Scallop Muscle Research Articles

Polarographic Studies on the Nature of Cadmium in Scallop, Oyster, and Lobster

Free and bound forms of cadmium were determined in raw shellfish by use of differential pulse polarography and atomic absorption spectrophotometry. Free cadmium is defined by its polarographic peak potential of −0.62 ± 0.02 V (saturated calomel electrode) in solvent washed ammonium sulfate extracts. Bound cadmium was determined by subtracting the free cadmium from the total cadmium present in the meat. Both scallop (various species) and American lobster (Homarus americanus) muscle tissues contain no free cadmium. Oyster (various species), on the other hand, had a considerable percentage (~50%) of its total cadmium present as free cadmium, a phenomena as yet unexplained. The detection limit for free cadmium is approximately 0.05 μg/g raw tissue. Key words: cadmium, polarography; free cadmium, oyster, lobster, scallop

Occurrence of toxic bivalves in association with Gonyaulax planktons in Ise, Owase, and Ofunato Bays.

The occurrence of toxic bivalves was surveyed in several bays in association with Gonyaulax planktons. Warious bivalves, such as short-necked clam and mussel, collected in April and May, 1976, in Ise Bay showed a maximum toxicity of 100 MU/g of whole soft body. The mussel collected in January and February, 1977, in Owase Bay exhibited a maximum toxicity of 70 MU/g of whole soft body. In the former case, a Gonyaulax bloom occurred almost in parallel with the appearance of toxic bivalves, indicating their close association. In the latter case, no bloom was observed. On the other hand, as high a toxicity as 800 MU/g was encountered with the mid-gut gland of scallop collected in May, 1976, in Ofunato Bay where no visible Gonyaulax bloom has so far been observed. The toxicity values of the ovary and adductor muscle of scallop were 45 and 20 MU/g, respectively.

D-.ALPHA.-iminopropioacetic acid isolated from the adductor muscle of scallop.

In the adductor muscle of the scallop, Patinopecten yessoensis, two acidic amino acids were detected and isolated by ion exchange chromatography. One, obtained as needles, was identified as meso-α-iminodipropionic acid (I), which has recently been isolated from the muscle of the squid Todarodes pacificas. The other compound, obtained as prisms, was inferred to be D-α-iminopro-pioacetic acid (II) by elemental analysis and mass, NMR, ORD, and IR spectrometries; this was confirmed by comparison with data from an authentic specimen. In the liquid chromatography the peak of II appeared between cysteic acid and taurine, overlapping practically with that of I. It is very interesting to note that both I and II have a D-alanine moiety in the molecule, as do octopine and lysopine.

Ascaridoid nematodes of amphibians and reptiles: Sulcascaris

ABSTRACTThe genus Sulcascaris is upheld and redefined. Sulcascaris sulcata from Chelonia mydas and Caretta caretta is redescribed, from Rudolphi's type material and material from the Mediterranean and Western Pacific, demonstrating that the excretory pore opens between the subventral lips and that the excretory cell is bilateral, comprising a short filamentar right component and a more capacious ribbon-like left component containing the nucleus. The phylogenetic significance of this form of excretory system occurring in an ascaridoid of a marine reptile is discussed. It is concluded from comparative studies, based on measurements, sections and electron scanning micrographs, that fourth stage larvae of S. sulcata collected from the stomach of turtles are identical with fourth stage ascaridoid larvae found in the adductor muscle of scallops (Amusium balloti and Chlamys sp.) and that turtles become infected with this species by eating bivalves. Adult S. sulcata were obtained from tank-reared C. caretta fed with encapsulated larvae from scallops.

