Patterns of population genetic variation in sympatric chiltoniid amphipods within a calcrete aquifer reveal a dynamic subterranean environment

Calcrete aquifers from the Yilgarn region of arid central Western Australia contain an assemblage of obligate groundwater invertebrate species that are each endemic to single aquifers. Fine-scale phylogeographic and population genetic analyses of three sympatric and independently derived species of amphipod (Chiltoniidae) were carried out to determine whether there were common patterns of population genetic structure or evidence for past geographic isolation of populations within a single calcrete aquifer. Genetic diversity in amphipod mitochondrial DNA (cytochrome c oxidase subunit I gene) and allozymes were examined across a 3.5 km² region of the Sturt Meadows calcrete, which contains a grid of 115 bore holes (=wells). Stygobiont amphipods were found to have high levels of mitochondrial haplotype diversity coupled with low nucleotide diversity. Mitochondrial phylogeographic structuring was found between haplogroups for one of the chiltoniid species, which also showed population structuring for nuclear markers. Signatures of population expansion in two of the three species, match previous findings for diving beetles at the same site, indicating that the system is dynamic. We propose isolation of populations in refugia within the calcrete, followed by expansion events, as the most likely source of intraspecific genetic diversity, due to changes in water level influencing gene flow across the calcrete.     

Identification of a putative regulatory subunit of a calcium-activated potassium channel in the dup(3q) syndrome region and a related sequence on 22q11.2

Duplication of a segment of the long arm of human chromosome 3 (3q26.3-q27) results in a syndrome characterized by multiple congenital abnormalities and neurological anomalies in some patients. We have identified a novel gene (KCNMB3) that maps to this region. KCNMB3 has significant sequence similarity to the regulatory subunit of the large-conductance calcium-activated potassium channel. Due to the significance of potassium channels in neuronal functions, the overexpression of this gene may play a role in the abnormal neurological functions seen in some of these patients. A related sequence corresponding to the second and third exons of this gene resides in the pericentromeric region of 22q11, where a number of other unprocessed pseudogenes are known to map.     

High-performance liquid chromatographic assay of lactic, pyruvic and acetic acids and lactic acid stereoisomers in calf feces, rumen fluid and urine

To facilitate clinical investigation of metabolic acidosis, a high-performance liquid chromatographic method was adapted and validated for the chiral separation of D-(-) and L-(+)-lactic acid in calf feces, rumen fluid and urine. A non-chiral method was also adapted and validated for the separation of pyruvic, acetic and DL-(+/-)-lactic acids in calf feces and DL-(+/-)-lactic and pyruvic acids in rumen fluid. Separation and quantification were achieved using a reversed phase sulphonated polystyrenedivinylbenzene analytical column for pyruvic, acetic and racemic lactic acids and by a 3 microm octadecylsilane (ODS) packed analytical column coated with N,N-dioctyl-L-alanine as the chiral selector for the separation of lactic acid enantiomers with Cu(II)-containing eluents by stereoselective ligand exchange chromatography. Endogenous analytes were present in validation samples over a range of concentrations (0.2-14.8 mmol/l). For the stereoselective assay, mean intra-day accuracy ranged from 90.6 to 108.4% and intra-day precision from 0.3 to 13.8%. For the non-stereoselective assay, mean intra-day accuracy ranged from 90.4 to 108.8% and intra-day precision from 1.5 to 11.1%. The limit of quantitation was 1.0 mmol/l for D- and L-lactic acid, 0.06125 mmol/l for pyruvic acid, 1.0 mmol/l for DL-lactic acid and 1 mmol/l for acetic acid. These assays can be used to study the role of the gastrointestinal tract and kidney in metabolic acidosis.     

Reducing a cost of traumatic insemination: female bedbugs evolve a unique organ

The frequent wounding of female bedbugs (Cimex lectularius: Cimicidae) during copulation has been shown to decrease their fitness, but how females have responded to this cost in evolutionary terms is unclear. The evolution of a unique anatomical structure found in female bedbugs, the spermalege, into which the male's intromittent organ passes during traumatic insemination, is a possible counteradaptation to harmful male traits. Several functions have been proposed for this organ, and we test two hypotheses related to its role in sexual conflict. We examine the hypotheses that the spermalege functions to (i) defend against pathogens introduced during traumatic insemination; and (ii) reduce the costs of wound healing during traumatic insemination. Our results support the 'defence against pathogens' hypothesis, suggesting that the evolution of this unique cimicid organ resulted, at least partly, from selection to reduce the costs of mating-associated infection. We found no evidence that the spermalege reduces the costs of wound healing.     

