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Oligosaccharide processing in the expression of human plasminogen cDNA by lepidopteran insect (Spodoptera frugiperda) cells.

A comparison has been made between the Asn289-linked oligosaccharide structures of human plasma plasminogen and a recombinant human plasminogen, expressed in lepidopteran insect (Spodoptera frugiperda) cells, after infection of these cells with a recombinant baculovirus containing the entire human plasminogen cDNA. Using anion-exchange liquid chromatography mapping of the oligosaccharide units cleaved from the proteins by glycopeptidase F, compared with elution positions of standard oligosaccharide structures, coupled with monosaccharide compositional analysis, we find that the human plasma protein contained only bisialo-biantennary complex-type carbohydrate and asialo-biantennary complex carbohydrate, confirming earlier work published by this laboratory. The glycosylation pattern of the insect cell expressed recombinant human plasminogen showed considerable microheterogeneity, with identifiable high-mannose carbohydrate (Man9GlcNAc2) and truncated high-mannose oligosaccharide (Man5GlcNAc2, Man4GlcNAc2, and Man3GlcNAc2). Of major importance, approximately 40% of the oligosaccharide population consisted of complex carbohydrate (bisialo-biantennary), identical in structure with that of the human plasma protein. This is the first direct identification of complex carbohydrate in proteins produced in insect cells and demonstrates that trimming and processing of high-mannose carbohydrate into complex-type oligosaccharide can occur. Our data indicate that both normal and alternate pathways exist in these cells for incorporation and trimming of high-mannose oligosaccharides and that mannosidases, as well as galactosyl-, hexosaminidasyl-, and sialyltransferases are present, and/or can be induced, in these cells. From these observations, we conclude that amino acid sequences and/or protein conformational properties can control oligosaccharide processing events.

Animals↗

Clonal variation in the Spodoptera frugiperda IPLB-SF21-AE insect cell population.

Clones have been isolated from the heterogeneous Spodoptera frugiperda IPLB-SF21-AE insect cell population. Five of these clones, in addition to the parent cell line and the SF9 cell line (another clonal isolate of the parent cell line), have been compared in regards to morphology, growth, budded virus synthesis, and recombinant protein synthesis. No significant differences in cell morphology were found among these cell lines. There was, however, a significant difference in the average cell size, with diameters ranging from 9.30 +/- 0.184 to 11.11 +/- 0.22 microns and from 9.17 +/- 0.05 to 11.25 +/- 0.24 microns for cells growing in Excell 401 serum-free medium in spinner flask cultures and in TNM-FH medium supplemented with 10% FBS in tissue flask cultures, respectively. While no significant differences in the growth rates were found in TNM-FH medium containing 10% calf serum, significant differences were found in Excell 401 serum-free medium, with population doubling times ranging from 38.5 +/- 6.6 to 64.5 +/- 6.4 h in spinner flask studies. Significant differences in expression levels of Escherichia coli beta-galactosidase (beta-gal) were also found in both 12-well plates and spinner flasks. In the 12-well plate studies, the peak levels of beta-galactosidase obtained by these cell lines ranged from 0.332 +/- 0.091 to 0.805 +/- 0.117 mg/10(6) cells and from 0.580 +/- 0.130 to 1.458 +/- 0.132 mg/10(6) cells in Excell 401 and Hyclone Hy-Q serum-free media, respectively. In the spinner flask studies, peak expression levels ranged from 0.128 +/- 0.053 to 0.573 +/- 0.215 mg/10(6) cells in Excell 401 serum-free medium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Spodoptera exigua oviposition and larval feeding preferences for pigweed, Amaranthus hybridus, over squaring cotton, Gossypium hirsutum, and a comparison of free amino acids in each host plant.

The beet armyworm, Spodoptera exigua (Hübner), can utilize a number of different host plants for oviposition and larval development, but some host plants are preferred over others. This study, using cage choice tests and olfactometer assays, demonstrates the beet armyworm's preference for pigweed, Amaranthus hybridus L., over cotton, Gossypium hirsutum L. Cage and olfactometer choice assays indicated that olfaction plays an important role in host selection by ovipositing females. First instars exhibited no feeding preference, but the more mobile third instars showed a significant feeding preference for excised pigweed leaves. The higher quantities and more diverse accumulations of free amino acids in pigweed might, in conjunction with other physiochemical and mechanical attractant and deterrent factors in the two-plant species system, play roles in the tendency of the beet armyworm to select pigweed over cotton and in providing a superior array of easily absorbed amino acids as compared to cotton.

Amaranthus↗

Induction of volatile emissions in maize by different larval instars of Spodoptera littoralis.

