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mailboxTWiM regularly receives listener email with corrections, comments, suggestions for show topics, requests for clarification, and additional information. A selection of these is archived on this page.

TWiM 148 Letters

Sol writes:

Oh I hope I win!
I love your podcast...
I listen to all these kind of science podcasts.
Like are we there yet? Planetary radio, star talk, science Friday, etc

Dale writes:

Hi TWIM Team
I am a graduate student of medical microbiology in Port Elizabeth, South Africa.
At the moment I study antimicrobial resistance in hospital acquired infections.
I love listening to TWIM as I do my lab work. It keeps me updated, entertained, and hearing about all the amazing articles you discuss really inspires me to continue into research!
I love books and it would be awesome to add the Colour Atlas to my growing library.
Fingers crossed and thank you for all the great content you guys produce!
Kind regards,

Sabrina writes:

Dear TWIM crew,
I was SO late listening to this podcast so I know I missed the color atlas, but alas I will try anyway (there is probably already a new contest afoot).

I am a clinical laboratory scientist in central Florida and your series of podcasts were actually what triggered me to go back to school to get my license to work in the clinical lab.

Keep up the good work!

Melissa writes:

Hi TWIM team,

I can't remember if you've already discussed this video on the TWiM, but Harvard Medical School released a timelapse video by the Kishony Lab showing bacteria adapting to the various concentrations of antibiotic on a giant agar plate with different concentrations of antibiotic.

We're all looking forward to listening to more of your podcasts!  We (Pride Lab) listen to your podcasts while we work.

University of California, San Diego

Johnye writes:

The 2nd paper about arbitrium highlighted gaps in my knowledge and left me with unanswered questions. In fact, I needed to relisten to segments of the discussions multiple times to be clear about what I didn’t understand. May I have a review of some terms and techniques?
Making “conditioned medium” is a new term for me. Is it media that has had bacteria grown in it? How long does bacteria need to be grown to be considered “conditioned”?
What is the significance; when and why is it used?
Could you please review the significance/function of “open reading frames and end terminal peptides”; “noncoding regions” ?
Also the terms:
“Helix turn helix motif “?
“Chip sequencing”?
were new to me. Could you or your co-hosts give some background and context for those terms/techniques/uses?
And “quorum sensing” makes sense to me. Is it correct to think of it as describing a population’s behavior (growth, genetic expression) based on its own density and resources available to support its viability?
Hope my knowledge gaps are not too basic and elementary. I really became concerned when Prof Schmidt’s suggested there was a good follow-up project appropriate high school project (or was that meant for the first paper)!
As always, warmest wishes (especially at this time of year on the east coast) and many thanks. Johnye
Johnye Ballenger

TWiM 147 Letters

Kala writes:

Dear Micro Crew,

Hello from frozen Ireland, it's 5 degrees Celsius but feels like -2, cloudy and generally miserable haha

I was wondering if you could give me some advice as I am stuck between a microbe and a hard place!

I have a BSc in Microbiology and 2 years experience working in a diagnostics lab, but I want go back to academia.

Microbiology is my passion and my lifetime love and I couldn't imagine being in any other profession. I have been toying with the idea of doing a masters in either marine microbiology or just straight marine biology. I have read up on both but I can't seem to decide which one would be better career wise.

The marine microbiology course is in the Max Planck institute in Bremen, Germany. And the marine biology course is in University College Cork in Ireland (my home town), this is the one that's really getting me as if I did a masters in marine biology could I apply it to my microbiology degree, and how could I do that?

My question is, do you have any idea what the career prospects would be like for either, and in my position, which would you choose?

I love your podcasts, and because of them I have just signed up as a contributing member to the American Society for Microbiology, bought a subscription for Curiosity stream and looking into attending this year's conferences XD.

Thanks for all the hard work ye put into making these wonderful education tools.

Kind regards,



Johannes writes:

Greetings from the bench in Perth Australia where it is unusually wet for this time of year.

