General biology
tsmith | October 31, 2007Salmonella species are frequent human pathogens. An incredibly diverse genus, different types of Salmonella infect an enormous variety of species, from mammals to fish to invertebrates. They are typically acquired via ingestion of contaminated food or water, and the bacteria then seed the intestine and replicate there. These gram-negative organisms are the cause of typhoid fever (Salmonella enterica serovar typhi) and can also cause acute gastroenteritis (multiple types, including Salmonella enterica serovars enteritidis and typhimurium).
Of these types, S. typhi is the most deadly, and…
tsmith | October 23, 2007It's only taken 30 years, but information about Ebola in nature is finally starting to snowball. First, after almost 15 years of disappearing from the human population, Ebola returned with a vengeance in the mid 1990s, causing illness in 6 separate outbreaks in Gabon, Ivory Coast, Democratic Republic of Congo (DRC), and South Africa (imported case) between 1994 and 1996. As doctors and scientists rushed in to contain the outbreaks, they were also able to collect viral samples, and trap animals and insects in the area, searching for a reservoir for the virus. In this decade, there have been…
tsmith | September 17, 2007 Regular readers may have seen me mention on occasion my father's rather large family. My dad is the youngest of a family of 13 children--12 of whom survived to adulthood. Before my dad was born, he lost a brother to complications from infection with chicken pox; he had a severe infection and developed a fatal secondary pneumonia at just a year old. This was back in the early 1940s, prior to the widespread use of modern antibiotics and certainly long before vaccination for chicken pox. Still, despite the availability of effective chicken pox vaccines today, people still knowingly…
tsmith | September 12, 2007I mentioned that it's microbiology week at fellow Scienceblog Deep Sea News. Today's post over there is on "bioprospecting" in the sea--looking for naturally-produced chemicals that we can harness for employment as drugs or other uses. For example:
Over the last 20 years at Harbor Branch Oceanographic Institution we have developed a culture collection containing 17,000 bacteria and fungi from deep-water marine invertebrates and sediments. We have shown that the collection contains many unusual microbes which are not known from the terrestrial environment and are fermenting the isolates to…
tsmith | September 10, 2007We owe a lot to the sea for studies of microbiology, so why not? Head over to Deep Sea News this week and check out their microbiology posts.
tsmith | September 6, 2007While E. coli typically makes the news as a food-borne pathogen, that's only one facet of the bacterium. It can be deadly, sure, but it also helps us digest our food; it produces vitamin K for us; benign strains can even protect us from invading pathogens. It's one of the most-studied bacterial species and a "workhorse" for research in microbiology and molecular biology. We use it as a marker of fecal contamination in water, and it can even be used to produce insulin for diabetes patients. So it may come as no surprise that it may one day be a cavity fighter as well:
Imagine being able…
tsmith | August 31, 2007 As I mentioned in the introductory post, we know incredibly little about the very basics of Marburg virus ecology and epidemiology. The sporadic nature of outbreaks of illness, their occurrence in remote areas of Africa lacking established medical research capabilities, and often in countries experiencing governmental strife and instability, compound the difficulty of determining the ecology of this particular virus. Often, the primary case (the first person in an outbreak known to be infected, and who likely acquired the virus from its wild reservoir) died before questions could be…
tsmith | July 17, 2007By now, regular readers will probably be familiar with The Clergy Letter Project spearheaded by Michael Zimmerman. Formulated in part to respond to the framing of the evolution controversy as a battle between science and religion, the letter now boasts more than 10,700 signatures from clergy, and have sponsored Evolution Sunday events for the past 2 years.
Well, Zimmerman has a new project now:
Our latest initiative is to create a list of scientists around the world who are willing to answer scientific questions posed by clergy who are supportive of modern science in general and evolution…
tsmith | June 29, 2007Last year, I mentioned some ongoing research suggesting a link between exposure to light and the development of breast cancer. As I mentioned then:
While we know a good deal about factors that can contribute to breast cancer risk--including genetics (such as mutations in the BRCA1 and BRCA2 genes) and lifestyle choices (late or no childbearing, high fat diet, lack of exercise), many environmental risks for breast cancer remain controversial. Even the effect of cigarette smoking on breast cancer development remains uncertain, as does the environmental light idea.
