Adductor Muscle Tissue Research Articles

In vitro transformation of paralytic shellfish toxins in the clams Mya arenaria and Protothaca staminea

Dissected tissues of two clam species, the Pacific littleneck, Protothaca staminea , and soft-shell, Mya arenaria , were evaluated for in vitro conversion of paralytic shellfish poisoning (PSP) toxins. Tissue homogenates were incubated with purified PSP toxins to determine the time-course of toxin conversion. The effects of boiling and addition of a natural reductant (glutathione) on toxin conversion were also assessed. For P. staminea , the digestive gland showed the greatest capacity for biotransformation, followed by gill, but mantle, adductor muscle, and siphon tissues exhibited very low conversion. In this species, the production of decarbamoyl derivatives was much greater from low potency N -sulfocarbamoyl toxins than from carbamate analogues. Decarbamolyation exhibited apparent specificity for α-epimers of all toxin substrates and this reaction was inhibited by boiling. Glutathione-mediated desulfation was tissue specific and had apparent specificity for β-epimers. These observations on P. staminea suggest that the above reactions are enzyme-mediated. In contrast, there was little toxin conversion in M. arenaria homogenates, but even this low activity was heat-labile and thus likely enzyme-mediated.

Susceptibility of juvenile Crassostrea gigas and resistance of Panope abrupta to Mikrocytos mackini

Samples from the field and laboratory exposure to Mikrocytos mackini (a tiny protistan parasite of unknown taxonomic affiliation) confirmed that juvenile Pacific oysters ( Crassostrea gigas) are susceptible to infection and the resulting disease. In the laboratory bath exposure experiment, a prevalence of infection approaching 100% and mortalities were observed in the small oysters (about 18 mm in shell length). However, in the same laboratory exposure experiment, similar aged geoduck clams ( Panope abrupta, about 8 mm in shell length) were resistant to infection. The main route of infection in the oysters appeared to be via the digestive tract and possibly the gills where the parasite multiplied within host cells. Other tissues such as the adductor muscle and vesicular connective tissue were subsequently colonized. Although the infection resulted in the mortality of some oysters, others appeared to overcome the disease.

Dimethylsulfoniopropionate in six species of giant clams and the evolution of dimethylsulfide after death

Substantial accumulation of dimethylsulfoniopropionate (DMSP) is documented in tissues of all six of the common species of giant clams (Tridacnidae). Results include measures of DMSP concentrations in siphonal mantle, byssal mantle, adductor muscle, and gill tissues obtained by gas chromatography of alkalized extracts plus evidence of DMSP from mass spectrometry. Formation of dimethylsulfide (DMS) by tissues after death is documented. The tridacnid clams maintain symbiotic associations with populations of dinoflagellates, which live within the enlarged siphonal mantle. We postulated that because of their association with dinoflagellates, the clams would chronically accumulate DMSP to high concentrations. Our results show that DMSP occurs at over 30 mmol·kg–1 in many tissues of tridacnid clams (sometimes 50–60 mmol·kg–1), meaning that these clams accumulate DMSP to the highest documented tissue concentrations in the animal kingdom. DMSP at such concentrations could affect multiple properties and functions. Our particular interest for this research was to assess whether postmortem breakdown of DMSP is responsible for the rapid development of potent off-odors and off-tastes that have blocked the commercial success of giant clam aquaculture. High concentrations of DMS produced in the day after death probably account for the peculiar perishability of giant clam tissues.

Influence of salinity on the physiological conditions in mussels, Perna perna and Perna viridis (Bivalvia: Mytilidae).

Perna genus was introduced to Venezuela, but nowadays, Perna perna and Perna viridis coexist and are commercially exploited from their natural beds. The aim of this work was to determine the effect of salinity on the physiological conditions of these species by studying RNA/DNA and Protein/DNA ratios. The organisms were collected from natural beds at La Esmeralda, Sucre State, Venezuela, and acclimatized for 15 days under laboratory conditions at 25 degrees C, 36 per thousand salinity, pH between 7 and 8 and more than 90% of oxygen saturation. Later, they were divided in two groups: for one group, the salinity concentration was increased (36 to 45 per thousand), and for the other, the salinity was decreased (36 to 15 per thousand). The rate of change was 1 per thousand every day. Ten organisms per group of both species were taken at each of 15, 20, 25, 30, 36, 40 y 45 per thousand salinity concentrations. Protein (colorimetric method) and nucleic acids (RNA and DNA by fluorometric method) concentrations were measured in the digestive gland, gills and adductor muscle tissues. Results indicate that P. perna can physiologically compensate the increase in salinity, but not when the salinity decreased, when proteins are the most needed macromolecules. The Protein/DNA index is directly related to salinity changes in both cases. P. viridis shows physiological compensation to salinity increases and decreases. The RNA/DNA index value in both cases supports this. Digestive gland and muscle tissues are the regulating tissues in both species. These results show that P. viridis has a higher degree of adaptability to salinity changes and, therefore, a greater potential for aquaculture than P. perna.

