Scallop Muscle Research Articles

Expression characteristics and functional analysis of Krüppel-like factor 4 in adductor muscle and mantle of Zhikong scallop Chlamys farreri.

Krüppel-like factor 4 (KLF4) is an important transcription factor involving in formation and maintenance of muscles in mammals. However, no data are available on KLF4 function in shellfish muscles which play vital roles in the movement, stress response, and physiology in shellfish. In the present study, we revealed that the Klf4 mRNA of Zhikong scallop Chlamys farreri was expressed in most tissues, which has high level in adductor muscle, mantle, kidney, and testis. Positive signals of the Klf4 mRNA and protein were visible in all skeletal muscle fibers of adductor muscle, and all the cells of C. farreri mantle. Furthermore, the knockdown of Klf4 mRNA in adductor muscle and mantle by means of in vivo RNA interference led to some different phenotypes, including disordered arrangement of muscle fibers in adductor muscle and mantle, abnormal structures of skeletal muscles, and reduced muscle fibers under endepidermis of mantle. Our findings demonstrated that Klf4 plays important roles in maintenance of muscle functions in C. farreri adductor muscle and mantle, and suggested that its regulatory way in skeletal muscle may be different from the smooth muscle in shellfish.

Effect of ultrasound pretreatment on hot air drying rate of scallop muscles

To improve the drying rate and to reduce the energy consumption of aquatic product, scallop muscles were treated by ultrasonic with different frequency, time and different temperature. The hot air drying rate of treated scallop muscles was determined, and, meanwhile, several quality parameters such as the shrinkage and rehydration rate of samples with pretreatment were determined to compare with those of untreated samples. The results indicated that the drying rate of scallop muscles can be improved by the ultrasonic pretreatment without affecting the quality. Under a 70 kHz for 30min at 25°C, the drying rate of pretreatments is 1.29 times higher compared with that of the control group.

Draft genome and SNPs associated with carotenoid accumulation in adductor muscles of bay scallop (Argopecten irradians).

Carotenoids are commonly deposited in the gonads of marine bivalves but rarely in their adductor muscles. An orange-adductor variant was identified in our breeding program for the bay scallop Argopecten irradians. In the present study, bay scallop genome survey sequencing was conducted, followed by genotyping by sequencing (GBS)-based case-control association analysis in a selfing family that exhibited segregation in adductor color. K-mer analysis (K=17) revealed that the bay scallop genome is about 990 Mb in length. De novo assembly produced 217,310 scaffold sequences, which provided 72.1% coverage of the whole genome and covered 72,187 transcripts, thereby yielding the most informative sequence resource for bay scallop to date. The average carotenoid content of the orange-adductor progenies was significantly higher than that of the white-adductor progenies. Thus, 20 individuals of each subgroup were sampled for case-control analysis. As many as 15,224 heterozygous loci were identified in the parent, among which 9280 were genotyped in at least 10 individuals of each of the two sub-groups. Association analysis indicated that 126 SNPs were associated with carotenoid accumulation in the adductor muscle and that 88 of these were significantly enriched on 28 scaffolds (FDR controlled P < 0.05). The SNPs and genes located on these scaffolds can serve as valuable candidates for further research into the mechanisms by which marine bivalves accumulate carotenoids in their adductor muscles.

Antibrowning of the Adductor Muscles of Bay Scallop by Glutathione During Hot Air Drying

ABSTRACTBrowning in the adductor muscle of bay scallop (Argopecten irradians) tends to occur during hot air drying due to polyphenoloxidase (PPO) and Maillard reaction and decreases the sensory quality and commercial value of bay scallop adductor muscles (BSAM). In the present study, the effects of glutathione on the browning inhibition of BSAM were evaluated. The PPO activity in BSAM was inhibited by 97.8 with 0.08% glutathione. The browning of BSAM pretreated with glutathione was evaluated during hot air drying. Compared with the control, BSAM pretreated with glutathione resulted in less drying time and browning during hot air drying. The results indicate that pretreatment with glutathione may be a promising method of BSAM browning inhibition during hot air drying.

