THE STRINGENT RESPONSE AND ITS INVOLVEMENT IN THE REACTIONS OF BACTERIAL CELLS TO STRESS

Savijanje je danas jedan od najraširenijih postupaka obrade deformiranjem, a primjena savijanja je vrlo široka, od automobilske industrije, prehrambene, zrakoplovne industrije pa sve do brodogradnje. Ovim postupkom možemo savijati različite materijale kao što su čelik, bakar, aluminij. Najraširenija je primjena za savijanje čeličnih limova i traka te cijevi i profila. Uređaji za savijanje cijevi i profila mogu se koristiti za masovnu proizvodnju dijelova kao što su automobilske ispušne cijevi, prirubnice cijevi, profili za vođenje. Fokus u ovom radu je stavljen na savijanje dijelova velikih dimenzija. Analizom postojećih rješenja odabrane su standardne komponente stroja za savijanje, a 3D model napravljen je u programskom paketu SolidWorks. U uvodnom dijelu rada napravljena je analiza tržišta, funkcijska dekompozicija te izrada koncepta. Naglasak je stavljen na smanjenje mase uređaja te jednostavnost održavanja. Nakon toga, prikazana je konstrukcijska razrada, odabir i proračun ključnih dijelova uređaja te zaključak.Bending is today one of the most used deformation processes in the world and its application itself is very wide. From the automotive industry, food, aerospace to shipbuilding. By this method, we can bend different materials such as steel, copper, aluminium. It is the most widely applied for the bending of the steel sheets and strips or pipes and profiles. Section bending machines can be used for mass production of bent tubes, such as automotive exhaust pipes, pipe flanges, guide profiles. The primary focus of the work is on bending parts of large dimensions. After conceptualisation, the analysis and selection of the of the standard components were performed, and the 3D model was created in the SolidWorks CAD package. In the first part of the thesis, an analysis of the market is described, and functional decomposition was developed. Emphasis on conceiving was placed on the weight reduction of the machine and its easy maintenance. The second part of the thesis includes the selection and the dimensioning of the critical components of the description of the embodiment principles followed by detail design and conclusion

Protein phosphatase AP2C1 negatively regulates basal resistance and defense responses to Pseudomonas syringae

Mitogen-activated protein kinases (MAPKs) mediate plant immune responses to pathogenic bacteria. However, less is known about the cell autonomous negative regulatory mechanism controlling basal plant immunity. We report the biological role of Arabidopsis thaliana MAPK phosphatase AP2C1 as a negative regulator of plant basal resistance and defense responses to Pseudomonas syringae AP2C2, a closely related MAPK phosphatase, also negatively controls plant resistance. Loss of AP2C1 leads to enhanced pathogen-induced MAPK activities, increased callose deposition in response to pathogen-associated molecular patterns or to P. syringae pv. tomato (Pto) DC3000, and enhanced resistance to bacterial infection with Pto. We also reveal the impact of AP2C1 on the global transcriptional reprogramming of transcription factors during Pto infection. Importantly, ap2c1 plants show salicylic acid-independent transcriptional reprogramming of several defense genes and enhanced ethylene production in response to Pto This study pinpoints the specificity of MAPK regulation by the different MAPK phosphatases AP2C1 and MKP1, which control the same MAPK substrates, nevertheless leading to different downstream events. We suggest that precise and specific control of defined MAPKs by MAPK phosphatases during plant challenge with pathogenic bacteria can strongly influence plant resistance

Within and beyond the stringent response-RSH and (p)ppGpp in plants

Plant RSH proteins are able to synthetize and/or hydrolyze unusual nucleotides called (p)ppGpp or alarmones. These molecules regulate nuclear and chloroplast transcription, chloroplast translation and plant development and stress response. Homologs of bacterial RelA/SpoT proteins, designated RSH, and products of their activity, (p)ppGpp-guanosine tetra-and pentaphosphates, have been found in algae and higher plants. (p)ppGpp were first identified in bacteria as the effectors of the stringent response, a mechanism that orchestrates pleiotropic adaptations to nutritional deprivation and various stress conditions. (p)ppGpp accumulation in bacteria decreases transcription-with exception to genes that help to withstand or overcome current stressful situations, which are upregulated-and translation as well as DNA replication and eventually reduces metabolism and growth but promotes adaptive responses. In plants, RSH are nuclei-encoded and function in chloroplasts, where alarmones are produced and decrease transcription, translation, hormone, lipid and metabolites accumulation and affect photosynthetic efficiency and eventually plant growth and development. During senescence, alarmones coordinate nutrient remobilization and relocation from vegetative tissues into seeds. Despite the high conservancy of RSH protein domains among bacteria and plants as well as the bacterial origin of plant chloroplasts, in plants, unlike in bacteria, (p)ppGpp promote chloroplast DNA replication and division. Next, (p)ppGpp may also perform their functions in cytoplasm, where they would promote plant growth inhibition. Furthermore, (p)ppGpp accumulation also affects nuclear gene expression, i.a., decreases the level of Arabidopsis defense gene transcripts, and promotes plants susceptibility towards Turnip mosaic virus. In this review, we summarize recent findings that show the importance of RSH and (p)ppGpp in plant growth and development, and open an area of research aiming to understand the function of plant RSH in response to stress

CRISPR/Cas-mediated plant genome editing: outstanding challenges a decade after implementation

The discovery of the CRISPR/Cas genome-editing system has revolutionized our understanding of the plant genome. CRISPR/Cas has been used for over a decade to modify plant genomes for the study of specific genes and biosynthetic pathways as well as to speed up breeding in many plant species, including both model and non-model crops. Although the CRISPR/Cas system is very efficient for genome editing, many bottlenecks and challenges slow down further improvement and applications. In this review we discuss the challenges that can occur during tissue culture, transformation, regeneration, and mutant detection. We also review the opportunities provided by new CRISPR platforms and specific applications related to gene regulation, abiotic and biotic stress response improvement, and de novo domestication of plants.ISSN:1360-1385ISSN:1878-437

MAPK Phosphatase AP2C3 Induces Ectopic Proliferation of Epidermal Cells Leading to Stomata Development in Arabidopsis

In plant post-embryonic epidermis mitogen-activated protein kinase (MAPK) signaling promotes differentiation of pavement cells and inhibits initiation of stomata. Stomata are cells specialized to modulate gas exchange and water loss. Arabidopsis MAPKs MPK3 and MPK6 are at the core of the signaling cascade; however, it is not well understood how the activity of these pleiotropic MAPKs is constrained spatially so that pavement cell differentiation is promoted only outside the stomata lineage. Here we identified a PP2C-type phosphatase termed AP2C3 (Arabidopsis protein phosphatase 2C) that is expressed distinctively during stomata development as well as interacts and inactivates MPK3, MPK4 and MPK6. AP2C3 co-localizes with MAPKs within the nucleus and this localization depends on its N-terminal extension. We show that other closely related phosphatases AP2C2 and AP2C4 are also MAPK phosphatases acting on MPK6, but have a distinct expression pattern from AP2C3. In accordance with this, only AP2C3 ectopic expression is able to stimulate cell proliferation leading to excess stomata development. This function of AP2C3 relies on the domains required for MAPK docking and intracellular localization. Concomitantly, the constitutive and inducible AP2C3 expression deregulates E2F-RB pathway, promotes the abundance and activity of CDKA, as well as changes of CDKB1;1 forms. We suggest that AP2C3 downregulates the MAPK signaling activity to help maintain the balance between differentiation of stomata and pavement cells