title: Induction of pigmentation by continuous X-irradiation of amelanotic tumors of B16-XI mouse melanoma and induced change in chromosomes of amelanotic cells.
abstract: Non-pigmented tumor cells of B16-XI mouse melanoma were found to contain a diploid number of chromosomes similarly to those of melanotic tumors and the parental cells in tissue culture. A major difference between pigmented and non-pigmented cells was in the number of biarmed chromosomes per cell. There was no difference in growth rate between non-pigmented and pigmented tumors, but growth usually begins about 2 days earlier in the former. Pigmentation lost in the course of serial transplantation was restored by irradiating the non-pigmented tumor continuously with 2,500-3,000 rads/passage of X-rays during six transfer generations. In the course of repeated irradiations, the chromosomes changed structurally and numerically as the pigmentation of the tumor was gradually restored. The observations of tumor growth and chromosomal changes are discussed in relation to the pigmentation of B16-XI melanoma cells.
mesh_terms: D000818:Animals; D002875:Chromosomes / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D008543:Melanins / Q000096:biosynthesis* / Q000235:genetics; D008544:Melanocytes / Q000378:metabolism / Q000528:radiation effects*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism; D010858:Pigmentation / Q000528:radiation effects*
chemical_list: D008543:Melanins