Transposable Elements in Fish Chromosomes: A Study in the Marine Cobia Species
Transposable Elements in Fish Chromosomes: A Study in the Marine Cobia Species
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DOI：
10.1159/000354309
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发表时间：
2013-01-01
影响因子：
1.7
通讯作者：
Molina, W. F.
中科院分区：
文献类型：
--
作者：
Costa, G. W. W. F.;Cioffi, M. B.;Molina, W. F.
加拿大Rachycentron canadum是Rachycentridae科的独特代表，由于其在海洋鱼类养殖中的潜在用途，一直是生物技术研究的重要课题。该物种在其染色体上的基因和多基因家族定位方面进行了广泛的研究。虽然一些生物体的大部分基因组是由重复的DNA序列组成的，但这些元素的起源和分散在很大程度上仍然是未知的。结果表明，该研究具有重要的生物学意义和应用价值。因此，本文采用荧光原位杂交技术对该物种染色体上的转座因子（TE） Tol2、非ltr反转录转座子Rex1和Rex3以及18S和5S rRNA基因进行了定位。Tol2 TE属于hAT转座子家族，均匀分布在染色体的正染色质区域，但与18S rDNA位点存在大量共定位。Rex1和Rex3的杂化信号呈半任意分布模式，在正色区和异色区呈差异色散。Rex1元件优先关联于异染色质区域，而Rex3则很少分布于染色体的正染色质区域。te与18S和5S rDNA共定位显示了重复序列的复杂染色体区域。此外，Rex1和Rex3在所有异染色质区域的非优先分布，以及与18S rDNA序列相关的Tol2转座子的优先分布，揭示了该物种基因组中te的独特组织模式。te的异质染色体定殖可能使该物种的异色区具有不同的进化速率。(C) 2013 S. Karger AG，巴塞尔
Rachycentron canadum, a unique representative of the Rachycentridae family, has been the subject of considerable biotechnological interest due to its potential use in marine fish farming. This species has undergone extensive research concerning the location of genes and multigene families on its chromosomes. Although most of the genome of some organisms is composed of repeated DNA sequences, aspects of the origin and dispersion of these elements are still largely unknown. The physical mapping of repetitive sequences on the chromosomes of R. canadum proved to be relevant for evolutionary and applied purposes. Therefore, here, we present the mapping by fluorescence in situ hybridization of the transposable element (TE) Tol2, the non-LTR retrotransposons Rex1 and Rex3, together with the 18S and 5S rRNA genes in the chromosome of this species. The Tol2 TE, belonging to the family of hAT transposons, is homogeneously distributed in the euchromatic regions of the chromosomes but with huge colocalization with the 18S rDNA sites. The hybridization signals for Rex1 and Rex3 revealed a semi-arbitrary distribution pattern, presenting differentiated dispersion in euchromatic and heterochromatic regions. Rex1 elements are associated preferentially in heterochromatic regions, while Rex3 shows a scarce distribution in the euchromatic regions of the chromosomes. The colocalization of TEs with 18S and 5S rDNA revealed complex chromosomal regions of repetitive sequences. In addition, the nonpreferential distribution of Rex1 and Rex3 in all heterochromatic regions, as well as the preferential distribution of the Tol2 transposon associated with 18S rDNA sequences, reveals a distinct pattern of organization of TEs in the genome of this species. A heterogeneous chromosomal colonization of TEs may confer different evolutionary rates to the heterochromatic regions of this species. (C) 2013 S. Karger AG, Basel