Archive for the ‘Biology’ Category

The secret of how the Venus flytrap “remembers” when it captures prey

October 20th, 2020

Scientists genetically altered a Venus flytrap so that it glows green in response to outside stimulation, yielding important clues about how the plant's short-term "memory" works.

Scientists are continuing to tease out the mechanisms by which the Venus flytrap can tell when it has captured a tasty insect as prey as opposed to an inedible object (or just a false alarm). There is evidence that the carnivorous plant has something akin to a short-term "memory," and a team of Japanese scientists has found evidence that the mechanism for this memory lies in changes in calcium concentrations in its leaves, according to a recent paper published in the journal Nature Plants.

The Venus flytrap attracts its prey with a pleasing fruity scent. When an insect lands on a leaf, it stimulates the highly sensitive trigger hairs that line the leaf. When the pressure becomes strong enough to bend those hairs, the plant will snap its leaves shut and trap the insect inside. Long cilia grab and hold the insect in place, much like fingers, as the plant begins to secrete digestive juices. The insect is digested slowly over five to 12 days, after which the trap reopens, releasing the dried-out husk of the insect into the wind.

Back in 2016, a team of German scientists discovered that the Venus flytrap can actually "count" the number of times something touches its hair-lined leaves—an ability that helps the plant distinguish between the presence of prey and a small nut or stone, or even a dead insect. The scientists zapped the leaves of test plants with mechano-electric pulses of different intensities and measured the responses. It turns out that the plant detects that first "action potential" but doesn't snap shut right away, waiting until a second zap confirms the presence of actual prey, at which point the trap closes.

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Posted in Biology, botany, phase transitions, plant biology, plants, science, venus flytrap | Comments (0)

Bats, bugs, and beauty: The best microscopy images of 2020

October 13th, 2020
Image of a series of colored loops.

Enlarge / While this may look like a set of iridescent satin ribbons, it's actually the scales on the wing of a butterfly. (credit: Don Komarechka)

I don't know how many years I've been putting together image galleries of the Nikon Small World Microscopy contest, but it has been quite a few now, and it is hard not to feel like I'm repeating the same things when I introduce a selection of the images from it: that nature's beauty isn't limited to grand landscapes or charismatic megafauna. That serious science can co-exist with amazing aesthetics. That some of the best scientists also have an eye for the artistic and the desire to capture the worlds they study in compelling ways. That technology and software have revolutionized a technology—the microscope—that has been around for hundreds of years.

All of those things are still true, which is why I keep emphasizing them. But words are just a distraction from the pure artistry of this year's contest winners. So I'll shut up and let you enjoy them.

 

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Posted in Biology, materials, microscopy, science | Comments (0)

US states stopped their pandemic social restrictions too soon

October 8th, 2020
A masked man and woman walks outside a plastic barrier.

Enlarge / If you can't socially distance, a face mask helps. (credit: Christopher Furlong / Getty Images)

Many countries that controlled their COVID-19 cases in the spring are now seeing rises in infections, raising the prospect that they'll face a second wave of cases, as many epidemiological models had predicted. But in the United States, the number of cases has never dropped to low levels. Instead, it varied between high levels of infection and very high peaks in cases. Why is everything so different in the states?

While there are plenty of possible reasons, a series of new studies essentially blame all the obvious ones: the United States ended social distancing rules too soon, never built up sufficient testing and contact-tracing capabilities, and hasn't adopted habits like mask use that might help substitute for its failures elsewhere. The fact that some of these studies used very different methods to arrive at similar conclusions suggests that those conclusions are likely to hold up as more studies come in.

Too soon

One of the studies, performed by a US-South African team, looked at the relaxation of social distancing rules in the US. Its authors created a list of restrictions for each state and the District of Columbia and tracked the number of COVID-19 deaths in each state for eight weeks prior to the rules being terminated. The number of deaths was used as a proxy for the total number of cases, as the erratic availability of tests made the true infection rate difficult to determine.

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Posted in Biology, COVID-19, epidemiology, medicine, pandemic, public health, SARS-CoV-2, science | Comments (0)

Gene-editing tool gets its inevitable Nobel

October 7th, 2020
Emmanuelle Charpentier reminds everybody about pandemic safety at the start of a press conference following the announcement of her Nobel Prize.

Enlarge / Emmanuelle Charpentier reminds everybody about pandemic safety at the start of a press conference following the announcement of her Nobel Prize. (credit: Pictures Alliance/Getty Images)

On Wednesday, the Nobel Prize Committee awarded the Chemistry Nobel to Emmanuelle Charpentier and Jennifer Doudna, who made key contributions to the development of the CRISPR gene-editing system, which has been used to produce the first gene-edited humans. This award may spur a bit of controversy, as there were a lot of other contributors to the development of CRISPR (enough to ensure a bitter patent fight), and Charpentier and Doudna's work was well into the biology side of chemistry. But nobody's going to argue that the gene editing wasn't destined for a Nobel Prize.

