Frequent fliers, take note. Scientists have figured out how cells quickly pack long chromosomes into compact, organized bundles — a key step before cells divide. The new finding unifies two competing ideas about the process: whether it involves winding chromosomes into a spiral staircase or into a set of loops. It turns out cells use two different ring-shaped proteins called condensins to do both actions, imaging and computer simulations reveal.

Normally, chromosomes sit unspooled in a cell’s nucleus. But when a cell prepares to undergo mitosis — a type of cell division — those strings of DNA must condense into easy-to-transfer cylinders. It’s a formidable task: A cell must cram about two meters of DNA into microscopic packages without tangling the genetic material like a string of holiday lights.
Condensin II shapes a chromosome into large loops and then forms a helical scaffold for the loops to wind around. Condensin I subdivides large loops into smaller nested loops that allow for more space-efficient packing.

Together, the two proteins deftly stuff the chromosome into a densely packed cylinder, scientists report online January 18 in Science. Most of that condensing process happens in about 15 minutes, says study coauthor Job Dekker, a Howard Hughes Medical Institute investigator at the University of Massachusetts Medical School in Worcester.

Not all fundamental forces are created equal. An alternate universe that lacks the weak nuclear force — one of the four fundamental forces that govern all matter in our universe — could still form galaxies, stars, planets and perhaps life, according to calculations published online January 18 at arXiv.org.

Scientists have long thought that our universe wouldn’t exist, or at least wouldn’t support life, without certain physical laws. For instance, if gravity were much stronger than it is, most matter would collapse into black holes; if it were weaker, the universe wouldn’t form structures such as galaxies or planets. The strong nuclear force holds atomic nuclei together, and the electromagnetic force carries light across the universe.
“Those three forces, gravity, strong and electromagnetic, are part of the deal,” says theoretical physicist Fred Adams of the University of Michigan in Ann Arbor. But the weak nuclear force — responsible for making neutrons decay into protons, electrons and neutrinos — might not be so essential (SN: 4/29/17, p. 22). “That’s the only one you can get rid of entirely without messing everything up,” he says.

A previous study had argued that a universe lacking the weak force could exist. Some physicists think our universe is just one in an infinite multiverse, where many different cosmoses exist side-by-side, possibly governed by different physical rules. We live in this one simply because we couldn’t live anywhere else (SN Online: 10/10/14), some scientists say.

“People talk about universes like they’re very fine-tuned; if you changed things just a little bit, life would die,” Adams says. But “the universe and stars have a lot more pathways to success.”

In the new research, he and his colleagues simulated how matter was created in the Big Bang and then condensed into stars, but without the effects of the weak nuclear force. In our universe, one consequence of neutron decay is that most of the universe is made of hydrogen, which consists of a single proton and electron. Stars, in their hot cores, fuse protons into helium and heavier elements and then scatter them into space, helping to create everything from planets to physicists. But with no weak force, a universe would be filled with neutrons that didn’t decay — a dead end for building heavier elements.
The only way such a universe could create complex matter would be to have started out with fewer neutrons and more free protons than our universe did. That way, neutrons and protons could link up and make deuterium, also called heavy hydrogen. So Adams and his colleagues tweaked the simulated universe’s initial neutron and proton content, too.

Stars fueled with deuterium would still shine, the simulations showed, but the objects would look different. Burning deuterium is more efficient than burning hydrogen, so these stars would be a little hotter, larger and redder than our stars. But the stars could still create all the elements of the periodic table up to iron, and stellar winds could carry those elements out into space.

Any planets that formed would have water made with deuterium instead of hydrogen, which is toxic to life in our universe. “But if life had to evolve with deuterated water … it might be OK,” Adams says.

Adams and his colleagues are some of the first to explore the consequences of a “weakless” universe seriously by tweaking the numbers, says Martin Rees of the University of Cambridge, who was not involved in either study.

The paper does not help figure out if the multiverse is real, though. “We hope that eventually we’ll know,” Rees says, but “I’m not holding my breath.”

A pair of dark loners wander a distant cluster of galaxies. The two small gas clouds have been roaming the Virgo cluster, some 55 million light-years away, for at least a billion years. Such small, isolated clouds of gas shouldn’t be able to form stars on their own — and yet they are doing just that.

