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Pigmentation Development (pigmentation + development)
Selected AbstractsPigmentation development in hatchery-reared flatfishesJOURNAL OF FISH BIOLOGY, Issue 5 2000J. A. Bolker Malpigmentation is common in hatchery-reared flatfishes, decreasing the market value of whole fish, and increasing the risk of predation for juveniles released to enhance wild stocks. Pigmentation development in flatfishes occurs in two phases. First, during embryonic and larval stages pigment cells differentiate on both sides of the body. Second, at metamorphosis larval melanophores disappear, and adult melanophores differentiate on the ocular but not on the blind side. Malpigmentation seems to result from disruptions of the second phase, and may take the form of albinism on the ocular side or darkening of the blind side. Both types of aberration may be related to aspects of the hatchery environment such as lighting, substratum, and diet. Larval nutrition appears to be a key factor and enrichment of larval diets with fatty acids and Vitamin A can greatly reduce malpigmentation rates; however, levels suffcient to prevent pigmentation defects frequently cause other abnormalities. Two developmental explanations for albinism have been proposed. The first is that differentiation of ocular-side skin follows the normal blind-side pathway and adult melanophores therefore fail to develop on the ocular side. The second hypothesis suggests that dietary deficiencies inhibit retinal development and the resulting visual defects lead to failure of a hormonal signal required for melanophore differentiation. These hypotheses may well be complementary; as yet neither has been thoroughly tested. Definitive tests will require a combination of manipulative techniques such as tissue transplantation and cell culture with nutritional, behavioural and hormonal assays. Such integrative studies will further the understanding both of normal pigmentation development and of the environmental factors that contribute to high rates of albinism in hatchery-reared flatfish. [source] Skeletal and Pigmentation Defects following Retinoic Acid Exposure in Larval Summer Flounder, Paralichthys dentatusJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2007Gabriela M. Martinez Supplementation of larval diets with vitamin A (VA) is routinely and successfully used to stimulate pigmentation development in hatchery-reared flatfishes. However, excess dietary VA can lead to high levels of its metabolite retinoic acid (RA) and has been associated with the occurrence of skeletal deformities, presumably via RA toxicity. We reared summer flounder larvae, Paralichthys dentatus, in water containing 0- to 20-nM RA to assess its effects on postmetamorphic pigmentation and on skeletal development. RA exposure disrupted pigmentation development: treated tanks had a smaller percentage of normally pigmented fish than did controls, with increased numbers of both hypo- and hyperpigmented individuals. Exposure also affected the development of several skeletal features: RA treatment correlated with a significant increase in the severity of defects in jaws, fins, hypurals, and vertebrae compared with control groups. [source] Lipid composition of malpigmented and normally pigmented newly settled yellowtail flounder, Limanda ferruginea (Storer)AQUACULTURE RESEARCH, Issue 15 2002L A Copeman Abstract The lipid composition of malpigmented (MP) and normally pigmented (NP), newly settled yellowtail flounder (Limanda ferruginea, Storer) was compared in order to elucidate a possible connection between lipids and pigmentation development. Larvae were fed commercially enriched live food for 12 weeks post hatch and then differences in lipid composition and size were analysed. NP fish were found to be significantly larger (standard length 35 mm) than MP fish (32 mm) at 100% settlement. There were higher proportions of triacylglycerols in NP fish (P = 0.01), whereas MP fish had an increased percentage of phospholipids (P = 0.01). NP fish had a higher percentage of docosahexaenoic acid (DHA) in the polar lipids of their body (P = 0.03) and total lipids of their eyes (P = 0.04). These data support previously proposed theories for the importance of DHA in pigmentation development. Principal components analysis (PCA) described the majority of the variance (77%) within the data set using just two principal components axes. PCA demonstrated that differences between body zones were greater than those between NP and MP fish within a given zone. [source] | ||||||||||