P33. Design and evaluation of an Escherichia coli biomarker for indication of pH

Measuring pH is one of the most commonly used techniques in both the laboratory as well as the field due to its importance in a multitude of biochemical processes. Traditional methods of measuring pH may be highly developed in accuracy and precision but often involve disruption of the environment. Biological markers offer an alternative that allows for long-term pH monitoring. This innovative approach allows for vast applications such as in the manufacturing, food processing and research industries. Under moderate acidic conditions, the asr (acid shock RNA) gene is highly inducible and has been demonstrated to be crucial for growth at high acidities. The alx locus in E. coli contains a putative transporter preceded by a pH-induced riboregulator that operates under moderately alkaline conditions. In this study, vivid blue/purple and green/blue chromoproteins, cJBlue and amilCP respectively, were used as visual indicators. DH5α competent E. coli cells were transformed with recombinant plasmids containing either amilCP downstream the asr promoter or cjBlue downstream the alx promoter and 5’UTR, giving rise to the alx-cjBlue and asr-amilCP cell lines. Through this methodology, we were able to create strains of E. coli that expressed either a blue or blue-green chromoprotein under low or high pHs respectively

Atrx Deletion in Neurons Leads to Sexually Dimorphic Dysregulation of miR-137 and Spatial Learning and Memory Deficits.

ATRX gene mutations have been identified in syndromic and non-syndromic intellectual disabilities in humans. ATRX is known to maintain genomic stability in neuroprogenitor cells, but its function in differentiated neurons and memory processes remains largely unresolved. Here, we show that the deletion of neuronal Atrx in mice leads to distinct hippocampal structural defects, fewer presynaptic vesicles, and an enlarged postsynaptic area at CA1 apical dendrite-axon junctions. We identify male-specific impairments in long-term contextual memory and in synaptic gene expression, linked to altered miR-137 levels. We show that ATRX directly binds to the miR-137 locus and that the enrichment of the suppressive histone mark H3K27me3 is significantly reduced upon the loss of ATRX. We conclude that the ablation of ATRX in excitatory forebrain neurons leads to sexually dimorphic effects on miR-137 expression and on spatial memory, identifying a potential therapeutic target for neurological defects caused by ATRX dysfunction

Fishing for the right probiotic: Investigating the mechanism of mucosal-bacterial interactions at the interface of health and productivity in salmonid aquaculture

Aquaculture is vital for the global food supply, but the high incidence of infectious diseases threatens the industry’s productivity. The intestinal mucosa is a key port of entry for pathogens and provides an extensive interface for host-microbe interactions. Tight junctions are at the core of gut barrier function and the mucosal health of finfish. Disruption of these complexes gives rise to sepsis, which leads to systemic inflammation and death. The present study employs a combinatorial approach that integrates in vitro and in vivo analyses to gain actionable insights into the mechanism of microbial-mediated modulation of host health. The experiments outlined in chapters 2 and 3 examine the suitability of several candidate probiotics for promoting gut barrier function, immunity, and mitigating the deleterious effects of the highly virulent aquatic pathogen Vibrio anguillarum. These studies demonstrate the importance of investigating the mechanism underlying host-microbe and microbe-microbe interactions for maximizing salmonid health