Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Education, Shanghai Ocean University, Shanghai, China.
PLoS One. 2011;6(7):e22886. doi: 10.1371/journal.pone.0022886. Epub 2011 Jul 27.
Iron is one of the most important minor elements in the shells of bivalves. This study was designed to investigate the involvement of ferritin, the principal protein for iron storage, in shell growth. A novel ferritin subunit (Fth1) cDNA from the freshwater pearl mussel (Hyriopsis cumingii) was isolated and characterized. The complete cDNA contained 822 bp, with an open reading frame (ORF) of 525 bp, a 153 bp 5' untranslated region (UTR) and a 144 bp 3' UTR. The complete genomic DNA was 4125 bp, containing four exons and three introns. The ORF encoded a protein of 174 amino acids without a signal sequence. The deduced ferritin contained a highly conserved motif for the ferroxidase center comprising seven residues of a typical vertebrate heavy-chain ferritin. It contained one conserved iron associated residue (Try27) and iron-binding region signature 1 residues. The mRNA contained a 27 bp iron-responsive element with a typical stem-loop structure in the 5'-UTR position. Copy number variants (CNVs) of Fth1 in two populations (PY and JH) were detected using quantitative real-time PCR. Associations between CNVs and growth were also analyzed. The results showed that the copy number of the ferritin gene of in the diploid genome ranged from two to 12 in PY, and from two to six in JH. The copy number variation in PY was higher than that in JH. In terms of shell length, mussels with four copies of the ferritin gene grew faster than those with three copies (P<0.05), suggesting that CNVs in the ferritin gene are associated with growth in shell length and might be a useful molecular marker in selective breeding of H. cumingii.
铁是双壳类贝壳中的一种重要微量元素。本研究旨在探讨铁蛋白（主要的铁储存蛋白）在贝壳生长中的作用。本研究从淡水珍珠贝（Hyriopsis cumingii）中分离并鉴定了一种新型铁蛋白亚基（Fth1）cDNA。该 cDNA 全长 822bp，包含一个 525bp 的开放阅读框（ORF）、一个 153bp 的 5'非翻译区（UTR）和一个 144bp 的 3'UTR。完整的基因组 DNA 长 4125bp，包含四个外显子和三个内含子。ORF 编码一个 174 个氨基酸的无信号肽蛋白。该铁蛋白包含一个高度保守的亚铁氧化酶中心基序，由典型的脊椎动物重链铁蛋白的七个残基组成。它包含一个保守的铁结合残基（Try27）和铁结合区域特征 1 残基。mRNA 的 5'-UTR 位置含有一个 27bp 的铁反应元件，具有典型的茎环结构。使用实时定量 PCR 检测了两个群体（PY 和 JH）中 Fth1 的拷贝数变异（CNVs）。还分析了 CNVs 与生长的关系。结果表明，PY 中二倍体基因组中铁蛋白基因的拷贝数范围为 2 到 12，而 JH 中的拷贝数范围为 2 到 6。PY 中的拷贝数变异高于 JH。在壳长方面，携带四个铁蛋白基因拷贝的贻贝生长速度快于携带三个拷贝的贻贝（P<0.05），表明铁蛋白基因中的 CNVs 与壳长生长有关，可能是珍珠贝选择性育种的有用分子标记。
