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Biology

Old Dominion University

Physiology

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Full-Text Articles in Life Sciences

Polar Bear Behavior: Morphologic And Physiologic Adaptations, John P. Whiteman Jan 2021

Polar Bear Behavior: Morphologic And Physiologic Adaptations, John P. Whiteman

Biological Sciences Faculty Publications

Polar bears possess morphologic and physiologic characteristics that reflect their terrestrial lineage as members of the bear family (Ursidae) as well as adaptations to the Arctic marine environment. Among marine mammals, they are the least adapted for aquatic life. They exhibit substantial seasonality in body mass, body condition, and many physiological functions, reflecting the annual cycle of both their Arctic sea ice habitat and the availability of their main prey, ringed seals. This hypercarnivorous diet has likely influenced the polar bear’s craniodental morphology and nutritional physiology. Similar to other marine mammal predators, polar bears exhibit a relatively high resting metabolic …


Vitellogenin Receptor As A Target For Tick Control: A Mini-Review, Robert D. Mitchell Iii, Daniel E. Sonenshine, Adalberto A. Pérez De León Jan 2019

Vitellogenin Receptor As A Target For Tick Control: A Mini-Review, Robert D. Mitchell Iii, Daniel E. Sonenshine, Adalberto A. Pérez De León

Biological Sciences Faculty Publications

While much effort has been put into understanding vitellogenesis in insects and other organisms, much less is known of this process in ticks. There are several steps that facilitate yolk formation in developing oocytes of which the vitellogenin receptor (VgR) is a key component. The tick VgR binds vitellogenin (Vg) circulating in the hemolymph to initiate receptor-mediated endocytosis and its transformation into vitellin (Vn). The conversion of Vg into Vn, the final form of the yolk protein, occurs inside oocytes of the female tick ovary. Vn is critical to tick embryos since it serves as the nutritional source for their …