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 26 Letters

Peter writes:
Dear Twim team

An interesting paper on artificial selection of yeast giving rise to evolved  clusters. The clusters evolved to be larger, produce multicellular progeny, and even show differentiation of the cells within the cluster—all key characteristics of multicellular organisms. This took  just 2 weeks, or about 100 generations.

A nice time lapse video of clusters dividing:

While this is very interesting I would be wary of reading too much into it.  How do we know that single celled yeasts have not evolved from earlier multicellular forms? This could be an innate -  previously evolved trait that enables the yeast to develop to a multi celled form with relative ease.

Kimberley writes:

Great job with these podcasts. I really enjoyed the ones I’ve heard.

Someone asked if CEUs are available? What can you tell me about that?

Thank you,

Microbiology Section Leader
Morton Hospital

Peter writes:

Arsenic-based life
In late 2010, NASA researcher Felisa Wolfe-Simon and colleagues reportedly uncovered a species of bacteria in Mono Volume Pills Lake that not only survived in unusually high levels of arsenic and low levels of phosphorus, but also appeared to incorporate arsenic into its DNA backbone. However, critics were soon questioning the results, citing poor DNA extraction techniques and a supposedly phosphate-free growth medium which actually did contain phosphate. Science published 8 technical comments about the work in May, though the paper, which has been cited 26 times, has yet to be retracted.

It seems it was a bad year for publish and perish.

Thomas writes:


I am a graduate student at the University of Georgia, working on my MS is plant pathology.

At the moment I am working my way through TWiP, TWiV, and TWiM.

Do you all have any interest in starting a this week in mycology podcast? I realize that fungi and oomycetes are more interesting to plant pathologists than animal pathologists, but I think this is a fascinating and diverse subject.

Keep up the good work!

UGA Department of Plant Pathology

TWiM 25 Letters

Peter writes:

Dear TWiM team I saw this fascinating paper on how the variety of bacteria populating human skin can influence who mosquitoes chose for their blood meal.
Not really sure if it would be best covered in  TWiM or TWiP as falls within the remit for both podcasts.

Composition of Human Skin Microbiota Affects Attractiveness to Malaria Mosquitoes

It appears that mosquitoes tend to avoid people with more diverse microbial communities on their skin as they contain bacteria that produce volatiles that repel mosquitoes.

Presumably once these particular bacteria have been identified then it may be possible to culture them to produce a mosquito repellent, presumably actually growing the culture on your skin would also work as a biological control, though I think it would be rather harder to market given most peoples fear of bacteria.


Jim writes:


I just saw this engrossing documentary about lyme disease with a controversy about the existence of a chronic form of lyme disease. The movie might be worth a mention as a listener pick. It's 1 hr 44 mins long and can be seen online at  A web site with resources and trailer also exists as  The movie is several years old.  Do TWIM panel members have any current information about the controversy and is progress towards resolution of what is affecting folks with chronic conditions they attribute to lyme being made?  Unfortunately, as noted at the end of the movie, several key researchers have died, including one who had detected Lyme borreliosis in brain tissue samples from deceased Alzheimer patients. I would have liked to have them join the TWIM panel and discuss current activities.

Smithfield, VA

Varun writes:

Hello everyone,

First of all, let me congratulate the microbiology crew for bringing up such a fantastic podcast that makes microbiology so much fun. Since Dr. Moselio is very interested in mitochondrion i thought he probably would know the answer for my question. Its known that only mom's DNA is being passed to their progeny what is the best hgh on the market. Its also known that as you age there is continuous accumulating damage to mitochondrion thanks to the oxygen species. Now my point is why doesn't the mitochondrion which is from mom derived after a few rounds of replication accumulate damage and pass to the child. That doesn't happen (else we already would have high damage in mitochondrion). I hope my question isn't absurd.

I also would really love to hear an episode or 2 entirely dedicated to what we know of HIV on TWiV (Just like the malaria sequence episodes in TWiP). IF you do please focus on HIV genome controls by TAT.

On episode TWiM#22 there was a great snapshot of microbiology in clinic. I just am interested to know if Dr. Alfred have experiences regarding Burkholderia cases in infants. We just happened to see some in premature infants. If yes please light the area.

