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PubMed2006

Metabolism of dietary cetoleic acid (22:1n-11) in mink (Mustela vison) and gray seals (Halichoerus grypus) studied using radiolabeled fatty acids.

Cetoleic acid (22:1n-11) is a good indicator of diet in marine predators and has proven to be an important fatty acid (FA) when using adipose tissue FA composition to study diet in marine mammals and seabirds. Feeding studies have shown that 22:1 isomers are predictably underrepresented in adipose tissue relative to diet, implying that metabolism within the predator strongly influences the relationship between the level of these FAs in diet and adipose tissue. Fully understanding such metabolic processes for individual FAs is important for the quantitative estimation of predator diets. We employed a dual-label radioisotope tracer technique to investigate the potential modification of 22:1n-11 and its recovery in the blubber of gray seals (Halichoerus grypus) and in the adipose tissue and liver of mink (Mustela vison), a smaller model carnivore also accustomed to fish-based diets. In both seals and mink, (3)H radioactivity was found in the chain-shortened products of 22:1n-11, with 18:1 being the dominant product. We also found (3)H radioactivity in saturated FAs. The distribution patterns of (3)H radioactivity across the FAs isolated from seal blubber and mink subcutaneous adipose tissue were comparable, indicating that mink are a good model for the investigation of lipid metabolism in marine carnivores.

Adipose Tissue↗
PubMedDate not supplied

Temperature effects on the breeding distribution of grey seals (Halichoerus grypus).

The metabolic rates of six female grey seal (Halichoerus grypus) pups were measured during their postweaning fast at air temperatures between -15 degrees and 30 degrees C. The composite of their individual thermal neutral zones extended from a mean lower critical temperature of -7.1 degrees +/- 0.7 degree C to a mean upper critical temperature of 23.0 degrees +/- 0.4 degree C. Within the thermal neutral zone, mean standard metabolic rate of the fasting animals was 1,265 +/- 82 kcal d-1, or about 1.1 times the value predicted for an adult animal of similar body mass (mean mass = 40.9 +/- 1.2 kg). For those grey seal populations that reproduce during winter months in the eastern and western Atlantic and in the Baltic Sea, the lower critical temperature of fasting pups corresponds closely with the coldest mean monthly air temperature at the northern end of their breeding ranges. This observation supports the hypothesis that cold ambient air temperatures limit the northern breeding distribution of grey seals, primarily through their thermoregulatory effects on small, fasting pups before they enter the water.

Animals↗
PubMed2003

Proliferative effects of estradiol, progesterone, and two CB congeners and their metabolites on gray seal (Halichoerus grypus) uterine myocytes in vitro.

Gray seal females living in the Baltic Sea have been found to exhibit a high prevalence of uterine leiomyomas. These animals are also known to accumulate lipid-soluble PCBs in their blubber. PCBs have documented endocrine-disrupting effects; to investigate whether the PCBs could be part of the genesis of uterine smooth muscle tumors in this species, gray seal myometrial cell cultures were exposed to two CBs and their metabolites, as well as to estradiol and progesterone, after which the effects were analyzed in terms of proliferative activity by measurements of BrdU absorbance and protein content. Progesterone was found to have an inhibitory effect, whereas one CB acted as a stimulant on the myometrial cell proliferation. One of the CB metabolites also seemed to have an inhibitory effect, although this could not be statistically verified. These results suggest that some CBs have effects on uterine myometrial cell proliferation in gray seals and, thus, may also take part in the growth regulation of uterine leiomyomas.

Animals↗
PubMed1991

Mycoplasma phocarhinis sp. nov. and Mycoplasma phocacerebrale sp. nov., two new species from harbor seals (Phoca vitulina L.).

A total of 120 mycoplasma strains were recovered from 97 of 265 diseased seals investigated during the seal epidemic in the North Sea and in the Baltic Sea in 1988. Mycoplasmas were isolated from the respiratory tracts (including lungs), hearts, brains, and eyes of the seals. Thirty strains were filter cloned and investigated for their morphological, biochemical, and serological characteristics compared with the characteristics of previously described species. The results of an indirect immunofluorescence test, a growth inhibition test, and an immunobinding assay showed that these strains belong to two new species, for which the names Mycoplasma phocarhinis and Mycoplasma phocacerebrale are proposed. M. phocarhinis (17 strains) did not ferment glucose or hydrolyze arginine but did reduce tetrazolium chloride and potassium tellurite and produced films and spots. M. phocacerebrale (13 strains) metabolized arginine but not glucose and produced phosphatase but did not reduce tetrazolium chloride and potassium tellurite. Both species lysed sheep erythrocytes but did not absorb sheep or guinea pig erythrocytes. The type strain of M. phocarhinis is strain 852 (= ATCC 49639), and the type strain of M. phocacerebrale is strain 1049 (= ATCC 49640).

