| Insect neuropeptides play key roles in regulation of metabolism, development, reproduction, rhythm, diapause, behavior and learning, and it is important to demonstrate the gene transcriptional regulation of insect neuropeptides. Prothoracicotropic hormone (PTTH) plays a central role in controlling growth, molting, and metamorphosis in insects by stimulating the prothoracic glands to synthesize and release the molting hormone, ecdysone. In present paper, the transcriptional regulation, development profile of PTTH gene were analysised, and the development expression of Torso gene, the receptor of PTTH gene, and other 18 neuropeptides genes in Bombyx mori.The promoter of PTTH gene of Bombyx mori (Bom-PTTH) was cloned and sequenced with the length of 1140bp. The transcriptional regulatory elements in the promoter of Bom-PTTH gene were predicted using Matinspector software, including MEF2, TATA box, pbx-1, et al. The recombinant plasmids were constructed, which including different fragments of PTTH promoter, and then were used for transient transfection assays. The results demonstrated that the fragment spanning-110 to+33 bp of the Bom-PTTH promoter showed high ability to support reporter gene expression; the region of+34 to+192 bp and-512 to-111 bp repressed the promoter activity in the insect cell lines BmN and Bm 5. The MH can enhance the transcriptional activity of Bom-PTTH promoter, but the JH inhibit the activity. The activity of enhance and inhibit were depended on the concentration of the MH and JH.The myocyte enhancer factor-2 (MEF2) was identified as.a key transcriptional factor for regulation of the expression of PTTH gene in B. mori. A new isoform of the MEF2 was cloned and sequenced from B. mori, which named as MEF2B. The open reading frame (ORF) of the new isoform is 1218 bp length, encoding 405 amine acids. The MEF2B shows 12 nucleotides absence of (GCACTCACAAAG) and three nucleotides mutation to the former BMEF2A. The MEF2B contains different domains, the 57 aa MADS-Box, the 29 aa MEF2 binding domain and the 319 aa transcriptional activity domain. Using the SWISS-MODEL Prediction Server, the 3-D structure of BMEF2B was modeled as the pattern ofα-β-β-α-α. The BMEF2B mRNA in the 5th larval instar changed with the developmental stage, which is lowest in the 1st day, increased to highest amount at 6th day, and then decreased.Recently, the torso gene was defined as the receoptor of PTTH gene in B. mori. The mRNA of PTTH and torso were detected in the complex of brain and suboesophageal ganglion (Br-SG). Using real-time PCR, the developmental expression of PTTH gene and torso in Br-SGs were measured from the 1st day of 5th larval instar to adult in B. mori. The PTTH mRNA in Br-SGs in the 5th larval instar is higher than that in wandering pupal stage, pupal stage and adult, and the highest peak lies on the 6th day in 5th instar. The PTTH mRNA kept high stable level from day 4 to 8 of pupal stage, then, decreased abruptly. After eclosion, the PTTH mRNA decreased to a low level. The level of torao gene mRNA in 5th laval instar and wandering pupae were almost same, and higher than other 2 stages. There are two peaks of torso mRNA in the day 2 and 6 in 5th instar, respectively. Before day 3 of wandering pupal, the torso mRNA increased dramatically then decreased before pupae. During pupal stage, the torso mRNA in Br-SGs kept low level consistently.The developmental expression profiles of the mRNA in Br-SGs of 18 neuropeptide genes were demonstrated, which varied with the different specific genes. Among the 18 genes we investagted, the mRNA of 15 genes showed high level during the early stage (day 1-3) of 5th larval instar, which including DH-PBAN, EH, NPL, FMRFamide neuropeptids. The CCAP gene expressed high level in early pupal stage. The SIFamide gene kept high level of mRNA after eclosion, but the other 17 genes showed low level.
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