Monitoring transient elastic energy storage within the rotary motors of single FoF1-ATP synthase by DCO-ALEX FRET

The enzyme FoF1-ATP synthase provides the 'chemical energy currency' adenosine triphosphate (ATP) for living cells. Catalysis is driven by mechanochemical coupling of subunit rotation within the enzyme with conformational changes in the three ATP binding sites. Proton translocation through the membrane-bound Fo part of ATP synthase powers a 10-step rotary motion of the ring of c subunits. This rotation is transmitted to the gamma and epsilon subunits of the F1 part. Because gamma and epsilon subunits rotate in 120 deg steps, we aim to unravel this symmetry mismatch by real time monitoring subunit rotation using single-molecule Forster resonance energy transfer (FRET). One fluorophore is attached specifically to the F1 motor, another one to the Fo motor of the liposome-reconstituted enzyme. Photophysical artifacts due to spectral fluctuations of the single fluorophores are minimized by a previously developed duty cycle-optimized alternating laser excitation scheme (DCO-ALEX). We report the detection of reversible elastic deformations between the rotor parts of Fo and F1 and estimate the maximum angular displacement during the load-free rotation using Monte Carlo simulationsComment: 14 pages, 7 figure

36 degree step size of proton-driven c-ring rotation in FoF1-ATP synthase

Synthesis of the biological "energy currency molecule" adenosine triphosphate ATP is accomplished by FoF1-ATP synthase. In the plasma membrane of Escherichia coli, proton-driven rotation of a ring of 10 c subunits in the Fo motor powers catalysis in the F1 motor. While F1 uses 120 degree stepping, Fo models predict a step-by-step rotation of c subunits 36 degree at a time, which is here demonstrated by single-molecule fluorescence resonance energy transfer.Comment: 8 pages, 1 figur

Attributes of Dispersing Meadow Voles in Open-Grid Populations

Dispersal was investigated in two open-grid populations of meadow voles, Microtus pennsylvanicus (Ord, 1815) an central Virginia (U.S.A.) from November 1974 to April 1978. Dispersal was defined as immigration onto open, occupied population grids. Dispersers were distinguished from residents by weight at first capture. Individuals first captured at weights \u3c30 g were classified as residents; those first captured at \u3e30 g were classified as dispersers. Three independent lines of evidence support the validity of the 30-g criterion for recognizing dispersers in these vole populations. With frequent trapping and high trappability, particularly of young animals, this open-grid method of study offers two advantages in the study of dispersal. First, dispersers identified in this way exist an a biologically realistic environment as they move into or through an established population. Second, time-dependent components of the fitness of these dispersers can be monitored and compared with those of residents occupying the same habitat. Dispersers (immigrants) usually constituted \u3e75% of the minimum number of animals known to be alive in any week. Dispersal occurred continuously and was more important in situ reproduction as a source of new individuals in the population. Using the criterion of a negative correlation between the proportion of the population dispersing (immigrating) and grid population density, dispersal was not positively density-dependent. Although sex ratios of residents did not differ from 1:1, those of dispersers\u27 favored males on both grids. Nevertheless, 42% of all dispersers were female. Dispersers differed from adult (\u3e30 g) residents in that they were (1) significantly heavier than adult residents of the same sex and (2) more often in reproductive condition, both at first capture and later. Thus, dispersers had the potential to contribute more offspring per individual than residents. Dispersers and adult residents had comparable lifespans on both grids. Females had longer lifespans than males. Based these components of fitness, dispersers appeared to be comparable or superior residents. The attributes of the dispersers and the apparent lack of density dependence may be interpreted as evidence of pre-saturation dispersal in these populations

Detecting substeps in the rotary motors of FoF1-ATP synthase by Hidden Markov Models

FoF1-ATP synthase is the enzyme that provides the 'chemical energy currency' adenosine triphosphate, ATP, for living cells. The formation of ATP is accomplished by a stepwise internal rotation of subunits within the enzyme. We monitor subunit rotation by a single-molecule fluorescence resonance energy transfer (FRET) approach using two fluorophores specifically attached to the enzyme. To identify the stepsize of rotary movements by the motors of ATP synthase we simulated the confocal single-molecule FRET data of freely diffusing enzymes and developed a step finder algorithm based on 'Hidden Markov Models' (HMM). The HMM is able to find the proximity factors, P, for a three-level system and for a five-level system, and to unravel the dwell times of the simulated rotary movements. To identify the number of hidden states in the system, a likelihood parameter is calculated for the series of one-state to eight-state HMMs applied to each set of simulated data. Thereby, the basic prerequisites for the experimental single-molecule FRET data are defined that allow for discrimination between a 120 degree stepping mode or a 36 degree substep rotation mode for the proton-driven Fo motor of ATP synthase.Comment: 12 pages, 5 figure

Training tomorrow\u27s specialists in wildlife damage management

In 1990, Utah State University (USU) established a U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Animal Damage Control (ADC)-funded center dedicated to research, education, and extension in wildlife damage management. USU\u27 s Program in Wildlife Damage Management is designed to increase appreciation for wildlife damage management among wildlife professionals, provide superior training for future practitioners of wildlife damage management through education and innovative research, and create better public understanding of the role of wildlife damage management in today\u27s society

A Landowner’s Guide to Common North American Predators of Upland-nesting Birds

Predation has been identified as a key factor limiting upland-nesting bird reproductive success in many studies. These results suggest that the effects of predation could be reduced by establishing and maintaining suitable nesting habitats. In several studies, habitat management alone was able to maintain populations of upland-nesting birds at or slightly above threshold believed necessary to sustain populations. However, additional studies also have shown that avian populations increased substantially after predator populations were reduced or nesting birds were protected by restricting predator access through the use of electric fencing or creating nesting islands. These practices, however, need to be implemented in combination with good habitat management if optimum benefits are to be realized