Expression and localization of Bombyx mori nucleopolyhedrovirus GP37.

Mitochondria play an essential role in intracellular energy metabolism. This study described the involvement of Bombyx mori nucleopolyhedrovirus (BmNPV) GP37 (BmGP37) in host mitochondria. Herein, the proteins associated with host mitochondria isolated from BmNPV-infected or mock-infected cells by two-dimensional gel electrophoresis were compared.

Potential for small RNA production against Bombyx mori latent virus in Bombyx mori ovaries.

Bombyx mori latent virus (BmLV) is a positive, single-stranded insect RNA virus closely related to plant maculaviruses. BmLV was first isolated from Bombyx mori ovary-derived cell line BmN-4, and this virus has already infected most B. mori-derived cultured cell lines.

Whole-genome sequencing and comparative transcriptome analysis of Bombyx mori nucleopolyhedrovirus La strain.

The Bombyx mori nucleopolyhedrovirus (BmNPV) La is a variant BmNPV strain isolated in Laos. La has different features from BmNPV type strain T3 in virulence, production of the polyhedrin protein, and the formation of multicapsid occlusion-derived viruses. Here, the whole-genome sequence of La was compared to the sequences of nine BmNPV and two Bombyx mandarina nucleopolyhedrovirus strains.

Infectious Virions of Are Incorporated into Occlusion Bodies.

The (BmLV) belongs to the unassigned plant virus family and contains a positive-sense, single-stranded RNA genome. BmLV has infected almost all -derived cultured cell lines through unknown routes. The source of BmLV infection and the BmLV life cycle are still unknown.

[Persistent virus in the silkworm cell lines: Bombyx mori latent virus].

Bombyx mori latent virus (BmLV) is a positive, single-stranded insect RNA virus with a close relationship to plant tymoviruses and currently classified as an "unclassified" tymovirus. BmLV is accumulated at extremely high levels only in cell lines derived from the silkworm, Bombyx mori, but it does not lead to lethality and establishes persistent infections. It was unknown whether BmLV affects the Baculovirus Expression Vector System using Bombyx mori nucleopolyhedrovirus, and how BmLV replicates and establishes persistent infections in insect cell lines.

Conversion of carlactone to carlactonoic acid is a conserved function of MAX1 homologs in strigolactone biosynthesis.

Strigolactones (SLs) are a class of plant hormones which regulate shoot branching and function as host recognition signals for symbionts and parasites in the rhizosphere. However, steps in SL biosynthesis after carlactone (CL) formation remain elusive. This study elucidated the common and diverse functions of MAX1 homologs which catalyze CL oxidation.

Transcriptome profiling reveals infection strategy of an insect maculavirus.

Bombyx mori macula-like virus (BmMLV) is a positive, single-stranded insect RNA virus that is closely related to plant maculaviruses. BmMLV is currently characterized as an unclassified maculavirus. BmMLV accumulates at extremely high levels in cell lines derived from the silkworm, Bombyx mori, but it does not lead to lethality and establishes persistent infections.

Expression profiles of cuticular protein genes in wing tissues during pupal to adult stages and the deduced adult cuticular structure of Bombyx mori.

We aimed to clarify the regulation of cuticular protein (CP) gene expression and the resulting insect cuticular layers by comparing the expression pattern of CP genes and related ecdysone-responsive transcription factor (ERTF) genes, the coding amino acid sequences of CP genes, and histological observation. The expression of CP and ERTF genes during pupal and adult stages was examined via qPCR. The number of CP genes expressed during pupal and adult stages decreased as compared to that during prepupal to pupation stages, particularly in CPRs.

Expression of matrix metalloproteinase genes during basement membrane degradation in the metamorphosis of Bombyx mori.