We work on fungal infections of legumes, trying to identify fungal effector proteins. This involves a lot of cloning and screening of candidates.



Erik writes:

Hi all! Thanks again for another great episode in twim #144. Your discussions are always fun to listen to and motivate me to read more on your chosen topics. I recently picked up two books recommended on the podcast, from our library. 'Coral Reefs in the Microbial Seas' and 'Microbes and Evolution, the World that Darwin Never Saw.' I really enjoy your recommendations. It appears that I am the first person to check these two books out...which is a shame. Anyway thanks for what you do and for making my kids think I'm a Superdad because of your topics I bring up at the dinner table.

Oh and I am confused as to whether or not I should continue to use the 'cold tap  temp' water for our laundry?!? I thought I was saving energy but…



Central Mass

16 F sunny but snow on the way

: )


Tim writes:

Good morning TWIM hosts,

I've been so far behind on listening to my science podcast playlist lately that I haven't been able to try to win any of these awesome books you've been giving away or reply to TWIP case studies without being woefully late to the party. I blame Roman Mars and his 99% invisible podcast which my brother told me about and I then proceeded to listen to the entire back catalogue of. Have a great day and keep up the great work.


Brandon writes:

Although at this point I'm sure I won't be the winner I figured I may as well add something. I am an undergrad in my final semester as a biology major in Colorado while also working at a tissue bank. I love your podcasts!

Brandon, Denver Colorado


Wytamma writes:

Hi TWIM Team,

Thanks for all the great podcasts, they get my through the long hours in the turtle facility.




Anthony writes:

Persisters carrying on the genomic line?  Seed bank in SciFi flicks?  Microbial way of preserving the species?

Perhaps the intention, motivation and foresight is a bit much to expect from bacteria.

I've just taken a quick look at the Lewis paper

that was mentioned and this

from 2013.  My impression is that persister cells are dormant in response to stress, e.g. toxins.



Michael writes:

Hi all,

My name is Michael from Atlanta, GA. I don't remember if TWIM does weather, but if it matters, it is 21 C with clear skies- pretty nice for October. My reason for writing is that I just finished reading a book that I think would make for interesting discussion. It is called, "Living at Micro Scale - The unexpected physics of being small," by David Dusenbery. The book caught my eye because i am a Civil/ Environmental engineer who happens to like reading about biology in my free time. It is a nice combination of the two.

The book explores questions about how microbes' behavior is determined by the physics at different size scales. Examples are: At what size does using energy to swim make sense compared to the option of drifting under brownian motion to find food?  What body shapes are most effective for movement through water at different sizes (not intuitive)? Can the physics of small scale movement tell us why many organisms differentiate large female and small male gametes?

He goes through each topic with some rough calculations using fluid mechanics, thermo, etc to make predictions, then compares that to known data on different microbe species. I don't know if TWIM has addressed this sort of thing in the past, but if not I think it would make a fun conversation.

Thanks for all of the work you do making these shows,



Seweryn writes:

To the wonderful TWiM crew,

Last week's (TWIM #144) topic of phage-induced nuclear-like membranes was absolutely fascinating. Coincidentally as I was listening to the episode, I came across a news story about the detection of nuclear-pore like structures in the compartment of a bacterium, and thought that it would be a great followup article to discuss:

The idea of the evolutionary line between pro and eukaryotes being blurred by things that we had no idea about because no one has looked/thought outside the dogma box is really exciting - perhaps a good topic for TWiEvo?

Keep up the great work educating and entertaining the masses.



Brisbane, Australia

Head of Research, Queensland Paediatric Infectious Diseases Laboratory


Jared writes:

Hello Wonderful Hosts,

I work at a blood bank in Oklahoma. I appreciate all the hard work that goes into all your podcasts and enjoy listening to them every week. Keep up the amazing quality and banter that make up every episode.

