Xylostella Larvae (xylostella + larva)

Distribution by Scientific Domains

Kinds of Xylostella Larvae

  • plutella xylostella larva

  • Selected Abstracts

    N-terminal tail of a viral histone H4 encoded in Cotesia plutellae bracovirus is essential to suppress gene expression of host histone H4

    W. Gad
    Abstract An endoparasitoid wasp, Cotesia plutellae, possesses a symbiotic bracovirus (CpBV), which facilitates parasitism of a specific host, such as larvae of the diamondback moth, Plutella xylostella. A viral histone H4 (CpBV-H4) has been found in the CpBV genome and its gene product plays a role in impairing the host insect cellular immune response. Based on its high similarity to histone H4 of P. xylostella apart from its extended N-terminal tail, it has been suspected to alter host gene expression. Histone subunits were purified from parasitized P. xylostella larvae and found to contain both host and viral H4s, confirming a previous report of a possible epigenetic mode of action. Moreover, this study showed that the host H4 levels in the parasitized larvae clearly decreased during the parasitization period, whereas CpBV-H4 levels maintained a significant level without significant changes. To understand the decrease of host H4 levels, transcription levels of host H4 were monitored by quantitative reverse-transcriptase PCR (RT-PCR) and showed a significant decrease in parasitized P. xylostella larvae, whereas no significant change of the mRNA level was detected in nonparasitized larvae. This transcriptional control of host H4 expression was also observed by inducing transient expression of CpBV-H4 in nonparasitized P. xylostella. Moreover, co-injection of CpBV-H4 and its specific double-stranded RNA recovered the host H4 expression level. To identify a functional domain of CpBV-H4 involved in the transcriptional control, the extended N-terminal tail of CpBV-H4 was removed by preparing a truncated viral H4 construct in an expression vector by deleting the N-terminal tail of 38 amino acid residues and inducing its expression in nonparasitized P. xylostella larvae. The truncated CpBV-H4 clearly lost its inhibitory effects on host H4 transcription. Moreover, the presence of CpBV-H4 affects the spreading of host haemocytes by an epigenetic effect, which is at least partly restored in larvae expressing the truncated version of CpBV-H4. This study suggests that the viral H4 encoded in CpBV can alter host gene expression with its extended N-terminal tail. [source]

    Characterization of an intestinal mucin from the peritrophic matrix of the diamondback moth, Plutella xylostella

    B. L. Sarauer
    Abstract The peritrophic matrix (PM) of Plutella xylostella larvae was found to contain twelve integral and eighteen loosely associated proteins. An antiserum against Mamestra configurata integral PM proteins cross-reacted with several P. xylostella PM proteins and was used to isolate a partial cDNA encoding an insect intestinal mucin (PxIIM). PxIIM was expressed primarily in the larval midgut. The deduced protein sequence of the partial cDNA contained three potentially glycosylated, mucin-like domains and six cysteine-rich chitin-binding domains (CBDs). An additional chitin-binding domain was proposed to reside at the amino terminus of the protein based on comparison with other IIM. The organization of mucin domains and CBDs exhibited features, including an internal triplet of regularly spaced CBDs and a carboxyl terminal CBD with two additional conserved cysteine residues, that were found to be common to other lepidopteran IIMs. [source]

    Changes in hemocytes of Plutella xylostella after parasitism by Diadegma semiclausum

    Fang Huang
    Abstract We examined the changes of hemocytes in the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), due to parasitism by the endoparasitoid Diadegma semiclausum (Hymenoptera: Ichneumonidae). Necrosis of prohemocytes in different stages was observed while cell death was absent in the mature hemocytes in the parasitized larvae, which was related to the declined total hemocyte count per microliter (THC). THC in the host hemolymph declined sharply by 12,h post-parasitization and then remained at a low level. When hemocytes of the parasitized larvae were cultured in vitro, encapsulation ability was suppressed coincidently with the inhibited spreading ability; however, such effects were transient. Simultaneously, activation of the prophenoloxidae from the hemocytes was inhibited. Unlike the results of previous studies, the decrease in hemocytes, which was due to the necrosis of the prohemocytes instead of the mature hemocytes in our study, was not responsible for the impaired encapsulation. Our studies suggest that parasitism by D. semiclausum have some effects on hematopoietic regulation and on hemocyte immune reaction of P. xylostella larvae. Arch. Insect Biochem. Physiol. 2009. 2008 Wiley Periodicals, Inc. [source]

