Tracy Sonneborn
Encyclopedia
Tracy Morton Sonneborn was an American
biologist. His life's study was of the protozoa
n group Paramecium.
's cilia. These minuscule hair-like projections enable the cell to 'swim'. They move together and paddle the cell through the water in which it lives.
The paramecium
is a single-cell organism, so has nothing remotely resembling a brain. Yet its cilia move together like dancers in a ballet. How is it that their movements are co-ordinated?
Sonneborn surgically removed a small section of cell wall and replaced it rotated by 180 degrees. The cilia in the replaced section continued to 'wave' in the same direction as they had before surgery, i.e. now in antiphase to the others. What was remarkable is that both daughters of paramecia on which this operation had been performed also showed the same trait of a reverse phase wave in a similar area of their cell wall, as did, to a lesser extent, the granddaughter cells.
It is a mark of his excellence as a scientist that he should have taken the trouble to follow the fate of subsequent generations and so be able to make this observation. It may seem surprising that the clear evidence for non-Mendelian inheritance should have been largely overlooked by the scientific community. Further research was at that time limited because the available staining techniques to allow electron microscopy denatured the microtubules which 'power' the cilia so their presence in cells could not be seen. It may also be that, as at that time the mechanisms of genetic inheritance in DNA were becoming open to investigation, this example of non-Mendelian inheritance was not of great interest to the scientific community.
to Bloomington
.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
biologist. His life's study was of the protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
n group Paramecium.
Non-Mendelian Inheritance
In the late 1950s he conducted an elegant series of experiments in his endeavours to discover what it is that mediates the synchronised movement of the parameciumParamecium
Paramecium is a group of unicellular ciliate protozoa, which are commonly studied as a representative of the ciliate group, and range from about 0.05 to 0.35 mm in length. Simple cilia cover the body, which allow the cell to move with a synchronous motion at speeds of approximately 12 body...
's cilia. These minuscule hair-like projections enable the cell to 'swim'. They move together and paddle the cell through the water in which it lives.
The paramecium
Paramecium
Paramecium is a group of unicellular ciliate protozoa, which are commonly studied as a representative of the ciliate group, and range from about 0.05 to 0.35 mm in length. Simple cilia cover the body, which allow the cell to move with a synchronous motion at speeds of approximately 12 body...
is a single-cell organism, so has nothing remotely resembling a brain. Yet its cilia move together like dancers in a ballet. How is it that their movements are co-ordinated?
Sonneborn surgically removed a small section of cell wall and replaced it rotated by 180 degrees. The cilia in the replaced section continued to 'wave' in the same direction as they had before surgery, i.e. now in antiphase to the others. What was remarkable is that both daughters of paramecia on which this operation had been performed also showed the same trait of a reverse phase wave in a similar area of their cell wall, as did, to a lesser extent, the granddaughter cells.
It is a mark of his excellence as a scientist that he should have taken the trouble to follow the fate of subsequent generations and so be able to make this observation. It may seem surprising that the clear evidence for non-Mendelian inheritance should have been largely overlooked by the scientific community. Further research was at that time limited because the available staining techniques to allow electron microscopy denatured the microtubules which 'power' the cilia so their presence in cells could not be seen. It may also be that, as at that time the mechanisms of genetic inheritance in DNA were becoming open to investigation, this example of non-Mendelian inheritance was not of great interest to the scientific community.
Sonneborn as teacher
Sonneborn is remembered by his students for an amusing lecture, illustrated with chalkboard drawings, that he gave each year before Christmas break in which he described evolution in terms of a journey from IndianapolisIndianapolis, Indiana
Indianapolis is the capital of the U.S. state of Indiana, and the county seat of Marion County, Indiana. As of the 2010 United States Census, the city's population is 839,489. It is by far Indiana's largest city and, as of the 2010 U.S...
to Bloomington
Bloomington, Indiana
Bloomington is a city in and the county seat of Monroe County in the southern region of the U.S. state of Indiana. The population was 80,405 at the 2010 census....
.
External links
- Sonneborn Manuscripts at the Lilly Library Manuscript Collections