My Thanks,


Alex writes:

Hello TWIMmers!

I hope I'm not too late to be email #12! I got a bit backed up in my podcast feed, and just made it through this TWIM.

I've written in on other book offers (though I haven't yet won), so you may be getting tired of hearing this from me. But just in case, I wanted to thank you folks for the years of TWiM, TWiV, and TWiP (I haven't made it to TWEvo or Urban Ag. yet, but maybe in 2017...)! I'm a PhD student studying microbial pathogenesis at Wash U. in St. Louis, and so your podcasts have kept my ears and brain company through many happy hours of pipetting and tissue culture work.

We are beginning to leave behind winter here in St. Louis, with a daytime high today of 61F (16C) although it remains cloudy for now.

Thanks again for the podcasts! I look forward to hearing many more.

All the best,


TWiM 146 Letters

Jonathan writes:

Hello TWiM Team,

I'm sure it's a long shot but here's hoping for #12!

I was catching up on a SciFri podcast recently and came across this story and just had to share it with you all. (Dr. Racaniello, I think Dixon would also appreciate this but I'll leaving sharing it to your discretion.)

SciFri: Scientific Simplicity by Design

Hand-powered ultralow-cost paper centrifuge

50-cent microscope that folds like origami

Thank you all for such great work on the TWiM podcast. As an epidemiologist, I stumbled upon the TWiX series while looking for ways to stay up to date with research related to infectious diseases. I also was thrilled to find my alma mater (the University of Michigan) so strongly represented in both the TWiM and TWiV podcasts! Here's to many more podcasts from the TWiX series and lifelong learning. Thanks again! 


Anthony writes:

The widespread use of cotton clothing -- that allowed for aggressive washing, including boiling -- has been considered as a major advance in health.

The attached image of text is from here:

The Biology of Human Longevity:: Inflammation, Nutrition, and Aging in the Evolution of Lifespans

by Caleb E. Finch

Napoleon's invasion of Russia might have failed because of poor hygiene.

Evidence for Louse-Transmitted Diseases in Soldiers of Napoleon’s Grand Army in Vilnius

Tangentially, the 140F (60C) possibly scalding water temperature mentioned by Professor Schmidt is chosen to prevent Legionnaires' Disease:

Much of everyday life is to ward off the pathology of everyday life.

On a separate note, here's something of possible interest for This Week in Insects:

Thank you.

Steve writes:

Hi Microphileaceae,

I happened across the above report of unfortunate Armenian folk being poisoned by botulinum toxin in 'homemade marinade', and was prompted to read more about the wondrous toxin and its bacterial producers.

I was astonished to see that this tiny, soil-living, organism, has managed to evolve toxins that interfere with a single neurotransmitter pathway of higher animals, in no fewer than seven different ways!

I know we aren't supposed to ask 'why' questions, but what on Earth (or in earth) does a soil-dwelling bacterium need with such a powerful and precisely targeted toxin against the nerves of creatures it would normally never meet? It is noted that the bacterium only produces the toxin whilst it is sporulating, so it can't be taken as a simple deterrant weapon against bacteria-eating worms.

I'd be interested to hear what the experts think as to how this particular bacterium, came to evolve such precision guided attack‎ weapons against higher animals. What do the bacteria gain by producing chemicals that attack nerve transmission in seven different ways?

Or is it just accidentally acquired genes evolving with a purpose of their own...


All the best,


Luton, England

Where the weather is, currently, nicely sunny, and very mild by your standards.

Some entries in book give-away:

Mike writes:

I love microbes. I really do! Even if I don't win the book though, I love the podcast and look forward to many more in the new year. Thank you for everything you guys do.



Erik writes:

Second entry, sorry. For my first entry I took it literally when you said send an email with the subject line 'I love microbes.' This entry I'm including a little thank you. I'm a water treatment operator who is entertained endlessly by your podcasts. Thank you all for what you do!

