LIFE CYCLE AND COMMUNITY STRUCTURE OF MAYFLIES (INSECTA: EPHEMEROPTERA) AND CHIRONOMIDS (INSECTA: CHIRONOMIDAE) IN THE NAVASOTA RIVER, TEXAS.

Research focused upon the structure and function of low elevation, turbid lotic ecosystems is lacking throughout much of the southeastern United States. This lack of basic ecological data severely hampers decision makers involving management of freshwater resources. The Navasota River, a low elevation, turbid lotic ecosystem, originates in southeast Hill County (in east Texas) and flows approximately 125 miles south to join the Brazos River. Only limited data is available concerning the invertebrate communities and ecological functions these communities contribute to the Navasota River. The purpose of this study was to gain a better understanding of the life cycle and community structure of mayflies (Insecta: Ephemeroptera) and chironomids (Insecta: Diptera) in the Navasota River, near where it joins the Brazos River. Quantitative samples were obtained approximately every four weeks from August 2014 through July 2015. The majority of chironomids were represented by the subfamily Tanypodinae. However, it was not possible to determine species for a variety of reasons. Chironomids were most common from January through July, with relatively small numbers of individuals from August through December. Mayflies were most common in September and October. Most of the mayflies were determined to be from the genus Beatis

Tunable Pentapeptide Self-Assembled β-Sheet Hydrogels.

Oligopeptide-based supramolecular hydrogels hold promise in a range of applications. The gelation of these systems is hard to control, with minor alterations in the peptide sequence significantly influencing the self-assembly process. We explored three pentapeptide sequences with different charge distributions and discovered that they formed robust, pH-responsive hydrogels. By altering the concentration and charge distribution of the peptide sequence, the stiffness of the hydrogels could be tuned across two orders of magnitude (2-200 kPa). Also, through reassembly of the β-sheet interactions the hydrogels could self-heal and they demonstrated shear-thin behavior. Using spectroscopic and cryo-imaging techniques, we investigated the relationship between peptide sequence and molecular structure, and how these influence the mechanical properties of the hydrogel. These pentapeptide hydrogels with tunable morphology and mechanical properties have promise in tissue engineering, injectable delivery vectors, and 3D printing applications