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At least 847 records · Page 47Linked to original sources
PubMed1995

Short term fasting does not aggravate immunosuppression in harbour seals (Phoca vitulina) with high body burdens of organochlorines.

Two groups of 11 harbour seals (Phoca vitulina) with different body burdens of organochlorines were subjected to an experimental 15-day fasting period, during which they lost an average 16.5% of their body weights. Blood levels of the most persistent organochlorines showed an approximate twofold increase, while levels of aryl hydrocarbon receptor-binding organochlorines remained largely unaffected. Few differences in immunological parameters were observed between the two dietary groups. Numbers of circulating lymphocytes dropped to about 65% of the initial values and NK cell activity showed a slight increase in both groups. Mitogen- and antigen-induced lymphoproliferative responses of the Baltic group of seals remained within normal ranges. These results suggest that relatively short-term fasting periods do not present an additional immunotoxicological risk to seals with high body burdens of organochlorines.

Adipose Tissue↗
PubMed1976

Organochlorine and mercury residues in the harp seal (Pagophilus groenlandicus).

Samples of blubber, liver, kidney and brain, obtained from 10 male, 6 female neonatal, and 4 lactating female harp seals (Pagophilus groenlandicus), were analysed for DDT, dieldrin, PCB, and total mercury. Methyl mercury levels in blood were also determined. Biocide deposition was not significantly different in female and male ten day old pups. There were no significant differences in biocide levels in the liver of the 14/+ day old males, but in blubber there were significant differences in dieldrin and DDT. There was no clear relationship between biocide levels in the 6-18 year old lactating adults and their pups. Younger adult seals (6 and 7 years) were found to have higher levels of PCB and sigmaDDT levels in their blubber than did older females (10 and 18 years). Wide intraspecific variation was noted in organochlorine and mercury residue levels. Pups taken in 1973 were found to have lower organochlorine residues than pups taken in the same area in 1971. Preliminary investigation indicates that detectable amounts of organochlorine and mercury residues are capable of crossing the placenta in the harp seal.

Adipose Tissue↗
PubMed1984

Pollutants in harp seals (Phoca groenlandica). I. Organochlorines.

Between 1976 and 1978, 248 harp seals were sampled from 5 locations in the Northwest Atlantic and Arctic for organochlorine (OC) residue analysis in tissue. Blood, kidney, brain, muscle and blubber samples were analysed for PCB, DDT, dieldrin, hexachlorobenzene (HCB), and heptachlor epoxide. Levels were generally greatest in blubber tissue. Overall, mean levels of DDT and PCB were greater than those of other OC. A barrier prevented OC compounds from accumulating in the brain to the level one might expect in lipid tissues. Positive correlations were found between 1: DDT and PCB, 2: DDT and dieldrin, and 3: PCB and deildrin. Male harp seals bioaccumulated DDT, PCB, heptachlor epoxide and dieldrin with age. As a group, adult males sampled in the Gulf of St. Lawrence carried the highest concentrations of all OC, except that chlordane did not appear to bioaccumulate and levels of hexachlorobenzene were minimal. Females generally ceased exhibiting significant bioaccumulation once breeding age was reached, due to transplacental and transmammary residue transfer of OC from mother to pup. There were some significant differences in OC levels between locations with DDT: Gulf greater than Front; PCB: Gulf greater than Front; dieldrin: Gulf greater than Front; heptachlor epoxide: Front greater than Gulf. No significant differences were found, however, when northern locations (Grise Fiord, Northwest Greenland, Pangnirtung) were compared to southern (Gulf, Front) on a group basis. The latter is not surprising in view of the harp seals extensive cyclical annual migration between the southern breeding grounds and the High Arctic.

Animals↗
PubMed1984

Pollutants in harp seals (Phoca groenlandica). II. Heavy metals and selenium.

