John Donlon

Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino. III. response of abalone to various levels of dietary lipid

This study was carried out to evaluate the effects of graded dietary lipid levels on the survival, growth and body composition of Haliotis tuberculata and H. discus hannai. Six purified diets were formulated to provide approximately 25% protein, and a series of graded lipid levels, from 0.63 to 11.58%, in the form of a mixture of corn oil and menhaden fish oil (1:1). The red alga, Palmaria palmata, was used as a control diet. Abalone juveniles of similar size (H. tuberculata, 588 mg; H. discus hannai, 389 mg) were distributed in a recirculating system using a completely randomized design with 7 treatments and 3 replicates per treatment (20 juveniles/replicate), and fed the appropriate diet every 3rd day for a 100-day period. P. palmata produced similar or better growth performance for both abalone species than the artificial diets. Among the artificial diets, significantly higher weight gains were observed for H. discus hannai at dietary lipid levels ranging from 3.11 to 7.09%, and for H. tuberculata at 3.11%. However, growth in terms of protein gain was best when both species of abalone were fed 3.11 and 5.15% dietary lipid. Soft-body lipid content positively correlated with dietary lipid levels. Inversely, soft-body protein concentrations decreased with the increase of dietary lipid. Overall, H. discus hannai deposited a slightly higher level of lipid, but a lower level of protein than H. tuberculata. There were no significant differences in survival of abalone fed the experimental diets.

Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata Linnaeus and Haliotis discus hannai Ino. I: Effects of algal diets on growth and biochemical composition

Summary This study was conducted to examine the nutritional value of eight algal diets for two species of abalone, Haliotis tuberculata and Haliotis discus hannai, by measuring biochemical composition of the algae and relating this to feeding rate, growth and biochemical composition of the animals. Nutritional value of algal diets can be divided into three categories for each species of abalone. For H. tuberculata the best performance was on the mixed diet and Palmaria palmata intermediate was Alaria esculenta, Ulva lactuca and Laminaria digitata, and lowest growth was on Laminaria saccharina and Chondrus crispus. For H. discus hannai, best performance was on A. esculenta, P. palmata and the mixed diet; intermediate was on L. saccharina and L. digitata and lowest was on U. lactuca. It is generally accepted that high “balanced” levels of protein (>15%), lipid (3–5%) and carbohydrate (20–30%), with no detrimental substances in natural algae are essential for optimal growth performance of these abalone. The ...

Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino. V. The role of polyunsaturated fatty acids of macroalgae in abalone nutrition

Abstract This study was undertaken to evaluate the nutritional role of polyunsaturated fatty acids (PUFA) in dietary macroalgae for the abalone, Haliotis tuberculata and Haliotis discus hannai . The effects of five species of macroalgae ( Alarla esculenta, Laminaria digitata, Laminaria saccharina, Palmaria palmata and Ulva lactuca ) on specific growth rates (SGR) of the abalone and, the relationship between abalone SGR and fatty acid profiles in the algae were investigated. The current study confirmed our previous findings. Based on SGR the dietary values of these macroalgae can be listed in a decreasing order as follows: P. palmata A. esculenta U. lactuca L. digitata and L. saccharina for H. tuberculata and, A. esculenta P. palmata L. digitata, L: saccharina and U. lactuca for H. discus hannai . Fatty acid analysis revealed that C 18 and C 20 PUFA, such as 18:4n − 3, 18:3n − 3, 20:4n − 6 and 20:5n − 3, were dominant in the brown algae, A. esculenta L. digitata and L. saccharina . The red alga, P. palmata , was characterised by the highest proportion of 20:5n − 3 among the selected algae. In the green alga, U. lactuca , however, the dominant PUFA were C 16 and C 18 fatty acids, while C 20 fatty acids were minimal. All the selected algae consistently contained very low levels of C 22 fatty acids. Statistical analyses demonstrated that (a) 20:5n − 3 played a prominent role in the nutrition of both abalone species; (b) 18:3n − 3 as well as other n − 3 PUFA, and 18:2n − 6 together with other n − 3,6 long-chained PUFA also contributed to the faster growth of H. tuberculata and H. discus hannai , respectively. The results suggest that the PUFA of both n − 3 and n − 6 families seem to be essential for growth of H. discus hannai ; for H. tuberculata , however, growth enhancement appeared to depend largely on n − 3 PUFA.

Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino: II. Amino acid composition of abalone and six species of macroalgae with an assessment of their nutritional value

Abstract This study was conducted to evaluate the nutritional value of protein in natural feeds for the two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino. The amino acid compositions of 6 species of macroalgae (Ulva lactuca, Chondrus crispus, Palmaria palmata, Alaria esculenta, Laminaria digitata and Laminaria saccharina) and of the whole soft body of these abalone were determined and compared. The effects of these algal diets on the free amino acid (FAA) profiles in the viscera and muscle of animals were investigated. To find a suitable index to evaluate the protein quality of natural diets for algivores, several indices were computed and correlated to the growth performance of abalone using correlation analysis. These two species of abalone have a very similar amino acid composition, indicating that they may have similar amino acid requirements. In all the selected algae, arginine may be the limiting amino acid, and in some instances methionine, threonine or histidine may be also limiting. Judging from the results of feeding test and amino acid analysis, P. palmata and A. esculenta seem to have the better amino acid pattern and availability among the selected algae. On the other hand, U. lactuca and C. crispus appear to be poor in their amino acid availability and/or pattern. Dietary treatments significantly affected the FAA profiles in animal tissues. The essential amino acid index (EAAI) and the degree of similarity (DS) of EAA patterns may not be applicable to evaluating the nutritional value of protein in natural feeds for the algivorous molluscs. Among the indices examined, the newly proposed index—balance and adequacy of free EAA in viscera (BAEAAv)—seems to be suitable for estimation of protein quality of natural feeds for abalone, because it takes into account the balance, adequacy and availability of EAA in natural diets.

A cytotoxicity assay for the detection and differentiation of two families of shellfish toxins

There is an urgent need for an alternative to the mouse bioassay for the detection of algal toxins in shellfish on both analytical and animal welfare grounds. Several alternative methodologies have been described, but have not gained widespread acceptance to date, because each assay measures only one or a small number of related phycotoxins out of the increasing range that needs to be detected. A simple cytotoxicity assay using either the HepG2 or ECV-304 cell lines is described with two end-point measurements, which can detect and distinguish between two unrelated classes of phycotoxins. Morphological examination following 3h exposure to the sample enables the detection of the diarrhetic shellfish poisons, including okadaic acid and related toxins. Viability testing using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide), following 24h exposure of the same cells to the sample, reveals a second class of toxin, which is most probably the newly-described toxin, azaspiracid. This assay should play an important role in shellfish monitoring in the future.

Genetic variation at three polymorphic loci in wild and hatchery stocks of the abalone, Haliotis tuberculata Linnaeus

Abstract The abalone, Haliotis tuberculata, is a gastropod mollusc of commercial importance in Europe with considerable potential for aquaculture. A wild population of H. tuberculata from Guernsey, Channel Islands was compared to two hatchery populations; one an F1 stock produced by a hatchery in Guernsey, the other an F3 stock cultured at the Shellfish Research Laboratory (SRL) at Carna, Ireland. The F1 and SRL stocks were each derived from the Guernsey wild population and reproductively isolated from this population for one and three generations, respectively. The three populations were screened for allozyme variation at three polymorphic loci, Gpi, Pgm and Mdh, using starch-gel electrophoresis. When compared with the wild population, both the F1 and SRL samples were very similar in terms of mean effective number of alleles per locus and levels of heterozygosity. However, the SRL stock did show a reduced number of rare alleles when compared to the F1 and Guernsey samples but without showing any evidence of inbreeding or reduction in levels of heterozygosity. Effective population size was calculated from direct census (Ne) and temporal changes in allelic frequencies ( N k ). Ne was estimated to be 48 and 54.5 for SRL and F1, respectively, whereas calculated N k was 21.4 and 23.9, respectively.

