Seven species of fresh water fishes belonging to three different
families and two species of snails from Ritner Creek, Polk County,
Oregon were surveyed for adult and larval trematodes. A total of
seven species of trematodes representing four families was recovered
from the intestine of the fishes. Of these, at...
The presence of the etiologic agent of "salmon poisoning"
disease, Neorickettsia helminthoeca, was demonstrated in eggs of
the trematode vector, Nanophyetus salmincola. Three dogs were
given 100,000 and one dog 82,000 ground fluke eggs by intraperitoneal
injection. The four animals developed "salmon poisoning"
disease and died. One of these dogs...
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,...
Twenty yearling sheep were allotted to four groups, each containing
five sheep of approximately equal weight. On experimental
days 0, 1, 2, 3, and 4, each sheep in each group was given the following
inoculations by stomach tube: five sheep in group I (Fasciola
hepatica-exposed controls) were given approximately 120...
Sphaeromyxa maiyai sp. n. (Myxosporidea:Myxiidae) is described
from the gall bladder of the Pacific tomcod, Microgadus proximus
Girard, from Newport, Oregon. The plasmodial (=trophic, trophozoite)
stage is discoid averaging between 1 and 2 cm. The spore averages
27.6 x 5. 6μm with pyriform polar capsules averaging 9. 3 x 3....
During karyokinesis in the ciliate, Tetrahymena pyriformis, strain GL-I, an extranuclear chromatin body (ECB) is frequently formed as an excluded mass between the two dividing daughter macronuclei. The formation and fate of ECB's were followed by means of Feu lgen, toluidine blue 0, and euchrysine staining and autoradiography (³H-thymidine). The...
The causes of the global biodiversity crisis are varied and complex. Anthropogenic threats may act in isolation, or interact additively or synergistically with each other or with natural stressors to affect sensitive taxa. The recent emergence of many infectious diseases in wildlife has brought attention to the role of disease...
This dissertation focuses on the evolutionary forces of genetic drift and gene flow in frog populations. The balance of these two forces and the force of mutation largely determine the amount of neutral genetic variation within populations as well as the degree of genetic similarity among populations. The stochastic evolutionary...
In the past decade, declines in amphibian populations have captured scientific and popular interest. The causes of the declines are likely to be complex and involve interactions between several environmental stressors. Using multifactorial experiments, I investigated the combined effects of several anthropogenic stressors on developing amphibians in Oregon, USA. In...