Am sorry for too many questions and comments. Once again thank you for the great great educast.

Al Sachetti answers:

To be honest I never heard of Burkholderia so if I've seen a case of it I never made the diagnosis.

I looked it up and it is more an infection of the immune compromised, especially those with cystic fibrosis.  A case in an infant would be particularly unusual from what I can tell.  Seems more of a plant pathogen that also infects livestock and is more of an opportunistic human pathogen.  Just more proof, it's the microbes that rule the planet.

On another note, I ran into a pediatric ER doc from Chicago last week who told me they are seeing one of the worst Respiratory Syncytial Virus seasons ever.  This has been our experience with more cases in the last few months than we have seen in the last 3 years combined. This is in the face of no Influenza infections at all this year.

Might be fun to do a Bench Top to Bedside show with an RSV Virologist and a physician on this one.

Have a great New Year.



TWiM 24 Letters

Jayne writes:

Thanks so much for your podcasts. I find I am a person who learns best audibly and have just jumped into the science, history, medical and EMS blogs, I Listen to a podcast called SMART EM by a pair of ED docs, and they covered the issue of UTI in Peds. They do journal and study reviews and the found that there isn't any basis for the idea that untreated UTI causing kidney damage for Peds. I know, I know, but they took the time to ferret out all the info. Anyway, I am enjoying your podcasts. I don't think going back to school is something I can do, but about once a week I go to a class on virology, parasitology and microbiology. The tuition is great. No student loans. No sleeping in class.


Al Sacchetti answered: Jayne is correct and not correct depending on who you read. This is one of those topics that will continue to be debated as it is mostly "soft" science.

It is all based on retrospective case studies so you really can't design what would be considered a good scientific study to prove it. Such a study would involve not treating a cohort of children with urinary tract infections and following them and a second subset of treated children to determine if one group develops more hypertension than the other. Not an ethical study to perform.

The other confounder is that there are multiple other causes of hypertension that may overwhelm the cases caused by infant UTI's.

For me the take home message will not become clear for another two decades. That is how long it will take for this generation of treated children to grow old enough to really look at the epidemiology of their hypertension. (As an aside, it is one of those issues that really will not change our practices since we will always treat a UTI in a child.)

On a different note. What would you think Kamagra Online about doing a TWIV on Hepatitis C with a Hepatitis C Virologist, a Transplant Surgeon, a Hepatologist and possibly a hepatitis C patient? From the Bench to the Bedside type of show.

Take care and continue the great work you do with the all the TW's


Jeff writes:

Hi Guys - I was wondering if you had seen the following article in about the lack of acorns being produced in the Northeast this year. In it they mention that the lack of acorns in the past is associated with crashes in the mouse population, then, the author says: "And because the now-overgrown field mouse population will crash, legions of ticks — some infected with Lyme disease — will be aggressively pursuing new hosts, like humans."

Currently here in Atlanta our oak trees are producing massive quantities of acorns. Every few years oaks will begin producing lots and lots of acorns in a season - a phenomenan thought to saturate their predators and try to increase the odds that ssome of their seedlings will germinate and take root. Is there any way that you could do a show (or part of) on some aspect of this Oak-mouse-tick-Borrelia story? It has the parasites (ecto - tick, endo-Borrelia) angle and it has this beautiful tie in to local ecology. I know it isn't typically what you do on the show, but if you can do some aspect of it that would be great. I am going to use this story in my non-science major introductory biology course next semester for some active learning in the classroom, and being able have my students listen to another TWIP/M/V podcast as preparation for those classroom sessions would be too perfect. Does Dr Gwadz have an expertise on the ecology of lyme disease maybe?

Thank you for the great shows, keep up the great work!


Georgia Perimeter College

Here is the link:

Here is an article in American Scientist which passes for a pretty good review on the subject:

TWiM 23 Letters

Joe writes:

Hello Vincent and Elio

Your recent discussion of mitochondrial interconnections reminded me of a
paper by Dubey and Ben-Yehuda I saw earlier this year describing
intercellular communication utilizing tiny nanotubes that are EM
visualizable and that can transfer DNA, RNA and protein from bacterium to
bacterium.  These structures are able to connect distinct bacterial species
and can confer transient antimicrobial resistance as well as other
phenotypes from one species to another.  I was completely blown away by this
paper and it forced me to think about all of the things that we still don't
really understand about the bacterial world.  The paper is worth looking at
if only for the beautiful microscopy work and elegant experimental details.
I wonder if you'd care to comment on whether this type of mechanism could
explain the origins of the mitochondrial interconnections that you were
discussing on TWIM 21?

