Control of male sexual behavior in Drosophila by the sex determination pathway

Understanding how genes influence behavior, including sexuality, is one of biology's greatest challenges. Much of the recent progress in understanding how single genes can influence behavior has come from the study of innate behaviors in the fruit fly Drosophila melanogaster. In particular, the elaborate courtship ritual performed by the male fly has provided remarkable insights into how the neural circuitry underlying sexual behavior--which is largely innate in flies--is built into the nervous system during development, and how this circuitry functions in the adult. In this review we will discuss how genes of the sex determination pathway in Drosophila orchestrate the developmental events necessary for sex-specific behaviors and physiology, and the broader lessons this can teach us about the mechanisms underlying the development of sex-specific neural circuitry.     

Cryptic sexual conflict in gift-giving insects: chasing the chase-away

The chase-away model of sexual selection posits that elaborate male sexual displays arise because they exploit preexisting biases in females' sensory systems and induce females to mate in a suboptimal manner. An essential element of this hypothesis is that such manipulation should quickly lead to female resistance to male displays. Nuptial food gifts may be a frequent conduit by which males attempt to influence the mating behavior of females against females' own reproductive interests. In decorated crickets Gryllodes sigillatus, such inducements come in the form of a spermatophylax, a gelatinous mass forming part of the male's spermatophore and consumed by the female after mating. We conducted experiments in which spermatophylaxes obtained from male G. sigillatus were offered as novel food gifts to females of a non-gift-giving species (Acheta domesticus) having no evolutionary history of spermatophylax consumption. Female A. domesticus that were allowed to consume the spermatophylax took significantly longer to remate than when given no such opportunity. In contrast, when female G. sigillatus were prevented from consuming their partners' nuptial gifts, there was no difference in their propensity to remate relative to females permitted to consume a food gift after mating. These results suggest that the spermatophylax synthesized by male G. sigillatus contains substances designed to inhibit the sexual receptivity of their mates but that female G. sigillatus have evolved reduced responsiveness to these substances.     

Pathogenomic sequence analysis of Bacillus cereus and Bacillus thuringiensis isolates closely related to Bacillus anthracis

Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis are closely related gram-positive, spore-forming bacteria of the B. cereus sensu lato group. While independently derived strains of B. anthracis reveal conspicuous sequence homogeneity, environmental isolates of B. cereus and B. thuringiensis exhibit extensive genetic diversity. Here we report the sequencing and comparative analysis of the genomes of two members of the B. cereus group, B. thuringiensis 97-27 subsp. konkukian serotype H34, isolated from a necrotic human wound, and B. cereus E33L, which was isolated from a swab of a zebra carcass in Namibia. These two strains, when analyzed by amplified fragment length polymorphism within a collection of over 300 of B. cereus, B. thuringiensis, and B. anthracis isolates, appear closely related to B. anthracis. The B. cereus E33L isolate appears to be the nearest relative to B. anthracis identified thus far. Whole-genome sequencing of B. thuringiensis 97-27and B. cereus E33L was undertaken to identify shared and unique genes among these isolates in comparison to the genomes of pathogenic strains B. anthracis Ames and B. cereus G9241 and nonpathogenic strains B. cereus ATCC 10987 and B. cereus ATCC 14579. Comparison of these genomes revealed differences in terms of virulence, metabolic competence, structural components, and regulatory mechanisms.     

Stimulation of KatG catalase activity by peroxidatic electron donors

Catalase-peroxidases (KatGs) use a peroxidase scaffold to support robust catalase activity, an ability no other member of its superfamily possesses. Because catalase turnover requires H(2)O(2) oxidation, whereas peroxidase turnover requires oxidation of an exogenous electron donor, it has been anticipated that the latter should inhibit catalase activity. To the contrary, we report peroxidatic electron donors stimulated catalase activity up to 14-fold, particularly under conditions favorable to peroxidase activity (i.e., acidic pH and low H(2)O(2) concentrations). We observed a "low-" and "high-K(M)" component for catalase activity at pH 5.0. Electron donors increased the apparent k(cat) for the "low-K(M)" component. During stimulated catalase activity, less than 0.008 equivalents of oxidized donor accumulated for every H(2)O(2) consumed. Several classical peroxidatic electron donors were effective stimulators of catalase activity, but pyrogallol and ascorbate showed little effect. Stopped-flow evaluation showed that a Fe(III)-O(2)(-)-like intermediate dominated during donor-stimulated catalatic turnover, and this intermediate converted directly to the ferric state upon depletion of H(2)O(2). In this respect, the Fe(III)-O(2)(-) -like species was more prominent and persistent than in the absence of the donor. These results point toward a much more central role for peroxidase substrates in the unusual catalase mechanism of KatG.     

