Insertional mutagenesis combined with an inducible filamentation phenotype reveals a conserved STE50 homologue in Cryptococcus neoformans that is required for monokaryotic fruiting and sexual reproduction

Cryptococcus neoformans typically grows in a yeast-like morphology; however, under specific conditions the fungus can produce hyphae that are either dikaryotic or monokaryotic. In this study, we developed a simple method for inducing robust monokaryotic fruiting and combined the assay with Agrobacterium tumefaciens insertional mutagenesis to screen for hyphal mutants. A C. neoformans homologue of the Saccharomyces cerevisiae STE50 gene was identified and characterized. STE50 was found to be required for sexual reproduction and monokaryotic fruiting. Ste50p has conserved SAM and RA domains, as well as two SH3 domains specific to basidiomycetous Ste50 proteins. Analysis of protein-protein interaction showed that Ste50p can interact with Ste11p and Ste20p, and epistasis experiments placed STE50 between STE20 and STE11. Genetic analysis of the role of STE50 in sexual reproduction showed that it was required for all steps, from response to pheromone to production of hyphae. Analysis of the effect of individual Ste50p domains on sexual reproduction and monokaryotic fruiting revealed domain-specific effects for both processes. This study revealed that the C. neoformans STE50 gene has both conserved and novel functions during sexual reproduction and monokaryotic fruiting, and these functions are domain-dependent.     

Optimized ferrocene-functionalized ZnO nanorods for signal amplification in electrochemical immunoassay of Escherichia coli

A novel amplified electrochemical immunoassay based on ferrocene (Fc)-functionalized ZnO nanorods (NRs) was developed in the present work. The detection antibody ((d)Ab) and Fc were immobilized onto the surface of ZnO NRs, denoted as {(d)Ab-ZnO-Fc} bioconjugates. The amount of (d)Ab and Fc in the bioconjugates was investigated using the copper reduction/bicinchoninic acid reaction (BCA protein assay) and inductive coupled plasma-atomic emission spectroscopy (ICP-AES), respectively. Greatly amplified signal was achieved in the sandwich-type immunoassay when (d)Ab and Fc linked to ZnO NRs at a proper ratio. Using Escherichia coli (E. coli) as a model antigen, the designed immunoassay showed an excellent analytical performance, and exhibited a wide dynamic response range of E. coli concentration from 10(2) to 10(6)cfu/mL with a detection limit of 50 cfu/mL (S/N=3). By introducing a pre-enrichment step, the detection of 5 cfu/10 mL E. coli in hospital sewage water was realized. This proposed signal amplification strategy was promising and could be easily extended to monitor other biorecognition events.     

Isolation and alga-inhibiting characterization of Vibrio sp. BS02 against Alexandrium tamarense

The bacterium BS02 which is closely related to the genus Vibrio sp. and capable of inhibiting the toxic dinoflagellate Alexandrium tamarense was isolated from a mangrove area in Zhangjiangkou, Fujian Province, China. The bacterium was not species-specific since it displayed varying degrees of lysing activities against eight of the eighteen algae tested. There was a close interaction between initial bacterial and A. tamarense cell densities, indicating that algal growth was prompted at low bacterial concentrations, while the number of the alga cells was reduced at high concentrations. Alga-lysing characterization of Vibrio sp. BS02 suggested that the alga-lysing substance was extracellularly produced, less than 500 in molecular weight, as well as non proteinaceous, stable under wide range of temperature and pH conditions, UV radiation, repeated freezing and thawing and heavy metal treatments. These findings suggested that BS02 could play an important role in controlling harmful algal blooms.     

BnaC.Tic40, a plastid inner membrane translocon originating from Brassica oleracea, is essential for tapetal function and microspore development in Brassica napus

Here, we describe the characteristics of a Brassica napus male sterile mutant 7365A with loss of the BnMs3 gene, which exhibits abnormal enlargement of the tapetal cells during meiosis. Later in development, the absence of the BnMs3 gene in the mutant results in a loss of the secretory function of the tapetum, as suggested by abortive callose dissolution and retarded tapetal degradation. The BnaC.Tic40 gene (equivalent to BnMs3) was isolated by a map-based cloning approach and was confirmed by genetic complementation. Sequence analyses suggested that BnaC.Tic40 originated from BolC.Tic40 on the Brassica oleracea linkage group C9, whereas its allele Bnms3 was derived from BraA.Tic40 on the Brassica rapa linkage group A10. The BnaC.Tic40 gene is highly expressed in the tapetum and encodes a putative plastid inner envelope membrane translocon, Tic40, which is localized into the chloroplast. Transmission electron microscopy (TEM) and lipid staining analyses suggested that BnaC.Tic40 is a key factor in controlling lipid accumulation in the tapetal plastids. These data indicate that BnaC.Tic40 participates in specific protein translocation across the inner envelope membrane in the tapetal plastid, which is required for tapetal development and function.     

