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PubMed1977

A study of the effects of methyl mercury, cadmium, arsenic, selenium, and a PCB, (Aroclor 1254) on adrenal and testicular steroidogeneses in vitro, by the gray seal Halichoerus grypus.

An in vitro study on the effects of the contaminants polychlorinated biphenyl (Aroclor 1254) (PCB), methyl mercury (MeHg), arsenic (As), cadmium (Cd), and selenium (Se) on the biosynthesis of steroid hormones in the gray seal (Halichoerus grypus) indicated altered steroid biosynthesis. Biotransformed delta4-androstene-3, 17-dione (delta 4A), dehydroepiandrosterone, 11-ketotestosterone (11-KT), and testosterone (T) were detected in all seal testicular incubates. Yields of 11-KT were greatly increased in the presence of Aroclor 1254. All contaminants except As and Se stimulated the in vitro biosyntheses of T, with the greatest increase in production of T being in the Cd-treated tissue. Cortisol (F), corticosterone (B), aldosterone (ALDO) but no cortisone (E), were biosynthesized by the seal adrenal tissue. Corticosterone (B) was the principal transformation product in all incubations with less B produced by the treated adrenals than by the control. The lowest yeild of B was achieved by the Se-treated adrenal. The yeild of ALDO was also lower in all contaminant treated incubations, with Se and Cd giving the greatest inhibition. More F was biosynthesized by all the treated adrenals than by the control. The greatest increase of production of F(6-fold) from progesterone was by the As-treated adrenal.

Acetylation↗

PubMed1996

Energy intake and utilisation by nursing bearded seal (Erignathus barbatus) pups from Svalbard, Norway.

In this study we measure energy intake via milk in nursing bearded seal (Erignathus barbatus) pups and determine how this energy is allocated into metabolism and storage of new tissues. This was accomplished using longitudinal mass gain records and the doubly labelled water technique on nursing pups in combination with cross-sectional data on changes in milk composition from bearded seal mothers. The pups (n = 3) were all less than a week old at the start of the experiments. Pups gained 3.3 +/- 0.4 kg.day-1 of which 50% was fat, 14% protein and 36% water. Average daily water influx for the pups was 69.5 +/- 9.0 ml.kg-1. day-1. Average CO2 production during the study period was 0.99 +/- 0.10 ml.g-1.h-1, which corresponds to a field metabolic rate of 642 +/- 67 kJ.kg-1. day-1, or 6.0 +/- 0.5 times the predicted basal metabolic rate according to Kleiber (1975). The pups drank an average of 7.6 +/- 0.5 kg of milk daily. This corresponds to a daily energy intake of 154 +/- 8 MJ, 47 +/- 14% of which was stored as new body tissue. Despite this high energy intake bearded seal pups do not get as fat as do other nursing phocids. This is in part due to their larger body size but also due to their very active aquatic lifestyle and the lower and more consistent fat content of the milk compared to other phocid species. Bearded seal mothers forage during lactation and may also be involved in teaching their pups to feed independently. All these data suggest that the lactation strategy of bearded seals differs from the phocid norm.

Animals↗

PubMed1996

The "Phoca standard": an external molecular reference for calibrating recent evolutionary divergences.

Comparison of the complete mitochondrial DNA (mtDNA) of the high-Arctic ringed seal (Phoca hispida) and the sub-Arctic harbour (P. vitulina) and grey (Halichoerus grypus) seals shows that they are genetically equidistant from one another. We relate the evolutionary divergence of the three species to expanding glaciation in the Arctic Basin and establish, in conjunction with mtDNA data, a standard reference for calibration of recent divergence events among mammalian taxa. In the present study, we apply the "Phoca standard" to the dating of divergences within the hominid phylogenetic tree. After determining the relative rates of substitution over all mitochondrial protein-coding genes in the different evolutionary lineages, we estimate that humans and chimpanzees diverged from each other 6.1 Mya (95% confidence limits: 5.2-6.9 Mya). The corresponding lower-limit divergence between common chimpanzee, Pan troglodytes, and pygmy chimpanzee, P. paniscus, occurred 3 (2.4-3.6) Mya, and the primary split within the P. troglodytes complex 1.6 (1.3-2.0) Mya. The analyses suggest that the split between Gorilla and Pan/Homo occurred 8.4 (7.3-9.4) Mya. They also suggest that Pongo (orangutan) and the lineage leading to gorillas, chimpanzees, and humans diverged 18.1 (16.5-19.6) Mya. The present analysis is independent of the hominid paleontological record and inferential morphological interpretations and thus is a novel approach to the lower-limit dating of recent divergences.

