Section 16 — Human Cytogenetics 



hypotetraploid populations and increases in the 

 "diploid" populations. The abnormal, bi-armed 

 chromosomes were apparently preferentially 

 involved. 



Development Award (PCI 1-63) from The Na- 

 tional Institutes of Health. 



Support by CCNSC Contract SA-43-ph-2445. 



16.37. (D.). Some Relationships of Viruses and 

 Chromosomes. Warren W. Nichols, Albert 

 Levan, Rei Kato, and C. G. Ahlstrom 

 (Lund, Sweden). 



In a long-term study of the relationships of 

 viruses chromosomes and carcinogenesis, two 

 model systems, Rous sarcoma in the rat and 

 measles, have been utilized. The Rous sarcoma 

 system has been studied from the aspects of 

 zero passage and serially transplanted tumors, 

 both in vivo and in vitro, and by the addition of 

 the virus to normal cells in tissue culture. Both 

 in vivo and in vitro, the tumor has shown a pro- 

 gression of chromosomal changes with initially 

 normal karyotypes, or karyotypes with changes 

 in the number of chromosomes around the di- 

 ploid level, followed by changes in chromosome 

 type, and finally changes in ploidy. The addition 

 of Rous sarcoma virus to normal rat cells in 

 tissue culture produced an increased incidence 

 of chromosome breakage and abnormalities 

 over the control level. 



In the measles system, clinical measles was 

 found to be associated with chromosome break- 

 age in the white blood cells. When patients were 

 studied who received live attenuated measles 

 vaccine, breakage was again found but to a 

 lesser extent than in the disease, and there were 

 indications that natural immunity or injection of 

 gamma globulin at the time of immunization 

 offered some protection against the breakage 

 phenomenon. 



Chromosome breakage fits well into a somatic 

 mutation theory of carcinogenesis and it is in- 

 teresting that chromosome breakage is a com- 

 mon denomination in the three classes of material 

 that are known to be carcinogens; namely, irra- 

 diation, chemicals and viruses. 



This work has been supported in part by 

 grants-in-aid from The National Institute of 

 Health (C4953 and C43845 and CA06415) and 

 The American Cancer Society (ElllB), The Swed- 

 ish Cancer Society (62:80), The Swedish Med- 

 ical and Natural Sciences Research Councils 

 (U212 and T432) and by a Research Career 



16.38. Chromosomal Aberrations Associated with 

 Virus Infections in Man. Ulla Gripenberg 

 (Helsinki, Finland). 



Leucocyte cultures have been raised at the 

 acute stage of several different infections (1-20 

 days after getting sick). About 100 karyotypes of 

 each culture have been examined in order to 

 determine the frequency and localization of 

 chromosome breakages. Chromosome prepara- 

 tions have been made from 1-5 patients with each 

 of the following infections: morbilli, exanthema 

 subitum, epidemic parotitis, varicella, infectious 

 mononucleosis, mesenteric lymphadenitis. 



An increased incidence of various chromoso- 

 mal aberrations was found in the different 

 cases. (The final percentage of cells with aberra- 

 tions, as well as the nature and localization of 

 these will be reported later.) 



16.39. Approach to the Cytogenetics of Mammalian 

 Cells cultured in Vitro. L. De Carli, J. J. 

 Maio and F. Nuzzo (Pavia, Italy). 



Mammalian cells in tissue culture may yet 

 offer the best approach toward initiating true 

 cytogenetic studies which could correlate the 

 data obtained from chromosomal analyses with 

 variations in cellular phenotypes. The possibility 

 would then be offered of locating cytologically 

 the genetic control of some cellular characters 

 recognizable in vitro. Although variants may be 

 easily isolated from the heteroploid cell strains, 

 this material is poorly adapted or even useless 

 for many experiments of genetic analysis. How- 

 ever, these same strains could be even preferable 

 to euploid cultures in some instances if one 

 would study the correlation between chromoso- 

 mal variations and the phenotypic changes in a 

 given character. In fact, the chromosomal varia- 

 bility of heteroploid strains can be usefully 

 exploited since it may give rise to a series of 

 polysomic states for some chromosomes which 

 may correspond to a gradient of expression in 

 the cellular phenotype. Furthermore, particular 

 chromosomal patterns may be stabilized for a 

 sufficient number of cell generations by means 

 of clonal procedures. 



As an example of this approach to the cyto- 

 genetics of mammalian cells cultured in vitro, 

 data are presented concerning the karyotypic 

 analyses of several clonal lines derived from a 



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