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Many teleost fishes can withstand long feed deprivation periods, either due to an eventual lack of food or because of their behavior during reproduction and/or parental care. In this work, the effects of total food restriction on the oogenesis, spermatogenesis, and reproductive hormones of the neotropical cichlid fish Cichlasoma dimerus were studied. Specifically, different pairs were isolated after having a spawning event and were feed-deprived or daily fed for 3 weeks. After that period, gonadal histology, messenger levels of genes related to reproduction (gonadotropin-releasing hormone 1, gonadotropins, and insulin-like growth factor 1) and 11-ketotestosterone plasma levels were evaluated in both groups. Food restriction did not affect the reproductive axis in females since follicular maturation and gene expression showed no differences with respect to controls. However, in males, food restriction showed a stimulatory effect on the reproductive axis, reflected in a greater number of spermatozoa in their seminiferous lobes and spermatic ducts, and in an increase in follicle stimulating hormone messenger expression. Despite the negative effect reported for many fish species, C. dimerus seems to redirect their energy reserves towards gonadal development when faced with to a feed deprivation period.

Made available in DSpace on 2018-12-11T17:29:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-02-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) This work describes gonadotropic (GtH) cells and their morphological and immunohistochemical changes during the spermatogenic cycle of Serrasalmus maculatus (continuous spermatogenesis) and Pimelodus maculatus (seasonal spermatogenesis). GtH cells, widely distributed in the proximal pars distalis of the adenohypophysis, were characterized as round-shaped cells with eccentric nucleus, and cytoplasm with basophilic secretory granules and a variable number of vacuoles for both species. Immunohistochemistry against β-follicle-stimulating hormone (Fsh) and β-luteinizing hormone (Lh) in adjacent sections showed two separated GtH-producing cell populations, and a third population where both GtHs are expressed in the same cell for both species. In the seasonal spermatogenesis of P. maculatus, GtH cells seemed to be more abundant during developing and spawning capable phases. In contrast, no cyclic changes were detected in the continuous spermatogenesis of S. maculatus, except for the strong immunoreaction for Fsh and Lh in males with intense spermiogenesis. We conclude that changes reported here might reflect the type of spermatogenic cycle (seasonal or continuous) which are under different regulatory mechanisms (environmental and internal cues) controlling the reproduction in these species. Department of Morphology Institute of Biosciences São Paulo State University UNESP Department of Cell and Developmental Biology Institute of Biomedical Sciences University of São Paulo USP Department of Physiology Institute of Biosciences University of São Paulo USP Departamento de Biologia Celular e do Desenvolvimento Instituto de Ciências Biomédicas Universidade de São Paulo, Av. Professor Lineu Prestes 1524 Department of Morphology Institute of Biosciences São Paulo State University UNESP FAPESP: 2003/11078-9

Common name: Surubim do Paraiba. Conservation status: Critically endangered in Brazilian Red List (Rosa and Lima 2005), and regionally extinct in Sao Paulo State (Sao Paulo 2008). Steindachneridion parahybae is a migratory freshwater species and critically endangered in Paraiba do Sul River Basin. Identification: maxillary barbel short, reaching or surpassing origin of pectoral-fin insertion; pectoral and adipose fins short; pelvic fin very short, never reaching anus. Ground color in alcohol light grayish, abdomen whitish, large dark brown blotches irregularly distributed over head and trunk in an irregular, vermiculated or dotted pattern (Garavello 2005). Distribution: Endemic to the Paraiba do Sul River Basin (Garavello 2005). Abundance: In the 1950 s there were some records of capture of this specie of around 1,000 kg/year just in the part of the basin (Machado and Abreu 1952) and nowadays there are no capture records in the Sao Paulo State (Sao Paulo 2008). Habitat and ecology: Freshwater benthopelagic species, prefers bottoms with sand and stones; mainly carnivorous (Moraes and Caramaschi 1993). Reproduction: S. parahybae is a migratory species ascending the rivers to reproduce during summer. Threats: (1) Construction of dams in the Paraiba do Sul River which block the reproductive migration and act as a barrier to dispersal; (2) riparian habitat destruction; (3) water pollution, due to the high industrial development of the region; and (4) fishing. Conservation action: Since 2003, the Hydrobiology and Aquaculture Unit of CESP (Paraibuna/SP), has been supporting a fish restocking program (Caneppele et al. 2004) and fisheries efforts, funded by a governmental program (ANEEL 2006) will be important to estimate the occurrence and genetic evaluation of the specie. Conservation recommendation: Establish habitat protection and monitoring riparian zone; Environ Biol Fish DOI 10.1007/s10641-009-9480-9