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Discovery Supports a Surprising New View of How Life on Earth Originated

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Newly described chemical reaction could have assembled DNA building blocks before life forms and their enzymes existed.

Discovery boosts theory that life on our planet arose from RNA-DNA mix.

Chemists at Scripps Research have made a discovery that supports a surprising new view of how life originated on our planet.

In a study published in the chemistry journal Angewandte Chemie, they demonstrated that a simple compound called diamidophosphate (DAP), which was plausibly present on Earth before life arose, could have chemically knitted together tiny DNA building blocks called deoxynucleosides into strands of primordial DNA.

The finding is the latest in a series of discoveries, over the past several years, pointing to the possibility that DNA and its close chemical cousin RNA arose together as products of similar chemical reactions, and that the first self-replicating molecules — the first life forms on Earth — were mixes of the two.

The discovery may also lead to new practical applications in chemistry and biology, but its main significance is that it addresses the age-old question of how life on Earth first arose. In particular, it paves the way for more extensive studies of how self-replicating DNA-RNA mixes could have evolved and spread on the primordial Earth and ultimately seeded the more mature biology of modern organisms.

“This finding is an important step toward the development of a detailed chemical model of how the first life forms originated on Earth,” says study senior author Ramanarayanan Krishnamurthy, PhD, associate professor of chemistry at Scripps Research.

The finding also nudges the field of origin-of-life chemistry away from the hypothesis that has dominated it in recent decades: The “RNA World” hypothesis posits that the first replicators were RNA-based, and that DNA arose only later as a product of RNA life forms.

Is RNA too sticky?

Krishnamurthy and others have doubted the RNA World hypothesis in part because RNA molecules may simply have been too “sticky” to serve as the first self-replicators.

A strand of RNA can attract other individual RNA building blocks, which stick to it to form a sort of mirror-image strand — each building block in the new strand binding to its complementary building block on the original, “template” strand. If the new strand can detach from the template strand, and, by the same process, start templating other new strands, then it has achieved the feat of self-replication that underlies life.

But while RNA strands may be good at templating complementary strands, they are not so good at separating from these strands. Modern organisms make enzymes that can force twinned strands of RNA — or DNA — to go their separate ways, thus enabling replication, but it is unclear how this could have been done in a world where enzymes didn’t yet exist.

A chimeric workaround

Krishnamurthy and colleagues have shown in recent studies that “chimeric” molecular strands that are part DNA and part RNA may have been able to get around this problem, because they can template complementary strands in a less-sticky way that permits them to separate relatively easily.

The chemists also have shown in widely cited papers in the past few years that the simple ribonucleoside and deoxynucleoside building blocks, of RNA and DNA respectively, could have arisen under very similar chemical conditions on the early Earth.

Moreover, in 2017 they reported that the organic compound DAP could have played the crucial role of modifying ribonucleosides and stringing them together into the first RNA strands. The new study shows that DAP under similar conditions could have done the same for DNA.

“We found, to our surprise, that using DAP to react with deoxynucleosides works better when the deoxynucleosides are not all the same but are instead mixes of different DNA ‘letters’ such as A and T, or G and C, like real DNA,” says first author Eddy Jiménez, PhD, a postdoctoral research associate in the Krishnamurthy lab.

“Now that we understand better how a primordial chemistry could have made the first RNAs and DNAs, we can start using it on mixes of ribonucleoside and deoxynucleoside building blocks to see what chimeric molecules are formed — and whether they can self-replicate and evolve,” Krishnamurthy says.

He notes that the work may also have broad practical applications. The artificial synthesis of DNA and RNA — for example in the “PCR” technique that underlies COVID-19 tests — amounts to a vast global business, but depends on enzymes that are relatively fragile and thus have many limitations. Robust, enzyme-free chemical methods for making DNA and RNA may end up being more attractive in many contexts, Krishnamurthy says.

Reference: “Prebiotic Phosphorylation and Concomitant Oligomerization of Deoxynucleosides to form DNA” by Eddy Jiménez, Clémentine Gibard and Ramanarayanan Krishnamurthy, 15 December 2020, Angewandte Chemie.
DOI: 10.1002/anie.202015910

Funding was provided by the Simons Foundation.

Source: – SciTechDaily

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100-million-year old beetle fossil sheds light on family of ancient bugs – CNET

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A close-up view of the well-preserved Cretophengodes azari, a fossil light-producing beetle encased in amber.


Chenyang Cai

A beetle trapped in amber for over 100 million years is offering scientists clues to why the bioluminescent insects may have glowed way back during the Cretaceous period, about 145 to 66 million years ago. 

In a new study published in the journal Proceedings of the Royal Society B, scientists reveal that a Cretophengodes beetle found “preserved with life-like fidelity in amber” has a direct connection to its firefly cousins. 

It’s been a bit of a mystery to scientists why ancient beetles could glow. But based on their distant relatives like fireflies, scientists believe the function could likely have been used as a defense against predators, as well as a way to attract mates — much like the modern-day beetle larvae in the same family have used light.

“The discovery of a new extinct Elateroid beetle family is significant,” study co-author Erik Tihelka from the School of Earth Sciences said in a statement, “because it helps shed light on the evolution of these fascinating beetles.” 

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Here’s an artistic reconstruction of a Cretophengodes azari male and female in the undergrowth of a Cretaceous rainforest.


