title: Reproductive parameters of double transgenic zebrafish (Danio rerio) males overexpressing both the growth hormone (GH) and its receptor (GHR).
abstract: Growth hormone (GH) transgenesis presents a high potential application in aquaculture. However, excess GH may have serious consequences due to pleiotropic actions. In order to study these effects in zebrafish (Danio rerio), two transgenic lines were developed. The first expresses GH ubiquitously and constitutively (F0104 line), while the second expresses the GH receptor in a muscle-specific manner (Myo-GHR line). Results from the F0104 line showed accelerated growth but increased reproductive difficulties, while Myo-GHR did not show the expected increase in muscle mass. Since the two lines appeared to display complementary characteristics, a double transgenic (GH/GHR) was created via crossing between them. This double transgenic displayed accelerated growth, however reproductive parameters remained uncertain. The objective of the present study was to determine the reproductive capacity of males of this new line, by evaluating sperm parameters, expression of spermatogenesis-related genes, and reproductive tests. Double transgenics showed a strong recovery in almost all sperm parameters analyzed when compared to the F0104 line. Gene expression analyses revealed that Anti-Müllerian Hormone gene (amh) appeared to be primarily responsible for this recovery. Reproductive tests showed that double transgenic males did not differ from non-transgenics. It is possible that GHR excess in the muscle tissues of double transgenics may have contributed to lower circulating GH levels and thus reduced the negative effects of this hormone with respect to reproduction. Therefore, it is clear that GH-transgenesis technology should take into account the need to obtain adequate levels of circulating hormone in order to achieve maximum growth with minimal negative side effects.
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália km 8, Rio Grande, RS, 96203-900, Brazil.
authors.forename: Ana Cecilia Gomes
authors.initials: AC
authors.lastname: Silva
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália km 8, Rio Grande, RS, 96203-900, Brazil.
authors.forename: Daniela Volcan
authors.initials: DV
authors.lastname: Almeida
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália km 8, Rio Grande, RS, 96203-900, Brazil.
authors.forename: Bruna Felix
authors.initials: BF
authors.lastname: Nornberg
authors.affiliation: Reprodução Animal Comparada RAC, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande, Brazil.
authors.forename: Jessica Ribeiro
authors.initials: JR
authors.lastname: Pereira
authors.affiliation: Reprodução Animal Comparada RAC, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande, Brazil.|Laboratório de Reprodução Animal, Faculdade de Veterinária, Universidade Federal de Pelotas - UFPel, Pelotas, Brazil.
authors.forename: Diego Martins
authors.initials: DM
authors.lastname: Pires
authors.affiliation: Reprodução Animal Comparada RAC, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande, Brazil.|Laboratório de Reprodução Animal, Faculdade de Veterinária, Universidade Federal de Pelotas - UFPel, Pelotas, Brazil.
authors.forename: Carine Dahl
authors.initials: CD
authors.lastname: Corcini
authors.affiliation: Reprodução Animal Comparada RAC, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Rio Grande, Brazil.
authors.forename: Antonio Sergio Varela
authors.initials: AS
authors.lastname: Junior
authors.affiliation: Laboratório de Biologia Molecular, Instituto de Ciências Biológicas, Universidade Federal do Rio Grande - FURG, Av. Itália km 8, Rio Grande, RS, 96203-900, Brazil. dqmluf@furg.br.
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Marins
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified / Q000235:genetics; D018014:Gene Transfer Techniques; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics*; D018482:Muscle, Skeletal / Q000378:metabolism; D011986:Receptors, Somatotropin / Q000096:biosynthesis / Q000235:genetics*; D012098:Reproduction / Q000235:genetics*; D015027:Zebrafish / Q000235:genetics
chemical_list: D011986:Receptors, Somatotropin; D013006:Growth Hormone
keywords: Double transgenesis; GH side effects; Somatotrophic axis; Sperm; Zebrafish