Unilateral perivertebral fibrosis associated with lordosis, kyphosis and scoliosis (LKS) in farmed Chinook salmon in New Zealand.

Vertebral column lordosis, kyphosis and scoliosis (LKS) can result in downgrading of farmed Chinook salmon Oncorhynchus tshawytscha in New Zealand. No cause of LKS has been identified. Radiography and histology were used to quantify LKS and perivertebral fibrosis in 27 fish with LKS visible at harvest and 30 visually normal fish from 3 New Zealand farms. Radiographic LKS was present in all 27 fish with LKS and in 18 of 30 fish without visible LKS. Quantification of the radiographic severity revealed significantly higher radiographic severity scores in fish with visible LKS (mean ± SD = 5.89 ± 2.41) than in fish with no visible, but radiographic LKS (1.44 ± 0.86, p < 0.001). The most frequent histological finding was unilateral perivertebral fibrosis that often extended into the horizontal septum and adjacent myomeres resulting in separation or loss of myocytes. Fibrosis was visible in all fish with LKS and in 12 of 30 fish without visible LKS. Fibrosis scores were higher in fish with visible LKS (3.32 ± 1.71) than in fish without visible LKS (0.35 ± 0.57, p < 0.001). The radiographic LKS severity scores were significantly correlated to the fibrosis scores (R2 = 0.59 p < 0.001) in the fish. Histology of other tissues revealed multifocal inflammation within muscle, peripheral connective tissues and myocardium which were considered most likely incidental in these fish. In this study, LKS was consistently and significantly associated with perivertebral fibrosis, suggesting that perivertebral fibrosis is an important process in the development of LKS. Further research to determine the cause of the fibrosis is required.

Identification of Quantitative Trait Loci Associated with the Skeletal Deformity LSK complex in Gilthead Seabream (Sparus aurata L.).

Morphological abnormalities, especially skeletal deformities, are some of the most important problems affecting gilthead seabream (Sparus aurata L.) aquaculture industry. In this study, a QTL analysis for LSK complex deformity in gilthead seabream is reported. LSK complex is a severe deformity consisting of a consecutive repetition of three vertebral deformities: lordosis, scoliosis, and kyphosis. Seventy-eight offspring from six breeders from a mass-spawning were analyzed: five full-sibling families, three maternal, and two paternal half-sibling families. They had shown a significant association with the LSK complex prevalence in a previous segregation analysis. Fish were genotyped using a set of multiplex PCRs (ReMsa1-13), which includes 106 microsatellite markers. Two methods were used to perform the QTL analysis: a linear regression with the GridQTL software and a linear mixed model with the Qxpak software. A total of 18 QTL were identified. Four of them (QTLSK3, 6, 12, and 14), located in LG5, 8, 17, and 20, respectively, were the most solid ones. These QTL were significant at genome level and showed an extremely large effect (>35%) with both methods. Markers close to the identified QTL showed a strong association with phenotype. Two of these molecular markers (DId-03-T and Bt-14-F) were considered as potential linked-to-this-deformity markers. The detection of these QTL supposes a critical step in the implementation of marker-assisted selection in this species, which could decrease the incidence of this deformity and other related deformities. The identification of these QTL also represents a major step towards the study of the etiology of skeletal deformities in this species.

Mechanical properties of sand tiger shark (Carcharias taurus) vertebrae in relation to spinal deformity.

Approximately 35% of sand tiger sharks (Carcharias taurus) in public aquaria exhibit spinal deformities ranging from compressed vertebrae and loss of intervertebral space to dislocated spines with vertebral degeneration and massive spondylosis caused by excessive mineralization both within vertebrae and outside the notochordal sheath. To identify the mechanical basis of these deformities, vertebral centra from affected (N=12) and non-affected (N=9) C. taurus were subjected to axial compression tests on an MTS 858 Bionix material testing system, after which mineral content was determined. Vertebral centra from affected sharks had significantly lower mineral content and material behavior in nearly all variables characterizing elasticity, plasticity and failure. These mechanical deficiencies are correlated with size at capture, capture method, vitamin C and zinc deficiency, aquarium size and swimming behavior in public aquaria. Non-affected C. taurus had greater stiffness and toughness even though these properties are generally incompatible in mineralized structures, suggesting that the biphasic (mineralized, unmineralized phases) nature of chondrichthyan vertebrae yields material behavior not otherwise observed in vertebrate skeletons. However, vertebral centra from non-affected sharks had lower mineral content (33%), stiffness (167 MPa), yield strain (14%) and ultimate strength (16 MPa) than other species of sharks and bony vertebrates, indicating that biomechanical precautions must be taken in the husbandry of this species.

