Various bacteria
tsmith | June 23, 2006I have an admission. I am tattooed. Twice. A small thing, but it's pretty incredible at the visceral reactions I sometime receive when people find out. (They're not in oft-seen areas under normal attire, but neither are they anywhere "naughty.") I get head shakes and tongue-clucks from many of my elders; nose crinkles from folks of my own generation who simply think tattoos are unattractive (either on anyone, or on women specifically), or compliments from people who are inked themselves. I understand the range of reactions and hey, to each their own--I'm all for diversity of opinion.…
tsmith | June 20, 2006[From the archives; originally posted November 22, 2005]
Carl Zimmer has a post today about the work of Dr. Bryan Grieg Fry on the evolution of snake venom. If that name sounds familiar to those of you who aren't reptile specialists, you may have run across Dr. Fry's homepage, or you may have seen his research profiled previously on Panda's Thumb here, or you may have read comments by the good doc in this thread. Zimmer, as always, has an excellent overview of Fry et al's new paper in Nature (link ), but he didn't emphasize the one sneak peek I received from Bryan.
This tasty bit of…
tsmith | June 19, 2006[From the archives; originally posted November 28, 2005]
Have you ever wondered how Kevin Bacon and the lights of fireflies related to malaria and power grids? I know it's something that's kept me up many a sleepless night. One word: interconnections.
Many of you have probably heard of the "Six degrees of Kevin Bacon"game. This is based on the work of Stanley Milgram beginning in the 1960s, and brought up again more recently in a 1998 Nature paper, "Collective Dynamics of 'Small-World' Networks," by mathematicians Watts and Strogatz. Milgram conducted a number of studies using his "lost…
tsmith | June 16, 2006Welcome to the June edition of Animalcules! Apologies for the lateness; I only had a few minutes to get online yesterday, and that was mainly devoted to checking email and making sure there were no crises that needed my attention. So, without further ado...
From the Scientific Creative Quarterly comes a humorous entry: Prokaryotes of America Unite. Almost makes me feel bad. (You also may want to check out Scientific Creative Quarterly editor David Ng's new blog here at Scienceblogs: The World's Fair.
Jennifer over at Science Matters has a nice post discussing background information on…
tsmith | June 15, 2006[From the archives; originally posted November 16, 2005]
I know, everyone's so sick of all the new "omics"es. But "metagenomics" is one that I don't see going away anytime soon. At its core, metagenomics is a way of looking at organisms in concert as a complex ecology, rather than as an individual, as genomic analysis has traditionally been done. Rather than isolating 10 different species of bacteria from, say, a gram of soil and analyzing them all separately, a metagenomics strategy would investigate all the organisms in the soil (or in sea water, dental plaque, or even human feces). A huge…
tsmith | June 14, 2006[From the archives; originally posted October 27, 2005]
Pili (singular: pilus) are bacterial organelles--thin tubes of protein that function in attachment and bacterial sex, as well as immune evasion. Traditionally, studies of pili have been carried out in gram-negative bacteria, such as E. coli and Neisseria species; very little was known about pili in gram-positives. A few recent high-profile papers have changed that.
Back in July, an Italian group analyzed the genomic sequences of 2 isolates of Streptococcus agalactiae, or group B streptococcus, in order to identify surface proteins…
tsmith | June 13, 2006 Sometimes it's amazing just how little we know about the microbes around us. For precious few microbes, we know a good deal about virulence factors--genes and proteins that, when present, increase the severity of disease either in animal models or in humans (or both). However, much of this research has been done investigating acute infectious diseases, where one is infected, becomes ill, and gets better in the course of a few weeks to a month. Much less is known about factors that affect long-term (or chronic) infection. A recent study addressed one gap in this research, examining what…
tsmith | June 9, 2006The new issue of Nature Medicine has a number of excellent articles on topics in infectious disease. I'm going to discuss a few of them in more detail next week (or possibly the week after; next week will be a short one for me), but in the meantime, I'll highlight two articles in particular that may interest readers: Here on the midwest mumps outbreak, and this story on phage therapy to treat "superbug" infections. (It just happens to be written by Thomas Häusler, who is the author of the book I reviewed in this post.
tsmith | June 9, 2006Over at Doc Around the Clock, Dr. IBear has a nice post on Lyme disease: what it is, what it's not, and how to deal with ticks (appropriately, not as his mom removed them). He mentions this:
Most of the time people who get Lyme disease don't even know or remember being bitten by a tick. Thus, it stands to reason that if you do remember being bitten by a tick you probably don't have Lyme disease.
I want to elaborate on this just a bit, below.
A reason many people don't realize they've been bitten is because when the tick bites the human to transmit the Borrelia spirochete, it's not always a…
tsmith | June 3, 2006More interesting stuff I didn't get to...
First, outbreak news that I've not had a chance to write about. A huge cholera outbreak is ongoing in Angola; meanwhile, a small measles outbreak has been reported in Boston.
Invasive bullfrogs may be spreading around the deadly chytrid fungus that has been implicated in mass amphibian deaths around the world.
The FDA has approved a new shingles vaccine for adults who had chickenpox.
New studies show that the time to get kids interested in science is when they're young.
