Martinez Laisel, Almagro Juan C, Coll Jose L, Herrera Rene J
Department of Biological Sciences, Florida International University, University Park, OE 304, Miami, FL 33199, USA.
Insect Biochem Mol Biol. 2004 Apr;34(4):343-52. doi: 10.1016/j.ibmb.2003.12.002.
The single intron of the heavy-chain fibroin gene in domesticated (Bombyx mori) and wild (B. mandarina) silk moths has a length of approximately 1000 nucleotides. It is located only 57 bp from the gene's core promoter and harbors multiple AT-rich regulatory elements that have been found to enhance the basal level of transcription in vitro. In this work, the intronic nucleotide variability among members of both Bombyx species is analyzed. The intron sequences of B. mori strains k120 and Nistari, as well as B. mandarina specimens from Japan and Korea, were obtained. This information was compared with the previously reported sequences of B. mori strains p50 and C-108, as well as an additional B. mandarina specimen collected in Japan. We found a total of 26 variant positions, including variants shared by members of both species and species-specific changes. The potential functional role of these variants was investigated by using the program MatInspector to search for putative binding sites of transcription factors within the intron. We detected a multitude of putative binding elements distributed along the entire intronic sequence. Among them, 22 correspond to protein binding domains that are known to regulate fibroin transcription. The mapping of multiple variant positions within these putative binding sequences as well as in known regulatory elements of the intron argue for functional significance on the regulation of transcription.
家蚕（Bombyx mori）和野桑蚕（B. mandarina）重链丝心蛋白基因的单个内含子长度约为1000个核苷酸。它距离基因的核心启动子仅57 bp，含有多个富含AT的调控元件，这些元件已被发现在体外可增强基础转录水平。在这项研究中，分析了两种家蚕物种成员之间内含子核苷酸的变异性。获得了家蚕品系k120和Nistari以及来自日本和韩国的野桑蚕标本的内含子序列。将这些信息与先前报道的家蚕品系p50和C - 108的序列以及在日本收集的另一个野桑蚕标本进行了比较。我们总共发现了26个变异位点，包括两个物种成员共有的变异以及物种特异性变化。通过使用MatInspector程序搜索内含子中转录因子的假定结合位点，研究了这些变异的潜在功能作用。我们在整个内含子序列中检测到大量假定的结合元件。其中，22个对应于已知调节丝心蛋白转录的蛋白质结合结构域。这些假定结合序列以及内含子已知调控元件内多个变异位点的定位表明其对转录调控具有功能意义。
