Alternative signal pathways underly fertilization and egg activation in a fish with contrasting modes of spawning
Feng Chen,
Yeke Wang,
Jun He,
Carl Smith,
Ge Xue,
Yan Zhao,
Yanghui Peng,
Jia Zhang,
Jiarui Liu,
Jun Chen,
Ping Xie
Affiliations
Feng Chen
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Yeke Wang
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Jun He
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Carl Smith
Department of Ecology and Vertebrate Zoology, University of Łódź
Ge Xue
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Yan Zhao
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Yanghui Peng
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Jia Zhang
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Jiarui Liu
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Jun Chen
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Ping Xie
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Donghu Experimental Station of Lake Ecosystems, Chinese Academy of Sciences
Abstract Background The processes of fertilization and egg activation are vital for early embryogenesis. However, while the mechanisms associated with key events during these processes differ among species and modes of spawning, the signal pathways underlying these processes are opaque for many fishes, including economically important species. Results We investigated phenotypic traits, ultrastructure and protein expression levels in the eggs of the topmouth culter (Culter alburnus), a protected and economically important freshwater fish that exhibits two spawning modes, producing semi-buoyant eggs and adhesive eggs. Unfertilized eggs of C. alburnus were examined, as well as eggs at fertilization and 30 min post fertilization. Our results showed that in semi-buoyant eggs, energy metabolism was activated at fertilization, followed by elevated protein expression of cytoskeleton and extracellular matrix (ECM)-receptor interactions that resulted in rapid egg swelling; a recognized adaptation for lotic habitats. In contrast, in adhesive eggs fertilization initiated the process of sperm-egg fusion and blocking of polyspermy, followed by enhanced protein expression of lipid metabolism and the formation of egg envelope adhesion and hardening, which are adaptive in lentic habitats. Conclusion Our findings indicate that alternative signal pathways differ between modes of spawning and timing during the key processes of fertilization and egg activation, providing new insights into the molecular mechanisms involved in adaptive early embryonic development in teleost fishes.
