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TWiM 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.
long time listener, first time writer. I was just wondering, am I missing something really crucial? I've been reading in the news about Europe's "E.coli virus" everywhere. I have to assume that people are just mis-speaking and they mean illness not virus, but maybe there is a virus of E.coli that is released from the bacteria and are causing some sort of double whammy illness in folks.
Do you happen to know any more about this than I do?
Those of us who teach (undergraduate) diagnostic microbiology are sometimes caught in a dilemma.
On one hand, we need to teach students to process cultures (urines, throats, sputums, blood, stool, etc) and identify organisms that are commonly associated with those specimens..and we all know there are some potential pathogens in the mix.
On the other, we don't want to any kind of exposure incidences.
What recommendations can you guys make about how to handle this situation. We want to keep it "real." We feel the student will work with the organisms on an internship and then once they graduate so we want to make sure they are well prepared. We all wear PPE (gowns, gloves), practice good hand hygiene, and have a Class IIA safety cabinet. I haven't had (knock, knock, knock) any incidences, but I still worry.
I wanted to ask about a comment made by Cliff regarding Salmonella and potato salads. Working from memory, which I apologize if I am wrong, he talked about performing a fun experiment with Salmonella and potato salad. From my understanding, food poisoning from potato salad is not Salmonella sp. at all. Instead, food poisoning from potato salad is typically Staphylococcus aureus exotoxin B. So saying that Salmonella is not typically found in potato salad is true, but it can be misleading because you can still get food poisoning from potato salad with S. aureus. I guess that is not really a question, but truly more of a comment.
I first found TWiP, which led me to TWiV which led me here (Hey Vincent- get on Dickson for more TWiP episodes!). I love all three shows. I work as a research technician at a medical/veterinary entomology lab, and spend several hours of my day counting and identifying mosquitoes caught in traps in rice paddies (when I'm not sitting in a makeshift african hut...) Your podcasts have saved my sanity on multiple occasions! While I work closely with vectors of many of the parasites/pathogens you discuss, it is great to learn about the mechanisms of infection and disease, a subject which I feel I am slightly lacking in.
I just finished reading a couple books about the history and discovery of prions, and while I am not sure they can be classified as microbes, I would love to hear a show on the subject. I've become slightly obsessed! Keep up the great podcasting - I have several thousand more mosquitoes to go!
Look forward to all the TWi* discussions. Last months TWiM on Salmonella, with its reference to Typhoid Fever, reminded me of Bertolucci's twenty year old film masterpiece, The Sheltering Sky in which Port played by John Malkovich contracts Typhoid.
The story written by Paul Bowles, is interesting by itself in that Bowles lives in Tangiers - - where the story plays out - - and for his friendship with William Burroughs. Debra Winger is magnificent as Kit, Malkovich's wife. At the end of the film the viewer struggles with moral issues and whether or not Kit lost her sanity. Reading the book doesn't help.
The photography and the acting are superb. The progression of the Typhoid Fever in Port is accurately portrayed. The source of Port's infection is only hinted at. As one of the World's great films, the film was grossly underrated by film reviewers. Nevertheless, most people with a scientific background will appreciate the film and likely give it the highest ratings.
Hello Team TWiM,
I’ve followed with interest your coverage of Michael’s research into use of copper to fight hospital infection. Of all the interesting papers covered in 2013, I think the one most actionable is episode 55, The Copper Room. His research, described in that and prior shows, addresses an under-reported aspect of our health care system. Hospital acquired infections are a serious matter of which I am especially mindful as I prepare for surgery later this month. Kudos to Professor Michael Schmidt for proving how a relatively simple change of hospital materials can have a huge impact on improving patient health and outcomes.
Let me share some news, and ask follow-up questions.
Monday, 1/6/14, at the Consumer Electronics Show, Corning Inc introduced a new line of “Gorilla Glass” that it claims is the "World’s First Antimicrobial Cover Glass”. Links with information:
— press release: http://www.corning.com/CMS/Overview.aspx?id=60899
— video releases: http://www.youtube.com/watch?v=egU8GLD7MG8&feature=youtu.be
Corning is positioning the product for touch-based mobile devices to combat bacteriological growth and spread of disease. We have all have seen phones whose surfaces are, in plain speech, gross, disgusting and covered with layers of schmutz. TWiM listeners would call such objects “fomites” to use a polite, abstracted, and neutral term.
