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CRISPR-Cas9 base editors comprise RNA-guided Cas proteins fused to an enzyme that can deaminate a DNA nucleoside. No natural enzyme deaminates adenine in DNA, and so a breakthrough came when a natural transfer RNA deaminase was fused to Cas9 and evolved to give an adenine base editor (ABE) that works on DNA. Further evolution provided the enzyme ABE8e, which catalyzes deamination more than 1000 times faster than early ABEs. Lapinaite et al. now present a 3.2-angstrom resolution structure of ABE8e bound to DNA in which the target adenine is replaced with an analog designed to trap the catalytic conformation. The structure, together with kinetic data comparing ABE8e to earlier ABEs, explains how ABE8e edits DNA bases and could inform future base-editor design.

Science, this issue p. 566

CRISPR-Cas–guided base editors convert A•T to G•C, or C•G to T•A, in cellular DNA for precision genome editing. To understand the molecular basis for DNA adenosine deamination by adenine base editors (ABEs), we determined a 3.2-angstrom resolution cryo–electron microscopy structure of ABE8e in a substrate-bound state in which the deaminase domain engages DNA exposed within the CRISPR-Cas9 R-loop complex. Kinetic and structural data suggest that ABE8e catalyzes DNA deamination up to ~1100-fold faster than earlier ABEs because of mutations that stabilize DNA substrates in a constrained, transfer RNA–like conformation. Furthermore, ABE8e’s accelerated DNA deamination suggests a previously unobserved transient DNA melting that may occur during double-stranded DNA surveillance by CRISPR-Cas9. These results explain ABE8e-mediated base-editing outcomes and inform the future design of base editors.

Crop yields for apples, cherries and blueberries across the United States are being reduced by a lack of pollinators, according to Rutgers-led research, the most comprehensive study of its kind to date.

Most of the world’s crops depend on honeybees and wild bees for pollination, so declines in both managed and wild bee populations raise concerns about food security, notes the study in the journal Proceedings of the Royal Society B: Biological Sciences.

“We found that many crops are pollination-limited, meaning crop production would be higher if crop flowers received more pollination. We also found that honey bees and wild bees provided similar amounts of pollination overall,” said senior author Rachael Winfree, a professor in the Department of Ecology, Evolution, and Natural Resources in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. “Managing habitat for native bee species and/or stocking more honey bees would boost pollination levels and could increase crop production.”

Using the Subaru Telescope, astronomers have identified two new dust-reddened (red) quasars at high redshifts. The finding, detailed in a paper published July 16 on the arXiv pre-print server, could improve the understanding of these rare but interesting objects.

Quasars, or quasi-stellar objects (QSOs), are extremely luminous active galactic nuclei (AGN) containing supermassive central black holes with accretion disks. Their redshifts are measured from the strong spectral lines that dominate their visible and ultraviolet spectra. Some QSOs are dust-reddened, hence dubbed red quasars. These objects have non-negligible amount of dust extinction, but are not completely obscured.

Astronomers are especially interested in finding new high–redshift quasars (at redshift higher than 5.0) as they are the most luminous and most distant compact objects in the observable universe. Spectra of such QSOs can be used to estimate the mass of supermassive black holes that constrain the evolution and formation models of quasars. Therefore, high-redshift quasars could serve as a powerful tool to probe the early universe.

Ecuador has sounded the alarm after its navy discovered a huge fishing fleet of mostly Chinese-flagged vessels some 200 miles from the Galápagos Islands, the archipelago which inspired Charles Darwin’s theory of evolution.

About 260 ships are currently in international waters just outside a 188-mile wide exclusive economic zone around the island, but their presence has already raised the prospect of serious damage to the delicate marine ecosystem, said a former environment minister, Yolanda Kakabadse.

“This fleet’s size and aggressiveness against marine species is a big threat to the balance of species in the Galápagos,” she told the Guardian.

