Stickiness of fish eggs

Teleost eggs are surrounded by a cell membrane, called the oolemma, and an envelope, the zona radiata or chorion. Zona radiata layer consists out of an inner (zona radiata interna) and an outer layer (zona radiata externa). In many fish species, zona radiata externa is responsible for egg attachment to aquatic substrates during spawning. Egg stickiness starts always as soon as the egg contacts the water or the fertilization medium. Therefore, the present project investigates the egg stickiness phenomenon physiologically and chemically in fish. Two easy available egg types will be used, those of common carp, Cyprnuis carpio and of the Northern pike, Esox lucius. As the two species are from different systematic families also data on interspecific differences will be obtained. The properties and behaviour of the zona radiata externa in water and in saline solutions of different pH, osmolality and cation composition will be studied. The study of these parameters is necessary to understand by which factors the stickiness of the eggs is induced. Then the biochemical composition of the zona radiata externa will be analyzed qualitatively and quantitatively on proteins, amino acids, carbohydrates, amino sugars and sialic acids in the non activated (non sticky eggs) and in the sticky eggs to get data about the molecular mechanisms related with egg stickiness. This knowledge would be of value (a) to gain basic data on gamete biology, (b) for biotechnology to generate new synthetic molecules revealing high stickiness in water ("water glues"), and (c) for aquaculture to improve technologies for reduction of egg stickiness which is considered one of the most retarding obstacles of artificial propagation of these fish.

Teleost eggs are surrounded by a cell membrane, called the oolemma, and an envelope, the zona radiata or chorion. Zona radiata layer consists out of an inner (zona radiata interna) and an outer layer (zona radiata externa). In many fish species, zona radiata externa is responsible for egg attachment to aquatic substrates during spawning. Egg stickiness starts always as soon as the egg contacts the water or the fertilization medium. Therefore, the present project investigates the egg stickiness phenomenon physiologically and chemically in fish. Two easy available egg types will be used, those of common carp, Cyprnuis carpio and of the Northern pike, Esox lucius. As the two species are from different systematic families also data on interspecific differences will be obtained. The properties and behaviour of the zona radiata externa in water and in saline solutions of different pH, osmolality and cation composition will be studied. The study of these parameters is necessary to understand by which factors the stickiness of the eggs is induced. Then the biochemical composition of the zona radiata externa will be analyzed qualitatively and quantitatively on proteins, amino acids, carbohydrates, amino sugars and sialic acids in the non activated (non sticky eggs) and in the sticky eggs to get data about the molecular mechanisms related with egg stickiness. This knowledge would be of value (a) to gain basic data on gamete biology, (b) for biotechnology to generate new synthetic molecules revealing high stickiness in water ("water glues"), and (c) for aquaculture to improve technologies for reduction of egg stickiness which is considered one of the most retarding obstacles of artificial propagation of these fish.