Animals↗
PubMed2005

Streptococcus marimammalium sp. nov., isolated from seals.

Two strains of an unidentified, Gram-positive, catalase-negative, chain-forming, coccus-shaped organism recovered from seals were characterized using phenotypic and molecular taxonomic methods. Based on morphological and biochemical criteria the strains were tentatively identified as streptococci but they did not appear to correspond to any recognized species of the genus Streptococcus. Comparative 16S rRNA gene sequencing studies showed that the strains were closely related to each other and confirmed their placement in the genus Streptococcus. Sequence divergence values of >5 % with reference streptococcal species demonstrated the organisms from seals represent a novel species. SDS-PAGE analysis of whole-cell proteins confirmed that the two organisms were closely related to each other but were different from all currently defined streptococcal species. Based on biochemical criteria, molecular chemical and molecular genetic evidence, it is proposed that the unknown isolates from seals be assigned to a novel species of the genus Streptococcus, Streptococcus marimammalium sp. nov. The type strain is M54/01/1T (=CCUG 48494T=CIP 108309T).

Animals↗
PubMed2004

Major histocompatibility complex variation at three class II loci in the northern elephant seal.

Northern elephant seals were hunted to near extinction in the 19th century, yet have recovered remarkably and now number around 175,000. We surveyed 110 seals for single-strand conformation polymorphism (SSCP) and sequence variation at three major histocompatibility (MHC) class II loci (DQA, DQB and DRB) to evaluate the genetic consequences of the population bottleneck at these loci vs. other well-studied genes. We found very few alleles at each MHC locus, significant variation among breeding sites for the DQA locus, and linkage disequilibrium between the DQB and DRB loci. Northern elephant seals are evidently inbred, although there is as yet no evidence of correlative reductions in fitness.

Amino Acid Sequence↗
PubMed1986

A fluctuation in plasma melatonin level in the Weddell seal during constant natural light.

Blood was collected over a 24-h period from free-living adult Weddell seals that had been exposed to natural constant daylight for some 12 weeks. The plasma melatonin concentration was low throughout the trial (range of means: 30.8-70.4 pg/ml) with the exception of a 3-h period centered on 1700 h local time, when the plasma level rose to a mean of 131.8 pg/ml. The pineal gland of the Weddell seal is thus capable of transient bouts of activity during constant and bright daylight, a situation usually inhibitory to the function of the gland. It is suggested that circadian fluctuations in the intensity of constant light entrain variation in the pineal gland functioning of this seal during summer.

Animals↗
PubMed1990

The pineal gland in newborn southern elephant seals, Mirounga leonina.

In the newborn southern elephant seal the pineal gland is very large, and both pineal and plasma melatonin concentration is elevated. The pineal gland was investigated during the first 24 h, and up to 20 days of age, in elephant seal pups. A primary aim of this investigation was to determine whether there are obvious ultrastructural characteristics of pinealocytes that are exhibiting extraordinarily high levels of activity. Blood and pineal glands were collected from thirty seven pups of known age which were sampled at random from early September to early November (1985) at Macquarie Island. The pineal gland is large (mean weight, 4.71 +/- 0.35 gm, range 1-9.3 gm) and actively secreting melatonin at birth. Melatonin concentrations were extremely variable, yet very high in pups during the first 24 h post-partum. Mean melatonin plasma concentration for pups 0-24 h was 17632.8 +/- 5723.8 pmol/l (4090.8 +/- 1327.9 pg/ml), ranging from 126 pmol/l (29 pg/ml) to 297000 pmol/l (68904 pg/ml). Electron microscopic examination did not reveal any marked changes in pinealocyte ultrastructure suggestive of increased secretory activity during this period. The large and extremely active pineal gland in newborn southern elephant seal suggests that it is actively involved in thermoregulation.

Aging↗
PubMed1975

Differential effects of temperature on activity of LDH from seal and sheep skin.

The homeothermic seal possesses a heterothermic skin, while the skin of the sheep behaves as a truly homeothermic tissue. A new method for skin homogenization is described. The effect of temperature on the catalytic behaviour of seal and sheep skin LDH has been investigated by fluorimetric activity measurements, with results presented as Arrhenius plots. The seal skin enzyme had ten times higher activity at low temperatures as compared to the sheep skin. The mechanisms responsible for this different behaviour are discussed.

Animals↗
PubMed1978

Aspects of temperature regulation in harp seal pups evaluated by in vivo experiments and computer simulations.

Temperature regulation in harp seal pups (Pagophilus groenlandicus) has been studied by in vivo measurements of oxygen consumption, body temperatures and in vitro determinations of the thermal values of a fur sample. The experimental animals were restrained and exposed to natural wheather conditions. Solar irradiance above 600 W/m (global radiation) caused hyperthermia. Computer simulations based on the thermal values of the fur indicated that heat dissipation from primarily the limbs is a prerequisite for avoiding hyperthermia under natural weather conditions. Further simulations showed that the lower critical temperature of a lean newborn harp seal pup with standard metabolism is only--1 degree C while it is depressed to--59 degree C as the pup grows, aquire a 10 cm thick layer of blubber and the metabolism increases to 1.5 times standard. High metabolism and tolerance to low deep body temperatures (35 degree C) seems a prerequisite for thermal balance in the harp seal pup under cold conditions.

Animals↗
PubMed1983

Cardiac output and its distribution through capillaries and A-V shunts in diving seals.

Regional blood flow and cardiac output were determined by distribution of radioactive microspheres injected via catheter into the left ventricle during experimental diving and recovery in juvenile spotted seals (Phoca vitulina largha) and grey seals (Halichoerus grypus). Cardiac output was 9.7 L/min before diving, declined 90% during submersion and increased to 12.1 L/min after 40 s of recovery. Left ventricular myocardial perfusion declined from 179 +/- 24 (21) to 25 +/- 2 (6) ml/min . 100 g at 2 min submersion, and measured 23 +/- 3 (8) after 10 min of submersion. Cerebral cortical flow was reduced from a pre-dive value of 115 +/- 3 (15) to 40 +/- 5 (3) and 49 +/- 6 (3) at 2 and 5 min of diving, respectively, but increased to 253 +/- 14 (4) ml/min . 100 g at 10 min along with elevated PCO2 (84 torr) and lowered pH (7.10) in arterial blood. It remained at that level in recovery. Brain stem perfusion after 10 min submersion was still identical with control, but increased to 275% of control in recovery. Adrenal flow decreased to 34 and 27% of control at 2 and 5 min of diving, respectively. Recovery flow after 10 min of diving was 200% of control. Liver, kidney, fat, skin, and stomach were ischemic throughout the dive. Recovery flow increased slowly in these tissues. Skeletal muscle (M. psoas) was perfused at a low rate. (3 ml/min . 100 g) pre-dive and was ischemic during diving. Recovery muscle perfusion was variable at different sites (from 5 to 105 ml/min . 100 g). Pre-dive pulmonary capillary perfusion was 58 +/- 8 (9) ml/min . 100 g, decreased to 7 +/- 0 (3) ml/min . 100 g min of submersion, and had increased to 50% of pre-dive value after 40 s of recovery from a 10 min dive. Conclusions are: (1) previous information from implanted flow transducers was confirmed, (2) detailed data for discrete tissues elaborate the concept of selective redistribution of cardiac output in diving seals, (3) non-uniform reperfusion contributes to the maintenance of arterial pressure during recovery, and (4) substantial A-V shunting of cardiac output took place in the first 2-5 min of the dive, when total capillary/nutritive flow was low. Late in the dive, however, CO was routed through systemic capillaries mainly in the cerebral circulation and less than 15% through A-V shunts.

Adrenal Glands↗
PubMed1990

Depressed metabolism and low protein catabolism in fasting grey seal pups.

