부산대학교 도서관

Cheirodon interruptus is a ubiquitous small characid that inhabits the Pampean region and commonly used as bait. Its vast market is supplied from the wild population causing a significant environmental impact. In this study, we assess the effect of photoperiod on ovarian maturation in order to evaluate its potential as a tool to manipulate reproduction under artificial conditions. Four treatments in triplicate (light: dark, L: D) were tested: 24L: 0D, 12L: 12D, 0L: 24D and a progressive photoperiod corresponding to the daily photoperiod increments in wild during winter-spring transition, accelerated three times. The experiment was conducted for 45 days. Gonadosomatic index (GSI), oocyte mean diameter, vitellogenic oocyte proportions, plasma estradiol concentrations (E2), condition factor (Kn) and standard length were estimated. Values of mean GSI, oocyte diameter, vitellogenic oocyte proportions and E2 concentration were maximum in the progressive treatment indicating vitellogenesis stimulation. In turn the same parameters were minimum in the 24L: 0D, revealing the vitellogenesis inhibition. This study showed that photoperiodic regime play an important role in the onset of ovarian maturation in C. interruptus. Keywords: photoperiod, gonadal maturation, vitellogenesis, Characiforms. Cheirodon interruptus e um pequeno caracideo amplamente distribuido na regiao Pampeana e comumente usado como isca. Seu vasto mercado se abastece de populacoes silvestres causando um impacto ambiental significativo. Neste estudo, investigamos o efeito do fotoperiodo no amadurecimento do ovario para avaliar o potencial deste fator como ferramenta para manipular a reproducao em condicoes artificiais. Quatro tratamentos foram testados por triplicado (luz: escuro, L: D): 24L: 0D, 12L: 12D, 0L: 24D e um fotoperiodo progressivo que simula as mudancas das horas luz na natureza e na transicao de inverno a primavera, acelerado tres vezes. O experimento se realizou durante 45 dias. O indice gonadossomatico (GSI), o diametro medio dos ovocitos, a proporcao de ovocitos vitelogenicos, as concentracoes plasmaticas de estradiol (E2), o fator de condicao (Kn) e o comprimento padrao foram estimados. Os valores medios de GSI, o diametro dos ovocitos, as proporcoes de ovocitos vitelogenicos e a concentracao de E2 foram maximizados no fotoperiodo progressivo, indicando estimulacao de vitelogenesis. Por outro lado, esses mesmos parametros resultaram minimos no tratamento 24L: 0D, revelando um efeito inibidor da vitelogenesis. Este estudo mostrou que as variacoes de fotoperiodo exercem um papel importante no inicio vitelogenesis reprodutiva em C. interruptus. Palavras-chave: fotoperiodo, maturacao gonadal, vitelogenese, Characiformes.
1. Introduction Cheirodon interruptus (Jennyns 1842) is a small fish widely spread in South America: Argentina, Brazil, Chile (introduced) and Uruguay, belongs to Characiforms order which is extensively represented in [...]