Untitled

Abstract

ABSTRACT:We aimed to determine the vitellogenin gene expression in response to 17β-estradiol (E2) treatment in livers of immature female Chinese edible frogs (Hoplobatrachus rugulosus). Frogs reared during rainy or dry seasons were intramuscularly injected daily with E2 at doses of 0, 50, 500, or 5000 µg/kg body weight for five days. During the rainy season, treatment with E2 within the dose range studied significantly decreased the vitellogenin gene transcript levels compared to those of the control. In contrast, during the dry season, treatment with E2 at all doses tended to increase the vitellogenin gene transcript levels. The endogenous plasma E2 levels in frogs reared during the rainy season were higher than those reared during the dry season. There was no significant difference in liver-somatic index or gonadosomatic index among the treated frogs during the rainy season. However, during the dry season, the 500 µg/kg E2 treatment significantly increased the frog liver-somatic index. The hepatocytes from the dry season frogs appeared smaller and flatter. The histology of ovaries from rainy season frogs showed that the oocytes were bigger and of several stages. We therefore concluded that the injection of E2 into immature female H. rugulosus may stimulate vitellogenesis if administered during the dry season, when the endogenous E2 is lower. This knowledge could be used as a basis for inducing precocious maturation or mating of H. rugulosus outside the breeding season.

Gonadal sex differentiation of rice field frog hoplobatrachus rugulosus (wiegmann, 1834)

“…Also, it can be manipulated in laboratory and provides a large number of offspring in a short period of time. Therefore, it has been used as an experimental animal in many fields of biological research (Khonsue and Thirakhupt, 2001;Schmalz and Zug, 2002;Bain and Truong, 2004;Ratanasaeng et al, 2008;Hasan et al, 2012). In environmental research, the abnormalities in its somatic development and reproductive system have been used for evaluating the effect of environmental changes and xenobiotic contamination (Katawutpoonphan, 2008;Ruamthum et al, 2011;Trachantong et al, 2013;Tang et al, 2020).…”

“…Taxonomic studies as well as life history of this species is still needed to be done in different populations throughout their distribution range. H. rugulosus has been used as an experimental animal for basic biological studies in Thailand such as in taxonomic diversity and geographic variation (Khonsue and Thirakhupt, 2001;Schmalz and Zug, 2002;Bain and Truong, 2004;Hasan et al, 2012), physiology (Ratanasaeng et al, 2008), behavior (Wei et al, 2011) and pathology (Satetasit et al, 2009;Sailasuta et al, 2011). Furthermore, it has also been used in studies of environmental endocrine disrupting effects on the metamorphosis and gonadal development (Ruamthum et al, 2011;Trachantong et al, 2013).…”

“…As an experimental animal, H. rugulosus also plays a key role in many fields, such as biodiversity and geographic variation (Khonsue and Thirakhupt, 2001;Schmalz and Zug, 2002;Bain and Truong, 2004;Hasan et al, 2012) and the taxonomic study of phylogenetic relationships (Pansook et al, 2012) and cryptic species complexes (Yu et al, 2015). In physiology, this species has been used as a model for studying reproductive systems (Ratanasaeng et al, 2008), including the effects of environmental endocrine disruptors (Ruamthum et al, 2011;Trachantong et al, 2013). Although there have been a number of reports using H. rugulosus, there is still no information about the species' gonadal development.…”