Ali Ahmad, Abdullah Muhammad, Babar Masroor Ellahi, Javed Khalid, Nadeem Asif
Department of Livestock Production, University of Veterinary and Animal Sciences, Outfall Road, Lahore 54000, Pakistan.
J Genet. 2008 Dec;87(3):219-27. doi: 10.1007/s12041-008-0035-1.
An investigation to understand the dynamics and biological significance of fragile site expression, and identification of 5-fluorodeoxyuridine (FUdR) induced chromosomal gaps/breaks, were carried out in an experimental flock of 45 Suffolk sheep. The statistical comparison revealed, highly significant variation in the frequency of chromosomal fragile site expression between control and FUdR cultures. Mean (+/- S.D.) values for cells with gaps and breaks, or aberrant cell count (AC), and the number of aberrations (NoA) per animal were 2.02 +/- 0.34, 2.42 +/- 0.48, 13.26 +/- 0.85 and 21.87 +/- 1.88 (P lessthan 0.01) in control and FUdR cultures, respectively. The comparison of age revealed nonsignificant variation between control and FUdR cultures. The G-band analysis of fragile site data revealed gaps in 29 autosomal and two X-chromosomal bands in the control cultures, whereas FUdR treated cultures scored 78 unstable bands in autosomes of which 56 were significantly fragile. X-chromosomes expressed breaks and gaps in six G-negative bands and five of them (Xq13, Xq15, Xq17, Xq24 and Xq26) were significantly fragile. The distribution comparison of autosomal fragile sites between sex groups did not reveal any significant variation. Female X-chromosomes were significantly more fragile than the male X-chromosomes. The distribution comparison for age groups (lambs versus adults) revealed significantly higher number of fragile bands in adults. Comparison of published data on reciprocal translocations in sheep with the fragile-site data obtained in this study indicated that the break sites of both phenomena were correlated. Similarities were also found between fragile sites and breakpoints of evolutionary significance in family Bovidae.
在一个由45只萨福克绵羊组成的实验羊群中，开展了一项旨在了解脆性位点表达的动态变化及其生物学意义，以及鉴定5-氟脱氧尿苷（FUdR）诱导的染色体间隙/断裂的研究。统计比较显示，对照培养物和FUdR培养物之间染色体脆性位点表达频率存在极显著差异。对照培养物和FUdR培养物中，有间隙和断裂的细胞的平均（±标准差）值、异常细胞计数（AC）以及每只动物的畸变数量（NoA）分别为2.02±0.34、2.42±0.48、13.26±0.85和21.87±1.88（P＜0.01）。年龄比较显示，对照培养物和FUdR培养物之间无显著差异。对脆性位点数据的G带分析显示，对照培养物中有29个常染色体带和2个X染色体带出现间隙，而经FUdR处理的培养物在常染色体上有78个不稳定带，其中56个为显著脆性带。X染色体在6个G阴性带中出现断裂和间隙，其中5个（Xq13、Xq15、Xq17、Xq24和Xq26）为显著脆性带。性别组之间常染色体脆性位点的分布比较未显示出任何显著差异。雌性X染色体比雄性X染色体显著更脆弱。年龄组（羔羊与成年羊）的分布比较显示，成年羊中脆性带的数量显著更多。将已发表的绵羊相互易位数据与本研究中获得的脆性位点数据进行比较表明，这两种现象的断裂位点具有相关性。在牛科动物中，脆性位点与具有进化意义的断点之间也发现了相似之处。
