Posts Tagged ‘microbiology’
“We’ve co-evolved with our microbes”*…
Allergies seem more prevalent and more severe these days because they are. Theresa MacPhail explains…
… Although allergy researchers may disagree on definitions, symptoms and methodology, all agree on one thing: Allergies have grown worse over the last few decades, and the staggering numbers of allergy sufferers worldwide is likely to continue growing. An estimated 235 million people worldwide have asthma, and anywhere from 240 to 550 million people globally may suffer from food allergies. Drug allergy may affect up to 10% of the world’s population.
There’s a consensus, looking at the last century’s data, that U.S. hay fever rates increased in the mid-20th century. Data suggests that the incidence of asthma increased beginning in the 1960s, peaking sometime in the 1990s. Since then, asthma rates have remained fairly constant. Respiratory allergic diseases and atopic sensitization (or skin allergy) have likely increased over the last few decades. But the most dramatic and visible increase has been the rise in global incidence rates for food allergies, which began in earnest in the 1990s and has grown steadily ever since.
There are, unsurprisingly, multiple theories about the cause. The hygiene hypothesis is one front-runner, positing that people who are “too clean” develop allergies. Many others think it’s our diet, that changes in the way we grow and prepare food have altered our gut microbiome, fueling allergies. Still others argue that manmade chemicals and plastics we encounter daily are making our immune systems more irritable.
What everyone agrees on is that the environment’s influence on our genes, or epigenetics, has played a large role in the rise of allergies, as does the makeup of our nose, gut and skin microbiomes. In the end, it appears, we are at least partially doing this to ourselves. Modern living is likely at the root of the recent rise in allergies…
Our very old immune systems can’t keep up with modern lifestyles and diets, leading to increases in all sorts of chronic health problems like allergies and obesity: “How Modernity Made Us Allergic,” from @TheresaMacphail in @NoemaMag. Eminently worth reading in full.
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As we stifle a sneeze, we might send infectious birthday greetings to Alfred Hershey; he was born on this date in 1908. A bacteriologist and geneticist, investigate bacteriophages, or phages—viruses that infect and replicate inside bacteria. In 1952, he and Martha Chase conducted the famous Hershey–Chase, or “Waring Blender” experiment. Their work confirmed that DNA, not protein, was the genetic material of life.
Hershey’s work with bacteriophage earned him a share of the 1969 Nobel Prize in Physiology or Medicine with Max Delbrück and Salvador Luria, “for their discoveries concerning the replication mechanism and the genetic structure of viruses.”
“Without mysteries, life would be very dull indeed”*…
Colonoscopies are a right of passage into late middle-age. One dreads getting a “surprise”– the finding of a polyp. But one doesn’t anticipate other kinds of surprise…
Doctors in Missouri were baffled to spot a fly inside a man’s intestines during a routine colon screening.
Images taken during the colonoscopy and published in the American Journal of Gastroenterology show the intact fly inside the man’s colon.
Matthew Bechtold, the chief of Gastroenterology at the University of Missouri, told The Independent that he had prodded the fly and confirmed it was dead.
The 63-year-old patient told doctors that he had only consumed clear liquids the day before the procedure and had no idea how the fly had gotten into his colon.
He said he had eaten pizza and lettuce for dinner two days before the procedure but did not remember a fly being in his food.
The finding was described as “a very rare colonoscopy finding and mystery on how the intact fly found its way to the transverse colon.”…
Wonder never cease: “Bizarre Discovery of Intact Housefly in Man’s Intestines Shocks Doctors,” in @ScienceAlert, via @BoingBoing.
* Charles de Lint
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As we investigate intrusive insects, we might spare a thought for Seymour Benzer; he died on this date in 2007. A physicist, molecular biologist, and behavioral geneticist, he developed a method for determining the detailed structure of viral genes, did much to elucidate the nature of genetic anomalies (called nonsense mutations), and identified mutant genes useful for studying Creutzfeld-Jacob (CJ) disease and other human brain degenerative disorders… all using the ubiquitous cousin of the housefly– the fruit fly– as a research subject.
Benzer was awarded the National Medal of Science (in 1982), among many other major awards and recognitions.
“The unexamined life is not worth living”*…
Diana Gitig reports on research that suggests that some of us agree more actively with Socrates than do others– and for a baked-in reason…
People who enroll in genetic studies are genetically predisposed to do so.
According to the Catalogue of Bias, ascertainment bias occurs when a sample being studied is not representative of the target population. This can produce misleading or even false conclusions, and it can be hard to detect since it cannot usually be identified by examining the sample alone. This is why many studies try to use variables other than participation in the study to make sure their samples are as representative as possible.
Studies examining how a particular treatment affects a particular health outcome often try to handle ascertainment bias by adjusting for “covariates,” things like education level or socioeconomic status, that could affect health outcomes independently of the treatment. But Stefania Benonisdottir and Augustine Kong at Oxford’s Big Data Institute have just demonstrated that we can determine if genetic studies are biased using nothing but the genes of the participants.
