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New evolutionary lab experiment confirms Darwin Devolves: The citrate death spiral

Michael Behe
Evolution News
Wed, 17 Jun 2020 18:14 UTC
Richard Lenski
© Zachary Blount [CC BY-SA 4.0], from Wikimedia Commons
Richard Lenski
Michigan State University biologist Richard Lenski and collaborators have just published a terrific new paper in the journal eLife.1 Anyone who wants to see a crystal-clear example of the inherent, unavoidable, fatal difficulties that the Darwinian mechanism itself poses for unguided evolution should read it closely.

The paper concerns the further evolution of a widely discussed mutant strain of the bacterium E. coli discovered during the course of Lenski's Long Term Evolution Experiment (LTEE). The LTEE is his more-than-three-decades-long project in which E. coli was allowed to grow continuously in laboratory flasks simply to observe how it would evolve.2 As I've written before, almost all of the beneficial mutations that were discovered to have spread through the populations of bacteria in the LTEE were ones that either blunted pre-existing genes (decreasing their previous biochemical activity) or outright broke them.3

An Interesting Exception?

There seemed, however, to be one interesting exception.4 One morning after more than 30,000 generations of bacterial growth, one flask of E. coli (out of 12 separate flasks that Lenski maintained for comparison and replication's sake) seemed cloudier than the other 11 flasks. That indicated substantially more bacteria than usual had grown in the nutrient broth. After much hard laboratory work, Lenski's group showed that a region of the prodigious bacterium's DNA that was close to a gene coding for a citrate transporter (that is, a protein whose job is to bring external, dissolved citrate into the cell; citrate is a common chemical that cells metabolize) had duplicated.5 The duplication mutation placed the control region of a different gene next to that of the citrate transporter.
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Comet 2

New Comet C/2020 K8 (CATALINA-ATLAS)

Ernesto Guido
Remanzacco Blogspot
Wed, 17 Jun 2020 17:12 UTC
CBET 4796 & MPEC 2020-L46, issued on 2020, June 12, announce the independent discovery of a comet (magnitude ~19) of an apparently asteroidal object made on CCD images taken with the 0.68-m Schmidt telescope of the Catalina Sky Survey (on May 25, 28, and 29) and the 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program (on June 7). Then on June 8, R. Weryk reported the linkage of all of these tracklets, suggesting it might possibly be a comet based upon the astrometry. The object has been found to show cometary appearance subsequently by numerous CCD astrometrists at other observing sites after the object was posted on the Minor Planet Center's PCCP webpage. The new comet has been designated C/2020 K8 (CATALINA-ATLAS).
We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 29 unfiltered exposures, 60 seconds each, obtained remotely on 2020, June 09.4 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a diffuse irregular coma about 10" in diameter (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini).

Stacking of 24 unfiltered exposures, 57 seconds each, obtained remotely on 2020, June 10.4 from U69 (iTelescope, Auberry California) through a 0.61-m f/6.5 astrograph + CCD, shows that this object is a comet with a diffuse coma about 15" in diameter slightly elongated toward PA 358 (Observers A. Valvasori, E. Guido).

Our confirmation images (click here for a bigger version)
Comet C/2020 K8 Catalina-Atlas
© Remanzacco Blogspot
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Blue Planet

There could be up to 6 billion Earth-like planets out there in the Milky Way

Michelle Starr
Science Alert
Wed, 17 Jun 2020 17:03 UTC
solar systems
© ESO/M. Kornmesser
There's only one planet we know of in the entire Universe that's capable of hosting life. That's Earth. So, when we search for exoplanets that might host life, it's pretty much what we look for: a rocky exoplanet orbiting a Sun-like star at a distance that is neither too hot nor too cold for liquid water on the surface.

To try to figure out the probability of life elsewhere in the Milky Way, one has to start with a reasonable estimate of how many exoplanets are out there that fit such a bill.

Now, with years of exoplanet-hunting data in the bag, astronomers have made a new calculation and determined there could be as many as 6 billion Earth-like planets orbiting Sun-like stars in the Milky Way.

"My calculations place an upper limit of 0.18 Earth-like planets per G-type star," said astronomer Michelle Kunimoto from the University of British Columbia (UBC) in Canada. (You may remember that Kunimoto discovered a whopping 17 exoplanets in Kepler data quite recently.)
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Easter Egg

New study suggests that hard eggshells developed at least three times in the dinosaur family tree


PhysOrg
Wed, 17 Jun 2020 15:43 UTC
fossilized Protoceratops eggs dinosaurs
© M. Ellison/AMNH
The clutch of fossilized Protoceratops eggs and embryos examined in this study was discovered in the Gobi Desert of Mongolia at Ukhaa Tolgod.
New research suggests that the first dinosaurs laid soft-shelled eggs — a finding that contradicts established thought. The study, led by the American Museum of Natural History and Yale University and published today in the journal Nature, applied a suite of sophisticated geochemical methods to analyze the eggs of two vastly different non-avian dinosaurs and found that they resembled those of turtles in their microstructure, composition, and mechanical properties. The research also suggests that hard-shelled eggs evolved at least three times independently in the dinosaur family tree.