Ultrastructure of the mushroom body: digestion during metamorphosis of Utterbackia imbecillis (Bivalvia: Unionidae)

Abstract. Larvae of the freshwater mussel Utterbackia imbecillis metamorphose to juveniles either during their attachment to a host fish, or in vitro in a culture medium. This transformation includes degeneration of larval structures and development of the juvenile morphology. Early in metamorphosis the cells comprising the larval mantle enlarge and project into the mantle cavity, forming a structure referred to as the mushroom body. Its cells, which are ultrastructurally very similar to digestive cells of adult bivalves, are involved in pinocytosis or phagocytosis of the larval adductor muscle and of tissue from the host fish that is enclosed between the larval shells. Ingested material is passed from pinosomes to heterophagosomes which in turn fuse with heterolysosomes, where final degradation of ingested material occurs. Acid phosphatase activity was detected in heterophagosomes and heterolysosomes of all animals examined. In larvae that metamorphosed in vitro, the apical cytoplasm of the cells of the mushroom body, and the extracellular spaces among them, also exhibited acid phosphatase activity. Larvae reared on a host fish accumulated substantial deposits of lipids and glycogen within larval mantle cells during metamorphosis, whereas larvae reared in vitro did not. The larval mantle cells which constitute the mushroom body appear to be the primary sites of intracellular digestion of the larval adductor muscle and host tissue during metamorphosis.

Assessment of the state of the Japanese scallopMizuhopecten yessoensis in Alekseeva Bight (Peter the Great Bay, Sea of Japan) based on morphological and biochemical parameters

The results of an integrated examination of the state of the scallopMizuhopecten yessoensis in Alekseeva Bight (Peter the Great Bay, Sea of Japan) are presented. In mollusks of different ages, shell height was measured; in animals of commercial size (over 100 mm), some size and weight characteristics (annual increment of shell and adductor muscle and soft tissue weight) were determined. The morphology of the digestive gland and gills was studied. In the adductor muscle and digestive gland, the concentration of heavy metals (HMs) (Hg, Cu, Zn, Mn, Pb, Cd, Ni, Co, and Cr) was determined. In the digestive gland, metallothionein and reduced glutathione concentration was also determined, as was the activity of glutathione-dependent enzymes (glutathione peroxidase and glutathione reductase). In scallops collected outside Alekseeva Bight, the linear growth rate and adductor muscle weight were on average 1.3 and 1.7 times greater, respectively, than in those collected in the bight. In scallop organs, numerous histomorphological alterations were revealed: digestive cell vacuolization and hemocyte infiltration of the digestive gland, hyperplasia and vacuolization of the respiratory epithelium, and connective tissue hypertrophy in gill filaments. The biochemical parameters of scallops from Alekseeva Bight differed substantially from those of mollusks collected outside the bight. We conclude that one of the factors negatively affecting the state of theM. yessoensis population in Alekseeva Bight is the contamination of the bight with HMs, especially mercury. This is consistent with the results of chemical analysis of bottom sediments and tissues of two mytilid species,Modiolus kurilensis andCrenomytilus grayanus, specimens of which were collected in the bight together with the scallops [3].

The effect of PCBs on glycogen reserves in the eastern oyster Crassostrea virginica

Recent declines in Chesapeake Bay oyster populations have been attributed to disease, and reduced water quality from pollution. The stress associated with pollutant exposure may reduce energy available for growth and reproduction. Polychlorinated biphenyls (PCBs) are lipophilic contaminants that may potentially affect mobilization of lipid reserves, increasing reliance on glycogen stores, which could otherwise be utilized to supply energy for gametogenesis. Thus, PCBs may indirectly affect glycogen stores in oysters in a deleterious manner. To test for this effect, reproductively inactive oysters were exposed to PCBs by feeding individuals 0.7 g of algal paste containing 0, 0.35, or 3.5 μg PCBs daily for 8 weeks. Additionally, a group of oysters was exposed to PCBs (0, 0.35, and 3.5 μg) plus 0.3 g of non-toxic artificial sediment to examine interactive effects of sediment particles and PCBs. Adductor muscle, mantle, and gonadal tissues were analyzed for glycogen content. Results suggest that glycogen content is reduced in the adductor muscle with increasing PCB exposure, but there are no effects of PCBs in the mantle and gonadal tissues.