Between 1976 and 1978, 249 harp seals were sampled from five locations in the Northwest Atlantic and Arctic for heavy metal and selenium residue analyses in tissue. Significant loading was apparent only in blood, brain, kidney, liver and muscle. Samples were analysed for mercury (Hg), selenium (Se), copper (Cu), cadmium (Cd) and lead (Pb). The seals carried higher levels of Cd than of the other metals. Residue levels of Cd were highest in kidney tissue; levels of other metals were highest in liver. Both males and females bioaccumulated Cd, Hg and Se. Cd, Hg, Se and Cu residues were detected in tissue from neonatal seals, indicating that transplacental and transmammary transfer of these elements had occurred. Despite the passage of residues from mother to pup, females bore significantly higher levels of Hg and Cd than males. Conversely, levels of Cu, Se or Pb did not appear to differ significantly between sexes. There was considerable individual variation in residue levels. This, coupled with the extensive annual migration undergone by these animals, made it difficult to arrive at definite conclusions regarding geographic accumulation patterns.

Animals↗
PubMed1992

Molecular and serological studies on the recent seal virus epizootics in Europe and Siberia.

The virus epizootics which occurred in seals in both Europe and Siberia during 1987/1988 were caused by two different morbilliviruses, referred to as phocid distemper virus (PDV) 1 and 2, respectively. Molecular and serological studies have shown that the European virus is quite distinct from canine distemper virus (CDV), its closest relative in the morbillivirus group. Analysis of tissues obtained from infected seals from a wide geographical distribution over Northern Europe showed that the infectious agent (PDV 1) was identical in all cases. Nucleotide sequence analysis of one of the virus genes suggested that this virus has evolved away from CDV over a long time period and is most probably an enzootic virus of marine mammals. In contrast, the virus (PDV 2) which caused the deaths of many Siberian seals was indistinguishable, both serologically and at the molecular level, from CDV and must have originated from a land source.

Animals↗
PubMed1992

Tissue concentrations of organochlorine compounds in common seals from the coast of Northern Ireland.

An epizootic of morbillivirus infection killed several hundred common seals (Phoca vitulina) along the coast of Northern Ireland in 1988. Many dead and moribund seals were submitted to the Department of Agriculture for Northern Ireland, Veterinary Research Laboratories for necropsy. Samples of blubber, liver and kidney were collected from these animals (n = 55) for analysis for a wide range of organochlorine pesticides and also total polychlorinated biphenyls (PCBs). The organochlorines found in highest concentrations in blubber were PCBs which were detected in all samples (mean, 26 micrograms g-1 wet wt). sigma DDT (mean, 2.63 micrograms g-1 wet wt) and chlordane (mean, 0.22 micrograms g-1 wet wt) were also present in all samples. Heptachlor including heptachlor epoxide (mean, 0.13 micrograms g-1 wet wt) was present in over 93% of samples. Seventy-four percent of samples contained alpha HCH (mean, 0.035 micrograms g-1 wet wt), 50% contained beta HCH (mean, 0.026 micrograms g-1 wet wt) while gamma HCH (mean, 0.012 micrograms g-1 wet wt) was detected in 46% of samples. The organochlorine concentrations found in this study are at the lower end of the range previously reported for European common seals.

Adipose Tissue↗
PubMed1994

Relative immunocompetence of the newborn harbour seal, Phoca vitulina.

The immune system of many mammalian species is not fully developed at birth, with newborns obtaining temporary immunological protection from maternal antibodies. Little is known of the immune system of the harbour seal, and developmental aspects of its immune system have not been systematically studied. We collected blood and milk samples from nine free-ranging mother-pup pairs throughout the lactation period on Sable Island, Canada, in an effort to characterise developmental aspects of the immune system of this newborn pinniped. Pup lymphocytes responded stronger to the mitogens concanavalin A, phytohaemagglutinin, and pokeweed mitogen than the lymphocytes of their mothers. In contrast to newborn cats and dogs, newborn seal pups developed high specific antibody responses after immunisation with an inactivated rabies vaccine. Circulating levels of total IgG in newborn pups were low (3% of maternal levels), but increased rapidly after colostrum intake (to 65% of maternal levels after 15 days). A similar pattern of increase in pup serum was observed for phocine distemper virus specific antibodies which had been detected in the serum and milk of mothers, suggesting that the transfer of colostral antibodies is an important feature of temporary protection for the pup. We speculate that the relative immunocompetence of the harbour seal at birth reflects an adaptation to its relatively short nursing period and limited maternal care.