Here come my questions ….
1. Corning highlights the use of “ionic silver” as the antimicrobial agent in its new glass. Silver, Ag, is in the same column and one row below copper, Cu, in the Periodic Table. Below silver is gold, Au. Do I recall my chemistry correctly in that each has the same number of valence electrons? If this is true, can Michael or other hosts compare-and-contrast how Cu/Ag/Au vary in effectivity killing bacteria? Besides economics, is any of those metals a preferred choice for bacterial killing agent? Why, or why not? Is the preference related to their increasing conductiveness as you descend rows in the Periodic Table?
This question is truly cutting edge… I call your attention to
2. Would you describe in more detail the mechanism by which copper’s valence electrons kills bacteria?
3. What impact does copper have on neutralizing viruses and their ability to spread? I use “neutralizing” because you can’t kill a non-living virus. Do you agree with this phrasing?
Wishing all of you the best in 2014.
PS - the weather. Here in the San Francisco Bay Area the weather these past few days was mostly sunny, with highs in the mid-60’s and lows in the mid-40’s. This east coast refugee empathizes with easterners like TWiM’s Michiganders, Carolinians, Jerseyites, or his brother out on Long Island who have been experiencing extreme cold with daily highs in the low-teens. Only Elio’s San Diego has better weather as I write this.
Greetings Vincent and Team,
On the foremost, thank you for your excellent educast. Your podcasts has helped me generate and understand a lot of ideas which i would have never accomplished had it not been for your podcast. I have just joined, Dept of Neuro-Microbiology, NIMHANS, Bangalore, India as a PhD scholar. Maybe i can consider it a TWiX bump.
The issue of Health Care associated infection has come up, multiple times in your podcast. I have a query in connection with the same.
Hospital environment harbors microbes usually of MDR type. The ones commonly involved in Nosocomial infections are often environment and antibiotic resistant types. There is a very limited scope of competition from harmless and less robust environmental flora. I'm curious if we could (theoretically at least) introduce environmental flora into hospital regularly, which would then reduce hospital acquired infections. Just a wandering thought.
I always have wondered why doesn’t TWiM have Pick of the week. Keep up your excellent work. Never ever stop TWiX.
A yet another TWiX Podcast fan.
Hi Vincent, Elio, Michael and friends,
Firstly, thanks for the show. It regularly blows my mind, and keeps me very engaged during the otherwise cold and rainy walks into work. Keeping up with each episode has very much broadened my mind to microbiological topics that I wouldn’t have come across otherwise, which has in turn enriched my own thinking and work.
In the fascinating TWiM 68 ‘The Fungus Among Us,’ Elio questioned the existence of uninhabited aqueous environments. I know of two naturally occurring habitats on the earth that are most probably functionally sterile (that is, supporting no active growth). These are Discovery Basin in the deep Mediterranean and Don Juan Pond in the McMurdo Dry Valleys, Antarctica. Both of these are extremely concentrated brines, where the main salt is not NaCl, but MgCl2 (in the case of Discovery Basin) and CaCl2 (in Don Juan). Previous studies report DNA sequences from Discovery basin, but the current thought is that these originate from organisms that live above the seawater/brine interface and have simply sunk into it. mRNA has not been successfully recovered, suggesting that there is no active life. Exactly what property of the brine precludes life is not fully understood; it could be either the dramatically low water activity (availability of free water) or the chaotropic, disruptive effect MgCl2 has on biological macromolecules. Check out this paper which discusses support for a chaotropic barrier to life:
Don Juan is a particularly fascinating place, as it never freezes over despite experiencing temperatures down to -40oC. There is much less published biological data on this environment (none with molecular tools), but it is more chaotropic and more concentrated than Discovery brine, and most microbiologists who work with Dry Valleys lakes consider it a sterile environment. These environments are particularly interesting because of the current paradigm (in astrobiology) of liquid water being the holy grail for habitability, and yet even on the earth there are (albeit rare) examples of aqueous environments that may fundamentally preclude life.
On a different note, I thought you might all enjoy this paper exploring some of the novelties of haloarchaeal genome replication:http://www.nature.com/nature/journal/v503/n7477/abs/nature12650.html
I was reminded of it by your discussion of horizontal gene transfer in the archaea. It’s a really nice study and highlights how different and interesting these organisms are when compared to bacteria or eukaryotes. The authors hint toward some profound evolutionary implications in the discussion.
