May 27, 2015

We published a recent collaborative paper headed up by Robert Ryan's group in Dundee, Scotland. Chris Earl, a graduate student in the Ryan lab, who spent several months in my group as a visiting student, leads the study.  The paper, published in EMBO Molecular Medicine, is titled "Haemophilus influenzae responds to glucocorticoids used in asthma therapy by modulation of biofilm formation and antibiotic resistance". Earl, Ryan and colleagues show that treatment glucocorticoids typically used as a therapy to treat asthma patients, also impacts H. influenzae, a common component of the microbiome in asthma patients.  They found that "corticosteroid-responsive genes also showed elevated expression in H. influenzae within sputum from asthma patients undergoing steroid treatment" - thus their in vitro model seems to reflect events in the patient.  Treatment with the steroid boosts biofilm formation and enhances antimicrobial tolerance, thus likely increasing the ability of this microbe to persist in the lungs of asthma patients. A graphic accompanying the paper and showing the microbe and a steroid used in the study if shown here.

May 26, 2015

Andrea Wieck has joined us as a visiting postdoctoral fellow for the next 2-1/2 months from PUCRS - Pontifical Catholic University of Porto Alegre, Brazil.  She will be working with us on some of our polymicrobial community and microbiome work.  Welcome!

May 21, 2015

Jon Miller, a Dartmouth College undergraduate, successfully defended his honors thesis yesterday.  He did a terrific job.  His work has focused on new spacer insertion into the CRISPR system of Pseudomonas aeruginosa.  Jon will be graduating in a couple of weeks, and heading off to medical school in the fall.

May 18, 2015

Laura Filkins successfully defended her PhD thesis about a week ago.  Her work has focused on polymicrobial communities in CF - she has combined lab studies with microbiome studies using clinical samples as well as developing diagnostics to track the microbes in the CF airway.  Her work was supported by an NIH training grant, the Cystic Fibrosis Foundation and Dartmouth's Lung Biology Center.  This research has also highlighted Laura's ability to perform studies from bench to bedside.  Katherine Lemon Md, PhD from the Forsythe Institute in Boston served as Laura's outside examiner.  Katherine also gave a talk on her work studying poly-microbial interactions in the context of nasal microbial communities.  Laura will stay on as a postdoc for ~1 year before heading off to join a 2 year fellowship program for training in clinical microbiology.

May 12, 2015

Gary Heussler (left), a PhD student in the lab just published a paper titled "Clustered Regularly Interspaced Short Palindromic Repeat-Dependent, Biofilm-Specific Death of Pseudomonas aeruginosa Mediated by Increased Expression of Phage-Related Genes" in mBio.  This work follows on previous studies from our group showing that lysogeny of phage DMS3 into the P. aeruginosa genome results in loss of biofilm formation and swarming. This loss of biofilm formation and swarming requires a functional CRISPR system in P. aeruginosa.  In this report, Gary shows that the targeting of a 32 nt protospacer and the flanking PAM, inserted onto the chromosome, is necessary and sufficient to induce CRISPR-mediated loss of these group behaviors.  Gary went onto show that loss of these behaviors is due to surface-dependent death of the bacteria.  Gary's data is consistent with the model that the surface-associated killing is due to induction of the SOS response, and specifically RecA, via CRISPR-mediated nicking of the chromosome.  RecA induction results in greatly increased expression of pyocin and phage holin-like proteins when cells are on a surface - these proteins in turn mediate death of P. aeruginosa.  Gary's work suggests a non-defense role for this CRISPR system in impacting P. aeruginosa biology.

May 04, 2015

On March 31, I posted news of a collaboration collaborative report with colleagues here at Dartmouth, led by Juliette Madan (in the Dept. of Pediatrics) and Annie Hoen (in the Dept. of Epidemiology), investigating the upper airway and gut microflora of infants and children with CF. This group of children ranged up to almost 3 years of age.  A nice Commentary for this paper was written in J. Peds. by Drs. Blaser and Segal highlighting this paper.