James writes:

Hey everyone,

Just found you all a year or so ago. Really enjoy listening despite much of the content being over my head.

I was a biology and chemistry double major at Southwestern University in Georgetown, Tx (graduated in 1987) and studied under Dr Vicente Villa and Dr Robert Soulen... both amazing professors. I was accepted to a Biology PhD program at Texas A&M but left after a semester to work in the Pharma world on the sales side.

I always loved microbiology and virology and was lucky enough to sell many antibiotics as well as a few antivirals. I always felt like I was teaching the doctors I called on a little bit more about those topics, it was a great career while it lasted (through 2013)!

Listening to your podcast helps me to feel current and still plugged in to that part of the medical and scientific community!

Thanks for all you guys do. Btw I just started listening to TWiP as well! Great job to you all!


Round Rock, Tx

Sean writes:

Hi TWIM Member’s,

Thank you for all your great work. We would use your new manuscript everyday here in our lab.



Sean E. Dunn ASCP(MB)

Arizona Department of Health Services

Public Health Scientist II

“The pure culture is the foundation for all research on infectious disease”. –Robert Koch

Gavin writes:

Hello TWIM folk,

I’m throwing my hat in the ring for the Manual of Clinical Microbiology. Also, I’ve noticed that a lot of listeners have suggested an insect podcast (an arthropodcast?). While this would be interesting, I’d like to put my two cents in and join the chorus of listeners who want more immunology. Audioimmunity hasn’t done anything since September. Thanks again for all the hard work.



Melissa writes:

I would love to receive a copy of the Manual of Microbiology to share with the lab at UCSD (crossing my fingers to be #19).

I've been listening to your podcasts since Dr. Pride introduced me to them when you spoke with him and Dr. Rohwer in TWiV. (I downloaded all of your old podcasts too and am now currently almost completely up to date in all of your podcast stations.)

Thank you for making these podcasts and keep it up. I really enjoy them all, especially TWiP.

Thank you,

Melissa Ly

from Dr. Pride's lab at UCSD

Victor writes:

Howdy y'all,

I am an avid listener and fan of the whole twix nation (not sure if that is spelled correctly). I average a hour commute each day on my commute from Cedar Park Tx to Austin Tx and am often times delighted to have a new podcast to listen to during the arduous journey.

I want to thank everyone for their time and effort they put into the podcast. Listening to Twip has helped me to discover that I want to pursue a career in medicine, specifically immunology.

I am wondering: would it be possible to have a podcast that talked about the clinical aspects of bacteria and viruses? I have a degree in Biology, with an emphasis in microbiology, and I was always interested in the clinical nature of microbes. You could even have a case study in the podcast, like twip. Just an idea.



Emory writes:

Hello Twim Team!

Thanks for all that you do, hope I'm lucky number 12.

I listen to all the Twix (just added Twevo) and am a Pediatric Nurse Practitioner. Thanks for making this science accessible.

(Holding the impulse to send 11 other emails to up my chances)



Scott writes:

Hello TWiM!

Sending this email with hopes of winning the Color Atlas of Medical Bacteriology. Listener for a few months now. Although current research opportunities has pushed me out of the lab and directed me towards the clinical field, thank you for keeping me connected to the ever-so fascinating world of microbiology.

Sean writes:


Your podcast is awesome and has encouraged me to read more papers in my spare time. I've been sharing your podcast with my colleagues. Thank you and your team for all your hard work.

Marc writes:

An unqualified listener, but love your show.

You all work in a fascinating domain.

Regards - Marc

Jack writes:

Hey TWiMers,

I'm currently finishing up my undergraduate at UCLA and interviewing for graduate school this cycle. I just wanted to say I really enjoy your podcast, particularly during hours working in a BSC. It has been very helpful during interviews and just in general keeping up with wider microbiology world.

Best Wishes,



TWiM 144 Letters

Kayla writes:

Hey there TWIM team

I am a Veterinary Microbiologist in Cork in Ireland!

