摘要:

AbstractThe contribution of Na+ions to the nonsynaptic electrogenesis was studied in the larval muscle fibers of mealworm,Tenebrio molitor, using currentclamp and voltage‐clamp techniques. Na‐dependent graded responses were generated by depolarizing current stimuli in Ca2+‐free solutions. These responses were insensitive to tetrodotoxin and were blocked by Co2+. Large inward‐going currents were elicited by step depolarizations in Ca2+‐free solutions under voltage‐clamp conditions. The inward currents were totally eliminated by removal of Na+from the bathing solution. These results indicate that the calcium channel of mealworm muscle is perme

ISSN:0739-4462    

DOI:10.1002/arch.940050402

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

年代:1987

数据来源: WILEY

摘要:

AbstractLike many other Lepidoptera, fifth‐stageCalpodeslarvae have three major hemolymph proteins. Their molecular weights were estimated by 3‐15% nondenaturing polyacrylamide gel electrophoresis (N‐PAGE) as 470,000 (arylphorin; Ar), 580,000 (storage protein 2; SP2) and 720,000 (storage protein 1; SP1). Carbohydrate is associated with all three, but only Ar has lipid. The three proteins have been purified by preparative N‐PAGE and sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis. On 3‐15% SDS gels, Ar dissociated into 82,000 Mrsubunits, SP2 into 86,000 Mrsubunits, and SP1 into both 86,000 and 90,000 Mrsubunits. The 470,000 Mrprotein is identified as Ar because it is rich in aromatic amino acids. The 580,000 and 720,000 Mrproteins are rich in glycine and are called storage proteins. Electron microscopy of negatively stained preparations shows that each polymer has a different geometrical arrangement of subunits. SP1 is a cube made from eight subunits. SP2 is a hexamer in the form of a pentahedral prism. Ar is probably an octahedron made from six subunits. All three geometrical arrangements could permit the presence of a central car

ISSN:0739-4462    

DOI:10.1002/arch.940050403

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

年代:1987

数据来源: WILEY

摘要:

AbstractGlutathione, pyridine nucleotides, and lipid peroxides were measured in adult houseflies following various regimens of dye treatment and light exposure. Comparisons were made between dark control and light control flies to judge the effect of light exposure alone; between dark control and dark, dye‐treated flies to evaluate the effects of dye‐feeding in the dark; and between dark, dye‐treated and light, dye‐treated flies to measure the effect of photodynamic action. No significant effect was observed in levels of NAD+, NADH, or NADP+. However, a decrease (∼ 16.7%) in NADPH during photodynamic treatment was measured. Relatively small inductions of glutathione were observed in light controls and dark, dye‐treated flies. Depletion of both GSH and total glutathione (the sum of GSH and GSSG, expressed as GSH equivalents) occurred in light, dye‐treated flies as compared to dark, dye‐treated flies. Depletion of NADPH, when related to GSH depletion, suggested that GSH is being utilized to conjugate some products of photooxidation or that it is being directly oxidized to GSSG. However, the observation of a reduction in total glutathione also suggests that a fraction of GSH is being either oxidized to a product other than GSSG or irreversibly conjugated. No significant effects from photodynamic treatment on peroxidative potential or lipid hydroperoxide

ISSN:0739-4462    

DOI:10.1002/arch.940050404

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

年代:1987

数据来源: WILEY

摘要:

AbstractLipophorin, the protein that specifically binds juvenile hormone in the hemolymph of the Colorado potato beetle,Leptinotarsa decemlineata, is a high‐density lipoprotein of Mr∼ 574,000. Lipophorin contains 43% lipid and is composed of two apoproteins: apolipophorin I (Mr∼ 251,000) and apolipophorin II (Mr∼ 78,000). Both apoproteins contain mannose residues. Carotenoids make up a substantial part of the lipid fraction. Lipophorin constitutes about 25% of the total hemolymph proteins. Its concentration in the hemolymph (26 μM in 4‐day‐old long‐day and 40 μM in 4‐day‐old short‐day beetles) changes with different physiological conditions concomitant with changes in total protein content. Lipophorin specifically binds 10R‐juvenile hormone III with high affinity. The dissociation constant for 10R‐juvenile hormone III is 12 ± 2 nM. One lipophorin molecule contains one specific juvenile hormone‐binding site. The concentration of binding sites therefore equals tha

ISSN:0739-4462    

DOI:10.1002/arch.940050405

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

年代:1987

数据来源: WILEY

摘要:

AbstractThe major protein fraction of the larval hemolymph of the southwestern corn borer,Diatraea grandiosella, was shown to be composed of approximately six native proteins, and accounted for up to 55% of the plasma proteins. The apparent molecular weights of these proteins ranged from 350,000 to 500,000, as determined by nondenaturing electrophoresis at a neutral pH. Lower apparent molecular weights were obtained when the major protein fraction was subjected to electrophoresis at a high pH under nondenaturing conditions, indicating that these proteins dissociated under alkaline conditions. The isoelectric points of the major hemolymph proteins fell between 5.6 and 5.9. Denaturing electrophoresis and two‐dimensional electrophoresis showed that the native proteins were composed of subunits having apparent molecular weights of 78,000, 84,000, and 87,000. These subunits were the major labeled polypeptides found in the hemolymph of feeding last instar larvae 24 h after they had been injected with [3H]leucine. They were also the major polypeptides synthesized when the fat body of last instar prediapausing larvae was incubated in vitro for 4 h in Grace's medium containing [3H]leucine. Immunoelectrophoresis confirmed that the major hemolymph proteins were present in the larval fat body. In addition, these proteins were the major proteins present in the hemolymph of diapasuing larva

ISSN:0739-4462    

DOI:10.1002/arch.940050406

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

年代:1987

数据来源: WILEY

摘要:

AbstractProctolin increases the frequency and amplitude of myogenic contractions and results in a sustained contraction of the oviducts ofLocusta migratoria. The possible mode of action of proctolin receptors on this visceral muscle has been investigated. Calcium‐free saline, containing either 20 mM magnesium ions or 100 μM EGTA, inhibited myogenic contractions, lowered basal tension, and abolished all the effects of proctolin following a 20 min incubation. These effects were reversible upon washing with normal saline. Similar results were obtained with normal saline containing 10 mM cobalt ions. Nifedipine at 50 μM lowered basal tension, abolished myogenic contractions, and reduced the proctolin‐induced sustained contraction by 42‐62% at 0.5 nM proctolin and by 33‐37% at 5 nM proctolin. Similar results were obtained with 100 μM verapamil. Proctolin was still capable of eliciting considerable contractions (25‐67% of controls) in preparations depolarized with 100 mM potassium saline. The removal of calcium from the high‐potassium saline reversibly abolished the potassium‐induced contraction and reversibly blocked the action of proctolin. Nifedipine was ineffective in blocking the action of proctolin in high‐potassium saline. Neither cyclic AMP levels nor cyclic GMP levels of the lateral oviducts were elevated by proctolin in the presence of a phosphodiesterase inhibitor. The results indicate that proctolin mediates its effects via an influx of external calcium ions. This calcium appears to enter through two channels, a voltage‐dependent channel and a receptor‐operated channel. Cyclic nucleotides do not appear to be involved in the action of proctolin i

ISSN:0739-4462    

DOI:10.1002/arch.940050407

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

年代:1987

数据来源: WILEY

ISSN:0739-4462    

DOI:10.1002/arch.940050401

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

年代:1987

数据来源: WILEY