The nervous system grants animals the ability to react to the complex and ever-changing environment. The ability of the nervous system to control behavior relies not only on the functional properties of individual neurons, but also on the specific pattern of connections in the neural circuits that make up the brain. This dissertation presents the functional study of a simple circuit, specifically the egg-laying circuit in the nematode Caenorhabditis elegan, as a model to understand the principles by which networks of neurons generate behavioral patterns. We first studied the circuit mechanism for individual egg-laying events using neural imaging and laser microsurgery. Our results indicated that the HSN and VC motorneurons together with vulval muscles (vm1 and vm2) comprise a core circuit that produces egg- laying events upon activation in the absence of sensory inputs. HSN serves as the command neuron of this core circuit, while the VCs, which are reciprocally connected to HSNs, provide a negative feedback loop as well as redundantly exciting the vulval muscles. The roles of two neurotransmitters expressed in these motorneurons, acetycholine and serotonin, have been investigated by directly monitoring both the activities of neurons in the egg-laying circuit in biosynthetic mutants. With this information about the functional roles of the egg-laying neurons, the egg-laying circuit provides a nice system for studying the effects of specific receptors and channels on neuronal function. As an example, we characterized a newly cloned novel voltage gated cation channel, NCA-1, and demonstrated its function in cellbody-to-synapse excitation in the HSNs. Based on our results, we have proposed a theoretical model for how the clustered temporal pattern in the egg-laying behavior is generated in wild type animals. The VCs are suggested to work as "the single egg counter" that is activated by individual egg-laying events and inhibits the command neuron HSN for a short period of about 20 seconds. The uv1 cell may serve as "the cluster egg counter", activated by a cluster of closely spaced egg-laying events and inhibiting HSN activity for a longer time of about 20 minutes. Together, these two pathways could produce the observed clustered temporal pattern by acting as negative regulators acting on different time scales

Sensors in everyday devices, such as our phones, wearables, and computers, leave a stream of digital traces. Personal sensing refers to collecting and analyzing data from sensors embedded in the context of daily life with the aim of identifying human behaviors, thoughts, feelings, and traits. This article provides a critical review of personal sensing research related to mental health, focused principally on smartphones, but also including studies of wearables, social media, and computers. We provide a layered, hierarchical model for translating raw sensor data into markers of behaviors and states related to mental health. Also discussed are research methods as well as challenges, including privacy and problems of dimensionality. Although personal sensing is still in its infancy, it holds great promise as a method for conducting mental health research and as a clinical tool for monitoring at-risk populations and providing the foundation for the next generation of mobile health (or mHealth) interventions.

Symmetrical protein complexes are ubiquitous in biology. Many have been re-engineered for chemical and medical applications. Viral capsids and their assembly are frequent platforms for these investigations. A means to create asymmetric capsids may expand applications. Here, starting with homodimeric Hepatitis B Virus capsid protein, we develop a heterodimer, design a hierarchical assembly pathway, and produce asymmetric capsids. In the heterodimer, the two halves have different growth potentials and assemble into hexamers. These preformed hexamers can nucleate co-assembly with other dimers, leading to Janus-like capsids with a small discrete hexamer patch. We can remove the patch specifically and observe asymmetric holey capsids by cryo-EM reconstruction. The resulting hole in the surface can be refilled with fluorescently labeled dimers to regenerate an intact capsid. In this study, we show how an asymmetric subunit can be used to generate an asymmetric particle, creating the potential for a capsid with different surface chemistries.

Three undescribed 8,3'-neolignans, corynol (1), 3-methoxy-corynol (2) and 3'-deoxy-corynol (3), together with two bergenin derivatives, three flavonoids, two hydrolysable tannins and six simple phenolic compounds, were isolated from the twigs of Corylopsis coreana Uyeki. The structures of the 8,3'-neolignans were elucidated by analyzing their NMR, HRESIMS and ECD spectra. All the isolated compounds were evaluated for their SIRT1 stimulatory activity, and 3'-deoxy-corynol (3) showed SIRT1 stimulation activity. Furthermore, a docking study of 3 was performed with three representative binding pockets of SIRT1.