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  • 1
    Electronic Resource
    Electronic Resource
    Incorporation of L-canavanine into proteins and the expression of its antimetabolic effects (1991)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 39 (1991), S. 987-990 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00005a037
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  • 2
    Electronic Resource
    Electronic Resource
    Degradation of aberrant proteins by larval tobacco hornworm, Manduca sexta L. (Sphingidae) (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 8 (1988), S. 165-172 
    Details
    ISSN: 0739-4462
    Keywords: L-canavanine ; plant-insect interactions ; canavanyl protein ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The tobacco hornworm Manduca sexta (Sphingidae) readily incorporates L-canavanine, the L-2-amino-4-(guanidinooxy)butyric acid structural analog of L-arginine, into newly synthesized proteins. As a result, the developing fifth-instar larva produces structurally aberrant canavanyl proteins that can exhibit severely impaired function. This situation is exacerbated by canavanine's ability to stimulate de novo protein synthesis. M. sexta larvae can respond to anomalous protein production by degrading canavanyl proteins nearly five times faster than normal proteins. The proteases of this insect can distinguish between normal and anomalous proteins and thereby avoid destruction of essential macromolecules. Aberrant protein degradative activity is not dependent upon de novo protein synthesis induced by canavanyl proteins. The fat body appears to be the source of proteases that degrade aberrant proteins; degradation is curtailed in the presence of sulfhydryl protease inhibitors as well as inhibitors of trypsin-like activity.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940080303
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  • 3
    Electronic Resource
    Electronic Resource
    Evaluation of teratocyte functions: An overview (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 13 (1990), S. 159-166 
    Details
    ISSN: 0739-4462
    Keywords: parasitoid-host interactions ; in vitro techniques ; serosa ; polar bodies ; trophamnion ; Braconidae ; Trichogrammatidae ; Scelionidae ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Teratocytes, derived from extra-embryonic tissues of parasitic Braconidae, Trichogrammatidae, and Scelionidae, play several important roles in the parasitoid-host interaction. It is clear from the literature that the specific role (s) vary among species. Only recently have the biochemical and endocrinological roles of these cells been considered. This overview examines the recent literature on teratocytes and stresses the importance of in vitro procedures to elucidate the functional roles (trophic, immunosuppression, secretory) of teratocytes in the parasitoid-host relationship.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940130303
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  • 4
    Electronic Resource
    Electronic Resource
    Contributing factors to reduced ecdysteroid titers in Heliothis virescens parasitized by Microplitis croceipes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 13 (1990), S. 29-39 
    Details
    ISSN: 0739-4462
    Keywords: prothoracic gland ; JH esterase ; PTTH ; ecdysone 20-monooxygenase ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Heliothis virescens parasitized by Microplitis croceipes stop development at a predictable point prior to parasite emergence. The objectives of this study were to examine several factors which might contribute to the syndrome by comparing parasitized and nonparasitized larvae at specific and correspondingly similar physiological points in their development. Fifth stadium nonparasitized larvae experience a small pupal commitment burst of ecdysone followed by a large burst. In contrast, ecdysteroid titers in parasitized larvae remained at the pupal commitment level during the entire 5th stadium. Data shows that ecdysone 20-monooxygenase and sterol precursors are not limiting factors, with the possible exception of limited hemolymph sterol at the end of parasitoid development. In addition, isolated prothoracic glands from parasitized larvae produce amounts of ecdysteroid comparable to controls when stimulated with a crude Manduca sexta prothoracicotropic hormone preparation. Juvenile hormone esterase titers in parasitized larvae are low throughout the 5th stadium. They do not show the major rapid increase in activity normally associated with the latter part of the active feeding period in the nonparasitized 5th instar. Possible explanations for the low ecdysteroid titers in parasitized larvae include failure to synthesize and release prothoracic gland stimulatory factor by the poorly developed fat body, insufficient sterol precursors at the critical time of ecdysteroid synthesis, inhibition of the release of PTTH, failure of the prothoracic gland to respond to PTTH, and the consequences of abnormally high juvenile hormone titers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940130104