"The assumption has always been that the ancestral dinosaur egg was hard-shelled," said lead author Mark Norell, chair and Macaulay Curator in the Museum's Division of Paleontology. "Over the last 20 years, we've found dinosaur eggs around the world. But for the most part, they only represent three groups — theropod dinosaurs, which includes modern birds, advanced hadrosaurs like the duck-bill dinosaurs, and advanced sauropods, the long-necked dinosaurs. At the same time, we've found thousands of skeletal remains of ceratopsian dinosaurs, but almost none of their eggs. So why weren't their eggs preserved? My guess — and what we ended up proving through this study — is that they were soft-shelled."
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Info

Huge circular arc discovered near the Big Dipper

Monica Young
Sky & Telescope
Tue, 16 Jun 2020 08:15 UTC
The 30-degree arc is likely a shock front expanding from a star that exploded some 100,000 years ago.

Circular Arc near Big Dipper
© Sky & Telescope
An oddly perfect puddle of hydrogen gas lies splashed just outside the bowl of the Big Dipper. Yet even though it spans a third of the northern sky, you'd never see it visually through your telescope.

Ultraviolet and narrowband photography have captured the thin and extremely faint trace of hydrogen gas arcing across 30°. The arc, presented at the recent virtual meeting of the American Astronomical Society, is probably the pristine shockwave expanding from a supernova that occurred some 100,000 years ago, and it's a record-holder for its sheer size on the sky.

Andrea Bracco (University of Paris) and colleagues came upon the Ursa Major Arc serendipitously when looking through the ultraviolet images archived by NASA's Galaxy Evolution Explorer (GALEX). They were looking for signs of a straight, 2° filament that had been observed two decades ago — but they found out that that length of gas was less straight than they thought, forming instead a small piece of a much larger whole. The researchers report the arc in the April issue of Astronomy & Astrophysics.
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Galaxy

Comet NEOWISE could become naked-eye by July, Earth crossing heliospheric current sheet boundary


Space Weather
Tue, 16 Jun 2020 22:32 UTC
NEOWISE
© Michael Mattiazzo on June 10, 2020 @ Swan Hill, Australia
This image of comet C/2020 F3 (NEOWISE) was taken on 2020 June 10 at 08:30UT Using a Celestron C11 RASA f/2.2 on a Skywatcher AZEQ6 mount and Canon 6D camera, 4x30sec combined exposure. The comets solar elongation was a mere 21 degrees! The comets altitude above local horizon was 5 degrees. My approximate visual estimate was 6.8 using 15x70mm binoculars. The well condensed coma was 4' wide. Tail length on image = >40' in PA 149. Heliocentric distance = 0.72AU Earth distance = 1.56AU Hopefully the comet will survive perihelion and be a case of third time lucky for northern hemisphere observers.
NAKED-EYE COMET NEOWISE?

Here we go again. A comet is falling toward the sun, and it could become a naked-eye object after it skims past the orbit of Mercury on July 3rd. Michael Mattiazzo photographed Comet NEOWISE (C/2020 F3) on June 10th from Swan Hill, Australia.

"Pushing the limits of comet observing, I had to leave home to find a clear horizon," says Mattiazzo. "When I took the picture, Comet NEOWISE was very close to the sun and only 5 degrees above the local horizon. Its visual magnitude was near +7.0, below the threshold for naked-eye visibility."

It might not look like much now, but this comet could blossom in the weeks after perihelion (closest approach to the sun). Forecasters say Comet NEOWISE might become as bright as a 2nd or 3rd magnitude star. Northern hemisphere observers would be able to easily see it in the evening sky in mid-July.

Comment: See also:

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Blue Planet

As many as six billion Earth-like planets in our galaxy, according to new estimates


Phys Org
Tue, 16 Jun 2020 22:28 UTC
Kepler telescope
© NASA Ames/W Stenzel
Artist's conception of Kepler telescope observing planets transiting a distant star.
To be considered Earth-like, a planet must be rocky, roughly Earth-sized and orbiting Sun-like (G-type) stars. It also has to orbit in the habitable zones of its star — the range of distances from a star in which a rocky planet could host liquid water, and potentially life, on its surface.

"My calculations place an upper limit of 0.18 Earth-like planets per G-type star," says UBC researcher Michelle Kunimoto, co-author of the new study in The Astronomical Journal. "Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets."

