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At least 631 records · Page 35Linked to original sources
PubMed1984

Induction by carrot allelochemicals of insecticide-metabolising enzymes in the southern armyworm (Spodoptera eridania).

Carrot foliage monoterpenes induce cytochrome P-450 up to 2.9-fold, NADPH cytochrome c (P-450) reductase up to 1.6-fold, NADPH-oxidation up to 3.8-fold, aldrin epoxidation up to 1.5-fold in southern armyworm larval midgut tissues when incorporated in their diet at 0.2% for 3 days. Stigmasterol and ergosterol did not substantially induce microsomal oxidase activities and significantly inhibited GSH S-aryltransferase activity and sulfotransferase activity. Coumarin did not substantially affect microsomal oxidase and sulfotransferase activity but is the most potent inducer of GSH S-aryltransferase activity, increasing this activity 7-fold. None of the chemicals is acutely toxic to the sixth instar larvae or affect the larval weight gain except coumarin which significantly depressed the maximal body weight attained.

Animals↗
PubMed1998

Physiological and endocrine changes associated with polydnavirus/venom in the parasitoid-host system Chelonus inanitus-Spodoptera littoralis.

As shown earlier, parasitization by the egg-larval parasitoid C. inanitus causes in its host the precocious onset of metamorphosis in the 5th instar followed by developmental arrest in the prepupal stage. Polydnavirus/venom were shown to be responsible for the developmental arrest. We investigated how polydnavirus/venom affect growth of the host larvae and found that head capsule widths were smaller from the 4th to 6th stadium and weights were lower in the 6th stadium in polydnavirus/venom-containing larvae than in non-parasitized larvae. In an attempt to identify endocrine parameters that are modified by polydnavirus/venom and might be responsible for the developmental arrest in the prepupa, we compared juvenile hormones, juvenile hormone esterase and ecdysteroids between non-parasitized and polydnavirus/venom-containing larvae from the 4th instar until pupation or developmental arrest, respectively. Obvious differences became manifest only in the 6th instar at the pupal cell formation stage, i.e. 12 days after entry of polydnavirus/venom into the host egg. Then, prothoracic glands of polydnavirus/venom-containing larvae released less ecdysteroids and ecdysteroid titres were lower than in non-parasitized larvae; this was followed by a delayed, reduced and desynchronized increase in prepupal juvenile hormones and juvenile hormone esterase and a slightly modified metabolism of ecdysone. This indicates that polydnavirus/venom affects the endocrine system of the host only after pupal commitment and that inhibition of prothoracic gland activity is the first detectable effect.

Journal Article↗
PubMed1998

Overview of parasitism associated effects on host haemocytes in larval parasitoids and comparison with effects of the egg-larval parasitoid Chelonus inanitus on its host Spodoptera littoralis.

In the first part we review the effects of larval endoparasitoids and their polydnavirus and venom on the immune system of their hosts. In all systems investigated, haemocyte spreading and encapsulation activity was reduced; in some cases effects on total (THC) or differential (DHC) haemocyte count as well as modification of haemocyte morphology and ultrastructure were also documented. In many cases polydnavirus (and venom) were shown to play a major role in abrogation of the host's immune reaction. In the second part we present the first investigation of effects of parasitism and polydnavirus/venom on the immune system of the host for an egg-larval parasitoid, Chelonus inanitus. We observed that in 4th and 5th instar larvae, i.e. 7 to 10 days after parasitization, neither haemocyte spreading and encapsulation activity, nor DHC, nor haemocyte ultrastructure were altered. After parasitization with X-ray irradiated wasps, which inject polydnavirus and venom and infertile eggs, there was no alteration of the above mentioned parameters. Nevertheless, parasitoid larvae implanted into 4th instar larvae which developed from eggs parasitized with X-ray irradiated wasps were not encapsulated, whereas co-injected latex beads were. These results show that parasitism by this egg-larval parasitoid does not generally suppress the host's immune system but that polydnavirus/venom injected at oviposition prevent, by, as yet unknown mechanisms, encapsulation of the parasitoid larva.