ホタテガイ閉殻筋横紋部から調製したミオシンの性質

Myosin was prepared from the striated adductor muscle of giant ezo scallop, patinopecten yessoensis, by the original method of BÁRÁNY et al. This myosin showed the typical biological activity of myosin as already known tor rabbit myosin; that is, high ATP hydrolyzing activity and actin-binding ability. The actin-bingding ability of this myosin was examined by measuring the increase in ATP-sensitivity, superprecipitation, the enhancement of Mg2+-ATPase and the stabilization of Ca2+-ATPase for thermal denaturation. The first order rate constants for the thermal denaturation of Ca2+-ATPase (KD) were determined to be 22×10-4•sec-1 at 30°C, and 61-128×10-4•sec-1 at 35°C, while those of rabbit myosin were 1.5×10-4•sec-1 at 30°C, and 3.7×10-4•sec-1 at 35°C. SDS-gel electrophoresis indicated that a small amount of paramyosin and a trace of actin remained in this myosin preparation.

Regulatory light chains in myosins

Scallop myosin molecules contain two moles of regulatory light chains and two moles of light chains with unknown function. Removal of one of the regulatory light chains by treatment with EDTA is accompanied by the complete loss of the calcium dependence of the actin-activated ATPase activity and by the loss of one of the two calcium binding sites on the intact molecule. Such desensitized preparations recombine with one mole of regulatory light chain and regain calcium regulation and calcium binding. The second regulatory light chain may be selectively obtained from EDTA-treated scallop muscles by treatment with the Ellman reagent (5,5′-dithiobis(2-nitrobenzoic acid)): treatment with this reagent, however, leads to an irreversible loss of ATPase activity. The light chains obtained by treatment with EDTA and then DTNB are identical in composition and function. A different light chain fraction obtained by subsequent treatment with guanidine-HCl does not bind to desensitized or intact myoflbrils and has no effect on ATPase activity. Regulatory light chains which bind to desensitized scallop myofibrils with high affinity and restore calcium control were found in a number of molluscan and vertebrate myosins, including Mercenaria, Spisula, squid, lobster tail, beef heart, chicken gizzard, frog and rabbit. Although these myosins all have a similar subunit structure and contain about two moles of regulatory light chain, only scallop myosin or myofibrils can be desensitized by treatment with EDTA. There appear to be two classes of regulatory light chains. The regulatory light chains of molluscs and of vertebrate smooth muscles restore full calcium binding and also resensitize purified scallop myosin. The regulatory light chains from vertebrate striated, cardiac, and the fast decapod muscles, on the other hand, have no effect on calcium binding and do not resensitize purified scallop myosin unless the myosin is complexed with actin. The latter class of light chains is found in muscles where in vitro functional tests failed to detect myosin-linked regulation.

Metabolism of Pyruvate in Postmortem Adductor Muscle of the Sea Scallop (Placopecten magellanicus) During Iced Storage

Glycolytic metabolic pathways in postmortem adductor muscle of the sea scallop (Placopecten magellanicus) during iced storage were studied by means of 14C-pyruvate injected into the muscles. Ion-exchange fractionation of perchloric acid extracts of muscle into cationic, anionic, and neutral components showed that the radioactivity derived from 14C-pyruvate was rapidly incorporated into the cationic fraction during the postmortem storage period. Subsequent ion-exchange chromatography revealed that most of the radioactivity in the cationic fraction was distributed among three major peaks, whose components were identified by paper chromatography as (Peak I) alanine, (Peak II) α-amino-n-butyric acid and an unidentified compound, and (Peak III) octopine. These findings indicate that the disposition of pyruvate in postmortem scallop muscle is mainly via two pathways: transamination to amino acids, and reductive condensation with arginine to octopine. This metabolic pattern in muscles injected immediately after shucking (0-day series) did not differ significantly from that in muscles injected after preliminary storage of the shucked meats for 4 days in ice (4-day series).

Chemical and conformational events in regions of the myosin.

AbstractStructural changes in myosin may take place within the heavy chains, or may represent rearrangement of subunits. Changes induced by ATP and possibly restricted to the heavy chains are indicated by several different optical studies, including changes in absorbence of aromatic residues (1), changes in the fluorescene of dyes coupled to myosin (2), changes in electron spin resonance spectrum (3), and changes in the intrinsic fluorescence of tryptophan residues (4, 5). A calcium dependent subunit rearrangement in scallop myosin is indicated by fluorescene depolarization studies (Cheung and Szent‐Györgyi, unpublished observations). In scallop muscles, calcium regulates contraction by directly reacting with myosin (6), and the changes in the quaternary structure of myosin are likely to be related in the way calcium control works.At first I will disucss the changes of fluorenscene that Drs. Weber, Fasman, and I have described several years ago (4). Then I will speculate on the implications of a subunit rearrangement on the mechanism of regulatory light chain funciton.

