Identification of the Mouse Karyotype by Quinacrine Fluorescence, and Tentative Assignment of Seven Linkage Groups

Abstract

A karyotype of the mitotic chromosomes of the house mouse has been prepared based upon quinacrine fluorescence patterns. All 19 pairs of autosomes and the X and Y chromosomes have been identified. Examination of the chromosomes of the following translocation stocks, T(11;?)lAld, T(3;?)6Ca, T(2;9)138Ca, T(2;12)163H, and T(9;13)19OCa, have led to the tentative assignments of autosomal linkage groups (LG) Meiotic studies of the house mouse, Mus musculus, have been very informative (1), but mitotic studies have been restricted by the limited variation in morphology of the chromosomes, all of which are acrocentric with small gradations in length. The only translocations that could be detected in stained preparations of mitotic chromosomes involved a marked change in length, such as the presence of a minute chromosome in the T6 (2) and one very long and one very short chromosome in the T190 (3), or the formation of a metacentric chromosome, as in the T163 (4). Bennett (3), who gives a brief review of prior cytologic studies, used the secondary constrictions in several chromosomes to help divide the complement into pairs. She was unable to detect any abnormality in T138.It was recently reported that quinacrine and quinacrine mustard are bound to the DNA of human chromosomes in such a highly specific manner that each chromosome can be identified by its pattern of quinacrine fluorescence (5). Furthermore, the fluorescence patterns of chromosomal segments do not appear to be altered by translocation (6).The accuracy of the quinacrine fluorescence technique of chromosome identification, and the availability of numerous potentially overlapping translocations in the house mouse, suggested to us the possibility of assigning the known murine linkage groups (LG) involved in these translocations to their specific chromosomes. MATERIALS AND METHODSStandard inbred and hybrid mice were purchased from The Jackson Laboratory, as were translocation stocks T(3;?)6Ca and T(2;9)138Ca. Translocation stocks T(2;12)163H,T(11;?)-lAld, and T(9;13)19OCa were obtained from the M.R.C. Primary tissue cultures were established from mice by trypsinization of 11-to 13-day embryos in saline-citrate to obtain suspensions of single cells (10). Cells were grown in HEPES-buffered Nutrient Mixture containing 10% calf serum and 5% fetal calf serum. Falcon tissue-culture flasks (75 cm2) were used and each flask was seeded with 10-12 ml of a suspension containing 5 X 105 viable cells/ml. After 2 or 3 days at 370C, cells (including a large proportion in metaphase) were collected by washing the cell surface twice with calcium-and magnesium-free phosphate-buffered saline, followed by a 5-min treatment of the surface with 3 ml per flask of 0.25% Viokase. Cells from 5-7 flasks were pooled, and Colcemid was added to a final concentration of 0.5 ,g/ml. Cells were immediately pelleted by centrifugation at 500 g for 10 min, resuspended in 10 ml of 0.032 M KCl, and incubated at 37°C for 5 min. 0.5 ml of freshly prepared fixative (methyl alcohol-glacial acet...

Expression of human and suppression of mouse nucleolus organizer activity in mouse-human somatic cell hybrids.

“…In most of the cells it is clear that no mouse NORs are stained by the Ag-AS method. This is not due to the loss of the mouse chromosomes that carry the structural genes for rRNA (numbers 12,15,18, and sometimes 16 in BALB/c) because chromosomes 15 and 18 are present in high frequency in the hybrids (55-14 and 55-44) that were derived from BALB/c. Furthermore, it is unlikely to be due to the loss of a specific mouse chromosome that does not have an NOR because hybrid 55-84 has copies of every mouse chromosome.…”

“…The BALB/c peritoneal macrophage X HT-1080-6TG hybrid 55-14, for example, has a mean of 76 (range 61-87) human and 18 (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) mouse chromosomes. Copies of every human chromosome are present (Fig.…”

“…After 10 min the suspension was centrifuged and the cells were fixed for an hour in freshly prepared 3:1 methanol:acetic acid. After two changes of fixative the cells were dropped onto cold wet slides, which were allowed to air dry.Quinacrine staining was done by the method described by Miller et al (18). Well-spread metaphases were photographed on H & W Control film.…”

“…Quinacrine staining was done by the method described by Miller et al (18). Well-spread metaphases were photographed on H & W Control film.…”

Karyotypic analysis of two L1210 murine leukemia lines growing in vivo and in vitro.

“…Some investigators have found difficulty in distinguishing chromosome 9 from 13 (Miller, Miller, Kouri, Allderdiee, Dev, Grewal andHutton 1971, Comittee 1972). Although there is no doubt that one of the arms of metacentric chro mosome denoted as marker M5 consists of chromosome 9, however we can not exclude a possibility that part of chromosomes of pair 13 was erroneously classi fied as chromosomes of pair 9.…”