Pasteurella multocida detection by 5' Taq nuclease assay: a new tool for use in diagnosing fowl cholera

A 5' Taq nuclease assay utilising minor groove binder technology and targeting the 16S rRNA gene was designed to detect Pasteurella multocida (the causative agent of fowl cholera) in swabs collected from poultry. The assay was first evaluated using pure cultures. The assay correctly identified four P. multocida taxonomic type strains, 18 P. multocida serovar reference strains and 40 Australian field isolates (17 from poultry, 11 from pigs and 12 from cattle). Representatives of nine other Pasteurella species, 26 other bacterial species (18 being members of the family Pasteurellaceae) and four poultry virus isolates did not react in the assay. The assay detected a minimum of approximately 10 cfu of P. multocida per reaction. Of 79 poultry swabs submitted to the laboratory for routine bacteriological culture, 17 were positive in the 5' Taq nuclease assay, but only 10 were positive by culture. The other 62 swabs were negative for P. multocida by both 5' Taq nuclease assay and culture. The assay is suitable for use in diagnosing fowl cholera, is more rapid than bacteriological culture, and may also have application in diagnosing P. multocida infections in cattle and pigs.     

Inference in ecology and evolution

Most ecologists and evolutionary biologists continue to rely heavily on null hypothesis significance testing, rather than on recently advocated alternatives, for inference. Here, we briefly review null hypothesis significance testing and its major alternatives. We identify major objectives of statistical analysis and suggest which analytical approaches are appropriate for each. Any well designed study can improve our understanding of biological systems, regardless of the inferential approach used. Nevertheless, an awareness of available techniques and their pitfalls could guide better approaches to data collection and broaden the range of questions that can be addressed. Although we should reduce our reliance on significance testing, it retains an important role in statistical education and is likely to remain fundamental to the falsification of scientific hypotheses.     

A threshold exists for the stimulatory effect of insulin on plasma L-carnitine clearance in humans

Maintaining hyperinsulinemia ( approximately 160 mU/l) during steady-state hypercarnitinemia ( approximately 550 mumol/l) increases skeletal muscle total carnitine (TC) content by approximately 15% within 5 h. The aim of the present study was to further examine the relationship between serum insulin concentration and skeletal muscle carnitine accumulation by attempting to identify the serum insulin concentration at which this stimulatory effect of insulin on carnitine retention becomes apparent. On four randomized experimental visits, eight healthy men (body mass index 23.8 +/- 0.9 kg/m(2)) underwent a 6-h euglycemic insulin clamp of 5, 30, 55, or 105 mU x m(-2) x min(-1) accompanied by a 5-h iv infusion of l-carnitine (15 mg/kg bolus followed by 10 mg x kg(-1) x h(-1)). The clamps produced steady-state serum insulin concentrations of 10.1 +/- 0.5, 48.8 +/- 1.0, 88.9 +/- 2.8, and 173.9 +/- 6.5 mU/l, respectively. During l-carnitine infusion, plasma TC concentration remained above 450 mumol/l during all four visits. However, there was a significant treatment effect of insulin (P < 0.001), such that by the end of infusion the plasma TC concentration in the 55- and 105-mU clamps was lower than that seen in the 5- (P < 0.05 and P < 0.01, respectively) and 30-mU (P < 0.01) clamps. The findings demonstrate that only high circulating serum insulin concentrations (> or =90 mU/l) are capable of stimulating skeletal muscle carnitine accumulation. This is of relevance to athletes, and the treatment of obesity and type 2 diabetes, where increasing skeletal muscle carnitine content may be used as tool to modify skeletal muscle energy metabolism.     

Aerobic fitness and performance in elite female futsal players

Despite its growing popularity, few studies have investigated specific physiological demands for elite female futsal. The aim of this study was to determine aerobic fitness in elite female futsal players using laboratory and field testing. Fourteen female futsal players from the Venezuelan National team (age =21.2±4.0 years; body mass =58.6±5.6 kg; height =161±5.0 cm) performed a progressive maximal treadmill test under laboratory conditions. Players also performed a progressive intermittent futsal-specific field test for endurance, the Futsal Intermittent Endurance Test (FIET), until volitional fatigue. Outcome variables were exercise heart rate (HR), VO₂, post-exercise blood lactate concentrations ([La]b) and running speeds (km · h^-1). During the treadmill test, VO₂max, maximal aerobic speed (MAS), HR and peak [La]b were 45.3±5.6 ml · kg^-1 · min^-1, 12.5±1.77 km · h^-1, 197±8 beats · min^-1 and 11.3±1.4 mmol · l^-1, respectively. The FIET total distance, peak running velocity, peak HR and [La]b were 1125.0±121.0 m, 15.2±0.5 km · h^-1, 199±8 beats · min^-1 and 12.5±2.2 mmol · l^-1, respectively. The FIET distance and peak speed were strongly associated (r= 0.85-87, p < 0.0001) with VO₂max and MAS, respectively. Peak HR and [La]b were not significantly different between tests. Elite female futsal players possess moderate aerobic fitness. Furthermore, the FIET can be considered as a valid field test to determine aerobic fitness in elite level female futsal players.     

Insights into the molecular basis of a bispecific antibody's target selectivity

Bispecific antibodies constitute a valuable class of therapeutics owing to their ability to bind 2 distinct targets. Dual targeting is thought to enhance biological efficacy, limit escape mechanisms, and increase target selectivity via a strong avidity effect mediated by concurrent binding to both antigens on the surface of the same cell. However, factors that regulate the extent of target selectivity are not well understood. We show that dual targeting alone is not sufficient to promote efficient target selectivity, and report the substantial roles played by the affinity of the individual arms, overall avidity and valence. More particularly, various monovalent bispecific IgGs composed of an anti-CD70 moiety paired with variants of the anti-CD4 mAb ibalizumab were tested for preferential binding and selective depletion of CD4⁺/CD70⁺ T cells over cells expressing only one of the target antigens that resulted from antibody dependent cell-mediated cytotoxicity. Variants exhibiting reduced CD4 affinity showed a greater degree of target selectivity, while the overall efficacy of the bispecific molecule was not affected.     

Talin influences the dynamics of the myosin VII-membrane interaction

Myosin VII (M7) and talin are ancient and ubiquitous actin-binding proteins with conserved roles in adhesion. Talin serves to link membrane receptors to the underlying actin cytoskeleton and forms a complex with M7 in Dictyostelium. The levels of talinA are tightly linked to M7 levels in Dictyostelium. Cells lacking M7 exhibit an 80% decrease in steady-state levels of talinA, whereas increased levels of M7 result in concomitant increases in total talinA. In contrast, changes in talinA levels do not affect M7 levels. Immunoprecipitation reveals that talinA and M7 are associated with each other in membrane fractions. Fluorescence recovery after photobleaching experiments on green fluorescent protein (GFP)-M7 cells expressing different levels of the M7 and talinA show that changes in the overall amounts of these two proteins influences the dynamics of membrane-associated M7. The recovery of GFP-M7 on the membrane is faster in cells lacking talinA and limited in the presence of excess amounts of talinA and M7. These results establish that M7 stabilizes talinA in the cytosol and, in return, talinA regulates the residence time of M7 at the plasma membrane, suggesting that these two proteins are both part of the same dynamic adhesion complex on the plasma membrane.