Distribution of Norwalk Virus within Shellfish Following Bioaccumulation and Subsequent Depuration by Detection Using RT-PCR

Consumption of raw bivalve mollusks contaminated with pathogens from human feces continues to present a human health risk. The purpose of this study was to monitor the uptake, localization, and removal of Norwalk virus (NV) in shellfish (oyster and clam) tissues by analyzing virus distribution in selected dissected tissues. Live shellfish were allowed to bioaccumulate different input titers of NV for time periods from 4 to 24 h. In some experiments, depuration by shellfish that bioaccumulated NV and Escherichia coli bacteria was allowed to proceed for 24 or 48 hours. Dissected stomach (St), digestive diverticula (DD), adductor muscle (AM), and hemolymph cells (HC) tissues were assayed for NV by the reverse transcription polymerase chain reaction (RT-PCR) method. An intemal RNA standard control was added to the RT-PCR to identify the presence of inhibitors to RT-PCR. NV titers in DD tissues before and after depuration were estimated using quantitative RT-PCR end-point dilution. NV was found in the alimentary tract (DD or St) at all concentrations of input virus, but was present more frequently after exposure to higher levels of virus. NV was detected in AM and HC only following exposure to higher levels of virus. In experiments where depuration by oysters was continued for 48 h, depuration of bacteria was efficient (95% reduction of bacteria), but minimal (7%) reduction of NV titers from DD tissues was detected. These findings indicate that NV can localize both within and outside the alimentary tract of shellfish, and NV is poorly depurated using conditions favorable for E. coli depuration.

Genetic basis of opine dehydrogenase activities in the Pacific oyster, Crassostrea gigas

Two polymorphic gene loci coding for enzyme proteins responsible for multiple opine dehydrogenase activities are expressed in the adductor muscle of the Pacific oyster, Crassostrea gigas. One locus, Strdh( Alpdh-1), codes for an isozyme that demonstrates highest catalytic activity with glycine, but is also capable of using α- l-alanine, l-serine and β-alanine as substrates. The second locus, Alpdh- 2, codes for an isozyme specific to α- l-alanine. Electrophoretic gels stained using α- l-alanine as substrate reveal presence of both isozymes in adductor muscle tissues. The STRDH(ALPDH-1) isozyme alone is detected in adductor muscle, with glycine as substrate, whereas only ALPDH-2 is detected in hepatopancreas, mantle and gill tissues with α- l-alanine. Only two enzyme proteins are responsible for multiple opine dehydrogenase activities in the adductor muscle of the oyster. The value of gene-enzyme specific allozyme patterns for identification of, and discrimination between, enzyme proteins possessing broad substrate specificity is briefly discussed.

Stress-70 protein induction in Mytilus edulis: Tissue-specific responses to elevated temperature reflect relative vulnerability and physiological function

The exposure of organisms to environmental stressors affects the expression levels of certain “stress proteins” that play an important role in protein homeostasis and stress tolerance. We have used an antibody to monitor this response to elevated temperature in the gill, mantle and muscle tissues of the mussel Mytilus edulis. The antibody detected four isoforms of the highly conserved stress-70 family of proteins, which appear homologous with the hsp70, hsc70, hsp72, and grp78 proteins that are detected by the same antibody in humans. Compared with mantle and adductor muscle tissues, gill tissue showed much the greatest increase in levels of both the 70 and 72 kDa proteins. Levels of the 70 and 72 kDa proteins increased for the first 48 hours of heat stress in the gill, and subsequently decreased between 48 and 72 hours. A 78 kDa protein was present in the gill and mantle tissues, but was absent from the adductor muscle. Alternatively, the 70 kDa protein was more abundant in unstressed adductor muscle than in unstressed gill or mantle tissues. Results are discussed in terms of the proposed cellular locations and function of these proteins, the processes contributing to thermally-induced death, and their implications for our understanding of how temperature affects the physiology, ecology and distribution limits of marine organisms.

