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To study the effect of protein synthesis inhibition on long-term sensitization of the gill- and siphon-withdrawal reflex of Aplysia, we have developed an isolated reflex preparation in which we could expose the inhibitor to only that part of the central nervous system involved in mediating the reflex and not to the other parts of the animal's central nervous system, thus minimizing the possible systemic side effects. We have found that long-term sensitization can be obtained in the isolated gill reflex, and that this long-term process, but not the short-term process, is blocked selectively by anisomycin, a reversible inhibitor of protein synthesis. Moreover, to obtain this blockade of long-term sensitization, this drug need only be applied during the training procedure. 相似文献
13.
The dark-relaxation kinetics of variable fluorescence, Fv, in intact green leaves of Pisum stativum L. and Dolichos lablab L. were analyzed using modulated fluorometers. Fast (t1/2 = 1 s) and slow (t1/2 = 7–8 s) phases in fv dark-decay kinetics were observed; the rate and the relative contribution of each phase in total relaxation depended upon the fluence rate of the actinic light and the point in the induction curve at which the actinic light was switched off. The rate of the slow phase was accelerated markedly by illumination with far-red light; the slow phase was abolished by methyl viologen. The halftime of the fast phase of Fv dark decay decreased from 250 ms in dark-adapted leaves to 12–15 ms upon adaptation to red light which is absorbed by PSII. The analysis of the effect of far-red light, which is absorbed mainly by PSI, on Fv dark decay indicates that the slow phase develops when a fraction of QA
– (the primary stable electron acceptor of PSII) cannot transfer electrons to PSI because of limitation on the availability of P700+ (the primary electron donor of PSI). After prolonged illumination of dark-adapted leaves in red (PSII-absorbed) light, a transient. Fv rise appears which is prevented by far-red (PSI-absorbed) light. This transient fv rise reflects the accumulation of QA
– in the dark. The observation of this transient Fv rise even in the presence of the uncoupler carbonylcyanide m-chlorophenyl hydrazone (CCCP) indicates that a mechanism other than ATP-driven back-transfer of electrons to QA may be responsible for the phenomenon. It is suggested that the fast phase in Fv dark-decay kinetics represents the reoxidation of QA
– by the electron-transport chain to PSI, whereas the slow phase is likely to be related to the interaction of QA
– with the donor side of PSII.Abbreviations CCCP
carbonylcyanide m-chlorophenylhydrazone
- FO
initial fluorescence level
- Fv
variable fluorescence
- P700
primary electron donor of PSI
- PSI, II
photosystem I, II
- QA (QA
–) QB (QB
–)
primary and secondary stable electron acceptor of PSII in oxidized (reduced) state
Supported by grant B6.1/88 DST, Govt. of India. 相似文献
14.
The adult nervous system is characterized by partial or complete morphological segregation of terminals from different afferent neurons innervating the same postsynaptic target. This segregation is thought to result, in part, from competition between the afferent terminals. To explore the role of the target cell in the spatial distribution of presynaptic inputs, the sensory neurons of Aplysia were cultured either with or without a common target motor neuron. In the presence of a common target, the outgrowth from two different sensory neurons tends to occupy separate postsynaptic regions. When cultured without a target motor neuron, processes from different sensory neurons do not segregate, but rather grow freely along one another. Thus, morphological segregation of sensory outgrowth requires interaction with a target neuron and may reflect competition between presynaptic terminals for a limited number of synaptic sites on the motor neuron, or for a postsynaptic trophic factor. 相似文献
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Nuclease activity associated with the Ustilago maydis virus induced killer proteins. 总被引:1,自引:0,他引:1 下载免费PDF全文
An in vitro nuclease activity was found to be associated with the purified killer proteins of Ustilago maydis. The proteins are effective against single stranded RNA, single and double stranded DNA. Endonucleolytic activity was confirmed by cleavage of circular molecules of 0x174 and PM2. Double stranded RNA did not appear to serve as a substrate. 相似文献
17.
Killer Phenomenon in USTILAGO MAYDIS: The Organization of the Viral Genome 总被引:5,自引:0,他引:5 下载免费PDF全文
The double-stranded RNA content, the production of inactive killer protein, and the presence of virus-like particles were examined in induced nonkiller mutants and nonkiller progeny from a cross between a killer strain and a sensitive strain. A correlation between the loss of the 0.7 x 106 daltons dsRNA of the Ustilago maydis P6 virus and the lack of synthesis of the killer protein was established. In vitro and in vivo complementation between nonkiller strains provide additional support for the suggestion that the 0.7 x 106 daltons dsRNA is related to the killer function. The coding capacity of the various species of dsRNA is discussed in relation to their possible function. 相似文献
18.
Aging induced changes in photosynthetic electron transport of detached barley leaves 总被引:2,自引:0,他引:2
Primary leaf segments of 11-day-old seedlings of barley (Hordtumvulgare L. cv IB 65) were floated on distilled water in darknessat 25°C to induce senescence. This stress induced agingbrings significant loss in the total content of pigments, proteinsand nucleic acids (DNA, RNA) of the leaves and of chloroplastsisolated from the senescing leaves. Of the three macromolecularcomponents, RNA content of theisolated chloroplasts was foundmost susceptible to stress-induced aging. Loss of DCPIP Hill activity of the isolated chloroplasts couldbe correlated, in a general way, with the loss of pigments,proteins and nucleic acids of the leaves and chloroplasts isolatedfrom them. However, during the stress period, the ability ofdifferent exogenous electron donors like MnCl2 and diphenylcarbazide(DPC) to feed electrons to Photo System II (PS II) was foundto be different. MnCl2 supported photoreduction of DCPIP onlyup to the fourth day, whereas DPC sustained its ability to donateelectrons up to the seventh day of incubation of the leavesin darkness. These results suggest a sequential alteration ofthe sites in the electron-transport chain between H2O and PSII reaction centers of chloroplasts during dark-induced senescence.Kinetin not only prevented the loss of pigments and proteinsduring senescence, but also preserved the integrity of the electron-transportchain. (Received November 15, 1975; ) 相似文献
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20.
Prasanna Maruthi Podsiadla-Bialoskorska Malgorzata Mielecki Damian Ruffier Nicolas Fateh Amina Lambert Annie Fanuel Mathieu Camberlein Emilie Szolajska Ewa Grandjean Cyrille 《Glycoconjugate journal》2021,38(4):437-446
Glycoconjugate Journal - Virus-Like Particles (VLPs) have been used as immunogenic molecules in numerous recombinant vaccines. VLPs can also serve as vaccine platform to exogenous antigens, usually... 相似文献