Chronic ionising radiation exposure is a main consequence of radioactive pollution of the environment. The development of functional genomics approaches coupled with morphological and physiological studies allows new insights into plant adaptation to life under chronic irradiation. Using morphological, reproductive, physiological, and transcriptomic experiments, we evaluated the way in which Arabidopsis thaliana natural accessions from the Chernobyl exclusion zone recover from chronic low-dose and acute high-dose γ-irradiation of seeds. Plants from radioactively contaminated areas were characterized by lower germination efficiency, suppressed growth, decreased chlorophyll fluorescence, and phytohormonal changes. The transcriptomes of plants chronically exposed to low-dose radiation indicated the repression of mobile genetic elements and deregulation of genes related to abiotic stress tolerance. Furthermore, these chronically irradiated natural accessions showed higher tolerance to acute 150 Gy γ-irradiation of seeds, according to transcriptome and phytohormonal profiles. Overall, the lower sensitivity of the accessions from radioactively contaminated areas to acute high-dose irradiation may come at the cost of their growth performance under normal conditions.
Background:Currently, the most dynamic areas in the glutamate receptor system neurobiology
are the identification and development of positive allosteric modulators (PAMs) of glutamate
ionotropic receptors. PAM-based drugs are of great interest as promising candidates for the treatment of
neurological diseases, such as epilepsy, Alzheimer's disease, schizophrenia, etc. Understanding the
molecular mechanisms underlying the biological action of natural and synthetic PAMs is a key point for
modifying the original chemical compounds as well as for new drug design.Objective:We are trying to elaborate a system of molecular functional screening of ionotropic glutamate
receptor probable PAMs.Methods:The system will be based on the radioligand - receptor method of analysis and will allow
rapid quantification of new AMPAR probable PAMs molecular activity. We plan to use a tritiumlabeled
analogue of recently elaborated ionotropic GluR probable PAM ([3H]PAM-43) as the main
radioligand.Results: Here, we characterized the specific binding of the ligand and its ability to potentiate ionotropic
GluR currents. The existence of at least two different sites of [3H]PAM-43 specific binding has been
shown. One of the above sites is glutamate-dependent and is characterized by higher affinity. “Patchclamp”
technique showed the ability of PAM-43 to potentiate ionotropic GluR currents in rat cerebellar
Purkinje neurons in a concentration-dependent manner.Conclusion:The possibility of using PAM-43 as a model compound to study different allosteric effects
of potential regulatory drugs (AMPAR allosteric regulators) was shown. [3H]PAM-43 based screening
system will allow rapid selection of new AMPAR probable PAM structures and quantification of their
molecular activity.
Plant growth response to γ-irradiation includes stimulating or inhibitory effects depending on plant species, dose applied, stage of ontogeny and other factors. Previous studies showed that responses to irradiation could depend on ABA accumulation and signaling. To elucidate the role of ABA in growth and photosynthetic responses to irradiation, lines Col-8, abi3-8 and aba3 -1 of Arabidopsis thaliana were used. Seeds were γ-irradiated using 60Co in the dose range 50-150 Gy. It was revealed that the dose of 150 Gy affected germination parameters of aba3 -1 and Col-8 lines, while abi3-8 line was the most resistant to the studied doses and even showed faster germination at early hours after γ-irradiation at 50 Gy. These results suggest that susceptibility to ABA is probably more important for growth response to γ-irradiation than ABA synthesis. The photosynthetic functioning of 16-day-old plants mainly was not disturbed by γ-irradiation of seeds, and no indication of photosystem II photoinhibition was noticed, revealing the robustness of the photosynthetic system of A. thaliana. Glutathione peroxidase activity and ABA concentrations in plant tissues were not affected in the studied dose range. These results contribute to the understanding of germination and photosynthesis fine-tuning and of mechanisms of plant tolerance to ionizing radiation.
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