Dinghua Yang

Because this particular beetle fossil was well-preserved in amber, scientists were able to see the light organ on the abdomen of the male beetle. That provides proof adult Cretophengodes were able to produce light, some 100 million years ago.

The majority of light-producing beetles belong to the Elateroidea family, which has over 24,000 known species. The discovery of this beetle provides the missing fossil link between living families, and in doing so helps scientists understand how these beetles evolved and how they should be classified.

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With the recent launch of Starlink, SpaceX set a record for rapid reuse – Sunday Vision

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Zoom in / Falcon 9, Booster 1051, broke the sound barrier on December 13, 2020. It was back again for its eighth launch a little over a month later.

SpaceX continues to make strides as it pushes the boundaries of reusing the Falcon 9 first stage rocket.

On Wednesday morning, the company plans to launch the next batch of 60 Starlink satellites, and reuse the booster number 1051. This will in fact be the eighth flight of this Falcon 9 rocket – setting a new record for the number of uses for any single rocket core. SpaceX expects to reach 10 uses of at least one stage of the Falcon 9 later this year.

The next launch attempt is also noteworthy as it would mark a rapid turnaround for this first phase. The missile last flew on December 13, launching the Sirius XM-7 mission in geostationary transport orbit. This 38-day period will significantly eclipse the previous Falcon 9 Phase 1 transformation margin, which is 51 days. This indicates that the company’s engineers and technicians are continuing to learn best practices for recovering and refurbishing the missiles.

The Starlink mission is scheduled to launch at 8:02 AM EST (13:02 UTC) on Wednesday from the Cape Canaveral Space Force Station in Florida. Its launch was originally delayed by 24 hours from Monday due to unfavorable weather conditions in the offshore recovery area, where Just read the instructions Will wait for the return of the first stage. Then the important company delayed an additional day, say More time was needed for “pre-launch inspections”. It is not clear if this refers to the missile or the payload.

This will be the sixteenth launch of “operational” Starlink satellites, in addition to an earlier launch of experimental satellites. This mission is already the largest satellite operator in the world, and will bring the total number of Starlink satellites launched by SpaceX to over 1,000. Some of these satellites are no longer operational, are in the process of exiting orbit, or have already done so.

In starting to build this constellation, SpaceX owns it Introducing a public beta To define the regions of North America and is expected to offer broader coverage later this year. First impressions It was generally positive.

At the same time, SpaceX is also working to address the concerns of scientists who are concerned that large constellations of satellites transmitting the Internet from space will distort the night sky and damage astronomical observations. Last year, the company started adding “masks” to reduce the reflection of its satellites. However, Recent analysis From these “DarkSats” they indicate that more effort may be required.

Weather conditions for launch on Wednesday appear favorable for the mission, both at the launch site and in the recovery area. SpaceX should start live 15 minutes before take off.

[embedded content]

Starlink launched.

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All-purpose dinosaur opening reconstructed – Science Daily

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For the first time ever, a team of scientists, led by the University of Bristol, have described in detail a dinosaur’s cloacal or vent — the all-purpose opening used for defecation, urination and breeding.

Although most mammals may have different openings for these functions, most vertebrate animals possess a cloaca.

Although we know now much about dinosaurs and their appearance as feathered, scaly and horned creatures and even which colours they sported, we have not known anything about how the vent appears.

Dr Jakob Vinther from the University of Bristol’s School of Earth Sciences, along with colleagues Robert Nicholls, a palaeoartist, and Dr Diane Kelly, an expert on vertebrate penises and copulatory systems from the University of Massachusetts Amherst, have now described the first cloacal vent region from a small Labrador-sized dinosaur called Psittacosaurus, comparing it to vents across modern vertebrate animals living on land.

Dr Vinther said: “I noticed the cloaca several years ago after we had reconstructed the colour patterns of this dinosaur using a remarkable fossil on display at the Senckenberg Museum in Germany which clearly preserves its skin and colour patterns.

“It took a long while before we got around to finish it off because no one has ever cared about comparing the exterior of cloacal openings of living animals, so it was largely unchartered territory.”

Dr Kelly added: “Indeed, they are pretty non-descript. We found the vent does look different in many different groups of tetrapods, but in most cases it doesn’t tell you much about an animal’s sex.

“Those distinguishing features are tucked inside the cloaca, and unfortunately, they’re not preserved in this fossil.”

The cloaca is unique in its appearance but exhibits features reminiscent to living crocodylians such as alligators and crocodiles, which are the closest living relatives to dinosaurs and other birds.

The researchers note that the outer margins of the cloaca are highly pigmented with melanin. They argue that this pigmentation provided the vent with a function in display and signalling, similar to living baboons and some breeding salamanders.

The authors also speculate that the large, pigmented lobes on either side of the opening could have harboured musky scent glands, as seen in living crocodylians.

Birds are one the few vertebrate groups that occasionally exhibit visual signalling with the cloaca, which the scientists now can extend back to the Mesozoic dinosaur ancestors.

Robert Nicholls said: “As a palaeoartist, it has been absolutely amazing to have an opportunity to reconstruct one of the last remaining features we didn’t know anything about in dinosaurs.

“Knowing that at least some dinosaurs were signalling to each other gives palaeoartists exciting freedom to speculate on a whole variety of now plausible interactions during dinosaur courtship. It is a game changer!”

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Materials provided by University of Bristol. Note: Content may be edited for style and length.

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