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'One among millions': DNA is not the only genetic molecule
A recent computer analysis found that millions of possible chemical compounds could be used to store genetic information. This begs the question — why DNA?
- The central dogma of biology states that genetic information flows from DNA to RNA to proteins, but new research suggests that this may not be the only way for life to work.
- A sophisticated computer analysis revealed that millions of other molecules could be used to function in place of the two nucleic acids, DNA and RNA.
- The results have important implications for developing new drugs, the origins of life on Earth, and its possible presence in the rest of the universe.
Simply put, the so-called central dogma of biology asserts that genetic information flows from DNA to RNA to proteins, and once that information is passed to a protein, it cannot be returned as DNA or RNA again. It's dubbed the central dogma because it seems to be universal amongst all living organisms. There are some exceptions to the linear flow described in the popular version of the central dogma — information can be passed back and forth between RNA and DNA or between DNA and DNA or RNA and RNA, but the central players remain the same: DNA, RNA, and proteins.
But what if this didn't have to be the case? Could genetic information be stored in media other than the two nucleic acids of DNA and RNA? New research published in the Journal of Chemical Information and Modeling suggests that there might not be just a handful of alternative molecules for storing genetic information, but millions.
Millions of useful targets
The central dogma of biology asserts that the genetic information is transcribed from DNA to RNA, which then translates that information into useful products like proteins. This new research, however, suggests that DNA and RNA are just two options out of millions of others.
Analogues to nucleic acids exist, many of which serve as the foundation for important drugs for treating viruses like HIV and hepatitis as well as for treating cancers, but until recently, no one was sure of how many unknown nucleic acid analogues could be out there.
"There are two kinds of nucleic acids in biology," said co-author Jim Cleaves, "and maybe 20 or 30 effective nucleic acid-binding nucleic acid analogues. We wanted to know if there is one more to be found or even a million more. The answer is, there seem to be many more than was expected."
Cleaves and colleagues decided to conduct a chemical space analysis — in essence, a sophisticated computer technique that generates all possible molecules that adhere to a set of defined criteria. In this case, the criteria were to find compounds that could serve as nucleic acid analogues and as a means of storing genetic information.
"We were surprised by the outcome of this computation," said co-author Markus Meringer. "It would be very difficult to estimate a priori that there are more than a million nucleic acid–like scaffolds. Now we know, and we can start looking into testing some of these in the lab."
Though no specific analogues were targeted in this paper, it does present a long list of candidates to be explored for use as drugs for serious diseases like HIV or cancer. A more intriguing possibility suggested by the research is that life itself may have taken its very first steps using one of these alternative compounds.
Many scientists believe that before DNA became the dominant means of storing genetic information, life used RNA to code genetic data and pass it down to offspring. In part, this is because RNA can directly produce proteins, which DNA can't do on its own, and because it's a simpler structure than DNA. Over time, life likely started to opt for using DNA for storage due to its greater stability and to rely on RNA as a kind of middleman for producing proteins. But RNA on its own is still a very complicated compound and is fairly unstable; in all likelihood, something simpler came before RNA, possibly using some of the nucleic acid analogues identified in this study.
A galaxy of nucleic acid analogues
Not only does this shed light on how life may have started on Earth, but it also has implications for alien life as well. Co-author Jay Goodwin said, "It is truly exciting to consider the potential for alternate genetic systems based on these analogous nucleosides — that these might possibly have emerged and evolved in different environments, perhaps even on other planets or moons within our solar system. These alternate genetic systems might expand our conception of biology's 'central dogma' into new evolutionary directions, in response and robust to increasingly challenging environments here on Earth."
When we search for extraterrestrial life, often we're looking for signs of RNA and DNA, but this may be an excessively narrow scope. After all, if millions of alternatives exist, there would need to be something very special indeed for life to universally favor using just DNA and RNA.
A new paper reveals that the Voyager 1 spacecraft detected a constant hum coming from outside our Solar System.
- Voyager 1, humankind's most distant space probe, detected an unusual "hum" in the data from interstellar space.