Maize plants under attack by caterpillars emit a specific blend of volatiles that is highly attractive to parasitic wasps. The release of these signals is induced by elicitors in the caterpillar regurgitant. Studies suggest that plants respond differently to different herbivore species and even to different herbivore stages, thus providing parasitoids and predators with specific signals. We tested if this is the case for different larval instars of the noctuid moth Spodoptera littoralis when they feed on maize plants. Cut maize plants were incubated in diluted regurgitant from second, third, or fifth instar caterpillars. There were no differences in total amount released after these treatments, but there were small differences in the release of the minor compounds phenethyl acetate and alpha-humulene. Regurgitant of all three instars contained the elicitor volicitin. To test the effect of actual feeding by the larvae, potted plants were infested with caterpillars of one of the three instars, and volatiles were collected the following day. The intensity of the emissions was correlated with the number of larvae feeding on a plant, and with the amount of damage inflicted, but was independent of the instar that caused the damage. We also used artificial damage to mimic the manner of feeding of each instar to test the importance of physical aspects of damages for the odor emission. The emission was highly variable, but no differences were found among the different types of damage. In olfactometer tests, Microplitis rufiventris, a parasitoid that can only successfully parasitize second and early third instar S. littoralis, did not differentiate among the odors of maize plants attacked by different instar larvae. The odor analyses as well as the parasitoid's responses indicate that maize odors induced by S. littoralis provide parasitoids with poor information on the larval developmental stage. We discuss the results in the context of variability and lack of specificity in odorous plant signals.

Animals↗

Interactive effects of genotype, environment, and ontogeny on resistance of cucumber (Cucumis sativus) to the generalist herbivore, Spodoptera exigua.

Host-plant genotype, environment, and ontogeny all play a role in determining plant resistance to herbivory, yet little is known about the nature of the interactions among these factors. We investigated resistance of cucumber plants Cucumis sativus to the generalist herbivore Spodoptera exigua in a manipulative experiment involving three factors. In particular, we tested the effects of bitter (cucurbitacins present) vs. sweet (cucurbitacins absent) plants (genotype), with or without previous herbivory (environment), and cotyledons vs. true leaves (ontogeny). Contrary to our expectations, S. exigua growth was 54% higher on bitter plants than on sweet plants; growth was 63% higher, however, on undamaged plants compared to damaged plants, and 59% higher on true leaves compared to cotyledons. Moreover, all two-way interaction terms between genotype, environment, and ontogeny were significant. For example, S. exigua performance was higher on bitter than on sweet plants; however, this effect was strongly influenced by whether the tissue consumed was a cotyledon or true leaf and also whether it had been previously damaged. An examination of leaf nutritional chemistry revealed that some of our results could be explained by genotypic, environmental, and ontogenic differences in foliar nitrogen content. In contrast, the cucurbitacin content of plants did not appear to affect caterpillar growth. Our results provide evidence for the importance of interactions between genotype, environment, and ontogeny in determining herbivory and illustrate the value of manipulative experiments in revealing the complexities of these interactions.

Adaptation, Physiological↗

Expression and characterization of recombinant human alpha-3/4-fucosyltransferase III from Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tn) cells using the baculovirus expression system.

The human alpha-3/4-fucosyltransferase III (Fuc-TIII) participates in the synthesis of Lewis determinants. The enzyme from human sources is scarce and heterogeneous. In this paper we describe the expression of a secreted form of Fuc-TIII (SFT3) in two insect cell lines, Spodoptera frugiperda (Sf9) and Trichoplusia ni (Tn), using the baculovirus expression system. The Sf9 cells secreted approx. 0.4 unit/l (1 mg/l) of the enzyme. The Tn cells secreted approx. 3-fold this amount. A large proportion of active protein was accumulated in the two cell lines (50 and 75% respectively for Sf9 and Tn cells, on the fourth day after infection) indicating a possible limitation not only of the folding machinery, but also a saturation of the secretory pathway. SFT3 was purified by cation-exchange chromatography followed by affinity chromatography. The enzyme from the Tn cell line had a lower global charge, possibly due to post-translational modifications, such as phosphorylation or sulphation. The two glycosylation sites from SFT3 were occupied. SFT3 secreted by Sf9 cells was completely deglycosylated by peptide-N-glycanase F, whereas 50% of SFT3 secreted by Tn cells was resistant to deglycosylation by this enzyme. The apparent kinetic parameters determined with the type I acceptor were k(cat)=0.4 s(-1) and K(m)=0.87 mM for the SFT3 secreted by Tn cells, and k(cat)=0.09 s(-1) and K(m)=0.76 mM for the SFT3 secreted by Sf9 cells, indicating that the enzymes had substrate affinities within the same order of magnitude as their mammalian counterpart. Furthermore, SFT3 secreted by either cell type showed a clear preference for type 1 carbohydrate acceptors, similarly to human Fuc-TIII.