Basic science

The history of CRISPR gene editing is a classic story of science: a bunch of people working in a not-especially cutting-edge area of science found something strange. The "something" in this case was an oddity in the genome sequences of a number of bacteria. Despite being very distantly related, the species all had a section of the genome where a set of DNA sequences were repeated, with a short spacer in between them. The sequences picked up the name CRISPR for "clustered regularly interspaced short palindromic repeats," but nobody knew what they were doing there.

The fact that they might be important became apparent when researchers recognized that bacteria that had CRISPR sequences invariably also had a small set of genes associated with them. Since bacteria tended to rapidly lose genes and repeat sequences that weren't performing useful functions, this obviously implied some sort of utility. But it took 18 years for someone to notice that the repeated sequences matched those found in the genomes of viruses that infected the bacteria.

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Posted in Biology, chemistry, CRISPR, gene editing, Nobel prize, science | Comments (0)

A decadeslong struggle to find a virus wins the Nobel

October 5th, 2020
Image of a statue of a person, with a poster in the background.

Enlarge / This photograph of a bust of Alfred Nobel was taken just prior to the announcement of the winners of the 2020 Nobel Prize in Physiology or Medicine at the Karolinska Institute in Stockholm, Sweden, on October 5, 2020. (credit: JONATHAN NACKSTRAND / Getty Images)

The first known human cases of COVID-19 occurred in December 2019. About a month went by before the virus was identified and its complete genome sequence identified. This year's Nobel Prize in Physiology or Medicine honors a 25-year-long struggle to identify the virus we now know as hepatitis C.

The A B Cs

The hepatitis viruses are a bit confusing. There are now five of them known, and while they're united by their ability to attack the liver, they're very different in most other ways. The most significant of the viruses are hepatitis A, hepatitis B, and hepatitis C, and they're caused by three largely unrelated viruses—some even differ in their genetic material, using DNA versus RNA—with very different properties.

One of the first differences recognized by the medical research community was how the viruses spread. Hepatitis A infections can start due to contaminated water or food; in contrast, B and C are typically spread through contaminated blood or needles, making them a threat to the blood supply. The hepatitis A virus was the first identified, leaving researchers focused on the bloodborne B and C. B was the next identified, which is when this year's Nobel Laureates enter the picture.

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Posted in Biology, Hepatitis C, medicine, Nobel prize, science, virology | Comments (0)

Chitin could be used to build tools and habitats on Mars, study finds

September 22nd, 2020
A figurine of an astronaut stands next to a block.

Enlarge / Scientists mixed chitin—an organic polymer found in abundance in arthropods, as well as fish scales—with a mineral that mimics the properties of Martian soil to create a viable new material for building tools and shelters on Mars. (credit: Javier G. Fernandez)

Space aficionados who dream of one day colonizing Mars must grapple with the stark reality of the planet's limited natural resources, particularly when it comes to building materials. A team of scientists from the Singapore University of Technology and Design discovered that, using simple chemistry, the organic polymer chitin—contained in the exoskeletons of insects and crustaceans—can easily be transformed into a viable building material for basic tools and habitats. This would require minimal energy and no need for transporting specialized equipment. The scientists described their experiments in a recent paper published in the journal PLOS ONE.

"The technology was originally developed to create circular ecosystems in urban environments," said co-author Javier Fernandez. "But due to its efficiency, it is also the most efficient and scalable method to produce materials in a closed artificial ecosystem in the extremely scarce environment of a lifeless planet or satellite."

As we previously reported, NASA has announced an ambitious plan to return American astronauts to the Moon and establish a permanent base there, with an eye toward eventually placing astronauts on Mars. Materials science will be crucial to the Artemis Moon Program's success, particularly when it comes to the materials needed to construct a viable lunar (or Martian) base. Concrete, for instance, requires a substantial amount of added water in order to be usable in situ, and there is a pronounced short supply of water on both the Moon and Mars. And transport costs would be prohibitively high. NASA estimates that it costs around $10,000 to transport just one pound of material into orbit. 

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Posted in Artemis Moon Program, biochemistry, Biology, biomimicry, chitin, Mars, materials science, NASA, science, space colonization | Comments (0)

When building an embryo, timing is everything

September 19th, 2020
The repeated light and dark pattern you can see down the side of this embryo is caused by the presence of somites.

The repeated light and dark pattern you can see down the side of this embryo is caused by the presence of somites. (credit: Flickr user Lunar Caustic)

There's a bit of a problem in biology that's so obvious that most biologists don't end up thinking of it as a problem. Humans and mice (and most other mammals) all make pretty much the same collection of stuff as they develop from a fertilized egg. And they do that using a near-identical set of genes. But mice do it all in 21 days; it takes humans over 10 times longer to do it.