I really enjoy the program as it lets me keep up on interesting developments
in areas Ativan Dosage of microbiology outside of my own field.  All the best,

Joe McPhee
Joseph McPhee Ph.D.
Michael G. DeGroote Postdoctoral Fellow
Coombes Laboratory
McMaster University

Don writes:

All hail the microbiologists extrordinarie. I look forward to your discussion of the paper on the use of copper to discourage bacterial growth, as you discussed in an early twim.  I was able to convince myself using a copper plated car battery and CuSo4. ie "root killer" and chicken broth for a medium and clarity as an end point. I have since switched to brass, as  it  is more durable, and already "out there" in the market, avoiding the medical vendor or defense contractor  monetary gouge, but the results have not been quite so clear cut. Could you speculate or theorize why this might be so, for an alloy of copper and zinc, vs Cu alone? I delight in your podcasts, and have filled out your questionnaire/survey. Best to you all and please keep going.


TWiM 22 Letters

Jim writes:

I'm greatly concerned about the harmful effects of nanotechnology. I'm old, but have grand kids, who already have to live with all kinds of junk in the environment. I guess it's a topic that fits in the virology category, too, since are not nanotech-sized particles in the viroid category? The scope of nanotechnology is so great that it looks like a wave of change, just like plastics, so perhaps it has to become an obvious and terrible hazard, like DDT or an epidemic before better controls will be considered. Just thought I'd ask what your take is on the topic.

I ran across a nice 3-part series from Marcy of 2010, if you want to use it as Buy Levitra a springboard, or reference for listeners, although plenty of other discussion is easily found on the web.

Part 1:

Part 2:

Part 3:

Smithfield, VA

Richard writes:

Hi Vincent and hosts,

I have a theory, as to why mitochondria would be involved in programmed cell death. It makes sense that, if they are descended from parasitic bacteria, that mitochondria would have had the ability to kill cells. They may well have needed this in order to spread, from cell to cell.

It makes sense that evolution would adopt something already present, in order to kill cells, rather than inventing something new.

I have no proof, but it does seem reasonable.

Thanks as always, for your interesting group of podcasts.



TWiM 21 Letters

Casey writes:

Dear TWiM'ers,

Thank you for taking the time to produce these podcasts free of charge.  I hope this style of science podcasting continues to inspire other scientists into creating similar podcasts.

On TWiM #17, you discussed the discovery that mealybugs have symbionts within symbionts, which you guys related to the mitochondria.  Until this year, I was consistently taught that mitochondria are individual sausage-shaped organelles.  Due to their size, shape, and molecular data, they appeared to be a bacterium that was phagocytized.  However, I have now come to learn that mitochondria are truly a reticulum similar to the endoplasmic reticulum.  Interestingly, this information was known as early as 1980 when Ezzatollah Keyhani (from Tehran, Iran) published a paper (Observations on the mitochondrial reticulum in the yeast Candida utilis as revealed by freeze-fracture electron microscopy, Journal of Cell Science, 46, 289-297) describing it as a branched reticulum.  The shape commonly used in textbooks is really just cross sections through the reticulum.

My question is: how did these phagocytized bacteria acquire the reticulum?  Were these started as pili that have since evolved into a reticulum?  In addition, why do textbook authors still present the sausage-shaped mitochondria in textbook diagrams as opposed to the reticulum?  Why has not there been a greater push in academia to present the mitochondria as a reticulum?

This whole idea made complete sense when I viewed the mitochondria as small sausage shaped alpha proteobacteria.  I performed a quick literature search but was not able to find any literature examining this question.

Thank you and keep up the excellent work,

1st year PhD student

Cindy writes:
Good Morning,

I absolutely love listening to you guys. I have learned so many things from listening to TWiV, I am sure I will have be a step ahead when I take my advanced biology classes. One question though, Once a certain strain of bacteria becomes resistant to antibiotics, how much do these antibiotics need to be modified to combat an illness caused by this bacteria that has grown resistant? I have done Cialis Online research on this question, but so far I have not found an answer. I hope you guys can help me out with informing me about this process.

Thanks in advance,

jesper writes:

Dear Vincent,

the other day I was in a discussion about what can get cancer, something that ultimately boiled down to what cancer really is. Our reasoning went along the lines of establishing that there are organisms containing any number of cells, ranging from one and up. If I remember correctly, C. Elegans has 957 cells. Presumably there is some organism with 956, 955 and so on.

It seems it doesn't make any sense to talk about a one celled organism developing cancer - though I am interested to have that confirmed! The nematode just mentioned has cell specialization, so it could presumably develop some form of cancer. What is the lower limit of cells an organism must have to succumb to the decease or should the question really be posed in a completely different way?

Also, some organisms of very few cells occasionally gang up and form a super-organism. This includes some slime moulds and the pre-larvae state of jelly fish. Can such "temporary" organisms develop cancer?

The question is grander than just parasites, and I have a feeling that viruses, living or not, have no propensity to develop cancer. Hence my addressing the question to TWIM.

While I have your attention, allow me to once again thank you and everyone in each of the podcast teams for your effort in sharing your knowledge and doing it in such an enjoyable tone and fashion.

All the best,

Software architect

Stan Maloy writes:

I was visiting the University of New Mexico last week and ran into a scientist who said that he LOVES TWIM. His only complaint was that he commutes a long distance on his bike and sometimes gets so caught up in the discussion that he has nearly avoided an accident. Not faint praise from a scientist who is known for being extremely critical.


TWiM 20 Letters

Atila writes:

Dear TWiMers,

The episode 7, about toxins and antitoxins made me think about the relationship between the bacteria and its plasmids, so I would like to share some speculations I made, without reading more about it (as my graduate project with HIV does not let me read about much else). What I would do if I were the plasmid, or what evolution could do to it:

If I were a plasmid coding for a toxin and an anti-toxin, I would make my toxin small and soluble, so it could diffuse away from the bacterial cell. At the same time, I would code for a large and hydrophobic anti-toxin that would get stuck inside of the cell. So, when a bacteria acquired me, I would make it retain me to live, and at the same time kill all neighbors that didn't have the same idea. They have to acquire me as well or they die. This could explain why TB has so many addiction modules, if it loses some, it may die from the toxin secreted by a neighbor.

Now that all the population has a copy of me inside them, and no other bacteria can grow around them, I can make an anti-toxin that responds to a quorum sensing molecule such as a piece of G6PDH. So, I not only guarantee that only my bacteria survives, I also control  that it grows in a controlled manner. Do you think this may be the case in nature?

Congratulations for the great podcast. I have been listening to fantastic discussions about microbiology coming from you and your guests, it is an unique opportunity for someone at Brazil (and other countries, as I imagine) to listen to these scientific conversations. Keep up the nice work.


Alexey writes:

Big thanks for the show, Vincent and co.

I'm 23-year old economist from snowy Russia. About a year ago I got interested in synthetic biology and since than have been learning a lot about genomics, microbiology, biochemistry etc (not without help of your podcasts, which I listen on my way to and from work). But I'm still mostly impressed by the prospects of using biology to create Cialis lifeforms, which can be used to efficiently produce or recycle needed chemical compounds.

Based on stated above i have 2 episode requests/propositions 1. Since I'm 23, I would love to study Biology more in-depth. It would be very helpful (I believe not only for me) to do the survey of existing microbiology related study possibilities and interesting programs in US, Canada or whatever you got detailed information about 2. Since Vincent is virologist, TWiM tends to be disease/infections focused (as TWiP and TWiV). I would really appreciate to hear an episode about non-medical Microbiology application, s.t. Venter's synthetic life creation or current state of affairs in using bacteria to create fuel - in other words something synthetic biology or bioengineering related.

One more time huge thanks for the podcast. It helps people having nothing in common with microbiology except interest not to completely be out of touch.

With respect

Artur writes:

Hi Vincent and Friends,
Great show, always interesting, fantastic speakers, keep up the great work!