Animals↗
PubMed1989

A morbillivirus causing mass mortality in seals.

During an outbreak of a serious apparently infectious disease among harbour seals (Phoca vitulina), which started in the Kattegat area in April 1988 and rapidly spread to the North sea, the Wadden sea and the Baltic sea, greater than 17,000 animals died within a period of eight months. In August 1988 it was realized that the clinical symptoms and pathological lesions were similar to those found in canine distemper: apart from general depression and fever, the animals suffered from severe respiratory, gastrointestinal and central nervous disease and a variety of viral, bacterial and parasitic infections were frequently encountered, suggesting a severe malfunctioning of the immune system. At different expert meetings, held in several of the countries involved, possible explanations for the deaths were not only attributed to an infectious agent, but also to effects of overpopulation and environmental pollution. Seroepizootiological studies and the failure of vaccination experiments suggested that a herpesvirus and a picornavirus, which had been isolated from dead seals at the beginning of the outbreak, were opportunistic infections occurring in animals suffering from another infection rather than being the primary cause of the outbreaks. Serological studies were then extended to other viruses of carnivores, known to cause similar symptoms. Screening of a large panel of seal sera from the Netherlands, Denmark, FRG, Sweden and the UK, collected before and during the outbreak, in a virus neutralization test for the presence of canine distemper virus (CDV) neutralizing antibodies, indicated that CDV or a closely related morbillivirus was the primary cause of the disease outbreak.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Weight loss and catabolic adaptations to starvation in grey seal pups.

Five grey seal pups lost from 18 to 32% of their initial body weight during a 21 day starvation period. Blubber fat mass density was 0.93 +/- 0.03 g/cm3. A considerable loss of blubber fat was recorded, but analysis of the weight loss and body size data indicated that blubber fat was retained for thermoregulatory reasons, particularly in the lean, smaller seals. It is possible that phocid seals during periods of negative energy balance have a higher rate of protein catabolism than normal for terrestrial mammals.

Adaptation, Physiological↗
PubMed1991

Insulation and thermal balance of fasting harp and grey seal pups.

1. Harp and grey seal pups were examined during the post-weaning period to quantify their thermoregulatory abilities and thermal limits. 2. Deep body temperatures of harp seals (37.8 +/- 0.8 degrees C) were not significantly different from those of grey seals (38.9 +/- 0.4 degrees C). 3. As blubber depth declined during the fast, temperature gradients extended increasingly deeper into the muscle layer potentially decreasing heat loss. 4. Blubber conductivity (approximately 0.18 W/m/degrees C) did not vary regionally within an animal, or between animals or species. 5. Calculated lethal cold limits in air were between -85.4 degrees C and -116.1 degrees C, suggesting that fasting, weaned pups can easily cope with temperatures they would normally experience.

Adipose Tissue↗
PubMed1993

Effects of energy mobilization during fasting and lactation on plasma metabolites in the grey seal (Halichoerus grypus).

1. The effects of fasting and lactation on plasma metabolites and insulin as well as morphometric parameters related to the mobilization of energy reserves were investigated in grey seals (Halichoerus grypus) of different ages and sex during the 4 week terrestrial breeding period on Sable Island, NS, Canada. 2. Clear differences in body length and girth between the sexes were already recognizable in juveniles. Fasting and lactation caused a marked decrease in adipose tissue thickness and girth in lactating females. At the same time, there was a considerable increase in body weight, blubber thickness and girth in sucking pups. 3. The level of lipids and free fatty acids were much higher compared to terrestrial species and were clearly affected by lactation and sucking. The onset of lactation caused a marked decrease in total lipids (basically triglycerides). 4. In sucklings, the level of lipids was much higher (mainly triglycerides) than in weaned ones, whereas phospholipids and cholesterol increased with the post-weaning fast. 5. Glucose levels in blood were higher in grey seals of all ages (> 1.2 g/l) than in terrestrial mammals. No obvious differences related to the metabolic changes were observed. 6. Contrary to other species, glucose and glycerol were higher in the blood of the fetus than in the blood of the mother. 7. The high concentrations of glucose and glycerol and the lack of ketone bodies in the blood plasma of adult seals during fasting suggests a possible utilization of acetone for gluconeogenesis.

