Mitochondrial carriers function as monomers

Mitochondrial carriers link biochemical pathways in the mitochondrial matrix and cytosol by transporting metabolites, inorganic ions, nucleotides and cofactors across the mitochondrial inner membrane. Uncoupling proteins that dissipate the proton electrochemical gradient also belong to this protein family. For almost 35 years the general consensus has been that mitochondrial carriers are dimeric in structure and function. This view was based on data from inhibitor binding studies, small-angle neutron scattering, electron microscopy, differential tagging/affinity chromatography, size-exclusion chromatography, analytical ultracentrifugation, native gel electrophoresis, cross-linking experiments, tandem-fusions, negative dominance studies and mutagenesis. However, the structural folds of the ADP/ATP carriers were found to be monomeric, lacking obvious dimerisation interfaces. Subsequently, the yeast ADP/ATP carrier was demonstrated to function as a monomer. Here, we revisit the data that have been published in support of a dimeric state of mitochondrial carriers. Our analysis shows that when critical factors are taken into account, the monomer is the only plausible functional form of mitochondrial carriers. We propose a transport model based on the monomer, in which access to a single substrate binding site is controlled by two flanking salt bridge networks, explaining uniport and strict exchange of substrates.     

Odor-modulated upwind flight of the sphinx moth,Manduca sexta L.

1. Male and female Manduca sexta flew upwind in response to the odor of female sex-pheromone gland extract or fresh tobacco leaf respectively, and generated very similar zigzagging tracks along the odor plume. 2. After loss of odor during flight, males and females alike: (1) first flew slower and steered their flight more across the wind, then (2) stopped moving upwind, and finally (3) regressed downwind. 3. Males flying upwind in a pheromone plume in wind of different velocities maintained their ground speed near a relatively constant 'preferred' value by increasing their air speed as the velocity of the wind increased, and also maintained the average angle of their resultant flight tracks with respect to the wind at a preferred value by steering a course more precisely due upwind. 4. The inter-turn duration and turn rate, two measures of the temporal aspects of the flight track, were maintained, on average, with remarkable consistency across all wind velocities and in both sexes. The inter-turn durations also decreased significantly as moths approached the odor source, suggesting modulation of the temporal pattern of turning by some feature of the odor plume. This temporal regularity of turning appears to be one of the most stereotyped features of odor-modulated flight in M. sexta.     

Recombinant TLR5 Agonist CBLB502 Promotes NK Cell-Mediated Anti-CMV Immunity in Mice

Prior work using allogeneic bone marrow transplantation (allo-BMT) models showed that peritransplant administration of flagellin, a toll-like receptor 5 (TLR5) agonist protected murine allo-BMT recipients from CMV infection while limiting graft-vs-host disease (GvHD). However, the mechanism by which flagellin-TLR5 interaction promotes anti-CMV immunity was not defined. Here, we investigated the anti-CMV immunity of NK cells in C57BL/6 (B6) mice treated with a highly purified cGMP grade recombinant flagellin variant CBLB502 (rflagellin) followed by murine CMV (mCMV) infection. A single dose of rflagellin administered to mice between 48 to 72 hours prior to MCMV infection resulted in optimal protection from mCMV lethality. Anti-mCMV immunity in rflagellin-treated mice correlated with a significantly reduced liver viral load and increased numbers of Ly49H+ and Ly49D+ activated cytotoxic NK cells. Additionally, the increased anti-mCMV immunity of NK cells was directly correlated with increased numbers of IFN-γ, granzyme B- and CD107a producing NK cells following mCMV infection. rFlagellin-induced anti-mCMV immunity was TLR5-dependent as rflagellin-treated TLR5 KO mice had ∼10-fold increased liver viral load compared with rflagellin-treated WT B6 mice. However, the increased anti-mCMV immunity of NK cells in rflagellin-treated mice is regulated indirectly as mouse NK cells do not express TLR5. Collectively, these data suggest that rflagellin treatment indirectly leads to activation of NK cells, which may be an important adjunct benefit of administering rflagellin in allo-BMT recipients.     

Comparative studies on metabolic activity of planktonic,benthic and epiphytic bacteria

Summary Differences have been noted in metabolic activity of bacteria isolated from water, mud and from Canadian pondweed (Elodea canadensis).The epiphytic bacteria showed the greatest metabolic activity in every instance, benthic bacteria were least active and the water isolates were intermediate.Non-chromogenic bacteria were metabolically more active than the chromogens.Casamino acids proved to be the most readily oxidized substrate among the compounds studied. Glucose, succinate, fumarate and gluconate were readily used by most epiphytic and planktonic bacteria. Acetate was intermediate and fructose was the least suitable substrate for these organisms. Casamino acids proved to be the best substrate for all three groups, although the benthic bacteria were less active with this substrate than the former two groups of bacteria. Gluconate, succinate, pyruvate and acetate were intermediate, and glucose and fructose were least suitable for most of the benthic bacteria.     

