We revisit last year’s COVID-19 questions, readers weigh in on tuataras and more

Seeing double

New Zealand’s lizardlike tuatara is the first known vertebrate with two mitochondrial genomes, Devin A. Reese reported in “The tuatara hides an extra set of genes” (SN: 2/27/21, p. 10).

Reader Alfonso Solimano wondered if each mitochondrion in tuatara cells has a copy of both genomes.

The two genomes likely don’t exist in a single mitochondrion, says genomicist Robert Macey of the Peralta Genomics Institute in Oakland, Calif. How DNA is arranged in the organelle is unknown. It’s possible that the 200 to 1,200 mitochondria in a single cell could house both genomes, with one version per mitochondrion, Macey says. Or perhaps only one of the two genomes appears in a single cell.

Turn up the heat

Diamond retains its structure even when compressed to more than five times the pressure in Earth’s core, Emily Conover reported in “Diamond holds up under pressure” (SN: 2/27/21, p. 15).

Reader Robert Stenton asked what would happen to diamond if scientists also subjected the material to about 6000° Celsius, the temperature at Earth’s center.

When researchers pummeled diamond with powerful lasers, they not only increased the pressure in the material, but also raised its temperature to thousands of degrees C, Conover says. In fact, the diamond got hot enough that the scientists thought it might melt. But that’s not what happened. “The result actually raises two puzzling issues: Why the diamond didn’t convert to another phase, and why it didn’t melt,” she says.

Harvesting energy

The Milky Way emanates gamma rays with energies approaching a quadrillion electron volts, Emily Conover reported in “Milky Way’s glow is highly energetic” (SN: 2/27/21, p. 12).

Reader Mark Blackham wondered if it is possible to harness those gamma rays for practical use.

Such high-energy particles are rare and difficult to detect, Conover says. And while a quadrillion electron volts is a huge amount of energy for a single fundamental particle to carry, it’s not that impressive on a macroscopic scale. A flying mosquito’s kinetic energy, for example, is about 1 trillion electron volts. The gamma rays that researchers found each carried the energy of hundreds of mosquitoes, Conover says. “I don’t think it would be particularly useful to try to harvest this energy.”


Science News reporters Tina Hesman Saey, Aimee Cunningham, Jonathan Lambert and Erin Garcia de Jesús are following the latest research to keep you up to date on the coronavirus pandemic. A year in, we revisit reader questions about COVID-19 from the April 11, 2020 issue.

Reader Ken M. asked a year ago if there are two versions of the coronavirus, one that causes mild symptoms and another that has more severe effects.

In April 2020, there weren’t two versions of the virus going around in the United States or elsewhere. Now that’s no longer the case. Multiple variants of the coronavirus are circulating globally. The new variants seem to spread more easily and quickly than the original.

“Why are people in such a tizzy about [COVID-19]?” reader Joe B. asked at the time. In the United States, influenza seems like a much bigger cause for concern, he wrote.

Even a year ago, scientists knew that COVID-19 killed at a higher rate than the flu. COVID-19 has now killed 2.7 million people globally as of late March 2021, with more than half a million deaths in the United States. Meanwhile, social distancing, mask wearing and other efforts to reduce the spread of the coronavirus probably sent cases of flu and other respiratory diseases plummeting (SN Online: 2/2/21).

Even as COVID-19 vaccines become more widely available, experts worry a surge in cases may be on the horizon as more contagious variants spread (SN: 3/27/21, p. 6) and some U.S. states begin to lift public health restrictions.