摘要:

AbstractThe post‐embryonic development ofPieris brassicaecan either be continuous (under a long photoperiod) or interrupted at the pupal stage (induced by a short photoperiod); this phenomenon is termed facultative diapause. Several studies have indicated that certain brain mechanisms could be directly involved in the perception of variations in the photoperiod and could mediate some physiological effects particular to dormancy. Biogenic amines have been particularly implicated in the response to photoperiod variations and also in the regulation of development, especially in diapause induction and termination.High performance liquid chromatography with dual electrochemical detection has therefore been used to measure several biogenic amines in pupal nervous tissues at various stages of nondiapausing and diapausing development.During direct development, the levels of dopamine (DA) andN‐acetyldopamine (NADA: a DA metabolite) in brain were relatively high in 3‐day‐old pupae and at the end of pupal life (on the 8th day). Dihydroxyphenylacetic acid (another metabolite of DA) showed no variation. Serotonin was mainly observed in 2–3‐day‐old pupae but 5‐hydroxyindoleacetic acid was never detected. In young diapausing insects, similar variations of DA levels were observed even though a slight decrease of DA metabolites was noted. Serotonin appeared somewhat later (4–5 days) and attained higher levels. In late diapausing pupae, a marked increase in DA levels was observed, especially when pupae were kept at low temperature (4°C). During diapause, serotonin levels were redu

ISSN:0739-4462    

DOI:10.1002/arch.940140202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractHigh‐frequency electrical stimulation (∼20 Hz) of the lateral nerve in abdominal segments of the cricket,Teleogryllus oceanicus, caused an increase in tonus of the abdominal dorsal longitudinal muscle (DLM). This effect persisted for 1–5 min following stimulation. Application of the pentapeptide proctolin (threshold 1–10 nM) mimicked the increase in muscle tonus produced by electrical stimulation. Individual twitches were unaffected or slightly reduced by proctolin. Low‐frequency electrical stimulation (<7 Hz) of the lateral nerve counteracted a previously induced increase in muscle tonus, apparently by activation of an inhibitory motoneuron. γ‐Aminobutyric acid (GABA) mimicked the effect of low‐frequency stimulation and reduced muscle tonus. Octopamine, in concentrations of ≤0.1 mM, was inactive on the abdominal DLM when stimulated at low frequencies (0.5–2 Hz). Application of proctolin to the metathoracic DLM caused an increase in twitch amplitude but had little effect on basal tonus. In conjunction with the previously described responses of the metathoracic DLM to octopamine, these results show that the serially homologous abdominal and metathoracic DLMs have dissimilar responses to the modulators procto

ISSN:0739-4462    

DOI:10.1002/arch.940140203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe incorporation of [1‐14C]acetate into total lipids in 1‐day‐old adult pea aphids is 3.3‐fold higher than in 20‐, 22‐, and 24‐day old adults. The polar lipid fraction was the main lipid class synthesized at any age and contained primarily eighteen carbon fatty acids. While the relative mass of 18:0, 18:1 and 18:2 decreased in older aphids, the relative amount of label incorporated into these fatty acids remained constant. Myristic acid was the main fatty acid of the triacylglycerol fraction, and the relative amount of radioactivity incorporated into this fatty acid decreased in older aphids. Twenty‐day‐old aphids had 60% fewer mycetocytes than did 1‐day‐old insects. We conclude that symbionts within the mycetocytes do not appear to be involved in the synthesis of linoleic acid, while their role in the synthesis of myrist

ISSN:0739-4462    

DOI:10.1002/arch.940140204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe mechanism of oxidation of 1,2‐dehydro‐N‐acetyldopamine (dehydro NADA) was examined to resolve the controversy between our group and Andersen's group regarding the reactive species involved in β‐sclerotization. While Andersen has indicated that dehydro NADA quinone is the β‐sclerotizing agent [Andersen, 1989], we have proposed quinone methides as the reactive species for this process [Sugumaran, 1987; Sugumaran, 1988]. Since dehydro NADA quinone has not been isolated or identified till to date, we studied the enzymatic oxidation of dehydro NADA in the presence of quinone traps to characterize this intermediate. Accordingly, both N‐acetylcysteine ando‐phenylenediamine readily trapped the transiently formed dehydro NADA quinone as quinone adducts. Interestingly, when the enzymatic oxidation was performed in the presence ofo‐aminophenol or different catechols, adduct formation between the dehydro NADA side chain and the additives had occurred. The structure of the adducts is in conformity with the generation and reactions of dehydro NADA quinone methide (or its radical). This, coupled with the fact that 4‐hydroxyl or amino‐substituted quinones instantly transformed intop‐quinonoid structure, indicates that dehydro NADA quinone is only a transient intermediate and that it is the dehydro NADA quinone methide that is the thermodynamically stable product. However, since this compound is chemically more reactive due to the presence of both quinone methide and acylimine structure on it, the two side chain carbon atoms are “activated.” Based on these considerations, it is suggested that the quinone methide derived from dehydro NADA is the reactive species responsible for cross‐link formation between dehydro NADA and cuticular compo

ISSN:0739-4462    

DOI:10.1002/arch.940140205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractEffects of female wasp reproductive gland secretions, host fat body and hemolymph, and mechanical constriction of the parasitoid egg on protein synthesis were studied in eggs ofMicroplitis croceipes(Braconidae) dissected from the wasp ovary. Protein synthesis was measured by35S‐methionine incorporation in eggs held in tissue culture medium for 16 h after treatment. Synthesis was stimulated in oocytes obtained from three regions of the ovary (egg tube, reservoir, and calyx) by fat body and venom gland but not by calyx fluid. A combination of fat body, venom gland, and calyx fluid did not enhance the level of synthesis relative to that of fat body or venom gland alone. Host hemolymph inhibited protein synthesis when incubated directly with the dissected eggs but not when the eggs were collected from an artificial oviposition substrate (AOS) containing hemolymph. The inhibitory effect of the hemolymph is thought to be due to the occurrence of melanization. Mechanical constriction did not alter the rate of synthesis, confirming an earlier report that synthesis in newly deposited eggs is ongoing and is not dependent on mechanical activation during the act of oviposition. Mechanisms responsible for sustaining protein synthesis in eggs for 16 h in vitro after their exposure to host hemolymph in the AOSs or fat body and venom gland are not known. Only a small percentage (<2%) of dissected ovarial reservoir oocytes that were mechanically constricted and exposed to the venom gland, calyx fluid, and host fat body hatched in vitro. In contrast, an earlier study demonstrated that 38% of eggs oviposited by female wasps into AOSs developed and hatche

ISSN:0739-4462    

DOI:10.1002/arch.940140206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940140201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY