Purification and characterization of a chymosinlike protease from the gastric mucosa of harp seal (Pagophilus groenlandicus)

Four zymogens of acidic proteases A, B, C, and D were isolated from the gastric mucosa of harp seals by ion-exchange chromatography on a diethylaminoethyl-Sephadex A-50 column. The major zymogens were A and C, and the ratio of zymogen A to zymogen C was greater in extracts from 1-week-old animals than in extracts from adult animals. Zymogens A and C were further purified by affinity chromatography using carbobenzoxy-D-phenylalaninetriethylene tetramine Sepharose and gel filtration on a Sephadex G-100 column. Certain physical and catalytic properties of proteases A and C were compared with those of calf chymosin (EC 3.4.23.4) and porcine pepsin (EC 3.4.23.1). Zymogen C and the corresponding enzyme were homogeneous on analytical polyacrylamide gel electrophoresis. Zymogen A was homogeneous as judged by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis and high performance liquid chromatography, but was heterogeneous by polyacrylamide gel electrophoresis at pH 8.3. Zymogens A and C had molecular weights of 33 800 and 44 000, respectively, as estimated by SDS-polyacrylamide gel electrophoresis. Protease A had an isoelectric point of 4.90. Protease A was similar to calf chymosin with respect to several criteria. It had a higher ratio of milk-clotting to proteolytic activity than those of seal protease C and porcine pepsin and had a pH optimum of 2.2-3.5 for hemoglobin hydrolysis. It did not inactivate ribonuclease, had very low activity on N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine and lost activity in 6 M urea. These results indicate protease A is chymosinlike.

A two-active site one-polypeptide enzyme: the isomaltase from sea lion small intestinal brush-border membrane. Its possible phylogenetic relationship with sucrase-isomaltase

The enzyme responsible for all of the isomaltase activity and much of the maltase activity in the small intestine of the Californian sea lion (Zalophus californianus) was isolated by detergent solubilization of the brush-border membrane, followed by immunoadsorption chromatography using antibodies directed against rabbit sucrase-isomaltase. In 0.1% Triton X-100, sea lion isomaltase occurs as a monomer of Mr = 245,000 and is composed of a single polypeptide chain. As judged from the stoichiometry of the covalent binding of the affinity label, conduritol-B-epoxide, this polypeptide chain carries two enzymatically active sites; they are apparently identical and do not show either positive or negative cooperativity. In addition to cross-reacting immunologically with rabbit sucrase-isomaltase, sea lion isomaltase has similar overall enzymatic properties, with the exception of not hydrolyzing sucrose. The Alaskan fur seal (Collarhinus ursinus) has a two-active site isomaltase; however, in contrast to the sea lion, this animal is endowed with a small but significant sucrase activity. Along with (fully active) pro-sucrase-isomaltase, sea lion isomaltase is one of the very few examples of enzymes with more than one active site on a single polypeptide chain acting "in parallel" (rather than "in series"). Furthermore, this enzyme triggers some interesting questions on the phylogenetical pedigree of small intestinal sucrase-isomaltase.

Enzymatic adaptations to asphyxia in the harbor seal and dog

The activities of the glycolytic enzymes were determined in heart, liver, kidney cortex and cerebrum from the harbor seal (Phoca vitulina ) and the adult and newborn dog. Activities were similar in the four dog tissues as well as myocardium and brain tissue from both the newborn dog and seal. Most of the enzyme activities were markedly lower in kidney cortex and liver of the seal and the newborn dog, suggesting that the organs which are rendered ischemic in the diving seal or asphyxiated newborn dog have a lowered demand for glycolytic metabolism. This is perceived as an adaptation to prolong the time tissues can rely on anaerobic metabolism. Expression of the enzyme data in a 'similarity criterion' by dividing activity from an organ likely to be perfused during long diving or asphyxia (e.g., heart), by that from one rendered ischemic (e.g., kidney), yields a quotient which provides a convenient indicator of anaerobic potential. Such a treatment would reflect the contribution of a discrete tissue to the total anaerobic demand of the whole animal. The values thus generated for the glycolytic enzymes are generally higher in the seal and the newborn dog than in the adult dog, and suggest an index for determining the capacity of an animal to withstand repeated and variable asphyxia.