For a nice update and…
tsmith | June 13, 2007 Over at The Examining Room of Dr. Charles, the good doc brings up another instance of quackery from an unexpected source: Dr. Henry Heimlich, originator of the Heimlich maneuver for choking. While that procedure has clearly saved many lives, Dr. Heimlich doesn't stop there--he advocates using his maneuver for drowning victims and asthmatics, neither of which have been scientifically proven (and indeed, major medical associations have spoken out against them). Dr. Charles also reveals that Heimlich also carries out other questionable research, including deliberately infecting HIV+…
tsmith | June 6, 2007Over at her old blog, Karmen had a nice overview of Deinococcus radiodurans, a fascinating organism that's able to withstand many different extremes: genotoxic chemicals, oxidative damage, high levels of ionizing and ultraviolet radiation, dehydration, and, as the name suggests, incredibly high doses of radiation. (We're talking high--up to 5,000 Gy without breaking a sweat, while it only takes about 10 Gy to kill a human). However, despite 50 years of study, no one's really figured out just how it does it, though some clues (such as higher levels of manganese and low levels of iron) have…
tsmith | May 24, 2007 Way back in a few editions of Animalcules, several of the submissions mentioned a fungus that was killing frogs. Wednesday at the ASM meeting suggested that there may be a way to protect these amphibians:
First in a petri dish and now on live salamanders, probiotic bacteria seem to repel a deadly fungus being blamed for worldwide amphibian deaths and even extinctions. Though the research is in its early stages, scientists are encouraged by results that could lead the way to helping threatened species like mountain yellow-legged frogs of the Sierra Nevada mountains of southern California…
tsmith | May 23, 2007 Everyone knows about the "butterfly effect": the idea that a butterfly flapping its wings in Brazil could eventually result in the formation of a tornado in Texas by virtue of very small alterations in the initial conditions of a system. Though this description of it is often decried by people who study chaos theory as an inaccurate oversimplification, it's a useful illustration of the tiny perturbations that can have vast effects on a downstream chain of reactions.
When it comes to infectious diseases, climate change may be the beginning, but environmental effects extend much farther…
tsmith | May 21, 2007 I had a strange worry as a kid. I was very scared of getting bit by a tick and developing Rocky Mountain Spotted Fever (RMSF). I know, weird--even for nerdy kids like me, who knows about Rocky Mountain Spotted Fever? How many readers are even familiar with it?
For those who aren't, RMSF is a zoonotic rickettsial disease transmitted by several species of ticks. Though the disease is named after the geographical region where it was first described back in the late 1800s, the bacterium that causes it, Rickettsia rickettsii (an obligate intracellular pathogen), has been found in almost all…
tsmith | May 14, 2007 Readers may have noticed that a re-vamped "Ask a Scienceblogger" has appeared, with prior questions and responses at Cognitive Daily and Thoughts from Kansas. Aetiology gets the current installment, discussing the question, "Why is it possible to create vaccines for some microbes and not others?"
First, let me start off with a quibble about how this question was phrased, which suggests that it isn't possible to create a vaccine for some organisms. This suggests a pessimistic view not shared by researchers in the field. Just because we've not been able to create them up to this point--or…
tsmith | April 25, 2007A few readers have asked me what I thought about HIV "dissident" Peter Duesberg's recent article in Scientific American, entitled Chromosomal Chaos and Cancer. Duesberg's cancer ideas--and his claim of novelty for researching how chromosomal abnormalities, rather than more simpler gene mutations, cause cancer--are something I wanted to write about months ago, after I came across an interesting reference in this post over at Panda's Thumb, where it was noted that "...in certain kinds of cancer, chromosomal instability prevents tumourogenesis, the exact opposite of what Wells [and Duesberg--TS…
tsmith | March 30, 2007I don't know if you've seen any of the posts here at Scienceblogs or Panda's Thumb about the Discovery Institute's newest protégé, Dr. Michael Egnor. A professor of neurosurgery at SUNY-Stony Brook, Dr. Egnor has been pontificating on how "Darwinism" has nothing to offer to medicine; and indeed, that evolutionary biology has "hijacked" other fields of study. Mike has already aptly pointed out many of Egnor's strawmen and intellectual dishonesties, so I won't review them all. I've stayed out of the fray until now because I've had limited time and others have been handling it quite ably,…
tsmith | March 15, 2007 When we think of the spread of antibiotic resistance between animals and humans, we tend to think of it going from Them to Us. For example, much of the research over the past 20 years on the sub-clinical use of antibiotics in animal feed has looked how this use of antibiotics as a growth promotant breeds resistant organisms in animals, which can then enter the human population via the food we eat. Along a similar line, I just mentioned Burt's post post on cephalosporin use in cattle and the evolution of antibiotic resistance, where the worry is that use of these broad-spectrum antibiotics…
tsmith | March 13, 2007I was out yesterday, and as such missed Lynn Margulis' blog tour stop at Pharyngula. For those who may not be familiar with Margulis, she's a professor at the University of Massachusetts, Amherst, and was the one who pushed the (now accepted) idea that chloroplasts and mitochondria in cells came about due to symbiosis. In the post announcing her impending arrival, there were lots of questions about her stance on HIV/AIDS. This is mostly due to a review she co-authored on Amazon of Harvey Bialy's biography of HIV denier Peter Duesberg. The review ends: "As both Bialy and Duesberg…
tsmith | February 12, 2007I'll try to get the third installment on normal flora "basics" up tomorrow, before I spend Wednesday at Darwin Day events here in Iowa City and then the next few days at AAAS in San Francisco. In the meantime, in case you've not come across it yet, John Wilkins has been keeping an updated list of "Basics" posts here; new and notable for readers here include Shelley's post on prions and Jeremy's on ecology.