Measuring antibody affinity and performing immunoassay at the single molecule level

Fluorescence correlation spectroscopy (FCS) enables direct observation of the translational diffusion of single fluorescent molecules in solution. When fluorescent hapten binds to antibody, analysis of FCS data yields the fractional amounts of free and bound hapten, allowing determination of the equilibrium binding constant. Equilibrium dissociation constants of anti-digoxin antibodies and corresponding fluorescein-labeled digoxigenin obtained by FCS and fluorescence polarization measurements are identical. It is also possible to follow a competitive displacement of the tracer from the antibody by unlabeled hapten using FCS in an immunoassay format. The fluorescence polarization immunoassay for vancomycin detection was used to test the FCS approach. Fitting of the FCS data for the molar fractions of free and bound fluorescein-labeled vancomycin yielded a calibration curve which could serve for determination of the vancomycin concentration in biological samples.     

The farnesoid X receptor -1G>T polymorphism influences the lipid response to rosuvastatin

The bile acid-activated nuclear receptor farnesoid X receptor (FXR) plays an important role in lipid and glucose metabolism, and in addition, it regulates multiple drug transporters involved in statin disposition. We examined whether a functional single nucleotide polymorphism (SNP) in FXR (-1G>T) influenced the lipid-lowering effect of rosuvastatin. In 385 Chinese patients with hyperlipidemia who had been treated with rosuvastatin 10 mg daily for at least 4 weeks, the association between the FXR -1G>T SNP and lipid response to rosuvastatin was analyzed. The FXR -1G>T SNP was not associated with baseline lipids but was significantly associated with the LDL cholesterol (LDL-C) and total cholesterol response to rosuvastatin. Carriers of the T-variant allele (GT+TT = 68+3) had 4.4% (95% CI: 1.2, 7.5%, P = 0.006) and 2.6% (95% CI: 0.3, 5.0%; P < 0.05) greater reductions in LDL-C and total cholesterol, respectively, compared with those with homozygous wild-type alleles. The association between the FXR polymorphism and the LDL-C response to rosuvastatin remained significant after adjusting for other covariants. This association of the variant allele of the FXR -1G>T polymorphism with a greater LDL-C response to rosuvastatin may suggest that this polymorphism influences the expression of the hepatic efflux transporters involved in biliary excretion of rosuvastatin.     

Sleep-related obstructive disordered breathing in cleft palate patients after palatoplasty

Sleep-disordered breathing is frequently associated with children presenting congenital midface defects. Because of structural and functional anomalies in the upper airway, children with cleft palate, especially after surgery, may carry a higher risk of developing sleep-disordered breathing. However, the presence of such sleep-disordered breathing in older cleft palate children has not been emphasized. The aim of this comparative overnight cardiorespiratory sleep study was to evaluate cleft palate patients according to sleep-disordered breathing. A group of 43 cleft palate children (17 girls and 26 boys; mean age, 12.1 +/- 3.8 years) was compared with a control group of 20 randomly selected, noncleft children matched for age, sex, and body mass index. None of the patients suffered from manifest sleep-disordered breathing. Cleft palate patients had a statistically significantly higher respiratory disturbance index and snoring index, but no increased apnea index. The data suggest that cleft palate patients having undergone primary closure of the palate demonstrate microsymptoms of nocturnal upper airway obstruction.     

Investigation of the human tympanic membrane oscillation ex vivo by Doppler optical coherence tomography

Investigations of the tympanic membrane (TM) can have an important impact on understanding the sound conduction in the ear and can therefore support the diagnosis and treatment of diseases in the middle ear. High‐speed Doppler optical coherence tomography (OCT) has the potential to describe the oscillatory behaviour of the TM surface in a phase‐sensitive manner and additionally allows acquiring a three‐dimensional image of the underlying structure. With repeated sound stimuli from 0.4 kHz to 6.4 kHz, the whole TM can be set in vibration and the spatially resolved frequency response functions (FRFs) of the tympanic membrane can be recorded. Typical points, such as the umbo or the manubrium of malleus, can be studied separately as well as the TM surface with all stationary and wave‐like vibrations. Thus, the OCT methodology can be a promising technique to distinguish between normal and pathological TMs and support the differentiation between ossicular and membrane diseases. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Replication of nucleolus-associated DNA during "G2 phase" in Physarum polycephalum

In the myxomycete, Physarum polycephalum, the bulk of nuclear DNA replication occurs during a period of a few hours immediately following upon mitosis. During the remainder of the intermitotic period, incorporation of thymidine-³H continues at a low rate in the region of the nucleolus (radioautographs). A few nuclei incorporated thymidine-³H into the extranucleolar chromatin at a high rate at all times of the intermitotic period. These nuclei were exceptionally large and they frequently contained several small nucleoli of different sizes rather than the one, central nucleolus which is characteristic of a normal interphase nucleus.