Using knowledge brokers to facilitate the uptake of pediatric measurement tools into clinical practice: a before-after intervention study

Background

There is a large quality of care gap for patients with osteoporosis. As a fragility fracture is a strong indicator of underlying osteoporosis, it offers an ideal opportunity to initiate investigation and treatment. However, studies of post-fracture populations document screening and treatment rates below 20% in most settings. This is despite the fact that bone mineral density (BMD) scans are effective at identifying patients at high risk of fracture, and effective drug treatments are widely available. Effective interventions are required to remedy this incongruity in current practice.

Methods

This study reviewed randomised controlled trials (RCT) involving fully qualified healthcare professionals caring for patients with a fragility fracture in all healthcare settings. Any intervention designed to modify the behaviour of healthcare professionals or implement a service delivery change was considered. The main outcomes were BMD scanning and osteoporosis treatment with anti-resorptive therapy. The electronic databases Medline and Embase were searched from 1994 to June 2010 to identify relevant articles in English. Post-intervention risk differences (RDs) were calculated for the main outcomes and any additional study primary outcomes; the trials were meta-analysed.

Results

A total of 2814 potentially relevant articles were sifted; 18 were assessed in full text. Nine RCTs evaluating ten interventions met the inclusion criteria for the review. All were from North America. Four studies focused on patients with a hip fracture, three on fractures of the wrist/distal forearm, and two included several fracture sites consistent with a fragility fracture. All studies reported positive effects of the intervention for the main study outcomes of BMD scanning and osteoporosis treatment. For BMD scanning the overall risk ratio (95% CI) was 2.8 (2.16 to 3.64); the RD was 36% (21% to 50%). For treatment with anti-resorptive therapy the overall risk ratio (95% CI) was 2.48 (1.92 to 3.2); the RD was 20% (10% to 30%).

Conclusions

All interventions produced positive effects on BMD scanning and osteoporosis treatment rates post-fracture. Despite sizeable increases, investigation and treatment rates remain sub-optimal. Long-term compliance with osteoporosis medications needs to be addressed, as the majority of studies reported treatment rates at six-month follow up only. Studies would be more informative if treatment criteria were defined a priori to facilitate understanding of whether patients were being treated appropriately and integrated economic analyses would be helpful for informing policy implementation decisions.     

Water-soluble PDE4 inhibitors for the treatment of dry eye

PDE4 inhibitors have the potential to alleviate the symptoms and underlying inflammation associated with dry eye. Disclosed herein is the development of a novel series of water-soluble PDE4 inhibitors. Our studies led to the discovery of coumarin 18, which is effective in a rabbit model of dry eye and a tear secretion test in rats.     

Sex-biased dispersal and natal philopatry in the diamondback terrapin, Malaclemys terrapin

Nesting ecology and population studies indicate that diamondback terrapins (Malaclemys terrapin) exhibit nest site fidelity and high habitat fidelity. However, genetic studies indicate high levels of gene flow. Because dispersal affects the genetics and population dynamics of a species, we used six highly polymorphic microsatellite markers to investigate sex-biased dispersal and natal philopatry of M. terrapin in Barnegat Bay, NJ. We compared results of spatial autocorrelation analysis, assignment methods and Wright's F(ST) estimators to a mark-recapture analysis. Mark-recapture analysis over a 4-year period indicated that most individuals have relatively small home ranges (<2 km), with mature females displaying greater home ranges than males. Goodness of fit analysis of our mark-recapture study indicated that some juvenile males were likely transient individuals moving through our study location. Mean assignment indices and first-generation migrant tests indicated that mature males were more prone to disperse than mature females, but first-generation migrant tests indicated that per capita there are more female than male dispersers. Thus, the relative importance of males and females on gene flow in terrapin populations may change in relation to population sex ratios. Spatial autocorrelation analysis indicated that mature females exhibited natal philopatry to nesting beaches, but first-generation migrant tests indicated that a small number of females failed to nest on natal beaches. Finally, we discuss the important conservation implications of male-biased dispersal and natal philopatry in the diamondback terrapin.