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Category: evolution – Page 82

Astronomers at the Center for Astrophysics | Harvard & Smithsonian (CfA) have unveiled a first-of-its-kind map that could help answer decades-old questions about the origins of stars and the influences of magnetic fields in the cosmos.

The map reveals the likely structure of the Local Bubble—a giant, 1,000-light-year-wide hollow in space surrounding our Sun. Like a hunk of Swiss cheese, our galaxy is full of these so-called superbubbles. The explosive supernova deaths of massive stars blow up these bubbles, and in the process, concentrate gas and dust—the fuel for making —on the bubbles’ outer surfaces. These thick surfaces accordingly serve as rich sites for subsequent star and planet formation.

Scientists’ overall understanding of superbubbles, however, remains incomplete. With the new 3D magnetic field map, researchers now have novel information that could better explain the evolution of superbubbles, their effects on star formation and on galaxies writ large.

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Sixty-six million years ago, the age of the dinosaurs came to a dramatic close as a huge asteroid impact accelerated them on a path towards extinction. Not all of them died out, however; those that survived went on to become today’s birds.

Scientists are still trying to carefully map out the anatomical changes that occurred between dinosaurs and birds during this time, and there’s arguably no better way to do this than to engage in a little “reverse evolution.” With this in mind, a team of researchers has grown “dinosaur legs” in chicken embryos, as revealed in their study in the journal Evolution.

Remarkably, previous research manipulating chickens into “becoming” dinosaurs has already taken place. Back in 2015, a study showcased that chickens that had been tweaked during embryonic development could grow a dinosaur-like snout. A year earlier, a more low-tech study demonstrated how a few strategically-placed weights could make a chicken walk along like a Tyrannosaurus rex.

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A new study by researchers at the University of Nottingham has shed light on the complexity of our ancient ancestors, solving an important piece of the animal evolution puzzle.

A new study by researchers at the University of Nottingham has revealed that our ancient ancestors were more complex than originally thought, solving an important piece of the animal evolution puzzle.

In the distant past, animals underwent a significant evolution by developing bilateral symmetry and two gut openings. This allowed them to move faster through the early seas, find food and extract nutrients more efficiently, and protect themselves from predators. The success of this trait can be seen in the diverse range of animals that still possess bilateral symmetry and two gut openings today, including humans, starfish, sea cucumbers, elephants, crickets, and snails. Additionally, a group of simple marine worms called Xenacoelomorphs also exhibit this trait, despite lacking the complex features of other animals.

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An international research group has for the first time reconstructed ancestors dating back 2.6 billion years of the well-known CRISPR-Cas system, and studied their evolution over time. The results suggest that the revitalized systems not only work, but are more versatile than current versions and could have revolutionary applications. Nature Microbiology has published the results of this research, which, in the opinion of the research team, “opens up new avenues for gene editing.”

The project, led by Ikerbasque research professor Rául Pérez-Jiménez of CIC nanoGUNE, involves teams from the Spanish National Research Council, the University of Alicante, the Rare Diseases Networking Biomedical Research Center (CIBERER), the Ramón y Cajal Hospital-IRYCIS and other national and international institutions.

The acronym CRISPR refers to the repeated sequences present in the DNA of bacteria and archaea (prokaryotic organisms). Among the repeats, these microorganisms harbor fragments of genetic material from viruses that infected their ancestors; that enables them to recognize a repeat infection and defend themselves by cutting the invaders’ DNA using Cas proteins associated with these repeats. It is a mechanism (CRISPR-Cas system) of antiviral defense. This ability to recognize DNA sequences is the basis of their usefulness, and they act as if they were molecular scissors. Nowadays CRISPR-Cas technology enables pieces of genetic material to be cut and pasted into any cell, so that it can be used to edit DNA.

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“This research signifies an extraordinary advance in knowledge about the origin and evolution of CRISPR-Cas systems.”

An international research team reconstructed the CRISPR-Cas system for the first time, dating back to 26 billion years ago. Their findings imply that the revived systems are functional and more adaptable than the previous iterations.

Led by teams from the Spanish National Research Council, the University of Alicante, the Rare Diseases Networking Biomedical Research Center (CIBERER), the Ramón y Cajal Hospital-IRYCIS, and other national and international institutions are working with Ikerbasque research professor Rául Pérez-Jiménez of CIC nanoGUNE.

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Clustered regularly interspaced short palindromic repeats (CRISPR)-associated Cas9 protein is an effector that plays a major role in a prokaryotic adaptive immune system, by which invading DNA can be targeted and cut for inactivation. The Cas9 endonuclease is directed to target sites by a guide RNA (gRNA) where Cas9 can recognize specific sequences (PAMs) in foreign DNA, which then serve as an anchoring point for cleavage of the adjacent RNA-matching DNA region. Although the CRISPR-Cas9 system has been widely studied and repurposed for diverse applications (notably, genome editing), its origin and evolution remain to be elucidated. Here, we investigate the evolution of Cas9 from resurrected ancient nucleases (anCas) in extinct firmicutes species as old as 2,600 myr to the current day. Surprisingly, we demonstrate that these ancient forms were much more flexible in their PAM and gRNA scaffold requirements compared to modern day Cas9 enzymes. In addition, anCas portrays a gradual paleoenzymatic adaptation from nickase to double-strand break activity, suggesting a mechanism by which ancient CRISPR systems could propagate when harboring Cas enzymes with minimal PAMs. The oldest anCas also exhibit high levels of activity with ssDNA and ssRNA targets, resembling Cas nucleases in related system types. Finally, we illustrate editing activity of the anCas enzymes in human cells. The prediction and characterization of anCas proteins uncovers an unexpected evolutionary trajectory leading to ancient enzymes with extraordinary properties.

R. P-J., B. A-L. are co-inventors on patent application filed by CIC nanoGUNE and licenced to Integra Therapeutics S.L. relating to work in this article. A. S-M. and M.G. are co-founders of Integra Therapeutics S.L. B.P.K is an inventor on patents and/or patent applications filed by Mass General Brigham that describe genome engineering technologies. B.P.K. is a consultant for Avectas Inc., EcoR1 capital, and ElevateBio, and is an advisor to Acrigen Biosciences and Life Edit Therapeutics.

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The College of Psychiatrists of Ireland Evolution and Psychiatry Special Interest Group welcomed Dr Randolph M Nesse to present a talk titled “Why hasn’t natural selection eliminated mental disorders: Knowing the five reasons improves clinical care as well as research” during their meeting on Friday, 4 February 2022.

The Special Interest Group is open to all College members and Psychiatry trainees.

Keep up to date on all College events on the CPsychI website: https://www.irishpsychiatry.ie/all-events/

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