摘要:

AbstractEcdysone metabolism inPieris brassicaeeggs was revealed after injection of [3H]ecdysone into eggs. Labeled ecdysteroids were analyzed by HPLC. The metabolic fate of [3H]ecdysone is similar to that observed during postembryonic development, i.e., the larval instars and pupal instar. The ecdysone molecule is affected by hydroxylations at C‐20 and at C‐26; 26‐hydroxyecdysteroids can be further oxidized into ecdysteroid acids. In an effort to identify egg ecdysteroids, we examined the metabolism of [3H]cholesterol injected into female pharate adults to achieve long‐term labeling. In eggs, [3H]cholesterol was converted to 20‐hydroxyecdysonoic acid, ecdysonoic acid, 20‐hydroxyecdysone, and ecdysone. The rates of [3H]cholesterol incorporation into ecdysteroids increase according to the age of the eggs (from 0.06% at laying to 0.12% at hatching), while the cholesterol level remains constant throughout embryogenesis, suggesting that the embryos ofPieris brassicaecan produce ecdysteroids either from cholesterol or from apolar ecdysteroids not identified by the analytical method.Pieriseggs contain amounts of ecdysteroids which increase from 1.5 nmol/g at laying to 3.8 nmol/g

ISSN:0739-4462    

DOI:10.1002/arch.940110102

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

年代:1989

数据来源: WILEY

摘要:

AbstractControl of copulation‐enhanced protein synthesis in the accessory reproductive gland of the male grasshopper,Melanoplus sanguinipes, has been studied by measurement of in vivo incorporation of [35S]methionine into a juvenile hormone (JH)‐regulated Mr72,000 glycoprotein, long hyaline protein I (LHPI). In normal males, incorporation into LHPI was enhanced within 4 h of the commencement of mating and had increased even further when measured 24 h later. Short (15 min) copulations, in which small amounts of LHPI were discharged, stimulated incorporation into LHPI but brief genital contact did not. Neither severance of the nervi corporis allati nor allatectomy (CA−) on day 1 prevented copulation‐enhancement of incorporation into LHPI. Decapitation after 15 min of copulation also failed to prevent copulation‐enhanced incorporation into LHPI. This suggests that neither the CA nor the corpus cardiacum/brain complex is essential for the response. There was, however, a strong positive correlation between the amount of LHPI lost at copulation and the subsequent rate of incorporation into LHPI. These results suggest that control of copulation‐enhanced incorporation of amino acids into LHPI is peripheral and linked to the extent of gla

ISSN:0739-4462    

DOI:10.1002/arch.940110103

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

年代:1989

数据来源: WILEY

摘要:

AbstractWe used rapid filtration assays to determine the ion selectivity of ion gradientdriven phenylalanine uptake by brush border membrane vesicles prepared from the larval midgut of the tobacco hornworm (Manduca sexta). Phenylalanine uptake by these vesicles is stimulated by both potassium and sodium. Phenylalanine uptake by larvalM. sextamidgut brush border membrane vesicles is voltage sensitive and shows little selectivity for potassium over sodium. However, phenylalanine uptake by these vesicles is stimulated by neither rubidium nor lithium.

ISSN:0739-4462    

DOI:10.1002/arch.940110104

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

年代:1989

数据来源: WILEY

摘要:

AbstractN‐acetyltransferase activity in extracts of Malpighian tubules and cerebral ganglia fromPeriplaneta americanaL. was monitored using high performance liquid chromatography with coulometric electrochemical detection. Several potential inhibitors were tested against the tissue preparations, and the results indicate distinct differences in the nature of the enzyme derived from the two sources. The Malpighian tubule and cerebral ganglia extracts were sensitive to sulfhydryl inhibition and divalent cations, and both preparations also showed end‐product inhibition with coenzyme A. Juglone, an inhibitor of choline acetyltransferase, inhibits N‐acetyltransferase activity from both tissues; however, separate studies with choline indicate that the N‐acetylation observed in this study is not due to choline acetyltransferase. A number of phenyl, phenol, catechol and indole derivatives were tested and the results indicate that the presence of a 4‐hydroxyl group on the phenol ring enhances the capacity of phenol and catechol derivatives to inhibit N‐acetyltransferase. Demethylchlordimeform inhibits the production of N‐acetyl‐p‐Octopamine by Malpighian tubule preparations and intact tissues whereas other formamidines, BTS‐27271 and amitraz, inhibit N‐acetyl‐p‐Octopamine producti

ISSN:0739-4462    

DOI:10.1002/arch.940110105

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

年代:1989

数据来源: WILEY

摘要:

AbstractAdult female locusts were reared on wheat seedlings (experimental wheat) containing more than 97% of 9,10‐cyclopropyl sterols and Δ8‐sterols and less than 2% of Δ5‐sterols. These insects showed a dramatic decrease in their cholesterol, cholestanol and Δ7‐cholestanol content compared with control insects. These changes were more dramatic for steryl esters than for free sterols. Similar results were observed in eggs laid by the insects fed on experimental wheat. The decrease in Δ5‐, Δ0‐ and Δ7‐sterols in insects reared on experimental wheat was compensated by a marked accumulation of Δ8‐sterols and 9β, 19‐cyclopropyl sterols in the free sterol fraction and especially in the steryl ester fractions. The ecdysteroid content of eggs laid by experimental female insects was reduced by up to 80% compared with controls. These and other results suggest that the dietary 9β, 19‐cyclopropyl sterols and Δ8‐sterols cannot be used byLocustain place of Δ5‐sterols for ecdysteroid biosynthesis. To give support to this hypothesis, the experimental wheat was supplemented with various sterols before being presented to the insects immediately after the first egg laying. When cholesterol, sitosterol, or cholestanol were used as supplements, there was a complete recovery of the ecdysteroid titer in the eggs, a disappearance of 9β, 19‐cyclopropyl sterols, and a restoration of the cholesterol content in both the animals and the eggs. Stigmasterol, stigmastanol, and ergosterol were much less efficient in reversing the effects of the experimental wheat. As expected, 9β, 19‐cyclopropyl sterols were totally ineffective. These results are discussed in the light of our information on the role played by sterols in insect development and on the structural features requi

ISSN:0739-4462    

DOI:10.1002/arch.940110106

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

年代:1989

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940110107

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

年代:1989

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940110101

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

年代:1989

数据来源: WILEY