Coexistence of group I and group II chaperonins in the archaeon Methanosarcina mazei

Two distantly related classes of cylindrical chaperonin complexes assist in the folding of newly synthesized and stress-denatured proteins in an ATP-dependent manner. Group I chaperonins are thought to be restricted to the cytosol of bacteria and to mitochondria and chloroplasts, whereas the group II chaperonins are found in the archaeal and eukaryotic cytosol. Here we show that members of the archaeal genus Methanosarcina co-express both the complete group I (GroEL/GroES) and group II (thermosome/prefoldin) chaperonin systems in their cytosol. These mesophilic archaea have acquired between 20 and 35% of their genes by lateral gene transfer from bacteria. In Methanosarcina mazei G?1, both chaperonins are similarly abundant and are moderately induced under heat stress. The M. mazei GroEL/GroES proteins have the structural features of their bacterial counterparts. The thermosome contains three paralogous subunits, alpha, beta, and gamma, which assemble preferentially at a molar ratio of 2:1:1. As shown in vitro, the assembly reaction is dependent on ATP/Mg2+ or ADP/Mg2+ and the regulatory role of the beta subunit. The co-existence of both chaperonin systems in the same cellular compartment suggests the Methanosarcina species as useful model systems in studying the differential substrate specificity of the group I and II chaperonins and in elucidating how newly synthesized proteins are sorted from the ribosome to the proper chaperonin for folding.     

Beverage specific alcohol intake in a population-based study: Evidence for a positive association between pulmonary function and wine intake

Background  

Lung function is a strong predictor of cardiovascular and all-cause mortality. Previous studies suggest that alcohol exposure may be linked to impaired pulmonary function through oxidant-antioxidant mechanisms. Alcohol may be an important source of oxidants; however, wine contains several antioxidants. In this study we analyzed the relation of beverage specific alcohol intake with forced expiratory volume in one second (FEV₁) and forced vital capacity (FVC) in a random sample of 1555 residents of Western New York, USA.     

A discrete domain of the human TrkB receptor defines the binding sites for BDNF and NT-4

TrkB is a member of the Trk family of tyrosine kinase receptors. In vivo, the extracellular region of TrkB is known to bind, with high affinity, the neurotrophin protein brain-derived neurotrophic factor (BDNF) and neurotrophin-4 (NT-4). We describe the expression and purification of the second Ig-like domain of human TrkB (TrkBIg(2)) and show, using surface plasmon resonance, that this domain is sufficient to bind BDNF and NT-4 with subnanomolar affinity. BDNF and NT-4 may have therapeutic implications for a variety of neurodegenerative diseases. The specificity of binding of the neurotrophins to their receptor TrkB is therefore of interest. We examine the specificity of TrkBIg(2) for all the neurotrophins, and use our molecular model of the BDNF-TrkBIg(2) complex to examine the residues involved in binding. It is hoped that the understanding of specific interactions will allow design of small molecule neurotrophin mimetics.     

Interactions of the nuclear matrix-associated steroid receptor binding factor with its DNA binding element in the c-myc gene promoter

Steroid receptor binding factor (RBF) was originally isolated from avian oviduct nuclear matrix. When bound to avian genomic DNA, RBF generates saturable high-affinity binding sites for the avian progesterone receptor (PR). Recent studies have shown that RBF binds to a 54 bp element in the 5'-flanking region of the progesterone-regulated avian c-myc gene, and nuclear matrix-like attachment sites flank the RBF element [Lauber et al. (1997) J. Biol. Chem. 272, 24657-24665]. In this paper, electrophoretic mobility shift assays (EMSAs) and S1 nuclease treatment are used to demonstrate that the RBF-maltose binding protei (MBP) fusion protein binds to single-stranded DNA of its element. Only the N-terminal domain of RBF binds the RBF DNA element as demonstrated by southwestern blot analyses, and by competition EMSAs between RBF-MBP and the N-terminal domain. Mass spectrometric analysis of the C-terminal domain of RBF demonstrates its potential to form noncovalent protein-protein interactions via a potential leucine-isoleucine zipperlike structure, suggesting a homo- and/or possible heterodimer structure in solution. These data support that the nuclear matrix binding site (acceptor site) for PR in the c-myc gene promoter is composed of RBF dimers bound to a specific single-stranded DNA element. The dimers of RBF are generated by C-terminal leucine zipper and the DNA binding occurs at the N-terminal parallel beta-sheet DNA binding motif. This complex is flanked by nuclear matrix attachment sites.