National Geographic

Dinosaur Embryos, Lost Butterflies and Cancer Genes, Oh My

Beyond this blog, I also cover science news for Nature and The Scientist. I tease and expand on some of these, but here’s a compendium of the ones that have fallen through the sieve, with taster paragraphs.

Dinosaur Embryo Graveyard - A treasure trove of fossilized dinosaur embryos shows signs of extremely fast growth.

Sometime in the early Jurassic period, between 190 and 197 million years ago, a flood swept through a dinosaur nesting site in what is now southern China. Dozens of embryos were suffocated in their eggs and their bones were separated from each other, carried away, and buried under sediment.

Today, this site hosts the largest collection of fossilised dinosaur embryos ever discovered. Robert Reisz from the University of Toronto used this treasure trove to reconstruct the growth of dinosaur embryos at unprecedented detail. “We could look at the internal anatomy of the bones to see how fast they grew, which was really quite amazing,” he said.

Monarch butterflies navigate with compass but no map

Every autumn, millions of monarch butterflies (Danaus plexippus) converge on a small cluster of Mexican mountains to spend the winter. They have journeyed for up to 4,000 kilometres from breeding grounds across eastern North America. And according to a study, they accomplish this prodigious migration without ever knowing where they are relative to their destination.

The monarchs can use the position of the Sun as a compass, but when Henrik Mouritsen, a biologist at the University of Oldenburg in Germany, displaced them by 2,500 kilometres, he found that they did not correct their heading. “People seemed to assume that they had some kind of a map that allowed them to narrow in on a site a few kilometres across after travelling several thousands of kilometres,” he says. Now, “it is clear that they don’t”.

Life found deep under the sea – Oceanic-crust microbes survive on hydrogen and carbon dioxide.

For the first time, scientists have discovered microbes living deep inside Earth’s oceanic crust — the dark volcanic rock at the bottom of the sea. This crust is several kilometres thick and covers 60% of the planet’s surface, making it the largest habitat on Earth.

The microbes inside it seem to survive largely by using hydrogen, formed when water flows through the iron-rich rock, to convert carbon dioxide into organic matter. This process, known as chemosynthesis, is distinct from photosynthesis, which uses sunlight for the same purpose.

Chemosynthesis also fuels life at other deep-sea locations such as hydrothermal vents, but those are restricted to the edges of continental plates. The oceanic crust is much bigger. If similar microbes are found throughout it, the crust “would be the first major ecosystem on Earth to run on chemical energy rather than sunlight”, says Mark Lever, an ecologist at Aarhus University in Denmark, who led the study.

The Falsity of Living Fossils – New studies of tadpole shrimp and other organisms show that the term “living fossil” is inaccurate and misleading.

Today’s tadpole shrimp, or notostracans, have a shield-shaped body, ending in a forked pair of filaments—a shape that makes them almost indistinguishable from their ancestors in the Triassic period some 265 million years ago. This outward constancy has earned them the description of “living fossils”—a term referring to species with no close living relatives, which seem to have gone unchanged for long spans of time.

But according to a genetic analysis of notostracans published today in PeerJ, these animals have by no means stopped evolving. Indeed, researchers are coming to realize that the term “living fossil” is a misnomer. One by one, the classic examples—horseshoe crabs, coelacanths, cycads, and more—have turned out to be very different from the fossils that they apparently resemble, either at a genetic level or through subtle physical changes. Their recognizable nature is a red herring—these creatures simply did not exist in their current form millions of years ago.

“I would favor retiring the term ‘living fossil’ altogether as it is generally misleading,” said Africa Gomez at the University of Hull who led the study.

Sequencing the Underdogs – Transcriptome studies reveal new insights about unusual animals whose genomes have not been sequenced.

The red spotted newt (Notophthalmus viridescens) could sit in the palm of your hand, but its genome is ten times the size of yours—up to 10 billion base pairs. This daunting amount of DNA has kept this species off the radar of any genome sequencing projects, despite plummeting costs. It has also prevented newts and salamanders from becoming regular model organisms, despite their remarkable and medically-relevant ability to regenerate severed limbs and damaged organs.

Recently, a team of German scientists circumvented the difficulties posed by the newt’s huge genome by sequencing its transcriptome instead—the set of RNA produced from its genes. Since some of an animal’s genome is never transcribed, transcriptomes can often be decoded at a fraction of the cost and effort of a full genome, and the newt results are part of a growing trend of using transcriptomes to understand lesser-known species.

The Science of Head Trauma – Research nears a biomarker for the contact-sport-associated disease that affects athletes long after they’ve retired.

In May 2012, former National Football League (NFL) player Junior Seau shot himself in the chest. An autopsy, conducted by the National Institutes of Health, revealed that Seau suffered from chronic traumatic encephalopathy (CTE)—a condition where repeated blows to the head, even mild ones, can trigger the progressive loss of brain tissue. He was the latest of a number of former athletes who have taken their own lives and were the discovered to have the neurological hallmarks of the disease. The string of suicides has pushed awareness of CTE to fever pitch, and earlier this week, the NFL and General Electric jointly pledged $60 million over 4 years to research on diagnosing and treating brain trauma.

CTE has a long history. It was first documented in the 1920s by New Jersey medical examiner Harrison Martland, who noticed that boxers slowly developed a form of dementia after repeated blows to the head. Described initially as “punch drunk” or “dementia pugilistica,” the condition was later renamed as CTE after researchers realized that it could be caused by activities other than boxing. The recent discovery that young athletes can also suffer from the condition has spurred a surge of interest. “The field has exploded,” said Ann McKee from Boston University. “It can’t believe what’s happened in 5 years.”

Cancer Gene Bonanza – International collaboration doubles the number of genetic regions associated with breast, prostate, and ovarian cancers.

The largest genetic association study in cancer thus far has unveiled dozens of previously unknown genetic regions that affect the risk of breast, prostate, and ovarian cancer. These discoveries provide fresh clues about the biology of these cancers, as well as pave the way to more accurate assessments of individual risk. The results are described in 13 papers, published today in Nature Genetics and several other journals.

Although it is clear that these hormone-related cancers have a strong genetic component, the variants identified in previous studies only account for a small proportion of this inherited susceptibility. To uncover more regions, an international team of scientists formed the Collaborative Oncological Gene-environment Study (COGS). They pooled the results from earlier studies to create a single chip called iCOGS, which they used to assess 211,000 single nucleotide polymorphisms (SNPs) of interest in the genomes of more than 200,000 people.

Together, they identified 74 new SNPs that affect the risk of these three cancers. “The sheer number of new variants was probably more than a lot of people were expecting,” said Doug Easton from the University of Cambridge, one of the study’s senior investigators.

There are 3 Comments. Add Yours.

  1. TK
    April 15, 2013

    What were the plausible navigation mechanisms that the monarch butterfly experiment rules out? If someone kidnapped me, transported me due west, and put me in a cylinder which allowed me to see only the sky, then of course I wouldn’t know where I was, unless I had a bionic GPS, or the ability to calculate longitude based on my circadian clock. So I guess we know the butterflies don’t have either of those powers. But are there any other environmental cues they could theoretically have picked up on, that are ruled out by this new experiment?

    [A magnetic sense. See this post for an equivalent experiment with turtles, who fare much better than the monarchs. - Ed]

  2. TK
    April 16, 2013

    Whoa. Mind blown. Thanks, Ed.

  3. Tina
    April 18, 2013

    Cool Beans.

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