E. A. Trifonova

Protection of transgenic tobacco plants expressing bovine pancreatic ribonuclease against tobacco mosaic virus

Transgenic tobacco plants (Nicotiana tabacum cv. SR1) expressing extracellular pancreatic ribonuclease from Bos taurus and characterized by an increased level of ribonuclease activity in leaf extracts were challenged with tobacco mosaic virus. The transgenic plants exhibited a significantly higher level of protection against the virus infection than the control non-transformed plants. The protection was evidenced by the absence (or significant delay) of the appearance of typical mosaic symptoms and the retarded accumulation of infectious virus and viral antigen. These results demonstrate that modulation of extracellular nuclease expression can be efficiently used in promoting protection against viral diseases.

Tobacco Transformants Bearing Antisense Suppressor of Proline Dehydrogenase Gene, Are Characterized by Higher Proline Content and Cytoplasm Osmotic Pressure

The antisense suppressor was constructed for proline dehydrogenase gene (PDH; a fragment of PDH from Arabidopsis in antisense orientation and under the control of 35S promoter of cauliflower mosaic virus, CMV). In Nicotiana tabacum SR1 tobacco transformants bearing antisense suppressor for PDH, the proline content and the cytoplasm osmotic pressure were increased. The proline content in these transformants varied, whereas cytoplasm osmotic pressure was stable, which seems to reflect complicated relationships between these characteristics of the plant cell.

Tobacco transformants expressing antisense sequence of proline dehydrogenase gene possess tolerance to heavy metals

Analysis of resistance of genetically modified tobacco plants bearing antisense suppressor of proline dehydrogenase gene and characterized with higher content of proline to elevated concentrations of heavy metals was performed. It was demonstrated that progeny of transgenic plants have high resistance to lead, nickel and cadmium ions.

Effective expression of the gene encoding an extracellular ribonuclease of Zinnia elegans in the SR1 Nicotiana tabacum plants

Complementary DNA for the extracellular RNase of Zinnia elegans was cloned under control of the cauliflower mosaic virus 35S RNA constitutive promoter and transferred into the Nicotiana tabacum SR1 plants. Primary tobacco transformants were characterized by a high level of RNase activity.

Transgenic expression of Serratia marcescens native and mutant nucleases modulates tobacco mosaic virus resistance in Nicotiana tabacum L.

Extracellular Serratia marcescens nuclease is an extremely active enzyme which non-specifically degrades RNA and DNA. Its antiviral activity was previously shown both in animals and in plants when applied exogenously. Transgenic tobacco plants (Nicotiana tabacum L. cv. SR1) expressing S. marcescens chimeric, mutant, and intracellular mutant nuclease gene variants were regenerated and challenged with tobacco mosaic virus. The transgenic plants exhibited a higher level of resistance to the virus infection than the control non-transgenic plants. The resistance was evidenced by the delay of the appearance of mosaic symptoms and the retarded accumulation of viral antigen. Thus, these results reveal that modulations of both extracellular nuclease activity and intracellular RNA/DNA binding can protect plants against viral diseases.

Evaluation of Salt Tolerance of Transgenic Tobacco Plants Bearing with P5CS1 Gene of Arabidopsis thaliana

Arabidopsis thaliana Δ1-pyrroline-5-carhoxylate synthetase 1 (P5CS1) cDNA was cloned under the control of the potent constitutive 35S RNA promoter of the cauliflower mosaic virus and transferred into genome of tobacco cv. Petit Havana SR-1 (Nicotiana tabacum L.) plants. It is shown that the constitutive level of proline in the transgenic plants T0 exceeds that of the SR1 reference line by 1.5 to 4 times. Under conditions of salt stress (200, 300 mM NaCl) T1-generation transgenic plants in early stages of development formed a large biomass, developed more quickly, and had a higher rate of root growth compared to the control, which confirms the involvement of the P5CS1 gene in molecular mechanisms of stress resistance in plants.

Silencing of the Nk1 gene in the SR1 Nicotiana tabacum plants by RNA interference

Primary transformants of SR1 Nicotiana tabacum plants with RNA interference-based silencing of the gene for extracellular ribonuclease Nk1 were obtained. It was demonstrated that the profiles of ribonuclease activities of leaf protein extracts from these plants lacked ribonuclease with electrophoretic mobility corresponding to that of the Nk1 protein. Primary transformants did not differ phenotypically from control plants. They represent a new model for investigation of the biological role of extracellular ribonucleases, including the molecular mechanisms of resistance to pathogens.

Virus-induced silencing as a method for studying gene functions in higher plants

The method of virus-induced gene silencing (VIGS) based on posttranscriptional gene silencing (PTGS) is a promising new method for the study of plant gene functions. In the current review, we analyzed works on the development and improvement of this method, including the creation of new viral constructions for different plant species, the search for new reporter genes for the control of VIGS efficiency, and the development of new, efficient methods of infection.

Transgenic Tobacco (Nicotiana tabacum SR1) Plants Expressing the Gene Coding for Serratia marcescens Nuclease

The gene coding for the secreted Serratia marcescens endonuclease was fused with the mannopine synthase promoter of Agrobacterium tumefaciens Ti plasmid and transferred to Nicotiana tabacum SR1 plants. The promoter is leaf- and root-specific. The resulting transgenic plants demonstrated elevated nuclease activity. The level of the transgene product was determined in the transgenic lines.

Molecular mechanisms of autism as a form of synaptic dysfunction

Autism spectrum disorders (ASDs) are a separate group of developmental disorders with a very large genetic component. Genetic screening has identified hundreds of mutations and other genetic variations associated with autism, and bioinformatic analysis of signaling pathways and gene networks has led to the understanding that many of these mutational changes are involved in the functioning of synapses. A synapse is a site of electrochemical communication between neurons and is a required subunit for learning and memory. Interneuronal communicative connections are plastic. The most prominent forms of synaptic plasticity are accompanied by changes in protein biosynthesis, both in the neuron body and in dendrites. Protein biosynthesis, or translation, is a finely regulated process, with the central role played by mTOR kinase (mammalian or mechanistic target of rapamycin). A mutational aberration in at least one of the links of the mTOR signaling pathway impairs the synaptic plasticity and behavior. The deregulation of local translation in dendrites is connected with the following monogenic ASDs: neurofibromatosis type 1, Noonan syndrome, Costello syndrome, Cowden syndrome, tuberous sclerosis, fragile X syndrome, and Rett syndrome (RS). The review considers the most important mutations leading to monogenic autism. The possibility of a mechanism-based treatment of certain ASDs is discussed.