Purinergic modulation of neuronal gap junction circuits in the CNS of the leech.

Gap junctions (GJs) are widely distributed in brains across the animal kingdom. To visualize the GJ- coupled networks of two major mechanosensory neurons in the ganglia of medicinal leeches, we injected these cells with the GJ-permeable tracer Neurobiotin. When diffusion time was limited to only 30 min, tracer coupling was highly variable for both cells, suggesting a possible modulation of GJ permeability. In invertebrates the innexins (homologs of vertebrate pannexins) form the GJs. Because extracellular adenosine triphosphate (ATP) modulates pannexin and leech innexin hemichannel permeability and is released by leech glial cells following injury, we tested the effects of bath application of ATP after the injection of Neurobiotin and observed a significant increase in the number of neurons tracer coupled to the sensory neurons. This effect required the elevation of intracellular Ca2+ and could be produced by bath application of caffeine. Conversely, scavenging endogenous extracellular ATP with the ATPase apyrase decreased the number of coupled cells. ATP also increased electrical conductance and tracer permeability between the bilateral Retzius neurons. This modulatory effect of ATP on GJ coupling was blocked by siRNA knockdown of a P1-like adenosine receptor. Finally, exposure of leech ganglia to extracellular ATP induced a characteristic low frequency (<0.3 Hz) rhythmic bursting activity that was roughly synchronous among multiple neurons, a behavior that was significantly attenuated by the GJ blocker octanol. These findings highlight the mediation by ATP of a robust physiological mechanism for modifying neuronal circuits by rapidly recruiting neurons into active networks and entraining synchronized bursting activity.

The Making of Future Scientists: Faculty Mentor Cultural Awareness and Inclusive Science Labs.

A compelling body of research suggests that students from racially marginalized and minoritized (RMM) backgrounds are systematically deterred from Science, Technology, Engineering, and Math (STEM) fields when teachers and scientists create ideologically colorblind STEM learning environments where cultural differences are deemed irrelevant and disregard how race/ethnicity shapes students' experiences. We examine whether and how STEM faculty can serve as important sources of information that signal racial/ethnic diversity inclusion (or exclusion) that influence RMM students' motivation to persist in STEM. Specifically, we focus on RMM students' perceptions of their faculty research mentors' cultural awareness-the extent to which students believe that their faculty research mentor acknowledges and appreciates racial/ethnic differences in STEM research. Results from a longitudinal survey of RMM students (N = 150) participating in 74 faculty-led STEM research labs demonstrated that RMM students who perceived their faculty research mentor to be more culturally aware experienced more positive social climates in the lab and were more identified as scientists. Increased science identity, in turn, predicted their motivation to pursue STEM careers 3 months later. These findings demonstrate the importance of acknowledging, welcoming, and celebrating racial/ethnic diversity within STEM learning environments to broaden inclusive and equitable participation in STEM.