Association of myostatin variants with growth traits of Zhikong scallop (Chlamys farreri)

Scallop is a popular sea food and an important aquaculture shellfish. Identification of genes and genetic variants relating to scallop growth could benefit high-yielding scallop breeding. Myostatin (MSTN) is a conservative regulator of muscle growth, and has become one of the most important target genes for genetic improvement of the production of farmed animals. In this study, four single nucleotide polymorphisms (SNPs) were identified in the 5’ flanking region of MSTN gene (CfMSTN) in Zhikong scallop (Chlamys farreri). The association of these SNPs with scallop growth traits, including shell length, shell height, body weight and striated muscle weight was analyzed. The SNP g-1162G<T was found to associate with shell length, shell height, and striated muscle weight. The TT type scallops showed significantly higher trait values than those of GT type, and the GG type individuals exhibited median values. On the contrary, significantly more CfMSTN transcripts were detected in the striated muscle of GT type scallops than in those of TT and GG type ones. Our results suggested that CfMSTN might regulate the scallop muscle growth negatively, and SNP g-1162G<T can be used as a candidate marker for the selective breeding of high-yielding scallop.

Effects of temperature change on physiological and biochemical responses of Yesso scallop, Patinopecten yessoensis

Water temperature can be a significant environmental stressor that affects the physiological and biochemical responses of mollusks. Yesso scallop, Patinopecten yessoensis, is influenced by water temperature fluctuations caused by the Northern Yellow Sea Cold Water Mass. Here, the effects of acute seawater temperature change, gradual temperature change, and fluctuating temperature on the physiological and enzymatic activities in Yesso scallop were studied. Scallops were transferred directly from rearing temperature (15°C) to 5, 10, or 20°C for the acute water temperature change treatment. Scallops in the gradual water temperature change treatment were acclimated to different temperatures (5, 10, and 20°C) by increasing or decreasing seawater temperature progressively (1–2°C/day). The results showed that oxygen consumption and ammonia-N excretion rates in the 20°C-acute water temperature change treatment were significantly higher than those in the gradual treatment (one-way ANOVA, P<0.01). However, scallop ingestion rate decreased significantly in response to an acute water temperature decrease from 15 to 5°C, compared with equivalent groups exposed to a gradual temperature drop (one-way ANOVA, P<0.01). Moreover, hepatopancreatic superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), and lysozyme (LSZ) activities reached their highest levels in the 20°C-acute treatment after 12h. Malondialdehyde (MDA) content increased significantly following the acute water temperature changes and reached the highest level in 10°C-acute treatment after 72h. Heat shock protein70 gene (Hsp70) expression levels also increased significantly when water temperature was increased rapidly from 15 to 20°C or decreased rapidly from 15 to 10°C (P<0.01). In the fluctuation treatment, seawater temperature was altered every 12h for a total of six fluctuations. Scallops were transferred directly from 15 to 7°C (first fluctuation), moved from 7 to 15°C for the next 12h (second fluctuation), and then transferred from 15 to 7°C again (third fluctuation) and so on. As results, significant increases in SOD and CAT activities and MDA content, and decreases in ACP and LSZ activities were observed (one-way ANOVA, P<0.01). Significantly upregulated Hsp70 expression was also found in hemocytes, gills, and the adductor muscle of scallops in the fluctuating temperature treatment (one-way ANOVA, P<0.01). In conclusion, acute water temperature changes and fluctuations impacted the physiological and enzymatic activities of Yesso scallops and upregulated Hsp70 expression.

Technical Development of Processing of Boiled-dried Adductor Muscle of Scallop to Improve the Productivity and Quality of Manufacturing

Technical Development of Processing of Boiled-dried Adductor Muscle of Scallop to Improve the Productivity and Quality of Manufacturing

Study of the Effect of High-Pulsed Electric Field Pretreatment on Hot Air Drying Rate of Scallop Muscle

To improve the drying rate and to reduce the energy consumption of aquatic product, scallop muscle were treated with high pulse electric field (HPEF) in different frequency, and different voltage. The hot air drying rate of treated scallop muscle was determined, meanwhile, several quality parameters such as the shrinkage and rehydration rate of samples with pretreatment were determined to compare with those of untreated samples. The results indicated that the drying rate of scallop muscle can be improved by HPEF pretreatment without affecting the quality, and 22.5kV for pretreatment voltage and 50Hz for pretreatment frequency is the optimum treated parameters.

