Kinetic characterization and thermostability of C. elegans cytoplasmic and mitochondrial malate dehydrogenases.

Malate dehydrogenase (MDH) catalyzes the conversion of NAD+ and malate to NADH and oxaloacetate in the citric acid cycle. Eukaryotes have one MDH isozyme that is imported into the mitochondria and one in the cytoplasm. We overexpressed and purified Caenorhabditis elegans cytoplasmic MDH-1 and mitochondrial MDH-2 in E. coli. Our goal was to compare the kinetic and structural properties of these enzymes because C. elegans can survive adverse environmental conditions, such as lack of food and elevated temperatures. In steady-state enzyme kinetics assays, we measured KM values for oxaloacetate of 54 and 52 µM and KM values for NADH of 61 and 107 µM for MDH-1 and MDH-2, respectively. We partially purified endogenous MDH-1 and MDH-2 from a mixed population of worms and separated them using anion exchange chromatography. Both endogenous enzymes had a KM for oxaloacetate similar to that of the corresponding recombinant enzyme. Recombinant MDH-1 and MDH-2 had maximum activity at 40 °C and 35 °C, respectively. In a thermotolerance assay, MDH-1 was much more thermostable than MDH-2. Protein homology modeling predicted that MDH-1 had more intersubunit salt-bridges than mammalian MDH1 enzymes, and these ionic interactions may contribute to its thermostability. In contrast, the MDH-2 homology model predicted fewer intersubunit ionic interactions compared to mammalian MDH2 enzymes. These results suggest that the increased stability of MDH-1 may facilitate its ability to remain active in adverse environmental conditions. In contrast, MDH-2 may use other strategies, such as protein binding partners, to function under similar conditions.

Evidence Base Update of Psychosocial Treatments for Self-Injurious Thoughts and Behaviors in Youth.

The current review provides an evidence base update of psychosocial treatments for self-injurious thoughts and behaviors (SITBs) in youth. A systematic search was conducted of 2 major scientific databases (PsycInfo and PubMed) and ClinicalTrials.gov for relevant randomized controlled trials (RCTs) published prior to June 2018. The search identified 26 RCTs examining interventions for SITBs in youth: 17 were included in the 2015 review and 9 trials were new to this update. The biggest change since the prior review was the evaluation of Dialectical Behavior Therapy for adolescents (DBT-A) as the first Level 1: Well-established intervention for reducing deliberate self-harm (composite of nonsuicidal and suicidal self-injury) and suicide ideation in youth and Level 2: Probably efficacious for reducing nonsuicidal self-injury and suicide attempts. Five other interventions were rated as Level 2: Probably efficacious for reducing SITBs in youth, with the new addition of Integrated Family Therapy. This evidence base update indicates that there are a few promising treatments for reducing SITBs in youth. Efficacious interventions typically include a significant family or parent training component as well as skills training (e.g., emotion regulation skills). Aside from DBT-A, few treatments have been examined in more than one RCT. Given that replication by independent research groups is needed to evaluate an intervention as Well-established, future research should focus on replicating the five promising interventions currently evaluated as Probably efficacious. In addition, an important future direction is to develop brief efficacious interventions that may be scalable to reach large numbers of youth.

Reflections On A Quality Journey.

Going for the gold unites staff and empowers them to make a difference.

Microform-related community patterns of methane-cycling microbes in boreal Sphagnum bogs are site specific.

Vegetation and water table are important regulators of methane emission in peatlands. Microform variation encompasses these factors in small-scale topographic gradients of dry hummocks, intermediate lawns and wet hollows. We examined methane production and oxidization among microforms in four boreal bogs that showed more variation of vegetation within a bog with microform than between the bogs. Potential methane production was low and differed among bogs but not consistently with microform. Methane oxidation followed water table position with microform, showing higher rates closer to surface in lawns and hollows than in hummocks. Methanogen community, analysed by mcrA terminal restriction fragment length polymorphism and dominated by Methanoregulaceae or 'Methanoflorentaceae', varied strongly with bog. The extent of microform-related variation of methanogens depended on the bog. Methanotrophs identified as Methylocystis spp. in pmoA denaturing gradient gel electrophoresis similarly showed effect of bog, and microform patterns were stronger within individual bogs. Our results suggest that methane-cycling microbes in boreal Sphagnum bogs with seemingly uniform environmental conditions may show strong site-dependent variation. The bog-intrinsic factor may be related to carbon availability but contrary to expectations appears to be unrelated to current surface vegetation, calling attention to the origin of carbon substrates for microbes in bogs.