http://repositorio.ufc.br/handle/riufc/364 2026-06-09T22:55:17Z 2026-06-09T22:55:17Z Castro, George Meredite Cunha de http://repositorio.ufc.br/handle/riufc/86536 2026-05-29T20:11:42Z 2021-01-01T00:00:00Z

Título: Atividades de Iota-Carragenana hidrolisada: influência da massa molecular Autor(es): Castro, George Meredite Cunha de Abstract: Carbohydrates have many applications in several areas, such as food and medical. Sulfated polysaccharides, due to their chemical structure, can be recognized by enzymes or receptors of animal and plant cells to trigger responses such as anticoagulant activity or plant growth and defense. The objective of this work was to demonstrate that the activity of the sulfated polysaccharide ι-carrageenan in animal or vegetable models is directly related to its molecular mass. For this, the acid hydrolysis of this polysaccharide was carried out at a concentration of 3% (m / v) in a reaction cell under shaking and with controlled temperature. A design was elaborated using the Software Statistica with 11 independent hydrolysis experiments for the study of two factors (HCl concentration - 40 to 90 ° C - and reaction temperature - 1 to 100 mM); two response (molecular mass and viscosity) were analyzed. The 11 hydrolysates and the intact polysaccharide were analyzed by Gel Permeation Chromatography and Rheometer. Tables with result ANOVA tables, mathematical models, response surfaces and contour curves for responses were generated. After analysis, two hydrolysates and the intact polysaccharide were selected for further assays. The selected samples were subjected to characterization tests: Fourier Transform Infrared Spectroscopy and Determination of soluble proteins. They were also analyzed for their activities: Cell cytotoxicity, Antioxidant activity in vitro, Anticoagulant activity in vitro (by the methods of activated partial thromboplastin time - APTT - and prothrombin time - PT), Tail bleeding time, Plant growth and defense. After analyzing the molecular masses and viscosity, samples with 123 and 14.1 KDa and the intact ι- carrageenan (1,700 KDa) were selected for subsequent assays. This selection was made due to test ι- carrageenan activities in different order of molecule sizes. The hydrolysis process did not generate changes in the products. The samples had good purity and were considered non-toxic. The hydrolysis of ι- carrageenan promoted a reduction in the antioxidant capacity of the hydrolyzate (64.05 ± 6.11%) in comparison with a whole ι- carrageenan (78.44 ± 8.95%). For the anticoagulant activity ATPP, the longest time of activity of the hydrolysates was 257.5 ± 8.1 s for the sample with 123 KDa at the concentration of 4.0 mg / mL while the intact ι- carrageenan presenting a time of 126,6 ± 19.6 s. An increase of 7.5 times in the normal clotting time was promoted in relation to intact ι- carrageenan, which promoted an increase of 3.7 s. All sources had no PT anticoagulant activity. The sample with 123 KDa was tested at the time of tail bleeding and showed bleeding tendency at 1.0 and 2.0 mg / kg. In the experiments with Vigna unguiculata plants, the sample with 123 KDa promoted an increase in leaf area (71.12 ± 9.31 cm2) compared to the control (57.22 ± 9.62 cm2). It was observed an increase in the height of plants treated with a sample with 14.1 KDa. The sample with 123 KDa promoted an increase in the fresh weight and moisture of the the plants (22.9 ± 3.73 and 20.7 ± 3.37 g, respectively) and did not change the dry mass in relation to the control. None of the samples was able to activate the defense system of V. unguiculata against the Cowpea severe mosaic virus. Tipo: Tese

2021-01-01T00:00:00Z Santos, Maria Helena Cruz dos http://repositorio.ufc.br/handle/riufc/85896 2026-04-16T14:46:14Z 2026-01-01T00:00:00Z

Título: Desenvolvimento, caracterização e avaliação da atividade angiogênica de filmes biopoliméricos de alginato e carboximetilcelulose contendo lectina de Canavalia ensiformis Autor(es): Santos, Maria Helena Cruz dos Abstract: The formation of a functional vascular system is a recognized challenge; therefore, tissue engineering has explored chemical and physical strategies to promote neovascularization. Angiogenesis induced by biomaterials occurs predominantly through the formation of new vessels from pre-existing vascular structures, regulated by the migration, proliferation, and differentiation of endothelial cells. Techniques aimed at inducing revascularization have emerged, including natural polymers, biodegradable products capable of regenerating tissues through the interaction of their biodegradation with immune cells. Plant lectins, in turn, are capable of modulating distinct cellular responses and exhibit angiogenic potential; they are proteins or glycoproteins of non-immunological origin that recognize and reversibly bind to specific carbohydrate molecules. The objective of this work is to incorporate the lectin from Canavalia ensiformis (ConA) into alginate and carboxymethylcellulose films to promote angiogenesis pathways and induce vascularization as a therapeutic and pharmacological approach. The characterization of the films and the physicochemical tests demonstrated the efficient incorporation of the lectin into the film, as observed in the differential scanning calorimetry analysis and the FT-Raman spectra. In addition to the significantly prolonged retention capacity of ConA in the film observed by the hemagglutinating activity analysis, SEM and roughness profile assays demonstrated the adhesion capacity of the films. Angiogenic activity was confirmed by the CAM assay, and immunohistochemical assays showed an increase in the expression of the angiogenic factors TGF-β and VEGF. These results demonstrate that the biopolymers used represent an effective alternative in inducing angiogenesis, paving the way for future research in the development of therapeutic and pharmacological biopolymers. Tipo: Tese

2026-01-01T00:00:00Z Costa, Igor Rafael Sousa http://repositorio.ufc.br/handle/riufc/85557 2026-03-30T16:41:38Z 2026-01-01T00:00:00Z