Long time listener of all the TWIX series and I love everyone of them.

I work in a diagnostic lab in cork and the only thing that gets me through the day is your podcasts and buckets of tea.

Thanks for the wonderful podcasts :)


Justin writes:

Hello TWiM crew,

I listen to all the TWiX family, but TWiM happens to be my favorite, closely followed by TWiEvo.  Here's hoping I'm #19!  Hope yinz (Pittsburgh plural of you) have a fantastic 2017!

Justin Waldern
Ph.D. Student
Belford Lab
University at Albany, SUNY

Zach writes:

Hey Twim team,

Love the podcast. Keep up the good work!


Teresa writes:

I'm sending this e-mail and hope to be the lucky recipient of the two volume book Manual of Clinical Microbiology.

I am a Pediatric Nurse Practitioner practicing in a group practice in Southern California. I subscribe to TWIM, TWIV, and TWIP.  I find all of these to be quite enjoyable and informative.

Of note, I recently attended a Pediatric conference last year and one of the Speakers was Michael E. Pickering, MD who is the Director of Rochester General Hospital Research institute and Research Professor in the Health Sciences and Technology at the Rochester Institute of Technology in Rochester, New York.  One of his lectures was "It's in the nose:   Pathogenesis and immunity".  He presented the research on the microbiome of the nasopharynx and the innate immune response there.  I know more research from his department is on going and hopefully you and your colleagues at TWIM will keep a lookout for research papers about this exciting research and it's practical application to practice guidelines for care.

Now I'm off to enjoy my sunny 58 degree weather and look forward to continued listening you podcasts.


Josh writes:

Greetings TWIMers!

I just listened to your most recent episode of TWIM (#143), and definitely want to stake my claim for the free book.

Because I don’t want to just send a blank email with only a subject, I just want to say that I’ve loved your show, and have been a dedicated listener for about a year now. I’m a graduate student in the Biochemistry, Cellular and Molecular Biology program at the Johns Hopkins School of Medicine, and I’m currently rotating in Erin Goley’s lab, which studies the biochemistry of FtsZ. I love your TWIIX series for all the interesting papers you bring up; they occasionally provide really cool papers for me to bring up in journal club.

Thanks for being awesome.


Wan writes:

Dear twimers,

I'm here to try my luck in the contest. There probably hasn't been 19 emails yet(?) but I missed the past few contests on the other twi podcasts so I'd rather send in this email sooner than later.

Thanks for hosting this really engaging podcast. It has taught me a lot of microbiology while keeping my mind engaged while working in the lab.

Look forward to an exciting twi year ahead.

Best Regards,
Wan Yi From Singapore


TWiM 143 Letters

Peter writes:

Greetings TWiM Team

Thinking about the revised estimates for the number of bacterial and human cells in the body from 10:1 to about 1:1, I was wondering what the microbiome cell to self cells ratio is for different species.

I presume that it would depend on diet with herbivores  having a higher proportion of microbial cells than omnivores and that omnivores would have a higher proportion of microbial cells than  carnivores. I would guess that the smallest gut microbiome  would belong to humming birds that exist on nectar and insects.

Has the size and diversity of the microbiomes of different species ever been investigated?


Roman writes:

Dear TWIM hosts,

Love your podcast, keep it up.

Could you give me a name or link to the sound track you use? You say it's by Ronald Jenkees, but it is still hard to find.



Intro: Remix to a Remix from his first cd, Ronald Jenkees.

