Biology Speaker

Robert Shields, PhD
Assistant Professor of Microbiology, Arkansas State University

A Functional Genomics Strategy to Unravel the Functions of Essential and Poorly Characterized Bacterial Genes

1:30 PM Friday – Graduate Hotel

In recent years, several microbial genomics techniques have been developed that have accelerated gene function discovery in bacteria. Our own research focuses on the study of critical but poorly characterized genes in Streptococcus mutans, a Gram-positive bacterium that colonizes the human oral cavity. Initially, by applying transposon sequencing (Tn-seq) and CRISPR interference (CRISPRi) we identified >200 essential genes that are required for the viability of the organism. With careful data inspection we determined that contained within the essential genome are eleven genes with unknown functions. Resolving the function of these genes is critical to understanding basic biology and molecular pathogenesis, and to developing more effective therapies against the pathogen. To begin to determine these functions, we have developed a strategy that allows us to characterize the phenotypic impact of loss of these genes on S. mutans. We begin by perturbing the amount of essential gene product using CRISPRi, and then we measure the phenotypic impact on cells with growth assays, ultrastructural microscopy, transcriptomics, and proteomics. We pair outcomes from these experiments with genetic suppressor screens. We attempt to mutate the essential genes and use genome sequencing to identify suppressor mutations which might highlight pathways/genes that interact with the hypothetical essential genes. Together, and with the inclusion of bioinformatic approaches, we have begun to understand the functions of some of the identified genes. For example, we have discovered a putative DNA-binding gene that may regulate aspects of the citric acid cycle. This gene is well conserved among Bacillota (formerly Firmicutes) bacteria. Our experimental strategy, and our findings, should identify critical essential functions in S. mutans and related Gram-positive microorganisms.

Chemistry Speaker

Tori Dunlap, PhD
Associate Professor of Chemistry and Biochemistry, University of Central Arkansas

Protein Disorder, Calcium Ion Signaling, and Neurodegenerative Diseases

2:00 PM Friday – Graduate Hotel

Structure leads to function, but sometimes lack of structure leads to function. In recent years a class of proteins known as intrinsically disordered proteins (IDPs) has been characterized. These proteins have no persistent secondary structure, and their 3D shapes exist on a continuum from expanded to compact. We now know that the lack of structure in these proteins is crucial for their function, and that IDPs are necessary for numerous cellular events. Also necessary for cellular function is calcium ion signaling. The main translator of the calcium signal is the protein calmodulin which, when bound to calcium ions, can then bind to and regulate an estimated 300 different proteins. Both disorder in proteins and calcium signaling are intertwined in neurodegenerative diseases. For many neurodegenerative diseases, the aggregation of an IDP has been implicated in the pathology, and calcium signal dysregulation also leads to neuronal cell disfunction or death. PEP19 is an IDP that is responsible for binding to calmodulin and regulating its ability to perpetuate the calcium signal. PEP19 concentrations are elevated in brain regions spared by Alzheimer’s Disease, and high levels of PEP19 protect against cell death caused by calcium ion overload. We utilized fluorescence and circular dichroism techniques to determine how the crowded conditions of a cell might influence PEP19’s 3D shape and how that would affect its ability to regulate calmodulin. We then investigated how the presence of neurodegenerative proteins involved in Alzheimer’s Disease and Parkinson’s Disease impacted PEP19’s shape and ability to interact with calmodulin. We determined that PEP-19 is somewhat compact but is further compacted by the presence of neurodegenerative proteins, making it more difficult for PEP19 to bind to a regulate calmodulin, likely increasing calcium ion signaling in neurodegenerative cell states.

Physics Speaker

Puskar Chapagain, PhD
Associate Professor of Physics, Southern Arkansas University

Synthesis and Characterization of Carbon Nanotubes-Alumina Nanocomposites

2:30 PM Friday – Graduate Hotel

Developing advanced materials with enhanced properties is crucial for various technological applications. Among these materials, carbon nanotubes (CNTs) are particularly promising due to their unique mechanical, thermal, optical, and electronic properties, which can significantly improve the performance of composite materials. Incorporating CNTs into ceramic matrices, such as alumina (Al2O3), we can create nanocomposites with multifunctional characteristics. This could potentially revolutionize electronics, medical devices, and energy storage. However, a major challenge lies in achieving a uniform distribution of CNTs within the Al2O3 matrix and understanding the behavior of these composites. To address this, we synthesized CNTs-Al2O3 nanocomposites using a chemical vapor deposition (CVD) process with nickel (Ni) catalysts to ensure proper bonding. We then analyzed the samples using various advanced techniques to study their structures and properties. Our findings show that the CNTs are evenly dispersed in the alumina matrix. Additionally, magnetic testing revealed that the composites with embedded Ni exhibit strong magnetic properties. This suggests that integrating CNTs with the alumina matrix in the presence of Ni could lead to innovative applications in magnetic sensors, data storage devices, and electromagnetic interference (EMI) shielding.