Search

Reports on the regulation region of larval serum protein gene, Bombyx mori, (BmLSP). Indication that the first intron, the first exon, the central promoter region and 5'-upstream region, is cloned from genomic DNA of the silkworm, SujuxMinghu; Use of PCR and restriction endonuclease methods; Construction of a series of luciferase reporter plasmids, driven by different length of BmLSP promoters; Investigation into the regulation elements and foreign insect hormones' effect on the BmLSP promoter activity, via the transient expression system in BmN cells; Finding that the BmLSP promoter activity is higher; Result when the first intron or the element in 5'-upstream region harboring the homologous sequence with the first intron of light-chain fibroin gene (EHIF) is deleted; Suggestion that the first intron and EHIF contain the main positive cis-acting elements; The negative effect of the inactive mariner transposable element (MTE); Effects of juvenile hormone analogue (JHA) on the BmLSP promoter activity demonstrating a dose-dependent manner; Idea that low concentration treatments increase the BmLSP promoter activity, while high concentration treatments decrease it; Assertion that insect ecdysone (MH) treatments present no significant effect.

To characterize the effects of cetyltriethylammonium bromide (CTAB) on the transcription of gp64 promoter from Bombyx mori nucleopolyhedrovirus (BmNPV), the plasmid pBmgp64Luc used in transient expression assay system was constructed by using the luciferase gene as a reporter under the control of BmNPV gp64 promoter. When the Bombyx mori cells (Bm-N) were transfected with the pBmgp64Luc, different treatments were undertaken. We found that the transient expression activity of luciferase could not be augmented directly by CTAB treatment alone, but could be enhanced more than 2 times by BmNPV treatment alone at a multiplicity of infection (MOI) of 0.5. Through co-treatment with 0.1 µg ml−1 of CTAB and BmNPV at a MOI of 0.5, the enzymatic activity increased 5.21 times. We presumed that the stimulation of transcription of BmNPV gp64 promoter by CTAB was mediated by viral factors from BmNPV. In addition, the time curves of luciferase activity in cells transfected with pBmgp64Luc and transactivated by virus were observed. [ABSTRACT FROM AUTHOR]

An experimental study was undertaken to quantify the effects of cetyltriethylammonium bromide (CTAB) on the replication of Bombyx mori nucleopolyhedrovirus (BmNPV) and the transcriptionalactivity of BmNPV ie-1 promoter. The results demonstrated that the budded virus (BV) titer rose about 3.7-fold by adding CTAB to the culture media up to 0.1 μ g ml-1 in infected Bm-N cells with a wild-type BmNPV. The transient expression level of luciferase driven by BmNPV ie-1 promoter was enhanced by more than 3-fold in the presence of 0.1 μ g ml-1 of CTAB in uninfected insect cells via a transient expression system. Contrary to the rise in BV titer, the polyhedra inside the nucleus of infected cells dropped linearly from 4.0 × 106 ml-1 down to 2.1 × 106 ml-1 with in a range of CTAB concentrations from 0 to 0.25 μ g ml-1. The same trend in expression level of β - galactosidase or phytase was given when the Bm-N cells or fifth-instar silkworm larvae infected with a recombinant BmNPV containing the β - galactosidase or phytase reporter gene driven by the polyhedrin promoter. We deduced that CTAB appeared to affect the virus bi-phasic life cycle stages and production pathways, resulting in an enhancement in BV production and a suppression of occluded virus (OV) production and expression of foreign genes controlled by the polyhedrin promoter. [ABSTRACT FROM AUTHOR]