Apologies for the ramblings, and thanks again for all the inspiring discussions.
UK Centre for Astrobiology
School of Physics and Astronomy
The University of Edinburgh
If you can find the backstory to this, it would be an interesting TWiM:
"Passenger with possible TB infection pulled from plane"
A friend of mine just posted this question on tumblr and I thought you all would be the perfect people to address it:
Question of the day: A strain of Flavobacterium (KI72) evolved the capacity to digest nylon, obviously in recent history. Fine and well. How long will it be until one of the cariogenic bacteria species evolves the ability to digest dental resin? After all, we are putting a lot of it on their dinner table.
Original Article: http://recursivemuffin.tumblr.com/post/68921313389
Hi, great podcast. I just wanted to let you all know that stool taking "the shape of the container" isn't a British-ism. I work in the Micro department of a hospital/reference lab and we use this criteria on a daily basis when testing for C Diff. Specimens that are too formed must be rejected for testing, and we've had many discussions about what makes a stool formed or not; the criteria "takes the shape of the container" has turned out to be the best way to decide if we will reject a specimen or not.
Dear Magiis of the Microbes,
In the news here in Sweden there are unfortunately many reports about the spread of C Difficile, and we've had a few deaths as well. Remembering Michaels research about copper surfacing as a means to reduce harmful microbes in hospital settings, it may be of interest to learn that a study has been conducted here to show that using Chlorine and a detailed cleaning protocol reduced infections by 50%. I have not found the publication, but here is (in Swedish) the protocol recommended: http://www.lj.se/infopage.jsf?childId=16504&nodeId=31555. Essentially they swipe all surfaces with Chlorine.
Here is another article about the research in a Swedish medical Journal: http://www.lakartidningen.se/Klinik-och-vetenskap/Vardutveckling/2014/01/Lomskt-och-omfattande-utbrott-av-Clostridium-difficile/
I do not want to make the impression it was unknown that chlorine is effective as an antibacterial. CDC knew this (http://www.cdc.gov/hicpac/disinfection_sterilization/3_2contaminateddevices.html)
Thank you all for a very interesting pod cast!
My name is Jim from Vancouver. I have no formal education in phraseology but am an enthusiastic follower of TWIP, TWIM & TWIV.
Recently I followed a program about yeast infections and the threat to public health they can pose.
My question is would it be possible to isolate the infectious yeast agents and brew a beer that would act as a vaccine against these infections. I understand that the brewing process kills the yeast so there would be no chance of contamination by the dead yeast which would be filtered out in any case. There were plans at one point to add vitamins to beer at one time to improve public health so the idea is not that unusual.
The question is Would this brew provide a heads up to the immune system that would prevent yeast infections from taking hold?
Also, would it be possible to have a TWIF - This Week in Fungus podcast as part of your audio library? There are so many other valid topics that fungus tends to be neglected.
Vince and Dickson, keep up the good work.
I was catching up on the podcasts and in TWIM 64 you discussed antibiotic resistance and connections between animals husbandry use and human disease issues. A recent article in Science “Distinguishable Epidemics of Multidrug-Resistant Salmonella Typhimurium DT104 in Different Hosts” <http://www.sciencemag.org/content/341/6153/1514.full > seems to indicate a lack of transmission from animal to human populations.
A comment was then made that the same potential transmission problems would be true for aquaculture animals, where antibiotic resistance is also an issue. However, we need to keep in mind that there are very few pathogens for fish that are zoonotic (excluding helminthes that go between bears and wild salmon and seals and some fish) and most aquatic pathogens don’t grow at human body temperatures. Even more important, antibiotics almost triple the cost of fish feed and very few antibiotics are allowed and those are only for a few species. Unlike pigs and chickens, where adding antibiotics to the feed improves the growth rate and decreases feed consumption, adding antibiotic to fish feeds provides no growth effect and actually decreases the animals immune system (Rijkers, Teunissen et al. 1980) – not good for husbandry.
I had previously sent to TWIV the following graph showing that decrease in antibiotic use in Norway salmon production as vaccination solved the problems.
Notes: Use of antibiotics (yellow line) and amount of fish produced (blue columns). The numbers on the leftside are the tonnes of fish; the numbers on the right side are the tonnes of antibiotics.
Sources: NMD & Directorate for fisheries, as cited in Ministry of Fisheries (2002).
