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On Small Things Considered we share our appreciation for the width and depth of microbial activities on this planet. We enjoy writing about unusual and unexpected phenomena in the microbial world. Fortunately, these come our way with great frequency. We rely on contributors with all levels of experience, from undergraduate and graduate students to distinguished microbiologists. Our "Teachers’ Corner" facilitates the use of the blog in the classroom. Some of our blog’s idiosyncratic features include our "Talmudic Questions" (queries that cannot be answered by simply looking them up with Google), "Of Terms in Biology," and our "Fine Reading" posts, each of which features an exceptional research paper. Small Things Considered is sponsored by the American Society for Microbiology.
Elio Schaechter
12 posts
Merry Youle
2 posts
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- December 13, 2011
- 10:02 PM
- 118 views
A Wormful of Bugs
by Moselio Schaechter in Small Things Considered
by Elio
Let’s start out with a little quiz. What examples can you name of endosymbiotic bacteria so tightly packed that they’re nearly wall-to-wall within cells of their host? If you said legume root nodules, you can claim a prize. (Ask someone else for it, as we don’t have any.) You would get bonus points if you also mentioned the bacteria-filled bacteriocytes of certain insects or the celebrated giant tube worms found near the deep sea black smokers. By the way, the root nodule symbiose........ Read more »
Gruber-Vodicka HR, Dirks U, Leisch N, Baranyi C, Stoecker K, Bulgheresi S, Heindl NR, Horn M, Lott C, Loy A.... (2011) Paracatenula, an ancient symbiosis between thiotrophic Alphaproteobacteria and catenulid flatworms. Proceedings of the National Academy of Sciences of the United States of America, 108(29), 12078-83. PMID: 21709249
Leisch N, Dirks U, Gruber-Vodicka HR, Schmid M, Sterrer W, & Ott JA. (2011) Microanatomy of the trophosome region of Paracatenula cf. polyhymnia (Catenulida, Platyhelminthes) and its intracellular symbionts. Zoomorphology, 130(4), 261-271. PMID: 22131640
- November 30, 2011
- 11:41 PM
- 213 views
Is a Good Offense the Best Defense?
by Moselio Schaechter in Small Things Considered
by Merry Youle
Most eukaryotes possess an RNA interference system (RNAi) that they use to regulate gene expression and to defend against viruses and other mobile elements. However, some budding yeasts, such as Saccharomyces cerevisiae, appear to get along just fine without it even though RNAi has benefited other yeasts by silencing transposons in particular. How do these yeasts that lack functional RNAi systems compete with closely related species that do? And how come they don’t have RNAi wh........ Read more »
Drinnenberg IA, Fink GR, & Bartel DP. (2011) Compatibility with killer explains the rise of RNAi-deficient fungi. Science (New York, N.Y.), 333(6049), 1592. PMID: 21921191
- November 30, 2011
- 11:39 PM
- 208 views
Virus Hacks Intercellular Communications Network
by Moselio Schaechter in Small Things Considered
by Merry Youle
What do monocytes, lymphocytes, and neutrophils all have in common? Well, yes, they are all leucocytes and part of our immune system, but what else? They all can be prompted to migrate to the site of infection...... Read more »
Alcami, A., & Lira, S. (2010) Modulation of chemokine activity by viruses. Current Opinion in Immunology, 22(4), 482-487. DOI: 10.1016/j.coi.2010.06.004
- November 30, 2011
- 11:39 PM
- 150 views
A Pestis from the Past
by Moselio Schaechter in Small Things Considered
by S. Marvin Friedman
In recent decades we’ve come to realize that victory goes not to the swift or to the strong, but to the immune. The introduction of agents of deadly diseases into immunologically naïve populations determined momentous events in human history. The conquest of the Americas resulted in good part from the decimation of native people by diseases brought by the Spaniards, such as smallpox and measles. Two seminal books, one by William McNeill and the other by Jared Diamond, c........ Read more »
Bos KI, Schuenemann VJ, Golding GB, Burbano HA, Waglechner N, Coombes BK, McPhee JB, DeWitte SN, Meyer M, Schmedes S.... (2011) A draft genome of Yersinia pestis from victims of the Black Death. Nature, 478(7370), 506-10. PMID: 21993626
- November 30, 2011
- 11:37 PM
- 198 views
The Lyme Disease Spirochete Feasts on Tick Antifreeze
by Moselio Schaechter in Small Things Considered
This article is lightly modified from one published in the blog Spirochetes Unwound by Microbe Fan. With kind permission of the author.