アカザラガイ閉殻筋からアクトミオシンの調製

Actomyosin was prepared from the striated adductor muscle of akazara scallop. 1) Akazara scallop actomyosin showed the well-known characteristics, that is, anomalous viscosity, high ATP-sensitivity, marked ATP-hydrolyzing activity, and superprecipitation. These are very similar to those of actomyosin from rabbit skeletal muscle. 2) The Ca2+-ATPase activity of akazara scallop actomyosin was activated continuously as the KCl concentration increased from 0.06 to 0.31M, and reached about two fold at 0.31M KC1, while that of carp actomyosin was decreased steadily as the KCI concentration was increased from 0.06 to 0.5M. 3) The Ca2+-ATPase specific activity of akazara scallop actomyosin increased 4.7 fold up on the addition of 1.25M urea; on the other hand, the activity of carp actomyosin rapidly decreased on the addition of urea. 4) The rate constants for the denaturation of akazara scallop actomyosin Ca2+-ATPase were calculated as 1.6×10-5 sec-1 at 30°C, 36.9×10-5 sec-1 at 35°C and 249.5×10-5 sec-1 at 40°C. These values were comparable with those of yellowtail actomyosin.

Accelerated Nucleotide Degradation and Glycolysis During Warming to and Subsequent Storage at −5 C of Prerigor, Quick-frozen Adductor Muscle of the Sea Scallop (Placopecten magellanicus)

During slow warming of prerigor, quick-frozen scallop meats from −26 to −5 C, arginine phosphate and ATP were split rapidly between −8 and −6 C (in about 2 h), resulting in the accumulation of some ADP, and of large amounts of AMP, equivalent to 85% of the ATP originally present. Concomitant activation of glycolysis caused a substantial increase in fructose 1,6-diphosphate (FDP) concentrations, and smaller increases in the hexose monophosphates (HMP) and in octopine. The relatively low freezing point of prerigor scallop muscle, found to be −1.4 C, may be implicated in the stimulation of metabolic activity at a temperature as low as −5 C; the rates were faster than at 0 C and occurred at subfreezing temperatures considerably lower than those for most fish muscle.With continued storage at −5, FDP decreased as HMP concentrations rose sharply to maximum levels at 24 h; octopine accumulation was slower, attaining maximum concentrations at 5 wk. Rates of AMP degradation and of hypoxanthine accumulation were similar to those in unfrozen, iced scallop muscle, indicative of differential effects of temperature on the various metabolic enzymes.Because of the extensive metabolic activity in scallop muscle at temperatures near −5, the optimal quality of prerigor quick-frozen meats may be affected adversely by current commercial distribution and marketing practices where warming to temperatures just below the freezing point may be encountered.

Hexose Monophosphate Accumulation and Related Metabolic Changes in Unfrozen and Thawed Adductor Muscle of the Sea Scallop (Placopecten magellanicus)

The hexose monophosphates (glucose-6-phosphate (G6P), fructose-6-phosphate, and glucose-1-phosphate) accumulate postmortem in scallop adductor muscle (meats) during chill storage, increasing from only traces at death to levels totalling about 10 μmole/g after 8–10 days. In both unfrozen and thawed meats, G6P accounted consistently for 80–85% of the total hexose monophosphate, over a wide range of actual concentrations. Quick freezing at any time postmortem did not affect the concentrations of hexose monophosphates or related metabolic constituents. Thawing of the prerigor-frozen muscle, however, either slowly or rapidly, resulted in considerable G6P formation, and accelerated markedly the subsequent rate and extent of G6P production. The exceptionally high levels (− 20 μmole/g) reached in the thawed meats after 1–2 days at 5 C are implicated in the development of burned flavors, odors, and discolorations (i.e. Maillard browning reactions) observed in these thawed meats when cooked. While thawing of the prerigor-frozen muscle led to some hypoxanthine (Hx) and octopine formation, the subsequent rate of Hx accumulation at 5 C was three times faster in the thawed meats than in unfrozen meats. In meats frozen postrigor, thawing resulted in negligible change in concentrations of the metabolites; subsequent patterns of change during storage differed little from those in unfrozen muscle, although Hx accumulation was more rapid. Hx content showed potential as an index of quality in thawed scallop muscle.

