Mating, sex and the immune system in humans and fish.
Sexual reproduction is still an evolutionary puzzle. A female “throws away” half of her genes during meiosis, and fills up what she lost with genes from a male. To compensate for this two-fold cost of efficiency selective mate choice has to achieve at least a two-fold genetic benefit in each generation so that sexual reproduction is not lost.
Sexual selection has been proposed as one mechanism to explain the maintenance of high allelic diversity in MHC genes, called HLA in humans that control the extent of resistance against pathogens and parasites in natural populations. MHC-based sexual selection is known to involve olfactory mechanisms in fish, mice and humans. During mate choice, females of the three-spined stickleback (Gasterosteus aculeatus) use an odour-based selection strategy to achieve an optimal level of MHC diversity in their offspring, equipping them with optimal resistance towards pathogens and parasites. The molecular mechanism of odour-based mate-selection strategies has been a long-standing puzzle. We have studied the nature of this signalling system and found the highly polymorphic signal being MHC peptide ligands - the natural perfume. We can synthesise them and by adding this substance can manipulate a male's own signal with predictable effects on female preference - at least in sticklebacks. The signalling substance is the same in mice and most probably in humans. If MHC peptide ligands are the signal also in humans they could improve the biological function of commercial perfumes.
Declaration of interest: The author declares that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector