Structural Abnormalities of Spermatozoa in Triploid Gynogenetic Crucian Carp (Carassius auratus)

Abstract

The spermatozoa of triploid gynogenetic crucian carp (Carassius auratus) (3nDTCC) possess a spermatogenesis process with a normal genetic background. However, the genetic materials of these spermatozoa do not completely inherit gynogenetic progeny in general. Understanding the intrinsic mechanism may be helpful for developing breeding strategies of gynogenetic fishes. In this study, the spermatozoa ultrastructure was systematically studied in diploid red crucian carp and 3nDTCC to demonstrate their cytological structural differences. In addition, the artificial breeding tests of 3nDTCC(♀) with different ploidy spermatozoa were performed to verify the contributions of genetic materials from 3nDTCC spermatozoa to the gynogenesis progeny. Furthermore, the mRNA expression of centriole-related genes (i.e., cep57, cetn1, rootletin, and nek2) involved in spermatozoa packaging was also determined by quantitative real-time PCR (qPCR) to illustrate the molecular expression characteristics of the spermatozoa packaging process in 3nDTCC. The results reveal the adaptive features of spermatozoa in 3nDTCC, including the loose midpiece structure, abnormal head structure, and abnormal expression of centriole-related genes, which may influence the motility of spermatozoa and make it not involved normally in the genetic composition of the gynogenesis offspring.

Atypical Centriolar Composition Correlates with Internal Fertilization in Fish

“…Of the above species, Poecilia species are used as a common reproductive model. Guppies and mollies are used to study sexual conflict [ 85 ], sperm competition [ 86 ], the impact of predation on sperm [ 87 ], and many other topics [ 88 ]. It would be important to study the precise structure of the atypical centriole in these species using more advanced electron microscopy and to study how the structure evolved in this group.…”