ABC  Vol.6 No.4 , August 2016
A Model of Hormonal and Environmental Involvement in Growth and Sex Differentiation in European Eel (Anguilla Anguilla)
Abstract: Growth in vertebrates is a complex interaction involving the development of cells, tissues and organs. Hormones regulating growth during maturation are involved mainly in the interaction between the somatic axis and the reproduction of brain-pituitary axes. Based on the results of hormone and gene transcriptions, the secretion and treatment controlling both the somatic axis and the gonadotropic axis were affected, directly or indirectly, by the environment parameter through hormones that were studied in my laboratory. A model was proposed for sex differentiation and gonadal development correlating to the growth of European eel (Anguilla anguilla). A high growth variation is affected by the environment. At a low density of eels, the gonadotropin-releasing hormone (GnRH) affected the secretion follicle stimulation hormone (FSH) in the pituitary, steroidogenesis and aromatase (CYP19) synthesis, and the 17β-estradiol (E2) from 11-ketotestosterone (Kt-11) causing ovary development. The ovary secretion E2 affecting the ade-nylate cyclase-activating polypeptide (PACAP), growth hormone (GH) and the insulin-like growth factor (IGF) stimulated rapid growth in females. On the other hand, a high density of eels caused the pituitary gland to secrete FSH at a lower level, and CYP19 was not synthesized in the gonads. The secretion of Kt-11 affected differentiation to testis, which inhibits the somatic axis in reducing growth rate.
Cite this paper: Degani, G. (2016) A Model of Hormonal and Environmental Involvement in Growth and Sex Differentiation in European Eel (Anguilla Anguilla). Advances in Biological Chemistry, 6, 141-145. doi: 10.4236/abc.2016.64012.

[1]   Tesch, F. (1977) The Eel Biology and Management of Anguillid Eel. Chapman and Hall, London.

[2]   Degani, G. and Levanon, D. (1983) The Influence of Low Density on Food Adaptation, Cannibalism, and Growth of eels [Anguilla anguilla (L.)]. The Israeli Journal of Aquaculture-Bamidgeh, 35, 53-60.

[3]   Panfili’, J. and Ximénès, M.-C. (1994) Sources of Variation in Growth of the European Eel (Anguilla anguilla) Estimated from Otoliths. Canadian Journal of Fisheries and Aquatic Sciences, 51, 506-515.

[4]   Tesch, F.W. (1978) Telemetric Observations on the Spawning Migration of the Eel (Anguilla anguilla) West of the European Continental Shelf. Environmental Biology of Fishes, 3, 203-209.

[5]   Tesch, F.W. (1980) Occurrence of Eel Anguilla anguilla Larvae West of the European Continental Shelf, 1971-1977. Environmental Biology of Fishes, 5, 185-190.

[6]   Tesch, F.W. (1982) The Sargasso Sea Eel Expedition 1979. Helgolander Meeresunsters, 35, 263-277.

[7]   Tesch, F.W. (1989) Changes in Swimming Depth and Direction of Silver Eels (Anguilla anguilla L.) from the Continental Shelf to the Deep Sea. Aquatic Living Resources, 2, 9-20.

[8]   Tesch, F.W. (2003) The Eel. Blackwell Science, Oxford.

[9]   Ginneken, V.V. (2005) The European Eel (Anguilla anguilla, Linnaeus), Its Lifecycle, Evolution and Reproduction. Fish Biology and Fisheries, 15, 367-398.

[10]   Degani, G. and Gallagher, M.L. (1995) Growth and Nutrition of Eels. Laser Pages Publishing, Israel.

[11]   Degani, G., Tzchori, I., Yom-Din, S., Goldberg, D. and Jackson, K. (2003b) Growth Differences and Growth Hormone Expression in Male and Female European Eels [Anguilla anguilla (L.)]. General and Comparative Endocrinology, 134, 88-93.

[12]   Degani, G. and Gallagher, M.L. (1986) The Influence of 3,3’,5 Triiodo-L Thyronine on Growth, Survival and Body Composition of Slow Growing Development Elvers (Anguilla anguilla (L.)). Comparative Biochemistry and Physiology, 84A, 7-11.

[13]   Degani, G. and Dosoretz, C. (1986) The Effect of 3,3’,5-Triiodo-L-Thyronine and 17-Alpha-methyltestosterone on Growth and Body Composition of the Glass Stage of the Eel (Anguilla anguilla L.). Fish Physiology and Biochemistry, 1, 145-151.

[14]   Degani, G. and Gallagher, M.L. (1985) Effects of Dietary 17-I-Methyltestosterone and Bovine Growth Hormone on Growth and Food Conversion of Slow and Normally Growing Amercanelvers (Anguilla rostrata). Canadian Journal of Fisheries and Aquatic Sciences, 42, 610-629.

[15]   Montero, M., Yon, L., Rousseau, K., Arimura, A., Fournier, A., Dufour, S. and Vaudry, H. (1998) Distribution, Characterization, and Growth Hormone-Releasing Activity of Pituitary Adenylate Cyclase-Activating Polypeptide in the European Eel, Anguilla Anguilla. Endocrinology, 139, 4300-4310.