Characterization of ethoxyresorufin O-de-ethylase in grey seal Halichoerus grypus

Ethoxyresorufin O-de-ethylase (EROD), a typical mixed function oxidase enzyme, was studied in liver and kidney of adult and pup grey seals, Halichoerus grypus. EROD activity was present in most liver samples but was only barely detectable in a few of the kidney samples. Liver EROD activity was greatest at pH 7.5-8.0; activity increased with temperature from 20 degrees C to a plateau starting at about 33 degrees C and extending to 37 degrees C, and fell off sharply above 37 degrees C. Km values ranged from 3 X 10(-7) to 3 X 10(-6)M; Vmax ranged from 5 X 10(-12) to 1 X 10(-10) moles product formed X min-1 X mg protein-1. Liver EROD activity was not detectable in pups less than 1 day old, and activity increased with age in pups up to 5-12 days old. Adults had greater EROD activity than did pups.

Milk of northern fur seal: composition, especially carbohydrate and protein

The milk of northern fur seal was analyzed with special interest in carbohydrate and protein. High solids (61%) and fat (45.6%) were characteristics of its gross composition. Fatty acid distribution showed that more than 22% of the fatty acids had carbon chains longer than 20 and that approximately 70% contained one or more double bonds. Analysis of free sugars showed no lactose but 123 mg/100 ml of myo-inositol. In carbohydrates bound to casein, .99% of sialic acid and .2% of glucosamine were determined. The amino acid composition of casein showed higher tryptophan, lysine, serine, and glycine than bovine casein, and lower arginine, proline, and leucine. In whey, arginine, threonine, and valine were higher, whereas lysine, aspartic acid, isoleucine, and leucine were lower than in bovine whey. Amino acid patterns in casein and whey were similar to those of cat milk. The appearance of casein micelles was similar to bovine casein micelles. The mean diameter, however, was larger (approximately 330 nm). Electrophoretic pattern of casein showed five major bands in addition to minor components. One of the minor components was a glycoprotein, probably kappa-casein-like protein. The major whey protein had a mobility similar to that of bovine beta-lactoglobulin. No alpha-lactalbumin-like protein was observed.

The quantification of technical mixtures of PCBs by microwave plasma detection and the analysis of PCBs in the blubber lipid from harbour seals (Phoca vitulina)

Seven technical mixtures of polychlorinated biphenyls (PCBs) were quantified with gas-liquid chromatography-microwave plasma detection (g.l.c.-m.p.d.). These mixtures were then used to determine individual peak response factors for g.l.c.-electron capture detection (e.c.d.), which is used for the routine analysis of PCBs. PCB residues in the blubber lipid from harbour seals, found dead on the Dutch coast from 1972 to 1981 were analysed; 175 samples showed a log-normal distribution with a large coefficient of variation, which makes it difficult to detect differences between groups of harbour seals. Regression analysis showed a significant decrease of PCB content with increasing blubber thickness (BT). Relations between PCB content and age of the seal, and between PCB content and the year in which the seal was found are uncertain.

Hydrocarbon metabolism and cortisol balance in oil-exposed ringed seals, Phoca hispida

1. Ringed seals were exposed experimentally to oil contamination, by feeding of a [14C]naphthalene marked crude oil in fish for up to 4 days at a rate of 5 ml/day. 2. Mixed function oxygenase (MFO) activity, measured as aryl hydrocarbon hydroxylase in liver and kidney, was found to be induced, in particular in kidney tissue where the activity increased 3-fold. 3. MFO induction correlated with a high degree of conversion of crude oil hydrocarbons to water-soluble metabolites. Most of the radioactivity was found in the polar fraction of plasma and urine. 4. Plasma cortisol levels were somewhat elevated by captive holding, and increased markedly after oil-exposure. Cortisol half-life decreased after oil exposure from 1 3/4 to 1 hr.

Tissue sources and clinical application of four enzymes in phocid seals

Tissue distribution and plasma activity values of creatine kinase (CK), aldolase (ALS), gamma-glutamyltransferase (GGT), and leucine aminopeptidase (LAP) were determined in 6 ringed seals, Phoca hispida, and in 7 harp seals, P groenlandica. Muscle tissues had the highest activity of CK and ALS, though high activity of ALS was also in most other tissues. The LAP and GGT were mostly concentrated in the kidneys; tissue LAP activity was generally low. Reference plasma values were determined in 17 ringed and 15 harp seals. The CK and GGT, respectively, are recommended for monitoring exertional stress and hepatobiliary dysfunction in phocid seals.

