Month: September 2022

THE FLY IN THE OINTMENT. “Male tilapia sex pheromones have multiple effects.” https://lnkd.in/drx5_4e View in LinkedIn

GENES STIMULATED. “Sex pheromones in the urine of dominant male Mozambique tilapia (Oreochromis mossambicus) deter subordinate males, attract females and prime ovulation in females. Two steroid glucuronates (5β-pregnane-3α,17α,20β-triol 3-glucuronate and its 20α-epimer) are produced in large quantities by dominants and are the most potent urinary odorants to females. They act via (a) specific and common olfactory receptor(s) on the females’ endocrine axis, stimulating production and release of 17,20β-P, the major oocyte maturation-inducing hormone in teleost fishes. This leads to the ripening of the oocytes and (likely) synchronizes spawning.” https://lnkd.in/drx5_4e View in LinkedIn

NUANCED RESPONSES. “Pheromones elicit stereotyped behavioural and/or physiological responses but these are modulated by context, time of day, and many other factors including the receiver’s genetics, age, sex, hormonal state, dominance status, and recent experience.” https://lnkd.in/drx5_4e View in LinkedIn

PRIMED WHEN LOADED. “Male Agrotis moths do not respond to female sex pheromone for up to 24 hours after mating. Even though pheromone still stimulates the olfactory sensory neurons in the male moth’s antennae, the brain response is blocked until enough time has elapsed for the male to have replenished his accessory protein stores to go with his sperm. Male hamsters only respond to female pheromone if they are well fed, giving them sufficiently high blood testosterone levels in their hypothalamus.” https://lnkd.in/drx5_4e View in LinkedIn

CONDITIONS PRECEDENT. “While, typically, pheromones do not need to be learnt, if development is interfered with by an experimenter, previously invisible dependencies can be revealed. For example, honeybee workers need early exposure to queen mandibular pheromone in order to be attracted to it when they attend the queen as older workers.” https://lnkd.in/drx5_4e View in LinkedIn

CLASSIC ODORANTS. “Pheromones are the same in all sexually mature males, for example, of a species. It is the consistency in these molecules between individual males in a population which allows them to be identified as a pheromone. Some males may produce more of the pheromone and thus may be more attractive to females: well-fed male voles with high testosterone levels produce more pheromone.” https://lnkd.in/drx5_4e View in LinkedIn

LEARNED ODORANTS. “Pheromones are one kind of semiochemical, chemicals giving information. Another kind of semiochemical, signature mixtures, are the basis of individual recognition based on learning the different chemical profiles of individuals, allowing familiar and unfamiliar animals to be distinguished.” https://lnkd.in/drx5_4e View in LinkedIn

BOMBSHELL. “With few exceptions, learning underlies all recognition.” https://lnkd.in/drx5_4e View in LinkedIn

INDIVIDUAL BIOMARKERS. “It is worth separating the concepts of pheromones and signature mixtures (it was a mistake in my 2003 book to combine them). It is precisely because individuals have different odour profiles that these can be learnt and used to distinguish different animals.” https://lnkd.in/drx5_4e View in LinkedIn

SO ENDS this first of two weekends on the subject of pheromones. Universal, complex, and very diverse, these molecules operate in addition to other modes of communication, layered on top as a primary, perhaps more primitive, sense. It is stunning that sexual attraction is so determined by these molecules, which, in turn, reflect the biological fitness of the partner. And probably not far disconnected from the molecules of quorum sensing used by bacteria. View in LinkedIn