Surface pheromones

The available evidence suggests that surface pheromones mediating recognition can come from a variety of sources, and it may not be possible to make generalizations about what is a very heterogeneous phenomenon. 

Mori H, MUer A (2003) Hyperbranched (Meth)acrylates in Solution, in the Melt, and Grafted From Surfaces. 228 1-37 Mori K (2004) Pheromone Synthesis. 239 1-50 Mrksich M, see Houseman BT (2002) 218 1-44... 

Evidence has been accumulating that extracellular metabolic activity of microorganisms, mainly bacteria, occurs within skin glands and on the skin surface (Albone, 1997). Sterile human apocrine secretions do not develop the characteristic axillary odour (Shelley et al., 1953). In the salivary secretions of the boar, transformations of the pheromonal 16-androstene steroids 2. were attributed to the microbial flora (Booth, 1987). 

The other major class of extracellular LBPs of mammals is the lipocalins (Flower, 1996). These are approximately 20 kDa, P-sheet-rich proteins, performing functions such as the transport of retinol in plasma or milk, the capture of odorants in olfaction, invertebrate coloration, dispersal of pheromones, and solubilizing the lipids in tears (Flower, 1996). The retinol-binding protein (RBP) of human plasma is found in association with a larger protein, transthyretin, the complex being larger than the kidney threshold and thus not excreted, although the RBP itself may dissociate from the complex to interact with cell surface receptors in the delivery of retinol (Papiz et al., 1986 Sundaram et al., 1998). 

The site of pheromone production in flies and cockroaches that utilize hydrocarbons is similar to that of the moths. Oenocyte cells produce the hydrocarbon pheromone which is transported by lipophorin in the hemolymph to epidermal cells throughout the body for release from the cuticular surface in general [20,21]. 

Several families of moths utilize hydrocarbons or epoxides of hydrocarbons as their sex pheromone. Oenocyte cells produce hydrocarbons that are transported through the hemolymph by lipophorin [71]. In a study using arctiid moths it was shown that sex pheromone hydrocarbons are transported on the same lipophorin particle as the hydrocarbons destined for the cuticular surface [ 17]. Therefore, specific uptake of the sex pheromone hydrocarbon occurred in pheromone glands [17]. Similar findings have been found with other moths [72-74]. The mechanism behind this specific uptake of one hydrocarbon from a potential pool of other hydrocarbons is unknown. 

One of the sex pheromone components of the housefly, Musca domestica, is Z9-21 H that is found on the cuticular surface of the fly. This compound is formed by the elongation of Z9-18 CoA using malonyl-CoA and NADPH to Z15-24 CoA which is decarboxylated to form Z9-21 Hc (Fig. 3) [78-80]. Other pheromone components include an epoxide and ketone that are produced from Z9-21 Hc by a cytochrome P450 [81,82] and methyl-branched alkanes that are produced by the substitution of methylmalonyl-CoA in place of malonyl-CoA at specific points during chain elongation [83,84]. A novel microsomal fatty acid synthase is involved in production of methyl-branched alkanes in most insects [85-87]. This fatty acid synthase is different from the ubiquitous soluble fatty acid synthase that produces saturated straight chain fatty acids in that it is found in the microsomes and prefers methylmalonyl-CoA. The amino acids valine and isoleucine can provide the carbon skeletons for methylmalonyl-CoA as well as propionate [83]. 

Drosophila melanogaster is another dipteran where pheromone biosynthesis has been studied [92]. Adult sexually mature female D. melanogaster utilizes primarily Z7,Z11-27 H as a contact sex pheromone. The biosynthesis of this compound follows the biosynthesis of other hydrocarbon-derived pheromones (Fig. 3). It is biosynthesized in oenocytes [93], transported through the hemo-lymph by lipophorin [94], and deposited on the cuticle surface. Biosynthesis in the oenocytes follows a similar pathway [95] as that described for the house fly... 

As with the other insects studied that utilize hydrocarbon sex pheromones, once Z9-23 H is produced by oenocyte cells it is released into the hemolymph. Lipophorin is the transport protein that will move the hydrocarbon to cuticu-lar tissue [21]. It was found that about 24 h were required once Z9-23 H was induced to actual deposition on the cuticular surface [237]. As is the case with other insects selective partitioning of the sex pheromone was observed with relatively larger proportions of Z9-23 H being found on the cuticular surface than in other tissues [21]. 

Ista LK, Callow ME, Finlay JA, Coleman SE, Nolasco AC, Simons RH, Callow JA, Lopez GP (2004) Effect of substratum surface chemistry and surface energy on attachment of marine bacteria and algal spores. Appl Environ Microbiol 70 4151 4157 Jaenicke L, MamerFJ (1995) Lurlene, the sexual pheromone ofthe green flagellate Chlamydomonas allensworthii. Liebigs Ann 1995 1343-1345... 

Starr RC, Marner FJ, Jaenicke L (1995) Chemoattraction of male gametes by a pheromone produced by female gametes of Chlamydomonas. Proc Nat Acad Sci USA 92 641-645 Steinberg PD, de Nys R, Kjelleberg S (2002) Chemical cues for surface colonization. J Chem Ecol 28 1935-1951... 

Largely, the insect detectors for pheromones and other semiochemicals are arrays of hair-like sensilla distributed over the surface of the antennae and palps. In some species, such as scarab beetles [3, 4] and the honeybee [5], semiochemicals are received by olfactory plates. The more ubiquitous hair-like sensilla typically consist of hollow cuticular hairs (10-400 pm long, 1-5 pm thick) innervated by one or several olfactory receptor cells (neurons) and three auxiliary cells [6]. 

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