by Microbe Fan
In the northeastern United States the Lyme disease spirochete Borrelia burgdorferi spreads from one white-footed mouse to another by hitching a...... Read more »
Pappas CJ, Iyer R, Petzke MM, Caimano MJ, Radolf JD, & Schwartz I. (2011) Borrelia burgdorferi requires glycerol for maximum fitness during the tick phase of the enzootic cycle. PLoS pathogens, 7(7). PMID: 21750672
- November 30, 2011
- 11:35 PM
- 190 views
Phage Lambda’s Polar Expedition
by Moselio Schaechter in Small Things Considered
by Merry Youle
For a long, long time, phage lambda (λ) has known that its E. coli host was not simply ‘a well-stirred bag of enzymes’ (something we’ve come to appreciate only relatively recently). This is vital information for lambda since it needs to interact with two particular host proteins in order to launch an infection. One is its receptor (LamB) located on the outer membrane (OM), the other is an inner membrane protein, ManY.
ManY works for E. coli as part of the inner membra........ Read more »
Edgar R, Rokney A, Feeney M, Semsey S, Kessel M, Goldberg MB, Adhya S, & Oppenheim AB. (2008) Bacteriophage infection is targeted to cellular poles. Molecular microbiology, 68(5), 1107-16. PMID: 18363799
Gibbs, K., Isaac, D., Xu, J., Hendrix, R., Silhavy, T., & Theriot, J. (2004) Complex spatial distribution and dynamics of an abundant Escherichia coli outer membrane protein, LamB. Molecular Microbiology, 53(6), 1771-1783. DOI: 10.1111/j.1365-2958.2004.04242.x
- November 30, 2011
- 11:34 PM
- 222 views
Bacteria Living Without Phages?
by Moselio Schaechter in Small Things Considered
By Merry Youle
Are there environments where there are abundant bacteria and no phages? Sounds like one of our Talmudic Questions, but this one has a specific answer, and that answer is Yes. That environment was found within a cystic fibrosis (CF) lung.
This story comes from a pair of papers recently published by a group of microbial ecologists reporting their survey of the microbes and DNA viruses present in the lungs of two late-stage CF patients. Previous studies had all relied on sample........ Read more »
Willner D, Haynes MR, Furlan M, Hanson N, Kirby B, Lim YW, Rainey PB, Schmieder R, Youle M, Conrad D.... (2011) Case studies of the spatial heterogeneity of DNA viruses in the cystic fibrosis lung. American journal of respiratory cell and molecular biology. PMID: 21980056
- November 28, 2011
- 12:00 PM
- 149 views
Are You Me or Am I You?
by Moselio Schaechter in Small Things Considered
by Elio
When one cell meets another, it must make decisions. This extends itself to practically every attribute of living things, from avoiding mating with self to the establishment of territorial boundaries. Do we fuse? Will you attack me? Are you a potential mate or are you lunch? And, in the bodies of vertebrates, are you something that my immune system should recognize as foreign? Microbes are not exempted from these quandaries, being that they carry out lively conversations for purposes as........ Read more »
Gibbs KA, Wenren LM, & Greenberg EP. (2011) Identity gene expression in Proteus mirabilis. Journal of bacteriology, 193(13), 3286-92. PMID: 21551301
- November 21, 2011
- 12:00 PM
- 149 views
Ringing a Microbial Dinner Bell
by Moselio Schaechter in Small Things Considered
by Mark Martin
A few weeks ago, I wrote a short Small Things Considered essay describing the diverse roles that odors can play in microbiology. Articles here and there written by others attest to a growing interest in sociomicrobiology. As for myself, I have long suspected that microbes are constantly sending and responding to a wide communication ‘bandwidth’ of rich chemical chatter, and that other organisms can use or eavesdrop on those signals. Such communication is common in the eukaryo........ Read more »
Leroy PD, Sabri A, Heuskin S, Thonart P, Lognay G, Verheggen FJ, Francis F, Brostaux Y, Felton GW, & Haubruge E. (2011) Microorganisms from aphid honeydew attract and enhance the efficacy of natural enemies. Nature communications, 348. PMID: 21673669
- August 22, 2011
- 01:00 PM
- 419 views
Going Next Door Without Getting Your Feet Wet
by Moselio Schaechter in Small Things Considered
by Elio
Intracellular life has its perks. Inside host cells, bacteria are protected from neutrophils, complement, antibodies, some antibiotics, and the other unpleasant things floating around in tissue fluids. In addition, here they have access to ample food. But there is a catch, namely how to infect other cells and other hosts.
