Evolution: vertebrate reproductive strategies get mixed up.

The mangrove killifish is the only vertebrate known to have a mixed-mating strategy, where hermaphrodites reproduce by either self-fertilisation or cross-breeding. New molecular evidence from this species reveals that occasional cross-breeding between common hermaphroditic individuals and rare pure males results in an injection of genetic variation into otherwise highly homozygous 'clonal' lineages.

Reduced heterozygosity depresses sperm quality in wild rabbits, Oryctolagus cuniculus.

When close relatives are forced to reproduce, the resulting offspring inherit above average homozygosity and reduced fitness. Biologists now recognize inbreeding depression in the wild, a phenomenon that will probably increase as natural populations become depleted and fragmented. Inbreeding depression is most commonly expressed as compromised fertility and embryogenesis, but actual mechanisms remain poorly understood, especially for wild populations.

Evolution: sex and cannibalism in redback spiders.

Female redback spiders cannibalise mating males. New research has shown they have evolved two separate sperm storage organs, allowing them to make post-copulatory paternity choices. Counter-adaptation by males, to maximise paternity after cannibalism, has led to the evolution of an abdominal constricting mechanism, which enhances short-term survival and mating success after attack by the female and maximises the chances of inseminating both sperm storage sites.

Three amino acids that are critical to formation and stability of the P22 tailspike trimer.

The P22 tailspike protein folds by forming a folding competent monomer species that forms a dimeric, then a non-native trimeric (protrimer) species by addition of folding competent monomers. We have found three residues, R549, R563, and D572, which play a critical role in both the stability of the native tailspike protein and assembly and maturation of the protrimer. King and colleagues reported previously that substitution of R563 to glutamine inhibited protrimer formation.

Reproductive biology: direct delivery of costly sex peptides.

Research on seminal fluid proteins is providing fundamental insights into the interactive evolution of male and female reproductive strategies. Two new studies demonstrate, first, how an influential male sex peptide in Drosophila is delivered to the female bound directly onto sperm cells, and second, that its subsequent release has significant reproductive costs for females.

Evolution: sexual arms races.

The reproductive interests of males and females usually differ, resulting in sexual conflict. Recent studies in which experimental selection trials were carried out under conditions of either 'high' or 'low' sexual conflict show that conflict can promote speciation and reduce female reproductive success.

Pressure dissociation studies provide insight into oligomerization competence of temperature-sensitive folding mutants of P22 tailspike.

Several temperature-sensitive folding (tsf) mutants of the tailspike protein from bacteriophage P22 have been found to fold with lower efficiency than the wild-type sequence, even at lowered temperatures. Previous refolding studies initiated from the unfolded monomer have indicated that the tsf mutations decrease the rate of structured monomer formation. We demonstrate that pressure treatment of the tailspike aggregates provides a useful tool to explore the effects of tsf mutants on the assembly pathway of the P22 tailspike trimer.

Maximizing recovery of native protein from aggregates by optimizing pressure treatment.

Recovering native protein from aggregates is a common obstacle in the production of recombinant proteins. Recent reports have shown that hydrostatic pressure is an attractive alternative to traditional denature-and-dilute techniques, both in terms of yield and process simplicity. To determine the effect of process variables, we subjected tailspike aggregates to a variety of pressure-treatment conditions.

Spermatozoal traits and sperm competition in Atlantic salmon: relative sperm velocity is the primary determinant of fertilization success.

Sperm competition occurs when sperm from more than one male compete for fertilizations. This form of post-copulatory sexual selection is recognized as a significant and widespread force in the evolution of male reproductive biology and as a key determinant of differential male reproductive success. Despite its importance, however, detailed mechanisms of sperm competition at the gamete level remain poorly understood.

C-terminal hydrophobic interactions play a critical role in oligomeric assembly of the P22 tailspike trimer.

The tailspike protein from the bacteriophage P22 is a well characterized model system for folding and assembly of multimeric proteins. Folding intermediates from both the in vivo and in vitro pathways have been identified, and both the initial folding steps and the protrimer-to-trimer transition have been well studied. In contrast, there has been little experimental evidence to describe the assembly of the protrimer.

Relative testis size and sperm morphometry across mammals: no evidence for an association between sperm competition and sperm length.

Understanding why there is extensive variation in sperm form and function across taxa has been a challenge because sperm are specialized cells operating at a microscopic level in a complex environment. This comparative study collates published data to determine whether the evolution of sperm morphometry (sperm total length and separate component dimensions) is associated with sperm competition (when different males' sperm mix and compete for a female's ova) across 83 mammalian species. We use relative testes mass as an indicator of the intensity of sperm competition across taxa: relative investment into testes is widely accepted to predict the level of sperm competition that a species or population endures.

Experimental evidence for the evolution of numerous, tiny sperm via sperm competition.

