摘要:

AbstractTwenty‐six sterols were isolated from eggs, larvae, workers, and queens of the red imported fire ant,Solenopsis invictaBuren. They were identified by chromatographic (TLC, GLC, and HPLC) and spectral methods (MS and1H‐NMR). Queens possessed the most varied sterol composition (24 sterols were detected). The major sterols from queens were the doubly bioalkylated 24α‐ethyl cholest‐5‐ and 7‐en‐3β‐ols whereas the major sterol from the other developmental stages was cholesterol, a sterol which lacks a C‐24 alkyl group. From fourth instar larvae were isolated two yeasts,Candida parapsilosisandYarrowia lipolytica. Both yeasts were found to synthesize similar sterols, primarily ergosterol and zymosterol (90% of the sterol mixture). A minor sterol (approximately 12% of the total sterol mixture) detected in eggs, larvae, and workers was 24‐methyl cholesta‐5,22E‐dien‐3β‐ol (brassicasterol). Brassicasterol may have originated from ergosterol produced by the fungal endosymbiotes. The amount of sterol in each developmental stage was as follows: approximately 24 μg sterol/queen, 3 μg sterol/worker, 2 μg sterol/larvae, and 0.02 μg sterol/egg. The sterol composition of the red imported fire ant differed from that of leaf‐cutting ants previously investigated where 24‐methyl sterols of ectosymbiotic fungal origin were the major sterols detected in soldie

ISSN:0739-4462    

DOI:10.1002/arch.940290102

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

年代:1995

数据来源: WILEY

摘要:

AbstractIn the Malpighian tubules ofAcheta, the distal and middle segments are functionally and morphologically quite distinct (Spring and Kim, Mol Comp Physiol 12:130–145, 1993). Furthermore, they respond quite differently to corpora cardiaca (CC) homogenates, dibutyryl cAMP, and A23187 (Kim and Spring, J Insect Physiol 38:373–381, 1992). In this study we compared secretion by these two regions in response toAchetaandRomaleaCC extracts, syntheticManduca sextadiuretic peptide (Mas‐DP1), and the family of synthetic myotropic peptides, the achetakinins, isolated fromAcheta. BothAchetaandRomaleaCC extracts had opposite effects on the two regions: mid‐tubule secretion increased 3‐fold whereas secretion by the distal segment declined 75–80%. Mas‐DP1 increased secretion by the mid‐tubule more than 3‐fold and had no effect on the distal segment. All of the achetakinins decreased secretion by the distal tubule, with achetakinin 1 being least effective (55% inhibition) and achetakinin 5 being most effective (75% inhibition). Achetakinins 1 and 2 increased midtubule secretion by 3.7‐ and 3.3‐fold, respectively, whereas the others had no effect on this region. Regarding HPLC fractions of CC extracts, in general the more hydrophilic fractions inhibited secretion by both distal and mid‐tubules. The more hydrophobic fractions were nearly uniformly stimulatory when applied to the mid‐tubule, and either inhibited secretion or had no effect on the distal region. The possible interpretations of these data and the implications towards future research are discusse

ISSN:0739-4462    

DOI:10.1002/arch.940290103

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

年代:1995

数据来源: WILEY

摘要:

AbstractDrosophiladiaphorase‐1 (DIA‐1) is an enzyme similar to mammalian DT‐diaphorase and is inhibitied in vitro by dicoumarol. However, a ten‐fold increase in DIA‐1 activity was observed when third instarDrosophila virilislarvae were fed on a diet containing 0.1 M dicoumarol for 48 h. This induction was shown to be dose dependent and immunoprecipitation experiments with DIA‐1 antiserum demonstrated an increase in the DIA‐1 protein level in dicoumarol‐treated larvae. The induction of DIA1 by dicoumarol was found to be blocked by actinomycin D, which suggests a transcriptional mechanism of regulation. The opposite effect of dicoumarol on DIA‐1 in vitro vs. in vivo suggests that a metabolic conversion takes place after the ingestion of this compound byD. virilislarvae. © 19

ISSN:0739-4462    

DOI:10.1002/arch.940290104

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

年代:1995

数据来源: WILEY

摘要:

AbstractManduca sextafemales that were decapitated produced no pheromone during the scotophase following decapitation, indicating that they were free of pheromone biosynthesis activating neuropeptide (PBAN). When deuterated hexadecanoic or (Z)‐11‐hexadecenoic acid was applied to the sex pheromone glands of decapitated or intact females of the same age, and allowed to incubate in vivo for 24 h, deuterium labeled Δ‐11‐ and Δ‐10, 12‐unsaturated 16‐carbon fatty acids were produced in both types of females. Injection of PBAN into intact or decapitated females 23 h after application of labeled acids had no effect on the production of unsaturated labeled fatty acids. However, deuterium labeled aldehydes were produced only in females that were injected with PBAN. Therefore, in this species, PBAN activates the process by which fatty acyl precursors in the pheromone gland are converted into the pheromonal aldehydes. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United

