Robertsonian metacentrics in the mouse

Abstract

A survey is given on the occurrence, the geographic origin and the arm composition of 27 Robertsonian fusion metacentric chromosomes of wild populations of the mouse. Their study is of twofold interest: a) it is possible to introduce these naturally occuring metacentrics in laboratory strains for experimental use. At present, altogether 34 metacentric chromosomes of different composition are available including 7 cases of metacentrics known form laboratory strains of the mouse. b) With the search for metacentrics in the mouse and with their identification insights are permitted in the role of Robertsonian changes in the course of mammalian evolution--Several separate populations of the mouse with different sets of multiple (up to 9) metacentrics have been found in Switzerland and Italy. Some of the individual metacentrics may occur in different populations. The participation of an acrocentric autosome in the formation of metacentrics seem to be at random, but the sex chromosomes are never included in a metacentric.--Homology of the arms involved in metacentrics is conserved, so that in meiosis of interpopulation hybrids is due to mechanisms of segregational imbalance and subsequent prenatal elimination of fetal offspring, but it follows also the pattern of male limited hybrid sterility.--From an evolutionary view point, karyotype rearrangements of Robertsonian type may initiate reproductive isolation, which prepares the ground for further genetic diversification and, as in the case of the mouse, of incipient speciation.

Chromosome number variation in three mouse embryonic stem cell lines during culture

“…Metacentric chromosomes were the most frequent chromosome abnormality observed throughout the period of culture. Proneness of the mouse genome to form metacentric has been described already in several feral house mouse populations (Capanna et al 1976;Redi and Capanna 1988;Britton-Davidian et al 2005) and in culture (Chakrabarti and Chakrabarti 1977).…”

Chromosomes and microevolutionary processes

“…However, such skepticism concerns only the simplex Robertsonian heterozygosity. A different kind of karyotype divergence exists which Capanna et al (1976) singled out in house mice and which we named monobrachial homology, the consequence of which on the reproductive capability of hybrids is significant indeed (Redi & Capanna, 1988).…”

Chromosomal mapping of the structural gene coding for the mouse cell adhesion molecule uvomorulin.

“…So far, this method has been used in the chromosomal mapping of the mouse genes coding for myosin heavy chain, myosin light chain, muscle nicotinic acetylcholine receptor, interferon , and others, such as several homeobox-containing genes (15)(16)(17)(18)(19). Second, the chromosomal location of the uvomorulin gene was studied by in situ hybridization of uvomorulin cDNA to metaphase chromosomes of fibroblasts from mouse strain CD (20). These cells contain nine pair of wellcharacterized morphologically distinguishable metacentric chromosomes (leaving acrocentric chromosome 19 and the sex chromosomes Y and X), which facilitates the unambiguous karyotyping.…”