摘要:

AbstractIn the hawkmothManduca sextahigh density lipophorin from adult insects (HDLp‐A) delivers lipids to developing oocytes. During this lipid delivery HDLp‐A is taken up by the oocyte and converted to a very high density lipophorin (VHDLp), which is stored in protein storage granules (yolk bodies). A membrane‐free lysate of isolatedM. sextayolk bodies was demonstrated to contain lipoprotein lipase activity that hydrolyses the diacylglycerol of HDLp‐A. With HDLp‐A as a substrate yolk body lipophorin lipase (YBLpL) activity was shown to be maximal between pH 9 and pH 9.5. NaCl concentration was optimal between 0.7 M and 1 M. YBLpL activity required neither bovine serum albumin nor calcium ions but appeared to be stimulated by 5 mM EDTA. Diisopropyl fluorophosphate effectively inhibited YBLpL activity, indicating the presence of a serine in the active site of the enzyme. The identified lipase activity co‐eluted with lipophorins and vitellins from the yolk in the void volume of a Sephadex G‐75 gel filtration column. This observation suggests that the lipase has a Mrof more than 80,000, or that the enzyme is associated with the lipoproteins. Incubation of HDLp‐A with yolk body lysate converted HDLp‐A to two classes of higher density lipophorins. The highest density lipophorins produced during this incubation approached the density of VHDLp as it is isolated from mature eggs. The possible role of YBLpL activity in the delivery of lipids to developing oocytes is discussed. © 19

ISSN:0739-4462    

DOI:10.1002/arch.940200102

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe leaf‐cutting antsAcromyrmex octospinosuslive in symbiosis with a fungus they cultivate on leaf fragments. The symbiote forms characteristic hyphal apical swellings called “gongylidia,” which are consumed in preference to the mycelium by the ants. However, the ants also ingest fluids derived from the plant leaves they handle to make the culture substrate. The 4‐desmethylsterols of the ants were essentially (83%–94% of total 4‐desmethylsterols) Δ5,7‐sterols which were identified as ergosta‐5,7,24(28)‐trien‐3β‐ol, ergosta‐5,7‐dien‐3β‐ol, and ergosterol. These Δ5,7‐sterols were all found in the gongylidia, whereas ergosterol mainly was found in the mycelium. Some Δ5‐sterols were detected in the whole body, as well as in the expressed rectal fluid of the ants which partly contains the nonabsorbed material. However, the rectal fluid, as compared to the whole body, contained much higher amounts of Δ5‐sterols originating mainly from the plant leaves. Leaf‐cutting ants preferentially retained Δ5,7‐sterols originating from the specialized gongylidia formed by the fungal symbiote, from a mixed diet of fungal

ISSN:0739-4462    

DOI:10.1002/arch.940200103

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

年代:1992

数据来源: WILEY

摘要:

AbstractOoplasmic activities of potassium and sodium were measured with ion sensitive microelectrodes before and during the period of maximal water uptake which occurs 3–5 days after oviposition for eggs incubated at 37°C. Potassium activity increased from 84 mM in eggs before fertilization at 118 mM in eggs 1 day after fertilization (d1). Sodium activity increased from 8 mM to 29 mM over the same period. These changes exceeded those predicted from the decrease in water content (8%) during the first day after oviposition. Between d1 and d3, potassium and sodium activities decreased to values predicted on the basis of the 88% increase in egg water content. Although water content increased an additional 46% between d3 and d5, ooplasmic sodium activity remained constant at 11 mM and potassium activity increased from 64 mM to 74 mM during this time. Declines in concentrations of sodium and potassium measured in whole eggs by atomic absorption spectrometry mirrored the increase in egg water content. The results suggest that regulation of ooplasmic sodium and potassium activities is accomplished by release of these ions from internal stores, possibly the york spheres. © 1992 Wiley‐Liss

ISSN:0739-4462    

DOI:10.1002/arch.940200104

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

年代:1992

数据来源: WILEY

摘要:

