TRENDS IN COMPARATIVE ENDOCRINOLOGY AND NEUROBIOLOGY Peptides of the Adipokinetic Hormone/Red Pigment-Concentrating Hormone Family A New Take on Biodiversity Gerd G ¨ ade Zoology Department, University of Cape Town, Rondebosch, South Africa Peptides of the adipokinetic hormone (AKH)/red pigment-concentrating hormone (RPCH) family in insects are involved in the mobilization of stored macromolecules in the fat body by activating glycogen phosphorylase or triacylglycerol lipase to in- crease the levels of circulating metabolites (trehalose, diacylglycerols, and also proline) during periods of intense muscular activity. Here I review the biodiversity of these pep- tides and outline how the 47 known bioanalogues are distributed between the different insect orders and in which species they occur. Key words: adipokinetic peptides; red pigment-concentrating peptides; arthropods; crustaceans; insects; insect orders; sequence comparison Introduction When one looks up the definition for the catch word biodiversity in any search engine, the answers will be almost as numerous as the species belonging to a species-poor insect order. The definitions will range from “the number of different species in a given habitat” (prairieu.umn.edu/), which is a rather limited view (emanating from an ecologist most likely), to “the variety of life in all forms, levels, and combinations. The term biodiversity includes genetic diversity, species diversity, and ecosystem diversity” (www.csbsju.edu/ environmentalstudies/curriculum/ greenbuildingplan/Green%20Building% 20Plan%20p12.htm), which is probably the most inclusive definition to which I will subscribe here. If we think for a moment about the products that genes encode, i.e., proteins, then it is obvious that precursors for neuropeptide hormones certainly fall into the realm of biodiversity as well. The product of Address for correspondence: Professor Gerd G¨ ade, Zoology De- partment, University of Cape Town, Private Bag ZA-7700 Ronde- bosch, South Africa. Voice: +27 2 650 3615; fax: +27 21 650 3301. gerd.gade@uct.ac.za these precursors is either one or more mature peptides, which have specific tasks to fulfill. In this review I will summarize the as- tounding diversity of neuropeptides in the phy- lum Arthropoda; I will restrict myself to the adipokinetic hormone (AKH)/red pigment- concentrating hormone (RPCH) family of pep- tides and will deal with only those peptides that have been sequenced by protein–chemical or mass spectrometric methods. I will give a very short overview first on the characteristics of this family, the mode of action, and the func- tions, but the main purpose of this article is to provide an extensive and as complete as possible database in the form of a table with all AKH/RPCH peptides characterized by se- quence so far and with taxonomic affiliation of the organisms in which these peptides originate. At a later stage, these data may become useful when constructing trees of relatedness on the basis of structural similarity of the peptides. Brief Characteristics of the Family, the Mode of Action, and Functions In this paragraph only the very essential facts on the AKH/RPCH family will be reported Trends in Comparative Endocrinology and Neurobiology: Ann. N.Y. Acad. Sci. 1163: 125–136 (2009). doi: 10.1111/j.1749-6632.2008.03625.x C  2009 New York Academy of Sciences. 125