Animals↗

PubMed1993

Generation of VNTRs and heteroplasmy by sequence turnover in the mitochondrial control region of two elephant seal species.

We describe an unusual repetitive DNA region located in the 3' end of the light (L)-strand in the mitochondrial control region of two elephant seal species. The array of tandem repeats shows both VNTR (variable-number tandem repeat) and sequence variation and is absent from 12 compared mammalian species, except for the occurrence in the same location of a distinct repetitive region in rabbit mtDNA and a similar repeat in the harbor seal. The sequence composition and arrangement of the repeats differ considerably between the northern elephant seal (Mirounga angustirostris) and the southern species (M. leonina) despite an estimated divergence time of 1 MY (based on an mtDNA-RNA gene and the nonrepetitive control region). Analysis of repeat sequence relationships within and between species indicate that divergence in sequence and structure of repeats has involved both slippage-like and unequal crossingover processes of turnover, generating very high levels of divergence and heteroplasmy.

Animals↗

PubMed1996

Energetics of lactation in harp seals (Phoca groenlandica) from the Gulf of St. Lawrence, Canada.

This study reports the findings of an integrated, comprehensive analysis of lactation energetics in harp seals conducted using longitudinal measurements of mass, body composition and milk composition from mother-pup pairs in conjunction with water flux measurements in pups. The nursing period of harp seals is a short, intense and relatively efficient period of energy transfer from mothers to pups. The average daily milk intake for pups was 3.65 +/- 0.24 kg which is equivalent to 79.5 MJ of energy. Eighty-one per cent of the energy received in the milk was metabolisable and 66% of the energy was stored by the pups as body tissue. The field metabolic rate of pups was 3.9 +/- 0.4 time basal metabolic rate. The pups were growing at a rate of 2.2 kg per day during the nursing period. The distribution of this mass gain varied in terms of tissue composition, depending on the age of the pups, but over the whole nursing period approximately half of the tissue was stored as fat. Harp seal mothers lost an average of 3.1 kg per day during lactation which was composed of 37% water, 50% fat, 11% protein and 2% ash. Mothers spent half of their time during the lactation period actively diving and only one-third of their time on the surface of the ice. Milk compositional changes followed the normal phocid pattern with increasing fat content and decreasing water content as lactation progressed. The mean mass transfer efficiency was 73%. However, this value cannot be used without qualification because female harp seals in this study fed to varying degrees, consuming an estimated 0-4.8 kg of fish per day. Feeding does not appear to be required in order to achieve the energy requirements for lactation, given the energy stores possessed by females, and some females do fast through the entire period so feeding may be considered opportunistic in nature.

Animals↗

PubMed1996

Influence of triacylglycerol structure and fatty acid profile of dietary fats on milk triacylglycerols in the rat. A two-generation study.

We investigated the influence of dietary fatty acid profile and triacylglycerol structure on the fatty acid profile and triacylglycerol structure of milk lipids in two generations of rats. Three groups of rats received diets containing 20% fat of which approximately 20% was n-3 fatty acids located in different positions of the triacylglycerol: a fish oil-based diet [docosahexaenoic acid (22:6n-3) predominantly in the sn-2 position], a seal oil-based diet (22:6n-3) predominantly in the sn-1/sn-3 position, or a plant oil-based diet [alpha-linolenic acid (18:3n-3) distributed evenly between the three positions]. This design allowed us to investigate (i) the effect of the triacylglycerol structure of the dietary fat; (ii) the effect of receiving the n-3 fatty acids as long-chain derivatives or as the precursor, 18:3n-3; and (ii) the long-term effects over two generations. The fatty acid profiles of the milk lipids largely reflected the diets, but in the second generation, the level of medium-chain fatty acids was higher (P < 0.05) in the milk from rats fed the fish oil diet (24%) compared with the other dietary groups (15 and 18%). This suggests an increased endogenous synthesis of fatty acids in the mammary glands of the fish oil-fed rats. The levels of long-chain n-3 fatty acids in milk were higher (P < 0.05) in rats fed marine oils (8-12%) compared with rats fed vegetable oil (1%) in both generations. The level of long-chain n-3 fatty acids was significantly higher in the milk from the fish oil-fed rats (12.3%) compared to the seal- oil fed rats (8.0%) in the first generation, but not in the second generation (8.9 vs. 9.1%). The general structure of milk triacylglycerols was maintained in the three experimental groups with 16:0 acylated in the sn-2 position and 18:1 in the sn-1/sn-3 positions. The triacylglycerol structure of mammalian milk appears to be conserved even during extreme dietary manipulation over two generations and an extensive enrichment with long-chain n-3 polyunsaturated fatty acids requires their presence in the diet.

