Telling ring from left – more to it than meets the eye (or – how to teach pigeons to read)
✍ Scribed by Adam S. Wilkins
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 303 KB
- Volume
- 13
- Category
- Article
- ISSN
- 0265-9247
No coin nor oath required. For personal study only.
✦ Synopsis
A common perception and belief about bilateral animals is that they are left-right (L-R) symmetric. In fact, this symmetry is often far from perfect. More surprisingly, there are reproducible handed asymmetries in bilateral animals, involving such aspects, for instance, as the dextral looping of the heart in mammals. What are the ultimate sources of handed asymmetries and what are their consequences, including behavioural ones? It was to grapple with these questions that a Ciba Foundation Symposium, 'Biological Asymmetry and Handedness'. was held in London, from the 19th to the 22nd of February*. The meeting was organized by Dr Nigel Brown (MRC Unit. St. George's Hospital Medical School, London), in collaboration with the Ciba Foundation, and chaired by Prof. Lewis Wolpcrt (Middlesex Hospital School of Medicine, London). The central task of the meeting, as noted by Prof. Wolpert in his opening remarks, was to explore the nature of the connections between asymmetry at the molecular level and higher order forms of handedness. As he phrased the issue: 'If, in the early history of life, D-rather than L-amino acids had been used to construct proteins, would our hearts be on the right, not the left, side of our bodies?' The meeting began, unusually, with the immediate disproof of a hypothesis, that of the chairman (himself a lefthander), that people interested in the topic of handedncss might be disproportionately left-handers; a quick poll reviewed the percentage of left-handers in the conference to bc that of the population at large (about 10 %).
The first full day of the meeting was devoted to handedness in molecules. the second day to left-right asymmetries in embryonic development, and the third, and final day. to the significance of left-right differences in brain development and construction. The progression was, in effect. from the best understood subjects to the least understood.
Although the basis of molecular handedness is considerably clearer than L-R brain differences, the first talk by S. Mason (University of Cambridge) dealt with a molecular mystery, the fact that while standard inorganic syntheses of amino acids and sugars produce equal amounts of L-and D-forms (racemic mixtures). terrestrial life forms use only L-based amino acids and *The proceedings are to be published. The volume, Biological Asymmetry mid Hartdedriess (ed. J. Marsh