- The noise is likely produced by interstellar gas.
- Further investigation may reveal the hum's exact origins.
Voyager 1, humanity's most faraway spacecraft, has detected an unusual "hum" coming from outside our solar system. Fourteen billion miles away from Earth, the Voyager's instruments picked up a droning sound that may be caused by plasma (ionized gas) in the vast emptiness of interstellar space. Launched in 1977, the Voyager 1 space probe — along with its twin Voyager 2 — has been traveling farther and farther into space for over 44 years. It has now breached the edge of our solar system, exiting the heliosphere, the bubble-like region of space influenced by the sun. Now, the spacecraft is moving through the "interstellar medium," where it recorded the peculiar sound.
Stella Koch Ocker, a doctoral student in astronomy at Cornell University, discovered the sound in the data from the Voyager's Plasma Wave System (PWS), which measures electron density. Ocker called the drone coming from plasma shock waves "very faint and monotone," likely due to the narrow bandwidth of its frequency.
While they think the persistent background hum may be coming from interstellar gas, the researchers don't yet know what exactly is causing it. It might be produced by "thermally excited plasma oscillations and quasi-thermal noise."
The new paper from Ocker and her colleagues at Cornell University and the University of Iowa, published in Nature Astronomy, also proposes that this is not the last we'll hear of the strange noise. The scientists write that "the emission's persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events."
Voyager Captures Sounds of Interstellar Space www.youtube.com
The researchers think the droning sound may hold clues to how interstellar space and the heliopause, which can be thought of as the solar's system border, may be affecting each other. When it first entered interstellar space, the PWS instrument reported disturbances in the gas caused by the sun. But in between such eruptions is where the researchers spotted the steady signature made by the near-vacuum.
Senior author James Cordes, a professor of astronomy at Cornell, compared the interstellar medium to "a quiet or gentle rain," adding that "in the case of a solar outburst, it's like detecting a lightning burst in a thunderstorm and then it's back to a gentle rain."
More data from Voyager over the next few years may hold crucial information to the origins of the hum. The findings are already remarkable considering the space probe is functioning on technology from the mid-1970s. The craft has about 70 kilobytes of computer memory. It also carries a Golden Record created by a committee chaired by the late Carl Sagan, who taught at Cornell University. The 12-inch gold-plated copper disk record is essentially a time capsule, meant to tell the story of Earthlings to extraterrestrials. It contains sounds and images that showcase the diversity of Earth's life and culture.
As the American population grows, fewer people will die of cancer.
- A new study projects that cancer deaths will decrease in relative and absolute terms by 2040.
- The biggest decrease will be among lung cancer deaths, which are predicted to fall by 50 percent.
- Cancer is like terrorism: we cannot eliminate it entirely, but we can minimize its influence.
As the #2 leading cause of death, cancer takes the lives of about 600,000 Americans each year. In comparison, heart disease (#1) claims more than 650,000 lives, while accidents (#3) take about 175,000 lives. (In 2020 and likely 2021, COVID will claim the #3 spot.)
Headlines are usually full of terrible news about cancer. Seemingly, you can't get away from anything that causes it. RealClearScience made a list of all the things blamed for cancer — antiperspirants, salty soup, eggs, corn, Pringles, bras, burnt toast, and even Facebook made the list.
The reality, however, is much more optimistic. We're slowly but surely winning the war on cancer.
Winning the war on cancer
How can we make such a brazen statement? A new paper published in the journal JAMA Network Open tracks trends in cancer incidence and deaths and makes projections to the year 2040. The authors predict that around 568,000 Americans will have died of cancer in 2020, but they project that number to fall to 410,000 by 2040. That's a drop of nearly 28 percent, despite the U.S. population being projected to grow from roughly 333 million today to 374 million in 2040, an increase of 12 percent. That means cancer deaths will decrease in both relative and absolute terms.