Animals↗

PubMed1996

Effects of dietary triacylglycerol structure on triacylglycerols of resultant chylomicrons from fish oil- and seal oil-fed rats.

We investigated the influence of the intramolecular fatty acid distribution of dietary triacyl-sn-glycerols (TAG) rich in n-3 polyunsaturated fatty acids (PUFA) on the structure of chylomicron TAG. Fish oil and seal oil, comparable in fatty acid compositions but with different contents of major n-3 PUFA esterified at the sn-2 position (20:5n-3, 46.6%, and 5.3%; 22:6n-3, 75.5%, and 3.8%, respectively), were fed to rats. Mesenteric lymph was collected and the chylomicrons were isolated by ultracentrifugation. The fatty acid composition of chylomicrons largely reflected the fatty acid composition of the oils administered. The intramolecular fatty acid distributions of the TAG fed were reflected in the chylomicron TAG as the fraction of the total contents observed in the sn-2 position of 20:5n-3 were 23.6 and 13.3%, and of 22:6n-3 were 30.6 and 5.4% for resultant chylomicrons following fish oil and seal oil administration, respectively. Thus, after seal oil administration, significant higher load of n-3 PUFA was esterified in the sn-1,3 positions of chylomicron TAG compared with fish oil administration (P < 0.05).

Animals↗

PubMed1982

Positional distribution of fatty acids in triglycerides from milk of several species of mammals.

Milk triglycerides from the echidna, koala, Tammar wallaby, guinea pig, dog, cat, Weddell seal, horse, pig and cow were subjected to fatty acid and stereospecific analysis to determine the positional distribution of the fatty acids in the triglycerides. The samples presented a wide range of fatty acids, most of which varied in content among species. The compositions of the acids at the 3 positions also varied among species, reflecting the content of these acids in the triglycerides. However, there was a general similarity in fatty acid positional distribution patterns for all the species with the exception of the echidna. The echidna exhibited a completely different fatty acid positional distribution pattern. The saturated acids were preferentialy esterified at the sn-1-position whereas the unsaturated acids were selectively esterified at the sn-2-position. The triglyceride carbon number distribution of milk from the above species (with the exception of the Weddell seal) was determined by gas liquid chromatography and compared to that predicted by the 1-random-2-random-3-random fatty acid distribution hypothesis. Agreement was excellent between observed and predicted composition for echidna, koala, Tammar wallaby, guinea pig and pig milk, and agreement was reasonable for dog, cat, horse and cow milk. Results are discussed in relation to biochemical mechanisms.

Animals↗

PubMed1992

Positional specificity of gastric hydrolysis of long-chain n-3 polyunsaturated fatty acids of seal milk triglycerides.

Long-chain n-3 polyunsaturated fatty acids (n-3 PUFA) of marine oils are important dietary components for both infants and adults, and are incorporated into milks following maternal dietary intake. However, little is known about the hydrolysis of these PUFA from milk triglycerides (TG) by lipases in suckling young. Seals, like humans, possess gastric lipase; however, the milk lipids of seals and sea lions are almost devoid of the readily hydrolyzable medium-chain fatty acids, and are characterized by a large percentage (10-30%) of n-3 PUFA. Gastric hydrolysis of milk lipids was studied in vivo in suckling pups of three species (the California sea lion, the harp seal and the hooded seal) in order to elucidate the actions and specificity of gastric lipases on milk TG in relation to fatty acid composition and TG structure. Regardless of milk fat content (31-61% fat) or extent of gastric hydrolysis (10-56%), the same fatty acids were preferentially released in all three species, as determined by their relative enrichment in the free fatty acid (FFA) fraction. In addition to 16:1 and 18:0, these were the PUFA of 18 carbons and longer, except for 22:6n-3. Levels of 20:5n-3 were most notably enriched in FFA, at up to five times that found in the TG. Although 22:6n-3 was apparently also released from the TG (reduced in the diglyceride), it was also notably reduced in FFA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

Effect of marine oils supplementation on coagulation and cellular activation in whole blood.