Journal Article↗
PubMed1999

Analysis of endoparasitoid-released proteins and their effects on host development in the system Chelonus inanitus (Braconidae)-Spodoptera littoralis (Noctuidae).

Having shown earlier that the larva of C. inanitus is essential in inducing the precocious onset of metamorphosis in polydnavirus/venom containing S. littoralis, we here analysed release of proteins by parasitoid larvae and their effects on host development. Parasitoid larvae released proteins in vivo and in vitro in a stage dependent manner. An approximately 212 kD protein was released from the mid 1st instar onwards and additional smaller proteins could be associated mainly with the 2nd and 3rd instar. When parasitoids were implanted into S. littoralis larvae, parasitoid-released proteins were seen 6 hr later. When parasitoids were removed from hosts, parasitoid-released proteins persisted in the host haemolymph for some time. Injection of antiserum against parasitoid-released proteins after removal of the parasitoid larva accelerated the disappearance of the 212 kD protein and reduced the number of larvae entering metamorphosis precociously. Repeated injections of concentrated parasitoid medium into polydnavirus/venom containing larvae caused a reduction of the head capsule width and formation of miniature 6th instar larvae; this effect was not seen in the absence of polydnavirus/venom. These observations suggest that proteins released by the parasitoid might play a role in modifying host metamorphosis in the presence of polydnavirus/venom, and the temporal appearance of the 212 kD protein makes it the most interesting candidate for being involved in such an effect.

Journal Article↗
PubMed1998

Biotransformation of (+)- and (-)-Limonene by the Larvae of Common Cutworm (Spodoptera litura).

(+)-Limonene was mixed in an artificial diet at a concentration of 1 mg/g of diet, and the diet was fed to the last instar larvae of common cutworm (Spodopteralitura). Metabolites were recovered from frass and analyzed spectroscopically. (+)-Limonene was transformed mainly to (+)-p-menth-1-ene-8,9-diol (uroterpenol) and (+)-p-mentha-1,8-dien-7-oic acid (perillic acid). Similarly, (-)-limonene was transformed mainly to (-)-p-menth-1-ene-8,9-diol (uroterpenol) and (-)-p-mentha-1,8-dien-7-oic acid (perillic acid). The results indicate that there is little difference in metabolic pathway between the (+)- and (-)-forms.

Journal Article↗
PubMed1993

Expression of feline immunodeficiency virus gag and env precursor proteins in Spodoptera frugiperda cells and their use in immunodiagnosis.

The gag and env genes of the feline immunodeficiency virus strain UT113 were cloned into a baculovirus transfer vector. The recombinant plasmids were used to create recombinant baculoviruses that expressed either the gag or the env precursor protein in insect cells (Sf9 cells). Leader sequence cleavage occurred in Sf9 cells expressing the envelope precursor, but further processing was not observed. Crude lysates of insect cells infected with the wild-type baculovirus or with the recombinant viruses were used to develop an enzyme-linked immunosorbent assay for the detection of feline immunodeficiency virus-specific antibodies in cat sera. The assay showed a higher sensitivity and specificity than immunofluorescence and Western blotting (immunoblotting).

Animals↗
PubMed1974

Replication of a nuclear polyhedrosis virus in a continuous cell culture of Spodoptera frugiperda: purification, assay of infectivity, and growth characteristics of the virus.