Activist organizations, including PEW, have had a multi million dollar “de-marketing” campaign against aquaculture in the US and have succeeded in framing the images in the society.
Other aquaculture myths that are sold to the public by environmental activists are caused by the mandated “color added” label on farmed salmon when you include astaxanthin in the diet, despite the fact that the chemical is identical to the astaxanthin that makes wild salmon pink. In addition, most people in the US believe that salmon and other carnivorous fish require fish meal in their diets and are thus depleting the ocean resources. We know enough about fish nutrition to create totally “vegan” diets for carnivorous marine fish which out-perform fish meal based control diets. However, the ingredients used in these vegan diets are also useful in chicken, and pig diets and fish meal is less desirable for these species (it makes chicken taste like fish and egg yokes grey). Economics pushes fish meal into fish diets, not biology and this whole fish meal issue is manufactured by activists for emotional appeal. If all aquaculture went away, the fish meal market would shift back to pigs, cows, chickens, dogs and cat feeds, just it was before aquaculture was a significant business. The international harvesting of fish meal has been constant for about 4 decades while aquaculture has grown by a factor of about 100 times.
One of my interest in listening to TWIV, TWIM, etc. is related to the observation that aquaculture systems are really controlled by the microbiological ecologies. It is like the complexity of the human gut interactions extended to all inside and outside surfaces. This makes discussions on TWIV about phages sticking their heads in mucus very fascinating to me. This effectively put the phage between its bacterial host and the host’s dinner on the animals surface. A very good location for an ambush hunter phage that has almost no mobility (Brownian motion).
I could go on about how aquaculture can solve the food (meat) problem for the coming 3 billion more people on this planet (better meat yield, better food conversion efficiency, when the animals doesn’t have to stand up or keep warm). The world wide growth rate of aquaculture (doubling in about 8 years) will mean that the talents of the TWIV, TWIM scientists will be required to understand how these microbiological ecologies really work and how to control the outcomes. We are seeing research dramatically increasing in every area relevant to trying to understand and control the microbiological ecologies of these complex systems ranging from probiotics, prebiotics, to specific phages for specific bacterial problems (aquatic phage therapy), but the sources of this research are primarily outside the US. As aquaculture takes over the meat production business with its higher conversion efficiencies, the need for scientists who understand these complex systems will increase. Many of the TWIM TWIV followers will have a bright future opportunity outside of conventional academic research.
Sorry about being a bit long winded. Love your programs.
Dallas E. Weaver, Ph.D.
Acellular pertussis vaccine
Thanks for the amazing stuff. Shows how much we have yet to learn.
Cough is an endobronchial symptom. Even whooping cough can be temporarily ameliorated by anaesthetising the epithelium by the inhalation of nebulised lidocaine, the technique used prior to bronchoscopy.
My medical school microbiology is almost from the era of hunter-gatherers with their sticks and stones circa 1968.
If the volume of human knowledge is a sphere, the area of our ignorance (the "known unknowns" - h/t Donald Rumsfeld) is the surface of the sphere. The volume increases by the cube of the radius while the area increases by its square. It leads to the correct perception that our area of ignorance is decreasing relative to the volume of our knowledge. However what lies beyond the surface of the sphere (the "unknown unknowns") is beyond our ken: just as Flatlanders cannot grok what's beyond the dimensions of their world, we cannot grok those unknown unknowns.
"Expelling fomites" - Dr. Michael Schmidt
Fomites are objects (usually solid) in the environment which may (usually passively) harbour microorganisms.
The germ enlarger. Breakthrough in microbiology, which I am surprised is not used today or discussed on TWIM.
How long does it take to become a microbiologist?
I'd never heard of magnetotactic bacteria before and thought perhaps you guys might find this interesting. Not sure if you've mentioned these on TWIM before, if so ignore this email.
Microbiology and Molecular Biology Reviews : MMBR 2013 Sep; 77 (3) : 497-526.
Ecology, diversity, and evolution of magnetotactic bacteria.
Christopher T Lefèvre, Dennis A Bazylinski
I listened to your podcast that discussed the primary literature article "A Burkholderia pseudomallei Toxin Inhibits Helicase Activity of Translation Factor eIF4A" that was published in Science. This article mentions that after the crystal structure for BPSL1549 was determined and they saw that it was a similar structure to CNF1-C, they created a mutated version that was not toxic, which they expected since the same happens in the mutated E. coli version of the protein.
