TWiM 59 Letters

Oscar writes:

This is the greatest TWiM ever. (#58)

I've always been interested in evolutionary complexity and for the last seven years or so I've been unable to think of evolution in terms of traditional survival of the fittest on an individual level--at first it just seemed too simple. But through these years of rumination on the subject often provoked by a science story in the news (or on a science-ey show (radio-lab, I'm looking at you--I love you but I'm looking at you)) that approaches evolution through the perspective of survivability of the individual as opposed to survivability of a complex ecosystem of interactive life-ey things and then failing to see obvious conclusions because of this narrow view, I'm nearly unable to conceive of the idea of an 'individual' organism having any meaningful impact on (even short term) evolution.

This episode of TWiM starts with Elio giving a very masterful explanation of the paper: Underground Mycelial Networks Carry Warning Signals to Plants. His gentle and thorough description makes me long for an opportunity to attend a lecture class with him. He is truly a masterful lecturer with managed digressions that are interesting and make it clear that he is processing the information further as he speaks making the reality of hearing a brain (or brain-biome) at the top of its performance and with such great depth of knowledge really tangible and exciting.

Of course the content of that paper is also remarkable and Vincent and Michael do spectacular jobs of interjecting and referring to relevant information as well as questioning things where it's due. The dynamic in this episode is really great.

Then to top it off the second paper about the Brain Microbiome is as amazing as the first paper. During the discussion of this paper one can really feel the excitement and disbelief from the trio as they consider the implications of how this can change our understanding of the brain. I'd like to add that I wasn't at all surprised by the fact that our brain has it's own microbiome (I actually was a little surprised that it wasn't a foregone conclusion).

This episode was truly enlightening and highly entertaining. I was so riveted to the entire thing--I felt like that's what witnessing the moon-landing for the first time must have been like--it's real discovery and really cool.

So thanks TWiM guys and keep up the work. I don't care if you don't produce an episode every week, just get them out occasionally because this is important stuff that people need to know.

Finally: I'd just like to throw this out there: I'm at the point now where when I seriously think of how things evolve, all pieces of a system have to be taken into an account. It's easiest for me to grok if I consider a physical space and all of the life and non-life inside it and then also to consider a significant time-period that must include thousands if not millions of generations of changes and co-dependencies that have developed and curated. I know life has evolved to evolve (I can give a number of examples of that) and I know life has evolved to evolve to evolve (I even have a couple of that) the next level isn't easy to see but I guarantee it's there and it probably recurrses an innumerable amount of times in ways that are both simple and complex and we just have yet to understand.

I'll leave you with this: Despite the appearance of randomness guiding the evolution of the beaks on Darwin's finches I promise that the beaks of those finches have evolved to have high-rates of randomization and likely even environmental influences that either magnify or reduce the amount of randomness that's displayed--after all, evolving a trait that helps them evolve will increase survivability and that's the meaning of life.

Thanks for the great TWiM!

Oscar Prill
Technology Director
Lionsgate Academy

Mark writes:

Hi Vincent et al
I have been listening to TWiM for several weeks after moving to a new job that requires me to undertake a one-hour drive to work. I enjoy the show very much: in fact, I enjoy it so much that I am thinking of setting up a similar podcast this side of the Atlantic.

But this is not the reason I am writing.

I listened to your discussion of the brain microbiome this week. And, even though I note the question mark in your title after the term "brain microbiome", I think you were not skeptical enough.

OK, I admit that the paper presents an internally consistent story. But they don't report trying to grow the bacteria. And, rather than one organism, they would have us believe there is a kitchen sink's worth of microbes in these brains. Remember when we look at most sterile samples, we assume that a mixed growth equals contamination! And alpha-proteobacteria are common contaminants of water supplies, even in the International Space Station!

But more generally, as Carl Sagan put it, extraordinary claims require extraordinary evidence! And IMHO the evidence presented here is not compelling enough to overturn over a century of microbiology and histopathology. If these bacteria are really there, would we not have seen them already? If we look at precedents, we could be looking at the next Helicobacter pylori and these authors are going to be Nobel laureates. But I think a more plausible precedent is XMRV or arsenic life, both of which turned out to be nonsense. Go take a look at Ioniddis' paper "Why most published research findings are false"

Only time and attempts at independent replication will tell what is going on here. But I am prepared to wager that in ten years time this paper will have been discredited or forgotten.

Keep up the good work!


Professor Mark Pallen
Professor of Microbial Genomics and
Head of the Division of Microbiology and Infection
Warwick Medical School
University of Warwick

Robin writes:

TWiM #58: The brain microbiome

The brain microbiome would have been outright heresy in the latter 1960s when I had medical microbiology in med school. Today's facts are stranger than the wildest imaginable fiction of a bygone era.

