Production of human caseinomacropeptide in recombinant Saccharomyces cerevisiae and Pichia pastoris

Caseinomacropeptide is a polypeptide of 64 amino acid residues (106–169) derived from the C-terminal part of the mammalian milk k-casein. This macropeptide has various biological activities and is used as a functional food ingredient as well as a pharmaceutical compound. The gene encoding the human caseinomacropeptide (hCMP) was synthesized and expressed with an α-factor secretion signal in the two yeast strains, Saccharomyces cerevisiae and Pichia pastoris. The complete polypeptide of the recombinant hCMP was produced and secreted in a culture medium by both the strains, but the highest production was observed in S. cerevisiae with a galactose-inducible promoter. In a fed-batch bioreactor culture, 2.5 g/l of the recombinant hCMP was obtained from the S. cerevisiae at 97 h.     

Oxidative stress-dependent structural and functional switching of a human 2-Cys peroxiredoxin isotype II that enhances HeLa cell resistance to H2O2-induced cell death

Although biochemical properties of 2-Cys peroxiredoxins (Prxs) have been extensively studied, their real physiological functions in higher eukaryotic cells remain obscure and certainly warrant further study. Here we demonstrated that human (h) PrxII, a cytosolic isotype of human 2-Cys Prx, has dual functions as a peroxidase and a molecular chaperone, and that these different functions are closely associated with its adoption of distinct protein structures. Upon exposure to oxidative stress, hPrxII assumes a high molecular weight complex structure that has a highly efficient chaperone function. However, the subsequent removal of stressors induces the dissociation of this protein structure into low molecular weight proteins and triggers a chaperone-to-peroxidase functional switch. The formation of a high molecular weight hPrxII complex depends on the hyperoxidation of its N-terminal peroxidatic Cys residue as well as on its C-terminal domain, which contains a "YF motif" that is exclusively found in eukaryotic 2-Cys Prxs. A C-terminally truncated hPrxII exists as low and oligomeric protein species and does not respond to oxidative stress. Moreover, this C-terminal deletion of hPrxII converted it from an oxidation-sensitive to a hyperoxidation-resistant form of peroxidase. When functioning as a chaperone, hPrxII protects HeLa cells from H(2)O(2)-induced cell death, as measured by a terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling assay and fluorescence-activated cell sorting analysis.     

Integration of flowering signals in winter-annual Arabidopsis

Photoperiod is the primary environmental factor affecting flowering time in rapid-cycling accessions of Arabidopsis (Arabidopsis thaliana). Winter-annual Arabidopsis, in contrast, have both a photoperiod and a vernalization requirement for rapid flowering. In winter annuals, high levels of the floral inhibitor FLC (FLOWERING LOCUS C) suppress flowering prior to vernalization. FLC acts to delay flowering, in part, by suppressing expression of the floral promoter SOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1). Vernalization leads to a permanent epigenetic suppression of FLC. To investigate how winter-annual accessions integrate signals from the photoperiod and vernalization pathways, we have examined activation-tagged alleles of FT and the FT homolog, TSF (TWIN SISTER OF FT), in a winter-annual background. Activation of FT or TSF strongly suppresses the FLC-mediated late-flowering phenotype of winter annuals; however, FT and TSF overexpression does not affect FLC mRNA levels. Rather, FT and TSF bypass the block to flowering created by FLC by activating SOC1 expression. We have also found that FLC acts as a dosage-dependent inhibitor of FT expression. Thus, the integration of flowering signals from the photoperiod and vernalization pathways occurs, at least in part, through the regulation of FT, TSF, and SOC1.     

Occurrence and distribution of the grape rust mite Calepitrimerus vitis (Nalepa, 1905) in Korea

The grape rust mite, Calepitrimerus vitis, was identified from grapevines firstly in Korea. In the spring of 2011, symptoms characterized by the retarded growth of young shoots and flower buds in the grapevine were reported by local farmers in Hwaseong, Gyeonggi province of Korea. A large number of the small, white, and longitudinal mites were observed both on the twig surfaces and the overwintering buds. The mite was identified as Calepitrimerus vitis (Nalepa) (Acari: Eriophyidae) by morphological observations under both a microscope and scanning electron microscope (SEM). Nationwide surveys in 2011–2012 were conducted to figure out the distribution of the mite, revealing that the mite was widely distributed in the grape production area in Korea both in greenhouse and in open field vineyards. Interestingly, the mite density was much higher in Hwaseong, a middle-west coast of Korea, with several hundred mites per overwintering bud. However, no significant damage was observed from the sprouting season to the harvest time, except for the retarded growth of shoot and flower buds in the early season. The morphological characteristics of C. vitis with SEM micrographs and the survey results in major grape production areas in Korea are reported herein.     

Bacterial inactivation of wound infection in a human skin model by liquid-phase discharge plasma

Background

We investigate disinfection of a reconstructed human skin model contaminated with biofilm-formative Staphylococcus aureus employing plasma discharge in liquid.

Principal Findings

We observed statistically significant 3.83-log10 (p<0.001) and 1.59-log10 (p<0.05) decreases in colony forming units of adherent S. aureus bacteria and 24 h S. aureus biofilm culture with plasma treatment. Plasma treatment was associated with minimal changes in histological morphology and tissue viability determined by means of MTT assay. Spectral analysis of the plasma discharge indicated the presence of highly reactive atomic oxygen radicals (777 nm and 844 nm) and OH bands in the UV region. The contribution of these and other plasma-generated agents and physical conditions to the reduction in bacterial load are discussed.

Conclusions

These findings demonstrate the potential of liquid plasma treatment as a potential adjunct therapy for chronic wounds.