Correlations of capture, transport, and nutrition with spinal deformities in sandtiger sharks, Carcharias taurus, in public aquaria.

A number of captive sandtiger sharks (Carcharias taurus) in public aquaria have developed spinal deformities over the past decade, ranging in severity from mild curvature to spinal fracture and severe subluxation. To determine the frequency and etiologic basis of this disease, U.S. public aquaria participated in a two-stage epidemiologic study of resident sharks: 1) a history and husbandry survey and 2) hematology, clinical chemistry, and radiography conducted during health exams. Eighteen aquaria submitted data, samples, or both from 73 specimens, including 19 affected sharks (26%). Sharks caught off the Rhode Island coast or by pound net were smaller at capture and demonstrated a higher prevalence of deformity than did larger sharks caught from other areas via hook and line. Relative to healthy sharks, affected sharks were deficient in zinc, potassium, and vitamins C and E. Capture and transport results lead to two likely etiologic hypotheses: 1) that the pound-net capture process induces spinal trauma that becomes exacerbated over time in aquarium environments or 2) that small (and presumably young) sharks caught by pound net are exposed to disease-promoting conditions (including diet or habitat deficiencies) in aquaria during the critical growth phase of their life history. The last hypothesis is further supported by nutrient deficiencies among affected sharks documented in this study; potassium, zinc, and vitamin C play critical roles in proper cartilage-collagen development and maintenance. These correlative findings indicate that public aquaria give careful consideration to choice of collection methods and size at capture and supplement diets to provide nutrients required for proper development and maintenance of cartilaginous tissue.

Vertebral column deformity and hypoxia in Salmo salar / Hipoxia relacionada a deformidad de columna vertebral en Salmo salar

Vertebral Column Deformity (VCD) is a common pathology in Chilean salmon farms, lowering the quality and commercialization of the product. Hypoxia has been related to other musculoskeletal deformities, but not to VCD. This work analyzes the morphology of the vertebral column of Salmo salar alevins, cultured under hypoxic conditions (60 percent O2 saturation in the water tanks) for different time periods after hatching (2, 4, 6 and 8 days). They are compared with their normoxic controls (100 percent O2 saturation). Using histological (H/E), and morphometric techniques, it was found that the time of exposure to hypoxia is inversely proportional to the body length, notochordal diameter and thickness of its sheath. The organic response to hypoxia was quantified by immunohistochemistry for HIF-1a as the sensor of hypoxia. Its expression increased significantly (p<0.05) in the experimental groups that exhibit VCD. Although etiology for VCD is probably multifactorial, this study allows for the conclusion that hypoxia by itself, produces VCD.

La deformidad de columna vertebral (DCV) es una patología que se presenta frecuentemente en la salmonicultura chilena, disminuyendo la calidad y comercialización del producto. La hipoxia ha sido relacionada a otras deformidades musculoesqueléticas pero no a DCV. Este trabajo analiza la morfología de la columna vertebral en alevines Salmo salar cultivados en condiciones de hipoxia (60 por ciento de saturación de O2) en diferentes momentos después de la eclosión (2, 4, 6 y 8 días) y son comparados con sus respectivos controles en normóxia (100 por ciento de saturación de O2). Utilizando técnica histológica (H/E) y morfométrica, se determinó que el tiempo de exposición a hipoxia es inversamente proporcional a la longitud corporal, diámetro notocordal y grosor de su vaina. La respuesta orgánica a hipoxia fue cuantificada mediante inmunohistoquímica contra HIF-1a como censor de hipoxia. Su expresión incrementó significativamente (p<0,05) en los grupos experimentales que presentaron DCV. Aunque la etiología de DCV es probablemente multifactorial, este estudio permite concluir que la exposición a hipoxia puede provocar DCV por sí sola.

Identification of some skeletal deformities in freshwater teleosts raised in Egyptian aquaculture.

This study examines different forms of skeletal deformities detected in fish species collected from two Egyptian aquaculture facilities during two harvest seasons in 2008. Various patterns of skeletal deformities were observed in 19 of 959 fish collected. Deformities were diagnosed using a number of techniques including clinical, radiographic, sonographic and histopathological evaluations. Observed deformities included: lordosis and kyphosis in African catfish (Clarius gariepenius); lateral projection of the mandible, parrot-like head, scoliosis, kyphosis, lordosis and fusion of dorsal with anal fins in Nile tilapia (Oreochromis niloticus); and stump body, scoliosis and mandibular joint deformity in common carp (Cyprinus carpio). Relative incidences of deformities in fish from a facility located in the Sharkia province were 5.12%, 2.66% and 2.85% among catfish, Nile tilapia and common carp, respectively. At a second fish farm located in the Kafr Elsheikh province, the incidences of deformities were 1.02%, 1.55% and 0% among catfish, Nile tilapia and common carp, respectively. Some of the deformities were confirmed using both sonographic and histopathological evaluations. The reasons for the observed deformities could not be definitively determined, but possible aetiologies are discussed.

The mutant guppy syndrome curveback as a model for human heritable spinal curvature.

STUDY DESIGN: This study investigated the morphology, pathogenesis, and inheritance of idiopathic-like spinal curvature in the guppy syndrome, curveback. OBJECTIVE: To determine whether curveback could be applied as a model for the primary factors that contribute to heritable spinal curvature in humans, specifically, the etiopathogenesis of human familial idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Although a genetic basis is accepted, phenotypic complexity and the lack of an animal model with noninduced curvature have made identification of idiopathic scoliosis etiology difficult. It is well established that humans and fish share many genes with similar tissue and temporal expression characteristics, and comparisons between human and fish genomes have proven to be valuable for understanding the genetics of diseases affecting humans. METHODS: The curveback lineage of guppies was constructed from a single curved male crossed to a normal female. Offspring (103) from the original cross were scored from birth until death for the presence and magnitude of spinal curvature. Genetic architecture was investigated through selective inbreeding, analysis of the distribution of curve magnitude in the mature population, and assessment of curve dynamics during development. Computed tomography assessed vertebral detail. RESULTS: Computed tomography reveals that vertebral breakage or fusion is not associated with the curveback syndrome. Inbreeding demonstrates a strong genetic influence on curveback, and the distribution of curve magnitude among adult fish suggests polygenic inheritance. There is a female bias for curves of high magnitude and curves that resolve before maturity. There is developmental variability for the age of curve onset, curve progression, and final curve magnitude. CONCLUSIONS: Observed parallels between the curveback syndrome and human idiopathic scoliosis suggest that the guppy model is an unexploited resource for the identification of primary etiological factors involved in curvature. As models for biomedical research, teleosts offer great potential regarding spinal stability and deformity.

Spinal deformity in a sandtiger shark, Carcharias taurus Rafinesque: a clinical-pathological study.

The present study investigated spinal deformity in a captive sandtiger shark and describes the clinical and histopathological features of the lesion. Clinically, the shark presented a marked spinal curvature in the region between the pectoral girdle and cranial dorsal fin. Radiographic studies revealed scoliosis and kyphosis of the vertebral column with a modification of the basic structure of five vertebrae. Post-mortem examination confirmed the results of radiographic studies and histological examination showed remodelling and cartilaginous proliferation of the vertebral bodies together with necrosis, haemorrhage and signs of a local chronic inflammatory response extending to the surrounding muscle. Different aetiologies are proposed and discussed but nutritional imbalance (dietary vitamin deficiency) and/or traumatic injury are considered the most likely contributing factors.

Spinal curvature of cultured Japanese mackerel Scomber japonicus associated with a brain myxosporean, Myxobolus acanthogobii.

Skeletal deformities were found in the cultured Japanese mackerel Scomber japonicus. External and radiographical observations showed the deformed fish to exhibit a dorso-ventral spinal curvature (kyphosis) without fracture or dislocation of the vertebrae. Numerous myxosporean cysts, ca. 0.3 to 1.0 mm in diameter, formed in the 4th ventricle, the cavity of the optic tectum, the surface of the olfactory lobe and bulb, the optic lobe and the inferior lobe of the brain. Spore morphology and molecular analysis of the small subunit ribosomal RNA gene sequence identified the myxosporean parasite as Myxobolus acanthogobii, a parasite which also causes scoliosis in yellowtail Seriola quinqeradiata. Histopathological observation showed that the myxosporean cysts were encapsulated within the host's collagenous layer although some had disintegrated to disperse mature spores into the cranial cavity. Occasionally, lymphocytic infiltration and local granulomatous inflammation were found to be associated with spore dispersion.