International Scholarly Research Network ISRN Endocrinology Volume 2011, Article ID 476283, 11 pages doi:10.5402/2011/476283 Research Article Expression of an Androgenic Gland-Speciﬁc Insulin-Like Peptide during the Course of Prawn Sexual and Morphotypic Differentiation Tomer Ventura, 1, 2 Rivka Manor, 1, 2 Eliahu D. Aﬂalo, 1, 2 Simy Weil, 1, 2 Isam Khalaila, 2, 3 Ohad Rosen, 1, 2 and Amir Sagi 1, 2 1 Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105, Israel 2 National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105, Israel 3 Department of Biotechnology Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105, Israel Correspondence should be addressed to Amir Sagi, sagia@bgu.ac.il Received 4 January 2011; Accepted 16 February 2011 Academic Editors: J. E. Gunton, R. Rey, and H. Ueshiba Copyright © 2011 Tomer Ventura et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The crustacean male-speciﬁc androgenic gland (AG) regulates sexual diﬀerentiation. In the prawn Macrobrachium rosenbergii, silencing an AG-speciﬁc insulin-like encoding transcript (Mr-IAG) inhibited the development of male sexual characters, suggesting that Mr-IAG is a key androgenic hormone. We used recombinant pro-Mr-IAG peptide to generate antibodies that recognized the peptide in AG cells and extracts, as veriﬁed by mass spectrometry. We revealed the temporal expression pattern of Mr-IAG and studied its relevance to the timetable of sex diﬀerentiation processes in juveniles and after puberty. Mr-IAG was expressed from as early as 20 days after metamorphosis, prior to the appearance of external male sexual characters. Mr-IAG expression was lower in the less reproductively active orange-clawed males than in both the dominant blue-clawed males and the actively sneak mating small males. These results suggest a role for Mr-IAG both in the timing of male sexual diﬀerentiation and in regulating reproductive strategies. 1. Introduction Sexual diﬀerentiation in the animal kingdom can be deﬁned as a series of events whereby the sexually indeterminate embryo progressively acquires male or female characteristics in the gonads, genital tract, and external genitalia. Sexual determination and diﬀerentiation are highly diverse pro- cesses that have evolved independently numerous times [1]. Normal sexual development in gonochoristic species consists of several sequential stages. Genetic sex, as determined by the chromosome constitution or other factors, or a combination of the two, drives the primitive gonad to diﬀerentiate into a testis or an ovary. In mammals, internal and external genitalia will subse- quently follow the male pathway in the presence of speciﬁc testicular hormones or the female pathway in their absence [2]. Anti-Mullerian hormone (AMH) and testosterone are the two key hormones produced by the testes in optimal concentrations during a critical time frame in early gestation to ensure male development. These two hormones are produced in parallel to the developmental expression of their cognate receptors in target tissues [3]. In addition to these two factors, an array of peptidic and steroidal sex hormones governs the process of sexual diﬀerentiation in all vertebrates, but with diﬀerences between and within phyla. In reptiles, for example, where temperature-dependent sexual determination predominates, and likewise in birds, sexual diﬀerentiation is primarily based on levels of circulat- ing estrogen [4–6]. This mechanism diﬀers from that in ﬁsh, in which there is a variety of diﬀerentiation processes, even in gonadogenesis itself. While in some species diﬀerentiation of the gonad into either a testis or an ovary is triggered by steroids, in other species, an undiﬀerentiated ovary- like gonad develops, which later degenerates in half of the population [7–9].