Intracellular life has ancient and distinguished origins. When unicellular eukaryotes first arose, not only did they arise because someone (whoever it was) ingested a........ Read more »
French CT, Toesca IJ, Wu TH, Teslaa T, Beaty SM, Wong W, Liu M, Schröder I, Chiou PY, Teitell MA.... (2011) Dissection of the Burkholderia intracellular life cycle using a photothermal nanoblade. Proceedings of the National Academy of Sciences of the United States of America, 108(29), 12095-100. PMID: 21730143
- August 15, 2011
- 01:00 PM
- 353 views
And We Thought We Knew What CRISPRs Do!
by Moselio Schaechter in Small Things Considered
by Merry Youle
Imagine that you have been growing Pseudomonas aeruginosa strain PA14 in your lab for some time, studying biofilm formation among other things. A student in your lab isolates a phage, dubbed DMS3, that mediates generalized transduction between this and other P. aeruginosa strains. Oddly, this strain, when lysogenized by DMS3, no longer forms biofilms or swarms, both group behaviors. Odd indeed. This is what actually happened in the O'Toole lab at Dartmouth, and this occurrence ........ Read more »
Zegans ME, Wagner JC, Cady KC, Murphy DM, Hammond JH, & O'Toole GA. (2009) Interaction between bacteriophage DMS3 and host CRISPR region inhibits group behaviors of Pseudomonas aeruginosa. Journal of bacteriology, 191(1), 210-9. PMID: 18952788
Cady KC, White AS, Hammond JH, Abendroth MD, Karthikeyan RS, Lalitha P, Zegans ME, & O'Toole GA. (2011) Prevalence, conservation and functional analysis of Yersinia and Escherichia CRISPR regions in clinical Pseudomonas aeruginosa isolates. Microbiology (Reading, England), 157(Pt 2), 430-7. PMID: 21081758
- August 8, 2011
- 01:00 PM
- 503 views
Some Like it Cold
by Moselio Schaechter in Small Things Considered
by S. Marvin Friedman
About 70% of Earth’s surface is ocean. In all of them, the temperature at depths of 1000 meters or more is a constant 4 °C, constituting a vast environment populated by a diverse group of psychrophilic (“cold-loving”) microorganisms. Much of terra firma also lies in the realm of the psychrophiles: more than 20% of all soils are permafrost. Scattered about are a variety of other specialized psychrophilic environments, including cryopegs (saltwater pockets within perm........ Read more »
Piette F, D'Amico S, Struvay C, Mazzucchelli G, Renaut J, Tutino ML, Danchin A, Leprince P, & Feller G. (2010) Proteomics of life at low temperatures: trigger factor is the primary chaperone in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125. Molecular microbiology, 76(1), 120-32. PMID: 20199592
- August 1, 2011
- 01:00 PM
- 396 views
The Janus Bug
by Moselio Schaechter in Small Things Considered
If you wonder what I do with myself when I'm not blogging, well I'll tell you. Among other things, I participate in an ASM-sponsored podcast called This Week In Microbiology (TWIM). It’s posted every two weeks and is easily accessible by clicking here or going to the MicrobeWorld home page. Under the leadership of Columbia University’s podcaster extraordinaire Vincent Racaniello, we sit before our computers and schmooze away about a couple of papers that caught our fancy. Recently, one of th........ Read more »
Arnold IC, Dehzad N, Reuter S, Martin H, Becher B, Taube C, & Müller A. (2011) Helicobacter pylori infection prevents allergic asthma in mouse models through the induction of regulatory T cells. The Journal of clinical investigation. PMID: 21737881
- July 25, 2011
- 01:00 PM
- 326 views
Now That's Using Your Head!