A study was performed to explore the effects of supplemental intake of various marine oils known to be part of the Eskimo diet. Healthy men and women (134) were randomly selected to consume 15 mL/d of oil from blubber of seal, cod liver, seal/cod liver, blubber of Minke whale, or no oil for ten weeks. Total cholesterol was unchanged in the oil groups, whereas high density lipoprotein cholesterol increased 7% in the seal/cod liver oil (CLO) group (P < 0.05) and 11% in the whale oil group (P < 0.005). Triacylglycerol was significantly reduced in the CLO group only. The concentration of prothrombin fragment 1 + 2 was reduced 25% (P < 0.05) after whale oil supplementation. No change in fibrinogen or factor VIIc was detected. Tumor necrosis factor generation in lipopolysaccharide (LPS)-stimulated blood was 30% reduced after whale oil (P < 0.05), but was unaffected by intake of seal or CLO. The LPS-induced tissue factor activity in monocytes was reduced to a significant degree only in the seal/CLO group (34%) and whale oil group (35%) (P < 0.05). The most dramatic change in thromboxane B2 in LPS-stimulated blood was seen after whale oil intake with 44% reduction (P < 0.01). Supplementation of a regular diet with a combination of seal oil and CLO and especially with whale oil seems to have beneficial effects on several products thought to be associated with cardiovascular and thrombotic diseases.

Adolescent↗

PubMed1994

The lipid composition of selected tissues from a Mediterranean monk seal, Monachus monachus.

The lipid composition of blubber, brain, muscle and heart from a Mediterranean monk seal Monachus monachus (an endangered species) were examined to allow comparisons with more common species of seals. Only neutral lipids (mainly triacylglycerols) were detectable in the blubber lipids, whereas polar lipids predominated in the heart and in the brain. Neutral and polar lipids comprised almost equal proportions in both liver and muscle. Choline glycerophospholipids (CGP) were the major polar lipids, followed by ethanolamine glycerophospholipids (EGP) in the liver, heart and muscle. Cerebrosides accounted for 28.8% of the brain lipids. All lipid classes of the liver contained high levels (31-47%) of polyunsaturated fatty acids (PUFA), with the exception of phosphatidylserine. The total proportion of n-6 PUFA exceeded that of n-3 PUFA in all lipid classes of the liver, due mainly to the high levels of 20:4n-6. The highest level of 20:4n-6 occurred in phosphatidylinositol, where it comprised 32.4% of the total fatty acids. The CGP and EGP of the brain contained lower levels of PUFA than those of the liver, muscle and heart. Alkenyl ethers accounted for 35.8% of the total long-chain moieties in brain EGP. The fatty acid composition of blubber triacylglycerols differed from those of the lipid classes from other tissues in that it had a very low ratio of n-6 to n-3 PUFA (0.3) as a result of a lower content of 20:4n-6.

Adipose Tissue↗

PubMed1995

Very long chain polyunsaturated fatty acids in the blubber of ringed seals (Phoca hispida sp.) from Lake Saimaa, Lake Ladoga, the Baltic Sea, and Spitsbergen.

Blubbers of four ringed seal subspecies from Lake Saimaa, Lake Ladoga, the Baltic Sea, and Spitsbergen were analyzed for very long chain polyunsaturated fatty acids (VLCPUFA; > C22) using gas-liquid chromatography and gas chromatography/mass spectrometry. The VLCPUFA of the blubber oils were mainly n-3 polyunsaturated fatty acids--23:5n-3, 24:3n-3, 24:4n-3, 24:5n-3, 24:6n-3, 26:5n-3, 26:6n-3, and 28:7n-3. The largest VLCPUFA components in all populations were 24:5n-3 (0.1-0.2 wt% of total fatty acids) and 24:6n-3 (0.1%), but 24:4n-3 (0.1%) was also prominent in the Baltic specimens. The blubber oils of the freshwater species contained considerably more 24:4n-6 and 24:5n-6 than the blubbers of the marine species. The differences among the VLCPUFA in these subspecies appear to be mainly due to different dietary VLCPUFA.

Adipose Tissue↗

PubMed1990

Distributional pattern of zinc, cadmium, mercury, and selenium in livers of hooded seal (Cystophora cristata).

The liver of Hooded Seal (Cystophora cristata) consists of six lobes of unequal sizes. Extensive sampling by means of cutout samples covering the depth horizon 2-30 mm below liver surface indicates that the liver may be considered homogeneous as to concentrations of zinc, cadmium, mercury, and selenium (residuals of overall mean compatible with normality, the all-organ variance negligibly in excess of within-lobe variance). Mercury and selenium are present in equimolar concentrations. Cutout samples have mercury and selenium concentrations respectively c. 17 and 8% (dry weight basis) above those of homogenates of the same lobe. The apparent dilution of mercury and selenium is tentatively attributed to coarse blood vessels and bile ducts abundantly present in the homogenate but almost absent from the cutouts.

Animals↗

PubMedDate not supplied

Alaskan marine mammal tissue archival project.

