Skeletal Deformity of Scoliosis in Gilthead Seabreams (Sparus aurata): Association with Changes to Calcium-Phosphor Hydroxyapatite Salts and Collagen Fibers

Abstract

The development of skeletal deformities in seabream farming affects fish growth, survival, and production costs. Collagen distribution in different fish tissues might be correlated with swimming behavior. This study investigates whether scoliosis in seabreams is associated with changes to calcium-phosphor hydroxyapatite salts and collagen fibril morphology. Samples of decalcified vertebrae of scoliotic and non-scoliotic seabreams were examined with transmission electron microscopy and collagen micrographs were taken and analyzed. The mineral content, modulus of elasticity, and morphology of the vertebrae were also determined. The results indicated that fish with scoliosis had significant smaller mean vertebral collagen fibril diameters than the controls. Vertebrae in abdominal and caudal regions of the scoliotic seabreams appeared to be smaller than the respective vertebrae of the non-deformed seabreams. The calcium (Ca) and phosphorus (P) amounts of vertebrae of both scoliotic and non-scoliotic seabreams were not affected by the scoliosis deformity. The modulus of elasticity showed that the vertebrae from seabreams with scoliosis were more flexible than the vertebrae from seabreams without any skeletal deformity. The mechanical properties of bone are crucially dependent on collagen structure. Hence, how the vertebral column collagen of juvenile fish is related to the mechanism of deformities requires further investigation in order to provide a risk-reducing strategy to increase fish performance in aquaculture.

Gene expression analyses in malformed skeletal structures of gilthead sea bream (Sparus aurata)

“…This result demonstrated that the presence of a vertebral anomaly affects at a transcriptional level not only locally the malformed part of the tissue, but also the expression pattern of the entire column. Similarly, Boursiaki et al (2019) observed recently that the presence of scoliosis in gilthead sea bream is more frequent in the caudal region, but in those malformed fish, both the caudal and abdominal vertebrae were significantly shorter when compared to the vertebrae of a normal fish. In other studies, with Salmonidae species, malformed vertebrae have been shown to have comparable mineral content to normal vertebrae, even if differences existed at an earlier stage of the malformation process (Fjelldal et al, 2012).…”

Vertebrae Morphometric Measurement and Ca/P Levels of Different Age European Seabass (Dicentrarchus labrax)

“…Lall [15] reported that the calcium-to-phosphorus ratio in fish bones ranges from 0.7 to 1.6. The Ca/P ratio for sea bream individuals ranges from 1.79 to 2.36 [5,6,16]. According to Song et al [29] (2017) the Ca/P ratio for Japanese seabass with a mean weight of 12.5 g ranged from 1.71 to 1.79.…”

“…It includes bones, cartilage, scales, teeth, connective tissue, fin rays, tendons and all the associated stem cells [2]. The axial skeleton is made up of bones and cartilage, acts as a support for body muscles, protects organs and plays an important role in the metabolism of calcium as a source of stored ions [4][5][6]. The axial skeleton is structurally varied from a cartilage that encloses the notochord to a fully ossified vertebral column in the teleosts.…”

“…The abdominal vertebrae are located anterior to the anus and they generally bear ribs, while the caudal vertebrae are defined as the hemal spine-bearing vertebrae located posterior to the anus. According to Nowroozi et al [7], in striped bass (Morone saxatilis) the vertebral column can be divided into three regions: the cervical (vertebrae 1-4), the abdominal (vertebrae [5][6][7][8][9][10][11][12] and the caudal (vertebrae [13][14][15][16][17][18][19][20][21][22][23][24][25]. The vertebrae number in the European seabass ranges from 24 to 26, and the medial vertebral spaces range from 23 to 25 [10].…”

Distribution of deformities among cultured Sparus aurata marketed in Istanbul, Turkey

“…Various other procedures have also been used in scientific studies, such as X‐ray imaging, double staining or even computer tomography; (Boglione & Costa, 2011; Ortiz‐Delgado et al., 2014). X‐ray imaging, is a common method to detect skeletal deformities in fish (Afonso et al., 2000; Boursaki et al., 2019; Korkut et al., 2009), but mostly used in scientific research.…”