Amino Acid Sequence↗

Properties of 5-aminolaevulinate synthetase and its relationship to microsomal mixed-function oxidation in the southern armyworm (Spodoptera eridania).

1. Activity of 5-aminolaevulinate synthetase was measured in the midgut and other tissues of the last larval instar of the southern armyworm (Spodoptera eridania Cramer, formerly Prodenia eridania Cramer). 2. Optimum conditions for measuring the activity were established with respect to all variables involved and considerable differences from those reported for mammalian enzyme preparations were found. 3. Maximum activity (20 nmol/h per mg of protein) occurs 18-24 h after the fifth moult and thereafter decreases to trace amounts as the larvae age and approach pupation. 4. Synthetase activity was rapidly induced by oral administration (in the diet) of pentamethylbenzene, phenobarbital, diethyl 1,4-dihydro-2,4,6-trimethylpyridine-3, 5-dicarboxylate, and 2-allyl-2-isopropylacetamide. 5. Puromycin inhibited the induction of synthetase by pentamethylbenzene. 6. Induction of 5-aminolaevulinate synthetase correlated well with the induction of microsomal N-demethylation of p-chloro-N-methylaniline, except for phenobarbital, which induced the microsomal oxidase relatively more than the synthetase.

5-Aminolevulinate Synthetase↗

Purification and characterization of NADPH--cytochrome c reductase from the midgut of the southern armyworm (Spodoptera eridania).

1. NADPH-cytochrome c reductase was solubilized with bromelain and purified about 400-fold from sucrose/pyrophosphate-washed microsomal fractions from southern armyworm (Spodoptera eridania) larval midguts. 2. The enzyme has a mol.wt. of 70 035 +/- 1300 and contained 2 mol of flavin/mol of enzyme consisting of almost equimolar amounts of FMN and FAD. 3. Aerobic titration of the enzyme with NADPH caused the formation of a stable half-reduced state at 0.5 mol of NADPH/mol of flavin. 4. Kinetic analysis showed that the reduction of cytochrome c proceeded by a Bi Bi Ping Pong mechanism. 5. Apparent Km values for NADPH and cytochrome c and Ki values for NADP+ and 2'-AMP were considerably higher for the insect reductase than for the mammalian liver enzyme. 6. These are discussed in relation to possible differences in the active sites of the enzymes.

Adenosine Monophosphate↗

3'-phosphoadenosine-5'-phosphosulphate synthesis and involvement in sulphotransferase reactions in the insect, Spodoptera littoralis.

1. Synthesis of 3'-phosphoadenosine-5'-phosphosulphate from ATP and 35SO4(-2) was demonstrated by homogenates of gut. Malpighian tubules and fat body of Spodoptera littoralis. 2. The enzyme system was most active in the gut tissue, and was primarily located in the cytosol fraction of the cell. Gut cytosol preparations were used as a source of the 3'-phosphoadenosine-5'-phosphosulphate generating system for more detailed studies. 3. Maximum synthesis required an incubation mixture containing Tris/HCl buffer (pH 7.5), ATP (20 mM), MgCl2 (13.0 mM) and K2SO4 (3 mM). 4. The specific activity of 3'-phosphoadenosine-5'-phosphosulphate synthesizing activity in gut cytosol increased during development of the sixth instar larva, reaching a peak at day 4. A sudden fall in specific activity was observed in the prepupal stage. 5. 3'-Phosphoadenosine-5'-phosphosulphate formation is the rate limiting process in the overall sulphation of p-nitrophenol in the gut cytosol preparations from S. littoralis. 6. It is concluded that the properties of the sulphate-activating system in this insect are similar to those reported for vertebrates.

Adenine Nucleotides↗

Identification of ecdysonoic acid and 20-hydroxyecdysonoic acid isolated from developing eggs of Schistocerca gregaria and pupae of Spodoptera littoralis.

Ecdysonoic acid and 20-hydroxyecdysonoic acid have been purified from developing eggs of the desert locust, Schistocerca gregaria, by high performance liquid chromatography (h.p.l.c.), and their structures were determined by p.m.r. spectroscopy and fast atom bombardment mass spectrometry of the free and methyl ester derivatives. 20-Hydroxyecdysonoic acid was also characterized from Spodoptera littoralis pupae. The occurrence of both 20-hydroxyecdysonoic acid and ecdysonoic acid in Sp. littoralis pupae was also established by h.p.l.c. comparison of the 3H-labelled acids formed from [3H]ecdysone and of their methyl esters with the corresponding substances from Sch. gregaria. The significance of ecdysteroid acids as products of ecdysteroid inactivation is discussed.

