Publications

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streptococcus phocae infections associated with starvation in cape fur seals.mortalities and abortions associated with starvation occurred at cape cross, namibia, in cape fur seals (arctocephalus pusillus pusillus). affected seals showed lethargy and emaciation, and the most common pathological signs were those of a respiratory infection, both in adults and offspring. streptococcus phocae was isolated from adult seals, a cub and aborted foetuses.199910855831
dirofilaria immitis in pinnipeds and a new host record.dirofilaria immitis is a mosquito-borne pathogen that is spreading worldwide, and the associated infection (i.e. dirofilariosis) is becoming a threat to animals and humans living in endemic areas. little is known about the occurrence and risk of infection of d. immitis in pinnipeds. here we report dirofilariosis by d. immitis in several pinniped species kept in captivity in portugal.201728288690
metastatic liposarcoma in a south african fur seal (arctocephalus pusillus).a 14-year-old female south african fur seal (arctocephalus pusillus) was presented with a large skin mass on the right shoulder. at necropsy examination, multiple white nodules were found in the lungs, liver, spleen and right axillary lymph nodes. histologically, the skin mass was composed of round to polygonal neoplastic cells with round to oval nuclei and variably sized cytoplasmic vacuoles. cellular and nuclear atypia were prominent. immunohistochemically, the neoplastic cells expressed vimen ...201627290645
rod-cone based color vision in seals under photopic conditions.marine mammals have lost the ability to express s-cone opsin, and possess only one type of m/l-cone in addition to numerous rods. as they are cone monochromats they should be color blind. however, early behavioral experiments with fur seals and sea lions indicated discrimination ability between many shades of grey and blue or green. on the other hand, most recent training experiments with harbor seals under "mesopic" conditions demonstrated rod based color blindness (scholtyssek et al., 2015). i ...201627245870
brightness discrimination in the south african fur seal (arctocephalus pusillus).underwater, the contrast between object and background is much larger reduced with increasing distance between object and observer than in air. for marine predators, such as pinnipeds, it would therefore be advantageous to possess a high sensitivity for brightness differences, since this would increase the distance at which prey can be detected visually. few studies have examined the brightness discrimination thresholds of pinnipeds. two studies with phocid seals have confirmed low brightness di ...201323506966
olfactory discrimination ability of south african fur seals (arctocephalus pusillus) for enantiomers.using a food-rewarded two-choice instrumental conditioning paradigm we assessed the ability of south african fur seals, arctocephalus pusillus, to discriminate between 12 enantiomeric odor pairs. the results demonstrate that the fur seals as a group were able to discriminate between the optical isomers of carvone, dihydrocarvone, dihydrocarveol, menthol, limonene oxide, α-pinene, fenchone (all p < 0.01), and β-citronellol (p < 0.05), whereas they failed to distinguish between the (+)- and (-)-fo ...201323011284
accuracy of argos locations of pinnipeds at-sea estimated using fastloc gps.argos satellite telemetry is one of the most widely used methods to track the movements of free-ranging marine and terrestrial animals and is fundamental to studies of foraging ecology, migratory behavior and habitat-use. argos location estimates do not include complete error estimations, and for many marine organisms, the most commonly acquired locations (location class 0, a, b, or z) are provided with no declared error estimate.201020090942
an outbreak of lethal adenovirus infection among different otariid species.an outbreak of fatal fulminant hepatitis at a japanese aquarium involved 3 otariids: a california sea lion (zalophus californianus), a south african fur seal (arctocephalus pusillus) and a south american sea lion (otaria flavescens). in a span of about a week in february 2012, 3 otariids showed diarrhea and were acutely low-spirited; subsequently, all three animals died within a period of 3 days. markedly increased aspartate amino transferase and alanine amino transferase activities were observe ...201323643878
bilateral ocular anomalies in a south african fur seal (arctocephalus pusillus pusillus).a female south african fur seal (arctocephalus pusillus pusillus) began having obvious clinical ophthalmologic problems by 8 weeks of age. the initial clinical sign was diffuse corneal edema, which progressed to bullae formation and ulcers; the underlying cause of corneal edema and bullous keratopathy was not identified antemortem.an ophthalmological evaluation was performed when the fur seal was approximately 6 months of age, but due to the diffuse corneal edema, intraocular structures could no ...201424283987
activity budgets of captive cape fur seals (arctocephalus pusillus) under a training regime.ethograms and time budgets are crucial for the behavioral assessment of nonhuman animals in zoos, and they serve as references for welfare research. this study was conducted to obtain detailed time budgets of trained cape fur seals (arctocephalus pusillus) in captivity, to evaluate variations of these patterns, and to determine whether abnormal behaviors had been displayed. behavioral data for 3 cape fur seals in the wroclaw zoo were collected, and more than 300 observation hours (during a 12-mo ...201626709628