Growth and content of energy reserves in juvenile sea scallops, Placopecten magellanicus, as a function of swimming frequency and water temperature in the laboratory

The effects of swimming frequency and water temperature on shell growth, tissue mass, and stored energy reserves of juvenile sea scallops, Placopecten magellanicus Gmelin, were examined in a factorial laboratory experiment spanning six weeks in July and August 1992. Individually tagged scallops of similar initial size (22.5±0.1 mm shell height, n=240) were induced to swim to exhaustion at three different swimming frequencies (every day, twice a week, or not at all) in two different water temperature regimes (4 to 7 or 7 to 13°C). The scallops were fed an ad libitum mixture of cultured microalgae. At the end of the experiment, cumulative increase in shell height, dry weight of soft tissues, condition index of dry adductor muscle (adductor muscle dry weight/soft tissue dry weight x 100) and total carbohydrate content of dry adductor muscle were measured for each scallop. Scallops at the higher temperature had significantly greater shell heights, and were in better metabolic condition as evidenced by significantly higher condition indices and muscle carbohydrate contents. The dry soft tissue weights did not differ significantly from their low temperature counterparts. Swimming frequency had no significant effect on shell height, dry tissue weight, or carbohydrate content, but condition index of the adductor muscle increased significantly with swimming frequency. These results show that not only was there no cumulative cost of swimming in terms of shell growth, total soft tissue weight, or carbohydrate content in young scallops, but that condition of adductor muscle tissue was higher in scallops that swam.

Cadmium and lead in tissues of scallops from Port Phillip Bay, Australia

Levels of Cd and Pb in adductor muscle, gonad and other tissues (i.e. viscera, mantle and gill) of the scallop (Pecten alba) collected from four sites of Port Phillip Bay, Australia were determined. Cd in gonad and other tissues (3.8 ± 0.1 and 3.76 ± 0.69 μg/g dry wt. respectively) were similar but significantly higher than that in the adductor muscle (2.71 ± 0.3 μg/g dry wt.). Pb in gonad and other tissues (18.75 ± 3.88, 14.06 ± 0.72 μg/g dry wt. respectively) were also significantly higher than that in the adductor muscle (5.54 ± 0.78 μg/g dry wt.). The results indicated that Cd and Pb are mainly sequestered in gonads and other tissues but not adductor muscle. The mean concentration of Cd in all tissues from all sites were under the Australian statutory limit. Although levels of Pb in adductor muscle from all sites were also below the limit, levels of Pb in edible parts (gonads and adductor muscle) of scallops from Williamstown and Frankston were over the Australian health standard. The level of Pb was 2.5 to 4.5 times higher than that of Cd in the same tissue type. Concentrations of both metals in scallops tend to decrease from north to south and east-west, and correlated with known point source discharges in the catchment area of the Bay.

Cadmium and lead in tissues of scallops from Port Phillip Bay, Australia

Levels of Cd and Pb in adductor muscle, gonad and other tissues (i.e. viscera, mantle and gill) of the scallop (Pecten alba) collected from four sites of Port Phillip Bay, Australia were determined. Cd in gonad and other tissues (3.8 ± 0.1 and 3.76 ± 0.69 µg/g dry wt. respectively) were similar but significantly higher than that in the adductor muscle (2.71 ± 0.3 µg/g dry wt.). Pb in gonad and other tissues (18.75 ± 3.88, 14.06 ± 0.72 µg/g dry wt. respectively) were also significantly higher than that in the adductor muscle (5.54 ± 0.78 µg/g dry wt.). The results indicated that Cd and Pb are mainly sequestered in gonads and other tissues but not adductor muscle. The mean concentration of Cd in all tissues from all sites were under the Australian statutory limit. Although levels of Pb in adductor muscle from all sites were also below the limit, levels of Pb to edible parts (gonads and adductor muscle) of scallops from Williamstown and Frankston were over the Australian health standard. The level of Pb was 2.5 to 4.5 times higher than that of Cd in the same tissue type. Concentrations of both metals in scallops tend to decrease from north to south and east-west, and correlated with known point source discharges in the catchment area of the Bay.