ISSN:0739-4462    

DOI:10.1002/arch.940290105

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

年代:1995

数据来源: WILEY

摘要:

AbstractAphids are highly specialized insects that feed on the phloem‐sap of plants, the amino acid composition of which is very unbalanced. Amino acid metabolism is thus crucial in aphids, and we describe a novel investigation method based on the use of14C‐labeled amino acids added in an artificial diet. A metabolism cage for aphids was constructed, allowing for the collection and analysis of the radioactivity incorporated into the aphid body, expired as CO2, and rejected in the honeydew and exuviae. This method was applied to the study of the metabolism of eight energetic amino acids (aspartate, glutamate, glutamine, glycine, serine, alanine, proline, and threonine) in the pea aphid,Acyrthosiphon pisum. All these amino acids except threonine were subject to substantial catabolism as measured by high14CO2production. The highest turnover was displayed by aspartate, with 60% of its carbons expired as CO2. For the first time in an aphid, we directly demonstrated the synthesis of three essential amino acids (threonine, isoleucine, and lysine) from carbons of common amino acids. The synthesis of these three compounds was only observed from amino acids that were previously converted into glutamate. This conversion was important for aspartate, and lower for alanine and proline. To explain the quantitative results of interconversion between amino acids, we propose a compartmentation model with the intervention of bacterial endosymbiotes for the synthesis of essential amino acids and with glutamate as the only amino acid supplied by the insect to the symbiotes. Moreover, proline exhibited partial conversion into arginine, and it is suggested that proline is probably indirectly involved in excretory nitrogen metabolism. © 1995 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940290106

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

年代:1995

数据来源: WILEY

摘要:

AbstractVitellin (Vt) was found not to be critical to the formation or structure of yolk spheres in oocytes of the moth,Plodia interpunctella(Hübner). Vitellogenic activities of the follicular tissues were determined by visualizing the immunocytolocalization of Vt subunits (YP1 and YP3) and of a follicular epithelium yolk protein (FEYP) subunit (YP2) in ultrathin sections or in whole‐mounted tissues. Vitellogenin was detectable in the inter‐follicular epithelial cell (FC) spaces of patent, vitellogenin follicles of normal females. When the follicles entered terminal growth phase, the inter‐FC spaces closed equatorially around the follicle which excluded vitellogenin from that region. The closure of the spaces spread towards the poles in more mature follicles. Vt was immunolocalized to yolk spheres of vitellogenic and terminal growth phase oocytes. To examine the role of Vt in formation of yolk spheres, ovaries were transplanted into males. Vt was not detected in the inter‐FC spaces, vitelline membrane, or yolk spheres of follicles from transplanted ovaries developing in males. However, the FEYP subunit YP2 was detected in the Golgi apparatus and secretory vesicles of columnar FC and in the yolk spheres of the oocytes from transplanted ovaries. During the late vitellogenic period, late yolk spheres appeared in the cortical region of the oocytes. In addition, YP2 was detected in the electron‐translucent vitelline membrane of terminal growth phase follicles. We conclude that Vt is not required for the formation of yolk spheres or the electron‐translucent layer of vitelline membrane. © 1995 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United St

ISSN:0739-4462    

DOI:10.1002/arch.940290107

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

年代:1995

数据来源: WILEY

摘要:

AbstractWe examined the biophysical properties of cuticular lipids isolated from the housefly,Musca domestica. Melting temperatures (Tm) of surface lipids isolated from female houseflies decreased from 39.3 °C to 35.3 °C as the females attained sexual maturity and produced sex pheromone, whereas those prepared from males did not change with age. Lipids melted over a 10–25 °C temperature range, and their physical properties were a complex function of the properties of the component lipids. TheTmof total cuticular lipids was slightly below that of cuticular hydrocarbons (HC), the predominant lipid fraction. Hydrocarbons were further fractionated into saturated, unsaturated, and methyl‐branched components. The order of decreasingTmwas total alkanes>total HCs>methyl‐branched alkanes>alkenes. For 1‐day‐old flies, measuredTms of hydrocarbons were 1.3–5.5 °C lower thanTms calculated from a weighted average ofTms for saturated and unsaturated components. For 4‐day‐old flies, calculatedTms underestimatedTmby 11–14 °C.

ISSN:0739-4462    

DOI:10.1002/arch.940290108

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

年代:1995

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940290101

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

年代:1995

数据来源: WILEY