Nonoccluded virus, polyhedra, and occluded virus were purified from a continuous cell culture of Spodopera frugiperda infected with nuclear polyhedrosis virus. The optimal temperature for the replication and lateral transmission of infectivity for the nuclear polyhedrosis viruses (NPV) in cell culture was 27 C. End-point dilution and plaque assay procedures for the measurement of infectivity are described and compared. Dose-response data demonstrated that a single particle could initiate an infection, and the validity of the relationship of 0.7 PFU per mean tissue culture infective dose (TCID(5 0)) further substantiated the accuracy of these infectivity assays. Particle-infectious unit calculations gave a ratio of 62 to 310 nonoccluded virus particles TCID(5 0). Growth cycle and lateral transmission experiments indicated that infectious material was released from cells 12 h postinfection (p.i.) and approached a maximal titer 4 days p.i. The number of polyhedra, nonoccluded virions, and TCID(5 0) produced per cell was also presented. Typical yields of NPV produced per liter flask suggested that insect cell culture systems represent a feasible means by which the replication of these viruses could be investigated.

Cell Line↗
PubMed1991

Sequential rearrangement and nuclear polymerization of actin in baculovirus-infected Spodoptera frugiperda cells.

Proper assembly of nucleocapsids of the baculovirus Autographa californica nuclear polyhedrosis virus is prevented by cytochalasin D, a drug that interferes with actin microfilament function. To investigate the involvement of microfilaments in A. californica nuclear polyhedrosis virus replication, a fluorescence microscopy study was conducted that correlated changes in distribution of microfilaments with events in the life cycle of the virus. Tetramethylrhodamine isothiocyanate-labeled phalloidin was used to label microfilaments, and monoclonal antibody was used to label p39, the major viral capsid protein. Three microfilament arrangements were found in infected cells. During uptake of virus, thick cables were formed. These were insensitive to cycloheximide, indicating that this configuration was a rearrangement of preexisting cellular actin mediated by a component of the viral inoculum. At the time of cell rounding and before viral DNA replication, ventral aggregates of actin were observed. These were sensitive to cycloheximide but not to aphidicolin, indicating that an early viral gene mediated this actin rearrangement. Ventral aggregates did not result from the rounding process itself. Uninfected cells prerounded with colchicine did not form ventral aggregates. Cells prerounded with colchicine and then infected did form aggregates. At the time of exponential production of progency virus, microfilaments were found in the nucleus surrounding the virogenic stroma. In this area (where nucleocapsid assembly is known to take place) microfilaments colocalized with p39. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblot analysis identified p39 among proteins retained on an f-actin affinity column. We postulate that microfilaments in the nucleus provide a scaffold to position capsids for proper assembly and filling with DNA.

Actin Cytoskeleton↗
PubMed1998

Nucleotide Sequence and Characterization of the p10 Gene of Spodoptera litura Nuclear Polyhedrosis Virus.

The p10 gene was localized within the 3.0 kbp BamH I fragment of the SINPV genome. With a coding sequence of 318 nucleotides, corresponding to a protein of 105 amino acids, the p10 gene of SINPV is the longest p10 gene identified so far in NPVs. The SINPV p10 gene is also distinct in having two A/TTTGTA motifs in the promoter region. With 10 heptad repeats, the SINPV P10 protein is probably forming a relatively large coiled-coil structure. The organization of SINPV ORF552-p10 gene-ORF945 cluster is collinear with that of SpliNPV and their corresponding amino acid sequences of each ORF share high similarity. This indicates that SINPV and SpliNPV belong to a homologous baculovirus group.

Journal Article↗
PubMed1991

Differential hormone regulation of acid DNase activity in the testes and fat body of Spodoptera litura (Lepidoptera-Insecta).

Acid DNase activity in the testes and fat body is high during the early larval instars which may be correlated with the extensive cell division seen in both the tissues during these stages. The increased enzyme activity, observed in the testes of the pupal stage, might be involved in the in vivo degradation of DNA in a large number of degenerating spermatocysts which occur during this stage. Total activity of acid DNase in the fat body is highest in pupal stage. Like acid phosphatase, this enzyme may also be involved in the process of remodelling of the fat body during metamorphosis. 20-Hydroxyecdysone (20-HE) does not have any effect on acid DNase activity in the testes but it alters the enzyme activity in the fat body. Juvenile hormone-I (JH-I) has no effect on the enzyme activity in the fat body.

Animals↗