Navigation Links
Despite their heft, many dinosaurs had surprisingly tiny genomes

They might be giants, but many dinosaurs apparently had genomes no larger than that of a modern hummingbird.

So say scientists who've linked bone cell and genome size among living species and then used that new understanding to gauge the genome sizes of 31 species of extinct dinosaurs and birds, whose bone cells can be measured from the fossil record.

The researchers, at Harvard University and the University of Reading, were led by Chris Organ and Scott V. Edwards, both at Harvard. They report their findings this week in the journal Nature.

"We see distinct differences between two major lineages of dinosaurs," says Organ, a postdoctoral fellow in organismic and evolutionary biology supported by the National Institutes of Health. "The theropods -- carnivores such as Tyrannosaurus rex and Velociraptor -- had very small genomes, in the range of modern birds. Ornithischians -- which include Stegosaurus and Triceratops -- had more moderately sized genomes, akin to those of living lizards and crocodilians. We aren't sure about the genomes of the long-necked sauropods yet."

Organ and Edwards say the clear-cut dichotomy in dinosaur genomes is likely due to different amounts of repetitive and non-coding DNA in the two groups' genetic material, a factor largely responsible for variation in genome size across animal species. They estimate that active repetitive DNA might have comprised an average 12 percent of the ornithischian genome but just 8.4 percent of theropod genetic constitution.

The work indicates that the small genomes typically associated with birds -- whose genetic composition is noticeably sparer than that of other vertebrates -- evolved in dinosaurs some 230 to 250 million years ago, rather than with the emergence of modern living birds just 110 million years ago. Organ and Edwards suggest after this shrinking, theropod genomes then stabilized in size for hundreds of millions of years, a process that continues in mo dern birds.

"Our work debunks the theory that the small, repeat-poor genomes typical of birds may have co-evolved with flight as a means of conserving energy," says Edwards, professor of organismic and evolutionary biology in Harvard's Faculty of Arts and Sciences and Alexander Agassiz Professor of Zoology and curator of ornithology in Harvard's Museum of Comparative Zoology. "In fact, our work shows these streamlined genomes arose long before the first birds and flight, and can be added to the list of dinosaur traits previously thought to be found only in modern birds, including feathers, pulmonary innovations, and parental care and nesting."

Other researchers had previously determined that the sizes of various cell types, across species, tend to reflect the size of an organism's genome. Analyzing 26 living species, Organ and Edwards are the first to show that the same applies to the bone cells called osteocytes.

These cells reside in individual lacunae, small pockets inside bone tissue. This uniquely durable cellular housing allowed the scientists to look back in time at the size of 31 extinct species' genomes: By measuring lacunae in dinosaur and extinct bird specimens housed at Harvard's Museum of Comparative Zoology and at the Museum of the Rockies in Bozeman, Mont., they were able to determine just how big the various extinct species' osteocytes had been.

"These fossils let us sample species through evolutionary time," Edwards says, "providing genomic information that's often unavailable for long-extinct ancestors."


'"/>

Source:Harvard University


Related biology news :

1. Despite acidity, orange juice could still be a source of foodborne disease
2. Priming embryonic stem cells to fulfill their promise
3. Protein offers way to stop microscopic parasites in their tracks
4. Flocking together: Study shows how animal groups find their way
5. Where bacteria get their genes
6. Chickadees can help humans get their bearings
7. Bacteria use hosts immune response to their competitive advantage
8. Structures of marine toxins provide insight into their effectiveness as cancer drugs
9. Beauty queens urge girls not to sacrifice their bones
10. Researchers learn how blood vessel cells cope with their pressure-packed job
11. Stem cells electric abilities might help their safe clinical use
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:5/3/2016)... 2016  Neurotechnology, a provider of high-precision biometric ... Biometric Identification System (ABIS) , a complete system ... ABIS can process multiple complex biometric transactions with ... fingerprint, face or iris biometrics. It leverages the ... MegaMatcher Accelerator , which have been used ...
(Date:4/28/2016)... and BANGALORE, India , April 28, ... Systems, a product subsidiary of Infosys (NYSE: INFY ... announced a global partnership that will provide end ... use mobile banking and payment services.      (Logo: ... key innovation area for financial services, but it also plays ...
(Date:4/28/2016)... , April 28, 2016 First quarter ... (139.9), up 966% compared with the first quarter of 2015 ... totaled SEK 589.1 M (loss: 18.8) and the operating margin was ... (loss: 0.32) Cash flow from operations was SEK 249.9 ... 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. The ...
Breaking Biology News(10 mins):
(Date:5/5/2016)... ... May 05, 2016 , ... American ... two additional patents, U.S. Patent Nos. 9,322,133 and 9,322,134, to API and its ... nanocellulose as well as hydrophobic nanocellulose compositions. In addition to these patents ...
(Date:5/5/2016)... BELL, Pa. , May 5, 2016  Why ... Powers and Lorna Weir launching a ... un-agency way? Because they believe that truly helping clients ... world of healthcare now demands a different type of ... strategy lab serving the pharmaceutical, biotechnology and medical device ...
(Date:5/5/2016)... , ... May 05, 2016 , ... ... previously announced identification of its first three targets, it has identified a fourth ... beta (Aß), implicated in the development and progression of Alzheimer’s disease (AD). ...
(Date:5/4/2016)... ... 2016 , ... CereScan, the nation’s leader in providing statistically ... Stroke Awareness Month in May. An infographic created by CereScan will be ... will donate $1 up to a maximum of $3,000 through users who share ...
Breaking Biology Technology: