Pheromone functions

Mancini M., Majumder D., Chatteijee B. and Roy A.K. (1989). a2p.-Globulin in modified sebaceous glands with pheromonal functions localisation of mRNA and protein in preputial, Meibomian and perianal glands. J Histochem Cytochem 37, 148-157. 

Future work should identify further gender and season specific volatiles, to conduct a comparative study on free ranging fossas, and to perform bioassays to prove a pheromonal function of the identified substances. 

The Harderian gland, wrapped behind the eyeball, is especially prominent in rodents. It produces a variable, primarily lipid secretion and drains through the Harderian-lacrymal tract and the external nares. In Mongolian gerbils, the secretion is spread over the body during grooming (Thiessen ct ah, 1976). A pheromonal function has not been clearly established. 

For fish, it is thought that pheromones derived from hormones. Hormones are pre-existing signals produced in temporal synchrony with discrete reproductive events (Sorensen and Stacey, 1990). These hormones are readily excreted into the water. The evolution of olfactory reception mechanisms for pheromones may have been facilitated by already existing internal endocrine receptors. Sorensen and Stacey (1990) argued that for pheromonal functions to arise mutations are initially required only in the recipient. Specificity of the signal... 

Sorensen, P. W., and Stacey, N. E. (1990). Identified hormonal pheromones in the goldfish the basis for a model of sex pheromones function in teleost fish. In Chemical Signals in Vertebrates, vol. 6, ed. R. L. Doty and D. Miiller-Schwarze, pp. 302-311. New York Plenum. 

Six male specific compounds were isolated from the crucifer flea beetle, Phyllotreta cruciferae, and the same compounds plus two additional compounds were isolated from males of Aphthona flava, A. czwalinae, and A. cyparissiae. Three of the compounds were identified as (-F)-i r-himachalene, (-F)- ra w-a-himachalene (-F)-y-cadinene. Two other compounds were identified as new enantiomers of himachalene hydrocarbons that were previously identified from the fir trees, Abies alba and Abies nordmanniana. Finally, there were two himachalene alcohols and one nonsesquiterpene ketone that is a himachalene analog that were identified. The chemical and electrophysiological patterns are consistent with, but do not prove, a pheromonal function. 

A single compound that is responsible for two pheromonal functions depending upon the context and habitat... 

A single compound that has different pheromonal functions at different doses... 

Two compounds present in the opisthonotal glands, with each having separate pheromonal functions. 

In such a system, the two pheromone functions would be expected to have differing dose-response relationships, with one being sigmoid and the other convex. 

S. elongata is an example of the second category. At high doses, neral (2) acts as an alarm pheromone (Kuwahara et al, 2001), whereas at lower doses the compound attracts females (Nishimura et al., 2002). Because females of this species can reproduce parthenogenetically, the reason for this function as an attractant is not clear. Possible function may be as an aggregation pheromone. In addition, there are many other mite species in which the major component of the opisthonotal gland secretions functions as the alarm pheromone, and it is entirely possible that these compounds may be found to have additional pheromonal functions at lower doses. 

Sorensen, P. W. and Goetz, F. W., Pheromonal function of prostaglandin metabolites in teleost fish, J. Lipid Mediators, 6, 386, 1993. 

Elofsson R. and Lofqvist J. (1974) The Eltringham organ and a new thoracic gland ultrastructure and presumed pheromone function (Insecta, Myrmeleonidae). Zool. Scripta 3, 31 10. 

Danaidone proven pheromonal function (Danaus gilippus)... 

In the study by Sachse et al. (1999) it was shown that 2-heptanone evoked a specific activity pattern that differed from the corresponding alcohol or aldehyde more than functional groups differed at other chain lengths. 2-heptanone functions as a repellent scent marker in honeybees (Giurfa and Nunez, 1992 Giurfa, 1993). The pheromonal function of this substance may have paved the way for the development of an alternative specialized pathway. It cannot be excluded that non-sexual pheromones are subject to parallel processing, i.e. a second specialized pathway similar to the sexual pheromone pathways may be present in areas of the ALs not accessible for recording. 

Figure 5.1 Commonly exocrine glands found in social insects. Glands with capital lettering indicate a putative pheromonal function (author J. Billen) (with Westview Press permission).

The silk and cuticle of spiders are covered by a lipid layer. These lipid compounds protect from external damaging factors such as humidity, which modifies the cuticle s or silk s physical properties. The frequency of water exposure in natural circumstances suggests that wetting with water or similar solvents must have negligible or manageable effects on pheromone function. 

Signaling pheromones. Communication of individual identity and status is of enormous importance to most mammals, and they have evolved a variety of chemical cues and chemosensory systems to accomplish this task. Although in many instances the message conveyed is multifaceted, complicating its study, several subtypes can be identified, some of which can have overlapping pheromone function. 

Understanding of vertebrate pheromones has increased dramatically since the first cue was identified in the pig over 40 years ago. Nevertheless, pheromonal cues have only been definitively identified in just over a dozen of the approximately 58 000 species of vertebrates - much fundamental work remains. Perhaps the most significant advance in our understanding of vertebrate pheromones is the realization that most comprise multiple components and that these are found in complex mixtures that vertebrate chemosensory systems discern with precision. Further, it is now clear that the neural basis for pheromone function is mediated by multiple nervous systems (e.g., different ORNs and even organs, as in the vomeronasal system) we should expect the relatively sophisticated vertebrate brain to be employing pheromones in sophisticated and diverse manners. Indeed, the examples of both goldfish and mice show that mixture composition and context both contribute to the determination of function. 

Sarcophyton species contain diterpenes up to 10% of their dry weight, and this large quantity of secondary metabolites plays an important role in the survival of Octo-corals with defensive, competitive, reproductive, and possibly pheromonal functions. Soft corals lacking physical defense thus seem to be protected from predation by the presence of diterpene toxins in their tissue. Nearly 25 species of this genus occurring in different seawaters have been examined chemically so far, and more than 80 cembranoid diterpenes have been isolated from the Sarcophyton genus since the 1970s. 

The naive notion that insects would not be resistant to third- and fourth-generation insecticides (which rely on interference of hormone or pheromone function) was challenged first by Dyte (1972), who described populations of Tribolium castaneum that were cross-resistant to juvenile hormones. 

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