Wednesday, Dec 21 at 1 pm ET: How bacteria affect multicellular development

How did multicellular life evolve? This is a fundamental question in biology. One way to investigate this question is to probe the developmental programs of organisms like choanoflagellates, protists that are considered the closest living relatives of animals. Some species of choanoflagellates alternate between a single-celled and a multicellular form, called a rosette. The formation of this colonial assemblage of individual choanoflagellates is prompted by cues from environmental bacteria. This system provides a fascinating glimpse into how our own microbial partners may have impacted our evolution as multicellular animals.

In this paper published earlier this year, Nicole King and her colleagues looked at one particular species of bacteria and analyzed how its lipids affect the development of rosettes. Join us on Wednesday 12/21 at 1 pm ET as we talk choanos, bacteria and multicellular life! (You know, just your typical holiday party topics.)

Link to paper (open access): http://www.pnas.org/content/113/28/7894.full

Link to join Hangout is here: https://hangouts.google.com/call/5n3nwj3tubbmnjud3putwlmoqee

Oct 27 @ 1pm ET: Bacteria Spearguns

Bacteria have unusual problems. Everything they create is in their cytosol compartmentalized within by their barrier membranes. They have to resolve how to deliver these components outside of the cell. If they had all the time in the world, diffusion would work. But what if delivery had to be really fast, like handing someone some thing traveling by at top speed in a split second?

Bacteria resolve this issue through power ranger megazord-like protein nanomachines called secretion systems. These massive multi-component protein complexes assemble to deliver proteins, DNA, and small molecules across membranes. One type of secretion system, the speargun resembling Type 6 secretion system (T6SS, creatively named by the order of discovery), has starred in many unusual bacterial findings. This month, we’ll discuss a brand new paper on bacteria cooperating by sharing and recycling T6SS components between neighboring cells. How do they do this? Join us on Oct 27th to find out!

Join us for the hangout!
https://hangouts.google.com/call/dzpmzje6mnauxd2bkjab7kyimue

Or (lurk) watch on YouTube Live! link:

Paper Abstract:

http://dx.doi.org/10.1016/j.cell.2016.08.023

Link to the paper:

Type VI Secretion System Substrates Are Transferred and Reused among Sister Cells

Supplemental Information

May 18 at 3 pm ET: a minimal genome for cellular life

What are the essential components for cellular life? Which pathways and gene products are required, and which are dispensable or redundant? Of course, “essential” and “dispensable” are context-dependent terms, but it can be a useful exercise to break a cellular organism down to the minimal blueprint needed for viability. In March of this year, a team of scientists from multiple institutions tinkered with a synthetic Mycoplasma genome to construct a severely reduced genome capable of supporting a viable cell. This 531 kb genome had 473 genes, including 149 genes of unknown function. On Wednesday, May 18, we’ll talk about the construction of this minimal bacterial genome, the concept of “quasi-essential” genes, and genes of unknown function. The big question, as my students are fond of saying, is “What is life?!”

All are welcome to join us! We are always glad for new people to hop in to the discussion. Click the following link to join the Hangout: https://hangouts.google.com/call/xlbyxxzdgrdghbhhxunnfazrkue

Because this paper relies heavily on a 2010 paper describing the construction of the synthetic genome, I’ll include links to both papers.

2016 minimal bacterial genome: http://science.sciencemag.org/content/351/6280/aad6253.full

2010 synthetic genome: http://science.sciencemag.org/content/329/5987/52.full

 

April 25 at 3 pm ET: Barriers to genetic exchange in Myxococcus

The study of social behavior and self recognition in bacteria gives us a fascinating view into the complex social lives of these single-celled organisms. The bacterium Myxococcus xanthus exhibits a range of social behaviors, including predation on other bacteria and the formation of multicellular fruiting bodies under starvation conditions. In this paper, the authors explore genomic divergence in Myxococcus strains isolated from the same small patch of soil and present evidence of a barrier to genetic exchange. What does this mean for self/non-self discrimination in Myxococcus? Is this the beginnings of a speciation event? Join us April 25 at 3 pm to discuss! All are welcome.

Link to join our Hangout: https://hangouts.google.com/call/pgee576tfjeczi4f4fwl4ox4iie We are delighted to have new people join us. The more, the merrier!

Link to paper (open access): http://www.nature.com/ismej/journal/vaop/ncurrent/full/ismej201634a.html

 

March 28 at 3pm ET: Evolution of obligate mutualists in stink bugs

Bacterial relationships with their hosts have been catapulted into the spotlight with the recent explosion of microbiome research. In theory, before becoming a vital part of their host, microbiome members were once a part of the environment. How did they evolve from a state of independence into embracing interdependence? A group recently published their insights on this question in Nature Microbiology, using an unlikely system: The stink bug and its ‘bugs’. This paper might be about smelly bugs, but their results are sweet.

Join us for journal club on March 28th at 3PM EST! As always, all are welcome. Here’s the link to join: https://hangouts.google.com/?action=call&id=7c6zqv63wvgjdg57wysuhyeipym

Link to the paper:

Obligate bacterial mutualists evolving from environmental bacteria in natural insect populations

Supplementary Information

 

February 22 at 3 pm ET: Atypical E. coli pathogenicity islands

‘Atypical’ is not a term you would expect to describe pathogenic E. coli. In this case, ‘atypical’ refers to E. coli that are missing certain – you guessed it – typical pathogenic E. coli genes. While different, both E. coli types share the locus of enterocyte effacement (LEE) – a collection of pathogenic genes – also known as a pathogenicity island. We’ll discuss more about atypical traits as we look at a brand new paper from Kathryn Holt’s group on atypical pathogenic E. coli LEE pathogenicity island variants. Holt’s team compares LEEs across ~200 atypical isolates collected around the world. Through their data, they trace the bacteria’s evolution and come to some fascinating and unexpected conclusions.

