Procedures for Culturing Diploid Cells and Preparation of Meiotic Chromosomes from Dwarf Species of Hamsters

Abstract

Among the 12 species and subspecies of dwarf hamsters that comprise the genus CricetultiSy only three have been domesticated to serve as laboratory specimens: the Chinese hamster (2n = 22), C. griseus; the Armenian hamster (2n = 22), C. migratorius; and the Dzungarian hamster (2n = 28), Phodopus songorus (Yerganian, 1958; Yerganian and Papoyan, 1965; Pogosianz and Sokova, 1967). The contents of this chapter apply specifically to the cell and animal systems of the two former species, as developed and applied in this laboratory to assess mutagenic and carcinogenic properties of chemical and viral agents. With inbreeding advanced to the thirty-fifth generation of brother-sister matings, corresponding in vitro and in vivo studies are now being conducted, for the first time in 20 years, using near-isogenic, histocompatible animals and derived cell lines. The latter achievement has also been supplemented by the formulation of growth media which encourage normal, malignant, and virus-transformed cells to retain their original (diploid) karyotype and proliferate indefinitely at optimal rates. Together, these more recent developments provide the desired genetic uniformity for our current molecular approaches to establish basic levels of biochemical parameters peculiar to diploid cell lines differing in experimental backgrounds. In the absence of secondary, unrelated aneuploidy among the different cell lines, and availability of the parent diploid control cell lines, genetic uniformity prevails throughout the cell system(s) and unrelated physiological attributes associated with secondary aneuploidy per se pose no immediate problems.

Support of research employing the techniques described has been provided by the National Science Foundation (GB-7458), Damon Runyon Memorial Fund (# 293), and the National Institutes of Health, USPHS (CA-08378 and CA-6516).