Functional Genomics and physiology of growth initiation in Salmonella

Abstract Lag phase is a period of bacterial adaptation that occurs prior to cell division. The aim of this project was to characterise the processes used by Salmonella enterica serovar Typhimurium to escape from lag phase, and determine whether these processes are dependent on the bacterial ‘physiological history’. The lag phase transcriptomic response at 25 °C of stationary phase cells that had been held for twelve days at 2 °C was compared with that of stationary phase cells not subjected to this cold storage treatment. Cold-stored cells showed significant changes in expression of 78 % genes during lag phase, with 875 genes altering their expression ≥2-fold within the first four minutes of inoculation into fresh medium. Functional categories of genes that were significantly up-regulated included those encoding systems involved with metal ion uptake, stress resistance, phosphate uptake, ribosome synthesis and cellular metabolism. Genes in the OxyR regulon were induced earlier in cold-stored cells, a response coupled with a delay in the expression of Fe2+ acquisition genes, and down-regulation of genes encoding central metabolic enzymes. Together, these findings with physiological tests demonstrated that Salmonella held in cold storage exhibited an increased sensitivity to oxidative stress in midlag phase, although the lag time was not increased. Despite an oxidative stress response at the transcriptomic level during lag phase under both experimental conditions, deletion of the OxyR and SoxRS systems did not lead to an increased lag time during aerobic growth at 25 °C. The intracellular concentration of metal ions was quantified using ICP-MS, and changes observed during lag phase confirmed the transcriptomic data. Metal ions specifically accumulated during lag phase included Mn2+, Fe2+, Cu2+ and Ca2+, with the latter being the most abundant metal ion. The intracellular concentration of Zn2+ and Mg2+ remained the same as for stationary phase cells, and Ni2+, Mo2+ and Co2+ were expelled from the cell during lag phase. Metal homeostasis was determined to be a critical process, highlighted by growth in the presence of a chelator causing an extended lag time. Overall, lag phase was found to be a robust and reproducible adaptation period which was not perturbed by the mutagenesis approaches utilised in this study

Investigation of Diode Pumped Alkali Laser Atmospheric Transmission Using Tunable Diode Laser Absorption Spectroscopy

A field deployable, tunable diode laser absorption spectroscopy (TDLAS) device fiber coupled to a pair of 12.5 Ritchey-Chretien telescopes was used to study atmospheric propagation for open path lengths of 100 m to 1,000 m to estimate atmospheric transmission at key High Energy Laser (HEL) wavelengths. The potassium (K) version of the Diode Pumped Alkali Laser (DPAL) operates in between two of the sharp oxygen rotational features in the PP and the PQ branches. Initial experiments were performed in the vicinity of molecular oxygen X3Σ-g to b1Σ+g electronic transition lines near the potassium emission line at 770 nm. More than 50 rotational lines in the molecular oxygen A-band X3Σ-g to b1Σ+g transition near 760 nm were observed. Temperatures were determined from the Boltzmann rotational distribution to within 1.3% (less than 2 K). Oxygen concentration was obtained from the integrated spectral area of the absorption features to within 1.6% (less than 0.04 x 1018 molecules / cm3). Pressure was determined independently from the pressure-broadened Voigt lineshapes to within 10%

From antiangiogenesis to hypoxia: current research and future directions

Angiogenesis has long been recognized as an essential element in tumor growth. Since the conception of antiangiogenesis for cancer therapeutics, great strides have been made in understanding the molecular biology underlying angiogenesis, both in cancer and in physiology. By capitalizing on these advancements through bench-to-bedside research, potent antiangiogenic agents have been developed and tested. To date, the clinical results of most of these antiangiogenic agents have not met expectations. Even with the most successful agents, such as bevacizumab, used either as single agents or in combination with chemotherapy, gains in overall survival of cancer patients have been modest in most cases. In this article, the authors present the evolving views of antiangiogenic therapy, review recent experimental and clinical studies on antiangiogenesis, and address the fundamental role of hypoxia in tumor progression, which may be key to improving the efficacy of antiangiogenic therapy

Engaging Adjunct Faculty: The Role of Leadership in Faculty Development Initiatives

This interactive session will focus on issues faced by academic administrators and faculty development staff in supporting and mentoring adjunct faculty. It will review steps we have taken at our institution to engage adjunct faculty through onboarding and ongoing development activities. Three key takeaways for attendees are:(1) To learn about the benefits of effective adjunct mentorship, including improved teaching effectiveness, retention, and job-satisfaction.(2) To identify major themes for new adjunct orientation and methods for presenting these using online resources.(3) To explore best practices for supporting adjunct faculty, including synchronous and asynchronous activities. Through presentation, discussion, and hands-on activities, participants should leave the session engaged with innovative tools and strategies needed to effectively support and mentor adjunct faculty