Crystal structure of the carboxyltransferase subunit of the bacterial sodium ion pump glutaconyl-coenzyme A decarboxylase

Glutaconyl-CoA decarboxylase is a biotin-dependent ion pump whereby the free energy of the glutaconyl-CoA decarboxylation to crotonyl-CoA drives the electrogenic transport of sodium ions from the cytoplasm into the periplasm. Here we present the crystal structure of the decarboxylase subunit (Gcdalpha) from Acidaminococcus fermentans and its complex with glutaconyl-CoA. The active sites of the dimeric Gcdalpha lie at the two interfaces between the mono mers, whereas the N-terminal domain provides the glutaconyl-CoA-binding site and the C-terminal domain binds the biotinyllysine moiety. The Gcdalpha catalyses the transfer of carbon dioxide from glutaconyl-CoA to a biotin carrier (Gcdgamma) that subsequently is decarboxylated by the carboxybiotin decarboxylation site within the actual Na(+) pump (Gcdbeta). The analysis of the active site lead to a novel mechanism for the biotin-dependent carboxy transfer whereby biotin acts as general acid. Furthermore, we propose a holoenzyme assembly in which the water-filled central channel of the Gcdalpha dimer lies co-axial with the ion channel (Gcdbeta). The central channel is blocked by arginines against passage of sodium ions which might enter the central channel through two side channels.     

Concurrent training: a meta-analysis examining interference of aerobic and resistance exercises

The primary objective of this investigation was to identify which components of endurance training (e.g., modality, duration, frequency) are detrimental to resistance training outcomes. A meta-analysis of 21 studies was performed with a total of 422 effect sizes (ESs). Criteria for the study included were (a) compare strength training alone to strength plus endurance training (concurrent) or to compare combinations of concurrent training; (b) the outcome measures include at least one measure of strength, power, or hypertrophy; and (c) the data necessary to calculate ESs must be included or available. The mean ES for hypertrophy for strength training was 1.23; for endurance training, it was 0.27; and for concurrent training, it was 0.85, with strength and concurrent training being significantly greater than endurance training only. The mean ES for strength development for strength training was 1.76; for endurance training, it was 0.78; and for concurrent training, it was 1.44. Strength and concurrent training was significantly greater than endurance training. The mean ES for power development for strength training only was 0.91; for endurance training, it was 0.11; and for concurrent training, it was 0.55. Significant differences were found between all the 3 groups. For moderator variables, resistance training concurrently with running, but not cycling, resulted in significant decrements in both hypertrophy and strength. Correlational analysis identified significant negative relationships between frequency (-0.26 to -0.35) and duration (-0.29 to -0.75) of endurance training for hypertrophy, strength, and power. Significant relationships (p < 0.05) between ES for decreased body fat and % maximal heart rate (r = -0.60) were also found. Our results indicate that interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected.     

Numerical analysis of morphology of natural hybrids between Carex hostiana and the members of Carex flava agg. (Cyperaceae)

Uni‐variate and multi‐variate statistical methods, based on data taken from dried specimens, were used to determine the morphological variance of Carex hostiana 3 Carex flava agg. hybrids and to establish their parents among members of the C. flava complex. The following hybrids were found: C. demissa 3 hostiana [C. 3 fulva], C. hostiana 3 lepidocarpa [C. ×leutzii] and C. flava 3 hostiana [C. 3 xanthocarpa]. The least variable traits, namely beak length, utricle length, ratio of beak length to the overall utricle length, female spike width, and width of the lowest bract, proved to be the most useful in delimiting the hybrids. Carex flava 3 hostiana specimens usually have long utricles and beaks, wide male and female spikes, as well as wide bracts and leaf blades. Carex hostiana 3 lepidocarpa specimens are characterized by relatively short beaks (with low ratio of beak length to the overall utricle length) and narrow bracts. Common features of C. demissa 3 hostiana specimens, on the other hand, are male spikes with long peduncles, usually longly parted female spikes and a long beak compared to the overall utricle length.     

High-mannose glycopeptides from embryonal carcinoma cells

Endo-beta-N-acetylglucosaminidase H released four major oligosaccharides from high-mannose glycopeptides prepared from embryonal carcinoma cells. The oligosacchaides were indistinguishable from (Man)9GlcNAc, (Man)8GlcNAc, (Man)7GlcNAc, and (Man)6GlcNAc isolated from fibroblasts. This result suggests that the biosynthetic pathway of asparagine-linked oligosaccharides in early embryonic cells is controlled as in adult cells, at least to the initial stage of processing of the nascent oligosaccharide transferred from lipid-linked intermediate.     

Relations in biomedical ontologies

To enhance the treatment of relations in biomedical ontologies we advance a methodology for providing consistent and unambiguous formal definitions of the relational expressions used in such ontologies in a way designed to assist developers and users in avoiding errors in coding and annotation. The resulting Relation Ontology can promote interoperability of ontologies and support new types of automated reasoning about the spatial and temporal dimensions of biological and medical phenomena.