Both papers go to show the enormously complex interconnectedness of all things.

The idea of signals transmitted through a network of mycorrhiza suggests a slow intelligence with signals acting over hours or days instead of milliseconds as is the case with neurones. An awareness associated with such an intelligence would have little commonality with what is familiar to us. Even though chemical inputs equivalent to smell and taste, mechanical inputs equivalent to hearing and touch, and light inputs equivalent to vision could affect such a system, they would be so different that it may be impossible to form a concept of such awareness.

It is to be noted that in Eastern traditions, awareness is consciousness with content; appropriately organised complex configurations of matter and energy will manifest awareness just as non-magnetic pieces of iron in a magnetic field will manifest magnetism.

Methyl salicylate is present in large quantities in oil of wintergreen: even a teaspoon if ingested can cause severe salicylate toxicity. Aspirin is acetylsalicylic acid. It is less irritating and less toxic than methyl salicylate. The intrinsic stickiness of blood platelets depends on platelet cyclooxygenase, which is inactivated by acetylation by acetylsalicylic acid. A single tablet of aspirin will inactivate the platelet cyclooxygenase in all the platelets. It also affects the other blood cells, but unlike platelets, they regenerate their cyclooxygenase. Platelets have to be replaced by newly formed platelets. Since platelets have a lifespan of seven days, a tablet of aspirin is good for two to three days.

Eli writes:

Hi Vincent et al!

I was listening to the TWIM episode #55: In the copper room, about bringing down hospital infections.

You mentioned two things as being the main problem. The first one was high occupancy rate.

Quote from the episode:

"The second and this is probably the most important reason, is that you can't tell that things are dirty - from a microbial perspective. And we don't routinely survey the area to ask what is the microbial load"

I am thinking, what if the bacterias could somehow be made visible. It would be real cool if material could be engineered to change color to show if there is a high level of bacterias and other pathogens, to alert that a surface needs to be cleaned. It doesn't necessarily need to be visible to the naked eye, but just if some special lights got shined on it. I have no idea if it will be possible, I just liked the thought.

As you say, the main problem about hospital infections, is that the problem is invisible. And if things are invisible to our eyes, it is harder to shine mental light on it, because we don't directly get reminded about it on a daily basis. Hereby my wish for "bug luminol" is passed on.

Joe writes:

Hi guys

I really enjoyed the discussion of PULs on the most recent episode of TWIM. I had a minor correction with respect to the discussion of the connection between diet and IBD. During the discussion, one of you talked about a progression from ulcerative colitis to Crohn’s disease. In fact – these diseases, although categorized as inflammatory bowel diseases, have fairly different (albeit poorly understood) etiologies. UC is generally restricted to the colon while CD can be localized anywhere between the mouth and anus. Also, IBD patients generally have one or the other – but not both. They don’t really progress from one to the other in any individual patient.

Keep up the great discussions of the wonderful world of bacteria and human health.


Joseph McPhee Ph.D.
Michael G. DeGroote Post-Doctoral Fellow
Coombes Laboratory
McMaster University, Department of Biochemistry and Biomedical Sciences

Dave writes:

Most interesting talks on copper in disease transmission reduction environments. How about silver?

I possess several pairs of army socks (literally), a percentage of the fibers (3%? 12%?) woven into which are microcoated (or embedded, or something) with silver. The purpose is suppression of undesirable (potentially mission-defeating) microbes.

I believe they are effective. I believe there is some literature on the efficacy of silver, and rationale for its selection over copper. I think I've seen some ventures at explaining the mechanism, but I don't have the stuff in my head and can't go looking. Worth observing that they seem to enable wearing socks for more than one day without getting stinky.

Interesting aside: I went looking for army socks after hearing an ER doc describe managing the pain of 36 hours on his feet by wearing wool army socks. His belief was that the wool provided a sufficient secondary cushion to dampen the impact of walking all day on concrete floors (which have no give, relative to asphalt or whatever). My feet have plagued me with easily acquired aching, so I went looking. The socks, combined with placebo action, seemed to provide noteworthy reduction of discomfort. As to heat objections, which seem culturally common among us, he reported year-round use without problem. I found them entirely comfortable, probably downright insulating, when worn in Fresno summers under boots, and certainly no worse than conventional or lightweight socks, so I ratify his year-round prescription, since they're pleasantly warm in winter too. (pause for breath) Not itchy either, in this formulation, to the contrary of old complaints about wool.

