Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Medical Nanoimaging Pinpoints Cause of Cataracts

16.10.2007
At the Institut Curie, Simon Scheuring, beneficiary of the Inserm Avenir program and coordinator of the CNRS/Inserm “Atomic force microscopy (AFM) of proteins in native membranes” team(1), has for the first time observed a diseased tissue at very high resolution using atomic force microscopy (AFM).

By studying the membranes of cells in a patient’s eye cataract, Scheuring has discovered the molecular cause of this disease. This is the first time that high-resolution AFM imaging of a diseased tissue has yielded information on the single molecule level of the disease. AFM has emerged from the state-of-the-art laboratory to bring us medical nanoimaging. These results are now online in the Journal of Molecular Biology.

The eye’s lens focuses light and forms a sharp image on the retina thanks to the organization and specific properties of its constituent cells (see box overleaf). As in all tissues, cellular exchanges are essential for nutrition and removal of waste products, but in the eye they must nonetheless be adapted to the particular properties of the lens. The membranes of lens cells contain protein assemblies, the aquaporins and connexons (2): the former act as water channels and the latter as channels for metabolites and ions. Together these membrane proteins ensure cell adhesion.

Using atomic force microscopy (AFM), which images the surface of a sample at a precision of one nanometer (one billionth of a meter), Simon Scheuring’s team at the Institut Curie is studying how these protein assemblies function. An atomically sharp tip is scanned over the sample surface and its movements are tracked by a laser. The resulting data can be used to draw a topographical map of the sample. By comparing assemblies of aquaporins and connexons in membranes of healthy and diseased lens cells, Scheuring and colleagues have identified the biological changes that cause cataracts (see box overleaf).

In this senile cataract, lack of connexons prevents formation of the channels ensuring cell to cell communication. These molecular modifications explain the lack of adherence between cells, waste accumulation in cells, and the defective transport of water, ions, and metabolites in a lens with a cataract.

This is the first time that high-resolution AFM imaging of diseased tissue has shed light on the molecular cause of a disease at the single membrane protein level. A step towards medical nanoimaging has been taken with atomic force microscopy.

The lens
The specific properties of the eye’s lens cells enable the lens to function correctly. These cells have no nucleus or organelles, such as mitochondria, and are unable to perform certain biochemical functions essential for their nutrition, and therefore depend on transmembrane channels (3) for transport of water, ions, and metabolites, and for waste removal. These cells are full of so-called lens proteins (crystallins), which ensure lens transparency. To avoid any loss of light, the lens is avascular and its network of cells is extremely compact: the gap between neighboring cells must be less than the wavelength of visible light.
The cataract
The cataract results from opacification linked to the hardening of the lens. Age-related (senile) cataracts are by far the commonest, and affect more than one in five of the over-65s, over one in three of the over-75s, and two thirds of people over 85 years of age. Cataracts cause reduced image sharpness, blurred vision, and sensitivity to light and glare. The only effective treatment for cataracts at present is surgery, in which the opaque lens is removed and replaced by an artificial lens. Cataracts are the main cause of blindness in the third world and explain the sight loss of 40% of the world’s 37 million blind.
(1) “Atomic force microscopy of proteins in native membranes” team in the Curie Physical Chemistry research unit UMR 168 CNRS/Institut Curie directed by Jean-François Joanny.
(2) A connexon is an assembly of 6 connexin molecules and forms a gap junction between the cytoplasm of two adjacent cells.
(3) “The supramolecular architecture of junctional microdomains in native lens membranes”

N. Buzhynskyy, R. Hite, T. Walz, S Scheuring. EMBO R. January 2007, vol. 8, p. 51-55.

Catherine Goupillon | alfa
Further information:
http://www.sciencedirect.com/science/journal/00222836

Further reports about: AFM Cataracts Microscopy Scheuring cataract connexon diseased

More articles from Life Sciences:

nachricht Single-stranded DNA and RNA origami go live
15.12.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht New antbird species discovered in Peru by LSU ornithologists
15.12.2017 | Louisiana State University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>