Animals↗

Construction of a cDNA encoding the multifunctional animal fatty acid synthase and expression in Spodoptera frugiperda cells using baculoviral vectors.

A cDNA encoding the 2505-residue multifunctional rat fatty acid synthase has been constructed and expressed as a catalytically active protein in Spodoptera frugiperda (Sf9) cells using Autographa californica nuclear polyhedrosis virus (baculovirus). The 7.5 kb cDNA was engineered by the amplification and sequential splicing together of seven fragments contained in overlapping cDNAs that collectively spanned the entire rat fatty acid synthase coding sequence. The full-length cDNA was cloned into a baculoviral transfer vector and used together with linearized baculoviral DNA to co-transfect Sf9 cells. Recombinant viral clones were purified and identified by Western blotting. The recombinant fatty acid synthase was expressed maximally 2 days after infection of the Sf9 cells, constituting up to 20% of the soluble cytoplasm, and could be conveniently separated from the insect host fatty acid synthase by high-performance anion-exchange chromatography. The catalytic properties of the purified recombinant fatty acid synthase are indistinguishable from those of the best preparations of the natural protein obtained from rat liver. These results indicate that, in the insect cell host, all seven catalytic components of the 2505-residue recombinant fatty acid synthase fold correctly, the acyl-carrier-protein domain is appropriately phosphopantetheinylated post-translationally, and the multifunctional polypeptide forms catalytically competent dimers. Thus the baculoviral system appears to be well suited for the expression of specific fatty acid synthase mutants that can be used to explore the mechanism by which the seven domains of this multifunctional homodimer co-operate in the biosynthesis of fatty acids.

Amino Acid Sequence↗

Immunological analysis of developmental changes in ecdysone 20-mono-oxygenase expression in the cotton leafworm, Spodoptera littoralis.

The developmental changes in ecdysone 20-mono-oxygenase during the sixth larval instar of the cotton leafworm, Spodoptera littoralis, were investigated. The specific activity of mitochondrial ecdysone 20-mono-oxygenase in the fat-body exhibited a distinct peak at 72 h, at which time the larvae stop feeding. Immunoblot analyses, using antibodies raised against components of vertebrate mitochondrial steroidogenic enzyme systems [anti-(cytochrome P-450scc), anti-(cytochrome P-450(11) beta), anti-adrenodoxin and anti-(adrenodoxin reductase) antibodies], revealed the presence of specific immunoreactive polypeptides in fat-body mitochondrial extracts. In addition, these antibodies effectively inhibited fat-body mitochondrial ecdysone 20-mono-oxygenase activity. This suggests that the S. littoralis steroid-hydroxylating system(s) may contain polypeptide components analogous to those present in vertebrates. A close correlation between developmental changes in mitochondrial ecdysone 20-mono-oxygenase activity and the abundance of polypeptides (approx. 66 kDa and 50 kDa) recognized by the anti-(cytochrome P-450(11) beta) antibody and a polypeptide (approx. 52 kDa) recognized by the anti-(adrenodoxin reductase) antibody were observed in both fat-body and midgut. These results suggest that developmental changes in the abundance of components of the ecdysone 20-mono-oxygenase system may play an important role in the developmental regulation of the enzyme expression and, hence, of 20-hydroxyecdysone titre.

Adrenodoxin↗

Induction of an inactivation pathway for ecdysteroids in larvae of the cotton leafworm, Spodoptera littoralis.

Treatment of the last-instar larvae of the cotton leafworm (Spodoptera littoralis) with ecdysteroids (moulting hormones) results in the induction of an ecdysteroid-inactivation pathway. Administration of ecdysone, 20-hydroxyecdysone or an ecdysteroid agonist, RH 5849, leads to induction of an ecdysteroid 26-hydroxylase activity. This induction occurred in both early sixth-instar larvae and in older larvae which had been head-ligated to prevent the normal developmental increase in ecdysone 20-mono-oxygenase activity. The induction of 26-hydroxylase activity requires both RNA and protein synthesis, as demonstrated by experiments involving actinomycin D and cycloheximide. The 26-aldehyde derivative of ecdysone and ecdyson-26-oic acid were also formed from ecdysone in the RH 5849-induced systems. Formation of the aldehyde and the corresponding 26-oic acid (ecdysonoic acid) from 26-hydroxyecdysone was directly demonstrated in a cell-free system, thus establishing the following inactivation pathway: Ecdysteroid-->26-hydroxyecdysteroid-->ecdysteroid 26-aldehyde-->ecdysteroid 26-oic acid.