Aging↗
PubMed1986

The lipid composition of serum lipoproteins in the harbour seal, Phoca vitulina.

The density profile of serum lipoproteins and their lipid composition was studied in 12 adult, female harbour seals. The animals were sampled after an approximate 20 hr fast. The density profile of lipoproteins showed that the harbour seals displayed a distinct VLDL (density less than 1.006 g/ml) and HDL band (density about 1.125 g/ml), but no clear LDL band. There was a rather diffuse population of lipoproteins in the density range of 1.019-1.100 g/ml. Mean serum total cholesterol concentration was 5.7 mmol/l; about 60% of this cholesterol was located in the HDL fraction (density greater than 1.063 g/ml). The fasted seals were found to carry 4% of serum total lipids in chylomicrons. These lipoproteins consisted of 51% of triaclyglycerols (on the basis of total chylomicron lipids). The LDL (defined as heparin-manganese precipitable lipoproteins in VLDL and chylomicron-deficient serum) contained 49% of cholesterol and 43% of phospholipids (on the basis of total LDL lipids). The HDL (defined as heparin-manganese soluble lipoproteins in VLDL and chylomicron-deficient serum) contained 36% of cholesterol and 58% of phospholipids (on the basis of total HDL lipids).

Animals↗
PubMed1988

Characterization of proteins and fatty acid composition in Galapagos fur seal milk. Occurrence of whey and casein protein polymorphisms.

1. Milk proteins of the Galapagos fur seal (Arctocephalus galapagoensis) were separated adequately into whey and casein fractions using bovine milk analysis methods. 2. In samples from days 5-30 of lactation 40% of the total proteins were whey and 60% caseins; in mid-lactation, day 150, 25% were whey and 75% casein proteins. 3. Electrophoretic and isoelectric focusing patterns of fur seal whey protein differed widely from bovine patterns, whereas those of caseins were similar. 4. Polymorphisms of fur seal whey and casein proteins were noted and did not seem related to different stages of lactation. 5. C-16 and C-18 fatty acids contributed about 70% of fatty acids; 63% of the total acids in milk fat were unsaturated.

Animals↗
PubMed1988

Purification and characterization of intestinal alkaline phosphatase from harp seal.

1. Alkaline phosphatase (EC 3.1.3.1.) from harp seal (Phagophilus groenlandicus) has been purified by concanavalin A-Sepharose chromatography to homogeneity with a specific activity of 1200-1500 units/mg of protein. 2. The mol. wt of the enzyme and its subunits were estimated as 260,000 and 70,000, respectively. By chromatofocusing the isoelectric point of this enzyme is 5.5. 3. With p-nitrophenylphosphate, pH-optimum and KM for the enzyme are 9.8 and 0.9 mM, respectively. 4. The enzyme was strongly inhibited by Sn4+, Fe3+ and Zn2+, whereas Mg2+ and Mn2+ were effective activators of the enzyme. Seal alkaline phosphatase was slightly inhibited by high concentrations of Ca2+ and Cr3+. 5. The enzyme activity reached a maximum at 55-60 degrees C. It was shown that the heat stability of seal and calf intestinal alkaline phosphatases were equal at 37 and 56 degrees C.

Alkaline Phosphatase↗
PubMed1995

Immunoglobulin A levels in southern elephant seal (Mirounga leonina) milk during the suckling period.

Immunoglobulin A (IgA) levels in milk samples from southern elephant seals at King George Island, Antarctica are reported. IgA levels were determined throughout the suckling period (approximately 23 days). The IgA concentration in southern elephant seal milk was lower than in other mammals and, unlike most mammalian milk, was not high during early lactation. There was not a definite pattern in IgA levels, which fluctuated within narrow limits throughout the suckling period (mean +/- SD, 30.81 +/- 6.38 mg IgA/100 g milk). If IgG was present, its level was too low to be detected by the method used. This is the first evidence in Southern elephant seal of the possibility of transmission of passive immunity after birth involving secretion of IgA in the milk.

