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Category: genetics – Page 460

UNSW team taps light-activated liposomes for safer CRISPR delivery

Researchers in Australia are shining a spotlight on a safer delivery method for targeted CRISPR gene therapies—and they’re using literal illumination to pull it off.

Scientists and biomedical engineers from the University of New South Wales Sydney say they’ve developed a light-sensitive liposome that can ferry CRISPR molecules to specific sites in the body. When hit with LED light, the liposomes unleash their CRISPR payloads to hunt down faulty genes.

The CRISPR-Cas9 gene-editing tool consists of a guide RNA that homes in on a target in the DNA, and the Cas9 enzyme, which cuts the DNA much like a pair of molecular scissors. A slate of companies is exploring the technology to treat cancer and even blindness, but the therapy is traditionally delivered using viruses, which can themselves spur unwanted immune responses and other side effects.

Getting it just right: The Goldilocks model of cancer

Senescence in cancer cells

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Sometimes, too much of a good thing can turn out to be bad. This is certainly the case for the excessive cell growth found in cancer. But when cancers try to grow too fast, this excessive speed can cause a type of cellular aging that actually results in arrested growth. Scientists at Duke-NUS Medical School have now discovered that a well-known signaling pathway helps cancers grow by blocking the pro-growth signals from a second major cancer pathway.

Inhibiting Wnt signaling with ETC-159 reactivates the hyperactive RAS-MAPK , causing cells to led undergo senescence. Many cancers are driven by activating mutations in the RAS-MAPK signaling pathway which triggers a cascade of proteins that directs cells to grow, divide and migrate. Mutations in proteins involved in this cascade can turn on genes that make this process go into overdrive, causing cells to grow out of control and aggressively invade other parts of the body. However, too much RAS-MAPK signaling causes cancer cells to prematurely age, and eventually stop growing—a process called cellular senescence.

Publishing in Cancer Research, the Duke-NUS research team found that another important and well-known biochemical pathway, the Wnt (pronounced “wint”) signaling pathway, allows some cancers to grow by dampening RAS-MAPK signaling.

Scientists sequence genome of bowhead whale—longest-lived mammal

Scientists at the University of Liverpool have sequenced the genome of the bowhead whale, estimated to live for more than 200 years with low incidence of disease.

Published in the journal Cell Reports, the research could offer new insight into how animals and humans could achieve a long and healthy life.

Scientists compared the genome with those from other shorter-lived mammals to discover unique to the bowhead whale.

Synthetic biology crucial to human missions to Mars

In Project Apollo, life support was based on carrying pretty much everything that astronauts needed from launch to splashdown. That meant all of the food, air, and fuel. Fuel in particular took up most of the mass that was launched. The enormous three-stage Saturn-V rocket was basically a gigantic container for fuel, and even the Apollo spacecraft that the Saturn carried into space was mostly fuel, because fuel was needed also to return from the Moon. If NASA’s new Orion spacecraft takes astronauts back to the Moon, they’ll also use massive amounts of fuel going back and forth; and the same is true if they journey to a near-Earth asteroid. However, once a lunar base is set up, astronauts will be able use microorganisms carried from Earth to process lunar rock into fuel, along with oxygen. The latter is needed not just for breathing, but also in rocket engines where it mixes with the fuel.

Currently, there are microorganisms available naturally that draw energy from rock and in the process release chemical products that can be used as fuel. However, as with agricultural plants like corn and soy, modifying such organisms can potentially make a biologically-based lunar rock processing much more efficient. Synthetic biology refers to engineering organisms to pump out specific products under specific conditions. For spaceflight applications, organisms can be engineered specifically to live on the Moon, or for that matter on an asteroid, or on Mars, and to synthesize the consumables that humans will need in those environments.

In the case of Mars, a major resource that can be processed by synthetic biology is the atmosphere. While the Martian air is extremely thin, it can be concentrated in a biological reactor. The principal component of the Martian air is carbon dioxide, which can be turned into oxygen, food, and rocket fuel by a variety of organisms that are native to Earth. As with the Moon rocks, however, genetic techniques can make targeted changes to organisms’ capabilities to allow them to do more than simply survive on Mars. They could be made to thrive there.

