Characteristics of hatching enzymes and egg envelope in cross progenies from crucian carp (Carassius auratus var.) and zebrafish (Barchydanio rerio var.)

Abstract

In distant hybridization of fishes, there is a low hatching rate of hybrid progenies. To further understand the causes of low hatchability, in this article, cross-breeding between zebrafish (ZF) and crucian carp (CC) are generated, in which the hatching rate of cross progenies (ZF♀ × CC♂, ZC) is 35.67%, while that of reciprocal cross progenies (CC♀ × ZF♂, CZ) is about zero. The structures and SDS-PAGE protein pattern of egg envelopes in hybrid early embryos are like their maternal fish, however, during the process of embryo development, some differences are detected between the CZ and CC. The hatching enzyme gene 1 (he1) nucleotide sequences from ZF and CC were 85.1% identity, while that of 99.6% identity was between the ZF and ZC, and 98.4% from CC and hybrid of CZ. There are differences in predictive protein physicochemical properties of he1 between CZ and CC, but no significant change in he1 mRNA levels during embryonic development. Our data furtherly verify that the characteristics of egg envelope and hatching enzyme in hybrid progenies are inherited from maternal fish. Moreover, there are obvious differences between CZ and maternal parent in both egg envelope and hatching enzyme during embryonic development, which are considered to be related to its low hatching rate.

Keywords

• Fish
• Distant hybridization
• Hatching
• Envelope
• Enzyme