by Moselio Schaechter in Small Things Considered
by Merry Youle
Something bizarre can be seen in TEMs of a Caulobacter crescentus phage, φCbK. This was first reported in a paper published back in 1972 (see the image to the right). In most respects, φCbK is your typical ho-hum siphovirus with an elongated head (60 nm diameter, 200 nm long) sporting a 290 nm long non-contractile tail with the usual tail fibers. But even with the limited imaging techniques available in 1972 these researchers could see that this phage has a single long filame........ Read more »
Guerrero-Ferreira RC, Viollier PH, Ely B, Poindexter JS, Georgieva M, Jensen GJ, & Wright ER. (2011) Alternative mechanism for bacteriophage adsorption to the motile bacterium Caulobacter crescentus. Proceedings of the National Academy of Sciences of the United States of America, 108(24), 9963-8. PMID: 21613567
- July 18, 2011
- 01:23 PM
- 365 views
Rafting Through Time
by Moselio Schaechter in Small Things Considered
In the placid old days, cell membranes were assumed to be fairly simple affairs: lipid bilayers with some proteins floating in them like corks. This “fluid mosaic” arrangement took a beating around the 1970’s, when biophysicists suggested that membranes may be composed of microdomains, where certain lipids and proteins become segregated into what became known as lipid rafts. With further work, these turned out to be places where specific lipids such as steroids and sphingolipids concentrat........ Read more »
López D, & Kolter R. (2010) Functional microdomains in bacterial membranes. Genes , 24(17), 1893-902. PMID: 20713508
- July 11, 2011
- 01:00 PM
- 662 views
Viruses that Infect Parasites that Infect Us: The Matryoshka Dolls of Human Pathogens
by Moselio Schaechter in Small Things Considered
by Jamie Schafer
We’re all too familiar with the viruses that can infect us, from the common cold to yellow fever virus to the endogenous retroviruses that make up a chunk of our genome. Many of us are also acquainted with parasites, such as tape worms or Giardia, that like to set up camp in the human body. But the world of parasites and viruses does not end there. Many parasites or endosymbionts can be infected with viruses. A classic example is Paramecium, which can harbor an endosymbiotic ........ Read more »
Ives A, Ronet C, Prevel F, Ruzzante G, Fuertes-Marraco S, Schutz F, Zangger H, Revaz-Breton M, Lye LF, Hickerson SM.... (2011) Leishmania RNA virus controls the severity of mucocutaneous leishmaniasis. Science (New York, N.Y.), 331(6018), 775-8. PMID: 21311023
- July 7, 2011
- 01:00 PM
- 424 views
Taking Bugs Out For a Spin
by Moselio Schaechter in Small Things Considered
by Linh Truong and Shabana Din
Microbes are the most robust of all life forms inhabiting our planet. Their ability to proliferate in extreme temperatures, pH, pressure, and radiation is well documented. They not only withstand but grow at physical extremes, which makes us wonder about the physical bounds for life not...... Read more »
Deguchi S, Shimoshige H, Tsudome M, Mukai SA, Corkery RW, Ito S, & Horikoshi K. (2011) Microbial growth at hyperaccelerations up to 403,627 x g. Proceedings of the National Academy of Sciences of the United States of America, 108(19), 7997-8002. PMID: 21518884
- July 4, 2011
- 01:00 PM
- 446 views
How We Tell The Good Bacteria From The Bad
by Moselio Schaechter in Small Things Considered
by Micah Manary
Recently, Yale’s Richard Flavell led a team of researchers into the most talked about and yet one of the least understood of microbial environments—the human gut. Rather than present the usual metagenomic characterization of the microbial population, he teamed up with Jeff Gordon at Washington University in Saint Louis and others to investigate one of the most important questions in the field: how does the host organism detect and respond to the replacement of its ‘normal........ Read more »
Elinav E, Strowig T, Kau AL, Henao-Mejia J, Thaiss CA, Booth CJ, Peaper DR, Bertin J, Eisenbarth SC, Gordon JI.... (2011) NLRP6 Inflammasome Regulates Colonic Microbial Ecology and Risk for Colitis. Cell, 145(5), 745-57. PMID: 21565393
- June 27, 2011
- 01:00 PM
- 573 views
Some Like It Curved
by Moselio Schaechter in Small Things Considered
by Elio Think about it: understanding what goes on inside any cell is hard enough. Add to that the complexities of being rod-shaped, and the mind starts to boggle. People have wondered about this aplenty. For sure, many expeditions have set out to explore the poles of rod-shaped bacilli—how they are created, what molecules prefer to reside at this site...... Read more »
Renner LD, & Weibel DB. (2011) Cardiolipin microdomains localize to negatively curved regions of Escherichia coli membranes. Proceedings of the National Academy of Sciences of the United States of America, 108(15), 6264-9. PMID: 21444798
- May 30, 2011
- 01:00 PM
- 480 views
Hard Biology
by Moselio Schaechter in Small Things Considered
by Elio
For some time, I've had the urge to learn something about diatoms. They are dazzlingly beautiful, relatively easy to manipulate, and have left a fossil record immense in quantity. I never had followed up on this yen, so here’s my chance. A recent paper shed light on the way they make their hard shells.
Diatoms are busy creatures, accounting by their photosynthesis for about 20% of the global primary production of organic material, an amount comparable to that produced by the tropical........ Read more »
Scheffel A, Poulsen N, Shian S, & Kröger N. (2011) Nanopatterned protein microrings from a diatom that direct silica morphogenesis. Proceedings of the National Academy of Sciences of the United States of America, 108(8), 3175-80. PMID: 21300899
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