Pheromone signaling

Touch Off a Fight

Science Signaling  01 Mar 2011:
Vol. 4, Issue 162, pp. ec61
DOI: 10.1126/scisignal.4162ec61

Pheromones regulate various animal behaviors, including male aggression that is associated with mating. During their annual spawning gatherings, females deposit fertilized egg masses on the ocean floor and may mate many times during the spawning period. Male squid who are visually attracted to fertilized egg masses approach them and touch them with their heads and tentacles. Physical contact with the eggs triggers fighting behaviors that include arm raising, fin beating, and chasing, lunging at, and grappling with other males. This transition from schooling to fighting behaviors continues until spawning ends. Cummins et al. used reverse-phase high-performance liquid chromatography (RP-HPLC) to identify a protein called β-microseminoprotein (β-MSP) as the egg-localized trigger for male aggression in the squid Loligo pealeii. Contact with egg capsules enclosed in clear glass flasks that had been coated with plain agarose did not elicit male aggression, but contact with eggs in flasks coated in agarose that contained recombinant β-MSP did. Although the β-MSPs of chordates are primarily known as components of seminal fluid, Loligo β-MSP was secreted by the reproductive exocrine glands of females and incorporated into the outer membranes of egg capsules as they were laid. β-MSPs are rapidly evolving proteins, and the authors hypothesize that this contact pheromone may have evolved to ensure species-specific mating where many squid species share the same range.

S. F. Cummins, J. G. Boal, K. C. Buresch, C. Kuanpradit, P. Sobhon, J. B. Holm, B. M. Degnan, G. T. Nagle, R. T. Hanlon, Extreme aggression in male squid induced by a β-MSP-like pheromone. Curr. Biol. 21, 322-327 (2011). [PubMed]