Does this mean that if they find an agent to inhibit the protein that it would likely be able to work on both E. coli and B. pseudomallei toxins since they are similar? And is this a normal technique for treating bacterial infections since by targeting a protein rather than the bacterium it would leave the bacterium alive to make more of the protein toxin?
Hello TWiM team,
Recently I saw an NPR article on a the disease SCID-X1, an X-chromosome linked immunodeficiency disorder where the body has no functioning immune system. I was wondering if I could hear your thoughts on how the microbiota would respond to this. I know prior research has shown that the immune system plays a role in shaping the community composition of the gut flora. How would the microbiota react to a complete absence of an immune system from birth?
Thank you and keep up the great work.
Hello TWiM team,
I’m a senior biology major who is bent on pursuing a career in microbial ecology. Last summer I discovered your podcast and I wish I had started listening earlier. You guys have been so great that you inspired me to start a biology talk show at my university’s radio station, titled ‘Disentangling the Bank’ for the iconic concluding paragraph of Charles Darwin’s On the Origin of Species. It’s a one hour program where two co-hosts and I summarize papers we found interesting that week and talk about the major results and implications. Because of your thorough preparation I’m always telling them to go to the primary source, much to their chagrin. We can’t go as in depth as your show, not only because we lack the knowledge which comes with being in the field for years, but also because this show is aired live to the public. This results in us heavily summarizing each paper. Nevertheless, we have a great time discussing the articles off-air in depth and it has become a sort of running joke that I always have a microbiology paper each week (never taken from your show though). Keep up the great work and thanks for the inspiration.
Just heard TWIM 67 -- excellent of course -- and recalled, like Elio, being in basic training in the 60's when meningitis cases occurred on the base and we had to sleep with all the barracks windows open. I think we were double-bunked but can't recall if we slept head-to-foot, or if adjacent bunks were reversed. It was a cold time of year and open windows didn't improve the experience, but it seems like they were closed after a couple weeks.
Good morning, day, evening (depending on your time of day). Esteemed
Firstly my weather report, for Weston super Mare, uk.
It is currently 3 centigrade (feels like 2C), dew point 4C, humidity
78%, there has been 1mm of rain/sleet, with a 50% chance of further
precipitation, and the wind is 16 km/h from the WNW. It is currently
dark so no visibility, but this is estimated as 2 miles, as it is
cloudy with light rain.
The predicted high for the day (2PM) 9C, with humidity of 68%, and dew
point of 4C, with predicted wind of 21km/h, a 40% chance of
precipitation (rain or sleet), to is expected to be partly sunny, with
good visibility >10 miles predicted.
I hope the weather report meets your increasingly exacting requirements :)
My question is actually fairly simple; Giardia lamblia and a number of
other eukaryotes lack mitochondria. Most of them appear to be
anaerobic, and I can see the point that the mitochondria and electron
transport mechanism might well be selected against.
However, no where can I find if it is clear that mitochondria where
selected against, and lost. Or if these bugs are a branch, that where
started before eukaryotes adopted mitochondria.
I'm not scientist, but simply an interested party. I actually work as
an engineer, on sewage treatment plants. So I do get to see a lot of
bacteria, since they do all the work, treating the sewage. Given
plenty of oxygen, and the correct nutrients, they do a fine job of
this, and then happily settle out, leaving clean enough water that it
can be returned to the environment (or with minimal treatment, and
filtration, to the drinking water supply, as is becoming more
However it is my personal theory, that apoptosis in eukaryotic cells
derives from the incorporation of a once parasitic bacterium. Such a
parasite requiring a method to kill the host cell, in order to
proliferate into the medium, to infect other cells. I hypothesise that
this was co-opted by eukaryotes, in order to allow for apoptosis (or
programmed cell death).
Knowing if apoptosis occurs in eukaryotes that lack mitochondria, and
if they are a pre mitochondria branch, would answer my question.
However I have been unable to find the required information.
I wonder if you can point me in the right direction, and also thought
the subject might lead to an interesting conversation on the podcast.
Many thanks for your ongoing series of podcasts.
I have emailed this to both TWIP, and TWIM. I suspect it is better
suited to TWIM, but my research has been on parasites, since these
seem better studied, so have included TWIP.
Thanks in advance for any insights you may be able to provide, or
simply interesting conversation.
