Dataset Information

Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal.

ABSTRACT: Whisker touch is an active sensory system. Previous studies in Pinnipeds have adopted relatively stationary tasks to judge tactile sensitivity, which may not accurately promote natural whisker movements and behaviours. This study developed a novel feeding task, termed fish sweeping to encourage whisker movements. Head and whisker movements were tracked from video footage in Harbor seal (Phoca vitulina), California sea lion (Zalophus californianus) and Pacific walrus (Odobenus rosmarus divergens). All species oriented their head towards the moving fish target and moved their whiskers during the task. Some species also engaged in whisker control behaviours, including head-turning asymmetry in the Pacific walrus, and contact-induced asymmetry in the Pacific walrus and California sea lion: behaviours that have only previously been observed in terrestrial mammals. This study confirms that Pinnipeds should be thought of as whisker specialists, and that whisker control (movement and positioning) is an important aspect of touch sensing in these animals, especially in sea lions and walruses. That the California sea lion controls whisker movement in relation to an object, and also had large values of whisker amplitude, spread and asymmetry, suggests that California sea lions are a promising model with which to further explore active touch sensing.

SUBMITTER: Milne AO

PROVIDER: S-EPMC7192888 | biostudies-literature | 2020 May

REPOSITORIES: biostudies-literature

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Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal.

Milne Alyxandra O AO Smith Catherine C Orton Llwyd D LD Sullivan Matthew S MS Grant Robyn A RA

Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology 20200220 3

Whisker touch is an active sensory system. Previous studies in Pinnipeds have adopted relatively stationary tasks to judge tactile sensitivity, which may not accurately promote natural whisker movements and behaviours. This study developed a novel feeding task, termed fish sweeping to encourage whisker movements. Head and whisker movements were tracked from video footage in Harbor seal (Phoca vitulina), California sea lion (Zalophus californianus) and Pacific walrus (Odobenus rosmarus divergens) ...[more]

PMID: 32077991

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Project description:Alzheimer's disease (AD) is characterized by the accumulation of amyloid-? (A?) as senile plaques and cerebral amyloid angiopathy, and hyperphosphorylated tau (hp-tau) as neurofibrillary tangles in the brain. The AD-related pathology has been reported in several non-human animals, and most animals develop only the A? or tau pathology. We herein describe the A? and hp-tau pathology in the brains of aged pinniped species (seal, sea lion, and walrus). Molecular analyses revealed that the sequence of pinniped A? was identical to that of human A?. Histopathological examinations detected argyrophilic plaques composed of A? associated with dystrophic neurites in the cerebral cortex of aged pinnipeds. Astrogliosis and microglial infiltration were identified around A? plaques. A? deposits were observed in the blood vessel walls of the meninges and cerebrum. Pinniped tau protein was physiologically subjected to alternative splicing at exons 2, 3, and 10, and presented as five isoforms: two 3-repeat tau isoforms (1N3R, 2N3R) and three 4-repeat tau isoforms (0N4R, 1N4R, 2N4R); 0N3R tau isoform was absent. Histopathological examinations revealed argyrophilic fibrillar aggregates composed of hp-tau in the neuronal somata and neurites of aged pinniped brains. Few hp-tau aggregates were found in oligodendrocytes and microglia. Biochemically, hp-tau of the 3-repeat and 4-repeat isoforms was detected in brain sarkosyl-insoluble fractions. A? and hp-tau both predominantly accumulated in the neocortex, particularly the frontal cortex. Furthermore, the activation of GSK-3? was detected within cells containing hp-tau aggregates, and activated GSK-3? was strongly expressed in cases with severe hp-tau pathologies. The present results suggest that, in association with A? deposition, the activation of GSK-3? contributes to hp-tau accumulation in pinniped brains. Here, we report that pinniped species naturally accumulate A? and tau with aging, similar to the human AD pathology.

Project description:Keratinized tissues, including whiskers, are ideal for acquiring a record of physiological parameters. Most tissues provide a snapshot of physiological status; however, whiskers may support longitudinal sampling for reproductive and stress-related hormones, if hormones are incorporated as whiskers grow and concentrations change with physiological state. Whiskers from female Steller sea lions (Eumetopias jubatus) and northern fur seals (Callorhinus ursinus) were serially sectioned and pulverized and steroid hormones were extracted. Standard methods were used to validate enzyme immunoassay kits for cortisol, progesterone, 17β-estradiol and testosterone. All hormones were measurable in whisker segments from both species with progesterone concentrations showing cyclical patterns, which appear to signify previous pregnancies or luteal phases. Yearly progesterone concentrations were greater in years a pup was produced compared with years when no pup was observed. Free-ranging female Steller sea lions had reproductive rates between 0 and 1.0 (0.53 ± 0.33, n = 12) using a yearly progesterone concentration of 30 pg/mg or greater to classify a reproductive year as producing a pup and below 30 pg/mg as non-reproductive. Cortisol concentrations were greater near the root and rapidly declined, lacking any obvious patterns, throughout the rest of the whisker. Progesterone and testosterone concentrations were able to help determine sex of unknown individuals. Immunohistochemistry revealed that steroid hormones most likely do not leach out of whiskers based on the deposition patterns of progesterone and cortisol being present throughout the whisker length. Overall, measuring steroid hormones in whiskers can reveal individual reproductive histories over multiple years in sea lions and fur seals. Cyclical patterns of δ15N were useful for identifying periods of up to ~10 years of growth within whiskers, and measuring both stable isotopes and hormones may be useful for differentiating periods of active gestation from diapause and potentially track multi-year reproductive histories of female otariids.

Dataset Information

Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal.

Publications

Pinnipeds orient and control their whiskers: a study on Pacific walrus, California sea lion and Harbor seal.

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