The ratio of serum 24,25-dihydroxyvitamin D(3) to 25-hydroxyvitamin D(3) is predictive of 25-hydroxyvitamin D(3) response to vitamin D(3) supplementation

24,25-Dihydroxyvitamin D (24,25VD) is a major catabolite of 25-hydroxyvitamin D (25VD) metabolism, and may be physiologically active. Our objectives were to: (1) characterize the response of serum 24,25VD(3) to vitamin D(3) (VD(3)) supplementation; (2) test the hypothesis that a higher 24,25VD(3) to 25VD(3) ratio (24,25:25VD(3)) predicts 25VD(3) response. Serum samples (n=160) from wk 2 and wk 6 of a placebo-controlled, randomized clinical trial of VD(3) (28,000IU/wk) were analyzed for serum 24,25VD(3) and 25VD(3) by mass spectrometry. Serum 24,25VD(3) was highly correlated with 25VD(3) in placebo- and VD(3)-treated subjects at each time point (p<0.0001). At wk 2, the 24,25:25VD(3) ratio was lower with VD(3) than with placebo (p=0.035). From wk 2 to wk 6, the 24,25:25VD(3) ratio increased with the VD(3) supplement (p<0.001) but not with placebo, such that at wk 6 this ratio did not significantly differ between groups. After correcting for potential confounders, we found that 24,25:25VD(3) at wk 2 was inversely correlated to the 25VD(3) increment by wk 6 in the supplemented group (r=-0.32, p=0.02) but not the controls. There is a strong correlation between 24,25VD(3) and 25VD(3) that is only modestly affected by VD(3) supplementation. This indicates that the catabolism of 25VD(3) to 24,25VD(3) rises with increasing 25VD(3). Furthermore, the initial ratio of serum 24,25VD(3) to 25VD(3) predicted the increase in 25VD(3). The 24,25:25VD(3) ratio may therefore have clinical utility as a marker for VD(3) catabolism and a predictor of serum 25VD(3) response to VD(3) supplementation.     

Enhanced CO2 fixation by a non-photosynthetic microbial community under anaerobic conditions: optimization of electron donors

To enhance the CO(2) fixation efficiency of the non-photosynthetic microbial community (NPMC) isolated from sea water under anaerobic conditions without hydrogen, the concentration of inorganic compounds as electron donors and their ratios were optimized by response surface methodology design (RSMD). The results indicated that the CO(2) fixation efficiency of NPMC using NaNO(2), Na(2)S(2)O(3) and Na(2)S as the electron donors was increased about 90%, 75% and 207%, respectively. Additionally, there were interactions between two electron donors and three electron donors. Central composite RSMD experimentation predicted that the optimal concentration and ratios of these inorganic compounds was 1.04% NaNO(2), 1.07% Na(2)S(2)O(3) and 0.98% Na(2)S. Under these conditions, the fixed CO(2) was 139.89 mg/L, which obviously exceeded the amount prior to optimization, as well as when H(2) was used as an electron donor. The established electron donor system can effectively enhance the CO(2) fixation efficiency of NPMC without hydrogen under anaerobic conditions.     

Fiber surface characterization of old newsprint pulp deinked by combining hemicellulase with laccase-mediator system

Deinking of old newsprint (ONP) by combining hemicellulase with laccase-mediator system (LMS) was investigated, and surface chemical composition and fiber morphology changes during the deinking process were studied by electron spectroscopy for chemical analysis (ESCA), contact angle (CA), attenuated total reflectance fourier transform infrared spectrometry (ATR-FTIR), fiber quality analyzer (FQA), and environmental scanning electronic microscopy (ESEM). Results showed that, compared to the pulp deinked with hemicellulase or LMS individually, effective residual ink concentration (ERIC) was lower for the hemicellulase/LMS-deinked pulp. This indicated that there is a synergistic deinking effect between hemicellulase and LMS. It was found that O/C ratio of the fiber surface increased and the surface coverage of lignin decreased during the hemicellulase/LMS deinking process. The contact angle of the hemicellulase/LMS-deinked pulp was lower than that of pulps deinked with each individual enzyme. ESEM observations showed that more fibrils appeared on the fiber surface due to synergistic treatment.