Heptachlor epoxide in marine mammals

The presence of heptachlor epoxide in harbour seals (Phoca vitulina) and white-beaked dolphins (Lagenorhynchus albirostris) has been confirmed by chemical derivatization and mass spectrometric analyses. An unknown compound at a retention time close to half of heptachlor epoxide interfered in the determination by electron capture detector-gas chromatography. On a WCOT CP-Sil 7 column programmed from 85 to 175 degree C two poorly separated peaks could be detected. Heptachlor epoxide contents up to 1.7 mg/kg (on a fat basis) were obtained, which were about 200 times lower than the PCB levels. The same ratio was also observed in fish from the same area.

Mercury and selenium content and chemical form in human and animal tissue

The content, chemical form, and distribution of mercury and selenium were determined for selected samples of human and animal tissue by gas chromatography. Methylmercury averaged 38.7% of the total mercury content in homogenized human brain. For human heart, spleen, liver, kidney and placenta, methylmercury comprised 40.2%, 57.0%, 39.6%, 6.0% and 57.1% respectively, of the total mercury content. Similar results were obtained for the heart and liver of a whitetail deer. Methylmercury represented 9.1%, 62.9% and 24.1% of the total mercury content in seal liver, seal meat and deer meat, respectively. For all samples, a significant portion of the total selenium content, averaging 27%, was present as selenate (Se VI). Tissue selenium content did not correlate with the corresponding mercury content. In brain, heart and placenta, and in seal liver and meat, 53% to 80% of the total mercury content was water-extractable. For human kidney, liver and spleen, and deer meat, only 15% to 45% of the total mercury was extractable. On a percentage basis, inorganic mercury was more extractable than methylmercury, except for human kidney and liver, and deer meat. For all samples, except kidney, liver and deer meat, 55% to 76% of the total selenium content was water-extractable, Se VI being more extractable on a percentage basis than selenite (Se IV) and selenide (Se-II).

Nature of adenosine triphosphatase accelerating peptide from hydrolysate of fur seal muscle

Ultrafiltered fur seal muscle hydrolysate was divided into eleven fractions by gel filtration on Sephadex G-15. One of the fractions (Fraction G9) accelerated the ATPase activity of carp myosin B to a rate about two-fold faster than that of the control. Fraction G9 showed a single ninhydrin spot in its silica gel thin layer chromatograph, and gave a positive test for tryptophan by the p-dimethylaminobenzaldehyde method, while tests for tyrosine, and for arginine were negative. The ion exchange amino acid analysis of its acid hydrolysate showed a predominant content of lysine, nearly equivalent to the amount of tryptophan determined from its UV absorbancy and the p-dimethylaminobenzaldehyde method. The N-terminal amino acid analysis gave di-DNP-Lys as the sole DNP-amino acid. The structure of the ATPase accelerating peptide fraction, Fraction G9, was deduced to be Lys-Trp.

Fatty acid content of depot fat in the northern fur seal (Callorhinus ursinus)

The fatty acid content of depot fat samples from 15 northern fur seals (Callorhinus ursinus) were determined by gas-liquid chromatography. Callorhinus ursinus has a high proportion of short chain saturated acids: C10, C11, C12, C13, C15. Unsaturated longer chain acids C16:1, and C16:2, and C18:1 also were found. Results obtained are compared to a previously reported milk lipid analysis of the northern fur seal.

Organochlorine residues in harp seal (Phagophilus groenlandicus) tissues, Gulf of St. Lawrence, 1971, 1973

Levels of p,p'-DDT, p,p'-TDE, p,p'-DDE, dieldrin, polychlorinated biphenyls (PCBs), and HCB were determined in certain tissues of 31 harp seals (P hagophilus groenlandicus) taken from the Gulf of St. Lawrence during 1971 and 1973. The seals ranged in age from less than two weeks to 18 years. Mean concentrations of PCBs and sigma DDT in the various tissues were about the same sigma DDT levels were 1.64--9.88 ppm in adult seal blubber and 1.08--3.73 ppm in seal pup blubber. Organochlorine levels in harp seal samples taken in 1973 were similar to those reported by other workers for samples collected in the Gulf of St. Lawrence during 1967-71.