Influence of Density and Depth on the Growth of Juvenile Sea Scallops (Placopecten magellanicus) in Suspended Culture

We examined the influence of depth and stocking density on the growth and survival of juvenile sea scallops (Placopecten magellanicus) in suspended culture at Gascons, Baie des Chaleurs. An increase in density greatly reduced the growth of the shell, adductor muscle, and other tissues, possibly because of lower food availability and diminished space. Growth was also influenced by depth and was greater at 9 m than at 21 m. However, the effect of depth was largely masked by the effect of stocking density and fouling of pearl nets. The pattern of seasonal variations in growth varied with the parameter used to quantify growth, and the changes were correlated with temperature and with chlorophyll a in one size fraction (0.7–5 μm). Survival was high at all depths and densities studied. Maximum growth was obtained at a density of 50 scallops∙net−1. However, the growth was only slightly reduced at 100 scallops∙net−1 and thus, this would be an ideal stocking density for growing scallops commercially if the objective is ear-hanging or bottom-seeding after 1 yr of suspended culture.

Synergistic effect of insulin-like growth factor-I administration on the protein-sparing effects of total parenteral nutrition in fasted lambs.

Using primed constant isotopic infusions, we investigated the effects of recombinant human insulin-like growth factor-I (IGF-I) infusion on protein kinetics in both fasted and parenterally fed (TPN) lambs. Infusion of IGF-I at a dose of 50 micrograms/kg.h in fasted animals increased (P less than 0.005) the mean plasma IGF-I concentration from 77.5 +/- 9.7 to 454.4 +/- 51.4 ng/ml. During IGF-I infusion the rate of net protein catabolism (NPC) was decreased (P less than 0.005) by 17% from 3.5 +/- 0.2 to 2.9 +/- 0.2 g/kg.day, and the rate of appearance (Ra) of leucine in plasma decreased (P less than 0.01) from 5.0 +/- 0.4 to 3.4 +/- 0.4 mumol/kg.min. In addition, the fractional synthetic rate of protein in cardiac and diaphragmatic muscle increased by 100% (P less than 0.05) during the same period. After 3 h of TPN, the rate of NPC was decreased (P less than 0.01) in the TPN animals compared to that in their fasted counterparts (1.89 +/- 2.27 vs. 4.1 +/- 0.2 g/kg.day, respectively). The rate of NPC was further decreased after another 300 min of TPN to 0.76 +/- 0.27 g/kg.day. However, the Ra of leucine was not changed compared to the initial value. Infusion of IGF-I concurrently with TPN reversed (P less than 0.001) the rate of NPC from 1.02 +/- 0.21 g/kg.day after 180 min of TPN alone to a state of net protein gain of 0.14 +/- 0.19 g/kg.day after a further 300 min of combined IGF-I and TPN infusion. The Ra of leucine decreased (P less than 0.01) from 3.9 +/- 0.8 to 2.5 +/- 0.47 mumol/kg.min during IGF-I and TPN infusion. Similarly, the fractional synthetic rates of protein in cardiac muscle, diaphragm, adductor muscle, psoas muscle, and hepatic tissue were increased (P less than 0.05) compared to those in animals that received only TPN. The protein-sparing effects of IGF-I and TPN were synergistic, and the infusion of both agents resulted in the induction of a protein anabolic state within 60 min of commencing IGF-I infusion. In contrast, neither IGF-I nor TPN alone resulted in a state of net protein anabolism, and neither had an effect on protein kinetics until 120 min into the infusion. Consequently, IGF-I shows considerable potential as an anticatabolic agent when used synergistically with nutritional support.

Lipid composition of eggs and adductor muscle in giant scallops (Placopecten magellanicus) from different habitats

Scallops (Placopecten magellanicus Gmelin) were collected during August 1989 from shallow water (10 m) and deep water (31 m) habitats at Sunnyside, Trinity Bay, Newfoundland, to compare the lipid composition of eggs and adductor muscle tissue. Less favorable food levels and lower temperature conditions associated with deeper water have previously been shown to produce slower growth and reduced fecundity in individuals from this habitat. Triacylglycerol reserves consistently accounted for 60% of the total lipids present in both groups. The total lipid content of the eggs and the composition of their triacylglycerol fatty acid pools were similar in shallow water and deep water scallops, indicating very little if any nutritional difference between the two groups. Relative to their counterparts from shallow water, individuals from deeper water contained higher proportions of docosahexaenoic acid [22:6(n-3)] in the egg phospholipids and higher levels of 24-methylenecholesterol (a phytosterol commonly found in diatoms) in the adductor muscle. Differences in fatty acid composition are interpreted as biochemical adjustments of cell membranes to increase membrane fluidity, thereby compensating for the lower temperatures prevailing at the greater depth.

Expression of overdominance for specific activity at the phosphoglucomutase-2 locus in the Pacific oyster, Crassostrea gigas.