The present study was conducted to clarify the involvement of the basement membrane (BM) in insect metamorphosis through analysis of the expression profile of two types of metalloproteinase (MMP and ADAMTS) genes in several organs, their ecdysone involvement, and the histological change of BM. BM was observed around wing sac and in the wing cavity and around fat bodies at the W0 stage but disappeared after the W3 stage, and wing discs evaginated and fat body cells scattered after the W3 stage. The disappearance of the BM of midgut and silk glands was not observed after the W3 stage, but degenerated epithelium cells in the midgut and shrunken cells in the silk gland were observed after the W3 stage.

The angiotensin-converting enzyme (ACE) gene family of Bombyx mori.

We previously reported regarding an ecdysone-inducible angiotensin-converting enzyme (ACE) gene. We found another four ACE genes in the Bombyx genome. The present study was undertaken to clarify the evolutionally changed function of the ACE of Bombyx mori.

Investigation of kinetic-order sensitivities in metabolic reaction networks.

Kinetic-order sensitivity (the ratio of relative change in a dependent variable to the relative change in a kinetic order in a power-law-type differential equation) has recently become an important indicator in metabolic pathway analysis using mathematical models with parameter values determined from time-series data on cellular metabolite concentrations. Here, we discuss a potential problem in calculating kinetic-order sensitivities. When the steady-state metabolite concentration is less than unity, a slight increase in the kinetic order changes the metabolite concentration in the incorrect direction, yielding a kinetic-order sensitivity value with an incorrect sign.

Cloning and characterization of carboxyl terminus of heat shock cognate 70-interacting protein gene from the silkworm, Bombyx mori.

Carboxyl terminus of heat shock cognate 70-interacting protein (CHIP) is an evolutionarily conserved E3 ubiquitin ligase across different eukaryotic species and is known to play a key role in protein quality control. CHIP has two distinct functional domains, an N-terminal tetratricopeptide repeat (TPR) and a C-terminal U-box domain, which are required for the ubiquitination of numerous labile client proteins that are chaperoned by heat shock proteins (HSPs) and heat shock cognate proteins (HSCs). During our screen for CHIP-like proteins in the Bombyx mori databases, we found a novel silkworm gene, Bombyx mori CHIP.

Ecdysteroid promotes cell cycle progression in the Bombyx wing disc through activation of c-Myc.

Developmental switching from growth to metamorphosis in imaginal primordia is an essential process of adult body planning in holometabolous insects. Although it is disciplined by a sequential action of the ecdysteroid, molecular mechanisms linking to cell proliferation are poorly understood. In the present study, we investigated the expression control of cell cycle-related genes by the ecdysteroid using the wing disc of the final-instar larvae of the silkworm, Bombyx mori.

Infection studies of nontarget mammalian cell lines with Bombyx mori macula-like virus.

Bombyx mori-derived cell lines are generally used for Bombyx mori nucleopolyhedrovirus (BmNPV)-based baculovirus expression vector system (BEVS). However, almost all of the B. mori-derived cell lines are persistently infected with Bombyx mori macula-like virus (BmMLV).

Inactivation of Bombyx mori macula-like virus under physical conditions.

The Bombyx mori macula-like virus (BmMLV) is a member of the genus Maculavirus, family Tymoviridae, and contains a positive-sense single-stranded RNA genome. Previously, we reported that almost all B. mori-derived cell lines have already been contaminated with BmMLV via an unknown infection route.

Expression of recombinant proteins by BEVS in a macula-like virus-free silkworm cell line.

We previously established the first Bombyx mori macula-like virus (BmMLV)-free cell line (BmVF cells) from a B. mori embryo. In this study, we evaluated the expression of recombinant proteins in BmVF cells using a B.

Long-term adaptation of the Bombyx mori BmN4 cell line to grow in serum-free culture.

Bombyx mori ovary-derived BmN4 cells have been successfully adapted to a commercial serum-free medium (SFM; SF900-II) by gradually reducing the serum-containing TC-100 medium content from 100 to 0% (v/v). The BmN4 cells adapted to the SFM (BmN-SFM) adhered strongly to the culture flask and showed altered cell morphology. The BmN-SFM was subcultured 200 times, and the population doubling time was 4.

