Cathepsin L in eggs and larvae of perch Perca fluviatilis: variations with developmental stage and spawning period

• Published in: Fish physiology and biochemistry 1999-07, Vol.21 (1), p.59-64
• Main Authors: Kestemont, P, Cooremans, J, Abi-ayad, A, Mélard, C
• Format: Article
• Language: English
• Subjects: Aquaculture; Developmental stages; Eggs; Embryonic growth stage; Freshwater; Hatching; Larvae; Perca fluviatilis; Spawning
• ISSN: 0920-1742; 1573-5168
• DOI: 10.1023/A:1007714314072

This study describes changes in cathepsin L activity during early development in Eurasian perch (Perca fluviatilis) and determines to which extend a precocious proteolysis of the yolk reserves by activated cathepsin L could be involved in the seasonal decline of egg and larval quality. During embryogenesis and early larval stages, samples were collected for determination of fertilization and hatching rates, assays of cathepsin L activity, and evaluation of larval resistance to stress (osmotic shock and fasting). Cathepsin L activity increased significantly during the embryonic development, reaching a maximum of 177.1±12.3 nmol min^sup -1^mg fresh weight^sup -1^ on day 1 post-hatching and significantly decreasing on day 3. Activity increased significantly during the spawning season and individual variations between egg strands became very high during the second half of the spawning period. An inverse relationship was established between the cathepsin L activity in 7-day old eggs and the decrease of hatching rate. A negative exponential regression was calculated between the cathepsin L activity of eggs and the resistance of corresponding newly-hatched larvae to osmotic shock. Resistance to fasting was significantly reduced in larvae from eggs with cathepsin L activity higher or lower than 20 nmol min^sup -1^ mg^sup -1^ (lethal time^sub 50^=4.7±0.7 and 3.5±0.4 days, respectively). The involvement of cathepsin L in the degradation of yolk reserves and its potential consequences on the quality of perch eggs and larvae are discussed in relation to results reported in salmonid fishes.[PUBLICATION ABSTRACT]