Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Evolutionary Biology: Why Cattle Only Have two Toes

20.06.2014

During evolutionary diversification of vertebrate limbs, the number of toes in even-toed ungulates such as cattle and pigs was reduced and transformed into paired hooves.

Scientists at the University of Basel have identified a gene regulatory switch that was key to evolutionary adaption of limbs in ungulates. The study provides fascinating insights into the molecular history of evolution and is published by Nature today.

The fossil record shows that the first primitive even-toed ungulates had legs with five toes (=digits), just like modern mice and humans. During their evolution, the basic limb skeletal structure was significantly modified such that today’s hippopotami have four toes, while the second and fifth toe face backwards in pigs. In cattle, the distal skeleton consists of two rudimentary dew claws and two symmetrical and elongated middle digits that form the cloven hoof, which provides good traction for walking and running on different terrains.

Comparative analysis of embryonic development

A team led by Prof. Rolf Zeller from the Department of Biomedicine at the University of Basel has now investigated the molecular changes which could be responsible for the evolutionary adaptation of ungulate limbs. To this aim, they compared the activity of genes in mouse and cattle embryos which control the development of fingers and toes during embryonic development.

The development of limbs in both species is initially strikingly similar and molecular differences only become apparent during hand and foot plate development: in mouse embryos the so-called Hox gene transcription factors are distributed asymmetrically in the limb buds which is crucial to the correct patterning of the distal skeleton. In contrast, their distribution becomes symmetrical from early stages onward in limb buds of cattle embryos: “We think this early loss of molecular asymmetry triggered the evolutionary changes that ultimately resulted in development of cloven-hoofed distal limb skeleton in cattle and other even-toed ungulates”, says Developmental Geneticist Prof. Rolf Zeller.

Loss of asymmetry preceded the reduction and loss of digits

The scientists in the Department of Biomedicine then focused their attention on the Sonic Hedgehog (SHH) signaling pathway, as it controls Hox gene expression and the development of five fingers and toes in mice and humans. They discovered that the gene expression in limb buds of cattle embryos is altered, such that the cells giving rise to the distal skeleton fail to express the Hedgehog receptor, called Patched1. Normally, this receptor serves as an antenna for SHH, but without Patched1 the SHH signal cannot be received and the development of five distinct digits is disrupted. The researchers could establish that the altered genomic region – a so-called cis-regulatory module – is linked to the observed loss of Patched1 receptors and digit asymmetry in cattle embryos.

“The identified genetic alterations affecting this regulatory switch offer unprecedented molecular insights into how the limbs of even-toed ungulates diverged from those of other mammals roughly 55 million years ago”, explains Rolf Zeller. At this stage, it is unclear what triggered inactivation of the Patched1 gene regulatory switch. “We assume that it is the result of progressive evolution, as this switch degenerated in cattle and other even-toed ungulates, while it remained fully functional in some vertebrates such as mice and humans”.

Original source
Javier Lopez-Rios, Amandine Duchesne, Dario Speziale, Guillaume Andrey, Kevin A. Peterson, Philipp Germann, Erkan Ünal, Jing Liu, Sandrine Floriot, Sarah Barbey, Yves Gallard, Magdalena Müller-Gerbl, Andrew D. Courtney, Christophe Klopp, Sabrina Rodriguez, Robert Ivanek, Christian Beisel, Carol Wicking, Dagmar Iber, Benoit Robert, Andrew P. McMahon, Denis Duboule and Rolf Zeller
Attenuated sensing of SHH by Ptch1 underlies evolution of bovine limbs
Nature (2014) | doi: 10.1038/nature13289

Further information
Prof. Dr. Rolf Zeller, University of Basel, Department of Biomedicine, phone: +41 61 695 30 33, email: rolf.zeller@unibas.ch

Weitere Informationen:

http://dx.doi.org/10.1038/nature13289 - Abstract

Reto Caluori | Universität Basel

Further reports about: Biology Cattle Evolutionary Hedgehog asymmetry embryos fingers limbs regulatory skeleton

More articles from Life Sciences:

nachricht A cell senses its own curves: New research from the MBL Whitman Center
29.04.2016 | Marine Biological Laboratory

nachricht A New Discovery in the Fight against Cancer: Tumor Cells Switch to a Different Mode
29.04.2016 | Universität Basel

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Tiny microbots that can clean up water

Researchers from the Max Planck Institute Stuttgart have developed self-propelled tiny ‘microbots’ that can remove lead or organic pollution from contaminated water.

Working with colleagues in Barcelona and Singapore, Samuel Sánchez’s group used graphene oxide to make their microscale motors, which are able to adsorb lead...

Im Focus: ORNL researchers discover new state of water molecule

Neutron scattering and computational modeling have revealed unique and unexpected behavior of water molecules under extreme confinement that is unmatched by any known gas, liquid or solid states.

In a paper published in Physical Review Letters, researchers at the Department of Energy's Oak Ridge National Laboratory describe a new tunneling state of...

Im Focus: Bionic Lightweight Design researchers of the Alfred Wegener Institute at Hannover Messe 2016

Honeycomb structures as the basic building block for industrial applications presented using holo pyramid

Researchers of the Alfred Wegener Institute (AWI) will introduce their latest developments in the field of bionic lightweight design at Hannover Messe from 25...

Im Focus: New world record for fullerene-free polymer solar cells

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences (CAS). This work is about avoiding costly and unstable fullerenes.

Polymer solar cells can be even cheaper and more reliable thanks to a breakthrough by scientists at Linköping University and the Chinese Academy of Sciences...

Im Focus: Ultra-thin glass is up and coming

As one of the leading R&D partners in the development of surface technologies and organic electronics, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP will be exhibiting its recent achievements in vacuum coating of ultra-thin glass at SVC TechCon 2016 (Booth 846), taking place in Indianapolis / USA from May 9 – 13.

Fraunhofer FEP is an experienced partner for technological developments, known for testing the limits of new materials and for optimization of those materials...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

The “AC21 International Forum 2016” is About to Begin

27.04.2016 | Event News

Soft switching combines efficiency and improved electro-magnetic compatibility

15.04.2016 | Event News

Grid-Supportive Buildings Give Boost to Renewable Energy Integration

12.04.2016 | Event News

 
Latest News

Winds a quarter the speed of light spotted leaving mysterious binary systems

29.04.2016 | Physics and Astronomy

Fiber optic biosensor-integrated microfluidic chip to detect glucose levels

29.04.2016 | Health and Medicine

A cell senses its own curves: New research from the MBL Whitman Center

29.04.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>