Outro: Stay Crunchy from Disorganized Fun

Find them at


TWiM 142 Letters

Carole writes:

Dear Vincent and hosts of TWIM,

I am a long time listener and fan of your weekly TWIM podcasts. I really enjoyed the latest episode in which you discussed a paper by Kelly Wrighton and colleagues, and was especially happy to hear you talk about chemistry! On that note I'm writing to tell you and your listeners about a seminar series entitled the Chemistry of Microbiomes, organized by the Chemical Sciences Round Table of the National Academies of Sciences. In separate workshops the series addressed Earth, Marine and Human Microbiomes, and we were fortunate to have Kelly Wrighton speak at the Earth Microbiome seminars. The talks have been archived at . If you tune in next Wednesday, Dec. 7, you can watch the final talks of the series in the All Systems seminar to be held in Washington DC.  Listeners can email or tweet questions during the talks.

Wishing all of you happy holidays.


Mark writes:

Hi Michele

I am that rare thing, a British baseball fan (and ASM member), and I have been rooting for the Cubbies this last post-season.  On top of their amazing win, my American post-doc, Morgan Feeney, just pointed out that, in the very early 1900’s, before they were called the Cubs, the Chicago NL team were briefly called the Chicago Microbes (due most likely to Chicago’s famously bad sewage system of 120 years ago – basically the river).

Take a look at this link:

Also the attached newspaper clipping.

Best wishes!


Professor Mark J. Buttner

Head, Department of Molecular Microbiology

John Innes Centre



Supti writes:

Hello I had a question regarding specialized transduction, what are the consequences of the portion of the genome of phage which remains attached to bacterial chromosomes as a result of faulty excision? I mean does it lead to any kind of useful mutation?

Thank you


TWiM 141 Letters

Tom writes:

For the article letter about microbial batteries, I think CV refers to Capacitance times Voltage, which is stored charge. In electronics, current is abbreviated I not C.

The claim in the letter got me thinking about microbial batteries and I wrote a blog post about their theoretical capacity. They have potential!

Nancy writes:

Hello TWIM team,

Since discovering you all I have been binge listening to TWIP and TWIM. Most enjoyable to listen to the discussions and very good leavening for the mind.

The point I wish to make seems so blindingly obvious that I hesitated to write to you about protecting patients from infections in the hospital. All this hand sanitizing and of its cleaning goes on but where is the attention paid to the patients' hands?

There is no hand sanitizer offered before meals or on hand by the patients' beds. I have not seen this visiting my local hospital as patient or visitor.

Maybe I am completely wrong and this protocol is in place  but if not this is a big missing component.

Thanks for the hours and hours of fascinating knowledge.



TWiM 137 Letters

Daniel writes:

Long time listener, first time writer. It has been far too long for me to offer my sincere gratitude for the podcasts. Some years ago I was a welder working a very boring job and I managed to get through my day by listening to podcasts and lectures. These podcasts and lectures convinced me to give up my boring day job and go to the excitement of university. There I progressed in biochemistry and developed a love for science, and went on to a Masters and am now working on my pHD. You can’t imagine the excitement and fulfillment when I heard our paper was featured on your podcasts (That one about diderms and monoderms). All that work seems to have paid off and it truly feels like I am a real scientists now.

So thank you!

I feel I need to give a shout out to my pHD program. The pasteur institute has an international pHD program where they call for applicants every year and provide an amazing 3-year pHD program. This institute is probably one of the best for doing science and I couldn’t picture a better pHD. Here is a link:

As for our paper thanks for the nice overview. To address Dr. Schaechter’s comments about seeing how the systems compare between E. coli and the Negativicutes I have this for you:

First of all remember E. coli is one of the most “evolved” bacteria there is. They have a large genome and incredibly complex systems (probably not the best model system due to that, but that’s history). See attached tree (It is pretty rough, so don’t make a big deal about the deep nodes, Monoderm phyla in grey, No root so don’t pay attention to what is ancient). The Negativicutes are so extremely distant that it is amazing they posses the same systems and any genomic synteny. However with the pili (some supplemental figures in the paper) it is clearly the same system. The BAM/TAM system is drastically different and matches the more closely related Fusobacteria, and other Terrabacteria beautifully. We have a lot more to say on this story and we will have more fun articles coming months :)

Daniel Poppleton

Anthony writes:

Climate influence on Vibrio and associated human diseases during the past half-century in the coastal North Atlantic.


