The Baculovirus Uses a Captured Host Phosphatase to Induce Enhanced Locomotory Activity in Host Caterpillars

The baculovirus is a classic example of a parasite that alters the behavior or physiology of its host so that progeny transmission is maximized. Baculoviruses do this by inducing enhanced locomotory activity (ELA) that causes the host caterpillars to climb to the upper foliage of plants. We previously reported that this behavior is not induced in silkworms that are infected with a mutant baculovirus lacking its protein tyrosine phosphatase (ptp) gene, a gene likely captured from an ancestral host. Here we show that the product of the ptp gene, PTP, associates with baculovirus ORF1629 as a virion structural protein, but surprisingly phosphatase activity associated with PTP was not required for the induction of ELA. Interestingly, the ptp knockout baculovirus showed significantly reduced infectivity of larval brain tissues. Collectively, we show that the modern baculovirus uses the host-derived phosphatase to establish adequate infection for ELA as a virion-associated structural protein rather than as an enzyme

Impact Tensile Properties of Notched Titanium Alloy Bolt for Fairing Separation of Launch Vehicle

The payload fairing in Japan is fixed by a lot of notched bolts. These notched bolts were fractured by axial impact tensile using the explosive devices to separate the fairing. In this case, the stress waves and the oscillations propagate, which may seriously damage the satellites. In this study, the impact deformation and the fracture behavior of notched titanium alloy bolt was investigated using a split Hopkinson pressure bar method. The notched bolt specimen was made of commercial Ti-6Al-4V alloy. The maximum load value was increased with increasing the displacement rate. It can be said that the strain rate dependence of strength for Ti-6Al-4V alloy appeared. From the observation of fracture surface using a scanning electron microscope, compared with the quasi-static test, it was clear that the irregularities of the fractured surface at the impact tensile test became rough. Therefore, it was found that the brittle fracture was mainly observed due to the increase in displacement rate, which may mean that the mode of fracture changes from the transgranular to the intergranular. It was surmised that this change of fracture mode was caused by the high strain rate due to stress concentration of the notched part

Impact Tensile Properties of Notched Titanium Alloy Bolt for Fairing Separation of Launch Vehicle

The payload fairing in Japan is fixed by a lot of notched bolts. These notched bolts were fractured by axial impact tensile using the explosive devices to separate the fairing. In this case, the stress waves and the oscillations propagate, which may seriously damage the satellites. In this study, the impact deformation and the fracture behavior of notched titanium alloy bolt was investigated using a split Hopkinson pressure bar method. The notched bolt specimen was made of commercial Ti-6Al-4V alloy. The maximum load value was increased with increasing the displacement rate. It can be said that the strain rate dependence of strength for Ti-6Al-4V alloy appeared. From the observation of fracture surface using a scanning electron microscope, compared with the quasi-static test, it was clear that the irregularities of the fractured surface at the impact tensile test became rough. Therefore, it was found that the brittle fracture was mainly observed due to the increase in displacement rate, which may mean that the mode of fracture changes from the transgranular to the intergranular. It was surmised that this change of fracture mode was caused by the high strain rate due to stress concentration of the notched part

Reduced expression of viral genes in tissues of larvae infected with a <i>ptp</i>-disrupted virus.

<p>(A) Heatmaps of viral gene expression in 16 tissues of 5^th instar <i>B. mori</i> infected with BmNPV (WT) or BmPTPD (PTPD). The tissues were dissected from virus-infected larvae at 1, 2, 3, and 4 d p.i., and the expression of the early/late and very late genes <i>gp64</i> and <i>polh</i>, respectively, were quantified by qRT-PCR. Tissues from 5 to 30 larvae were mixed and used for the preparation of cDNAs. Abbreviations: FB, fat body; TR, trachea; BR, brain; CN, central nerve; PG, prothoracic gland; CA, corpora allata; HE, hemocyte; ASG, anterior silk gland; MSG, middle silk gland; PSG, posterior silk gland; MI, midgut; MT, Malpighian tubule; MU, muscle; IN, integument; OV, ovary; and TE, testis. (B) Expression of <i>polh</i> in fat body, trachea, central nerve, and brain. Tissues were dissected from four individual larvae at 4 d p.i. First strand cDNAs were generated from individual larvae and qRT-PCR was performed using primers that targeted the <i>polh</i> gene. Data shown are means ± SD (N = 4). *<i>p</i><0.05, Student's t-test.</p

BmPTPD produces fewer progeny in 5^th instar <i>B. mori</i> and shows a delay in late gene expression in BmN cells.

<p>Production of OBs (A) and BVs (B) in the hemolymph of larvae infected with BmNPV, BmPTPD, BmPTPDR or BmPTP-C119S at 4 d p.i. Data shown are means ± standard deviation (SD) (N = 4). *<i>p</i><0.05, one-way ANOVA with Tukey's post test in comparison to BmPTPD. (C) Western blot analysis of the expression of viral gene products in BmN cells infected with BmNPV, BmPTPD or BmPTPDR. The proteins were separated by SDS-PAGE, transferred to a nitrocellulose membrane, and immunoblotted with antibodies that recognize BmNPV early-expressed (DBP, BRO, and LEF3) or late-expressed (V-CHIA) proteins or actin. Similar results were obtained in two independent experiments. Abbreviations: WT, BmNPV; PTPD, BmPTPD; DR, BmPTPDR; and CS, BmPTPD-C119S.</p

PTP is an envelope-associated protein required for the production of normal virions.

<p>(A) Localization of PTP in the envelope and capsid fractions of budded virus. Western blot analysis of envelope (E) and capsid (C) fractions of budded virus (BV) of BmNPV or BmPTPD-wt were performed with anti-FLAG, anti-GP64 or anti-ORF1629 antibodies. (B) Localization of GP64 and ORF1629 in PTP-deficient BV. Western blot analysis of envelope (E) and capsid (C) fractions of BV of BmNPV, BmPTPD, and BmPTPDR were performed with anti-GP64 or anti-ORF1629 antibody.</p

PTP interacts with ORF1629 in BmNPV-infected cells.

<p>(A) A yeast two-hybrid screen was performed to identify interactions between BmNPV PTP and proteins in BmNPV-infected (12 h p.i.) BmN cells or in epidermal tissues from BmNPV-infected (2 d p.i.) 5^th instar <i>B. mori</i>. This screening identified 5 PTP-interacting clones (12h-3, 12h-11, 12h-4, 12h-16, and 2d-2) by X-gal and 3-AT assays. Clones 12h-3, 12h-11, 12h-4, and 12h-16 were derived from BmNPV-infected BmN cells whereas clone 2d-2 was derived from BmNPV-infected larval <i>B. mori</i>. A legend showing the location of positive standards and PTP-interacting clones (streaked in triplicate) is shown to the right. (B) Interaction of PTP and ORF1629 in BmNPV-infected BmN cells. BmN cells were inoculated with BmNPV (WT) or BmPTPD-wt (D-wt) at an MOI of 5 or mock-infected (mock). BmPTPD-wt expresses FLAG-tagged PTP under an authentic <i>ptp</i> promoter. At 72 h p.i., the cells were harvested and immunoprecipitated with anti-FLAG antibody, and then subjected to western blot analysis (left panels) with anti-ORF1629 antibody or anti-FLAG antibody. The right “Input” panels show western blot analysis using whole cell extracts.</p