Occurrence and fate of organic and inorganic contaminants in marine animals

Most chemical contaminants occur in highest concentrations in coastal waters, often maximized in very localized areas. In general, this situation represents the exposure pattern for marine animals. However, the availability of contaminant to an organism depends not only on its concentration but also on its chemical nature, its physical state, and whether the source of exposure is the surrounding seawater or the diet. Depending on the type of exposure, uptake occurs across absorptive surfaces, such as those of the respiratory apparatus or gastrointestinal tract, where selectivity may occur, even among neighboring homologs. Deposition in tissues, accumulation, degradation, or depuration depends on tissue type, metabolic processes, detoxification mechanisms, and the adaptive status of a particular animal. This hypothesis is examined briefly for hydrocarbons, pesticides, other miscellaneous organic contaminants, heavy metals, and radionuclides. It is concluded that most data relate to occurrence and distribution. Considerably less information is available on the underlying biochemical processes.

Clinical blood values of the northern fur seal, Callorhinus ursinus. III. Comparison of eye fluid and serum values

The levels of 13 components in the serum and eye fluids of the northern fur seal, Callorhinus ursinus, are compared. The wide variations observed would appear to limit the usefulness of eye fluid values as a substitute for serum values.

Tissue distribution and plasma levels of liver enzymes in phocid seals

The distributions of alanine aminotransferase (AIAT), aspartate aminotransferase (AspAT), ornithine carbamyl transferase (OCT), and sorbitol dehydrogenase (SDH) were determined in the tissues of ringed seals, Phoca hispida, harp seals, P. groenlandica, and grey seals, Halichoerus grypus. In all species, AIAT, OCT, and SDH were concentrated primarily in the liver, while AspAT had a more widespread distribution. Species differences were noted in the distribution of AspAT. In grey and harp seals cardiac muscle generally contained the greatest concentration of activity while in ringed seals the highest activity was found in the liver. Reference plasma values were determined in six clinically normal captive ringed seals.

Plasma and tissue levels of dietary radiotocopherols in the harp seal, Phoca groenlandica

Plasma and tissue levels of dietary radiotracer-labeled tocopherols were examined in the harp seal, Phoca groenlandica. The d-alpha form showed much higher plasma maxima and retention than d,l-gamma-tocopherol. Concentration peaks occurred somewhat later but were greater when the vitamin was fed with Tween 80 than with herring and corn oil respectively. Greater plasma levels occurred with the use of herring oil as compared with corn oil. Seals previously maintained on a vitamin E deficient diet showed greater plasma maxima than seals not so deprived. Plasma and tissues generally showed maximum levels within 24 h postingestion. Tissue levels of labelled dietary alpha-tocopherol were examined by biopsy and postmortem studies in selected tissues of vitamin E deprived seals.

Intratracheal injection of antibiotics in the California sea lion, Zalophus californianus, and bottlenosed dolphin, Tursiops truncatus

Gentamicin and cephaloridine were administered by intratracheal injection to the California sea lion, Zalophus californianus, and the bottlenosed dolphin, Tursiops truncatus. Uptake and clearance of these antibiotics in the blood were monitored. In all cases, absorption through the respiratory mucosa resulted in blood levels approaching therapeutic concentrations despite low dosages.

Chlorinated hydrocarbon and PCB residues in tissues and lice of northern fur seals, 1972

DDT, dieldrin, and PCB contents of tissues and the sucking lice of the northern fur seal (Callorhinus ursinus) were studied in samples collected in July 1972 in the Pribilof Islands, Alaska. They included the analyses of two nursing cows and their two newborn pups, three 2-month-old pups, and the sucking lice inhabiting these animals, Antarctophthirus callorhini and Proechinophthirus fluctus. The sigmaDDT content of fat tissue was 5.2, 5.6 and 63 mug/g (-/x) for cows, newborns, and 2-month-old pups, respectively. Dieldrin appeared at trace levels. PCB residues (Aroclor 1254) were 5.8, 5.5, and 33 mug/g (-/x), respectively. The sigmaDDT content of blood was less than 0.01 mug/g for cows and newborns and 4.6 mug/g for 2-month-old pups. PCB's were found only in trace amounts in the blood of all animals except one 2-month-old pup which contained 3.4 mug/g. Lice contained 0.2-6 percent, respectively, of the sigmaDDT and PCB's detected. All residues were expressed on a wet-weight basis. Two-month-old pups had far higher residue levels than had cows. A high percentage of sigmaDDT occurred as the DDE metabolite: 60 percent in cows and newborn pups and 90 percent in 2-month-old pups.