    Characterization of midgut trypsinogen-like cDNA and enzymatic activity in Plutella xylostella parasitized by Cotesia vestalis or Diadegma semiclausum

    Min Shi
    Abstract Protein digestion in insects is a result of the action of a complex of proteinases present in the midgut. In this report we describe the cloning and sequencing of a trypsin cDNA from larvae of the lepidopteran herbivore Plutella xylostella. We investigated the expression of this gene and enzymatic activity of its translation product with N -a-benzoyl-l-arginine p -nitroanilide (BApNA) as substrate in P. xylostella larvae that were either unparasitized or parasitized by Cotesia vestalis or Diadegma semiclausum parasitoids. The full cDNA sequence consisted of an open reading frame (ORF) encoding 273 amino acid residues including 23 residues of a signal peptide, and the predicted mature trypsinogen-like enzyme had a molecular mass of 26.5 kDa. The amino acid sequence of this trypsinogen-like enzyme protein and phylogenetic relationship with other published trypsin enzyme proteins suggested that it may be a new proteinase in the trypsin protein family. Parasitism of D. semiclausum did not significantly change the mRNA transcript level or BApNAase activity in host larvae. By contrast, parasitization by C. vestalis induced higher transcript levels coupled with a higher level of BApNAase activity. The BApNAase activity in the midgut of nonparasitized or parasitized P. xylostella larvae increased to a maximum level at pH 12, and the parasitism by both C. vestalis and D. semiclausum increased sensitivity of the enzyme to pH values ranging from 2 to 9.5. These parasitoid-induced changes may represent host manipulation by the developing parasitoid larva. Arch. Insect Biochem. Physiol. 2008. 2008 Wiley-Liss, Inc. [source]

    Parasitic castration of Plutella xylostella larvae induced by polydnaviruses and venom of Cotesia vestalis and Diadegma semiclausum

    Su-fen Bai
    Abstract In the present study, we used ,-ray to irradiate the female parasitoids to make wasp eggs infertile, resulting in pseudoparasitization, which allowed the analysis of maternal secretions such as polydnaviruses (PDVs) and venom in the absence of larval secretions or teratocytes by the growing parasitoids. We then investigated the spermatogenesis and components of testicular proteins of male Plutella xylostella larvae pseudoparasitized by two endoparasitoids (Cotesia vestalis and Diadegma semiclausum). The results showed that pseudoparasitism by the two endoparasitoids at the early third instar host larvae both induced smaller testes in size than those of nonparasitized host larvae. Both of them caused parasitic castration, and the degree of castration is almost as severe as in naturally parasitized hosts. This suggested that PDVs and venom played a major role in the degeneration of host testes. There are significant differences in the degree of castration induced by the two endoparasitoids, with respect to testicular growth, testicular protein concentrations, and histological changes of germ cells. Cotesia vestalis bracovirus always has a significantly stronger effect on host testicular growth and development than D. semiclausum ichnovirus. SDS-PAGE analysis indicated that synthesis of P 65 and P 67 proteins were clearly inhibited in testes of hosts that were pseudoparasitized by C. vestalis while reduction in synthesis of other proteins was not evident. Arch. Insect Biochem. Physiol. 2008. 2008 Wiley-Liss, Inc. [source]

    Aerosol infectivity of a Baculovirus to Trichoplusia ni larvae: An alternative larval inoculation strategy for recombinant protein production

    Tzyy-Rong Jinn
    Abstract The baculovirus,insect expression system is a popular tool for recombinant protein production. The standard method for infecting insect larvae with recombinant baculovirus for protein production involves either feeding occlusion bodies or injecting budded virus into the cuticle. In this study, we showed that the recombinant Autographa californica multiple nucleopolyhedrovirus (AcMNPV) at titers >108 pfu/mL efficiently infected Trichoplusia ni (T. ni) larvae through aerosol inoculation of budded virus at a pressure of 5.5 104 Pa. The dipping T. ni larvae in virus-containing solution efficiently infected them. These results indicate that surface contamination, either by aerosol or dipping, lead to infection via spiracles. The aerosol infection route for AcMNPV was restricted to T. ni and Plutella xylostella larvae, whereas Spodoptera litura and Helicoverpa armigera larvae were resistant to this inoculation process. The yields of the reporter proteins DsRed and EGFP from T. ni larvae following aerosol infection were nearly identical to those following oral feeding or injection. This alternative baculovirus infection strategy facilitates recombinant protein and virus production by insect larvae. 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source]