Transport Tubes Plugged When Damaged

close up view of fava beans in their pods

Biological Strategy

Fava bean

AskNature Team

Image: beautifulcataya / Flickr / CC BY - Creative Commons Attribution alone

Transform Mechanical Energy

Mechanical energy is made up of kinetic energy (the energy of an object in motion) and potential energy (stored energy). Organisms use mechanical energy in a variety of ways, including capturing prey, transporting seeds, and moving around.

Search this Function

Manage Shear

The effect of shear stress on a living system is parallel internal surfaces sliding past each other. Slippage occurs in parallel with the force. Think about holding two wooden boards on top of each other and sliding one to the right and the other to the left. This may be easy until you add glue, which increases their shear strength and makes them harder or impossible to slide. Shear can occur in solids, liquids, and gases. Living systems must increase their shear strength to overcome these types of forces. For example, darkling beetles lock their wings together in flight to prevent lateral movement by using many small hairs on each wing. These hairs interlock to provide shear strength, just as two hair brushes put together would be difficult to slide past each other.

Search this Function

Protect From Loss of Liquids

Water is essential to life. Liquids, mostly water, make up 70 to 90% of all living systems, and the loss of even a small percentage can mean the difference between life and death. Living systems must maintain a proper liquid balance, which is especially difficult in dry conditions. To do so, they must control the movement of liquids across their boundaries. Living systems do this using structures or waterproof materials to prevent or slow liquid movement. For example, when humans receive a cut, they must limit blood loss. Scattered throughout the bloodstream are lens-shaped structures that serve to plug the wound.

Search this Function

Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

Search this Living System

Nutrient transport tubes in fava beans and other legumes are plugged quickly when damaged via shape-changing mechano-proteins called forisomes.

“Sieve tubes in legumes contain forisomes, which are spindle-like bodies
that are composed of ATP-independent, mechanically active proteins. Upon
injury, forisomes occlude sieve tubes by dispersion and thus, help to
prevent loss of nutrient-rich transport sap. Forisome enlargement by
dispersion is brought about by Ca2+-induced conformational changes that
confer radial expansion and longitudinal contraction. Forisomes
recontract upon Ca2+ removal. In vitro, forisomes reversibly disperse
and contract in the presence or absence of Ca2+, respectively, and at
distinct pHs. Recently, forisomes have received renewed attention
because of their unique capacity to convert chemical into mechanical
energy independent of high-energy organic compounds. Forisome-based
‘smart’ materials can be used to produce self-powered monitoring and
diagnostic systems.” (Tuteja et al. 2010:102)

http://jxb.oxfordjournals.org/cgi/content/abstract/57/12/3091
http://www.pnas.org/content/104/25/10536
http://www.ncbi.nlm.nih.gov/pubmed/20004992

Last Updated August 18, 2016

References

Journal article

Forisomes: calcium-powered protein complexes with potential as ‘smart’ biomaterials

Trends in Biotechnology | 12/12/2009 | Narendra Tuteja, Pavan Umate, Aart J.E. van Bel

embedly preview

Reference

Journal article

The geometry of the forisome-sieve element-sieve plate complex in the phloem of Vicia faba L. leaflets

Journal of Experimental Botany | 02/08/2006 | W. S. Peters

embedly preview

Reference

Journal article

Molecular sabotage of plant defense by aphid saliva

Proceedings of the National Academy of Sciences | 07/06/2007 | T. Will, W. F. Tjallingii, A. Thonnessen, A. J. E. van Bel

embedly preview

AskNature