Rapid rates of biodiversity loss have supported the notion that Earth is experiencing a sixth major extinction event. The causes of worldwide biodiversity loss are multifaceted and context dependent. One of the most prominent groups experiencing population declines and extinctions are amphibians. Several pathogens and their associated diseases are especially...
Acid and alkaline phosphatase was localized histochemically in the intestinal epithelium and excretory duct respectively in fresh
frozen sections of Fasciola hepatica. Polyphenol oxidase was
localized in the vitellaria, vitelline ducts and egg-shells. The distribution
and nature of esterases was examined histochemically. Acetyl-cholinesterase
was observed in the tegument, neural ganglia,...
This thesis describes studies that investigated 1)
the effects of courtship on the neuroendocrine system of
female rough-skinned newts, Taricha granulosa, and 2)
whether the observed courtship-induced neuroendocrine
changes affected female sexual receptivity.
Sexual behaviors of female T. granulosa changed
dramatically during courtship. Initially, females
exhibited unreceptive behaviors to a...
One hypothesis proposed to explain how the endocrine
system controls reproductive cycles in seasonally breeding
animals is that the hypothalamus undergoes seasonal
changes in sensitivity to negative feedback by gonadal
steroids. The result is seasonal changes in the secretion
of luteinizing hormone-releasing hormone (LHRH) and
gonadotropin secretion. The present experiments...
From British Columbia to northern California, coastal giant salamanders (Dicamptodon tenebrosus) are a dominant vertebrate predator in headwater streams. Though widespread, salamander health and abundance levels differ greatly between locations, provoking the question as to what factors may influence this variation and whether habitat features or biotic variables play a...
Because arginine vasotocin (AVT) activates male sexual behaviors in the rough-skinned newt (Taricha granulosa), quantitative autoradiography with radiolabelled arginine vasopressin (³H-AVP) was used to localize and characterize putative AVT receptors in the brain of this amphibian. Binding of ³H-AVP to sites within the medial pallium was saturable, specific, reversible, of...