Lurking in Genomic Shadows: How Giant Viruses Fuel the Genetic Evolution of Organisms

Viruses are tiny invaders that cause a wide range of diseases, from rabies to tomato spotted wilt virus and, most recently, COVID-19 in humans. But viruses can do more than elicit sickness — and not all viruses are tiny.

Large viruses, especially those in the nucleo-cytoplasmic large DNA virus family, can integrate their genome into that of their host — dramatically changing the genetic makeup of that organism. This family of DNA viruses, otherwise known as “giant” viruses, has been known within scientific circles for quite some time, but the extent to which they affect eukaryotic organisms has been shrouded in mystery — until now.

“Viruses play a central role in the evolution of life on Earth. One way that they shape the evolution of cellular life is through a process called endogenization, where they introduce new genomic material into their hosts. When a giant virus endogenizes into the genome of a host algae, it creates an enormous amount of raw material for evolution to work with,” said Frank Aylward, an assistant professor in the Department of Biological Sciences in the Virginia Tech College of Science and an affiliate of the Global Change Center housed in the Fralin Life Sciences Institute.

Genetic Adam and Eve did not live too far apart in time

Circa 2013

The Book of Genesis puts Adam and Eve together in the Garden of Eden, but geneticists’ version of the duo — the ancestors to whom the Y chromosomes and mitochondrial DNA of today’s humans can be traced — were thought to have lived tens of thousands of years apart. Now, two major studies of modern humans’ Y chromosomes suggest that ‘Y-chromosome Adam’ and ‘mitochondrial Eve’ may have lived around the same time after all1, 2.

When the overall population size does not change (as is likely to have happened for long periods of human history), men have, on average, just one son. In this case, evolutionary theory predicts that for any given man there is a high probability that his paternal line will eventually come to an end. All of his male descendants will then have inherited Y chromosomes from other men. In fact, it is highly probable that at some point in the past, all men except one possessed Y chromosomes that by now are extinct. All men living now, then, would have a Y chromosome descended from that one man — identified as Y-chromosome Adam. (The biblical reference is a bit of a misnomer because this Adam was by no means the only man alive at his time.)

Similarly, the theory predicts that all mitochondrial genomes today should be traceable to a single woman, a ‘mitochondrial Eve’. Whereas the Y chromosome is passed from father to son, mitochondrial DNA (mtDNA) is passed from mother to daughter and son.

Researchers identify the genetic program that allows us to see in 3D

A group of researchers from the Institute of Neurosciences UMH-CSIC, in Alicante, led by Dr. Eloísa Herrera, has discovered a genetic program essential for the formation of bilateral circuits, such as the one that makes possible 3D vision or the one enabling motor coordination. The finding, carried out in mice, is published today in Science Advances.

This new study not only clarifies how images are transmitted from the retina to the brain in order to see in 3D, but also helps us to understand how laterality is established in other neuronal circuits, such as the one that allows us to coordinate movements at both sides of the body, Dr. Herrera explains.

The work also reveals the important role of a protein known as Zic2 in the regulation of a signaling called Wnt, which is fundamental for the correct development of the embryo and is highly conserved among species, from fruit flies to humans, including mice, in which this study has been carried out.

Newly-Discovered Deep Sea ‘Mushroom’ Could Re-Write Tree of Life

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Most newly-discovered species are easy to classify. They have features that are very consistent with well-known organisms and they fit neatly into one category or another. Every so often, one comes along that leaves scientists wondering, “What the hell is this thing?” Case in point: Dendrogramma. This new genus represents two species of deep-sea animals that resemble mushrooms but don’t really fit in with any other known animals. As a result, this organism could bring fairly large changes to the phylogenetic tree. The research was conducted by a team of researchers from the University of Copenhagen and the paper was published in PLOS ONE.

The 18 specimens were caught during an expedition in the Bass Strait, between Australia and Tasmania back in 1986. Two samples were dredged up from depths of 400 and 1000 meters. The samples had been fixed and preserved, rendering them unable to undergo genetic analysis. However, the preservation process was not done particularly well, causing them to become bleached and shrunken. They turned brittle over time.

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