Bone histology, the study of bone tissue, has become a critical tool in the field of paleobiology as a proxy for life-history information, such as growth rates, that is otherwise inaccessible from fossils. However, the bulk of bone histological research has focused on birds, crocodilians, and large-bodied mammals, leaving the extent to which bone microstructure acts as an indicator of growth rates among small mammals largely unknown. Therefore, we generated thin sections from the limb bones (e.g., tibiae, humeri, and femora) of a taxonomically diverse sample of 12 extant, small-bodied (<1 kg) mammals in an attempt to build a framework upon which we may make inferences about the evolution of mammalian growth dynamics. In general, vascularity is low or absent in our samples, and the degree of vascularity appears to decrease with decreasing body mass. All specimens exhibit two types of bone matrix: well-organized parallel-fibered bone and disorganized woven bone. Often, this parallel-fibered tissue lines the interior and exterior of the bone cortex, bordering an intermediate band of woven tissue. This middle band likely represents a period of rapid bone deposition, possibly corresponding with rapid growth in early ontogeny, while the parallel-fibered bone represents deposition after growth had slowed. We hypothesize that the structurally competent parallel-fibered bone bordering the cortex may act to buffer the intermediate, structurally weak, woven bone against mechanical strain during locomotion. To test these hypotheses, we will compile existing life-history data and quantify the histological features of our sample using NIS Elements photo documentation software, and apply multiple linear regression models to test for relationships of significance. By investigating the impact of life-history characteristics upon small mammal bone microstructure, we hope to make important inferences about the lives of extinct small mammals, and thus create a more comprehensive understanding of mammalian growth dynamics. 

Probiotics are an area of significant clinical research, as they have been shown to aid digestion, fight infections, and even mitigate irritable bowel syndrome; however, probiotic colonies must grow and thrive in the extreme pH environment present in the human digestive tract. Previous experiments focused on the production of the surface protein Elongation Factor Thermally Unstable (EF-Tu), which attaches to glycoproteins lining the intestines and has been used as a biomarker for probiotic health. The growth of several strains of probiotics (Lactobacillus bulgaricus, Lactobacillus acidophilus, and Bifidobacterium longum) in both lysogeny broth (LB) and De Man, Rogosa, and Sharpe broth (MRS) was evaluated. The fractions of secreted, cytosolic, and membrane proteins were quantified using a Bradford assay. Finally, the relative amount of EF-Tu was determined by tryptic digestion and liquid chromatography-mass spectrometry (LC-MS). LB was found to be a more effective growth medium for the range of bacteria tested, with 24 hours at 37°C the ideal incubation period. To isolate the secreted proteins, the supernatant was drawn off the broth culture after centrifugation. Freeze-thaw lysis was used to extract cytosolic proteins, with three cycles determined as optimal for protein recover. Sodium deoxycholate was used to separate proteins from the membrane. All three protein samples were separated and run through a sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and the EF-Tu bands (roughly 43 kDa) were excised and sent for analysis by LC-MS. Using the information obtained from this research study, pharmaceutical companies can create more suitably tailored probiotic products, and make them more accessible and understandable to the general population. 

Imidacloprid is the most widely used agricultural pesticide in the world. As a neonicotinoid, it is highly potent against insects while having low toxicity to mammals. One area of concern is its effect on honeybees, possibly playing a role in colony collapse disorder (CCD), a sudden disappearance of worker bees from an otherwise healthy population. Bees are known to be sensitive to imidacloprid at high concentrations, but what is unclear is whether chronic exposure to the low doses used to protect crops can also be harmful. The E.U. and Canada have taken steps to ban the use of imidacloprid as a precaution, and the U.S. EPA has warned users of its potential for leaching into groundwater. It may also persist for years in soil, pollen, and nectar. Due to its low volatility, high boiling point, and high solubility in polar solvents, imidacloprid can be difficult to reliably detect in environmental samples using current gas chromatography (GC) methods. To address this, we evaluated GC-MS detection of imidacloprid in methanol standards, spiked water, and spiked honey. Samples were evaluated after clean-up with both C18 solid-phase extraction (SPE) and dispersive solid-phase extraction (DSPE) methods, using two different GC columns (Restek Rxi-5MS and Rtx-1701). Samples were also subjected to a range of pH conditions, and ionized by both electron ionization (EI) and chemical ionization (CI). As GC is typically faster, cheaper, and easier than liquid chromatography, currently the method of choice for detection of neonicotinoids, our research could benefit the study of imidacloprid toxicity by reducing the attendant time, cost, and training requirements. Preliminary results have shown reliable detection of imidacloprid-urea, the main hydrolysis compound of imidacloprid, at pH 5-7.