Sperm competition, when sperm from different males compete to fertilize a female's ova, is a widespread and fundamental force in the evolution of animal reproduction. The earliest prediction of sperm competition theory was that sperm competition selected for the evolution of numerous, tiny sperm, and that this force maintained anisogamy. Here, we empirically test this prediction directly by using selective breeding to generate controlled and independent variance in sperm size and number traits in the cricket Gryllus bimaculatus.

Sexual selection and speciation in mammals, butterflies and spiders.

Recently refined evolutionary theories propose that sexual selection and reproductive conflict could be drivers of speciation. Male and female reproductive optima invariably differ because the potential reproductive rate of males almost always exceeds that of females: females are selected to maximize mate 'quality', while males can increase fitness through mate 'quantity'. A dynamic, sexually selected conflict therefore exists in which 'competitive' males are selected to override the preference tactics evolved by 'choosy' females.

The virally encoded fungal toxin KP4 specifically blocks L-type voltage-gated calcium channels.

KP4 is a virally encoded fungal toxin secreted by the P4 killer strain of Ustilago maydis. Previous studies demonstrated that this toxin inhibits growth of the target fungal cells by blocking calcium uptake rather than forming channels, as had been suggested previously. Unexpectedly, this toxin was also shown to inhibit voltage-gated calcium channel activity in mammalian cells.

Expanding the boundaries of occupational therapy practice through student fieldwork experiences: description of a provincially-funded community development project.

The numbers of occupational therapists in community practice are not yet large enough to provide fieldwork placements to accommodate all students. This article describes a project designed to educate community agencies that do not employ occupational therapists, about our service while at the same time securing new fieldwork placements. We used on-site different discipline and offsite same discipline supervision to provide students to selected agencies without cost.

Artificial selection and heritability of sperm length in Gryllus bimaculatus.

The adaptive significance of variation in sperm size remains poorly understood but there has been even less attention focused on the genetic mechanisms controlling spermatozoal traits (only three species have been studied). Here we explore heritability and artificial selection of sperm length in the cricket Gryllus bimaculatus. Using a within-family selection design we selected sperm with increasing and decreasing sperm size and bred divergence across five generations.

Sperm competition experiments between lines of crickets producing different sperm lengths.

Sperm numbers can be important determinants of fertilization success in sperm competition. However, the importance of variation in sperm size is less well understood. Sperm size varies significantly both between and within species and comparative studies have suggested that some of this variance can be explained by sperm competition.

KP4 fungal toxin inhibits growth in Ustilago maydis by blocking calcium uptake.

KP4 is a virally encoded fungal toxin secreted by the P4 killer strain of Ustilago maydis. From our previous structural studies, it seemed unlikely that KP4 acts by forming channels in the target cell membrane. Instead, KP4 was proposed to act by blocking fungal calcium channels, as KP4 was shown to inhibit voltage-gated calcium channels in rat neuronal cells, and its effects on fungal cells were abrogated by exogenously added calcium.

Reduced sperm counts in guppies (Poecilia reticulata) following exposure to low levels of tributyltin and bisphenol A.

There is increasing evidence that normal male reproductive function can be disrupted by exposure to pollutants in the environment that can exogenously mimic, antagonize or block sex-hormone function. One possible consequence of exposure to these xenobiotics is disruption to spermatogenesis, but results thus far provide only indirect and inconsistent evidence. In this study we exposed adult male guppies (Poeciliidae: Teleostei) to environmentally relevant levels of the common xenobiotics tributyltin (11.

The evolution of sperm length in moths.

Sperm form and function remain poorly understood despite being of fundamental biological importance. An instructive approach has been to examine evolutionary associations across comparable taxa between sperm characters and other, potentially selective reproductive traits. We adopt this approach here in a comparative study examining how sperm lengths are associated with male and female reproductive characters across moths.

Interdisciplinary pilot project in a rehabilitation setting.

This project qualitatively evaluated the planning, implementation, and outcome of an interdisciplinary model of clinical education. Expectations of physiotherapy (PT), occupational therapy (OT), and speech-language pathology (SLP) students and clinicians were assessed to determine whether the model allowed for the acquisition of the interdisciplinary knowledge and skills needed for current practice. Students from OT (n = 5), PT (n = 3), and SLP (n = 1) undertook normally scheduled five-to-eight-week clinical placements, beginning on the same start date.

From independence to interdependence. Creating synergistic healthcare teams.

As the structure of healthcare institutions changes, nurse administrators frequently are being called on to lead interdisciplinary programs. To be successful in this new health paradigm, teams must strive to create total stakeholder satisfaction by adopting a mindset that work is interdependent, not independent, and then striving to work synergistically. The author presents 12 themes that emerged from a study investigating the essential elements of synergistic team relationships.

Mammalian sperm morphometry.

Understanding the adaptive significance of sperm form and function has been a challenge to biologists because sperm are highly specialized cells operating at a microscopic level in a complex environment. A fruitful course of investigation has been to use the comparative approach. This comparative study attempts to address some fundamental questions of the evolution of mammalian sperm morphometry.