TWiM 136 Letters

Steve writes:

Hi Microbophiles,

Here's an interesting little historic snippet from The Lancet.
Venerable bacteria: In another interesting history of science piece, The Lancet gets bully over Koch's bovine TB samples--but not over the tragedy of him advising that this form of the pathogen was not significant for human health, and thus delayed the introduction of basic meat and milk hygiene and testing.

It seems that the good and the great nearly always put their foot in it somewhere!

All the best,


Where it has been hot and sticky for some days (and nights: most people don't have air conditioning in UK homes.).   Incidentally: how does one get black mould stains out of pillowcases? Yes: that sticky!  :/

Anthony writes:

"The plague of 1665-1666 was the last major outbreak of bubonic plague in Britain, killing nearly a quarter of London's population.
It's taken a year to confirm initial findings from a suspected Great Plague burial pit during excavation work on the Crossrail site at Liverpool Street.
About 3,500 burials have been uncovered during excavation of the site.
In Germany, molecular palaeopathologist Kirsten Bos drilled out the tooth pulp to painstakingly search for the 17th century bacteria, finally obtaining positive results from five of the 20 individuals tested from the burial pit.
"We could clearly find preserved DNA signatures in the DNA extract we made from the pulp chamber and from that we were able to determine that Yersinia pestis was circulating in that individual at the time of death," she said.
"We don't know why the Great Plague of London was the last major outbreak of plague in the UK and whether there were genetic differences in the past, those strains that were circulating in Europe to those circulating today; these are all things we're trying to address by assembling more genetic information from ancient organisms."

Steve writes:

Hi TWiM team,

Just to say thanks for your interesting discussion of the points I raised regarding uses of gut gas analysis/fingerprinting, and hand hygiene in the context of declining use of copper coinage.

One or two of my points weren't expressed very well:

I hadn't intended to convey the sense of a general increase in the spread of infectious diseases‎, but more in the increase and spread of antibiotic resistant strains. The widespread use of antibiotics and antiseptics in hand and surface cleaners has, most likely, produced the general decline in infection that the team noted, but, previously, there would have been a good deal of copper in circulation on people's hands in addition; and bacteria on the fingers would frequently be brought directly into contact with copper metal, which would kill them before they could be passed on. This may have held back the spread of antibiotic resistance.

It does strike me, that, from what I hear in your podcasts, antibiotic resistance does not have to arise denovo very frequently: it is a part of the general  variation which just needs to be selected by knocking out the‎ remainder. Also, you have noted that horizontal transfer, even between unrelated bacterial species, begins almost immediately, when they are mixed  together. Given this, it seems to me that antibiotic resistance has taken a surprising long time to spread and become a major health concern. It could be, that the metals in our environment were holding it back, until recently, when our metal pipes and handrails were replaced with plastic and plastic coatings, and we reduced our use of coins in favour of plastic cards, paper, and electronic transactions.

The second remark--about mosquito's stance on it's legs--left me puzzled as to why it wasn't understood by the team. Having spent many a night scanning my walls and ceilings for nearly invisible mozzies, that whine in one's ear, as soon as the light is turned off, and then vanish again when it's turned back on, I had become very familiar with the, two back legs in the air‎, stance of the common mosquitoes, here.

I had assumed this was a general thing among those that hold themselves at an angle to the surface, but, following your team's confusion, I checked more Google images, and see that there are, indeed, as many pictures where all six legs are used, as there are of those where the back legs are held aloft or just left loose. I don't know how many species I'm looking at though.

One could imagine that the back legs might be needed for purchase while the proboscis was penetrating the skin, but then can be relaxed as‎ grip is transferred to the proboscis itself; but those on my walls hold their back legs aloft though they are not feeding, so it seems to be a preference, or have a specific purpose.   I had speculated that the raised legs may serve as aids to sensing air currents, and so contribute to the mozzie's uncanny ability to avoid swatting hands! Possibly the stripy legs of some species could be used in signalling too.

