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Showing posts from 2014

Native microbiome of Anopheles impedes transmission of Wolbachia

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In an Early Edition PNAS article published this week, Jason Rasgon and friends (with Grant Hughes as first author) publish an elegant  set of experiments, the provocative results of which lead us to the conclusion: "THE MICROBIOME IS F-ING RESPONSIBLE FOR EVERYTHING"   Honestly folks, is there one f-ing thing to which the microbiome does not contribute?  Let's dive into this article, as it is some of the most interesting work I've seen on Wolbachia with direct relevance to their use in vector blocking.  Oh, and if you want to read along (and have access to the PNAS site), here is the link to the article.

Some background first.  Wolbachia, the alpha-proteobacterial queen of insect reproductive manipulations, is an obligately intracellular and maternally transmitted bacterium.  Various folks have been investigating it for its ability to prevent mosquitoes (and other insects) from harboring or transmitting viruses (see earlier post on this here).   Dr. Rasgon, and his l…

How sweet it is: metatranscriptomics of the bacterial community within the honey bee gut

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My student, Fredrick ("Freddy") Lee, published his first research paper in Environmental Microbiology this month.  Our lab's been focusing a lot recently on the honey bee microbiome and metabolic function of the community in situ.  In this manuscript (titled: Saccharide breakdown and fermentation by the honey bee gut microbiome), we explore the capabilities of the honey bee gut community using RNA sequencing.  We also tested the effect of some commonly used enrichment protocols (the MICROBEnrich kit from life technologies) in the pipeline Freddy used to process the bee samples.  Using three individual bees, he extracted total RNA and also used the aforementioned kit.  We made 100 cycle PE libraries for an Illumina GA IIx.  Here are the highlights:

Major bacterial phyla and classes identified using 16s rRNA gene mining

We used blast to map high quality short reads to our well known honey bee taxonomy and found that, like our previous studies, these transcriptomes are domin…

Wolbachia Variants Induce Differential Protection to Viruses in Drosophila melanogaster

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A truly awesome paper on Wolbachia, variation in the pathogen-blocking phenotype, and genetics was published a while back by Luis Teixeira's group.  I've been eager to write a blog post on this particular paper, one of my favorite papers from 2013, so here goes!  
<Follow along with the paper here.>

You are reading this blog, so maybe you don't need convincing that Wolbachia are totally awesome, relevant, and interesting bacteria.  They infect about half of the insect species on the planet and do so by targeting the germ line: that's right folks, these babies come pre-loaded with their bacterial symbiont.  Recently, Wolbachia have become more medically relevant because folks (including Texieira himself with Michael Ashburner) found out that they protect their insect hosts from virus infection -- either by reducing the load that the host carries (resistance) or by preventing disease even if the virus replicates (tolerance).  However, different Wolbachia strains vary…

Tunes for the post-reviewer blues

Whether you are reading a review of a grant application or that infamous "reviewer #3's" response to your manuscript, rejection can be tough to handle.  Listening to music may be able to help you cope with this stressful event <see research on this phenomenon here>, perhaps enough to get you past this submission cycle with enough cojones for the next.  Here are some suggestions, take 'em or leave 'em:

Phase 1: Denial and depression - no way, it can't be

 "Better Man" by Pearl Jam.
Can't find a better man. You're stuck in this.

 "Black" by Pearl Jam.
Just so obviously appropriate.  Although maybe love song for NIH/NSF. "Yeah.  I know someday you'll have a beautiful life . I know you'll be a star. In somebody else's sky. But why. Why. Why can't it be. Why can't it be mine."  Why can't that $$ be mine...


"Mr. Self Destruct" by Nine Inch Nails
I bring you the 90's Trent Reznor, sigh,…

What's the DEal? Differential Expression using RSEM

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We've been looking for ways to analyze transcriptomes correctly, with sufficient power, not too many type I and II errors, and not much fuss.  For those relatively unfamiliar with performing differential expression analyses on RNA-seq data, a great review of the statistical methods employed to analyze these data can be found here.

What it all comes down to is the fundamental problem associated with RNA seq experiments -- the absence of a single transcript could be due to down regulation OR, could be due to the up regulation of ANOTHER gene.  That's right, what you are measuring are RELATIVE expression levels, and given libraries of the same size, you cannot accurately distinguish the first scenario from the second unless you've spiked the libraries with some standards of known quantity (which, interestingly enough, has been done before with success by Mary Ann Moran's group here).

From Mary Ann Moran's paper on the subject, we have this very nice depiction of the …

How does an obligately intracellular symbiont maintain genetic diversity? The Wolbachia story

I recently had the pleasure of finally sitting down to read some publications (both open access!) on my favorite bacterium, Wolbachia pipientis.  These recent pubs interested me because they focused on the population genetics of Wolbachia within individual hosts, upon host transfer, and after many generations.  The BIG question that comes out of this body of work, in my mind, is how are low-titer strains in the maternally transmitted population maintained!  (We can discuss ongoing hypotheses at the end of this post)

The first paper I'll tackle (Schneider et al) asks if Wolbachia strains exist as diverse quasi-species within a host and reveals that diversity using host transfer techniques.  In "Uncovering Wolbachia Diversity upon Artificial Host Transfer" by Schneider et al., the authors use the cherry fruit fly Wolbachia (wCer strains) as the inoculum for injection of two new hosts: Drosophila simulans or Ceratitis capitata.  For those unfamiliar with the technique, what…