Grey seal pups (Halichoerus grypus) were collected at the time of weaning (mid-October) and fasted for 52 days at thermoneutrality in separate cages. Body weight decreased exponentially, while metabolic rate dropped 45% from an average of 2.95 +/- 0.15 (SEM) W kg-1 at day 2 of fasting to a stable level of 1.62 +/- 0.06 (SEM) W kg-1 from day 10 to day 47 of fasting. Respiratory quotient was low, indicating extensive catabolism of triglycerides, while plasma cortisol was fairly stable at 110 +/- 8 (SEM) nmol l-1 throughout the fasting period. Daily urinary output decreased from 236 +/- 20 (SEM) ml day-1 at day 2 to a stable value of 87 +/- 6 (SEM) ml day-1 between days 8 and 50 of fasting. The urine was analysed for urea, uric acid, creatinine, ammonia, total nitrogen and osmolality. Urea was always the principal excretory end-product, amounting to between 70 and 80% of the total excreted nitrogen. The urine was moderately concentrated (range 770-1300 mosmol kg-1). Total excreted urinary nitrogen decreased by 68% from 3.7 +/- 0.7 (SEM) g day-1 to 1.2 +/- 0.4 (SEM) g day-1 between days 2 and 50. The urinary nitrogen was used to calculate the daily amount of protein being oxidized and its energy content was compared with the measured basal metabolic rate of individual animals. Approximately 6% of the energy expended by grey seal pups during the post-weaning fast is derived from oxidation of protein. It is concluded that a rapid depression of basal metabolic rate and extensive blubber catabolism enable grey seal pups to endure prolonged periods of fasting without any apparent signs of discomfort or stress.

Animals↗
PubMed1991

Glucose and ketone body turnover in fasting grey seal pups.

Concentration and metabolic replacement (turnover) rate of glucose and ketone bodies were determined at intervals during a 52 day postweaning fast in five grey seal (Halichoerus grypus) pups, using bolus injections of radiotracers. Blood glucose was maintained at a high level throughout the fast, while beta-hydroxybutyrate increased 26 times from day 3 to day 37, whereafter it by and large was maintained. Glucose replacement rate decreased to 56% of the day 9 value at day 37 and dropped further to only 32% of the day 9 level at day 52 in two seals, while in another 2 seals it increased at this late stage. The average ketone body replacement rate ranged between 8.6 and 13.8 mumols min-1 kg-1, but did not change significantly (P greater than 0.05) during the fasting period. These results suggest a reduced gluconeogenesis from protein and increased production of ketone bodies, which may in part replace glucose as energy source during fasting.

Animals↗
PubMed1993

Relationship between blood buffering properties, erythrocyte pH and water content, in gray seals (Halichoerus grypus).

The separated plasma of gray seals (Halichoerus grypus) has an unusually high non-bicarbonate buffering capacity (beta NB = d[HCO3-]/dpH = -21 Slykes; Slyke = mmol l-1 pH unit-1). To examine whether this represents a trait of mammalian carnivora, or is related instead to deep diving, we examined blood from dog and killer whale, respectively. The beta NB of separated plasma of dog was typically low (-4 to -8 Slykes), as in other mammals, whereas that of the whale (-13.5 Slykes), while significantly higher than dog, was not nearly as high as in seal. As one would theoretically predict of a blood system with exceptionally high extracellular buffering and functional anion exchange across the erythrocyte membrane, there was little difference in the buffer slope between true plasma and whole blood of seal. This appears to be a novel pattern of CO2 carriage in mammals. Erythrocyte ion concentrations were similar to other mammalian carnivora, with intracellular sodium concentration being high and potassium low. The red cell water content was unaffected by changes in oxygen saturation and tended to decrease when extracellular pH decreased below 7.4. Apart from the comparatively elevated Bohr factor, -0.518 as a function of extracellular pH and -0.550 as a function of red blood cell pH, the blood oxygen binding properties were similar to terrestrial mammals of similar size.

Animals↗
PubMed1977

Disease and injury in the southern elephant seal.

Disease and injury was recorded in 170 tagged soughern elephant seals (Mirounga leonina) on the Antarctic continent. Trauma due to interspecific predation was the most common disorder. No small seals were observed with lesions attributable to this in the Antarctic population. This finding differs from data recorded in a sub-Antarctic (Macquarie Island) population where seals of all class sizes exhibit lesions due to interspecific trauma. No external parasites were observed in the Antarctic population.

Animal Diseases↗
PubMed2002

Blood values of juvenile northern elephant seals (Mirounga angustirostris) obtained using a portable clinical analyzer.

