Biomedical subjects

J D Castell

Publications and source records attributed to J D Castell.

9 recordsLinked to original sources

PubMed1998

Distribution of alpha- and gamma-tocopherols in Atlantic salmon (Salmo salar) tissues.

Groups of Atlantic salmon parr (mean initial weight 9.5 g) were fed three diets, the first containing no tocopherol supplement, the others supplemented with either all-rac-alpha-tocopherol (A-T) or RRR-gamma-tocopherol (G-T). Tocopherol concentrations in the liver, serum, testes, kidney, brain, gill, muscle, and perivisceral fat were measured after 36 wk. Despite a higher dietary intake of G-T, compared to A-T, deposition of gamma-tocopherol (gammaT) was less efficient than of alpha-tocopherol (alphaT) in most tissues except in the perivisceral fat, an adipose tissue. In fish fed the G-T diet, the gammaT/alphaT ratio was highest in the perivisceral fat and lowest in the liver, indicating that the liver is the most discriminatory organ for retaining alphaT as compared to gammaT, and the perivisceral fat is more suitable for the storage of gammaT. A negative correlation (P < 0.01) was observed between the gammaT/alphaT ratio and the corresponding tissue phospholipid content, suggesting that gammaT is less efficiently deposited compared to alphaT in the phospholipid-rich membranes which are presumed to be the functional site for lipid antioxidants in vivo. During restricted intake of alphaT, the liver and muscle exhibited the greatest reduction of this tocopherol among the tissues analyzed. The presence of minimal alphaT in the muscle from fish fed the tocopherol-unsupplemented diet led to greater susceptibility to lipid peroxidation after frozen storage than was the case for muscle containing higher concentrations of either alphaT or gammaT. However, both alphaT and gammaT were effective stabilizers of salmon muscle lipids during frozen storage.

Animals↗

PubMed1984

The dynamics of exoskeletal-epidermal structure during molt in juvenile lobster by electron microscopy and electron spectroscopic imaging.

The exoskeletal-epidermal complex of juvenile lobsters at various stages throughout the molt cycle was examined by conventional electron microscopy, freeze-etch replicas, and electron spectroscopic imaging. This latter technique which enables the direct localization of atomic elements superimposed over morphological fine structure has been applied to this tissue complex to determine the spatial distributions and interrelationships of calcium, phosphorus, and sulphur. Chitin microfibril assembly is visualized in thin sections as occurring at the surface of apical membrane plaques which in freeze-etch replicas invariably possess a rich distribution of intramembrane particles on both P and E faces. In early stages of mineralization the exo- and endocuticular zones of the exoskeleton possess a dense Ca-containing lamellar repeat. These bands are unrelated to the helicoidal arrangement of chitin microfibrils. At later stages of development mineral deposits occur within the exocuticle and advance through to the endocuticle. These deposits align with chitin microfibrils and exhibit a helicoidal pattern. Morphological and chemical alterations associated with mineralization and demineralization of the exoskeleton are discussed.

Animals↗

PubMed1980

Effect of dietary lipids on growth, tissue composition and metabolism of the oyster (Crassostrea virginica).

Hatchery reared oysters (Crassostrea virginica) were fed six different diets for 30 weeks. The diets contained cod liver oil (CLO), corn oil (CO), corn oil and cod liver oil (1:2) (CO + CLO), hyrogenated coconut oil (HCO), ethyl esters of cod liver oil fatty acids (SF) or cod liver oil ethyl esters supplemented with cholesterol (CH). Data on growth and tissue composition imply that oysters have an essential fatty acid (EFA) requirement for both linolenic or omega 3 and linoleic or omega 6 series fatty acids, with the former playing a more significant role. The feeding study supported by a 14C-acetate metabolism experiment suggests that these oysters were unable to synthesize sterols and excessively high dietary sterol (1% of the dry weight of the diet) inhibited growth.

Animals↗

PubMed1976

Dietary lipid requirements of adult lobsters, Homarus americanus (M.E.).

The effects of several dietary lipids on adult American lobster (Homarus americanus) were assessed over a 10 month feeding period. Cod liver oil (CLO) resulted in greater precent weight gains, feed conversion, percent edible meat and higher serum protein and hemocyte counts than either corn oil (CO) or hydrogenated coconut oil (HCO). These differences were probably due to an essential fatty acid (EFA) requirement by the lobster for linolenic series omega3 or other fatty acids present in CLO. The linoleic or omega6 fatty acids of CO appeared to have some sparing effect on several of the EFA deficiency symptoms. It was found that 5% CLO was optimal for mean percent weight gain, molt incidence, feed conversion and hemocyte counts of lobsters. Further increases in dietary CLO to 10% and 15% resulted in no significant improvement of any of the condition indices used. There was a decrease in serum protein and calcium when lobsters were fed a non-saponifiable sterol deficient diet. The addition of 1% cholesterol to the diet raised the serum protein, but resulted in even a greater decrease in the serum calcium level.

Animals↗

PubMed1972