Astronomer Michele Bellazzini of the Italian National Institute for Astrophysics in Bologna and his colleagues found the small, dim clouds in 2014 in the SECCO survey, which looks for the building blocks of galaxies. The two are moving at the same speed and have the same chemical composition, so the researchers think they have the same origin story.
Together, the clouds, called SECCO 1, have just 160,000 solar masses’ worth of stars, but 20 million solar masses of hydrogen gas—a lot more hydrogen than found in other small starry bodies. Dwarf galaxies typically have 10 times more hydrogen than stars; SECCO 1 has more than 100 times more. And the duo is abnormally isolated: the nearest potential parent galaxies are about 815,000 light-years away. “This is a novelty,” Bellazzini says.

Simulations suggest SECCO 1 was stripped from a trio of interacting dwarf galaxies, the researchers report online at arXiv.org on February 16 . Weirdly, it started forming stars long after it wandered away, which researchers didn’t think was possible. Its latest bout of star formation started only 4 million years ago. How did the tiny clouds compress enough gas to form stars?

Bellazzini thinks the key could be the clouds’ home within the Virgo cluster. Hot gas there could surround the clouds and compress them enough to make them light up.

Editor’s note: This story was updated March 7, 2018, to correct the photo credit and mention where the simulations were reported. On March 9, 2018, the distance to nearest potential parent galaxies was corrected.

At a small eatery in Seville, Spain, Alan Jasanoff had his first experience with brains — wrapped in eggs and served with potatoes. At the time, he was more interested in finding a good, affordable meal than contemplating the sheer awesomeness of the organ he was eating. Years later, Jasanoff began studying the brain as part of his training as a neuroscientist, and he went on, like so many others, to revere it. It is said, after all, to be the root of our soul and consciousness. But today, Jasanoff has yet another view: He has come to see our awe of the organ as a seriously flawed way of thinking, and even a danger to society.
In The Biological Mind, Jasanoff, now a neuroscientist at MIT, refers to the romanticized view of the brain — its separateness and superiority to the body and its depiction as almost supernatural — as the “cerebral mystique.” Such an attitude has been fueled, in part, by images that depict the brain without any connection to the body or by analogies that compare the brain to a computer. Admittedly, the brain does have tremendous computing power. But Jasanoff’s goal is to show that the brain doesn’t work as a distinct, mystical entity, but as a ball of flesh awash with fluids and innately in tune with the rest of the body and the environment. “Self” doesn’t just come from the brain, he explains, but also from the interactions of chemicals from our bodies with everything else around us.

To make his case, Jasanoff offers an extensive yet entertaining review of the schools of thought and representations of the brain in the media that led to the rise of the cerebral mystique, especially during the last few decades. He then tears down those ideas using contrary examples from recent research, along with engaging anecdotes. For instance, his clear, lively writing reveals how our emotions, such as the fight-or-flight response and the suite of thoughts and actions associated with stress, provide strong evidence for a brain-body connection. Exercise’s effect on the brain also supports this notion. Even creativity isn’t sacred, often stemming from repeated interactions with those around us.

Jasanoff is critical of how the cerebral mystique reduces problems of human behavior, such as drug addiction or eating disorders, to problems of the brain. Such problems are no longer viewed as “moral failings” but as a result of “broken brains.” This shifting view, its advocates argue, reduces the stigma associated with psychiatric disorders. But it also leads to other problems, Jasanoff notes: Society views broken brains as harder to fix than moral flaws, making life even more challenging for individuals already struggling with mental illness. People could benefit from a more comprehensive view of the brain, one that includes how biology, environment and culture shape behavior.

When mental processes are seen as transcending the body, society perceives people as “more independent and self-motivated than they truly are,” and that minimizes “the connections that bind us to each other and to the environment around us,” Jasanoff writes. As a result, he argues, we’re living in an age of self-absorption and self-centeredness, driven in part by our fascination with the brain.
In reality, the brain isn’t a miraculous machine, but instead a prism refracting countless internal and external influences. A few more specifics on how this prism works — details of what is going on at the cellular or molecular level, for instance — might have helped support Jasanoff’s arguments.

But he does leave readers with a thought-provoking idea: “You are not only your brain.” Grapple with that, he contends, and we could move toward communities that are much more socially minded and accepting of our interconnectedness.

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