In nature, organisms often support each other in order to gain an advantage. However, this kind of cooperation contradicts the theory of evolution proposed by Charles Darwin: Why would organisms invest valuable resources to help others? Instead, they should rather use them for themselves, in order to win the evolutionary competition with other species. A new study led by Prof. Dr. Christian Kost from the Department of Ecology at Osnabrueck University has now solved this puzzle. The results of the study were published in the scientific journal Current Biology. The research project was performed in collaboration with the Max Planck Institute for Chemical Ecology in Jena.

Interactions between two or more organisms, in which all partners involved gain an advantage, are ubiquitous in nature and have played a key role in the evolution of life on Earth. For example, root bacteria fix nitrogen from the atmosphere, thus making it available to plants. In return, the plant supplies its root bacteria with nutritious sugars. However, it is nevertheless costly for both interaction partners to support each other. For example, the provision of sugar requires energy, which is then not available to the plant anymore. From this results the risk of cheating interaction partners that consume the sugar without providing nitrogen in return.

The research team led by Prof. Dr. Christian Kost used bacteria as a model system to study the evolution of mutual cooperation. At the beginning of the experiment, two bacterial strains could only grow when they provided each other with essential amino acids. Over the course of several generations, however, the initial exchange of metabolic byproducts developed into a real cooperation: both partners increased the production of the exchanged amino acids in order to benefit their respective partner. Even though the increased amino acid production enhanced growth when both partners were present, it was extremely costly when individual bacterial strains had to grow without their partner.

🔬 The search for ancient life 🔴 Planetary evolution 👨‍🚀 Preparing for future human exploration.

There are so many reasons to study the Red Planet.

These non-random epigenetic changes imply that evolution has a “mind.” Creatures appear to have complex mechanisms to make epigenetic changes that allow them to adapt to future environmental challenges. But where did this forward-thinking design come from? Evolution is mindless; it cannot see the future. So how could it evolve mechanisms to prepare for the future?

But God does! God is omniscient (all-knowing), and He foreknew Adam and Eve would sin. He would judge that sin (Gen. 3) and the world would be cursed (Rom. 8:22). God knew that organisms would need the ability to adapt in a world that was no longer “very good.” God likely designed organisms with epigenetic mechanisms to allow them to change easily and quickly in relation to their environment. These types of changes are much more valuable than random mutation and natural selection because they can produce immediate benefits for offspring without harming the basic information in the actual sequence of DNA.

Although we often hear that “nothing in biology makes sense except in the light of evolution,” it should be said that “nothing in biology makes sense without the Creator God.” Epi genetics is an exciting field of science that displays the intelligence and providence of God to help organisms adapt and survive in a fallen world.

Various diseases of the digestive tract, for example severe intestinal inflammation in humans, are closely linked to disturbances in the natural mobility of the intestine. What role the microbiome—i.e. the natural microbial community colonizing the digestive tract—plays in these rhythmic contractions of the intestine, also known as peristalsis, is currently the subject of intensive research. It is particularly unclear how the contractions are controlled and how the cells of the nervous system, that act as pacemakers, function together with the microorganisms.

A research team from the Cell and Developmental Biology group at Kiel University has now succeeded in demonstrating for the first time, using the freshwater polyp Hydra as an example, that phylogenetically old neurons and bacteria actually communicate directly with each other. Surprisingly, they discovered that the nerve cells are able to cross-talk with the microorganisms via immune receptors, i.e., to some extent with the mechanisms of the immune system.

On this basis, the scientists of the Collaborative Research Center (CRC) 1182 “Origin and Function of Metaorganisms” formulated the hypothesis that the nervous system has not only taken over sensory and motor functions from the onset of evolution, but is also responsible for communication with the microbes. The Kiel researchers around Professor Thomas Bosch published their results together with international colleagues today in the journal Proceedings of the National Academy of Sciences (PNAS).

Supergenes Play a Larger Role in Evolution Than Previously Thought

Massive blocks of genes—inherited together ‘plug and play’ style—may play a larger role in evolutionary adaption than previously thought, according to new research in Nature.

Biologists identified 37 of these so-called ‘supergenes’ in wild sunflower populations, and found they govern the modular transfer of a large range of traits important for adaptation to local habitats. Those include seed size, timing of flowering, as well as the ability to withstand environmental stresses such as drought or limited nutrient availability, among many others.