Bernard Ogilvie Dodge - Neurospora Research

Neurospora Research

As a graduate student and instructor at Columbia University, Dodge investigated the taxonomy and reproduction of species of Ascobolaceae. He found that the ascospores of several species of Ascobolus which rarely germinate under ordinary conditions on artificial media, do so readily after being subjected to 50-70 degrees Celsius for five to 10 minutes. Dodge discovered this completely by accident: after trying several methods to germinate the ascospores of Ascobolus (without success), one day Dodge temporarily set down a batch of test plates inside a hot-air sterilizer which was not running, while he went to teach a class. When Dodge returned he was dismayed to find that someone had lit the oven in the interim, and the temperature inside had reached over 70 degrees. Dodge removed the plates, assumed that the spores had been killed, but before discarding the old plates he examined them under a microscope. He was astounded to find that most of the spores had germinated. This discovery proved to be of importance later for his studies of Neurospora.

Though Dodge considered himself primarily a mycologist and a plant pathologist, his study of Neurospora is regarded by many as his major work. As he told W. J. Robbins:

I was, 1925-6, highly interested in studies on the blackberry rusts, short and long cycle forms (species). I had foud that I could pass the rust on the Black Diamond blackberry (dewberry) by grafting to young shoots of this species, and was trying to culture the rest on cornmeal agar in plates and flasks. So I had several plates and flasks (250 cc) standing on shelves in the Arlington Farm greenhouses. I was much concerned to find that Monila sitophila had gotten into some of the flasks as well as some plates. Practically all of them were soon bearing perithecia resembling those Dr. C. L. Shear had shown me and asked me to try to germinate the ascospores. I was so much excited and interested in my rust studies that I could not leave those experiments to help my superior out. I did suggest trying to make those spores germinate by heating them. Several weeks had passed when this red bread mold developed in my greenhouse flasks and plates. Just on a chance I inverted plates of corn agar on cultures of perithecia shooting spores so spores were shot upward and scattered about. I put some of these plates in a drying oven and heated them as I had gone many times to make ascospores of Ascobolus to germinate. By next morning a high percentage of the mold had germinated.

The ability to germinate the ascospores of Neurospora made it possible to define its life cycle, distinguish species, make crosses between species, and grow the haploid offspring.

Over the next 30 years, Dodge published over 40 papers on Neurospora, which was easy to grow and required little space (and only a few days) to complete its life cycle. These advantages made Neurospora, in many respects, an ideal organism for the investigation of genetics and biochemical genetics. Dodge convinced Thomas Hunt Morgan of the advantages of Neurospora and Morgan took cultures with him when he transferred from Columbia University to the California Institute of Technology in 1928.