NON-DISJUNCTION OF THE X-CHROMOSOME IN DROSOPHILA VIRILIS

M. Demerec, J. G. Farrow
1930 Proceedings of the National Academy of Sciences of the United States of America  
The difference in the molecular rotations of cellobiose and 4-glucosido-gmannose is approximately 7200. This value is in agreement with Hudson's classification, or in other words, with the value obtained from l-jmannose and normal glucose. Thus it appears that 4-glucosido-a-mannose is a substituted a-mannose, while 4-glucosido-,3-mannose is a substituted ,3mannose. The rotations of the alpha forms give an epimeric difference of about 16,900, while those of the beta give a difference of about
more » ... 0. The parallelism between the optical rotations of the a-and d-forms of 4-glucosido-mannose with the corresponding forms of mannose indicates that neither a-nor P-mannose has a 1,4 ring structure. We cannot definitely state at this time which form of mannose has a structure similar to the normal form of glucose. It is entirely possible that Hudson's classification of ring structures is in reality a classification of a new type of isomerism. It seems reasonable to presume that there is a difference in the structures of a-and P-mannose, the exact nature of which must remain for the future to determine. The writer expresses his appreciation to Dr. D. H. Brauns for the loan of the apparatus with which he originally prepared 4-glucosido-a-mannose. Appreciation is also expressed to other members of the Polarimetry Section who have aided in the course of the investigation. An extensive series of experiments were made to test the effect of x-ray radiation on the mutability of the mutable reddish-alpha and the miniaturebeta genes. These experiments were planned in, such a way as to give results which could be used to determine the effect of x-rays on the mutable genes and also to study non-disjunction of the X-chromosome. The results related to the problem mentioned last will be reported in this paper. PRIMARY NON-DISJUNCTIONS. Frequency.-Data on the frequency of primary non-disjunctions were obtained by breeding F1 females from crosses involving several sex-linked characters. That precaution made it certain that these females were not non-disjunctional and to a large extent eliminated the possibility of inclusion in the results of secondary non-disjunctions. Since, however, there was practically no way of making certain that the male parents of the F1 females were not XYY, it cannot be claimed VOL. 16, 1930 707
doi:10.1073/pnas.16.11.707 pmid:16577296 pmcid:PMC526721 fatcat:pvtqe7kldbebtamqpga76b2mue