I just saw this article about the rise of drug resistance:
It seemed a bit sensationalized to me, but as far as I could tell was pretty good on the facts, and I thought it might make an interesting listener pick of the week. I'd love to hear what you all think of it.
Reading the article, I wondered what we could do to keep resistance from arising in new antibiotics. For example:
a. Could a drug company refuse to license a new antibiotic for veterinary use or for agricultural use somehow? (Ideally we would just ban mass agricultural use of antibiotics, but who knows whether that will ever happen.)
b. Could someone develop two new antibiotics with different mechanisms of action, but only sell them in a combined form? That would probably slow down development of resistance, sort of like the use of multiple anti-retrovirals in treating HIV patients.
c. Would it be possible to develop a new antibiotic, and then evolve resistant microbes and try to redesign the antibiotic to overcome the resistance? If you went through a couple of these cycles of changing the antibiotic and then evolving resistance to the new antibiotic, is it likely that would yield a final product that was hard to evolve resistance to? Or would the microbes just find a different way to become resistant?
Thanks for your wonderful podcast, and for answering my amateur questions,
Is the effect of silver nanoparticles related to electron transport? What determines which metals will be antimicrobial (copper, silver) and which won't be (iron)?
Dear Dr. Racaniello and friends,
I am a Medical Laboratory Technologist working in clinical microbiology at Mount Sinai Hospital in Toronto, Ontario. I'm an avid listener of TWiV and TWiP and have been hoping you would start a bacteriology-themed podcast for a very long time. The first few episodes of TWiM have been fantastic! As a recent graduate and novice technologist, your podcasts are an excellent way for me build knowledge and to keep current on the infectious disease literature. Now I just have to find a way to get my accrediting body to give me continuing education credits for listening! Have you ever considered getting your podcasts CME accredited for the physicians out there?
Keep up the great work! A big thanks from Canada for TWiM!
Suzanne MD PhD writes:
TWIM is an amazing podcast. I am a Pediatrician from the route of PhD in Molecular Genetics transformed into a MD and now working in the world of primary care pediatrics. Microbiology is 99% of my life. Your podcasts are joyful. Basic observations, research, molecular mechanisms, insights, perspectives, bridging the basic science to the possibilities in medicine and patient care and health care policy. You have filled a nitch. Gut flora hit home. Probiotics were added to infant formulae in Europe long before here in the US. Yogurt and probiotics have been shown to lessen antibiotic associated diarrhea. The ideal age to introduce solids is 6 to 7 months. Why??? Gut flora. Simple and beautiful. I choose to become a Pediatrician, after PhD training and a 5 year postdoc, to bring basic science to children to hopefully improve their lives. Your podcast satisfies my basic science core and provides me with evidence based insights into health care. Thanks!
My ideas for future topics are 1) What is the epidemiology that has so dramatically changed the virulence of Strep and what's up with a vaccine??? 2) UTI's help whats one to do with multi-drug resistance; and 3) If all disease has a microbial relationship, fill me in on Autism and Mental Illness.
From the trenches...
Dr Tom writes:
Long time TWIVVER/TWIPPER, soon to be long time TWIMMER. Love the information. Thought that a podcast on probiotics would be timely. Seems like I (as a pediatrician) am suggesting them more for a multitude of ailments from recurrent abdominal pain to acute gastroenteritis to antibiotic side effect amelioration. Also, it is getting harder to purchase infant formulas without some form of prebiotic or probiotic.
Keep up the great work.
From snowy and cold madison, wi Dr Tom
I am interested to know if it is generally true that pathogenic microbes produce biofilms, also in a polymicrobial infection what are the ecological interactions between the bacteria? Do the biofilms produced by one species protect or inhibit other species?
Could a normally non pathogenic bacteria become harmful if combined in a biofilm with another organism.
I am asking this out of interest, I am a photographer and not involved in any medical research. I do have a long standing interest in science and find your podcasts to be fascinating.
Did you see this paper in PLoS Computational Biology? It's mind-blowing. U. Maryland researchers found evidence for Acinetobacter and Pseudomonas nucleic acid integrated into human chromosomes and mitochondria, possibly causing cancer in some cases.
Bacteria-Human Somatic Cell Lateral Gene Transfer Is Enriched in Cancer Samples
Liquid water without bacteria on earth:
(No mention of exclusion of biological entities.)
Ergot on the forehead: close, but no cigars!
It is used medicinally for treatment of acute migraine attacks (sometimes in combination with caffeine).