I was listening to the #19 podcast, and Michael Schmidt mentioned briefly about the debunking of CC5 mutation and susceptibility to HIV infection in early literature (28 min mark).  I've heard of the CCR5 gene and that having a mutation in it makes a person "resistant to HIV infection", but I"m not sure if that's what Michael was referring to.  I've tried to find more info on what Michael briefly mentioned but searching for CC5 and HIV hasn't resulted in much useful information or answers.  Would you be able to discuss this topic and go more into what was meant by the debunking of the CC5 mutation.


Peter writes:

Dear Doctors I would like your thoughts on this.
My local doctors surgery has automatic doors so you don't have to touch the door handles, however if you have an appointment booked then you register your arrival by using a touch screen monitor. To me it does not seem to be a particularly good idea get loads of people with ill health to touch the same object. There is no antiseptic hand gel to clean your hands after using the touch screen.

Am I right to be concerned.

TWiM 2 Letters

Barbara Hyde writes:

In the discussion of copper, it should be noted that copper has long been added to marine bottom paints as an anti-fouling agent. Now however there is concern about deleterious environmental effects from its leaching out into the waters.

Barbara Hyde, MBA, CAE
Director, Communications
American Society for Microbiology

Kevin writes:


First of all, thank you so much for providing myself and other microbiologists with this excellent podcast. Your very first episode was extremely fascinating to me, and I will be avidly waiting for all of the future episodes. I hope you and your friends can maintain this caliber for your podcast.

I am an analyst in the microbiology laboratory at a modest-sized pharmaceutical manufacturing company. For those of you that are familiar with pharmaceutical microbiology at a sterile manufacturing site, you would understand why the discussion of the laboratory studies on copper as an actual self-sanitizing material would be interesting. For the most part you talked about possible applications in hospitals, but I would love to hear Michael Schmidt's (and others') opinion on possible manufacturing design changes if the FDA were to ever support them. Currently, Laminar Flow Hoods, Isolators, and most equipment in a sterile facility seems to be made out of 316 stainless steel. You already mentioned that stainless steel can easily harbor bacteria on its surface, but would using copper as an alternative really be that much more effective? Stainless steel can be polished smooth enough to ensure no bacteria hide in cracks or irregularities in the surface when sanitizing agents
are used. Speaking of sanitizing agents, could you even hope to sanitize a copper material with a strong oxidizer like bleach or hydrogen peroxide? Even an autoclave would be brutal on copper utensils such as forceps or hemostats. You would almost be making disposable metal materials. I would love to see what the minimum concentration of copper you would need in an alloy in order to keep a 10^3 or possibly even 10^6 reduction in microorganisms! Also, I'd be very interested in seeing how a spore-forming organism reacts to contact with copper. Is the spore-formation process quick enough to save a Bacillus species organism from certain death? These are the kinds of questions that popped into my mind immediately, and I'd love to hear your take(s) on them.

On an unrelated note:

I'm a 25 year old analyst at this company with slightly over 4 years of industry experience. I would be ecstatic if you could take some time in an episode to describe the differences between industry and academic microbiology, focusing on some of the progression (or hierarchy) in those different fields. In my undergrad my classes were entirely pre-Med focused, and it was only by chance that I ended up in the industry. Now knowing what I do about pharmaceutical manufacturing, I wish that I had known more so I could have prepared a more efficient method of getting further in this field. An MBA would make becoming a manager/supervisor so much easier, and a PhD would make a Senior Scientist level more tangible to me. As it stands now I have no idea how to get further ahead, but a 5 year break from college keeps me reluctant to go back to school and start all over again.

Thank you once again for all you do, and best of luck in your research and with this podcast!



David writes:

Hi, I'm a new student of microbiolgy at UBC, working in the Redfield lab. I found your podcast very informative and am looking forward to future episodes. If you are looking for interesting people for I'd like to suggest my supervisor Rosie. Among other things, she has a lot of interesting things to say about the recent arsenic bacteria issue.

Please say hello to Prof. Despommier for me, I've never met him but a few years back we talked about an unfruitful venture to get vertical farming going in Vancouver.


[Rosie Redfield blogs at]

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