Swine chromosomal DNA quantification by bivariate flow karyotyping and karyotype interpretation

Abstract

Human and swine chromosomes were analyzed separately and as a mix to obtain bivariate flow karyotypes. They were normalized to each other in order to use the human chromosomal DNA content as standard. Our results led to the characterization of the "DNA line" in swine identical to the human "DNA line." Estimation of the DNA content in megabase pairs of the swine chromosomes is proposed. Chromosomal assignment to the various resolved peaks on the bivariate swine flow karyotype is suggested from the relation between DNA content quantified by flow cytometry and chromosomal size. Swine chromosomes 1,13, 6,5,10,16,11,18, and Y were assigned to peaks A, B, C, K, L, N, 0, Q, and Y, respectively. Peaks D and E were assumed to contain chromosomes 2 and 14, but without specific assignment. Similarly, P and M peaks were expected to correspond to chromosomes 12 and 17. Of the remaining chromosomes (3, 7, X, 8, 15, 9, and 4), chromosomes 3, 7, and X, which were assigned previously to peaks F, G, and H, respectively, led us to deduce that chromosomes 15 and 8 belonged to peaks I and J, and chromosomes 9,4, and X to peak H. CI 1992 Wiley-Liss, Inc.Key terms: DNA line, chromosome identification Flow cytogenetic techniques already contribute greatly to our knowledge of the genome in mammals. They have, for instance, proved invaluable in detecting numeral and structural aberrations associated with human genetic diseases. They have also been extensively applied to human chromosome sorting, thereby permitting the construction of chromosome-specific DNA libraries (see ref. 6 for review). Applied to domestic species, flow cytometric techniques have been particularly straightforward in swine cytogenetic analyses, as most of the chromosomes in this species are both fairly different in size, and are fewer in number compared with human or bovine chromosomes (22).Flow cytogenetics and chromosome sorting therefore appear especially relevant for the ongoing European PiGMaP project (2). Among the aims of the project is the construction of chromosome-specific libraries, in order to provide as quickly as possible chromosome-assigned markers, which in conjunction with other techniques will allow coverage of the whole genome. A prerequisite to production of chromosome-specific libraries is accurate assignment of all, or at least most, of the swine chromosomes to the peaks of the flow karyotype and the estimation of the swine chromosomal DNA content. We therefore further developed studies on bivariate flow karyotypes in swine, as previous results showed that good chromosome resolution was easily achievable (7,s). All swine chromosome types could be resolved into individual peaks except two autosomal pairs plus chromosome X, which were confounded (15).The work reported here concerns the establishment of a "DNA line" in swine, a technique successfully applied to human chromosomes (17,3,18 somes to the various peaks on the bivariate flow karyotype. MATERIALS AND METHODSAnimals We analyzed the karyotypes of 11 pigs of both sexes, 9 males and 2 females...

Cytogenetic assignment of 53 microsatellites from the USDA-MARC porcine genetic map

“…However, SSC 11q1.7, 14q1.1, and 18q1.1 still appear to lack genetic and physically assigned markers. These three regions represent a total of approximately 36.5 Mb, or 1.3 % of the porcine genome based on the standard karyotype and chromosome size reported by Schmitz et al (1992).…”

A comprehensive map of the porcine genome.

“…Because telomeric regions of chromosomes are more recombinationally active than centromeric regions in man (Tanzi et al 1992;Matise et al 1994;Zahn and Kwiatkowski 1995) and the same trend is present in this map, the size of the porcine genome is likely to be closer to the 2300 cM reported by Rohrer et al (1994b). (Schmitz et al 1992). If we assume chromosomal coverage is complete (see below) and cM/Mbp equal for each chromosome, all estimates would be expected to be similar.…”

Low Frequency of Microsatellites in the Avian Genome

“…The amount of genomic DNA used on dot-blot filters was calculated taking into account the differing genome sizes so that the quantity of DNA used for each species contained approximately the same number of genome copies (equimolar amounts). Starting from 300 ng of human DNA (assuming a genome size of 3.0 ‫ן‬ 10 9 bp), 280 ng of pig DNA (2.8 ‫ן‬ 10 9 bp; Schmitz et al 1992) and 120 ng of DNA of the three avian species (1.2 ‫ן‬ 10 9 bp; Bloom et al 1993), serial dilutions of 50%, 25%, and 12.5% were also analyzed to minimize potential experimental biases (cf. Anchordoguy et al 1996).…”