Altruistic feeding and cell-cell signaling during bacterial differentiation actively enhance phenotypic heterogeneity.

Starvation triggers bacterial spore formation, a committed differentiation program that transforms a vegetative cell into a dormant spore. Cells in a population enter sporulation non-uniformly to secure against the possibility that favorable growth conditions, which puts sporulation-committed cells at a disadvantage, may resume. This heterogeneous behavior is initiated by a passive mechanism: stochastic activation of a master transcriptional regulator. Here, we identify a cell-cell communication pathway that actively promotes phenotypic heterogeneity, wherein Bacillus subtilis cells that start sporulating early utilize a calcineurin-like phosphoesterase to release glycerol, which simultaneously acts as a signaling molecule and a nutrient to delay non-sporulating cells from entering sporulation. This produced a more diverse population that was better poised to exploit a sudden influx of nutrients compared to those generating heterogeneity via stochastic gene expression alone. Although conflict systems are prevalent among microbes, genetically encoded cooperative behavior in unicellular organisms can evidently also boost inclusive fitness.

Chaperone Hsp70 helps Salmonella survive infection-relevant stress by reducing protein synthesis.

In all domains of life, Hsp70 chaperones preserve protein homeostasis by promoting protein folding and degradation and preventing protein aggregation. We now report that the Hsp70 from the bacterial pathogen Salmonella enterica serovar Typhimurium-termed DnaK-independently reduces protein synthesis in vitro and in S. Typhimurium facing cytoplasmic Mg2+ starvation, a condition encountered during infection. This reduction reflects a 3-fold increase in ribosome association with DnaK and a 30-fold decrease in ribosome association with trigger factor, the chaperone normally associated with translating ribosomes. Surprisingly, this reduction does not involve J-domain cochaperones, unlike previously known functions of DnaK. Removing the 74 C-terminal amino acids of the 638-residue long DnaK impeded DnaK association with ribosomes and reduction of protein synthesis, rendering S. Typhimurium defective in protein homeostasis during cytoplasmic Mg2+ starvation. DnaK-dependent reduction in protein synthesis is critical for survival against Mg2+ starvation because inhibiting protein synthesis in a dnaK-independent manner overcame the 10,000-fold loss in viability resulting from DnaK truncation. Our results indicate that DnaK protects bacteria from infection-relevant stresses by coordinating protein synthesis with protein folding capacity.

Cellular Adaptations to Cytoplasmic Mg2+ Limitation.

Mg2+ is the most abundant divalent cation in living cells. It is essential for charge neutralization, macromolecule stabilization, and the assembly and activity of ribosomes and as a cofactor for enzymatic reactions. When experiencing low cytoplasmic Mg2+, bacteria adopt two main strategies: They increase the abundance and activity of Mg2+ importers and decrease the abundance of Mg2+-chelating ATP and rRNA. These changes reduce regulated proteolysis by ATP-dependent proteases and protein synthesis in a systemic fashion. In many bacterial species, the transcriptional regulator PhoP controls expression of proteins mediating these changes. The 5' leader region of some mRNAs responds to low cytoplasmic Mg2+ or to disruptions in translation of open reading frames in the leader regions by furthering expression of the associated coding regions, which specify proteins mediating survival when the cytoplasmic Mg2+ concentration is low. Microbial species often utilize similar adaptation strategies to cope with low cytoplasmic Mg2+ despite relying on different genes to do so.

A functional genomics screen identifying blood cell development genes in Drosophila by undergraduates participating in a course-based research experience.

Undergraduate students participating in the UCLA Undergraduate Research Consortium for Functional Genomics (URCFG) have conducted a two-phased screen using RNA interference (RNAi) in combination with fluorescent reporter proteins to identify genes important for hematopoiesis in Drosophila. This screen disrupted the function of approximately 3500 genes and identified 137 candidate genes for which loss of function leads to observable changes in the hematopoietic development. Targeting RNAi to maturing, progenitor, and regulatory cell types identified key subsets that either limit or promote blood cell maturation. Bioinformatic analysis reveals gene enrichment in several previously uncharacterized areas, including RNA processing and export and vesicular trafficking. Lastly, the participation of students in this course-based undergraduate research experience (CURE) correlated with increased learning gains across several areas, as well as increased STEM retention, indicating that authentic, student-driven research in the form of a CURE represents an impactful and enriching pedagogical approach.

Retrospective analysis of pharmacist interventions in an ambulatory palliative care practice.

BACKGROUND: We have previously reported the development of an outpatient palliative care practice under pharmacist-physician collaboration. The Doris A. Howell Service at the University of California, San Diego Moores Cancer Center includes two pharmacists who participate in a transdisciplinary clinic and provide follow-up care to patients. OBJECTIVE: This study evaluated pharmacist interventions and patient outcomes of a pharmacist-led outpatient palliative care practice. METHODS: This was a retrospective data analysis conducted at a single, academic, comprehensive cancer center. New (first visit) patient consultations were referred by an oncologist or hematologist to an outpatient palliative care practice. A pharmacist evaluated the patient at the first visit and at follow-up (second, third, and fourth visits). Medication problems identified, medication changes made, and changes in pain scores were assessed. RESULTS: Eighty-four new and 135 follow-up patient visits with the pharmacist occurred from March 2011 to March 2012. All new patients (n = 80) were mostly women (n = 44), had localized disease (n = 42), a gastrointestinal cancer type (n = 21), and were on a long-acting (n = 61) and short-acting (n = 70) opioid. A lack of medication efficacy was the most common problem for symptoms of pain, constipation, and nausea/vomiting that was identified by the pharmacist at all visits. A change in pain medication dose and initiation of a new medication for constipation and nausea/vomiting were the most common interventions by the pharmacist. A statistically significant change in pain score was observed for the third visit, but not for the second and fourth visits. CONCLUSIONS: A pharmacist-led outpatient palliative care practice identified medication problems for management of pain, constipation, and nausea/vomiting. Medication changes involved a change in dose and/or initiating a new medication. Trends were observed in improvement and stabilization of pain over subsequent clinic visits.