Animals↗

Improvement of the attractiveness of spodoptera littoralis sex pheromone, and its possible use in safety belts around cultivated areas to control the pest in Israel.

A comparison of the field attractiveness of five samples of American-synthesized and one sample of Japanese-synthesized (Z,E)-9,11-tetradecadien-1-01 acetate (9,11-TDDA), the sex pheromone of Spodoptera littoralis Boisd. and S. litura (F.), showed that traps baited with one of the American-produced samples and the Japanese product were equally effective in attracting and capturing S. littoralis males in cotton and alfalfa fields of Israel. Optimum captures were obtained for periods up to three months with 4800 mug of 9,11-TDDA plus 8 mg of an antioxidant; higher doses were not advantageous. Paper squares were superior to two types of rubber septa and to closed polyethylene vials as dispensers for the pheromone; the polyethylene vials were least effective. In terms of numbers of moths captured, open polyethylene vials were as effective as paper dispensers when both were baited with 9-11-TDDA plus antioxidant. Admixture of (Z,E)-9,12-tetradecadien-1-o1 acetate (9,12-TDDA) with 9,11-TDDA was antagonistic at ratios of 1:20 and 1:50, but ratios from 1:500 to 1:1600 were synergistic, increasing moth catches up to 2.5-fold. Pheromone traps placed in Caesarea sand dunes located at least 3 km from the nearest host area captured larger numbers of males than traps placed in cultivated areas. It is therefore recommended that safety belts of pheromone traps, about 500 m apart, be used around cultivated areas to prevent invasion of the pest from outside and to attract males present inside such areas, thus reducing both the male population and mating through mass trapping and disruption of sex communication.

Animals↗

The DNA contained by nuclear polyhedrosis viruses isolated from four Spodoptera spp. (Lepidoptera, Noctuidae); genome size and configuration assessed by electron microscopy.

The mol. wt. of the DNA from four nuclear polyhedrosis viruses isolated from Spodoptera littoralis, S. exempta, S. exigua and S. frugiperda were determined to be 84, 80, 68 and 74 X 10(6), respectively, by electron microscopy. The molecules were demonstrated to exist as double-stranded relaxed circular or supercoiled DNA, though linear forms of DNA were also observed.

Animals↗

The use of a protein A conjugate in an indirect enzyme-linked immunosorbent assay (ELISA) of four closely related baculoviruses from Spodoptera species.

The virus particles from four closely related insect nuclear polyhedrosis virus (NPVs) isolated from their homologous Spodoptera spp. hosts were examined using an indirect enzyme-linked immunosorbent assay (ELISA), employing both swine anti-rabbit and protein A conjugate. Results from both systems indicated that S. littoralis NPV is serologically distinct from the other three viruses, S. frugiperda NPV, S. exempta NPV and S. exigua NPV, which are closely related. The relatedness of these viruses is discussed with reference to existing knowledge and the results obtained from both conjugate systems.

Antigens, Viral↗

Baculovirus (MNPV) genomic variants: characterization of Spodoptera exempta MNPV DNAs and comparison with other Autographa californica MNPV DNAs.

A nuclear polyhedrosis virus (NPV) strain from Spodoptera exempta (SeMNPV-25 baculovirus) is a restriction endonuclease DNA map variant similar to Autographa californica NPV (AcMNPV baculovirus). Fourteen restriction endonuclease variants were identified and isolated from a SeMNPV baculovirus stock with 12 of the variants found at low frequency (less than 3%). The DNA from each variant was compared to the prototype SeMNPV-25 for insertions, deletions and new restriction sites. Regions of variation were defined on the prototype SeMNPV-25 genome, and the nature of the variation within these regions was determined. These data are discussed and compared with the existing data on other variants of AcMNPV. A comparison of the physical maps revealed that all the SeMNPV variants were different from those reported for AcMNPV. Although the SeMNPV variants were distinctive, they were clearly genomic AcMNPV variants. The regions of the baculovirus genomic variation were identified, and three separate mechanisms are suggested for their generation. Five regions (hr1 to hr5) were associated with intragenic homologous viral sequences, five regions (vI to vIII) may be associated with the insertion of DNA sequences of cellular origin, and two regions (pI and pII) were associated with mutations resulting in the addition or loss of a PstI site. Physical maps were generated for SeMNPV variant regions vI, hr2, vII and vIII.

Animals↗