Sperm May Play Leading Role In Spreading HIV

Sperm, and not just the fluid it bathes in, can transmit HIV to macrophages, T cells, and dendritic cells (DCs), report a team led by Ana Ceballos at the University of Buenos Aires in Argentina. By infecting DCs, which carry the virus and potently pass it to T cells, sperm may play a leading role in spreading HIV. The article appears in the November 23, 2009 issue of the Journal of Experimental Medicine (online October 26).

During sexual intercourse, HIV-infected men transmit HIV through their semen, which carries free-floating virus as well as HIV-infected leukocytes. Traces of HIV have been detected on sperm as well, but the role they play in viral transmission has been a matter of debate. After all, men with vasectomies can transmit HIV. Now, Ceballos et al. show that HIV attaches to the surface of sperm and that these HIV carriers pass on the virus to DCs and other HIV targets.

Sperm express molecules known to interact with HIV’s envelope, such as heparan sulfate and mannose receptors. The authors show that HIV relies on heparan sulfate to attach to sperm, but not mannose receptors as previously predicted. Read more

Studies Suggest Males Have More Personality

Males have more pronounced personalities than females across a range of species – from humans to house sparrows – according to new research. Consistent personality traits, such as aggression and daring, are also more important to females when looking for a mate than they are to males. Research from the University of Exeter draws together a range of studies to reveal the role that sexual selection plays in this disparity between males and females.

The study shows that in most species males show more consistent, predictable behaviours, particularly in relation to parental care, aggression and risk-taking. Females, on the other hand, are more likely to vary their behaviour. They are also more likely to respond to these traits and therefore seem to be ‘choosier’ about the personality of a potential mate.

The research, which is published in the journal Biological Reviews (18 November 2009) draws on several studies, dating back to 1972. It is the latest study in a growing body of research from a University of Exeter team that links gender personality differences to sexual selection.

The authors believe sexual selection may hold the key to this variation. A concept originally developed by Charles Darwin, sexual selection is the theory that evolutionary traits can be explained by competition between one sex – usually males – for mates and by (female) mate choice. While the physical attributes resulting from sexual selection – from dazzling peacocks tails to over-sized antler horns – are well known, there has been much less of a focus on the impact on personality. Read more