Animals↗
PubMed1995

Characterisation of morbilliviruses isolated from Lake Baikal seals (Phoca sibirica).

Sequence analysis of the haemagglutinin protein (H) gene of the morbillivirus (PDV-2) isolated from a Siberian seal (Phoca sibirica) during the 1987/1988 epizootic in Lake Baikal revealed that it was most closely related to two recent isolates of canine distemper virus (CDV) from Germany and different from CDV vaccines currently in use in that region. The virus continued to circulate in seals in Lake Baikal after the 1987/1988 epizootic since sera collected from culled seals in the spring of 1992 were positive in morbillivirus ELISA tests, reacting most strongly with the CDV antigen.

Amino Acid Sequence↗
PubMed2026

Transcriptomic changes in the gut mucosa of fasting northern elephant seal pups reveal immune modulation during early microbiome establishment.

Fasting is an integral component of the life-history of many species. Following abrupt weaning, northern elephant seal pups (Mirounga angustirostris) undergo an extended post-weaning fast of approximately 60 days. During this period, enteric bacterial diversity increases, suggesting that host immune regulation may facilitate the establishment of microbial communities. However, the molecular processes occurring within the intestinal mucosa during this transition remain poorly understood. To investigate these mechanisms, we characterized transcriptional changes in the enteric mucosa of male and female northern elephant seal pups sampled at weaning and after one month of fasting. Total RNA isolated from rectal swabs was sequenced and aligned to the Mirounga angustirostris reference genome. Differential gene expression and gene set enrichment analyses were used to identify genes and pathways associated with fasting and sex-specific responses. Fasting was accompanied primarily by transcriptional downregulation, including genes involved in antimicrobial defense, inflammation, protein turnover, and epithelial remodeling. In contrast, several genes associated with B-cell activity and immune recognition were upregulated. Gene Set Enrichment Analysis revealed coordinated activation of immune-regulatory pathways indicating dynamic modulation of intestinal immunity rather than generalized immune suppression. Pronounced sex-specific differences were also observed. Male pups exhibited transcriptional patterns consistent with enhanced immune tolerance, whereas females showed broader immune-pathway activation, including enrichment of pro-inflammatory and stress-response pathways. Several non-coding RNAs also displayed sex-specific changes in expression. Together, these findings suggest that fasting induces transcriptional remodeling of the gut and may contribute to immune regulation during a critical period of microbiome establishment in northern elephant seal pups.

Animals↗
PubMed2006

Intravascular pressure profiles in elephant seals: hypotheses on the caval sphincter, extradural vein and venous return to the heart.

In order to evaluate hemodynamics in the complex vascular system of phocid seals, intravascular pressure profiles were measured during periods of rest-associated apnea in young elephant seals (Mirounga angustirostris). There were no significant differences between apneic and eupneic mean arterial pressures. During apnea, venous pressure profiles (pulmonary artery, thoracic portion of the vena cava (thoracic vena cava), extradural vein, and hepatic sinus) demonstrated only minor, transient fluctuations. During eupnea, all venous pressure profiles were dominated by respiratory fluctuations. During inspiration, pressures in the thoracic vena cava and extradural vein decreased -9 to -21 mm Hg, and -9 to -17 mm Hg, respectively. In contrast, hepatic sinus pressure increased 2-6 mm Hg during inspiration. Nearly constant hepatic sinus and intrathoracic vascular pressure profiles during the breath-hold period are consistent with incomplete constriction of the caval sphincter during these rest-associated apneas. During eupnea, negative inspiratory intravascular pressures in the chest ("the respiratory pump") should augment venous return via both the venae cavae and the extradural vein. It is hypothesized that, in addition to the venae cavae, the prominent para-caval venous system of phocid seals (i.e., the extradural vein) is necessary to allow adequate venous return for maintenance of high cardiac outputs and blood pressure during eupnea.

Animals↗