Purification, Identification, Concentration and Bioactivity of (Z)-7-Dodecen-1-yl Acetate: Sex Pheromone of the Female Asian Elephant, Elephas maximus

Abstract

In their natural ecosystems, adult male and female Asian elephants, Elephas maximus, live separately. For several weeks prior to ovulation, female elephants release a substance in their urine which elicits a high frequency of non-habituating chemosensory responses, especially flehmen responses, from male elephants. These responses occur prior to, and are an integral part of, mating. Using bioassay-guided fractionation, quantitatively dependent on these chemosensory responses, a specific sex pheromone was isolated and purified by an alternating series of organic and/or aqueous extractions, column chromatography, gas chromatography and high-performance liquid chromatography. Using primarily 1H-proton nuclear magnetic resonance (NMR) spectrometry and gas chromatography-mass spectrometry (GC-MS) of the urine-derived pheromone and its dimethyl disulfide derivative, we determined the structure of the active compound to be (Z)-7-dodecen-1-yl acetate (Z7-12:Ac). Concentrations of Z7-12:Ac in the female urine increased from non-detectable during the luteal phase to 0.48 microgram/ml (0.002 mM) early in the follicular phase and to 33.0 micrograms/ml (0.146 mM) just prior to ovulation. Bioassays with commercially available authentic synthetic Z7-12:Ac, using 10 Asian male elephants at several locations in the US, demonstrated quantitatively elevated chemosensory responses that were robust during successive tests, and several mating-associated behaviors. Bioassays with Z7-12:Ac with adult male elephants dwelling in more natural social situations in forest camps in Myanmar revealed some differing contextual pre-mating behavioral components. The remarkable convergent evolution of this compound suggests that compounds identified in mammalian exudates that are also present in pheromone blends of insects should be re-evaluated as potential mammalian chemosignals.

Extreme expansion of the olfactory receptor gene repertoire in African elephants and evolutionary dynamics of orthologous gene groups in 13 placental mammals

“…The large repertoire of elephant OR genes might be attributed to elephants' heavy reliance on olfaction in various contexts, including foraging, social communication, and reproduction (Langbauer 2000;Rasmussen and Krishnamurthy 2000). In fact, the Asian elephant (Elephas maximus) is among the few mammalian species for which a sex pheromone has been chemically identified (Rasmussen et al 1996(Rasmussen et al , 1997. African and Asian elephants possess a specific scent gland, called the temporal gland, behind each eye, and male elephants exude an oily odoriferous secretion from the temporal gland annually during musth, which is characterized by increased aggressiveness and elevated levels of testosterone (Rajaram and Krishnamurthy 2003).…”

Estrous state influences on investigative, aggressive, and tail flicking behavior in captive female Asian elephants

“…Female Asian elephants (Elephas maximus) release a pheromone, (Z)-7-dodecen-1-yl acetate (Z7-12:Ac), in their urine that signals approaching ovulation to conspecific males [Rasmussen et al, 1997]. Herd members may eavesdrop on such signals, yet female Asian elephants show very little response to Z7-12:Ac [Rasmussen, 1998].…”

A synthesized pheromone induces upstream movement in female sea lamprey and summons them into traps

“…Vertebrate pests have never been controlled with pheromones. Studies of pheromone-mediated behavior of vertebrates in natural habitats have been limited both because relatively few vertebrate pheromones have been chemically identified (3) and because field research on this topic is often constrained by the ecology and behavior of vertebrates (4). Nonetheless, studies of the sea lamprey (Petromyzon marinus), an ancestral vertebrate and destructive invader of the Laurentian Great Lakes (5), indicate that spermiated males release a pheromone, 7␣, 12␣, 24-trihydroxy-5␣-cholan-3-one 24-sulfate (3kPZS) (6), that induces predictable movements in ovulated females in spawning streams (7).…”