Molecular mechanism and the cause for high ratio of male Pengze crucian carp under high-density culture condition

Abstract:

In laboratory culture conditions, a high proportion of gynogenic Pengze crucian carp (Carassius auratus var. Pengze, Pcc) male fish occurred in F₁ progenies compared with pond culture conditions. All these F₁ progenies were bred from the same parents and obtained via artificial gynogenic method. In order to find the accurate relationship between this variant sex ratio and the culture density, gynogenic PccF₂ progenies were obtained from female PccF₁ offspring and activated by the sperm of red carp (Cyprinus carpio var. red style). They were maintained in different culture densities. Then we chose the male ones from the high-density culture groups, and the female ones from the low-density culture groups. Ovarian gene expression profiles were detected and compared between the male and female F₂ progenies respectively. Results showed that ovarian transcripts of dmrt1c, anti-Mullerian hormone (amh), aromatase (cyp19a1a) were higher than those corresponding transcripts in the testis of PccF₂ offspring both in low-density and high-density culture groups. Ovarian dmrt1a, dmrt1b, 3β-hydroxysteroid dehydrogenase (3bhsd), 11β-hydroxysteroid dehydrogenase 2(11bhsd2), 17α-hydroxylase/17,20-lyase 1(cyp17a1) and steroidogenic acute regulator protein (star) were lower than those corresponding transcripts in the testis of PccF₂ offspring both in low-density and high-density culture groups. The gene expression profiles for steroidogenic genes of PccF₂ progenies differed from different genders and densities in laboratory culture conditions, which may cause the phenomenon of high proportion of the existing male ones.