Short RNAs show a long history

Oct 01, 2008

MicroRNAs, the tiny molecules that fine-tune gene expression, were first discovered in 1993. But it turns out they've been around for a billion years.

Evidence reported in Nature on October 1 by scientists in the lab of Whitehead Member and Howard Hughes Medical Institute investigator David Bartel provides a window into the early evolution of these key regulators, placing their origin within the earliest of animal lineages. The research also suggests that microRNAs present early on have undergone extensive changes, which likely have altered their functions across various lineages.

"This is the first evidence that microRNAs were present within the earliest animal lineages and are not just characteristic of more complex animals," says Andrew Grimson, a postdoctoral fellow in Bartel's lab. Scientists knew that microRNAs existed within bilaterians, an evolutionary group that includes everything from worms to fruit flies to humans, he explains. "Remarkably, we discovered their presence within sponge, a member of the earliest diverging group of animals."

The scientists used high-throughput sequencing to probe samples from animals that diverged before the origin of bilaterian animals. The sponge (Amphimedon queenslandica) represents a group of animals that split off in evolution very early, whereas the starlet sea anemone (Nematostella vectensis) split off more recently.

The sequences of microRNAs within each lineage were different from each other, suggesting that microRNA functions are almost certainly very different in these different lineages. "In a relatively narrow spectrum of evolution microRNAs are often conserved," says Grimson. "But in a broader spectrum they have completely changed. This suggests that microRNA evolution is more flexible and may be evolving more rapidly than suspected."

Researchers also pinpointed piRNAs, another class of small RNAs, among these two species. Although less is known about piRNAs, they characteristically have longer sequences than microRNAs and are thought to dampen the activity of transposons—chunks of DNA that can move around the genome, causing mutations.

"It appears that both microRNAs and piRNAs have been available to shape gene expression throughout the evolution of animals and perhaps even helped to usher in the era of multicellular animal life," says Bartel.

Citation: "The Early Origins and Evolution of microRNAs and piRNAs in Animals", Nature on-line, Oct. 1, 2008

Source: Whitehead Institute for Biomedical Research

Explore further: Rare Sri Lankan leopards born in French zoo

add to favorites email to friend print save as pdf

Related Stories

Rainbow trout genome sequenced

Apr 22, 2014

Using fish bred at Washington State University, an international team of researchers has mapped the genetic profile of the rainbow trout, a versatile salmonid whose relatively recent genetic history opens ...

Sea anemone is genetically half animal, half plant

Mar 18, 2014

The team led by evolutionary and developmental biologist Ulrich Technau at the University of Vienna discovered that sea anemones display a genomic landscape with a complexity of regulatory elements similar ...

A surprising new function for small RNAs in evolution

Apr 19, 2013

An international research team in including Christian Schlötterer and Alistair McGregor of the Vetmeduni Vienna has discovered a completely new mechanism by which evolution can change the appearance of an ...

Recommended for you

Rare Sri Lankan leopards born in French zoo

1 minute ago

Two rare Sri Lankan leopard cubs have been born in a zoo in northern France, a boost for a sub-species that numbers only about 700 in the wild, the head of the facility said Tuesday.

Japan wraps up Pacific whale hunt

41 minutes ago

Japan announced Tuesday that it had wrapped up a whale hunt in the Pacific, the second campaign since the UN's top court ordered Tokyo to halt a separate slaughter in the Antarctic.

Researchers uncover secrets of internal cell fine-tuning

51 minutes ago

New research from scientists at the University of Kent has shown for the first time how the structures inside cells are regulated – a breakthrough that could have a major impact on cancer therapy development.

Getting a jump on plant-fungal interactions

1 hour ago

Fungal plant pathogens may need more flexible genomes in order to fully benefit from associating with their hosts. Transposable elements are commonly found with genes involved in symbioses.

Algae under threat from invasive fish

1 hour ago

Tropical fish invading temperate waters warmed as a result of climate change are overgrazing algae, posing a threat to biodiversity and some marine-based industries.

User comments : 0