Regulation of lactic dehydrogenase in the giant scallop, Placopecten magellanicus (Gmelin)

1. Glutamate and aspartate, and the Krebs cycle intermediates, in contrast to mammalian skeletal muscle, decreased the activity of lactic dehydrogenase in the adductor muscle of the giant scallop. 2. An explanation for these observed effects is offered.

Glycolysis and gluconeogenesis in the giant scallop, Placopecten magellanicus (gmelin)

1.1. It would appear from the relative activities of key glycolytic enzymes that succinate is the main end product of glycolysis in both the mantle and the adductor muscle of the giant scallop.2.2. All but one of the enzymes involved in succinate formation were found to be cytoplasmic.3.3. The enzymes of the Bücher shuttle were found in the adductor muscle.4.4. The high activities of phosphoenolpyruvate carboxykinase and fructose diphosphatase are compatible with active glycogen synthesis.

Sarcoplasmic reticulum in the cross-striated adductor muscle of the bay scallop, Aequipecten irridians.

The fine structure of the striated adductor muscle of the bay scallop, Aequipecten irridians has been investigated with particular emphasis on the sarcoplasmic reticulum. Each cell of the muscle contains a single myofibril. There is no transverse tubular system in this muscle. The cisternae of the sarcoplasmic reticulum are all interconnected by means of tubular elements. This extensive, interconnected system of flattened cisternae and tubular vesicles is distributed randomly with respect to the sarcomere and is in close association with the sarcolemma.

ENZYMATIC DEAMINATION OF ADENOSINE MONOPHOSPHATE (AMP), ADENOSINE AND ADENINE BY SALMON, CRAB AND SCALLOP MUSCLE EXTRACTS

SUMMARYCrude extracts of pink and coho salmon fillets contain both adenosine aminohydrolase (EC 3.5.4.4.) and 5′‐AMP‐aminohydrolase (EC 3.5.4.6.1. Similar extracts from king and Tanner crab meat and from scallop adductor muscle contain adenosine aminohydrolase but not 5′‐AMP‐aminohydrolase. Adenine aminohydrolase activity was not detected in salmon, crab or scallops. These results suggest that the enzymatic deamination of 5′‐adenosine monophosphate (AMP) will contribute to the 5′‐inosine monophosphate (IMP) content of salmon fillets but will not contribute significantly to the IMP content of crab or scallop muscles.

Principal Acid-Soluble Nucleotides in Adductor Muscle of the Scallop Placopecten magellanicus and Their Degradation during Postmortem Storage in Ice

In scallop adductor muscle stored at 0 C, postmortem degradation of adenosine triphosphate (ATP), the predominant nucleotide at death, primarily follows the route ATP → adenosine diphosphate (ADP) → adenosine monophosphate (AMP) → adenosine → inosine → hypoxanthine (Hx). In one lot of scallops, however, inosine monophosphate (IMP) was present as an intermediate along with AMP. Hence, an alternate pathway, similar to that in fish muscle, whereby AMP is degraded to inosine and Hx via IMP rather than adenosine, may exist under certain (undefined) conditions. ATP dephosphorylation was much slower than in fish muscle; however, a rapid turnover of the intermediates in the degradative sequence, indicating relatively high activities of the enzymes catalyzing these reactions, resulted in the formation of appreciable amounts of Hx (3–4 μmole/g) within the edible storage period. In preliminary tests, taste scores correlated well with Hx contents, suggesting that measurement of Hx content may be a useful index of quality in scallop meats.Column chromatographic analyses showed that adenine nucleotides and their degradation products accounted for about 90% of the total acid-soluble purines and pyrimidines in scallop adductor muscle, with nicotinamide adenine dinucleotide and uridine diphosphate glucose as the principal minor nucleotide constituents. The muscle also contained considerable amounts of homarine (2–3 μmole/g). Glycolysis showed no relation to nucleotide degradation, both processes demonstrating a relatively slow postmortem catabolic rate in scallop muscle.