Stage-specific activation of the E74B promoter by low ecdysone concentrations in the wing disc of Bombyx mori.

To understand the transcriptional regulation of E74B by low concentrations of ecdysone, the promoter activity of Bombyx mori E74B was assessed in the B. mori wing disc using a transient reporter assay. We identified the transcription start sites of BmE74B and found that the core promoter region consists of initiator (Inr) and downstream promoter elements (DPE).

Involvement of HSC70-4 and other inducible HSPs in Bombyx mori nucleopolyhedrovirus infection.

Heat shock proteins (HSPs) and heat shock cognate proteins (HSCs) function as molecular chaperones under normal cellular conditions. In this report, we describe the role of Bombyx mori heat shock cognate protein 70-4 (BmHSC70-4), which is a constitutively expressed member of the heat shock protein 70 (HSP70) family, in B. mori nucleopolyhedrovirus (BmNPV) infection.

Ecdysone-responsive transcriptional regulation determines the temporal expression of cuticular protein genes in wing discs of Bombyx mori.

The present study was conducted to clarify the regulatory mechanism of cuticular protein genes of Bombyx mori expressed in wing discs in the prepupal stage. BHR3, BHR4, E74A, and ßFTZ-F1 were successively expressed in wing discs at the pre-pupal stage. BHR3 showed different ecdysone responsiveness from other ecdysone-responsive transcription factors (ERTFs) and was induced by ecdysone addition but showed decrease by ecdysone removal after treatment (ecdysone pulse).

Ecdysone-responsive transcription factors determine the expression region of target cuticular protein genes in the epidermis of Bombyx mori.

In the present study, we found that different ecdysone-responsive transcription factors were expressed differentially in different regions of the epidermis at around pupation. βFTZ-F1 transcripts were strongly but E74A transcripts were barely observed in the thoracic region of the epidermis, and vice versa in the abdominal region. Transcripts of all the examined transcription factors were observed in wing disc.

Expression of cuticular protein genes, BmorCPG11 and BMWCP5 is differently regulated at the pre-pupal stage in wing discs of Bombyx mori.

Through BLAST search of the genomic database of Bombyx mori, we found a clone, BmorCPG11, which has only putative BR-C binding sites in the 2 kb upstream region. Both BmorCPG11 and BR-Z2 were expressed in the cephalic region of the epidermis, differently from BR-Z1 and BR-Z4. BR-Z2 transcripts increased by the addition of 20-hydroxyl-ecdysone (20E), which was slightly inhibited by cycloheximide.

20-hydroxyecdysone and juvenile hormone analog prevent precocious metamorphosis in recessive trimolter mutants of Bombyx mori.

The trimolter mutants of Bombyx mori have four instead of five larval instars of normal tetramolters. Here, we show that the tetramolter was induced in the recessive trimolter European No.7 mutant (rt-E7) by application of either the juvenile hormone analog (JHA) or 20-hydroxyecdysone (20E).

Infection study of Bombyx mori macula-like virus (BmMLV) using a BmMLV-negative cell line and an infectious cDNA clone.

Previously, a novel macula-like virus was identified from Bombyx mori cultured cell line BmN and termed B. mori macula-like virus (BmMLV). BmMLV encodes a 6.

Ecdysone directly and indirectly regulates a cuticle protein gene, BMWCP10, in the wing disc of Bombyx mori.

The hormonal regulation of cuticle protein genes is a good model to study the molecular mechanism of signaling by ecdysteroids, which initiates each of the major developmental transitions in insects. This study was conducted to clarify the regulation of the expression of an ecdysone-inducible cuticle protein gene, BMWCP10. Induction of the BMWCP10 transcript by ecdysone was partly inhibited in the presence of cycloheximide, which implies that the BMWCP10 promoter is directly and indirectly activated by ecdysone.