Navigation Links
How the mole got its 12 fingers

This release is available in German.

Polydactyly is a hereditary anomaly that is relatively common in both humans and animals. Moles also have additional fingers. In their case, however, the irregularity compared to the five-finger formula of land vertebrates is the norm. An international team of researchers head-ed by paleontologists from the University of Zurich has now uncovered the background to the development of the mole's extra "thumb": A bone develops in the wrist that stretches along the real thumb, giving the paw a bigger surface area for digging.

Most pawed animals have ten fingers. One of the main exceptions is the little mole: It has an extra "thumb", which it rests upon while digging and thus increases the size of its digging apparatus. Poly-dactyly the presence of supernumerary fingers is a phenomenon that has already been observed in various land animals in Devon and is also fairly common in humans, dogs and cats. Land verte-brates appear to possess a silent developmental program for polydactyly, which is only activated un-der certain conditions. In moles, however, polydactyly is the norm, which means the program is con-stantly activated during embryogenesis.

An international team of researchers headed by Marcelo Snchez-Villagra, a professor of paleontolo-gy at the University of Zurich, has studied the molecular-genetic origin and development of the extra thumb in moles. As the scientists reveal in their recent article published in the journal Biology Letters, the additional thumb develops later and differently during embryogenesis than the real fingers. The studies were funded by the Swiss National Science Foundation.

Unlike the other fingers on the mole's hand, the extra thumb does not have moving joints. Instead, it consists of a single, sickle-shaped bone. Using molecular markers, the researchers can now show for the first time that it develops later than the real fingers from a transformed sesamoid bone in the wrist. In shrews, however, the mole's closest relative, the extra thumb is lacking, which confirms the re-searchers' discovery.

Male hormones linked to polydactyly

The researchers see a connection between the species-specific formation of the extra thumb in the mole and the peculiar "male" genital apparatus of female moles. In many mole species, the females have masculinized genitals and so-called "ovotestes", i.e. gonads with testicular and ovary tissue instead of normal ovaries. Androgenic steroids are known to influence bone growth, transformation and changes, as well as the transformation of tendons in joints. A high level of maternal testosterone is also thought to be one of the causes of polydactyly in humans.


Contact: Marcelo Sanchez
University of Zurich

Related biology news :

1. MIT researchers explain mystery of gravity fingers
2. Let your fingers do the driving
3. Mixing fluids efficiently in confined spaces: Let the fingers do the working
Post Your Comments:
Related Image:
How the mole got its 12 fingers
(Date:6/1/2016)... June 1, 2016 Favorable Government ... Administration and Criminal Identification to Boost Global Biometrics System ... released TechSci Research report, " Global Biometrics Market ... Forecast and Opportunities, 2011 - 2021", the global biometrics ... 2021, on account of growing security concerns across various ...
(Date:5/9/2016)... 2016 Elevay is currently known ... freedom for high net worth professionals seeking travel for ... connected world, there is still no substitute for a ... sealing your deal with a firm handshake. This is ... advantage of citizenship via investment programs like those offered ...
(Date:4/26/2016)... DUBLIN , April 27, 2016 ... of the  "Global Multi-modal Biometrics Market 2016-2020"  report ... ) , The analysts forecast ... a CAGR of 15.49% during the period 2016-2020.  ... a number of sectors such as the healthcare, ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... , June, 23, 2016  The Biodesign Challenge ... envision new ways to harness living systems and biotechnology, ... Art (MoMA) in New York City ... 130 participating students, showcased projects at MoMA,s Celeste Bartos ... Paola Antonelli , MoMA,s senior curator of architecture and ...
(Date:6/23/2016)... ... 2016 , ... Supplyframe, the Industry Network for electronics hardware ... . Located in Pasadena, Calif., the Design Lab’s mission is to bring together ... built and brought to market. , The Design Lab is Supplyframe’s physical representation ...
(Date:6/23/2016)... ... , ... In a new case report published today in STEM CELLS Translational ... lymphedema after being treated for breast cancer benefitted from an injection of stem cells ... this debilitating, frequent side effect of cancer treatment. , Lymphedema refers to ...
(Date:6/23/2016)... 23, 2016  Blueprint Bio, a company dedicated to ... medical community, has closed its Series A funding round, ... "We have received a commitment from Forentis ... need to meet our current goals," stated Matthew ... runway to complete validation on the current projects in ...
Breaking Biology Technology: