Algal pheromone:Pheromone Resources

Algal pheromone:

Algal pheromones are used for various purposes like sex-inducing, sexual reproduction, male-attractant, gamete releasing, attracting pheromones etc.

Biosynthesis of the algal pheromone fucoserratene by the freshwater diatom  Asterionella formosa  (Bacillariophyceae) (Hombeck  and Boland,1998). The fresh water diatom Gomphonema parvulum (Bacillariophyceae) produces the algal pheromones hormosirene 2 (C₁₁H₁₆) and dictyopterene A 16 (C₁₁H₁₈) from highly unsaturated eicosanoic acids like 20:5 (ω−3) 21 and 20:4 (ω−6) 14. The oxidative degradation is believed to proceed by cleavage of an intermediate 9-hydroperoxide like 6 by a hydroperoxide-lyase to yield 9-oxo-nona-(5Z.7E)-dienoic acid 8 and the corresponding C₁₁ hydrocarbon  ( Pohnert et al.,1996). The freshwater diatom Asterionella formosa (Bacillariophyceae) produces octa-1,3E,5Z-triene (6) (fucoserratene), previously identified as the sexual pheromone of the brown seaweed Fucus serratus. Fucoserratene is biosynthesised from eicosa-5,8,11,14,17-pentaenoic acid (7) by oxidative cleavage of the corresponding 12-hydroperoxy intermediate 8. The biosynthetic sequence was established using eicosa-5,8,11,14-tetraen-17-ynoic acid (18), a structural analogue of 7, which was converted to octa-1,3E-dien-5-yne (21), a structural analogue of 6, by homogenates of Asterionella Formosa (Hombeck  and Boland,1998).

Unsaturated C₈ and C₁₁ hydrocarbons act as chemical signals (chemotaxis) during sexual reproduction of many marine brown algae. One of these compounds, namely (+)-(6S)-6-(1Z-butenyl)cyclohepta-1,4-diene (=ectocarpene) is also formed as a major hydrocarbon by the flowering plant Senecio isatideus (Asteraceae). On administration of enantiospecifically labelled (8R)- or (8S)-[7,8-²H₂]trideca-3,6,9-trienoic acid instead of the natural precursor dodeca-3,6,9-trienoic acid to this plant, the artificial C₁₂ analogue of ectocarpene is formed. (Hombeck, Marc and  Boland, Wilhelm.1990).

Female gametes of the marine brown algaAnalipus japonicus secrete a complex bouquet of olefinic C₁₁-hydrocarbons. The major compound is ectocarpene, while hormosirene and dictyotene are present at levels of 2%. Although a minor constituent of the pheromone bouquet, hormosirene is 100 times more active as a male-attractant than ectocarpene (Müller et al.,1990; Kochert, 1978;Maier and  Müller,1986).

Female gametes of marine brown algae release and/or attract their conspecific males by chemical signals. The majority of these compounds are unsaturated, nonfunctionalized acyclic, and/or alicyclic C11 hydrocarbons. Threshold concentrations for release and attraction are generally observed in the range of 1-1000 pmol. The blends may contain various configurational isomers of the genuine pheromones as well as mixtures of enantiomers (Boland,1995).

Several cyclic and alicyclic C₁₁ hydrocarbons have been shown to act as gamete releasing and/or attracting pheromones during sexual reproduction of brown algae (Phaeophyceae) (Boland and Mertes,1985).

The sex-inducing pheromone of the multicellular green alga Volvox carteri is a glycoprotein that triggers development of males and females at a concentration <10⁻¹⁶ M. By differential screening of a cDNA library, two novel genes were identified that are transcribed under the control of this pheromone. Unexpectedly, one gene product was characterized as a lysozyme/chitinase, and the other gene product was shown to encode a polypeptide with a striking modular composition. This polypeptide has a cysteine protease domain separated by an extensin-like module from three repeats of a chitin binding domain. (Amon Peter et al.,1998).

References:

Amon Peter, Haas Elke, and  Sumper Manfred.1998.The sex-inducing pheromone and wounding trigger the same set of genes in the multicellular green alga Volvox. The Plant Cell, 10(5):781-789.

Boland, Wilhelm and Mertes, Karin.1985.Biosynthesis of algal pheromones. European journal of biochemistry, 147(1):83-91.

Boland, Wilhelm.1995. The chemistry of gamete attraction: chemical structures, biosynthesis, and (a) biotic degradation of algal pheromones. Proceedings of the National Academy of Sciences, 92(1):37-43.

Hombeck, Marc and  Boland, Wilhelm. Biosynthesis of the algal pheromone fucoserratene by the freshwater diatom Asterionella formosa (Bacillariophyceae). Tetrahedron, 1998, vol. 54, no 37, p. 11033-11042.

Hombeck, Marc and  Boland, Wilhelm.1990.Stereochemical studies on algal pheromone biosynthesis. European Journal of Biochemistry,191(2)453-459.

 Hombeck, M. and Boland, W.1998. Biosynthesis of the algal pheromone fucoserratene by the freshwater diatom  Asterionella formosa  (Bacillariophyceae) .Tetrahedron 54:11033–11042.

Kochert, Gary.1978. Sexual pheromones in algae and fungi. Annual Review of Plant Physiology, 29(1):461-486.

Maier, I. and  Müller, D. G. 1986.Sexual pheromones in algae. Biological Bulletin, 145-175.

Müller, D. G., Kawai, H., Stache, B., et al.1990. Sexual pheromones and gamete chemotaxis in Analipus japonicus (Phaeophyceae). Experientia, 46(5):534-536.

Pohnert, Georg et Boland, Wilhelm.1996.Biosynthesis of the algal pheromone hormosirene by the fresh-water diatom Gomphonema parvulum (Bacillariophyceae). Tetrahedron,52(30):10073-10082.