Agglutination activities of haemolymph and tissue extracts in scallop Chlamys farreri and purification of mannan-binding lectin from haemolymph

Agglutination plays a crucial role in eliminating potential pathogens in marine invertebrates. In this paper, cell-free haemolymph (CFH) and crude extracts from the haemocytes, gills, mantle, hepatopancreas, gonad, kidney and adductor muscle of scallop (Chlamys farreri) were obtained, and the agglutination activities of these extracts were tested separately against mouse blood cells (MBC) and fluorescein isothiocyanate-labelled microbes. Agglutination inhibition assays were carried out with EDTA and saccharides. Finally, a mannan-binding lectin (MBL, one of the main lectins in haemolymph) was purified from CFH by affinity chromatography using a mannan-sepharose column and analysed using native- and denaturing-PAGE. The results showed the CFH could aggregate Vibrio anguillarum, Staphylococcus aureus, Bacillus subtilis, Pichia pastoris and MBC, and the agglutination could be inhibited by DEAE dextran, EDTA, D-mannose-6-phosphate, N-acetyl glucosamine, mannan, zymosan A, chondroitin sulphate, peptidoglycan (PGN) and lipopolysaccharides (LPS); Gill extracts aggregated S. aureus, B. subtilis and P. pastoris, and the agglutination activity could be inhibited by EDTA, N-acetyl galactosamine, mannan, zymosan A, chondroitin sulphate, PGN and LPS; Mantle, hepatopancreas, gonad and kidney extracts could only aggregate B. subtilis, and this could be inhibited by mannan, zymosan A and PGN; however, no agglutination activity was detected using haemocyte or adductor muscle extracts. The results indicate that multiple types of lectins exist in C. farreri, and CFH has the highest agglutination activity. Purified MBL exhibited a molecular mass of 645kDa using native-PAGE and 73kDa using SDS-PAGE.

New Procedures to Improve Productivity and Quality in the Manufacture of Boiled-dried Adductor Muscles of Scallop (&lt;i&gt;shiraboshi&lt;/i&gt;)

ホタテガイの閉殻筋（貝柱）を，煮熱－乾燥させた白干しは北海道北部が主産地となっている。白干しの製造工程には様々な問題点があるが，主には貝の開殻，脱殻操作における生産低下や過度な褐変による製品の外観品質低下である。本研究では白干し製造の生産性を向上させる新しい操作と工程を開発した。第一に内在G6Pの産出が褐変に影響するという仮説をもとに，開殻脱殻工程後の生に近い貝柱を素早く加熱し失活させる新しい工程を導入した。この結果，失活工程で得られる熱水抽出液はグリシン，タウリンに富み高付加価値の副産物であった。第二に貝の外側から限定的に短時間飽和蒸気をあてる操作に開殻脱殻工程を改良した。この新しい操作によって従来の煮熟蒸煮中の固形分溶出に起因する貝柱歩留まりの低下やエキスの損失を改善した。2つの工程改良を含む新操作は白干しの生産性を改善すると共に新しい副産物を得るという結果を得た。

Quality of Weathervane Scallops (Patinope ctencaurinus) from Eastern and Western Gulf of Alaska

ABSTRACT Weathervane scallops (Patinopecten caurinus) have been harvested commercially in Alaska since 1967. From the beginning, vessel operators in the eastern Gulf of Alaska have reported poor scallop adductor muscle quality characterized by tissue of stringy texture that tears easily during shucking. The Alaska scallop industry designates these scallops as “weak meats” and has difficulty marketing the product. Our research objective was to quantify variability in the quality of adductor muscle of Alaskan weathervane scallops. Physical measurements and chemical composition analyses were conducted for 2 groups of whole scallops from Yakutat (weak and standard) and 2 groups of scallop adductor muscles from Kodiak (Kodiak 1 and Kodiak 2). Moisture content was significantly higher (P 0.05) for standard, Kodiak 1, and Kodiak 2 adductor muscles, but was significantly lower (P < 0.05) in weak adductor muscles. Muscle condition...

