RNA-only genes: ancient infections hide in human genome and get themselves passed from generation to generation

From the Economist:

Not so long ago, received wisdom was that most of the human genome—99% of it—was “junk”. If this junk had a role, it was just to space out the remaining 1%, the genes in which instructions about how to make proteins are encoded.

That, it now seems, was far from the truth. The decade since the completion of the Human Genome Project has shown that lots of the junk must indeed have a function. Almost two-thirds of human DNA, rather than just 1% of it, is being copied into molecules of RNA. As a consequence, rather than there being just 23,000 genes, there may be millions of them.


Human chromosomes (grey) capped by telomeres (white). Image source: Wikipedia, public domain.

One new genetic class is known as lincRNAs. Molecules of lincRNA are similar to the messenger-RNA molecules which carry protein blueprints. However, they do not encode proteins. More than 9,000 sorts are known, and their job is the regulation of other genes.

LincRNA is rather odd, though. It often contains members of a second class of weird genetic object. These are called transposable elements - “jumping genes” - because their DNA can hop from one place to another within the genome. Transposable elements come in several varieties, but one group of particular interest are known as endogenous retroviruses. These are the descendants of ancient infections that have managed to hide away in the genome and get themselves passed from generation to generation along with the rest of the genes.

This Nature video takes you on an audio-visual journey, diving into a cell to show how genes are transcribed to make messenger RNA (mRNA) and how RNAi can silence specific mRNAs to stop them from making proteins:



References:

RNA-only genes: The origin of species? The Economist.

Night shift workers are fighting ancient rhythms that order them to hunt or forage

From the National Geographic Magazine:

We sleep 1.5 hour less a night than we did just 100 years ago

We sleep on average 1.5 hour less a night than we did just a century ago. Some of our epidemic of insomnia or sleeplessness is probably just our refusal to pay attention to our biology. The natural sleep rhythms of teenagers would call for a late morning wake-up—but there they are, starting high school at 8 a.m.

The night shift worker sleeping in the morning is fighting ancient rhythms in his or her body that order him or her awake to hunt or forage when the sky is flooded with light. Yet he or she has no choice.

We fight these forces at our peril. Harvard's researchers note that going without sleep for 24 hours or getting only 5 hours of sleep a night for a week is the equivalent of a blood alcohol level of 0.1 percent. Yet modern business ethic celebrates such feats. "We would never say, 'This person is a great worker! He's drunk all the time!' "

One in 20 medical residents admits to making a fatigue-related mistake that resulted in the death of a patient

A 2004 study included 2,700 first-year medical residents. These young men and women worked shifts that were as long as 30 hours twice a week. The research revealed the remarkable public health risk that this sleep debt entailed. "We know that one out of five first-year residents admits to making a fatigue-related mistake that resulted in injury to a patient. One in 20 admits to making a fatigue-related mistake that resulted in the death of a patient. One day people will look back on what will be viewed as a barbarous practice."

References:

The Secrets of Sleep. National Geographic Magazine, 2011.

Image source: A halo around the Moon. Wikipedia, GNU Free Documentation License.