Dynamics of ovarian maturation throughout the reproductive cycle of the Neotropical cichlid fish Cichlasoma dimerus (Teleostei, Cichliformes).

VARELA, MARÍA LUISA; FERREIRA, MARÍA FLORENCIA; DA CUÑA, RODRIGO HERNÁN; LO NOSTRO, FABIANA LAURA; GENOVESE, GRISELDA; MEIJIDE, FERNANDO JAVIER

CANADIAN JOURNAL OF ZOOLOGY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Año: 2017

0008-4301

In this study, we analyzed gene expression profiles, plasma steroids concentrations and gonadal morphology throughout the reproductive cycle of female Cichlasoma dimerus (Heckel, 1840), a monogamous cichlid fish exhibiting social hierarchies. Fish were analyzed at six phases encompassing their annual cycle, namely resting (during the non-reproductive period); pre-spawning, 30 hours post-spawning (ps), 4 days ps, 10 days ps and subordinate (during the reproductive period). The histological and histomorphometric analysis showed that C. dimerus exhibits asynchronous ovarian development. Similarly to resting females, subordinate females showed low gonadosomatic index, reduced expression levels of vitellogenin (vtgAb), zona pellucida (zpB), gonadal aromatase (cyp19a1A) and low levels of plasma sex steroids, thus indicating that social intimidation by dominant conspecifics elicited reproductive arrest. In reproductively active females, a direct positive correlation between plasma estradiol, vtgAb expression, the percentage of late vitellogenic oocytes and the gonadosomatic index was observed. These parameters were maximal at the pre-spawning phase, decreased at 30 h and 4 d ps, and then reached a peak on day 10 ps. Our results indicate that C. dimerus females become spawning capable after 10 days following spawning, coincidently with the shortest time interval between successive spawns recorded in captivity.