lack of functional alpha-lactalbumin prevents involution in cape fur seals and identifies the protein as an apoptotic milk factor in mammary gland involution.the mammary gland undergoes a sophisticated programme of developmental changes during pregnancy/lactation. however, little is known about processes involving initiation of apoptosis at involution following weaning. we used fur seals as models to study the molecular process of involution as these animals display a unique mammary gland phenotype. fur seals have long lactation periods whereby mothers cycle between secreting copious quantities of milk for 2 to 3 days suckling pups on land, with trip ...200818986549
sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys.many animals respond to predation risk by forming groups. evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. however, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator-prey systems. to solve this, we manipulated the domains of danger of cape fur seal (arctoc ...201019793737
a novel approach identified the folr1 gene, a putative regulator of milk protein synthesis.this study has utilised comparative functional genomics to exploit animal models with extreme adaptation to lactation to identify candidate genes that specifically regulate protein synthesis in the cow mammary gland. increasing milk protein production is valuable to the dairy industry. the lactation strategies of both the cape fur seal (artocephalus pusillus pusillus) and the tammar wallaby (macropus eugenii) include periods of high rates of milk protein synthesis during an established lactation ...200919669235
successful acquisition of an olfactory discrimination paradigm by south african fur seals, arctocephalus pusillus.the present study demonstrates that south african fur seals, arctocephalus pusillus, can successfully be trained to discriminate between objects on the basis of odor cues. using a task based on a food-rewarded two-choice discrimination of simultaneously presented odor stimuli the animals acquired the basic operant conditioning paradigm within 480 to 880 stimulus contacts. moreover, the fur seals could readily transfer to new s+ and s- stimuli, were capable of distinguishing between fish- and non ...200818291428
the tammar wallaby and fur seal: models to examine local control of lactation.mammary development and function are regulated by systemic endocrine factors and by autocrine mechanisms intrinsic to the mammary gland, both of which act concurrently. the composition of milk includes nutritional and developmental factors that are crucial to the development of the suckled young, but it is becoming increasingly apparent that milk also has a role in regulating mammary function. this review examines the option of exploiting the comparative biology of species with extreme adaptatio ...200717517753
species-specific cell-matrix interactions are essential for differentiation of alveoli like structures and milk gene expression in primary mammary cells of the cape fur seal (arctocephalus pusillus pusillus).few models are in place for analysis of extreme lactation patterns such as that of the fur seals which are capable of extended down regulation of milk production in the absence of involution. during a 10-12 month lactation period, female fur seals suckle pups on shore for 2-3 days, and then undertake long foraging trips at sea for up to 28 days, resulting in the longest intersuckling bouts recorded. during this time the mammary gland down regulates milk production. we have induced cape fur seal ...200616844361
the use of experimenter-given cues by south african fur seals (arctocephalus pusillus).dogs can use a variety of experimenter-given cues such as pointing, head direction, and eye direction to locate food hidden under one of several containers. some authors have proposed that this is a result of the domestication process. in this study we tested four captive fur seals in a two alternative object choice task in which subjects had to use one of the following experimenter-given cues to locate the food: (1) the experimenter pointed and gazed at one of the objects, (2) the experimenter ...200415057598
genetic evidence for two sibling species within contracaecum ogmorhini johnston & mawson, 1941 (nematoda: anisakidae) from otariid seals of boreal and austral regions.genetic variation of contracaecum ogmorhini (sensu lato) populations from different otariid seals of the northern and southern hemisphere was studied on the basis of 18 enzyme loci as well as preliminary sequence analysis of the mitochondrial cyt b gene (260 bp). samples were collected from zalophus californianus in the boreal region and from arctocephalus pusillus pusillus, a. pusillus doriferus and a. australis from the austral region. marked genetic heterogeneity was found between c. ogmorhin ...200312567006
electrophoretic detection of population variation within contracaecum ogmorhini (nematoda: ascaridoidea: anisakidae).this study examined genetic variation among specimens of contracaecum ogmorhini from different otariid hosts and geographical origins using a polymerase chain reaction (pcr)-based mutation detection approach. the first (its-1) and second (its-2) internal transcribed spacers (its) of ribosomal dna (rdna) were amplified individually by pcr, scanned for sequence variation by single-strand conformation polymorphism (sscp), and samples displaying variable sscp profiles were subjected to cycle sequenc ...200111465491