Join us for journal club on February 22nd at 3pm ET! Everyone is welcome. Here’s the link to join the hangout: https://hangouts.google.com/call/skb3bl6gyjbp5chkfilehn2rsea

Link to the paper:

Evolution of atypical enteropathogenic E. coli by repeated acquisition of LEE pathogenicity island variants

Supplemental Info

Supplemental Table 1

January 25 at 3 pm ET: Cpf1 and CRISPR-Cas systems

CRISPR-Cas systems are found in many bacteria and archaea, and they act as an immune system to defend host cells from foreign DNA elements like plasmids and bacteriophage. In this paper from late 2015, the authors demonstrate that the Cpf1 protein found in Francisella functions as an effector protein in a CRISPR-Cas system. They also explore potential applications of this particular CRISPR-Cas system for genome editing in human cell lines. CRISPR has been making the headlines recently, including as Science’s Breakthrough of the Year for 2015. Join us on Monday to delve into one piece of the CRISPR story!

All are welcome. Link to join our Hangout is here. Or, you can watch on YouTube here.

Link to article: “Cpf1 is a single RNA-guided endonuclease of a Class 2 CRISPR-Cas system”

November 10, 2015 at 2pm ET: Bacteriophage search strategies

“It is a truth universally acknowledged, that a nascent bacteriophage in possession of a good genome, must be in want of a cell to infect.”*

This parody line nicely summarizes the premise our November journal club. A group at San Diego State University recently shared their findings on the “hunting strategies” of bacteriophages. By observing and modelling bacteriophage movement, the researchers found phage can display unique ways of moving through mucus. The study raises fascinating questions like, can we use the predatory nature of microbes to combat infection? Or (as the authors propose) alter the microbiome on mucosal surfaces? Moreover, should search strategies serve as a trait for selecting phage used in therapies?

Join us on Tuesday, November 10th, at 2pm ET! All are welcome. Link to join our Hangout will be posted here at 1:45 pm ET on the day of the Hangout. Or, you can tweet us @kareynlo or @MicroWavesSci and we’ll send you the link on the day of the Hangout.

Watch on YouTube here:

Link to article:
“Subdiffusive motion of bacteriophage in mucosal surfaces increases the frequency of bacterial encounters”
http://www.pnas.org/content/early/2015/10/14/1508355112.abstract
paywalled – contact me on Twitter @kareynlo if you need the paper

Science press coverage:
“The phage is a lonely hunter”
http://phys.org/news/2015-10-phage-lonely-hunter.html

*The quote is parodied from the first line of Jane Austen’s “Pride and Prejudice”. Well, there are remarkable similarities between viruses hunting for a host and humans hunting for a mate, wouldn’t you say?

October 6, 2015 at 2 pm ET: Metagenomic data and bacterial growth dynamics

October 6, 2015 at 2 pm ET
In a recent issue of Science, a group of researchers explored how to mine metagenomic data from gut microbial communities to understand bacterial growth dynamics in the gut. With this information, we may be able to expand our view of the microbiome from who is there and what functions they perform to include how the population size of different microbes change in response to environmental cues. This type of analysis may be able to help us understand the dynamics of different disease states.

Join us on Tuesday, October 6 for our first journal club of fall 2015! All are welcome.
Link to join our Hangout will be posted here at 1:45 pm ET on the day of the Hangout. Or, you can tweet me @MicroWavesSci and I’ll send you the link on the day of the Hangout.

Watch on YouTube here:

Link to article:
https://www.sciencemag.org/content/349/6252/1101.full
paywalled – please contact me on Twitter @MicroWavesSci if you need a PDF

Perspective on the article by Julie Segre:
https://www.sciencemag.org/content/349/6252/1058.full
may also be paywalled – please contact me on Twitter @MicroWavesSci if you need a PDF

April 28, 2015 at 2 pm ET: Evolutionary pathways

April 28, 2015 at 2 pm ET
In a study published in the open access journal eLife in late March, a group of researchers investigated the evolutionary pathways leading to the ‘wrinkly spreader’ morph of Pseudomonas fluorescens. By removing the three mutational pathways previously observed, the researchers tested whether alternative evolutionary pathways are available. This model system allowed the researchers to explore the constraints that favor certain evolutionary pathways to a phenotype. Broadly, the outcomes of this research contribute to the development of a set of principles or rules that will allow us to make more accurate predictions about bacterial evolution, such as the evolution of antibiotic resistance.

Join us on Tuesday, April 28 at 2 pm ET to talk Pseudomonas, experimental evolution and genetics! All are welcome. Link to join the Hangout On Air will be posted here on the day of the journal club: https://plus.google.com/hangouts/_/hoaevent/AP36tYc2Nw_utV_C2H2CZ_XvWL8JQLI_rGpseDS20ZMOX9a5Pjyr8A

Or you can watch live or later on YouTube here:

Article: http://elifesciences.org/content/4/e07074