Life Sciences Commons^™

Role Of The Epididymis In Sperm Competition, Russell Jones, Jl Dacheux, Brett Nixon, Heath Ecroyd

Heath Ecroyd

Although it is generally understood that the testes recruited kidney ducts for reproductive function during the evolution of vertebrates, little is understood of the biological significance of the adaptation. In the context of the evolution of the mammalian epididymis, this report provides evidence that a major role of the epididymis is to enhance a male's chance of achieving paternity in a competitive mating system. A unique example of sperm cooperation, in monotremes is used as evidence that the epididymis produces sperm competition proteins to form groups of 100 sperm into bundles that have a forward motility nearly thrice that of …

Tyrosine Phosphorylation Of Hsp-90 During Mammalian Sperm Capacitation, Heath Ecroyd, Russell Jones, Robert Aitken

Heath Ecroyd

The process of sperm capacitation is correlated with activation of a signal transduction pathway leading to protein tyrosine phosphorylation. Whereas phosphotyrosine expression is an essential prerequisite for fertilization, the proteins that are phosphorylated during capacitation have not yet been identified. In the present study, we observed that a major target of this signaling pathway is the molecular chaperone protein, heat shock protein (HSP)-86, a member of the HSP-90 family of HSPs. We used cross-immunoprecipitation experiments to confirm the tyrosine phosphorylation of HSP-86, a process that is not inhibited by the ansamycin antibiotic, geldanamycin. The general significance of these findings was …

Dissociation From The Oligomeric State Is The Rate-Limiting Step In Fibril Formation By Kappa-Casein, Heath Ecroyd, Tomas Koudelka, David Thorn, Danielle Williams, Glyn Devlin, Peter Hoffmann, John Carver

Heath Ecroyd

Amyloid fibrils are aggregated and precipitated forms of protein in which the protein exists in highly ordered, long, unbranching threadlike formations that are stable and resistant to degradation by proteases. Fibril formation is an ordered process that typically involves the unfolding of a protein to partially folded states that subsequently interact and aggregate through a nucleation-dependent mechanism. Here we report on studies investigating the molecular basis of the inherent propensity of the milk protein, kappa-casein, to form amyloid fibrils. Using reduced and carboxymethylated kappa-casein ( RCM kappa-CN), we show that fibril formation is accompanied by a characteristic increase in thioflavin …

The Effect Of Small Molecules In Modulating The Chaperone Activity Of Alpha B-Crystallin Against Ordered And Disordered Protein Aggregation, Heath Ecroyd, John Carver

Heath Ecroyd

Protein aggregation can proceed via disordered or ordered mechanisms, with the latter being associated with amyloid fibril formation, which has been linked to a number of debilitating conditions including Alzheimer's, Parkinson's and Creutzfeldt-Jakob diseases. Small heat-shock proteins (sHsps), such as alpha B-crystallin, act as chaperones to prevent protein aggregation and are thought to play a key role in the prevention of protein-misfolding diseases. In this study, we have explored the potential for small molecules such as arginine and guanidine to affect the chaperone activity of alpha B-crystallin against disordered (amorphous) and ordered (amyloid fibril) forms of protein aggregation. The effect …

Analysis Of The Mechanism By Which Calcium Negatively Regulates The Tyrosine Phosphorylation Cascade Associated With Sperm Capacitation, Mark Baker, Louise Hethrington, Heath Ecroyd, Shaun Roman, Robert Aitken

Heath Ecroyd

The capacitation of mammalian spermatozoa involves the activation of a cAMP-mediated signal transduction pathway that drives tyrosine phosphorylation via mechanisms that are unique to this cell type. Controversy surrounds the impact of extracellular calcium on this process, with positive and negative effects being recorded in independent publications. We clearly demonstrate that the presence of calcium in the external medium decreases tyrosine phosphorylation in both human and mouse spermatozoa. Under these conditions, a rise in intracellular pH was recorded, however, this event was not responsible for the observed changes in phosphotyrosine expression. Rather, the impact of calcium on tyrosine phosphorylation in …

The Two Faced Nature Of Milk Casein Proteins: Amyloid Fibril Formation And Chaperone-Like Activity, David Thorn, Heath Ecroyd, John Carver

Heath Ecroyd

Molecular chaperones are a diverse group of proteins that stabilise partially folded target proteins to prevent their misfolding, aggregation and potential precipitation under conditions of cellular stress, e.g. elevated temperature. Protein aggregation, particularly the formation of highly ordered protein aggregates termed amyloid fibrils, is of considerable research interest because of its intimate association with a wide range of debilitating diseases, including Alzheimer's, Parkinson's and Huntington's diseases and type II diabetes. In this review, we discuss the ability of the milk casein proteins to act in a chaperone-like manner. This property is of biological importance since at least two of the …

Post-Testicular Sperm Environment And Fertility, Jean-Luc Gatti, Sandrine Castella, Francoise Dacheux, Heath Ecroyd, S Metayer, Veronique Thimon, Jean-Louis Dacheux

