Sex differentiation in fish is a labile process that allows sex inversion in several species. The inherent capacity of fish germ cells to differentiate into oocytes or spermatocytes constitutes a key factor allowing for functional sex inversion. This thesis set out to determine the mechanism involved in steroid-induced sex differentiation...
This study examined fish movements and assemblage dynamics in the Wenaha, Grande Ronde, Snake river system of northeast Oregon and southeast Washington. I investigated the role of fish movement in the dynamics of stream fish assemblages and evaluated relationships between species movement, assemblage structure, and the heterogeneity of habitat at...
In recent years considerable interest has been shown in the diversity of ammonia-oxidizing bacteria in soil communities. The majority of the research has been carried out in Northern Europe where soils have received high atmospheric inputs of nitrogen over the past two centuries. In contrast, although much work has been...
With respect to a multienzyme complex of deoxyribonucleoside triphosphate (dNTP) synthesis somehow juxtaposed with DNA replication sites, our laboratory has demonstrated the existence of a multienzyme complex in T4-infected E. coli, named the T4 dNTP synthetase complex, but the idea of direct linkage of dNTP synthesis to DNA replication and...
Previous attempts to understand the factors affecting the energetic cost of locomotion have found a direct link between the energetic cost and the mechanical work done during periods when the limb is in contact with the ground. However, when the limb is not in contact with the ground during the...
We evaluated the regeneration behavior and early growth rates of 10 non-pioneer canopy tree species in medium-height, semi-evergreen dry tropical forest in Quintana Roo, Mexico. These species provide timber and non-timber forest products for local communities and include evergreen and deciduous species with varied dispersal mechanisms. The species were Coccoloba...
Accurate chromosome segregation and cell cleavage are critical to maintaining genomic integrity. Both events involve the spindle apparatus, but the exact mechanics is as puzzling as the contradicting models proposed in the last two centuries. In this dissertation, current prevailing models of chromosome segregation and cell cleavage are tested using...
Understanding how N availability influences base cation stores is critical for long-term ecosystem sustainability. Indices of nitrogen (N) availability and the distribution of nutrients in plant biomass, soil, and soil water were examined across ten young, unpolluted Douglas-fir (Pseudotsuga menziesii) stands in the Oregon Coast Range spanning a three-fold soil...
Sustainable management of planted forests requires maintenance of soil function
to promote 1) root growth; 2) storage and cycling of water and nutrients; 3) optimal gas
exchange; and 4) biological activity. Soil quality measurements can be used to monitor
short- and long-term changes in these soil functions, allowing managers to...
The Pacific Northwest has a relatively low diversity of primary freshwater fishes with most of the endemism and diversity in the Columbia River and Klamath River. However, the Oregon Coastal Subprovince defined as the coastal rivers from Miami River in the north to Sixes River in the south, has a...