Molecular Characterization of TGF-β Type I Receptor Gene (Tgfbr1) in Chlamys farreri, and the Association of Allelic Variants with Growth Traits

BackgroundScallops are an economically important aquaculture species in Asian countries, and growth-rate improvement is one of the main focuses of scallop breeding. Investigating the genetic regulation of scallop growth could benefit scallop breeding, as such research is currently limited. The transforming growth factor beta (TGF-β) signaling through type I and type II receptors, plays critical roles in regulating cell proliferation and growth, and is thus a plausible candidate growth regulator in scallops.ResultsWe cloned and characterized the TGF-β type I receptor (Tgfbr1) gene from Zhikong scallops (Chlamys farreri). The deduced amino acid sequence contains characteristic residues and exhibits the conserved structure of Tgfbr1 proteins. A high expression level of scallop Tgfbr1 was detected during early embryonic stages, whereas Tgfbr1 expression was enriched in the gonad and striated muscle in adults. A single nucleotide polymorphism (SNP, c. 1815C>T) in the 3′ UTR was identified. Scallops with genotype TT had higher growth traits values than those with genotype CC or CT in a full-sib family, and significant differences were found between genotypes CC and TT for shell length, shell height, and striated muscle weight. An expression analysis detected significantly more Tgfbr1 transcripts in the striated muscle of scallops with genotype CC compared to those with genotype TT or CT. Further evaluation in a population also revealed higher striated muscle weight in scallops with genotype TT than those with the other two genotypes. The inverse correlation between striated muscle mass and Tgfbr1 expression is consistent with TGF-β signaling having a negative effect on cell growth.ConclusionThe scallop Tgfbr1 gene was cloned and characterized, and an SNP potentially associated with both scallop growth and Tgfbr1 expression was identified. Our results suggest the negative regulation of Tgfbr1 in scallop growth and provide a candidate marker for Zhikong scallop breeding.

63. Quick freezing process in shellfish: Total volatile basic nitrogen and algal biotoxins values in scallops frozen on board in Argentina

Freezing on-board has made it possible to expand commercial fishing to new species that were not widely utilized until the late 1970s. Shellfish are one of the commercial fishery products that can be harvested from natural beds located in far offshore ocean areas by factory trawler fleet where shellfish is processed and frozen quickly. In this way large volumes of frozen products can be obtained with optimal commercial quality and good sanitary conditions. In Argentina, scallop harvesting followed by on board quick freezing started in 1996. The aim of this presentation is to describe the quick freezing process applied by factory trawlers to scallops harvested from the Argentine Sea and to report the results obtained from the total volatile basic nitrogen (TVB-N) and biotoxin analysis of samples of these products. These data were collected at the National Animal Health and Agri-Food Quality Service (SENASA)-Regional Laboratory at Mar del Plata city, Argentina, and they cover a 14-year time span, from 1997 to 2011. Captured specimens were selected by size according to commercial criteria, and those smaller than 55 mm were returned to the sea within 5–10 min of capture. Scallops were water vapor-opened in order to separate the adductor muscle from the rest of the soft tissues (viscera, gonads and mantle). Adductor muscles enter a freezing tunnel where a fast flow of cold air induces a shock freezing of the tissue (at −26 °C/−30 °C), thus allowing to obtain in some 20 min individually quick frozen adductor muscle units. The time elapsed since scallops selected by size enter the processing line until the final commercial product is stored is about 30 min. This short processing time allows an optimal preservation of all organoleptic characteristics and at the same time prevents phytoplankton biotoxin diffusion from viscera (the primary storage region in the live animal) to muscle. TVB-N determinations were carried out by the Antonacopoulos method. The mean values recorded in the quick frozen scallop muscles ranged from 8.0 to 9.0 mg%. Measurements performed in muscle tissue from scallops stored in freezing chambers (−18 °C) gave TVB-N values between 12 mg% and 13 mg%, whereas TVB-N values in adductor muscles stored at 4 °C were above 30 mg%. Biotoxin determination was performed by the mouse bioassay (MBA) employing the AOAC 959.08 method for Paralytic Shellfish Poison (PSP) and the procedure described by Yasumoto et al. in 1986 for Diarrheic Shellfish Poison (DSP). None of the adductor muscle samples tested had detectable PSP or DSP levels. This was so even on occasions when high PSP concentrations were detected in whole scallop samples. Our results show that the quick freezing process on board Argentinian factory trawler ships are suitable for obtaining a commercial product that fully retains freshness parameters as well as the sanitary characteristics required for human consumption.