Environmental and genetic components of specific activity variation at the phosphoglucomutase-2 locus in the Pacific oyster, Crassostrea gigas, were examined to assess the direct role played by this polymorphism in a heterozygosity/growth relationship. Both environmental variables studied, season and intertidal position, exerted highly significant effects on phosphoglucomutase specific activity but no interactions occurred between these factors and Pgm-2 genotype. Highly significant differences were also detected between Pgm-2 genotypes. The three most common heterozygotes (Pgm-2(92/100), Pgm-2(96/100) and Pgm-2(100/104) consistently expressed greater specific activities than the Pgm-2(92/92), Pgm-2(96/96), Pgm-2(100/100) and Pgm-2(104/104) homozygotes. Overall, the specific activities of heterozygotes for the Pgm-2(100) allele exceeded heterozygotes by 24% and 20% in the mantle and adductor muscle tissues, respectively. Heterozygotes formed between the three less frequent Pgm-2(92), Pgm-2(96) and Pgm-2(104) alleles differed sharply from those possessing the Pgm-2(100) allele in being indistinguishable from homozygotes. The possibility of these patterns arising from the undetected presence of an inactive Pgm-2 allele was examined and found to be inconsistent with all of its predicted effects on the specific activity data. Genuine overdominance was shown to be capable of explaining the specific activities of ten structural locus genotypes, allelic frequency distributions in natural populations, and the maintenance of the enzyme polymorphism in a balanced state. The results provide evidence favoring the overdominance explanation for one locus involved in a heterozygosity/growth relationship and suggest that the reported effects of this locus on adult body weight may have been caused by the greater flux capacities of heterozygotes for the Pgm-2(100) allele.

Changes in intracellular free amino acids in tissues of the caged mussel,Elliptio complanata, exposed to contaminated environments

Intracellular tissue concentrations of free amino acids (FAA) were monitored in caged mussels (Elliptio complanata) exposedin situ for 27–29 days and 77–79 days in the Yamaska River watershed (Quebec, Canada). Total concentrations of FAA (nmol/mg wet weight) increased in both mantle and adductor muscle tissue at several sites impacted by agricultural runoff and urban effluent from municipal sewage and light industries when compared to levels in mussels located at a site with little anthropogenic impact. Consistent changes in the per cent composition of individual FAA to the total FAA pool included decreases in serine, threonine, glycine and valine as well as increases in glutamic acid and glutamine at 27–29 days but results were not consistent with longer exposure and varied amongst sites. Few changes in total or individual FAA were observed in gill tissue. The results suggest that increases and/or decreases in total FAA in some tissues of freshwater bivalves may be indicative of generalized stress induced by a variety of environmental factors and may be useful as anin situ biochemical index of toxicity.

Tributyltin contamination around an oil terminal in Sullom Voe (Shetland)

This report provides clear evidence of tributyltin (TBT) contamination of coastal waters close to an oil terminal handling large tankers. Dogwhelk populations from Sullom Voe, Shetland, have been examined for the development by females of certain male sexual characteristics (e.g. a penis and vas deferens). This condition, termed imposex, is a response to exposure to tributylin compounds, and can be quantified by use of the relative penis size index (RPSI). Dogwhelk populations throughout Sullom Voe were strongly affected by TBT (RPSI 34 to 81%), and up to 90% of the females in the oil terminal area were sterile. Queen scallops collected in the Voe contained enhanced concentrations of tin in adductor muscle and gonad tissue (0·02 to 0·23 mg kg −1 wet weight), but it is considered unlikely that their growth and development is adversely affected. Tin was rarely detected in scallops, queens, or dogwhelks outside the Voe, although the development of a vas deferens in many of the female dogwhelks indicated a degree of contamination of the open waters of Yell Sound. TBT was detectable (2 ng litre −1 as tin) in only two sea water samples taken from the terminal area.

Hyperosmotic volume regulation in the tissues of the mussel Mytilus edulis

1. 1. Alanine and glycine were the principal amino acids involved in FAA accumulation during hyperosmotic stress. 2. 2. Alanine accumulated most rapidly in mantle and slowest in the adductor muscle. 3. 3. Glycine increased most rapidly in the digestive gland and at approximately equal rates in adductor and mantle tissues. 4. 4. There was no significant variation in the concentration of ammonia in adductor muscle or mantle tissue during 70 hr following transfer from 15 to 30‰ seawater; changes in the concentration of ammonia in digestive gland were not correlated with amino acid accumulation.