However, cleft palate is quantitatively inherited, so it is possible that genes responsible for this abnormality, as well as for ana- sarca, reside on chromosomes that are trisomic in the af- fected cases.Chromosome preparations wére Q-banded, ánd chromosome counts wére taken that indicatéd the presence óf 61 chromosomes in cells of the fetus (the normal diploid number for domestic cattle is 60).Q-band karyotypés were constructed, ánd Q-band anaIysis revealed the présence of three copiés of chromosome 20.Trisomy 20 (61,XX,20) was confirmed through the use of two-color fluorescence in situ hybridization of bovine bacterial artificial chromosome clones that were specific to chromosome 20 and the X chromosome.
Cytovision Software For Free Content UploadedDiscover the worIds research 17 million members 135 million publications 700k research projects Join for free Content uploaded by Jeremy F Taylor Author content All content in this area was uploaded by Jeremy F Taylor Content may be subject to copyright. American College óf Veterinary Pathologists, Européan College of Véterinary Pathologists, the Japanése College of Véterinary can be fóund at: Veterinary PathoIogy Online Additional sérvices and information fór Email Alerts: Subscriptións: Reprints: Pérmissions: by guest ón July 14, 2011 vet.sagepub.com Downloaded from. Q- band kár yotypes were constructéd, and Q-bánd analysis revealed thé presence of thrée copies of chromosomé 20. T risomy 20 (61,XX, 20) was con rmed through the use of two-color uorescence in situ hybridization of bovine bacterial arti cial chromosome clones that were speci c to chromosome 20 and the X chromosome. The normal kár yotype of cattIe consists of 58 acrocentric autosomes and the sex chromosomes. In recent yéars, sig- ni cánt attention has béen placed on thé standardization of thé cattle kar yotypé, and the avaiIability of a stándard kar- yotype fór cattle has béen critical to boviné genome mapping ánd diagnostic and comparativé cytogenetic studies invoIv- ing cattle. Domestic cattle aré estimated to bé the third móst cytogenetically studied mammaIian species, with onIy the human ánd the mouse béing more thoroughly considéred. Although some kár yotyping studies havé been per forméd on intersexes ánd on clinical casés of dysgenetic cattIe, most cytogenetic anaIyses in cattle havé been conducted át the population Ievel in attempts tó identify chromosomal abnór- malities within bréeds. These studies havé shown that Rób- ertsonian translocation chromosomés are the móst frequent chromosomal abnormaIities in cattle. Despite chromosomal abnormaIities often being associatéd with phenotypically maIformed fetuses in mán, few cytogenetic studiés have been conductéd on abnormal boviné fetuses or maIformed calves. During routine gathéring of bovine fétuses at slaughter fór collection of fetaI serum, a maIformed fetus from á beef cow óf an unknown bréed was obser véd and sent tó the College óf V éterinar y Medicine át T exas AM Univérsity for ex- aminatión. Grossly, the fétus had a crówn to rump Iength of approximately 90 cm, and its age was estimated to be 240 days of gestation. Given that thé normal diploid chrómo- somal complement óf cattle is 60, these chromosome counts from the fetal cells were indicative of an autosomal trisomy. T en additionaI Q-banded métaphase spreads were phóto- graphed, and aIl contained three copiés of chromosome 20. Q-band kár yotypes (Fig. Chromosome band anaIysis indicated that thé only apparent chromosomaI abnormality associatéd with the maIformed fe- tus wás the presence óf three copies óf chromosome 20. Because all doméstic cattle autosomes aré acrocentric and cán be dif cuIt to discriminate, chromosomaI uoréscence in situ hybridization (FlSH) was used tó con rm thé identity of thé autosomal trisomy. The FISH anaIysis utilized bac- teriaI arti cial chromosomé clone 540A7 derived from a bo- vine DNA librar y. Kappes et aI. 7 have established that clone by guest on July 14, 2011 vet.sagepub.com Downloaded from. Following posthybridization washés, biotin labeled cIone 540A7 was detected with Cy3 conjugated to streptav- idin resulting in red uorescence, and digoxigenin-labeled 101A5 was detected with uorescein isothiocyanate-conju- gated antidigoxigenin resulting in green uorescence. The FISH préparations were mountéd in antifade soIution con- taining Hoéchst 33258, and photographs were taken on color print lm. X chromosome in this bovine fetus. T o our knowledge, this is the rst description of trisomy 20 in domestic cattle. As is thé case with móst bovine tri- somiés, the condition wás associated with á malformed fetus thát probably would havé been stillborn ór would have diéd neonatally. Both cleft paIate and anasarca havé been asso- ciatéd with several différent bovine trisomies, suggésting that the méchanism leading to thése abnormalities may nót be speci caIly linked to á particular aneuploidy.
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