Scott C. Molitor

Tyramine receptor (SER-2) isoforms are involved in the regulation of pharyngeal pumping and foraging behavior in Caenorhabditis elegans

Octopamine regulates essential processes in nematodes; however, little is known about the physiological role of its precursor, tyramine. In the present study, we have characterized alternatively spliced Caenorhabditis elegans tyramine receptor isoforms (SER‐2 and SER‐2A) that differ by 23 amino acids within the mid‐region of the third intracellular loop. Membranes prepared from cells expressing either SER‐2 or SER‐2A bind [3H]lysergic acid diethylamide (LSD) in the low nanomolar range and exhibit highest affinity for tyramine. Similarly, both isoforms exhibit nearly identical Ki values for a number of antagonists. In contrast, SER‐2A exhibits a significantly lower affinity than SER‐2 for other physiologically relevant biogenic amines, including octopamine. Pertussis toxin treatment reduces affinity for both tyramine and octopamine, especially for octopamine in membranes from cells expressing SER‐2, suggesting that the conformation of the mid‐region of the third intracellular loop is dictated by G‐protein interactions and is responsible for the differential tyramine/octopamine affinities of the two isoforms. Tyramine reduces forskolin‐stimulated cAMP levels in HEK293 cells expressing either isoform with nearly identical IC50 values. Tyramine, but not octopamine, also elevates Ca2+ levels in cells expressing SER‐2 and to a lesser extent SER‐2A. Most importantly, ser‐2 null mutants (pk1357) fail to suppress head movements while reversing in response to nose‐touch, suggesting a role for SER‐2 in the regulation of foraging behavior, and fail to respond to tyramine in assays measuring serotonin‐dependent pharyngeal pumping. These are the first reported functions for SER‐2. These results suggest that C. elegans contains tyramine receptors, that individual SER‐2 isoforms may differ significantly in their sensitivity to other physiologically relevant biogenic amines, such as octopamine (OA), and that tyraminergic signaling may be important in the regulation of key processes in nematodes.

Effects of near-infrared laser exposure in a cellular model of wound healing.

Background: Clinical studies have demonstrated beneficial outcomes for low‐level laser therapy (LLLT) using near‐infrared (NIR) wavelengths. It has been hypothesized that the benefits of NIR LLLT are due in part to the thermal effects of NIR exposure. However, it is not clear whether photochemical interactions between NIR light and superficial tissues contribute to beneficial outcomes. To investigate the photochemical effects of NIR exposure, the efficacy of 980 nm NIR LLLT on human fibroblast growth rates is investigated using an in vitro model of wound healing.

Insulin and Leptin Signaling Interact in the Mouse Kiss1 Neuron during the Peripubertal Period

Reproduction requires adequate energy stores for parents and offspring to survive. Kiss1 neurons, which are essential for fertility, have the potential to serve as the central sensors of metabolic factors that signal to the reproductive axis the presence of stored calories. Paradoxically, obesity is often accompanied by infertility. Despite excess circulating levels of insulin and leptin, obese individuals exhibit resistance to both metabolic factors in many neuron types. Thus, resistance to insulin or leptin in Kiss1 neurons could lead to infertility. Single deletion of the receptors for either insulin or the adipokine leptin from Kiss1 neurons does not impair adult reproductive dysfunction. However, insulin and leptin signaling pathways may interact in such a way as to obscure their individual functions. We hypothesized that in the presence of genetic or obesity-induced concurrent insulin and leptin resistance, Kiss1 neurons would be unable to maintain reproductive function. We therefore induced a chronic hyperinsulinemic and hyperleptinemic state in mice lacking insulin receptors in Kiss1 neurons through high fat feeding and examined the impact on fertility. In an additional, genetic model, we ablated both leptin and insulin signaling in Kiss1 neurons (IR/LepRKiss mice). Counter to our hypothesis, we found that the addition of leptin insensitivity did not alter the reproductive phenotype of IRKiss mice. We also found that weight gain, body composition, glucose and insulin tolerance were normal in mice of both genders. Nonetheless, leptin and insulin receptor deletion altered pubertal timing as well as LH and FSH levels in mid-puberty in a reciprocal manner. Our results confirm that Kiss1 neurons do not directly mediate the critical role that insulin and leptin play in reproduction. However, during puberty kisspeptin neurons may experience a critical window of susceptibility to the influence of metabolic factors that can modify the onset of fertility.

Investigating the Impact of NGSS-Aligned Professional Development on PreK-3 Teachers’ Science Content Knowledge and Pedagogy

This pilot study investigates the impact of a 2-week professional development Summer Institute on PK-3 teachers’ knowledge and practices. This Summer Institute is a component of [program], a large-scale early-childhood science project that aims to transform PK-3 science teaching. The mixed-methods study examined concept maps, lesson plans, and classroom observations to measure possible changes in PK-3 teachers’ science content knowledge and classroom practice from 11 teachers who attended the 2014 Summer Institute. Analysis of the concept maps demonstrated statistically significant growth in teachers’ science content knowledge. Analysis of teachers’ lesson plans demonstrated that the teachers could design high quality science inquiry lessons aligned to the Next Generation Science Standards following the professional development. Finally, examination of teachers’ pre- and post-Summer Institute videotaped inquiry lessons showed evidence that teachers were incorporating new inquiry practices into their teaching, especially regarding classroom discourse. Our results suggest that an immersive inquiry experience is effective at beginning a shift towards reform-aligned science and engineering instruction but that early elementary educators require additional support for full mastery.