You might try to ascribe that to the different number of cells, but as you move across the diversity of mammals, none of that really lines up. Things get even more confusing when you try to account for things like birds and reptiles, which also use the same genes to make many of the same things. The math just doesn't work out. How do developing organisms manage to consistently balance cell number, development time, and a static network of genes?

Biologists are just starting to figure that out, and two papers published this week mark some major progress in the field.

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Posted in Biology, developmental biology, embryo, science, spinal cord, vertebrae | Comments (0)

Chemical that shouldn’t be there spotted in Venus’ atmosphere

September 14th, 2020
Image of a pale circle with irregular lines in front of it.

Enlarge / The spectral signature of phosphine superimposed on an image of Venus. (credit: ALMA (ESO/NAOJ/NRAO), Greaves et al. & JCMT)

Today, researchers are announcing that they've observed a chemical in the atmosphere of Venus that has no right to be there. The chemical, phosphine (a phosphorus atom hooked up to three hydrogens), would be unstable in the conditions found in Venus' atmosphere, and there's no obvious way for the planet's chemistry to create much of it.

That's leading to a lot of speculation about the equally unlikely prospect of life somehow surviving in Venus' upper atmosphere. But a lot about this work requires input from people not involved in the initial study, which today's publication is likely to prompt. While there are definitely reasons to think phosphine is present on Venus, its detection required some pretty involved computer analysis. And there are definitely some creative chemists who are going to want to rethink the possible chemistry of our closest neighbor.

What is phosphine?

Phosphorus is one row below nitrogen on the periodic table. And just as nitrogen can combine with three hydrogen atoms to form the familiar ammonia, phosphorus can bind with three hydrogens to form phosphine. Under Earth-like conditions, phosphine is a gas, but not a pleasant one: it's extremely toxic and has a tendency to spontaneously combust in the presence of oxygen. And that later feature is why we don't see much of it today; it's simply unstable in the presence of any oxygen.

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Posted in Biology, exobiology, Life, planetary science, science, Venus | Comments (0)

Russian vaccine trial data has some odd-looking data [Updated]

September 5th, 2020
Image of a women in medical protective gear holding a box of samples.

Enlarge / MOSCOW, RUSSIA - SEPTEMBER 4, 2020: Medical staff with newly delivered boxes containing COVID-19 vaccine in a cold room at No2 Outpatient Clinic in southern Moscow. (credit: Stanislav Krasilnikov / Getty Images)

Update, September 9, 2020: On Monday, Enrico Bucci published an open letter outlining some concerns with the data in The Lancet paper that describes the vaccine safety tests. Bucci is an adjunct professor at Temple University who also runs a company that focuses on research integrity, so he has some history in this area. His open letter highlights a number of instances in the paper where the data for different samples produces identical or near-identical results.

While a few instances of this might be expected due to the similarities between the experiments and the small population of participants, the large number of such cases is highly unusual. And, as Bucci notes, the raw data underlying these graphs has not been made available, making it impossible to identify any innocuous reasons the results are so similar.

The letter simply calls the issue to the attention of the editors at The Lancet, where the study was published. As of today, 25 additional professors have signed it.

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Posted in Biology, COVID-19, medicine, SARS-CoV-2, science, vaccines, virology | Comments (0)

Evidence slowly building for long-term heart problems post-COVID-19

September 3rd, 2020
Image of small blue spheres surrounded by long green fibers.

Enlarge / A fluorescent image of cardiac muscle cells in culture. (credit: Douglas B. Cowan and James D. McCully, Harvard Medical School)

Coronaviruses spread primarily through material released when we breathe, and they cause respiratory symptoms. And SARS-CoV-2, with part of its name coming from "severe acute respiratory syndrome," didn't appear to be an exception. But as time went on, additional symptoms became clear—loss of smell, digestive-tract issues—and these weren't likely to be due to infection of the respiratory tract. And over time, what also became apparent is that the symptoms didn't necessarily fade when the virus was cleared.

As we've studied the virus more, we've learned that the protein it uses to latch on to cells is present in a lot of different tissues in the body, suggesting that a wide variety of different effects could be the direct product of infections of the cells there. This week, the effect that seems to be grabbing attention is heart problems, spurred by a Scientific American article that (among other things) considers the stories of professional and college athletes who have been infected. That was followed by a report that roughly 30 percent of college athletes who've contracted the virus end up with inflammation of the heart muscle called myocarditis.

Both reports are heavy on anecdote, but this is not a new thing; ESPN had reported on myocarditis in college athletes back in early August. And, more significantly, the scientific community has been looking into the issue for months. So far, its conclusion is that there are likely to be heart complications, even in patients who had mild COVID-19 symptoms. But the long-term implications of these problems aren't yet clear.

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Posted in Biology, cardiac, COVID-19, heart, medicine, SARS-CoV-2, science | Comments (0)