<p> Echinoid larvae exhibit phenotypic plasticity, where development of long ciliary bands in low-food conditions is considered advantageous for improved algal particle capture. Conversely, larvae in concentrated algal conditions redirect growth to persisting structures (i.e. not lost during metamorphosis) and develop quickly. This study seeks to understand the organismal growth efficiency of sand dollar larvae (<i>Dendraster excentricus</i>) with different phenotypes by comparing larvae developing in low and high algal concentrations (1,000 and 10,000 algal cells ml^&ndash;1, respectively). I measured ingestion, metabolism, and biomass growth rates (protein and lipid) during larval development in three independent cultures. Resulting phenotypes demonstrated morphological divergence, where high-fed larvae grew smaller arms relative to stomach size (a remaining post-metamorphic feature) compared to low-fed larvae. Physiological data were converted to energetic units (mJ) to determine assimilation and growth efficiencies. Low-fed larvae proportionally allocated more energy to metabolism while the high-fed larvae allocated more toward growth. This resulted in different assimilation and growth efficiencies in low- and high-fed treatments. The energetic demands and organismal growth efficiencies of these contrasting phenotypes is important for understanding the constraints on population connectivity of adult populations in rapidly changing marine conditions.</p><p>

<p> Many neurological diseases associated with cortical and hippocampal dysfunctions are sexually dimorphic in incidence and have been linked to defects in mRNA splicing. My thesis investigated the sex- and age-related changes in gene expression of six RNA processing genes within the cortex/hippocampus of male and female mice during early development. Gene expression was measured using RT-qPCR with mouse cortex/hippocampus samples collected on the day of birth and one week after birth. Immunoblotting was also used to measure the protein levels of one RNA processing gene to determine whether the expression paralleled mRNA expression. <i>Dhx8 mRNA</i> and <i>Sf3a2 </i> protein expression was found to be sexually dimorphic, while <i> Thoc3, Tut1,</i> and <i>Sf3a2</i> showed mRNA expression changes with age. Sexually dimorphic and age-related expression of these genes suggests that RNA processing may play an important role in brain sexual differentiation and early neural development; however the underlying mechanisms remain to be elucidated.</p>