AbstractThe mode of action of a diuretic hormone from pharate adultManduca Sextaheads, which triggers fluid loss inM. sextalarvae andPieris rapaeadults, was studied. In vivo, Mas‐DH (M. sextadiuretic hormone) decreased fluid absorption from larval recta, and increased levels of the second messenger cAMP in recta and Malpighian tubules (Mt) from larvae, and in fat body of larvae and adultM. sexta. In vitro, Mas‐DH triggered minor changes in fluid loss from adult Mt, but did not affect levels of cAMP in Mt from larvae, pharate adults, or adults, though it elevated cAMP levels in fat body of these stages. © 1992 Wiley‐Lis

ISSN:0739-4462    

DOI:10.1002/arch.940200105

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

年代:1992

数据来源: WILEY

摘要:

AbstractA chromoprotein responsible for the blue coloration of the hemolymph in the spined soldier bug,Podisus maculiventris(Say), was isolated and identified as lipophorin. With the exception of its blue color the lipoprotein shares similar molecular characteristics with the hemolymph lipophorins of other Hemipterans and insects of several different orders. Its ability to carry a blue chromophore, biliverdin IX γ, adds a new feature to this multifunctional lipoprotein. © 1992 Wiley‐Liss,

ISSN:0739-4462    

DOI:10.1002/arch.940200106

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

年代:1992

数据来源: WILEY

摘要:

AbstractCyanoprotein (CP) synthesis was studied in nymphal and nondiapause adult, diapause adult, and juvenile hormone (JH) treated adult bean bugs,Riptortus clavatus. Hemolymph collected from bugs injected with [35S]‐methionine was analyzed by native polyacrylamide gel electrophoresis (PAGE) and fluorography, and CP synthesis was also determined quantitatively by rocket immunoelectrophoresis of hemolymph and counting. In the nymphal stages synthesis of CP‐1, 2, 3, and 4 (with CP‐4 synthesis predominant) reached a maximum at mid‐instar and was not detected at each ecdysis, so that the synthetic activity of CPs changed cyclically in each instar. During the nymphal stages CP synthesis showed the same pattern and level in both females and males, and both diapause and nondiapause oriented bugs. In the adult stage, however, CP synthesis differed in the two sexes and nondiapause or diapause conditions. In nondiapause males CP synthesis was not detected in the adult, but in nondiapause females CP (only CP‐1) was synthesized through the reproductive stages. CP‐1 accumulated in the egg yolk together with vitellogenin. In diapause adults (both females and males) CP‐1 to 4 were synthesized at a very low rate for over 2 months and accumulated in the hemolymph. JH or JH analog (JHA) methoprene and also long day condition, which terminate diapause, switched the main CP synthesis CP‐4 to CP‐1 in females. CP synthesis in diapause males stopped after JH(A) treatment. The activities of CP synthesis, thus, changed in developmental stages, sexes, and diapause. This is an excellent system for study of specific gene expression and switching controlled by insect hormones and sex. © 19

ISSN:0739-4462    

DOI:10.1002/arch.940200107

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

年代:1992

数据来源: WILEY

摘要:

AbstractPheromone biosynthesis in the redbanded leafroller moth,Argyrotaenia velutinana, was stimulated by homogenates of the bursa copulatrix. Although pheromonotropic activity was also extractable from the ovary, the activity of pheromone biosynthesis activating neuropeptide (PBAN) or bursa extracts was not impaired in isolated abdomens by removal of the ovary. Response to the bursa extracts was dependent on the dose administered and the time of incubation. Amounts of pheromone present in adult females of different ages appeared to be correlated with the extractable amount of pheromonotropic activity from their bursa copulatrix. Decapitation did not result in the suppression of burse factor production. Homogenates of the bursa elicited similar effects in both isolated gland and isolated abdomen incubations, but the brain neuropeptide, PBAN, was less active in the former than in the latter. Bursa extracts stimulated pheromone production in isolated abdomen incubations deprived of the bursa copulatrix, but PBAN did not. Loss of activity of bursa homogenates after treatment with either pronase E or carboxypeptidase Y indicated that the pheromonotropic factor is a proteinaceous substance. The mechanism through which pheromone production is regulated in redbanded leafroller moths is discussed. © 1992 Wiley‐Liss, I

ISSN:0739-4462    

DOI:10.1002/arch.940200108

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

年代:1992

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940200101

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

年代:1992

数据来源: WILEY