Cockroaches hydrocarbon biosynthesis

Studies with widely diverse insect species, including both the American cockroach and the housefly, have established that the major site of cuticular hydrocarbon biosynthesis is the cells associated with epidermal tissue or the peripheral fat body, particularly the oenocytes (J[). 

Biosynthesis of methyl branched hydrocarbons of the German cockroach Blattella germanica (L.) (Orthoptera, Blattellidae). Insect Biochemistry 20 149-156. 

Gu, X., Quilici, D., Juarez, P, Blomquist, G. J. and Schal, C. (1995). Biosynthesis of hydrocarbons and contact sex pheromone and their transport by lipophorin in females of the German cockroach (Blattella germanica). Journal of Insect Physiology 41 257-267. 

A microsomal FAS was implicated in the biosynthesis of methyl-branched fatty acids and methyl-branched hydrocarbon precursors of the German cockroach contact sex pheromone (Juarez et al., 1992 Gu et al., 1993). A microsomal FAS present in the epidermal tissues of the housefly is responsible for methyl-branched fatty acid production (Blomquist et al., 1994). The housefly microsomal and soluble FASs were purified to homogeneity (Gu et al., 1997) and the microsomal FAS was shown to preferentially use methylmalonyl-CoA in comparison to the soluble FAS. GC-MS analyses showed that the methyl-branching positions of the methyl-branched fatty acids of the housefly were in positions consistent with their role as precursors of the methyl-branched hydrocarbons. 

Chase J., Jurenka R. J., Schal C., Halamkar P. P. and Blomquist G. J. (1990) Biosynthesis of methyl branched hydrocarbons in the German cockroach Blattella germanica (L.) (Qrthoptera, Blattellidae). Insect Biochem. 20, 149-156. 

Schal C., Gu X., Burns E. L. and Blomquist G. J. (1994) Patterns of biosynthesis and accumulation of hydrocarbons and contact sex pheromone in the female German cockroach, Blattella germanica. Arch. Insect Biochem. Physiol. 25, 375-391. 

Insects utilize propionate and methylmalonate in the biosynthesis of ethyl branched juvenile hormones and methyl branched cuticular hydrocarbons. The sources of propionate and methylmalonate in some insects appear to differ from those in mammals. Succinate is the precursor of propionate and methylmalonate in a termite, whereas valine and probably other amino acids are the sources of propionate and methylmalonate in several other species. An unusual pathway for propionate metabolism has been shown to occur in insects and it may be related to the absence or low levels of vitamin B found in many species. Propionate is converted directly to acetate with carbon 1 of propionate lost as C02> carbon 2 of propionate becoming the methyl carbon of acetate and carbon 3 of propionate becoming the carboxyl carbon of acetate. This pathway suggested the possibility that 2-fluoropropionate might be selectively metabolized in insects to the toxic 2-fluoro-acetate. However, preliminary data indicate that 2-fluoropropionate is not toxic to the housefly or the American cockroach. 

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