Skeletogenesis in the Persian sturgeon Acipenser persicus and its correlation with gene expression of vitamin K-dependent proteins during larval development.

Abstract

The present study describes morphological development of the skeleton in the Persian sturgeon Acipenser persicus and discusses the hypothesis that expression of genes encoding vitamin K-dependent proteins (VKDP) might be correlated with the mineralization of skeletal tissues during early development in sturgeons. Results showed that development of cartilage started just after hatching (mean ± S.D., 10·9 ± 0·7mm in total length, LT ) in the head and notochord, whereas the first signs of mineralization occurred in the dentary and in the dermopalatine and palatopterygoid elements of the upper jaw, coinciding with the onset of exogenous feeding (20·1 ± 1·5mm LT ). All branchial arch elements developed between 19·3 and 22·3mm LT , whereas mineralization was only observed in tooth plates associated with the hypobranchial 1 and gill rakers at 20·8 ± 1·5mm LT and 48·4 ± 6·4mm LT , respectively. Quantitative real-time PCR showed that transcripts of VKDP genes including bone Gla protein (bgp), matrix Gla protein (mgp) and Gla rich protein (grp) genes were significantly up-regulated during the transition to exogenous feeding, supporting hypotheses about relevance of the above-mentioned genes in chondrogenesis at early developmental stages. The strong mineralization of skeletal elements from 21·5 to 27·3mm LT (20 days post hatch) was in accordance with the maximal levels of bgp, mgp and grp expression indicating a correlation between development of the skeleton and the expression of VKDP genes. These data are important for evaluating A. persicus larval quality, understanding the influence of rearing biotic and abiotic factors on skeletogenesis and recognizing the occurrence of skeletal deformities in this species.