Predicting glycogen concentration in the foot muscle of abalone using near infrared reflectance spectroscopy (NIRS).

Near infrared reflectance spectroscopy (NIRS) was used to predict glycogen concentrations in the foot muscle of cultured abalone. NIR spectra of live, shucked and freeze-dried abalones were modelled against chemically measured glycogen data (range: 0.77-40.9% of dry weight (DW)) using partial least squares (PLS) regression. The calibration models were then used to predict glycogen concentrations of test abalone samples and model robustness was assessed from coefficient of determination of the validation (R2(val)) and standard error of prediction (SEP) values. The model for freeze-dried abalone gave the best prediction (R2(val) 0.97, SEP=1.71), making it suitable for quantifying glycogen. Models for live and shucked abalones had R2(val) of 0.86 and 0.90, and SEP of 3.46 and 3.07 respectively, making them suitable for producing estimations of glycogen concentration. As glycogen is a taste-active component associated with palatability in abalone, this study demonstrated the potential of NIRS as a rapid method to monitor the factors associated with abalone quality.

Cryptophyceae and rhodophyceae; chemotaxonomy, phylogeny, and application.

The biochemical compositions of seven strains of marine cryptomonad and a rhodophyte were determined in logarithmic phase batch (1.4 L flask) and semi-continuous (10 L carboy) culture. Lipid ranged from 13% to 28%, protein ranged from 53% to 68%, and carbohydrate ranged from 9% to 24% of the organic weight. The major lipid classes in the species examined were polar lipids (78-88% of total lipid). The major sterol in the Cryptophyceae and the Rhodophyceae was 24-methylcholesta-5,22E-dien-3beta-ol (62-99% of total sterols); which is also the major sterol in some diatoms and haptophytes. Smaller proportions of cholest-5-en-3beta-ol (1-17.7%) were also found in the Cryptophyceae. Most cryptomonads contained high proportions of the n-3 polyunsaturated fatty acids (PUFA), 18:3n-3 (20.7-29.9% of the total fatty acids), 18:4n-3 (12.5-30.2%), 20:5n-3 (7.6-13.2%) and 22:6n-3 (6.4-10.8%). However, the blue-green cryptomonad Chroomonas placoidea was characterized by a low proportion of 22:6n-3 (0.2% of total fatty acids), and a significant proportion of 22:5n-6 (4.5%), and the presence of 24-ethylcholesta-5,22E-dien-3beta-ol (35.5% of total sterols). The fatty acid composition of the rhodophyte Rhodosorus sp. was similar to those of the Cryptophyceae except for lower proportions of 18:4n-3 and lack of C21 and C22 PUFA. It is postulated that the primary endosymbiosis of a photosynthetic n-3 C18 PUFA-producing prokaryote and a eukaryotic host capable of chain elongation and desaturation of exogenous PUFA, resulted in the Rhodophyceae capable of producing n-3 C20 PUFA. The secondary endosymbiosis of a photosynthetic n-3 C20 PUFA-producing eukaryote (such as a Rhodosorus sp. like-rhodophyte) and a eukaryotic host capable of further chain elongation and desaturation, resulted in the Cryptophyceae being capable of producing n-3 C20 and C22 PUFA de novo. Selected isolates were examined further in feeding trials with juvenile Pacific oysters (Crassostrea gigas). Rhodomonas salina CS-24(containing elevated 22:6n-3) produced high growth rates in oysters; equivalent to the microalga commonly used in aquaculture, Isochrysis sp. (T.ISO).

Biochemical composition during growth and starvation of early larval stages of cultured spiny lobster (Jasus edwardsii) phyllosoma.

We examined biochemical changes accompanying feeding and starvation from hatch to Stage VI (day 74 after hatch) in spiny lobster, Jasus edwardsii, phyllosoma larvae. Larval dry weights (dw) increased 17-fold from hatch (80+/-1 microg) to Stage VI (1415+/-44 microg). Larvae starved for 6-11 days at Stages II, IV and VI were 14-40% lighter than their fed counterparts fed enriched Artemia. The increases and losses in total dry weight during feeding and starvation were associated with changes in the content of protein (constituting 31.4-41.7% of dw) and carbohydrate (constituting 2.6-5.3% of dw), while larger changes in lipid content indicated its greater importance as an energy substrate. Lipid content increased from 7.9% of dw at hatch to its highest of 12.5% at Stage IV, but declined by 50% or more during starvation. This suggests that protein, carbohydrate and lipid are all important energy stores, although lipids are catabolized at a greater rate during food deprivation. The principal lipid class was polar lipid (PL; 79-92% of total lipid), followed by sterol (ST; 6-20%), with triacylglycerol and other lipid classes at <2%. PL were catabolized and ST were conserved during starvation. Changes in the fatty acid (FA) profile had mostly occurred before the first moult at day 8 after hatch, with gradual changes thereafter to Stage VI, reflecting their abundance in the Artemia diet. There was some conservation of the major essential FAs, 20:4n-6, 20:5n-3, 22:6n-3, and the FA profile showed large gains in the C(18) polyunsaturated FA, 18:1n-9, 18:2n-6. Ascorbic acid content increased 10-fold from hatch to the end of Stage I (36 and 333 microgg(-1) dw, respectively), while the content at the end of Stage II was higher in fed than that in starved larvae (439 and 174 microgg(-1) dw, respectively). Our study will assist in the development of alternatives to nutritionally incomplete diets, such as live ongrown Artemia, to meet the requirements of phyllosoma in culture.