Fate of oxytetracycline in a fresh water fish farm : influence of effluent treatment systems

Abstract The fate of orally administered oxytetracycline in a fresh-water hatchery was investigated using high-performance liquid chromatography. A filter of nominal porosity 50 μm in the farm effluent was capable of at least a 500–650-fold concentration of the oxytetracycline into the filter retentate flow. No oxytetracycline was detected in the filtered farm effluent (limit of detection 0.02 μg·ml−1). Analysis of hourly samples of the retentate taken over a 24-hour period allowed an estimate of the daily amount of oxytetracycline retained by the filter. This estimate (1250 g) was of the same order as the amount of oxytetracycline used on the farm (904 g on the day of sampling and 1104 g on the preceding day). Thus the quasi-totality of the input oxytetracycline was removed from the farm effluent by the filter. A sedimentation trap on the filter retentate flow removed oxytetracycline from this flow at a variable and lower (12–92%) efficiency. It is argued that correct design of effluent treatment systems could significantly reduce the environmental impact of land-based fish farms.

Modification of the multiple forms of rat hepatic phenylalanine hydroxylase by in vitro phosphorylation

Abstract The two major forms of rat liver phenylalanine hydroxylase have been isolated and partially purified. The tetrahydrobiopterin-dependent activity of these forms can be differentially stimulated by exposure to enzymatic phosphorylating conditions. This in vitro treatment is associated with incorporation of 32p into the enzymes and generates a further, chromatographically distinct, species. These results suggest that the multiple forms of rat liver phenylalanine hydroxylase are due to different degrees of phosphorylation.

Modulations of rat hepatic phenylalanine hydroxylase due to induced diabetes or high-protein diet

Abstract The tetrahydrobiopterin-dependent activity and apparent state of phosphorylation of rat hepatic phenylalanine hydroxylase is stimulated three days after induction of diabetes by the administration of streptozotocin. This response can be inhibited by concurrent treatment with insulin. Animals that are subjected to the diabetic state for five to seven days show an apparent increase in the amount of hydroxylase present. In addition, rats fed on a high-protein diet for one week have elevated tetrahydrobiopterin-dependent hydroxylase activity and an altered distribution of the multiple forms of this enzyme. These observations support the conclusion that rat hepatic phenylalanine hydroxylase can be modulated in vivo both by transient and sustained mechanisms that are responsive to an altered physiological status.

CORRELATION OF RAT HEPATIC PHENYLALANINE HYDROXYLASE, WITH TETRAHYDROBIOPTERIN AND GTP CONCENTRATIONS

Hepatic phenylalanine hydroxylase is reported to be more abundant in experimentally-diabetic rats; whereas livers of animals fed a high protein diet, where gluconeogenesis also prevails, have normal amounts of this enzyme. In this study, in addition to seeking an explanation for this effect of experimental diabetes, we also examined the effects of providing alternative dietary gluconeogenic substrates. In rats fed a diet composed of 40% (w/w) glycerol, the specific activities of hepatic phenylalanine hydroxylase are decreased to about 60% of control values. There is no effect on the apparent state of phosphorylation of the enzyme. However, studies on the incorporation of radiolabelled leucine into liver phenylalanine hydroxylase suggested that there was a decreased rate of synthesis. Similarly, animals fed a diet containing 85% (w/w) fructose also have diminished phenylalanine hydroxylase activities. Under all of the above circumstances and also in streptozotocin-induced diabetic animals, alterations in the concentrations of the hydroxylase cofactor, tetrahydrobiopterin and of GTP closely correlate with the effects on the enzyme activities. They are elevated in livers of diabetic animals and significantly diminished in livers of rats fed diets rich in glycerol or fructose. These observations suggest that in adult rat both liver tetrahydrobiopterin concentrations and the expression of hepatic phenylalanine hydroxylase are regulated by GTP [210].