D. S. Gallagher

Standardization of cattle karyotype nomenclature: Report of the committee for the standardization of the cattle karyotype

The purpose of this paper is to publish a table which correlates the previous nomenclature with marker genes mapped on cattle chromosomes. This table also presents the human correspondences and the chromosome measurements expressed as relative lengths.

Evolutionary histories of highly repeated DNA families among the Artiodactyla (Mammalia).

Six highly repeated DNA families were analyzed using Southern blotting and fluorescence in situ hybridization in a comparative study of 46 species of artiodactyls belonging to seven of the eight extant taxonomic families. Two of the repeats, the dispersed bovine-Pst family and the localized 1.715 component, were found to have the broadest taxonomic distributions, being present in all pecoran ruminants (Giraffidae, Cervidae, Antilocapridae, and Bovidae), indicating that these repeats may be 25–40 million years old. Different 1.715 restriction patterns were observed in different taxonomic families, indicating that independent concerted evolution events have homogenized different motifs in different lineages. The other four satellite arrays were restricted to the Bovini and sometimes to the related Boselaphini and Tragelaphini. Results reveal that among the two compound satellites studied, the two components of the 1.711 a originated simultaneously, whereas the two components of the 1.711b originated at two different historical times, perhaps as many as 15 million years apart. Systematic conclusions support the monophyly of the infraorder Pecora, the monophyly of the subfamily Bovinae (containing the Boselaphini, Bovini, and Tragelaphini), an inability to resolve any interrelationships among the other tribes of bovids, paraphyly of the genusBos with respect toBison, and a lack of molecular variation among two morphologically and ecologically distinct subspecies of African buffaloes (Syncerus caffer cafer andS. c. nanus). Cytogenetically, a reduction in diploid chromosome numbers through centric fusion in derived karyotypes is accompanied by a loss of centromeric satellite DNA. The nilgai karyotype contains an apparent dicentric chromosome as evidenced by the sites of 1.715 hybridization. Telomeric sequences have been translocated to the centromeres without concomitant chromosomal rearrangement in Thompsons gazelle.

The river buffalo (Bubalus bubalis, 2n = 50) cytogenetic map: assignment of 64 loci by fluorescence in situ hybridization and R-banding

Sixty-four genomic BAC-clones mapping five type I (ADCYAP1, HRH1, IL3, RBP3B and SRY) and 59 type II loci, previously FISH-mapped to goat (63 loci) and cattle (SRY) chromosomes, were fluorescence in situ mapped to river buffalo R-banded chromosomes, noticeably extending the physical map of this species. All mapped loci from 26 bovine syntenic groups were located on homeologous chromosomes and chromosome regions of river buffalo and goat (cattle) chromosomes, confirming the high degree of chromosome homeologies among bovids. Furthermore, an improved cytogenetic map of the river buffalo with 293 loci from all 31 bovine syntenic groups is reported.

Homologies between human and dolphin chromosomes detected by heterologous chromosome painting

Human chromosome-specific probes for the entire karyotype were hybridized to metaphase spreads of the Atlantic bottlenose dolphin, Tursiops truncatus, to directly compare the evolutionary conservation of chromosomal segments between these two distantly related species. All human chromosomal paints, except the Y probe, hybridized to Tursiops counterparts, and every dolphin chromosome was painted except for the smallest submetacentric pair. In our analysis, 36 segments of conserved synteny common to the human and dolphin genomes were identified. The distribution of conserved chromosomal segments and the specific rearrangement patterns found between the two genomes are presented and discussed.

Somatic cell mapping of conglutinin (CGN1) to cattle syntenic group U29 and fluorescence in situ localization to Chromosome 28

A 260-bp genomic PstI fragment, which encodes a portion of the carbohydrate recognition domain, was used along with hybrid somatic cells to map the conglutinin gene (CGN1) to domestic cow (Bos taurus) syntenic group U29. In turn, a cosmid containing the entire bovine CGN1 was used with fluorescence in situ hybridization to sublocalize this gene to cattle chromosome (Chr) (BTA) 28 band 18. Since BTA 28 and several of the other small acrocentric autosomes of cattle are difficult to discriminate, we have also chromosomally sublocalized CGN1 to the p arm of the lone biarmed autosome of the gaur (Bos gaurus). The use of the gaur 2/28 Robertsonian as a marker chromosome and our assignment of CGN1 to BTA 28 should help resolve some of the nomenclatural questions involving this cattle chromosome.

Somatic cell mapping of β-defensin genes to cattle syntenic group U25 and fluorescence in situ localization to Chromosome 27