ホタテガイ閉殼筋のエキスアミノ酸組成と酸可溶性燐

The adductor muscle of scallops consists of two kinds of muscles: One is a striated muscle and the other is a smooth muscle. These muscles are different from each other in some respects: In color, the striated muscle is slightly reddish, but the smooth muscle is rather white; in size, the former is almost nine times as large as the latter. Physiologically the former works in the instant closing of valves, while the latter keeps the valves closed. Furthermore, the striated muscle is more palatable than the other. With this in mind, the extractives from both the adductor muscles and the body juice of scallop, Pecten yessoensis, were analyzed for amino acid composition and organic and inorganic phosphorus contents. To the muscle homogenate or body juice 10 volumes of 1% picric acid solution were added. Then the extracts were passed through a column of Dowex 2X 10 to remove picric acid. Amino acids were determined by the Hitachi Amino Acid Analyzer Model KLA-3. The determination of phosphorus in a 0.6 N perchloric acid extract was carried out by the FISKE and SUBBAROW's method. No distinct difference was found in the amount of amino nitrogen between the two muscles. The same tendency was observed in the ratio of amino nitrogen to the total nitrogen. As for the amino acid content, glycine formed about 50% of the total amino acids, and taurine accounted for 23-42% in all the samples examined. Of the three samples, the striated muscle was the highest in phosphorus content and the body juice was the lowest. The content of arginine in the striated and smooth muscles was higher than that of the other amino acids except glycine, taurine, glutamic acid, and alanine. From these results, the authors have presumed that arginine phosphate acts as an energetic source in the two muscles.

Effect of Hematin Compounds on the Development of Rancidity in Muscle of Cod, Flounder, Scallops, and Lobster

Hemoglobin, catalase, myoglobin, and inorganic iron were added to blended muscle from cod, flounder, scallops, and lobsters to determine the effects of these various forms of iron on the oxidation of the muscle lipids as indicated by increased malonaldehyde and rancid odours. Hemoglobin and catalase were very active catalysts; myoglobin was relatively inert. Scallop muscle was slightly more susceptible to hemoglobin-induced rancidity than muscle from cod or flounder; lobster muscle was highly resistant. There was a difference in the odours accompanying the development of rancidity after the addition of free Fe++ and hemoglobin-bound Fe++. An increase in the free fatty acid content of the muscle retarded the hemoglobin-induced rancidity. Certain free amino acids, notably tryptophane and proline, also had an inhibitory action, whereas other amino acids had a prooxidant effect.

Production of Trimethylamine in Frozen Cod Muscle

Trimethylamine (TMA) was produced in frozen cod fillets and in scallop muscle under conditions where bacterial activity could not take place. The amounts formed were smaller than those which usually accompany bacterial deterioration of unfrozen fish. Decreases in storage temperature between −3 and −26 C reduced the rate of TMA formation. At −26 C no measurable increase of TMA was produced in cod fillets during storage periods up to 700 days.TMA formation appeared to be related to other chemical changes taking place in the frozen muscle. It followed shortly after the formation of free fatty acids and was almost simultaneous with changes taking place in the amounts of extractable protein.

Protein in Extracts of Prerigor and Postrigor Scallop Striated Muscle

The extraction of protein from the striated muscle (prerigor and postrigor) of scallop (Placopecten magellanicus) by salt solutions of various strengths and at pH 7 was investigated. With postrigor muscle the structural proteins appeared in the extract only at ionic concentrations (Γ/2) greater than 0.3.With prerigor muscle, most of the protein was extracted at Γ/2 = 0.15. A large part of this protein precipitated from the extract upon standing, and when redissolved in stronger salt solutions resembled myosin B in sedimentation behavior and ultraviolet absorption.