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  • 5
    Electronic Resource
    Electronic Resource
    Polydnavirus of Microplitis croceipes prolongs the larval period and changes hemolymph protein content of the host, Heliothis virescens (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 28 (1995), S. 33-48 
    Details
    ISSN: 0739-4462
    Keywords: tobacco budworm ; parasitoid ; Braconidae ; Noctuidae ; Hymenoptera ; Lepidoptera ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Polydnaviruses from certain parasitoid Hymenoptera have been reported to interfere with both host immunity and host development. Heliothis virescens larvae injected with either calyx fluid or sucrose gradient-purified polydnavirus from Microplitis croceipes (McPDV) gained less weight than saline-injected larvae. The active feeding portion of the fifth stadium larva (time to reach the burrowing-digging stage) was doubled (7.0 vs. 3.4 days) when a 0.25 wasp equivalent (WE) of sucrose gradient-purified McPDV was injected into a newly ecdysed fifth stadium host. Many of the treated larvae were unable to pupate, successfully and died at a point of incomplete larval-pupal ecdysis. Pupae that did result from the treated larvae weighed significantly less than controls, even at 0.025 WE. The rate of weight gain and extent of delay of development were dose-dependent; as little as 0.1 WE extended the time of active feeding by 1.5 days and yielded only 25% adults. A 0.05 WE dose yielded 78% adults compared to 95% for controls. The total protein content of hemolymph from individuals injected with McPDV was significantly less than that of controls at any McPDV dose equal to or greater than 0.1 WE. SDS-PAGE profiles of hemolymph proteins from control and McPDV-injected larvae revealed a marked inhibition of the normal accumulation of storage proteins during the fifth stadium and a lesser reduction of serine protease inhibitor protein. Thus, McPDV-injected larvae exhibited some symptoms (less total hemolymph protein and reduced amounts of storage protein) similar to those shown by both parasitized larvae and by larvae injected with M. croceipes teratocytes. However, McPDV affected development during the active feeding stage of the larva, while teratocytes primarily impacted larvae at the time when larval-pupal transformation processes are initiated. © 1995 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940280104
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  • 6
    Electronic Resource
    Electronic Resource
    Juvenile hormone esterase activity and ecdysteroid titer in Heliothis virescens larvae injected with Microplitis croceipes teratocytes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Archives of Insect Biochemistry and Physiology 20 (1992), S. 231-242 
    Details
    ISSN: 0739-4462
    Keywords: tobacco budworm ; parasitoid ; ecdysteroids ; Braconidae ; Noctuidae ; Chemistry ; Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Juvenile hormone esterase (JHE) activity in the hemolymph of 5th-instar Heliothis virescens larvae injected with Microplitis croceipes teratocytes was inversely related to the number of teratocytes injected. JHE activity in the hemolymph of larvae injected with 750 3-day-old teratocytes (the approximate number from one parasitoid embryo) was depressed to less than 5% of those levels found in control larvae. During the latter portion of the digging stage and in the burrowing-digging (BD) stage JHE activity in larvae treated with 350 teratocytes was approximately 40% of control values. However, injection of 180 teratocytes did not significantly affect JHE titers. Two-day-old teratocytes caused the greatest reduction in JHE titer with decreasing effects observed with injections of 3- to 6-day-old teratocytes. Nevertheless, because 2-day-old teratocytes were difficult to separate from host hemocytes, 3-day-old teratocytes were used in most of these studies. Injections of nonparasitized H. virescens hemolymph plasma, Micrococcus luteus bacterial cell walls, washed M. croceipes eggs, or teratocytes from Cotesia congregata did not depress JHE titers. Teratocyte injections also significantly reduced growth of host fat body. Ecdysteroid titers in cell formation, day 2 (CF2) larvae injected as new 5th instars with 350 3-day-old teratocytes failed to increase, as compared to noninjected and saline-injected controls. An injection of 1 μg/larva of 20-hydroxyecdysone at the BD stage permitted normal pupation in 50% of the teratocyte-treated larvae as compared to 0% pupation for teratocyte-treated control larvae not treated with 20-hydroxyecdysone. Teratocytes seem to be responsible for the inhibition of JHE release and thus indirectly impact on ecdysteroid titers. © 1992 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/arch.940200307
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