Dihydroergotamine (/daɪˌhaɪdroʊ.ɜrˈɡɒtəmiːn/ dy-hy-droh-ur-got-ə-meen; brand names D.H.E. 45 and Migranal) is an ergot alkaloid used to treat migraines.
Spores "blow in".
Bacteria, if spore-formers, may do likewise.
Tinea versicolor/pityriasis versicolor:
Recent research has shown that the majority of Tinea versicolor is caused by the Malassezia globosa fungus, although Malassezia furfur is responsible for a small number of cases.
(Mostly a cosmetic problem.)
Microbiotum & microbiogenome?
Greetings and the usual well earned accolades. I have a few questions about the protective effect of "melanin" in the gut on the reticuloendothelial system. If melanin ?or its precursors are truly insoluable how was the bone marrow protected? Were the mice restrained during radiation to shadow the bone marrow by the gut laden with rooms, or is a melanin precursor responsible for the remarkable effect? To have fed refined melanin instead of the Trader Joe's fungii would answer a lot of questions. It is usually the failure of the bone marrow [reticuloendothelial system] that has killed those people with radiation poisoning, and a protectant would aid such mundane efforts as a manned Mars mission. Thanks again for your gift to science.
Don Kingsley Jr, MD
the letter below posed the question how do prokaryotes perform chemiosmosis with only one membrane.
two membranes are not required for proton gradient-driven ATP synthesis. proton pumps in electron transport chains in the prokaryotic cell membrane concentrate protons inside the cell. this drives membrane-bound ATP synthase, producing ATP inside the cell. in fact, mitochondria are hypothesized to have been derived from endosymbiosis of the ancestors of purple sulfur bacteria.
A perquisite of teaching undergraduates.
I teach high school AP Biology and Microbiology and have a question about ATP sythesis via oxidative phosphorylation in Gram-positive bacteria (and I guess archaens, too). In mitochondria, chloroplasts, and Gram-negative bacteria, it is possible to concentrate cations (hydrogen or sodium) in an enclosed space to drive ATP synthesis through chemiosmosis. I do not, however, understand how this is accomplished in Gram-positive bacteria and have been unable to find a satisfying answer on my own. Some things I found seem to indicate that the cell wall may trap hydrogen ions (I read something about secreted enzymes not gaining function until they made it all the way out of the capsule due to lower than optimal pH levels) or that aerobic respiration only occurs at high efficiency in the deepest layers of biofilms (something about protons concentrating when the attaching surface has a negative charge), which leads me to believe that Gram-positive bacteria are indeed pumping proton
s out into the surrounding extracellular fluid in the hope that they can be used before they diffuse away.
Dear TWiM hosts,
The last few episodes have been great as usual. I wanted to comment on two things.
1. I feel that the term "microbiome" should refer to the set of microbes living in a given environment. It seems to me that there needs to be a term for this idea in any case. As for the set of genes or genomes present in a given sample, am I wrong in thinking that the word "metagenome" is adequate for this? Besides, what exactly do we mean when we add "-ome" to the end of a word? A genome is a set of genes (well, sort of). A proteome is a set of proteins. It seems logical that a microbiome should be a set of microbes. We have the added bonus that a microbiome can also be a biome. I don't know, but perhaps the word was even used in this sense before everyone started overzealously adding "-ome" words to our, um, word-ome.
2. The story from TWiM #67 about melanin-containing fungi living in environments with a lot of ionizing radiation was indeed fascinating, but I am inclined to feel skeptical about the idea that these fungi are actually deriving energy from that radiation. Is there any evidence that the fungi harness the energy of ionizing radiation? I am neither a microbiologist nor a nuclear physicist but my first guess would be that the fungi are merely unusually resistant to radiation - perhaps they are very good at repairing damage to their DNA. This resistance would allow them to thrive where other organisms can't, even while using conventional sources of food. Although I can't say I understand photosynthesis, my impression is that there is a good understanding of how the energy of visible light can be harvested by chemical means. The energy of visible photons must be a good match to the energy of a useful transition between states of a molecule. Of course, ionizing radiation also couples to chemical changes, since it can blow molecules apart, but is there any way to capture the energy when this happens? I haven't heard of anything like this. It is worth finding out, but as Carl Sagan said: "Extraordinary claims require extraordinary evidence."
I am a great fan of TWiV, TWiP, and TWiM. Keep up the great work!