[16]   Kazeto, Y., Kohara, M., Miura, T., Miura, C., Yamaguchi, S., Trant, J.M., Adachi, S. and Yamauchi. K. (2008) Japanese Eel Follicle-Stimulating Hormone (Fsh) and Luteinizing Hormone (Lh): Production of Biologically Active Recombinant Fsh and Lh by Drosophila S2 Cells and Their Differential Actions on the Reproductive Biology. Biology of Reproduction, 79, 938-946.

[17]   Aroua, S., Maugars, G., Jeng, S.R., Chang, C.F., Weltzien, F.A., Rousseau, K. and Dufour, S. (2012) Pituitary Gonadotropins FSH and LH Are Oppositely Regulated by the Activin/Follistatin System in a Basal Teleost, the Eel. General and Comparative Endocrinology, 175, 82-91.

[18]   Colombo, G., Romeo, G.G., Giovannini, G., Pelizzola, D., Catozzi, L. and Piffanelli, A. (1987) Testis Cytological Structure, Plasma Sex Steroids, and Gonad Cytosol Free Steroid Receptors of Heterologous Gonadotropin (HCG)- Stimulated Silver Eel, Anguilla anguilla L. General and Comparative Endocrinology, 65, 167-178.

[19]   Degani, G. (1985) The Influence of 17-α-Methyltestosterone on Body Composition of Eels (Anguilla Anguilla (L.)). Aquaculture, 50, 23-30.

[20]   Degani, G. and Kushnirov, D. (1992) Effects of 17β-Estradiol and Grouping on Gender Determination of European Eels. Progressive Fish-Culturist, 54, 88-91.<0088:EOEAGO>2.3.CO;2

[21]   Tzchori, I., Degani, G., Elisha, R., et al. (2004) The Influence of Phytoestrogens and Oestradiol-17β on Growth and Sex Determination in the European Eel (Anguilla anguilla). Aquaculture Research, 35, 1213-1219.

[22]   Colombo, G. and Grandi, G. (1990) Gonad Sex Differentiation of Anguilla anguillaby Sex Steroid. International Reviews in Hydrobiology, 75, 763-773.

[23]   Geffroy, B. and Bardonnet, A. (2015) Sex Differentiation and Sex Determination in Eels: Consequences for Management. FISH and FISHERIES, 17, 375-398.

[24]   Kushnirov, D. and Degani, G. (1991) Growth Performance of European Eel (Anguilla anguilla) under Controlled Photo Cycle and Shelter Availability. Aquaculture Engineering, 10, 219-226.

[25]   Levy, G. and Degani, G. (2013) The Role of Brain Peptides in the Reproduction of Blue Gourami Males (Trichogastertrichopterus). Journal of Experimental Zoology Part A: Ecological Genetics and Physiology, 319, 461-470.

[26]   Yaron, Z., Gur, G., Melamed, P., Rosenfeld, H., Elizur, A. and Levavi-Sivan, B. (2003) Regulation of Fish Gonadotropins. International Review of Cytology, 225, 131-185.

[27]   Levy, G. and Degani, G. (2012) Involvement of GnRH, PACAP and PRP in the Reproduction of Blue Gourami Females (Trichogaster trichopterus). Journal of Molecular Neuroscience, 48, 603-616.

[28]   Levy, G. and Degani, G. (2011) Evidence of a Reproduction-Related Function for Pituitary Adenylate Cyclase-Acti vating Polypeptide-Related Peptide in an Anabantidae Fish. Journal of Molecular Endocrinology, 46, 101-110.

[29]   Levy, G., Gothilf, Y. and Degani, G. (2009) Brain Gonadotropin Releasing Hor-mone3 Expression Variation during Oogenesis and Sexual Behavior and Its Effect on Pituitary Hormonal Expression in the Blue Gourami. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 154, 241-248.

[30]   Degani, G. (1986) Effect of Combined Dietary 17-β-Estradiol and 17-α-Methyltestosterone on Growth and Body Composition of European Eels (Anguilla anguilla). Aquaculture, 59, 169-175.

[31]   Tzchori, I., Degani, G., Hurvitz, A. and Moav, B. (2004) Cloning and Developmental Expression of the Cytochrome P450 Aromatase Gene (CYP19) in the European Eel (Anguilla anguilla). General and Comparative Endocrinology, 138, 271-280.

[32]   Degani, G., Jackson, K., Gold-berg, D., Sarfati, R. and Avtalion, R.R. (2003) βFSH, βLH and Growth Hormone Gene Expression in Blue Gourami (Trichogaster trichopterus, Pallas 1770) during Spermatogenesis and Male Sexual Behavior. Zoological Science, 20, 737-743.

[33]   Degani, G. and Abraham, M. (1992) Effect of Insulin in the Diet on the Growth of European Eels (Anguilla anguilla (L.). Fish Physiology and Biochemistry, 10, 223-227.

[34]   Moriyama, S., Ayson, F.G. and Kawauchi, H. (2000) Growth Regulation by Insu-lin-Like Growth Factor-I in Fish. Bioscience, Biotechnology, and Biochemistry, 64, 1553-1562.

[35]   Moriyama, S., Yamaguchi, K., Takasawa, T., Chiba, H. and Kawauchi, H. ( 2008) Identification of Two Insulin-Like Growth Factor IIs in the Japanese Eel, Anguilla japonica: Cloning, Tissue Distribution, and Expression after Growth Hormone Treatment and Seawater Acclimation. Comparative Biochemistry & Physiology Part B: Biochemistry & Molecular Biology, 149, 47-57.