1942: Biology

Dr. H. A. Allard of the Bureau of Plant Industry, U. S. Department of Agriculture, reports that a portion of the original tobacco mosaic virus extracted in 1914 was found to retain its infectivity for at least twenty-eight years in vitro under certain conditions. This virus was found, upon testing, to be only slightly acid. The author suggests that this is the reason for its highly infectious nature. Other samples of virus preserved the same way have become entirely innocuous and these were found to have become highly acid in their reaction thus resulting, he claims, in the loss in infectivity.

Dr. Folke Johnson, Department of Botany, Ohio State University, has investigated the resistance of wheat mosaic virus Marmor tritici H. in the soil to heat. He has very carefully controlled his experiments and has found that wheat plants grown in virus-infested soil heated at 40° and 50° C. were affected with mosaic, while all plants in all series heated above this temperature remained healthy. This indicates that this wheat mosaic virus is inactivated in the soil between 50° and 60° C., at an exposure of ten minutes.

Drs. T. P. Dykstra and H. G. Du Buy of the Bureau of Plant Industry, U. S. Department of Agriculture and the University of Maryland, have carried out a series of experiments in an attempt to devise some method of treating plant virus so that their virulence could be retained for a considerable length of time. Their experiments indicate that oxidation had an indirect effect upon the destruction of the virus. Additional information on this problem is still in progress.

It has been known for some time that certain bacteria can be killed by substances secreted by other bacteria but Dr. W. N. Takahashi, of the University of California, is probably the first investigator to show that a substance exists in yeast which destroys the toxicity of a plant-mosaic virus. Chemical analysis of this new virus inhibitor has not been thoroughly investigated but indications are that it may possibly be a polysaccharide or complex sugar.

Dr. Harry Plotz and Reginald Reagan of the Army Medical School, Washington, D. C., are the first to cultivate directly in vitro the street virus of rabies. Two strains were developed, one directly from the brain of a human case of rabies and the other from the brain of a rabid dog. A new method of culture was employed and experiments are now under way to determine whether these cultures can be employed as a vaccine.

Dr. George L. McNew of the New York State Agricultural Experiment Station reports that a new chemical, tetrachloro-parabenzoquinone, has been developed which combats a disease-causing fungus affecting fresh sown peas. While this synthetic chemical is stated to be the first strictly organic, nonmetallic compound to show considerable promise as a plant protectant against fungus diseases, it is also of interest to find, by experiments, that it acts as a good growth-and-yield stimulant as well.

Pyridoxine (vitamin B₆) has been found to be necessary for the growth of cultures of Graphium ulmi, the organism which causes Dutch elm disease as reported by investigators at the Osborn Botanical Laboratory of Yale University. This is one of the few cases where it has been shown that an accessory growth factor is necessary for the life of a parasitic fungus. In this instance the discovery may be of use to phytopathologists in the attempt to control the Dutch elm disease.

Dr. D. G. Langham of the Instituto Experimental De Agricultura y Cria, El Valle, Caracas, Venezuela, reports that the sesame plant or Sesamum indicum, a plant which has been cultivated since ancient times for the high quality of oil in its seeds, has been so modified by experimental developmental procedures that new strains have been developed which have fifty per cent larger seeds without any reduction in the number of seeds found in the ancestral varieties. The standard strains were treated with Colchicine to bring about these changes. To date, no field tests of the comparative seed yields or the per cent of oil of the various strains have been completed.

Dr. H. J. Humm of the Duke University Marine Laboratory, Beaufort, North Carolina, reports that a systematic test of all the more common larger species of red algae of the Atlantic coast from Beaufort to the Florida Keys is being undertaken with the purpose of finding a suitable substitute for agar. This substance is used in bacteriology, medicine, and in certain industries, and it is of utmost importance that a substitute be found to replace the lost Japanese import source of agar. To date several red algae species have been found to yield fairly large quantities of agar.

Dr. H. S. Burr of the Anatomy Department of Yale University has previously measured electrical potentials in animals. These experiments have recently been tried on growing corn plants and he has found that the variations in electrical potentials correspond very accurately with changes in the rate of growth and with internal structural developments.

Clinical studies have been continued the past year on a comparatively new synthetic pain-relieving drug known as Demerol. This substance was first developed in Germany but is now being made in the United States and experiments are being conducted to see whether it will serve as a safe substitute for morphine.

Workers at the Radiation Laboratory of the University of California have carried out some interesting studies in cytology during the past year. Heretofore, one of the stages of cell-division known as the resting stages was considered to be one of relative inactivity. However, with the aid of the atom-smashing cyclotron it was found that those cells in the so-called resting stage were damaged considerably more at one period than at other periods of the same stage. This suggests physiological activity rather than inactivity.

Dr. E. F. Gomez, of the U. S. Department of Agriculture, has reported the finding of a substance in plants which is reported to strongly stimulate sexual maturation in female animals. Extracts from freshly cut or frozen young oat and corn plants, when fed to rats, were found to shorten the period previous to sexual maturity by at least eight days. What these plant extracts consist of has not been definitely determined as yet.

Investigators in the biological laboratories of the Catholic University of America have succeeded in modifying the chromosome numbers in cells of certain limited parts of the nervous system of the common fruit-fly by the injection of Colchicine. Heretofore, experiments with Colchicine have produced surprising results in plant breeding and it is possible that similar results may eventually be brought forth in the animal kingdom.

Dr. J. R. Borland of Hofstra College and New York University has accelerated the metamorphosis or transformation process of the tadpole into the frog by feeding substances rich in cyanide compounds and also by feeding dilute solutions of methyl cyanide to these animals.

Dr. R. D. Manwell of the Biology Department, Syracuse University reports that germs of bird malaria and possibly germs of other diseases as well, can be frozen at a temperature of 100° F. below zero, and maintained at that temperature for a period of seven weeks without damages. Rapid thawing is necessary he states, to avoid killing the germs. The above procedure would be of importance in transportation of these germs for experimental tests.