light and electron microscopical observations on the terminal airways and alveoli of the lung of the sa (cape) fur seal arctocephalus pusillus.during activities of the sea fisheries research institute at kleinzee, lung samples from six south african fur seals were collected. the terminal airways showed pseudostratified ciliated columnar epithelium with numerous goblet cells and occasional brush cells. smooth muscle, cartilage and submucosal glands were also present. the epithelium changed over a short distance, in the smaller airways, through pseudostratified columnar non-ciliated to simple cuboidal epithelium with no goblet cells. the ...199810192837
estimation of age from stained sections of canine teeth in the cape fur seal (arctocephalus pusillus pusillus).methods of cutting and staining thin sections of cape fur seal canines are described. the accuracy of age determination from the histology of the prepared sections and the suitability of the sectioning method is assessed. known-age canines were used to validate age determination. longitudinal sections along the midline enable growth layer groups (glgs) in the dentine to be counted along the length of the canine root. glgs in the cementum were either absent, or returned estimates of age that were ...19989722409
the endocrine pancreas of the cape fur seal, arctocephalus pusillus (schreber, 1776): an immunocytochemical study.the indirect peroxidase method was employed to study the endocrine pancreas of the cape fur seal. immunoreactivity to insulin was confined to the cores of the islets and the insulin cells were more abundant than the other endocrine cell types, which occurred mainly in the mantles of the islets. of these, glucagon cells were the most numerous, followed by somatostatin and pancreatic polypeptide (pp) cells. the latter were observed in the mantles of the islets and scattered in the exocrine tissue ...19979467181
genetic variation of southern hemisphere fur seals (arctocephalus spp.): investigation of population structure and species identity.we have examined phylogenetic and geographic patterns of variation in the mitochondrial cytochrome b gene of southern hemisphere fur seals (arctocephalus spp.). our survey of 106 individuals from four putative species reveals three distinct patterns of variation reflecting ancient, recent historic, and contemporary gene flow. for the combined samples of subantarctic (arctocephalus tropicalis) and antarctic (arctocephalus gazella) fur seals, we find low levels of sequence diversity and reciprocal ...19979183848
production of chitinase and beta-n-acetylglucosaminidase by intestinal bacteria of pinnipedian animals.the chitinase- and beta-n-acetylglucosaminidase(glcnacase)-producing ability of intestinal bacteria from pinnipedian animals was determined using fluorogenic 4-methylumbelliferone glycosides of n-acetylglucosamine oligosaccharides. intestinal microflora of a single cape fur seal, three california sea lions and three south american sea lions were characterized by a predominance of isolates of the bacteroidaceae and enterobacteriaceae families and the genus clostridium. of the 711 isolates tested ...19968987705
occurrence of taenia solium in a cape fur seal (arctocephalus pusillus).the larval stage of taenia solium was recovered from the brain, skeletal muscles, heart, lungs and liver of a cape fur seal collected near cape town. this is apparently the second record of the larval stage of this cestode in a marine mammal.19807413162
unilateral eeg activation during sleep in the cape fur seal, arctocephalus pusillus.sleep and wakefulness on the land were studied electrophysiologically in one adult female cape fur seal (arctocephalus pusillus). in two 24-h sessions, slow-wave sleep and paradoxical sleep averaged 27.4% and 4.6% of the total recording time. almost 40% of the total slow-wave sleep time was accounted for episodes with well-defined interhemispheric ecog asymmetry.19921436677
gross and microscopic visceral anatomy of the male cape fur seal, arctocephalus pusillus pusillus (pinnipedia: otariidae), with reference to organ size and growth.the gross and microscopic anatomy of the cape fur seal heart, lung, liver, spleen, stomach, intestine and kidneys (n = 31 seals) is described. absolute and relative size of organs from 30 male seals are presented, with histological examination conducted on 7 animals. the relationship between log body weight, log organ weight and age was investigated using linear regression. twenty five animals were of known age, while 6 were aged from counts of incremental lines observed in the dentine of tooth ...199910529060
variation in the fatty acid composition of blubber in cape fur seals (arctocephalus pusillus pusillus) and the implications for dietary interpretation.analysis of the fatty acid (fa) composition of blubber is a valuable tool in interpreting the diet of marine mammals. this technique is based on the principle that particular fa present in prey can be incorporated largely untransformed into predator adipose tissue stores, thereby providing biochemical signatures with which to identify prey species. several studies of phocid seals and cetaceans have documented vertical stratification in the fa composition of blubber such that inferences about die ...200515900509