Control of d-octopine formation in scallop adductor muscle as revealed through thermodynamic studies of octopine dehydrogenase

Octopine dehydrogenase (OcDH) from the adductor muscle of the great scallop, Pecten maximus (Linné, 1758), catalyses the NADH-dependent condensation of l-arginine and pyruvate to d-octopine, NAD(+) and water during escape swimming and subsequent recovery. During exercise, ATP is mainly provided by the transphosphorylation of phospho-l-arginine and to some extent by anaerobic glycolysis. NADH resulting from the glycolytic oxidation of 3-phosphoglyceraldehyde to 1,3-bisphosphoglycerate is reoxidized during d-octopine formation. In some scallops d-octopine starts to accumulate during prolonged, strong muscular work, whereas in other species d-octopine formation commences towards the end of swimming and continues to rise during subsequent recovery. The activity of OcDH is regulated by a mandatory, consecutive mode of substrate binding in the order NADH, l-arginine and pyruvate, as demonstrated by isothermal titration calorimetry. The first regulatory step in the forward reaction comprises the binding of NADH to OcDH with a dissociation constant K(d) of 0.014±0.006 mmol l(-1), which reflects a high affinity and tight association of the apoenzyme with the co-substrate. In the reverse direction, NAD(+) binds first with a K(d) of 0.20±0.004 mmol l(-1) followed by d-octopine. The binary OcDH-NADH complex associates with l-arginine with a K(d) of 5.5±0.05 mmol l(-1). Only this ternary complex combines with pyruvate, with an estimated K(d) of approximately 0.8 mmol l(-1) as deduced from pyruvate concentrations determined in the muscle of exhausted scallops. At tissue concentrations of pyruvate between 0.5 and 1.2 mmol l(-1) in the valve adductor muscle of fatigued P. maximus, binding of pyruvate to OcDH plays the most decisive role in initiating OcDH activity and, therefore, in controlling the onset of d-octopine formation.

Molecular cloning and characterization of the myostatin gene in a cultivated variety of bay scallop, Argopecten irradians

In this study, we cloned and characterized the myostatin (MSTN) gene from a cultivated strain of bay scallop, Argopecten irradians, “Zhongkehong”, and named it as the Ai-MSTN gene. The Ai-MSTN cDNA sequence was 3553bp, contained three exons with 1380bp in the open reading frame encoding 459 amino acids, and was 2014bp longer than one previously reported. Analysis of its genomic structure and expression profiles indicated that the sequence of MSTN was 12473bp (Genbank: JN684902) containing 3 exons and 2 introns, which was conserved with its vertebrate and invertebrate homologs. In silico analysis revealed that the promoter region of Ai-MSTN contained several muscle specific regulatory elements. The 3D structure of Ai-MSTN was similar to that of the known mouse MSTN. Ai-MSTN was expressed not only in the digestive gland, pericardium, gill, adductor muscle, gonad and mantle of the bay scallop, but also in its hemolymph, which was firstly reported in mollusks. These findings provide genomic and protein information and expression profiles of the Ai-MSTN gene and lay the groundwork for further investigations of its functional significance in this economically important sea food, bay scallops.

Physical and Sensory Properties of Electrohydrodynamic (EHD) Dried Scallop Muscle

Electrohydrodynamic (EHD) drying was tested as an improved dehydration method for scallop muscle. The scallop muscle was dried in an EHD drying system at 15°C, in an oven at 60°C, and in ambient air at 15°C. The energy consumption of EHD and oven drying, as well as the shrinkage rate, water absorption, solid loss, and sensory properties such as color and anti-crushing durability of the dried scallop muscle were measured. Results showed that the drying rate of scallop muscle significantly improved using the EHD drying system. Under a 45 kV voltage, the drying rate of EHD is 7 times higher compared with that of air drying in the 1st h. Compared with oven drying, EHD drying was more efficient in terms of energy saving. Furthermore, EHD drying cost only 28.67% of the electric energy required for oven drying. The dried scallop muscle by EHD had better sensory qualities and higher anti-crushing durability. EHD drying is very advantageous and can be used as a substitute to the traditional drying method.

