Skeletal anomalies in rearedEuropean fish larvae and juveniles. Part 1: normal and anomalous skeletogenic processes

Abstract

This critical review summarizes the knowledge about fish skeletal tissues and inherent normal and anomalous development. Particular emphasis is given to existing literature on reared European fishes. The aim was to identify the main gaps of knowledge that require to be filled, in order to precociously identify anomalous developmental patterns that lead to skeletal anomalies in reared finfish larvae and juveniles. The review also aims to extend our knowledge about the factors that are possibly involved in the onset of skeletal anomalies. The final goal is the optimization of the morphological quality of farmed juvenile fish.

Normal and histopathological organization of the opercular bone and vertebrae in gilthead sea bream Sparus aurata

“…Previous studies have indicated that skeletal anomalies are mainly induced in early stages of development (i.e. during embryonic and larval periods), occurring long before osteological deformities are externally visible (Daoulas et al 1991, Koumoun douros et al 1997a,b, Gavaia et al 2009, Boglione et al 2013b. Nevertheless, skeletal deformities could also be in duced at later stages during the nursery phase (Boglione et al 2013a).…”

“…Fish skeletogenesis involves the activity of 3 main cell types: chondrocytes, osteoblasts and osteoclasts (see review in Boglione et al 2013b). The first 2 cell types secrete the extracellular matrix proteins of the cartilage and bone, respectively, while the third type produces cathepsins, matrix metalloproteinases and tartrate-resistant acid phosphatase (TRAP), providing an acidic environment in which the mineralized matrix is broken down (Ytteborg et al 2010).…”

“…alkaline phosphatase, ALP) or non-collagenous proteins such as the matrix Gla protein (MGP) or osteocalcin (OC), signalling molecules (e.g. hedgehogs and bone morphogenetic proteins) and transcription factors (Karsenty 2001, Boglione et al 2013b. Hence, the perturbation of some of the above-mentioned factors in controlling bone development and homeostasis, as well as the incapacity of homeorhetic mechanisms to compensate for stressful environmental conditions, may disrupt skeletogenesis, ultimately leading to the appearance of skeletal deformities (Boglione et al 2013a).…”

“…Hence, the perturbation of some of the above-mentioned factors in controlling bone development and homeostasis, as well as the incapacity of homeorhetic mechanisms to compensate for stressful environmental conditions, may disrupt skeletogenesis, ultimately leading to the appearance of skeletal deformities (Boglione et al 2013a). With the exception of environmental contaminants and pathogens (which are generally controlled under rearing conditions), different studies suggest that unfavourable environmental biotic and abiotic conditions, inappropriate nutrition and/ or genetic factors are the most probable causative agents of skeletal abnormalities in reared fish (reviewed in Boglione et al 2013b). Previous studies have indicated that skeletal anomalies are mainly induced in early stages of development (i.e.…”

“…Although the improvement and refinement of rearing techniques have considerably reduced the frequency of these types of deformities (Boglione et al 2013a), lordosis and kyphosis are still 2 of the most relevant osteological abnormalities observed in the axial skeleton of reared gilthead sea bream, while a partial and/or total lack of operculum is the most frequent anomaly affecting its cranial region (Koumoundouros et al 1997b, Boglione et al 2001, 2013b, Beraldo et al 2003, Verhaegen et al 2007, Castro et al 2008, Koumoundouros 2010, Prestinicola et al 2013). Several studies have described skeletogenesis in gilthead sea bream (Faustino & Power 1998, 1999, 2001) and the typology of fish skeletal deformities (Witten et al 2009, Boglione et al 2013b, Prestinicola et al 2013, among others) in order to better understand the phases of skeletogenesis and the effects of biotic and abiotic factors on the proper development of bone and the appearance of skeletal anomalies. Various procedures have been used as simple and rapid diagnostic tools for studying skeletal deformities in fish, such as X-rays, double staining or even computer tomography; allowing the identification of abnormal growth in different skeletal structures (see reviews in Witten et al 2009, Koumoundouros 2010, Boglione et al 2013b.…”