45S rDNA regions are chromosome fragile sites expressed as gaps in vitro on metaphase chromosomes of root-tip meristematic cells in Lolium spp.
45S rDNA regions are chromosome fragile sites expressed as gaps in vitro on metaphase chromosomes of root-tip meristematic cells in Lolium spp.
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45S rDNA 区域是染色体脆弱位点，在体外表现为黑麦草根尖分生细胞中期染色体上的缺口
DOI：
10.1371/journal.pone.0002167
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发表时间：
2008-05-14
期刊：
影响因子：
3.7
通讯作者：
Li L
中科院分区：
文献类型：
--
作者：
Huang J;Ma L;Yang F;Fei SZ;Li L
背景在人类中，染色体脆性位点是特别容易在中期染色体上的一个或两个染色单体中自发地或在DNA合成部分抑制后形成非染色间隙、收缩或断裂的区域，并且已经被很好地鉴定。到目前为止，还没有报道过类似于人类染色体的植物染色体脆性位点。方法与结果在对多花黑麦草染色体rDNA进行细胞学定位的过程中，发现多花黑麦草大多数细胞的染色体加染色体片段数往往超过预期的14条。CV.球员通过使用常规染色体制备程序进行细胞学检查。进一步用45SrDNA作探针进行荧光原位杂交（FISH），结果表明，根尖细胞中染色体数目大于14+染色体片段数是由于染色体断裂或间隙形成所致（称为染色体病变）在45S rDNA位点，86%的细胞出现染色体断裂或间隙，且均发生在45SrDNA位点。CV. Player，以及在L.多花CV.第一名染色质耗尽或deconcensation发生在45S rDNA区域内的各个位置，这表明45S rDNA位点的病变相对于它们在rDNA区域内的位置的异质性。结论本研究中观察到的染色体损伤与人类染色体脆性位点的细胞学特征非常相似，因此我们认为，在离体培养中，黑麦草属植物染色体的高频率损伤是45SrDNA脆性位点表达的结果。脆性位点自发表达的可能原因及其潜在的生物学意义进行了讨论。
Background In humans, chromosome fragile sites are regions that are especially prone to forming non-staining gaps, constrictions or breaks in one or both of the chromatids on metaphase chromosomes either spontaneously or following partial inhibition of DNA synthesis and have been well identified. So far, no plant chromosome fragile sites similar to those in human chromosomes have been reported. Methods and Results During the course of cytological mapping of rDNA on ryegrass chromosomes, we found that the number of chromosomes plus chromosome fragments was often more than the expected 14 in most cells for Lolium perenne L. cv. Player by close cytological examination using a routine chromosome preparation procedure. Further fluorescent in situ hybridization (FISH) using 45S rDNA as a probe indicated that the root-tip cells having more than a 14-chromosome plus chromosome fragment count were a result of chromosome breakage or gap formation in vitro (referred to as chromosome lesions) at 45S rDNA sites, and 86% of the cells exhibited chromosome breaks or gaps and all occurred at the sites of 45S rDNA in Lolium perenne L. cv. Player, as well as in L. multiflorum Lam. cv. Top One. Chromatin depletion or decondensation occurred at various locations within the 45S rDNA regions, suggesting heterogeneity of lesions of 45S rDNA sites with respect to their position within the rDNA region. Conclusions The chromosome lesions observed in this study are very similar cytologically to that of fragile sites observed in human chromosomes, and thus we conclude that the high frequency of chromosome lesions in vitro in Lolium species is the result of the expression of 45S rDNA fragile sites. Possible causes for the spontaneous expression of fragile sites and their potential biological significance are discussed.
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影响因子：
64.5
作者：
Casper, AM;Nghiem, P;Glover, TW
通讯作者：
Glover, TW
DOI：
10.1073/pnas.95.14.8141
发表时间：
1998-07-07
影响因子：
11.1
作者：
Mishmar, D;Rahat, A;Kerem, B
通讯作者：
Kerem, B
影响因子：
16
作者：
Lawrence, RJ;Earley, K;Pikaard, CS
通讯作者：
Pikaard, CS
影响因子：
3.7
作者：
BOLDOG, FL;WAGGONER, B;DRABKIN, HA
通讯作者：
DRABKIN, HA
DOI：
10.1196/annals.1322.002
发表时间：
2004-01-01
期刊：
SIGNAL TRANSDUCTION AND COMMUNICATION IN CANCER CELLS
影响因子：
--
作者：
B端ttel, I;Fechter, A;Schwab, M
通讯作者：
Schwab, M