olfactory discrimination of aliphatic odorants in south african fur seals (arctocephalus pusillus).using a food-rewarded, two-choice, instrumental conditioning paradigm we assessed the ability of south african fur seals, arctocephalus pusillus, to discriminate between members of five chemical classes of aliphatic odorants presumed to differ in their abundance in the marine chemical environment. we found that the fur seals were able to distinguish between 24 of the 25 odor pairs presented and thus have a well-developed ability to discriminate between structurally related odorants, that aliphat ...201020476818
thoracic auscultation in captive bottlenose dolphins (tursiops truncatus), california sea lions (zalophus californianus), and south african fur seals (arctocephalus pusillus) with an electronic stethoscope.thoracic auscultation is an important diagnostic method used in cases of suspected pulmonary disease in many species, as respiratory sounds contain significant information on the physiology and pathology of the lungs and upper airways. respiratory diseases are frequent in marine mammals and are often listed as one of their main causes of death. the aim of this study was to investigate and report baseline parameters for the electronic-mediated thoracic auscultation of one cetacean species and two ...201222779229
anesthetization of a cape fur seal (arctocephalus pusillus) for the treatment of a chronic eye infection and amputation of a metatarsal bone.tranquilization using 3 mg/kg of ketamine by intramuscular injection followed by inhalation anaesthesia using halothane was performed on an adult cape fur seal in order to perform a metatarsal amputation and ophthalmic examination. ketamine was found to have little effect at the dosage used while halothane proved to be a rapid induction agent providing a safe, continued level of surgical anaesthesia. variations in cardiac rate and body temperature were recorded during anesthasia and blood was sa ...19827182500
coping with heat: function of the natal coat of cape fur seal (arctocephalus pusillus pusillus) pups in maintaining core body temperature.cape fur seal (arctocephalus pusillus) pups spend the first weeks of life exclusively or mainly ashore. they are exposed to intense solar radiation and high temperatures for long time periods, which results in temperatures up to at least 80°c on their black natal coat. to test the hypothesis that the natal coat has a crucial function in coping with these extreme conditions, we investigated the insulating properties of the natal coat in six captive newborn cape fur seals during the first 50 days ...201323951287
a colostrum trypsin inhibitor gene expressed in the cape fur seal mammary gland during lactation.the colostrum trypsin inhibitor (cti) gene and transcript were cloned from the cape fur seal mammary gland and cti identified by in silico analysis of the pacific walrus and polar bear genomes (order carnivora), and in marine and terrestrial mammals of the orders cetartiodactyla (yak, whales, camel) and perissodactyla (white rhinoceros). unexpectedly, weddell seal cti was predicted to be a pseudogene. cape fur seal cti was expressed in the mammary gland of a pregnant multiparous seal, but not in ...201626639991
biannual otolith-zone formation of young shallow-water hake merluccius capensis in the northern benguela: age verification using otoliths sampled by a top predator.otoliths collected at least monthly from scat samples of cape fur seals arctocephalus pusillus are used to show that shallow-water hake merluccius capensis from the northern benguela develop three translucent zones in their first 1·5 years of life. the novel sampling approach provided otoliths that belonged to four m. capensis cohorts of approximate known age (hatched in 1996, 1998, 2002 and 2005), allowing age verification. following spawning in austral winter, translucent zones consistently fo ...201525990746
comparison of pinniped and cetacean prey tissue lipids with lipids of their elasmobranch predator.the great white shark is known to include pinnipeds and cetaceans in its diet. both groups of marine mammals deposit thick blubber layers around their bodies. elasmobranchs do not produce adipose tissue, but rather store lipid in their livers, thus a great white predating on a marine mammal will deposit the lipids in its liver until required.201424632977
residency, habitat use and sexual segregation of white sharks, carcharodon carcharias in false bay, south africa.white sharks (carcharodon carcharias) are threatened apex predators and identification of their critical habitats and how these are used are essential to ensuring improved local and ultimately global white shark protection. in this study we investigated habitat use by white sharks in false bay, south africa, using acoustic telemetry. 56 sharks (39 female, 17 male), ranging in size from 1.7-5 m tl, were tagged with acoustic transmitters and monitored on an array of 30 receivers for 975 days. to i ...201323383052
laminae in the teeth of the cape fur seal used for age determination. 1978634039
olfactory discrimination ability of asian elephants (elephas maximus) for structurally related odorants.using a food-rewarded two-choice instrumental conditioning paradigm, we assessed the ability of asian elephants, elephas maximus, to discriminate between 2 sets of structurally related odorants. we found that the animals successfully discriminated between all 12 odor pairs involving members of homologous series of aliphatic 1-alcohols, n-aldehydes, 2-ketones, and n-carboxylic acids even when the stimuli differed from each other by only 1 carbon. with all 4 chemical classes, the elephants display ...201323246848
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