Metabolism and temperature regulation in young harbor seals Phoca vitulina richardi

Metabolism and the ability to regulate core and peripheral temperatures under a variety of ambient conditions were studied in five unrestrained pups (less than 5 wk old) and four 3- to 5-mo-old harbor seals. Pups born with nonlanugo (adultlike) hair and little fat were able to swim in 5 degrees C water for several hours without becoming hypothermic. They were also found to tolerate 5 degrees C air temperature with the fur wet and exposed to a 35-knot wind. Basal metabolism in pups averaged 0.8 ml O2 g-1 h-1, which is 2.6 times the predicted value for an adult mammal of the same weight. Lower critical temperature in air was about 3 degrees C. Oxygen uptake in 3- to 5-mo-old seals under basal conditions was 0.5 ml g-1 h-1. Minimal thermal conductance values were .02 and .015 ml O2 g-1 h-1 degrees C-1 in pumps and 3- to 5-month-old seals, respectively. Appendages, and to a lesser extent the skin on the torso, cooled appreciably at lower air temperatures, and the flippers were kept just above freezing in subzero air. Tissue insulation provided by low peripheral temperatures and a high resting metabolic rate enable newborn and developing harbor seals to tolerate the low temperatures encountered in their natural environment.

Mercury and selenium in marine mammals and birds

Information is provided concerning the concentrations of mercury and selenium in tissues of marine animals. In marine mammals a 1:1 Hg/Se molecular increment ratio was found and an almost perfect linear correlation between mercury and selenium. It is suggested that marine mammals are able to detoxify methylmercury by a specific chemical mechanism in which selenium is involved. The results also indicate that the fate of methylmercury in fish-eating marine birds differs fundamentally from that in marine mammals.

The harbor seal Phoca vitulina concolor De Kay: comparative details of fatty acids in lung and heart phospholipids and triglycerides

The fatty acids of phospholipids and of triglycerides from the lungs and heart of the harbor seal Phoca vitulina concolor De Kay show distinctive differences from the depot (blubber) fat. Primarily, this is due to greatly elevated levels of 20:4ω6 in the phospholipids. Although these have about the same total C20 and C22 polyethylenic acids with five and six double bonds as the depot fat, they occur in different proportions emphasizing 20:5ω3 rather than 22:6ω3. The organ triglycerides resemble the phospholipids in saturated fatty acid composition and the depot fats in monoethylenic fatty acid composition, but have remarkably low levels of 20:5ω3, 22:5ω3, and 22:6ω3 compared to the depot fat. Comparisons are made with phospholipids from the lungs of the leatherback turtle Dermochelys coriacea coriacea Linnaeus but the novel trans-6-hexadecenoic acid found in the turtle lipids could not be detected in the seal lipids.

Strontium-90 and cesium-137 levels in tissues of fin whale (Balaenoptera physalus) and harp seal (Pagophilus groenlandicus)

90Sr and 137Cs were determined in 11 different tissues of the fin whale and 2 different tissues of the harp seal. Muscle tissue in most instances contained more 137Cs than did the other tissues that were examined. The average concentration of 137Cs in whale muscle was 4.5 pCi/g ash and in adult seal muscle was 2.5 pCi/g ash. The highest concentration (3.5 pCi/g ash) of 90Sr was found in whale blubber.

Metabolism of fatty acids in the southern elephant seal Mirounga leonina (L)

In general, the composition of the blubber of the southern elephant seal, determined by gas–liquid chromatography, is similar to that of other marine mammals. In this regard, the present work disagrees with an earlier study made on an individual of this species. The marked disappearance of the long-chain polyunsaturated acids in both the nursing cow and fasting pup suggests catabolism of these acids during nonfeeding periods. Support is given here for the contention that some fatty acids are transferred intact from the depot fat of the seal cow to her pup via the milk.