Anyhow, I have always found this stance an interesting observation. I further note, that the same places where the mozzies land, are frequented by Pholcus 'daddy long legs' spiders, but they rarely get caught. Both the spider and the mozzie have the same habit of doing high speed push-ups on their spindly legs, from time to time. I hope it's not catching!  :)

Hope this explains my points a bit better.
Many thanks for your, always thought provoking, podcasts.

(Weather now uniformly grey, cool, and still.)

Vincent: I asked Kristen Bernard at UW-Madison:

Mosquitoes often don't use the last pair of legs, but will use all six for balance especially once blood fed.


TWiM 135 Letters

Reed writes:

Dear Vincent, Elio, Michael, and Michelle,

I've just recently finished TWiM number 133 and wanted to comment about the use of the term "secondary metabolite" throughout the episode and often in the primary literature. Michael pointed out that a secondary metabolite is a molecule that is produced by an organism as it reaches stationary phase.

This is actually one of several characteristics that are used to define what a secondary metabolite is. Other common features are that secondary metabolites are "small" molecular weight compounds, they are not involved in the normal growth of an organism, and that they are dispensable for growth and fitness of the producing organism.

However, while many of these molecules are non-essential under laboratory conditions, they may be critical for survival under natural conditions. For example, siderophores are critical for scavenging iron under iron-replete conditions. Pyocyanins produced by Pseudomonas aeruginosa are involved in redox homeostasis. Bacillaene produced by Bacillus subtilis is essential for defense against lysis caused by Streptomyces sp. Mg1 and predation by Myxococcus xanthus. Lugdunin highlighted in the episode is another such case.

Additionally, many of these molecules are produced during multiple growth phases and are not exclusively limited to stationary phase. Taken together, these few examples illustrate that secondary metabolites may be far from "secondary" in their physiological importance. It is for these reasons and more that many have taken to calling these wonderful molecules "specialized metabolites"!

Thank you for the podcast!

Anthony writes:

He withered away for 7 years. Doctors didn’t realize his passion was killing him.
According to the paper, when doctors initially tried diagnosing the man’s illness, they overlooked his daily hobby: playing the bagpipes.
Tests conducted on the man’s bagpipes found a slew of fungi and yeast living inside the musical instrument.
Inside the air bag was a mixture of Paecilomyces variotti, Fusarium oxysporum, Rhodotorula mucilaginosa,and Penicillium species. In a petri dish, they formed a psychedelic swirl of green, orange and red mold.
Henrik writes:


thanks for providing so much information!

I have a mast cell activation syndrome and recently was by Prof. Dr De Meirleir in Brussel to look for chronic infections as a possible cause for mast cell dysfunction. He found that I have positive serology for Tularemia, so it seems that I was in contact with the any of the F. organisms.

He did some follow up tests I will only get to know next month.

My question is: Can the organism F.T. establish chronic infections or will the host either always die or kill the pathogen completely?

Thank you very much,


I asked Katy Bosio:

There have been a few reports of chronic infections with Tularemia, but I think those were largely restricted to the early days of antibiotic therapy (see Public Health Reports, 1926, 41:1341) and were symptomatic.  They also started with a known exposure to F. tularensis.

It sounds as though the listener may be asking if F. tularensis can cause sub-clinical disease, i.e. infection without detected signs of illness.  There is not much data on this either, but there have been some reports suggesting that it is possible (Emerging Infectious Diseases, 2010, 16(2); Emerging Infectious Diseases, 2015, 21(12)).  


Catharine (Katy) M. Bosio, PhD
Senior Investigator
Immunity to Pulmonary Pathogens Section
Laboratory of Bacteriology
Rocky Mountain Laboratories
Hamilton, MT


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