2 and M3, and only a single genus on M1. The number of actinobacteria isolated from the five sponge species was significantly different, with a count of 83, 36, 30, 17, and 15 isolates from S. tenuis, H. rugosa, Sponge sp., Reniochalina sp., and C. australiensis, respectively. M3 was the best isolation medium for recovery of actinobacteria from S. tenuis, H. rugosa, and Sponge sp., while no specific medium preference was observed for the recovery of actinobacteria from Reniochalina sp., and C. australiensis. The RFLP fingerprinting of 16S rDNA genes digested with HhaI revealed six different patterns, in which 16 representative 16S rDNAs were fully sequenced. Phylogenetic analysis indicated that 12 strains belong to the group Streptomyces, three strains belong to Pseudonocardia, and one strain belongs to Nocardia. Two strains C14 (from C. australiensis) and N13 (from Sponge sp.) have only 96.26% and 96.27% similarity to earlier published sequences, and are therefore potential candidates for new species. The highest diversity of three actinobacteria genera was obtained from Sponge sp., though the number of isolates was low. Two genera of actinobacteria, Streptomyces, and Pseudonocardia, were isolated from both S. tenuis and C. australiensis. Only the genus of Streptomyces was isolated from H. rugosa and Reniochalina sp. Sponge species have been demonstrated here to vary as sources of culturable actinobacterial diversity, and the methods for sampling such diversity presented may be useful for improved sampling of such diversity.

We demonstrated that a significant volume of H(2) gas could be photobiologically produced by a marine green alga Platymonas subcordiformis when an uncoupler of photophosphorylation, carbonyl cyanide m-chlorophenylhydrazone (CCCP), was added after 32 h of anaerobic dark incubation, whereas a negligible volume of H(2) gas was produced without CCCP. The role of CCCP in enhancing photobiological H(2) production was delineated. CCCP as an ADRY agent (agent accelerating the deactivation reactions of water-splitting enzyme system Y) rapidly inhibited the photosystem II (PSII) activity of P. subcordiformis cells, resulting in a markedly decline in the coupled oxygen evolution. The mitochondrial oxidative respiration was only slightly inactivated by CCCP, which depleted O(2) in the light. As a result, anaerobiosis during the stage of photobiological H(2) evolution was established, preventing severe O(2) inactivation of the reversible hydrogenase in P. subcordiformis. The uncoupling effect of CCCP accelerates electron transfer from water due to a disruption of the proton motive force and release of DeltapH across the thylakoid membrane and thus enhances the accessibility of electron and H(+) to hydrogenase. The electrons for hydrogen photoevolution are mainly from the photolysis of water (90%). Upon the addition of CCCP, Chl a/b ratio increased, which implies a decrease in the light-harvesting PSII antennae or an increase in PSII/PSI ratio, possibly resulting in higher efficiency of utilization of light energy. The enhancement of H(2) evolution by the addition of CCCP is mostly due to the combination of the above three mechanisms. However, the disruption of the proton gradient across the thylakoid membrane may prevent a sustained photobiological H(2) evolution due to a shortfall of ATP generation essential for the maintenance and repair functions of the cells.

Marine sponges (Porifera) possess an extraordinary diversity of bioactive metabolites for new drug discovery and development. In vitro cultivation of sponge cells in a bioreactor system is very attractive for the sustainable production of sponge-derived bioactive metabolites; however, it is still a challenging task. The recent establishment of sponge primmorphs, multicellular aggregates from dissociated mixed-cell population (MCP), has been widely acknowledged to hold great promise for cultivation in vitro. Here we present a new method to establish an in vitro sponge primmorph culture from archaeocyte-dominant cell population (ADCP) enriched by a Ficoll gradient, rather than a mixed-cell population (MCP). Our rationale is based upon the totipotency (the ability of a cell to differentiate into other cell types) of archaeocyte cells and the different biological functions of various sponge cell types. A sponge, Hymeniacidon perleve collected from the China Yellow Sea was used as a model system for this investigation. Distinct dynamics of primmorph formation were observed while significant increases in DNA synthesis, cell proliferation (up to threefold), and cell growth (up to fourfold) were achieved. Furthermore, a timedependent spiculogenesis was clearly demonstrated in our longterm culture, indicating high metabolic activity of primmorphs from the ADCP. This new method represents an important step forward to advance sponge cell culture in vitro that may lead to commercial exploitation of spongederived drugs. B

A marine green microalga, Platymonas subcordiformis, photo-synthetically generates H(2) but only transiently at a negligible yield when exposed to light after a period of dark anaerobic incubation. A protonophore uncoupler, carbonyl cyanide m-chlorophenylhrazone (CCCP) significantly increased the yield of H(2) photo-production. CCCP optimally at 15 microM gave 4.9 ml H(2) after 8 h light irradiation in 1 l algal cell culture at 1.8 x 10(6) cells ml(-1). The H(2) yield at 15 microM CCCP was increased by 240-fold when compared to the control. This improvement may be by CCCP disrupting the proton motive force thus facilitating proton transfer across the thylakoidal membrane.

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The role of Toll-like receptor (TLR) 2 in modulating allergy-induced asthma is contradictory. We investigated the effect of TLR2 gene deletion in a murine model of ovalbumin (OVA)-challenged asthma. TLR2 wild-type (TLR2(+/+)) and TLR2-deficient (TLR2(-/-)) mice were sensitized to soluble OVA antigens and challenged with OVA, and the extent of allergic airways disease was analyzed in both groups of mice at day 8 after being challenged with OVA aerosol. At day 8 post-OVA, TLR2(-/-) mice exhibited significantly lower airway hyperresponsiveness, airway inflammation, and whole lung T-helper type 2 (Th2) cytokine levels compared with the TLR2(+/+) group. TLR2 deletion also significantly reduced mucus cell metaplasia and peribronchial fibrosis in mice at day 8 after challenged by OVA. The p38/AKT/nuclear factor kappaB (NF-kappaB) p65 and phosphate extracellular signal-regulated kinase (ERK)/p38/AKT was decreased in TLR2(-/-) mouse lungs. Thus, during OVA asthma in mice, TLR2 is a major contributor to the maintenance of the adaptive Th2-cytokine-driven inflammatory disorder and ERK/p38 as well as AKT/NF-κB playing a role in it.