And they used that technique to show that there’s a genetic contribution that influences the tendency to participate in genetic studies…
People in a genetic database have segments of DNA in common unexpectedly often: “Want to have your genes tested? It might be genetic,” in @arstechnica.
The Benonisdottir and Kong paper, in Nature Genetics, is here.
* Socrates
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As we battle bias, we might send systemic birthday greetings to Sergei Winogradsky; he was born on this date in 1856. A microbiologist, ecologist, and soil scientist, he discovered chemoautotrophy (now better known as known as chemosynthesis) and the the Nitrogen cycle— which is to say that he pioneered the cycle-of-life concept.
“There are more things in heaven and Earth, Horatio, than are dreamt of in your philosophy”*…
And some of them were recently found in the woods near Boston…
Researchers have unearthed a trove of wonders in the soil of a Massachusetts forest: an assortment of giant viruses unlike anything scientists had ever seen. The find suggests this group of relatively massive parasites has an even greater ecological diversity and evolutionary importance than researchers knew.
Giant viruses can exceed 2 micrometers in diameter, on par with some bacteria. They can also harbor immense genomes, which reach 2.5 megabases—larger than the genomes of far more complex organisms. Between the discovery of these impressively sized viruses in algae and the culturing of amoeba-infecting Mimiviruses, most of the research on the group has focused on viruses that inhabit freshwater environments. But DNA sequencing has long indicated that giant viruses are diverse and abundant elsewhere, too—especially in sediments and soils, which are estimated to host some 97% of all the viral particles on Earth. Indeed, genomic sequencing of the soils of Harvard Forest—a roughly 16-square-kilometer area west of Boston—indicated the presence of numerous, novel giant viruses.
Now, electron microscopy has allowed scientists to see what others had only sequenced. The diversity of forms was astounding, they report in a bioRxiv preprint. Not only did the researchers see the 20-sided icosahedral shapes they expected, they spotted ones with myriad modifications—tails, altered points, and multilayered or channeled structures abounded. There were even viruses with long tubular appendages, which the team dubbed “Gorgon” morphology [photo above]. Furthermore, many of these putative viral particles were coated with almost hairlike projections, which varied in length, thickness, density, and shape.
The findings suggest virologists have much to discover about how giant viruses interact with their host cells. That likely means the ecological roles these viruses play in soils—and elsewhere they’re found—are woefully underappreciated…
Microbes come in a variety of shapes, hinting at undiscovered ecological diversity: “Alien-looking viruses discovered in Massachusetts forest,” in @ScienceMagazine.
* Shakespeare, Hamlet
As we marvel at multifariousness (and note that viruses, while generally considered to be non-living and thus not considered microorganisms, are colloquially lumped in with microbes), we might spare a thought for Sidney Walter Fox; he died on this date in 1998. A biochemist, he was responsible for a series of discoveries about the origin of life. Fox believed in the process of abiogenesis, by which life spontaneously organized itself from the colloquially known “primordial soup,” poolings of various simple organic molecules that existed during the time before life on Earth. In his experiments (which possessed, he believed, conditions like those of primordial Earth), he demonstrated that it is possible to create protein-like structures from inorganic molecules and thermal energy. Dr. Fox went on to create microspheres that he said closely resembled bacterial cells and concluded that they could be similar to the earliest forms of life or protocells.
“Eventually everything connects”*…
Long-time readers will know of your correspondent’s fascination with Powers of Ten, a remarkable short film by Charles and Ray Eames, with Philip Morrison, that begins with a couple having a picnic, zooms out by “powers of ten” to the edge of the universe, then zooms in (by those same increments) to a proton.
We’ve looked before at a number of riffs on this meditation on scale: see, e.g., here, here, and here.
Now the BBC has updated the first half of Powers of Ten:
It’s a trip worth taking.
* Charles Eames
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As we wrestle with relationships, we might light a birthday candle for Sir Francis Bacon– English Renaissance philosopher, lawyer, linguist, composer, mathematician, geometer, musician, poet, painter, astronomer, classicist, philosopher, historian, theologian, architect, father of modern science (The Baconian– aka The Scientific– Method), and patron of modern democracy, whom some allege was the illegitimate son of Queen Elizabeth I of England (and others, the actual author of Shakespeare’s plays)… He was in any event born on this date in 1561.
Bacon (whose Essays were, in a fashion, the first “management book” in English) was, in Alexander Pope’s words, “the greatest genius that England, or perhaps any country, ever produced.” He probably did not actually write the plays attributed to Shakespeare (as a thin, but long, line of enthusiasts, including Mark Twain and Friedrich Nietzsche, believed). But Bacon did observe, in a discussion of sedition that’s as timely today as ever, that “the remedy is worse than the disease.”
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