The week’s most astounding developments from the neobiological frontier.

August 25, 2022

Therapeutic plasma exchange makes old blood young

One theory of human longevity posits that aging is driven by something known as systemic molecular excess—an increase with age of inflammatory proteins and other effectors in the blood, which leads to chronic inflammation. This idea informs an experimental approach known as therapeutic plasma exchange (see our first person account here) which seeks to counter chronic “inflammaging” by circulating someone’s blood through a machine that removes the plasma and replaces it with saline and albumin. A new paper by the Conboys at the University of California, Berkeley, shows the effect of therapeutic plasma exchange on blood composition in a tiny human study. The researchers compared blood taken from eight older people before and after rounds of plasma exchange with blood taken from control groups of older and younger people. Proteomic analysis showed that plasma exchange shifted the blood of the eight older people undergoing plasma exchange toward the younger controls with each round of therapy. What’s more, the changes “are not limited to a reduction of inflammaging but encompass diminished circulatory protein markers of neurodegeneration and cancer, as well as reduced senescence, lower DNA damage, and improved myeloid/lymphoid homeostasis,” according to the researchers. GeroScience

A baby step toward chromosome engineering

Despite the many genetic engineering challenges we’ve bested in our CRISPR-Cas-charged world, there is one hurdle synthetic biology has never surmounted: the “wholesale” alteration of an animal’s DNA by directly manipulating its entire chromosomes. While chromosome engineering has been done successfully in yeast, nobody has ever achieved it in higher organisms like mammals. Setting aside the obvious safety and ethical questions for the moment, chromosome engineering represents a massive technological leap. It could allow us to shove vast numbers of exotic genes into creatures at once—and possibly even enable the wholesale creation of a new animal species in the laboratory. Now researchers at the Chinese Academy of Sciences in Beijing have taken a baby step toward chromosome engineering by creating new chromosomal combinations (known as “karyotypes”) in laboratory mice. They fused together two medium-sized mouse chromosomes, the mice lived, and they passed on the combined chromosome to their offspring. Science

An adult mouse with a novel karyotype created by fusing chromosomes 4 (green) and 5 (red), shown in the microscope image. Photo by Qiang Wang, image by Li-Bin Wang

Your brain has a built-in network for recognizing food

When you recognize a friendly face in a crowd, you can thank a set of anatomically distinct regions in the brain called the ventral visual pathway, which processes visual information by connecting cues we see to things like memories, emotions, and value judgements stored in other parts of the brain. For decades, neuroscientists have known the ventral visual pathway is strongly attuned to certain types of visual cues like bodies, scenes, and written text. Now a team of researchers at MIT has found an unexpected addition to that list: food. Analyzing the fMRI brain scans of eight people looking at thousands of images, the researchers showed that the brain’s ventral visual pathway consistently responds in a “highly selective fashion” to images of food—though it’s not clear if the response is driven by immediate hunger, a higher appreciation of taste, or a basic lizard brain longing for nutrition. Current Biology

How psychedelic trips compare to near-death experiences

Researchers at the Johns Hopkins University School of Medicine in Baltimore have surveyed more than 2,000 people who experimented with LSD, psilocybin, ayahuasca, or DMT and compared their responses to 933 people who had non-drug related near-death experiences. The results were fascinating. “The groups were remarkably similar in the reported changes in death attitudes attributed to the experience, including a reduced fear of death and high ratings of positive persisting effects and personal meaning, spiritual significance, and psychological insight,” the researchers write. PLOS ONE

New method for speeding crop selection

Long before genetically modified plants were even a thing, there was the green revolution—a 1950s lesson in cross-breeding success that won the Nobel prize for Norman Borlaug and saved a billion people around the world from starvation. Traditional cross-bred crops like Borlaug’s hearty dwarf wheat now share supermarket shelves with crops developed through random mutagenesis—and in some countries with fruits and vegetables designed with more sophisticated, if controversial genetic modifications. All approaches to developing new crop varietals rely on one thing, however: You have to be able to identify the seedlings that have the exact traits you desire. Now scientists at Carlsberg Research Laboratory in Copenhagen, Denmark, have designed a way to speed the selection of traits like drought tolerance, flood tolerance, disease resistance, and nutrient efficiency by using a tool named FIND-IT. They used the tool to screen 500,000 barley plants and isolated numerous strains with desirable traits. Science Advances

REM sleep: You really are looking around in your dreams

Why do humans and other animals undergo rapid eye movement (REM) while they sleep? Many scientists have assumed it’s because REM sleep is closely associated with dreaming and our eye movements correspond to us looking around in our dreams. Up to now unproven, this hypothesis was strongly supported this week by experiments at the University of California, San Francisco that monitored the brains of sleeping mice. The UCSF researchers found that the direction and amplitude of eye movements during REM sleep correlated with activity in a system of neurons corresponding to the animal’s head direction when awake. Similarities between mammalian brains suggest the same correlations exist in sleeping people, and it opens the door to new therapies designed to interfere with or delete unwanted memories by modulating eye movements during REM sleep. Inception, anyone? Science

Don’t ask for help when it’s daylight saving time

Across the San Francisco Bay, scientists at the University of California, Berkeley, also looked at sleep this week—and how not having enough of it impacts human altruism. They found that a single night of sleep loss deactivates key brain networks linked to pro-sociality and causes people to undergo a significant decrease in the desire to help others. Several nights of sleep loss corresponded to people wanting to help others less during interactions the next day. They also analyzed more than three million charitable donations given in the United States between 2001–2016 and showed that on the national level, the sleep loss due to daylight saving time was associated with a 10 percent decrease in donation amounts compared to previous or later weeks. PLOS Biology