Antimicrobial peptides have been isolated from a diversity of animal species including insects, lower vertebrates, and mammals (Boman et al. 1994). These peptides are classified into molecular families on the basis of structural features (Boman 1995) and have a proposed role in innate host defense (Zasloff 1992). These peptides exhibit broad-spectrum antimicrobial activity in vitro, owing to their ability to disrupt membranes (Boman 1995). In mammals, two families of cysteine-rich antimicrobial peptides have been recognized. The defensins have been identified in circulating phagocytic cells and in specialized epithelial cells of the small intestine of several species (Lehrer et al. 1993). More recently, a second family of structurally related peptides was discovered. Tracheal antimicrobial peptide (TAP) was the first of these peptides to be isolated and characterized (Diamond et al. 1991) from the bovine tracheal mucosa. Subsequently, 13 additional peptides were isolated from the neutrophils of the cow by Selsted and colleagues (1993), who named this family ~-defensins. Although peptides of both defensins and ~-defensins are similar in size, in vitro antibiotic activity, and structural features, they are clearly distinguish, able by consensus sequences at the gene and protein levels (Bevins 1994; Diamond et al. 1993), and by their disulfide array (Selsted and Harwig 1989; Tang and Selsted 1993). The ~-defensins are encoded by a large family (Diamond et al. 1993). During the isolation of the TAP gene (clone G-3), several additional cross-hybridizing clones were isolated (Diamond et al. 1993). Upon sequence characterization, several of these clones were predicted to encode other ~-defensins. Three of these clones have been further characterized. The clone designated G-I was determined by Northern blot analysis to be expressed exclusively in bone marrow (A. Tarver, G. Diamond, and C.L. Bevins, unpublished observations). Clone G-6 encodes a ~-defensin, BNBD-4 (Yount et al. 1994), found in bovine neutrophils (Selsted et al. 1993), and clone G-11 is expressed in enteric epithelial cells (A. Tarver, G. Diamond, and C.L. Bevins, manuscript in preparation). Sequence similarity among the [3-defensins strongly suggests that this molecular family is derived by duplication of an ancestral gene. To further study the evolutionary history and tissue-specific

Chromosomal localization of omega and trophoblast interferon genes in cattle and river buffalo by sequential R-banding and fluorescent in situ hybridization

Fluorescent in situ hybridization (FISH) of the cattle cDNA probe bTP-509 to RBA-banded cattle (Bos taurus L.) chromosomes confirmed the assignment of the omega (IFNW) and trophoblast (IFNT) interferon genes to chromosome 8q15. Using the same probe, these genes were also localized to river buffalo (Bubalus bubalis L.) chromosome 3q15 following sequential RBA-banding and FISH. The extensive G- and R-banding homology observed between cattle chromosome 8 and river buffalo chromosome arm 3q supports the conserved chromosomal location of the IFNW and IFNT genes in these two species.

High-resolution FISH mapping of β-defensin genes to river buffalo and sheep chromosomes suggests a chromosome discrepancy in cattle standard karyotypes

High-resolution chromosomal fluorescence in situ hybridization (FISH) and R-banding allowed the chromosomal localization of the beta-defensin gene cluster (DEFB@) to chromosome band 1p12 in the river buffalo (Bubalus bubalis, 2n = 50) and to band 24q13 in sheep (Ovis aries, 2n = 54), according to standard nomenclatures. The localizations permitted the tentative assignment of the entire bovine syntenic group U25 to these chromosomes. A FISH mapping control on cattle chromosomes confirmed the localization of DEFB@ in the homoeologous chromosome and chromosome band. Comparisons were made between river buffalo chromosome 1p and the homoeologous cattle chromosome on standard karyotypes; the results are discussed in light of gene assignments, extensive chromosome band conservation among the Bovidae, and inconsistencies in domestic cattle chromosome nomenclatures.

Mapping of repetitive bovine DNA sequences on cattle Y chromosomes

Three male-specific PCR products of the sequences BC1.2, lambda ES6.0, and BRY.1 were used as probes for Southern blot analyses. Each of these probes generated a complex male-specific band pattern, which showed some quantitative variations among bulls. Hybridization patterns obtained with the BC1.2 and lambda ES6.0 PCR products were interrelated. Chromosomal locations of these repeats were determined by hybridizing the tritiated PCR products in situ to male metaphase spreads. The BC1.2 and lambda ES6.0 PCR products hybridized to Yp13-->p12, whereas the BRY.1 PCR product hybridized over the entire Y chromosome. In addition, the BC1.2 and lambda ES6.0 PCR products hybridized to the distal half of the acrocentric Y chromosome of Bos indicus, indicating that the short arm of the B. taurus Y chromosome is homologous with the telomeric end of the B. indicus Y and supporting the notion that the Y chromosomes of these two species differ by a pericentric inversion.

Physical mapping of the lysozyme gene family in cattle

Amplification of an ancestral lysozyme gene in artiodactyls is associated with the evolution of foregut fermetation in the ruminant lineage and has resulted in about ten lysozyme genes in true ruminants. Hybridization of a cow stomach lysozyme 2 cDNA clone to restricted DNAs of a panel of cowxhamster hybrid cell lines revealed that all but one of the multiple bovine-specific bands segregate concordantly with the marker for bovine syntenic group U3 [Chromosome (Chr) 5]. The anomalous band was subsequently mapped to bovine syntenic group U22 (Chr 7) with a second panel of hybrids representing all 31 bovine syntenic groups. By two-dimensional pulsed-field gel electrophoresis the lysozyme genes on cattle Chr 5 were shown to be clustered on a 2- to 3-Mb DNA fragment, while the lactalbumin gene and pseudogenes that are paralogous and syntenic with the lysozymes were outside the lysozyme gene cluster. Chromosomal fluorescence in situ hybridization of a cocktail of lysozyme genomic clones localized the lysozyme gene cluster to cattle Chr 5 band 23, corroborating the somatic cell assignment.