Preliminary plots are required when beginning a cruise for a timber sale in order to get an idea of how much variation in volume exists within the sale area. This variation is known as the coefficient of variation (CV) and is subsequently used to estimate the number of plots needed to implement the cruise to a desired level of accuracy (allowable error). By looking at a large number of sale inventories and finding similarities among key attributes (trees per acre, diameter at breast height and an estimate of variance), two models were derived based on simple stand observations to aid field personnel in determining a more accurate estimate of the CV. Furthermore, the models estimate the number of 1/10 acre plots needed to sample a stand to within a ± 10% allowable error at the 90% confidence level for total tonnage.

Previous research documented that white-tailed deer body mass and antler size varied across physiographic regions of Mississippi. Deer from regions with greater soil fertility had greater body mass and antler size; however, this information is known only for individuals 6 months of age and older. I monitored birth mass and skeletal size of fawns produced by bred, adult, female white-tailed deer transplanted from the Delta, Thin Loess (Loess), and Lower Coastal Plain (LCP) soil regions to fawn in the Mississippi State University Rusty Dawkins Memorial Deer Unit. I evaluated the effect of soil region of origin, litter size, and fawn gender on mass and size of fawns at birth. Birth mass was not as variable as mass of older animals, but LCP fawns were lighter and shorter than loess and/or delta fawns. Twins were lighter and shorter than singletons. Males were heavier than females. Differences between regional birth dates within the pens and estimated regional birth dates based on a fetal growth curve raises questions about the wide-spread application of this method of estimating deer breeding and fawning dates.

Most cellular proteins retain a stable concentration as cells grow and divide, but there are exceptions. Some cell cycle regulators change in concentration with cell size. In fission yeast, Cdc13 (cyclin B), an important activator of the core cell cycle kinase Cdc2 (CDK1), increases in concentration as cells grow. It has been proposed that the concentration of such cell cycle regulators serves as a proxy for cell size and makes cell cycle progression dependent on cell size, thereby contributing to cell size homeostasis. The underlying mechanisms for the size-dependent scaling of these cell cycle regulators are poorly understood. Here, I show that Cdc13 protein concentration, but not mRNA concentration, increases with cell size. Furthermore, only the nuclear, but not the cytoplasmic, fraction of Cdc13 increases in concentration as cell size increases. Computational modeling along with half-life measurements suggests that stabilization of Cdc13 in the nucleus plays an important role in establishing this pattern. Taken together, my results suggest that Cdc13 scales with time, and therefore only indirectly—not directly—with cell size. This leaves open the possibility that Cdc13 contributes to cell size homeostasis, but in a different way than originally proposed. / Master of Science / Cells maintain their size very efficiently, but how they manage to do so is not well characterized. It has been suggested that cells sense their size by the size-dependent concentration changes of cell cycle proteins. I have investigated how cyclin B may serve as such a proxy for cell size in fission yeast. My data suggest that fission yeast cyclin B indirectly scales with cell size through an unknown time-based mechanism.

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