Título: Plasticidade de cajueiros à baixa disponibilidade hídrica no solo: mecanismos fisiológicos, metabólicos e epigenéticos Autor(es): Costa, Igor Rafael Sousa Abstract: The cashew tree (Anacardium occidentale L.) is a highly relevant species for the Brazilian semi-arid region, which it develops under environmental conditions characterized by a combination of abiotic stresses, such as high irradiance, salinity, water deficit, and high temperatures. Adaptation to this environment involves physiological and molecular mechanisms that regulate acclimation to environmental stress. This thesis investigated the processes that support tolerance and the ability to adjust to water deficit in the cashew tree, integrating different biological levels to identify functional patterns associated with adaptation. In the first chapter, physiological, biochemical, metabolic, and molecular responses were evaluated in two contrasting cashew genotypes subjected to successive cycles of water deficit followed by rehydration. The BRS 226 genotype showed greater osmotic stability during stress, more efficient photosynthetic recovery, and greater functional adjustment capacity after repeated drought exposures. The regulation of the redox state and the progressive activation of the antioxidant system indicated physiological adjustment to recurrent stress, accompanied by extensive metabolic reorganization, with modulation of compounds associated with energy metabolism and cellular adaptation. In contrast, the CCP 09 genotype showed more restricted physiological and metabolic responses, with less recovery capacity after successive stress cycles. The differential modulation of the expression of genes associated with the stress response and the activation of markers re ated to DNA methylation during recovery suggest the participation of epigenetic mechanisms in the physiological reorganization induced by drought cycles. Taken together, the results indicate that the differential tolerance between genotypes is associated with the coordination between physiological, metabolic, and molecular adjustments in response to recurrent water stress. The second chapter investigated the epigenetic dynamics associated with a single water deficit event followed by recovery in cashew seedlings, using enzymatic sequencing of DNA methylation. Although the overall methylation profile remained relatively stable across water conditions, extensive local alterations were detected throughout the genome, indicating epigenetic reorganization associated with the plant's physiological state. These modifications were related to distinct regulatory and metabolic processes between stress and recovery phases, suggesting that DNA methylation participates in the functional modulation of the water response. The observed epigenetic variations accompanied changes in photosynthetic performance and the expression of marker genes, highlighting an association between epigenetic modulation and physiological adjustments to water deficit. In an integrated manner, the results demonstrate that the cashew tree's response to water deficit involves coordination between physiological, metabolic, and epigenetic processes that contribute to functional adjustments of metabolism and the photosynthetic apparatus during stress and recovery. These findings broaden the understanding of the regulatory mechanisms associated with the water response in tropical perennial species and provide a basis for the development of genetic improvement strategies and adaptive management under scenarios of greater climate variability. Tipo: Tese

2026-01-01T00:00:00Z Cavalcante, Francisco Lucas Pacheco http://repositorio.ufc.br/handle/riufc/85351 2026-03-16T21:42:01Z 2026-01-01T00:00:00Z

Título: Abordagem ômica integrada na investigação da aclimatação ao estresse salino induzida pela ativação do retículo endoplasmático em feijão-caupi (Vigna unguiculata [L.] Walp) Autor(es): Cavalcante, Francisco Lucas Pacheco Abstract: Salinity represents one of the main limiting factors for agricultural productivity, affecting ionic homeostasis, redox balance, metabolism, and plant growth. Although the endoplasmic reticulum (ER) is recognized as an important hub for integrating cellular signals under stress conditions, the mechanisms by which its activation can modulate salt tolerance in cowpea (Vigna unguiculata [L.] Walp.) remain incompletely understood. This thesis investigated whether the controlled stimulation of adaptive endoplasmic reticulum signaling, through transient activation of the unfolded protein response (UPR) induced by tunicamycin (TM), could function as a priming mechanism, increasing the efficiency of acclimation to salinity. Foliar application of TM was selected to induce systemic ER signaling without directly altering ion uptake by roots, allowing the controlled activation of adaptive pathways prior to salt exposure. An integrative and temporal approach was employed, combining physiological analyses, Na+ and K+ quantification, hydrogen peroxide (H2O2) determination, qPCR-based gene expression analysis of unfolded protein response (UPR) markers and ion transporters, as well as metabolomic, lipidomic, and quantitative proteomic analyses in leaves. The results demonstrated that TM priming significantly attenuated the deleterious effects of NaCl, promoting improved photosynthetic performance and enhanced plant growth. A reduction in Na+ accumulation in the shoot, greater K+ retention, and increased ionic sequestration in roots were observed, indicating improved ionic homeostasis. TM application induced a rapid and transient ER stress response, characterized by an initial increase in H2O2 and early expression of UPR-related genes, with a return to basal levels within 24 hours. Under salinity, plants previously treated with TM exhibited lower H2O2 accumulation, earlier and more efficient activation of pathways associated with ER signaling and sodium transport, as well as reduced expression of chaperones and Na+ transporters. Proteomic analysis revealed that salinity promoted broad metabolic repression, including reductions in enzymes of the Calvin cycle and glycolysis (GAPDH, triose phosphate isomerase) and in ribosomal proteins, whereas TM priming attenuated this suppression and promoted selective reinforcement of the translational machinery and proteins associated with stress adaptation. Metabolomic and lipidomic profiles indicated enhanced osmotic adjustment and membrane remodeling, reinforcing cellular stability under stress conditions. It is concluded that transient ER activation acts as a physiological preconditioning mechanism, coordinating redox regulation, proteostasis, ionic homeostasis, and metabolic reprogramming. These findings expand the understanding of the ER as a regulatory hub in plant adaptation to salt stress and highlight promising molecular targets for breeding strategies aimed at increasing cowpea resilience in salinized environments. Tipo: Tese

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