Arabidopsis VTC2 encodes a GDP-L-galactose phosphorylase, the last unknown enzyme in the Smirnoff-Wheeler pathway to ascorbic acid in plants

The first committed step in the biosynthesis of L-ascorbate from D-glucose in plants requires conversion of GDP-L-galactose to L-galactose 1-phosphate by a previously unidentified enzyme. Here we show that the protein encoded by VTC2, a gene mutated in vitamin C-deficient Arabidopsis thaliana strains, is a member of the GalT/Apa1 branch of the histidine triad protein superfamily that catalyzes the conversion of GDP-L-galactose to L-galactose 1-phosphate in a reaction that consumes inorganic phosphate and produces GDP. In characterizing recombinant VTC2 from A. thaliana as a specific GDP-L-galactose/GDP-D-glucose phosphorylase, we conclude that enzymes catalyzing each of the ten steps of the Smirnoff-Wheeler pathway from glucose to ascorbate have been identified. Finally, we identify VTC2 homologs in plants, invertebrates, and vertebrates, suggesting that a similar reaction is used widely in nature.     

Doxorubicin-induced ovarian toxicity

Background  

Young cancer patients may occasionally face infertility and premature gonadal failure. Apart from its direct effect on follicles and oocytes, chemotherapy may induce ovarian toxicity via an impact on the entire ovary. The role of doxorubicin in potential ovarian failure remains obscure. Our intention was to elucidate doxorubicin-related toxicity within ovaries.     

Reliability of video taped interviews with children suspected of being sexually abused.

OBJECTIVE--To determine the reliability of judgments about the likelihood of child sexual abuse based only on video recorded interviews. DESIGN--Blinded rating of likelihood of abuse by seven professional groups and comparison with consensus rating. SETTING--Child and adolescent psychiatry centre. SUBJECTS--Four people from each of seven professional disciplines: specialist psychiatrists, general psychiatrists, experimental psychologists, trainee social workers, trainee clinical psychologists, lawyers, and police. MAIN OUTCOME MEASURE--Rating of 12 recorded interviews. RESULTS--Agreement between the consensus panel and professional groups was 83% (151/183) for high likelihood cases (seven cases) and 89% (118/132) for low likelihood cases (five). Specialist psychiatrists and the police were better able to identify high likelihood cases than were other groups with less experience of interviewing sexually abused children (91% (48/53) v 79% (102/129); p = 0.05). CONCLUSIONS--Raters could accurately distinguish children with low likelihood of abuse on interview evidence alone, but those with more experience of dealing with sexual abuse were better at identifying high likelihood cases.     

Tuning DO:DM Ratios Modulates MHC Class II Immunopeptidomes

Major histocompatibility complex class II (MHC-II) antigen presentation underlies a wide range of immune responses in health and disease. However, how MHC-II antigen presentation is regulated by the peptide-loading catalyst HLA-DM (DM), its associated modulator, HLA-DO (DO), is incompletely understood. This is due largely to technical limitations: model antigen-presenting cell (APC) systems that express these MHC-II peptidome regulators at physiologically variable levels have not been described. Likewise, computational prediction tools that account for DO and DM activities are not presently available. To address these gaps, we created a panel of single MHC-II allele, HLA-DR4-expressing APC lines that cover a wide range of DO:DM ratio states. Using a combined immunopeptidomic and proteomic discovery strategy, we measured the effects DO:DM ratios have on peptide presentation by surveying over 10,000 unique DR4-presented peptides. The resulting data provide insight into peptide characteristics that influence their presentation with increasing DO:DM ratios. These include DM sensitivity, peptide abundance, binding affinity and motif, peptide length, and choice of binding register along the source protein. These findings have implications for designing improved HLA-II prediction algorithms and research strategies for dissecting the variety of functions that different APCs serve in the body.     

Photo‐switchable microbial fuel‐cells

Regulation of Bio‐systems in a clean, simple, and efficient way is important for the design of smart bio‐interfaces and bioelectronic devices. Light as a non‐invasive mean to control the activity of a protein enables spatial and temporal control far superior to other chemical and physical methods. The ability to regulate the activity of a catalytic enzyme in a biofuel‐cell reduces the waste of resources and energy and turns the fuel‐cell into a smart and more efficient device for power generation. Here we present a microbial‐fuel‐cell based on a surface displayed, photo‐switchable alcohol dehydrogenase. The enzyme was modified near the active site using non‐canonical amino acids and a small photo‐reactive molecule, which enables reversible control of enzymatic activity. Depending on the modification site, the enzyme exhibits reversible behavior upon irradiation with UV and visible light, in both biochemical, and electrochemical assays. The change observed in power output of a microbial fuel cell utilizing the modified enzyme was almost five‐fold, between inactive and active states.