And something I keep meaning to mention...BlogHer. Not familiar? Read all…
tsmith | June 2, 2006John Hawks highlights a new article in today's Science, Metagenomic Analysis of the Human Distal Gut Microbiome. This goes nicely with the posts here recently on the topic of how our microbes affect our health and weight (part I; part II). A bit of discussion of the new article below...
First, I want to briefly mention what "metagenomics" means. There's a nice overview of it here on wikipedia. Basically, instead of sequencing and assembling a genome one at a time, you take a raw sample (such as dental plaque, sea water, soil, or fecal material, in this case), isolate the DNA, sequence it…
tsmith | May 30, 2006Busy today, so sequels are on tap. There's an interesting story from Nature news that's a nice follow-up to this recent post on how microbes can influence weight. More after the jump.
Scientists have identified a key microbe in our guts that helps us glean more calories from food. The discovery backs the idea that the type of microbes in our gut help to determine how much weight we gain, and that seeding the intestine with particular bugs could help fight obesity.
Samuel Buck of Washington University in St Louis, Missouri, and his colleagues focused on one microbe called…
tsmith | May 26, 2006Species of the bacterium Clostridium have long been a scourge of humans. They are gram-positive, spore-forming bacteria that can be found in the soil around all of us. The spores then germinate when exposed to anaerobic conditions.
Clostridium botulinum is the cause of botulism, a serious and potentially fatal paralytic illness often caused by ingestion of contaminated foods. More recently, the bacterium has been used as the source of that anti-wrinkle miracle, BoTox: botulinum toxin type A, allowing all of Hollywood to smile without a wrinkly forehead (ah, the wonders of nature!).…
tsmith | May 22, 2006 Razib mentioned here an article in the Boston Globe "which profiles researchers who suggest that variation in gut flora (the mix of bacteria) might be the cause of differences in body weight." The comments are somewhat skeptical, and I started to write a comment on the topic but it became a bit unweildly--so I've added it below instead.
As I've discussed previously, figuring out the relative contributions of environment versus genetics in obesity isn't an easy feat. As with so many human diseases/conditions, the "cause" is certainly multi-factorial. It's pretty clear that the genetics…
tsmith | May 21, 2006Or Saturday roundup, belated. Some interesting stories I didn't have time to cover:
The HPV vaccine, aimed at reducing the incidence of cervical cancer, has moved a step closer to approval.
The Institute of Medicine calls for more research into and oversight of vitamin supplements.
Continuing debate over "The Hobbit."
New research might eventually bring breathalyzers to your doctor's office. Not necessarily for alcohol.
An interesting study of experimental evolution: selecting for heat-tolerant bacteria over 1500 generations.
Yet another use for bacteriophage: diagnosis of…
tsmith | May 19, 2006 So, archaea are apparently the topic of the week. While I wrote here about the pathogenic potential of some species of these organisms, a new essay in Nature and a new review in Science focus more on their evolution (and the evolution of the other two domains of life) than any health application.
In the essay mentioned, Norman Pace discusses the eukaryote/prokaryote dichotomy. Currently the archaea are classified as prokaryotes since they, like bacteria, lack a true nucleus. However, molecular sequence analysis has shown that the archaea and eukaryotes are actually more closely related…
tsmith | May 18, 2006Welcome to the new edition of Animalcules!
First, a few housekeeping notes. If you note the schedule, I've not yet extended it beyond June 1st. I think that, at least for the summer months, Animalcules will be a once-monthly carnival, rather than every other week. If things pick up after that, I'll change it back to the current set-up, but that will be dependent not only on entries but also on additional hosts. So, if you'd like to host in July, August, or September, drop me a line (aetiology AT gmail DOT com) an I'll get you on the schedule.
Okay...on to the entries!
We have a few…
tsmith | May 17, 2006When I was in school, I was taught about the 5 kingdoms of life: Monera (all bacteria), and the eukaryotes: Protista, Fungi, Plantae, and Animalia. Since that time, there's been a bit of a change in the organization. This is largely due to investigation of the Archaea (sometimes still referred to as "archaebacteria"). It was recognized that these organisms were so unlike bacteria (and of course, unlike the eukaryotes) that they deserved their own grouping. Therefore, the most common strategy currently employs 3 domains of cellular life at a level above the kingdom: Bacteria,…
tsmith | May 16, 2006 On a recent episode of the drama House, the medical team finds that a patient improves from his illness when he's infected with a particular species of bacteria, Legionella pneumophila. Though mysterious at the time because the cause of the patient's illness was unknown, it was later determined that the patient was infected with naegleria, an amoeba. Legionella is an intracellular bacterium that just happens to naturally live in amoeba. Therefore, when the patient was co-infected with the amoeba and Legionella, the Legionella killed off the amoeba--using one microbe to attack another.…
tsmith | April 29, 2006More topics I'd have covered this week, given endless time and energy:
An update on the Chikungunya outbreak I discussed here (and see this comment on the outbreak from a medical entomologist in the region dealing with it first-hand).
Orac on viruses as cancer treatment, inspired by a recent episode of House (more episode reviews by Scott at Polite Dissent can be found here).
An update on mumps activity from the Iowa Department of Health. I haven't written about this in a few days because there's not much more to tell. Cases are still increasing, and they're recommended that students…