According to UBC astronomer Jaymie Matthews: "Our Milky Way has as many as 400 billion stars, with seven percent of them being G-type. That means less than six billion stars may have Earth-like planets in our Galaxy."

Previous estimates of the frequency of Earth-like planets range from roughly 0.02 potentially habitable planets per Sun-like star, to more than one per Sun-like star.
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Microscope 2

Coronavirus mutation significantly increases its ability to infect cells


Technology Networks
Sun, 14 Jun 2020 00:00 UTC
coronavirus, mutations coronavirus
A tiny genetic mutation in the SARS coronavirus 2 variant circulating throughout Europe and the United States significantly increases the virus' ability to infect cells, lab experiments performed at Scripps Research show.

"Viruses with this mutation were much more infectious than those without the mutation in the cell culture system we used," says Scripps Research virologist Hyeryun Choe, PhD, senior author of the study.

The mutation had the effect of markedly increasing the number of functional spikes on the viral surface, she adds. Those spikes are what allow the virus to bind to and infect cells.

"The number — or density — of functional spikes on the virus is 4 or 5 times greater due to this mutation," Choe says.

The spikes give the coronavirus its crown-like appearance and enable it to latch onto target cell receptors called ACE2. The mutation, called D614G, provides greater flexibility to the spike's "backbone," explains co-author Michael Farzan, PhD, co-chairman of the Scripps Research Department of Immunology and Microbiology.

Comment: See also:

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Cassiopaea

Bright light of novae come from shockwaves and not from thermo-nuclear explosions says new study


University of Copenhagen
Thu, 11 Jun 2020 20:34 UTC
V906 Carinae
© Copyright 2018 by W. Paech + F. Hofmann, Team Chamaeleon, Chamaeleon and Onjala Observatory, Namibia
Image of V906 Carinae about 18 days after its discovery.
Astronomers have long believed that the bright light of novae comes from thermo-nuclear explosions. Now, an international team, including researchers from the University of Copenhagen, has for the first time demonstrated that most of their brightness comes from shockwaves created in a unique and a previously unknown process. The finding ends a decades-old understanding of novae — and may help solve one of the greatest riddles in astrophysics.

Classical novae have been among the most extensively studied astrophysical phenomena since humans first began wondering about twinkling points in the night sky. Yet we continue to learn new things, as evidenced by new research conducted by the University of Copenhagen, among others.

Novae are explosions that occur when a white dwarf star and its companion star in a binary system orbit closer and closer around one another. As the two stars approach, gas from the companion star is stripped away and onto the white dwarf's surface, where it builds up like a gas shell. Eventually, after thousands of years, the piled up gas shell explodes in a nuclear fusion reaction.

For decades, astronomers believed that this thermo-nuclear explosive event is what caused white dwarves to suddenly shine up to a million times brighter — making them appear to be entirely new stars. Hence the name 'nova', meaning 'new' in Latin. But now, for the first time, an international team of researchers has demonstrated that it is the "shock", not the explosion itself, which mainly causes a nova to blaze brightly in the night sky.

"It's a whole new understanding of how a nova works. Indeed, it changes the more than 45-year-old perception that novae only get their light from the nuclear reaction," states Luca Izzo, co-author of the study — now published in Nature Astronomy. Izzo is an astrophysicist and post-doctoral fellow at the University of Copenhagen's Niels Bohr Institute.

The new evidence comes from observations of 'V906 Carina', a nova discovered in 2018 roughly 13,000 light-years from Earth.
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Arrow Up

New study explores the mystery of what forces drive Earth's mountains to reach great heights


Sputnik
Mon, 15 Jun 2020 08:35 UTC
Mountains clouds
© CC BY-SA 3.0/Rick Shu
Morning Cloud Panorama
Scientists have long been engaged in a debate on what factors impact the growth of mountains - a process quite fascinating for science, albeit lengthy, and often taking billions of years.

A new study claims to have revealed the main driving force behind the growth of mountains, which regulates how big they become.

According to the research published in Nature on 11 June, "megathrust shear force controls mountain height at convergent plate margins", and tectonic forces underneath mountains determine to what dimensions they grow. Thus, for mountains located near tectonic plate collision zones, maximum mountain height is chiefly decided by an equilibrium of forces within Earth's crust, and not by any weathering or erosion on top.

The team of German scientists, led by Armin Dielforder of the Helmholtz Centre Potsdam, the GFZ German Research Centre for Geosciences, Ralf Hetzel of the Institute of Geology and Palaeontology, the University of Münster, and Onno Oncken, Helmholtz Centre Potsdam, the GFZ German Research Centre for Geosciences, analysed the strength of specific plate boundaries and modeled the forces that would be acting on the tectonic plates. In part they used heat flow measurements near the surface as a proxy for the frictional energy that comes into play during the process.
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