Heath Ecroyd

When mammalian spermatozoa exit the testis, they show a highly specialized morphology; however, they are not yet able to carry out their task: to fertilize an oocyte. This property, that includes the acquisition of motility and the ability to recognize and to fuse with the oocyte investments, is gained only after a transit through the epididymis during which the spermatozoa from the testis travel to the vas deferens. The exact molecular mechanisms that turn these cells into fertile gametes still remain mysterious, but surface-modifying events occurring in response to the external media are key steps in this process. Our laboratory …

Testicular Descent, Sperm Maturation And Capacitation. Lessons From Our Most Distant Relatives, The Monotremes, Russell Jones, Heath Ecroyd, Jean-Louis Dacheux, Brett Nixon

Heath Ecroyd

The present review examines whether monotremes may help to resolve three questions relating to sperm production in mammals: why the testes descend into a scrotum in most mammals, why spermatozoa are infertile when they leave the testes and require a period of maturation in the specific milieu provided by the epididymides, and why ejaculated spermatozoa cannot immediately fertilise an ovum until they undergo capacitation within the female reproductive tract. Comparisons of monotremes with other mammals indicate that there is a need for considerable work on monotremes. It is hypothesised that testicular descent should be related to epididymal differentiation. Spermatozoa and …

North American Pollinator Partnership Conference: Making A Difference One Pollinator At A Time, Tammy Horn

Tammy Horn

The North American Pollinator Protection Campaign 10th Anniversary conference, held in Washington DC 2010, is the last place I saw myself being invited to a couple of years ago. Unemployed and changing careers, I withdrew from conventional academe to work bees on surface mine sites in Kentucky, which are not conventional places to define new careers.

Beeconomy: What Women And Bees Can Teach Us About Local Trade And The Global Market, Tammy Horn

Tammy Horn

Queen bee. Worker bees. Busy as a bee. These phrases have shaped perceptions of women for centuries, but how did these stereotypes begin? Who are the women who keep bees and what can we learn from them? Beeconomy examines the fascinating evolution of the relationship between women and bees around the world. From Africa to Australia to Asia, women have participated in the pragmatic aspects of honey hunting and in the more advanced skills associated with beekeeping as hive technology has advanced through the centuries.

Synthesizing the various aspects of hive-related products, such as beewax and cosmetics, as well as …

Modulation Of Methylphenidate Effects On Wheel Running And Acoustic Startle By Acute Food Deprivation In Commercially And Selectively Bred Rats., Clinton Chapman, Nancy Dess, Ian Mclaughlin

Clinton D Chapman

Behavioral effects of the same dose of the same drug can vary in degree and direction between and within individuals. The present study examines behavioral base rates, feeding status, and dispositional differences as sources of inter- and intra-individual heterogeneity in drug response. Modulation of the effects of methylphenidate (MPD) on wheel running and acoustic startle by food deprivation was examined in three experiments. Freely fed or food deprived Harlan Sprague–Dawley rats (running study) or rats selectively bred for low (LoS) and high (HiS) saccharin intake (running and startle studies) were given MPD (10 mg/kg) or saline before testing. Overall drug …

Who's To Blame When A Business Fails? How Journalistic Death Metaphors Influence Responsibility Attributions, Ann Williams

Ann E Williams

This study unites a textual analysis and an experimental audience study to document the use of death metaphor in business news and to assess the impact that death metaphor has on audiences' attributions of responsibility for corporate failure. The findings show that death metaphors are frequently used in financial press coverage and that the use of death metaphor influences audience members' responsibility attributions by intensifying overall levels of blame, while simultaneously deflecting blame away from the executives responsible for managing the firm and diffusing it to other factors, including the state of the economy, the government, and individual consumers.

Task-Invariant Brain Responses To The Social Value Of Faces., Alex Todorov, Chris Said, Nicholas Oosterhof, Andrew Engell

Andrew Engell

‘Properly, With Love, From Scratch’: Jamie Oliver’S Food Revolution, K. Valentine Cadieux

K. Valentine Cadieux

Autism Spectrum Traits In The Typical Population Predict Structure And Function In The Posterior Superior Temporal Sulcus., Elisabeth Von Dem Hagen, Lauri Nummenmaa, R Yu, Andrew Engell, Michael Ewbank, Andy Calder

Andrew Engell

Global Comparison Of Warring Groups In 2002-2007: Fatalities From Targeting Civilians Vs. Fighting Battles., M Hicks, U Lee, R Sundberg, M Spagat

Madelyn Hsiao-Rei Hicks

BACKGROUND:

Warring groups that compete to dominate a civilian population confront contending behavioral options: target civilians or battle the enemy. We aimed to describe degrees to which combatant groups concentrated lethal behavior into intentionally targeting civilians as opposed to engaging in battle with opponents in contemporary armed conflict.

METHODOLOGY/PRINCIPAL FINDINGS:

We identified all 226 formally organized state and non-state groups (i.e. actors) that engaged in lethal armed conflict during 2002-2007: 43 state and 183 non-state. We summed civilians killed by an actor's intentional targeting with civilians and combatants killed in battles in which the actor was involved for total fatalities …