What accounts for this unexpected good news? The lion's share is the number of deaths attributable to lung cancer, which is projected to decrease by more than 50 percent, from 130,000 to 63,000. This drop is largely due to the decreasing use of tobacco products. Other deaths predicted to decline include those from colorectal, breast, prostate, and ovarian cancers, among others, such as leukemia and non-Hodgkin lymphoma (NHL).
The authors credit screening and biomedical advances for saving many of these lives. For instance, lead author Dr. Lola Rahib wrote in an email to Big Think that "colonoscopies remove precancerous polyps." She also noted that targeted therapies and immunotherapies have helped reduce the number of deaths from leukemia and NHL.
We'll never cure cancer
Now the bad news: We'll never cure cancer. There are at least three reasons for this. The first is obvious: We all die. The lifetime prevalence of death is 100 percent. The truth is that we are running out of things to die from. After a long enough period of time, something gives out — often your cardiovascular system or nervous system. Or you develop you cancer.
The second reason is that we are multicellular organisms and, hence, we are susceptible to cancer. (Contrary to popular myth, sharks get cancer, too.) The cells of multicellular organisms face an existential dilemma: they can either get old and stop dividing (a process called senescence) or become immortal but cancerous. For this reason, the problem of cancer may not have a solution.
Finally, there isn't really such a thing as a disease called "cancer." What we call cancer is actually a collection of several different diseases, some of which are preventable (like cervical cancer with the HPV vaccine) or curable (like prostate cancer). Unfortunately, some cancers probably never will be curable, not least because cancers can mutate and develop resistance to the drugs we use to treat them.
But the overall optimism still stands: We are slowly and incrementally winning the war on cancer. Like terrorism, it's not a foe that we can completely vanquish, but it is one whose influence we can minimize in our lives.
China has reached a new record for nuclear fusion at 120 million degrees Celsius.
This article was originally published on our sister site, Freethink.
China wants to build a mini-star on Earth and house it in a reactor. Many teams across the globe have this same bold goal --- which would create unlimited clean energy via nuclear fusion.
But according to Chinese state media, New Atlas reports, the team at the Experimental Advanced Superconducting Tokamak (EAST) has set a new world record: temperatures of 120 million degrees Celsius for 101 seconds.
Yeah, that's hot. So what? Nuclear fusion reactions require an insane amount of heat and pressure --- a temperature environment similar to the sun, which is approximately 150 million degrees C.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it. In nuclear fusion, the extreme heat and pressure create a plasma. Then, within that plasma, two or more hydrogen nuclei crash together, merge into a heavier atom, and release a ton of energy in the process.
Nuclear fusion milestones: The team at EAST built a giant metal torus (similar in shape to a giant donut) with a series of magnetic coils. The coils hold hot plasma where the reactions occur. They've reached many milestones along the way.
According to New Atlas, in 2016, the scientists at EAST could heat hydrogen plasma to roughly 50 million degrees C for 102 seconds. Two years later, they reached 100 million degrees for 10 seconds.
The temperatures are impressive, but the short reaction times, and lack of pressure are another obstacle. Fusion is simple for the sun, because stars are massive and gravity provides even pressure all over the surface. The pressure squeezes hydrogen gas in the sun's core so immensely that several nuclei combine to form one atom, releasing energy.
But on Earth, we have to supply all of the pressure to keep the reaction going, and it has to be perfectly even. It's hard to do this for any length of time, and it uses a ton of energy. So the reactions usually fizzle out in minutes or seconds.
Still, the latest record of 120 million degrees and 101 seconds is one more step toward sustaining longer and hotter reactions.
Why does this matter? No one denies that humankind needs a clean, unlimited source of energy.
We all recognize that oil and gas are limited resources. But even wind and solar power --- renewable energies --- are fundamentally limited. They are dependent upon a breezy day or a cloudless sky, which we can't always count on.
Nuclear fusion is clean, safe, and environmentally sustainable --- its fuel is a nearly limitless resource since it is simply hydrogen (which can be easily made from water).
With each new milestone, we are creeping closer and closer to a breakthrough for unlimited, clean energy.