BACKGROUND: Sick, injured, or orphaned juvenile northern elephant seals (Mirounga angustisrostris) treated at rehabilitation centers frequently present with abnormalities in blood sodium, potassium, chloride, BUN, and glucose concentrations, and HCT. These abnormalities could be detected rapidly using a portable blood analyzer, but results with this analysis method do not necessarily equate with those obtained using other techniques. OBJECTIVE: The objective of this study was to better assess the clinical relevance of values obtained from a portable analyzer and to compare the results with values obtained using more common methods of analysis. METHODS: Heparinized whole blood samples were collected from 20 rehabilitated juvenile northern elephant seals. A portable clinical analyzer (i-STAT, i-STAT Corp, East Windsor, NJ, USA) was used to establish baseline values. Serum biochemical values were obtained using an automated chemical analyzer (Olympus AU5200, Olympus America, Melville, NY, USA). HCT was determined using EDTA whole blood and a cell counter. RESULTS: Using the portable analyzer, mean (minimum-maximum) values were obtained for sodium, 143 (132-146) mmol/L; potassium, 4.4 (3.9-5.8) mmol/L; chloride, 106 (101-109) mmol/L; BUN, 1.8 (1.1-2.4) mmol/L; glucose, 7.55 (5.99-8.49) mmol/L; and HCT, 0.55 (0.52-0.61) L/L. Average differences between methods were small for potassium (-0.45 mmol/L), BUN (0.1 mmol/L), and HCT (0.037 L/L) but were large for sodium (-6.8 mmol/L), chloride (-6.4 mmol/L), and glucose (-0.56 mmol/L). CONCLUSIONS: These results suggest that the i-STAT portable analyzer could be useful for clinically assessing juvenile elephant seals. However, when making medical decisions, the clinician should be aware of differences associated with various analyzers and sample types.

Animals↗
PubMed2003

Measuring hearing in the harbor seal (Phoca vitulina): comparison of behavioral and auditory brainstem response techniques.

Auditory brainstem response (ABR) and standard behavioral methods were compared by measuring in-air audiograms for an adult female harbor seal (Phoca vitulina). Behavioral audiograms were obtained using two techniques: the method of constant stimuli and the staircase method. Sensitivity was tested from 0.250 to 30 kHz. The seal showed good sensitivity from 6 to 12 kHz [best sensitivity 8.1 dB (re 20 microPa2 x s) RMS at 8 kHz]. The staircase method yielded thresholds that were lower by 10 dB on average than the method of constant stimuli. ABRs were recorded at 2, 4, 8, 16, and 22 kHz and showed a similar best range (8-16 kHz). ABR thresholds averaged 5.7 dB higher than behavioral thresholds at 2, 4, and 8 kHz. ABRs were at least 7 dB lower at 16 kHz, and approximately 3 dB higher at 22 kHz. The better sensitivity of ABRs at higher frequencies could have reflected differences in the seal's behavior during ABR testing and/or bandwidth characteristics of test stimuli. These results agree with comparisons of ABR and behavioral methods performed in other recent studies and indicate that ABR methods represent a good alternative for estimating hearing range and sensitivity in pinnipeds, particularly when time is a critical factor and animals are untrained.

Animals↗
PubMed2003

The effect of a low-frequency sound source (acoustic thermometry of the ocean climate) on the diving behavior of juvenile northern elephant seals, Mirounga angustirostris.

Changes in the diving behavior of individual free-ranging juvenile northern elephant seals, Mirounga angustirostris, exposed to the acoustic thermometry of the ocean climate (ATOC) sound source were examined using data loggers. Data loggers were attached to the animals and measured swim speed, maximum depth of dive, dive duration, surface interval, descent and ascent rate, and descent and ascent angle along with sound pressure level (SPL). The ATOC sound source was at a depth of 939 m and transmitted at 195 dB re: 1 microPa at 1 m centered at 75 Hz with a 37.5-Hz bandwidth. Sound pressure levels (SPL) measured at the seal during transmissions averaged 128 dB and ranged from 118 to 137 dB re: 1 microPa for the 60-90 Hz band, in comparison to ambient levels of 87-107 dB within this band. In no case did an animal end its dive or show any other obvious change in behavior upon exposure to the ATOC sound. Subtle changes in diving behavior were detected, however. During exposure, deviations in descent rate were greater than 1 s.d. of the control mean in 9 of 14 seals. Dive depth increased and descent velocity increased in three animals, ascent velocity decreased in two animals, ascent rate increased in one animal and decreased in another, and dive duration decreased in only one animal. There was a highly significant positive correlation between SPL and descent rate. The biological significance of these subtle changes is likely to be minimal. This is the first study to quantify behavioral responses of an animal underwater with simultaneous measurements of SPL of anthropogenic sounds recorded at the animal.

Acoustics↗