Anyway, recently I went to the military/police gear store for more socks. I was disappointed not to find the familiar thick wool, but did decide to try the new blends. Some were thinner wool blends, and others blend cotton with synthetics such as lycra, I guess. I sprung for some, and was so pleased with the (quite inexpensive, relative to Walmart work socks) performance of the silver blended ones that I went back for more. This model is near knee-high, so has the benefits (for those to whom it matters) of compression as well, potentially reducing edema and whatnot.

Anyway, whatever. Much enjoy the show(s), encountered on internet radio Science360 (which you might mention sometime). Hope you find the bit on silver vs. copper interesting. Maybe it suggests a further look along the table of elements.


Tim writes:

Michael Schmidt's enthusiasm and passion for all science is always wonderful to listen to. Hearing him discuss his own work was even more of a treat. Congrats to him and his collaborators on their great work telling a fantastic and relevant story!

- Tim

Bernadeta writes:

Dear TwiM podcasters,

Thanks for another great episode! Each TwiM/P/V episode you do brings me so much inspiration and I wait impatiently for another one to come. Usually, though after each episode I have more questions than answers, which I think is great because that what science is based on, like Feynman said: science is expanding frontier of ignorance the more we know the more there is to answer.

Regarding the last episode, I always find these phage-bacteria arms races very fascinating; they are a perfect example of how evolution can work in short period of time.

On last episode it was mentioned that CRISPR/Cas system takes up DNA randomly irrespectively of whether that would come from a "helpful" or a "bad" phage. If the process is random then would it also take up DNA that was acquired through transformation or transduction?

Can Cas somehow distinguish if it's a phage DNA or not?
Is it maybe specific for some kind of base modification like hydroxymethylcytosine that are found often in phage DNA, or does DNA sequence has to be of certain size, or maybe the DNA has to be either linear or circular (but if circular then why the phage induced resistance islands do not get accidentally incorporated into the CRISPR locus)?

Can one do a BLAST search to find if the spacer sequences in CRISPR locus are exclusively from phages or sequences from other sources are also present? I know that it would probably be of no use to incorporate random sequences into the system but then I presume that there has to be a mechanisms for distinguishing where the DNA comes from?


Andy Camilli writes:

As far as we know, the capture system is random. The phage CRISPR/Cas even occasionally captures a piece of its own genome, which is a big mistake, because it will then degrade its own DNA! What we find in these instances, is that points mutations have arisen, either in the spacer or in the target in the phage genome, that abrogate hybridization of the crRNA and thus degradation is prevented. Presumably, these mutations are selected for rather quickly.

-Dr. Camilli

Charlotte writes:

Re: ASM Discussion - I wonder how much journal's biases against publishing negative results contributes to misconduct.

Peter writes:

Hi TWiM team
I hope you were able to see the Google tribute to Julius Richard Petri:

Not sure about the streaking technique shown in the doodle though.

Jim writes:

Dr R:

This is old on uTube, but new to me. Can I suggest it as a listener's pick. Surely a similar dance be created from all the fields your podcasts represent!

I heard about the dance from class 129 by Dr. Gerald Cizadlo. His engaging manner is somewhat like yours and just this year he began offering an online version of this class, Bio 3020.


Smithfield, VA

Jim writes:

Hi Y'all,

Dr Schmidt, on TWIM 35, after the 2012 ASM conference, you mentioned use of the Quartzy networking cards at many poster sessions. Did you see the cards used this year, were they more prevalent (3,300 used last year), and were poster sessions as plentiful as last year? Have the cards stimulated any competitors?


Jim Vandiver
Smithfield, VA

PS: TWIM 56 at the ASM was awesome, just awesome! It's like listening in on a discussion between Einstein, Edison and Feynman.

Peter writes:

Dear TWiM team
I see that the Oregon Senate approved a bill establishing brewer's yeast, Saccharomyces cerevisiae as Oregon's official state microbe.

I can understand the popularity of brewers yeast, what other microbes do you think could be chosen as official state microbes?

I think food and drink related microbes would be favoured by most people so various species of Lactobacillus may be popular.

On that subject I see that there is a paper on microbiological profiles of ŞALGAM, the Turkish lactic acid fermented turnip and black carrot drink:

It is a popular drink in Turkey but rather an acquired taste for those unfamiliar with it.


Jacob writes:

Hi all,
My Dad sent me this article after I sent him a link to your episode on biospeleology.
It's about biofilm sheets in underwater caves under the Australian desert that glitter in the torchlight due to calcite crystals that are formed in the biofilm.

Jim writes:


Here's a link to a Maker site that discusses how to do a 3D print of your brain.

Smithfield, VA


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