Instability of the S1/S2 Hinge is not Affected by the Myosin Filament

The S1/S2 hinge of myosin is thought to be unstable in some species of myosin such as myosin VI and certain scallop muscle myosin. To examine the stability of the S1/S2 hinge of rabbit skeletal muscle myosin, gravitational force spectrometry was used to measure the separation of myosin heads bound in rigor to actin immobilized on glass microspheres. The molecular lengths of this separation were measured at different levels of applied force up to the limit that the rigor bond would sustain of about 10 pN in these experiments. The molecular lengths were found to increase linearly with the applied force up to lengths exceeding 100 nm which requires a partial unraveling of the S2 coiled coil in the single myosin molecule. Free-fall force spectrometry on such single myosin molecules confirmed that the coiled coil could reversibly unravel and refold at forces less than 13 pN. In order to test whether thick filament formation would affect this instability under force, synthetic cofilaments of proteolytically isolated myosin rod and intact myosin were prepared at different ratios of myosin to rod up to ratios where it is expected that only one intact myosin would be present per myosin rod cofilament. The force-distance relationships for myosin in the cofilament were not substantially different from those of single myosin molecules. These data indicate the possibility that vertebrate skeletal muscle myosin may also utilize S1/S2 hinge unraveling to provide flexibility during crossbridge formation so that a productive binding orientation is achieved. The reversibility of the unraveling of the coiled coil might contribute to the mechanism of motility under some circumstances as has been proposed for non-muscle myosin VI.

Biochemical change of fermented scallop (Argopecten irradians Lamarck) flour paste in different fermentation periods

The aim of this paper was to study the biochemical changes in fermented scallop flour paste (SFP) during different fermentation periods. SFP was prepared with scallop muscles, flour koji, salt, rice koji, and neutral protease at 40°C for 12 days. Biochemical changes during fermentation were investigated. By reducing sugar content, formaldehyde nitrogen content, total acid content, and free amino acids (FAAs), the concentration of SFP was increased but water activity was decreased. Most FAAs were increased, and the amounts of glutamic acid, glycine, alanine, and leucine were high. Some amino acid concentrations were higher than their taste threshold, such as the glutamate of umami, the glycine and alanine of sweet and umami, and the arginine and lysine of bitter and sweet. They contributed significantly to the characteristic taste of SFP. Therefore, SFP is a potential seasoning agent with nutritional properties and good taste.

Exploring Natural Products for New Taste Sensations

This paper discusses the discovery of uncommon taste or trigeminal active compounds and their associated sensory analysis using human tasting panels with the aim of enhancing the overall taste experience whilst reducing where possible the sugar and salt content of foods. The first example outlines the discovery of the sensory quality attributes of (R)-2-(carboxymethylamino)propanoic acid, named (R)-strombine, as assessed by a panel of 47 subjects to confirm its contribution to the typical taste of scallop muscle. The second example discusses the pungency and trigeminal effect of polygodial, which is compared with piperine and capsaicin, as well as the elucidation of a new structure eliciting a trigeminal effect, (+/-)-trans-2,3,3a,7a-tetrahydro-1 H-indene-4-carbaldehyde, discovered in Amomum tsao-ko. Finally, the time intensity trigeminal effect of (-)-menthol is compared with (1R,2RS,4RS)-1-isopropyl-4-methylbicyclo[3.1.0]hexan-2-ol, named dihydroumbellulol, a new cooling compound obtained by hemi-synthesis from umbellulone extracted from Umbellularia californica Nutt.

Diet and performance in the scallop,Argopecten purpuratus: force production during escape responses and mitochondrial oxidative capacities

We examined whether escape response performance and mitochondrial capacities could reveal differences created by feeding scallops, Argopecten purpuratus, mono-specific algal diets composed of either Chaetoceros calcitrans or Isochrysis galbana (variety T. iso) hereafter T. iso. Before and after feeding scallops with these diets, we assessed force production in vivo to evaluate escape response performance (initial and repeat). We measured oxidative capacities of mitochondria isolated from the adductor muscle and from the male and female portions of the gonad. Initial escape response performance was reduced more by the C. calcitrans diet than by the T. iso diet. Repeat escape responses, which require aerobic recuperation, were reduced by both treatments. The oxidative capacity of mitochondria isolated from muscle and female gonad was markedly lower in scallops fed C. calcitrans than in those fed T. iso. Flux through complex I–IV and through complex IV was also lower in mitochondria from muscle of scallops fed C. calcitrans than in those fed T. iso. Muscle aerobic capacity, assessed by citrate synthase activity, was lower in scallops fed C. calcitrans than in those fed T. iso. Despite the marked differences in fatty acid (FA) composition of the algal diets, the FA composition of mitochondrial phospholipids differed little between scallops fed C. calcitrans and those fed T. iso. Both escape response behaviour and mitochondrial capacities changed with feeding mono-specific diets. The simplicity of measurements of scallop escape responses suggests this as a practical means of evaluating the status of scallops for the two monoalgal diets tested.