A project to establish an archive of Alaskan marine mammal tissues was conceived in 1987 to be a part of the National Biomonitoring Specimen Bank (NBSB). Protocols and field collection of marine mammals, long-term storage, and analysis are summarized in this paper. Instrumental neutron activation analysis has been used for an initial evaluation of trace element content in samples of northern fur seal (Callorhinus ursinus) from the Pribilof Islands. The findings agree with previously observed trace element levels in northern fur seals. The archived specimens can be used in future studies when comparison of past and present pollution levels are needed.

Alaska↗

PubMed2000

Assessing sequence variation in the internal transcribed spacers of ribosomal DNA within and among members of the Contracaecum osculatum complex (Nematoda: Ascaridoidea: Anisakidae).

The anisakid nematodes of seals from different geographical origins, previously identified as Contracaecum osculatum A, C. osculatum B, C. osculatum C, C. osculatum D, C. osculatulm E and C. osculatum baicalensis by multilocus enzyme electrophoresis, were characterised using a DNA approach. The first and second internal transcribed spacers (ITS-1, ITS-2) of ribosomal DNA (rDNA) were individually amplified by polymerase chain reaction (PCR) and analysed by single-strand conformation polymorphism (SSCP) and sequencing. SSCP analyses allowed the unequivocal differentiation of all taxa except C. osculatum D from C. osculatum E. While C. osculatum D and C. osculatum E had identical ITS sequences, each of the other four taxa had distinct sequences, with interspecific differences ranging from 0.3% to 2.3%. C. osculatum C was genetically the most distinct taxon with respect to all other members of the species complex.

Animals↗

PubMed1998

Ecology of host parasite relationships in the Baltic Sea.

The Baltic Sea is one of the greatest brackish waters, and for 7000 years it has been affected by the influx of haline waters from the North Sea. Many marine and some fresh water organisms have adapted to its lower salinity. Some organisms, referred to as genuine brackish water species, predominate over their near relatives in this environment. All these elements are also present among parasites, which differ in the degree of specialization to their hosts. Analyses of parasite communities, especially those of small fish hosts, reveal characteristics which differ from communities in the marine milieu: (a) suspension of specificity, (b) new hosts, (c) reduction in the number of hosts in life cycles, and (d) adaptation to genuine brackish water hosts. The view of the Baltic Sea as a species-poor but balanced ecosystem is also valid for parasites. The Baltic Sea is endangered by the high level of eutrophication, as the organisms are not adapted to its consequences. The study of parasite communities reveals such threatening conditions for the respective environments.

Animals↗

PubMed2000

Salinity discrimination in harbour seals: a sensory basis for spatial orientation in the marine environment?

Salinity variations can be considered as a potential source of information for orientation in the marine environment. To use this kind of environmental information marine animals must be able to detect these salinity differences. Therefore we determined salinity-difference thresholds of two harbour seals for the discrimination of seawater solutions as a function of the salinity level (15-35@1000) and compared them with the thresholds of human subjects. Whereas in humans thresholds increased with increasing salinity level, thresholds of seals decreased with increasing salinity level. Both seals achieved best sensitivity at 30/1000 salinity, where they detected a salinity difference < or = 4%. These data indicate that the ability of seals to detect salinity differences of seawater is well tuned to the natural occurrence of this environmental information. Their high gustatory resolving power for differences in seawater salinity is suggested to meet the basic requirements for chemosensory orientation of seals in the marine habitat.

Animals↗

PubMed2002

Elevated concentrations of trace elements in Caspian seals (Phoca caspica) found stranded during the mass mortality events in 2000.

Concentrations of V, Mn, Fe, Cr, Co, Cu, Zn, As, Se, Mo, Ag, Cd, Tl, Hg, Pb, and organic mercury (Org-Hg) were determined in liver, kidney, and muscle of healthy Caspian seals ( Phoca caspica) collected in 1998. These concentrations were compared with those of seals infected with canine distemper virus (CDV) found stranded along the coastal areas in 2000. Concentrations of toxic elements (As, Ag, Cd, Tl, Hg, Pb, and Org-Hg) in Caspian seals stranded in 2000 were comparable or lower than those of samples collected in 1998 and in other pinnipeds. Thus it may be inferred that these elements were not the causative agents in the deaths of the seals. In contrast, concentrations of Zn and Fe were much higher in diseased Caspian seals than those in other pinnipeds. Zinc concentrations in all tissues of Caspian seals also increased during 1993-2000. Furthermore, negative correlations were found between blubber thickness and hepatic and renal Zn concentrations. These results imply the disturbance in homeostatic control and nutritional status of essential elements in Caspian seals stranded in 2000.

Animals↗