DSpace Coleção:http://repositorio.ufc.br/handle/riufc/3472026-06-15T13:51:18Z2026-06-15T13:51:18ZInteração entre fungos endofíticos melanizados septados da caatinga e genótipos contrastantes de Vigna unguiculata [L.] Walp. sob déficit hídricoTivane, Orpa Miguelhttp://repositorio.ufc.br/handle/riufc/867472026-06-12T22:36:39Z2026-01-01T00:00:00ZTítulo: Interação entre fungos endofíticos melanizados septados da caatinga e genótipos contrastantes de Vigna unguiculata [L.] Walp. sob déficit hídrico
Autor(es): Tivane, Orpa Miguel
Abstract: Drough is one of the main environmental stresses that limit agricultural productivity, especially
in the semi-arid region of the northeast, where crops such as cowpea (Vigna unguiculata) have
great socioeconomic importance. Melanized and septate endophytic fungi (DSEs) have been
associated with plant growth promotion and the mitigation of water deficit effects, bult their
functionality in agricultural crops is still poorly understood. This study avaluated the potential
of DSE isolates native to the Caatinga to promove growth and contribute to water stress
tolerance in contrasting genotypes of V. unguiculata, Pingo-de-Ouro ,2 (PO) and Santo Inácio
(SI). Of the 14 isolated species, 14 colonized cowpea and 11 colonized corn. Among them, the
DSE2 strain was selected for showing the best effects of water stress and maintaining plant
growth. Inoculation with DSE2 resulted in a higher colonization rate under water stress,
especially in the susceptible cultivar (SI). Additionally, it promoted an increase in intrinsic
water use efficiency, with a more pronounced effect in the tolerant cultivar (PO). The water
regime was the main determining fator for changes in the leaf and root metabolome, while
inoculation with DSE2 exerted a secundary modulatory effect. However, in the root system of
the SI cultivar, the presence of DSE2 promoted more expressive metabolic reprogramming
associated with the response to water stress. The results show that native DSEs from the
Caatinga have the potential to modulate physiological and metabolic responses of
V.unguiculata under water deficit, with effects depending on the water regime, genotype, and
organ analyzed.
Tipo: Dissertação2026-01-01T00:00:00ZInvestigação da atividade de nuclease da albumina-2s (Mo-CBP3) de sementes de Moringa oleiferaSantos, Arthur Vieirahttp://repositorio.ufc.br/handle/riufc/865382026-06-02T17:27:50Z2025-01-01T00:00:00ZTítulo: Investigação da atividade de nuclease da albumina-2s (Mo-CBP3) de sementes de Moringa oleifera
Autor(es): Santos, Arthur Vieira
Abstract: The plant Moringa oleifera (Moringaceae) is present in the semi-arid region. Its seeds have a
high lipid content, and the flour obtained from its seeds is used to induce the flocculation of
solid particles in turbid waters, allowing for removal and improving water quality for human
consumption. At least three chitin-binding proteins, without chitinase activity, have been
detected and studied from moringa seeds. However, a nuclease activity seems to coexist in
one of the purified fractions of the chitin-binding proteins. This was the problem that
motivated this research. Through chitin affinity chromatography, a protein fraction with
affinity (PAC) is obtained, and this chromatographic peak was subjected to ion exchange,
giving rise to 3 characteristic peaks, with peak 3 (CM-PIII) designated as Mo-CBP3.
Preliminary studies with this sample demonstrated nucleolytic activities against plasmidial
DNA in the amount of 1,25 ug of protein and 1 ug of nucleic acid. 15% polyacrylamide gel
electrophoresis revealed 3 previously undescribed bands. Different purification approaches
were used to separate Mo-CBP3 from its contaminants: reverse phase chromatography, ultra
centrifugation filtration, and size exclusion chromatography (SEC). Size exclusion
chromatography using PAC showed the best protein recovery and presented 4 peaks, which
were subjected to electrophoresis analysis. Electrophoresis revealed the separation of the
unknown proteins from the known proteins as Mo-CBPs (Moringa oleifera chitin-binding
proteins). The SEC peaks were subjected to plasmidial DNA and RNA cleavage assays
obtained from Klebsiella pneumoniae ATCC 10031, showing activity comparable to
commercial nucleases in peak 3 (P3-SE). In summary, the refined purification by size
exclusion chromatography (SEC) was crucial to isolate the biological activity. The results
demonstrated that the P3-SE of the SEC, corresponding to the Mo-CBP3 protein, possesses
remarkable nucleolytic activity against plasmidial DNA and RNA from Klebsiella
pneumoniae. This discovery of a new activity for Mo-CBP3 expands the vast potential of
Moringa oleifera seeds as a promising source for nuclease bioprospection.
Tipo: Dissertação2025-01-01T00:00:00ZProspecção e otimização de peptídeos antimicrobianos de Nicotiana sp como alternativa aos antibióticos convencionaisMourão, Dário Ryan Arruda LopesMourão, Dário Ryan Arruda Lopeshttp://repositorio.ufc.br/handle/riufc/862162026-05-11T22:41:28Z2026-01-01T00:00:00ZTítulo: Prospecção e otimização de peptídeos antimicrobianos de Nicotiana sp como alternativa aos antibióticos convencionais
Autor(es): Mourão, Dário Ryan Arruda Lopes; Mourão, Dário Ryan Arruda Lopes
Abstract: Bacterial resistance to conventional antibiotics is one of the main challenges facing public
health, driving the search for new therapeutic strategies. In this context, antimicrobial peptides
(AMPs) stand out as promising candidates due to their structural diversity and distinct
mechanisms of action. Six natural peptides (Pep 1-6) previously identified in the floral nectar
of a species of Nicotiana, extracted, purified by chromatographic techniques, and characterized
by mass spectrometry, were evaluated for antibacterial activity against Staphylococcus aureus,
S. epidermidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa through inhibitory
concentration assays. epidermidis, Klebsiella pneumoniae, and Pseudomonas aeruginosa using
minimum inhibitory concentration (MIC) assays. Among them, only Pep6 (later named
Nicotianin-I, NI) showed inhibitory activity and, although moderate, was selected as a model
molecule for structural modifications by rational design. The modifications resulted in two
bioinspired analogues, NI-A and NI-B, with significantly higher antibacterial activity than the
precursor peptide. Mechanistically, NI-A showed greater membrane permeabilization,
especially against S. epidermidis, while NI-B induced high production of reactive oxygen
species in K. pneumoniae, associated with morphological damage. Both showed greater affinity
for the bacterial membrane, attributed to the strengthening of electrostatic interactions.
Structurally, NI-A and NI-B adopted an α-helix conformation in membrane-mimetic
environments and remained disordered in aqueous media. In hemolysis assays, NI-A showed
a concentration-dependent effect, while NI-B did not show significant hemolysis, indicating
greater selectivity. Together, the results show that the rational modification of peptides derived
from Nicotiana nectar made it possible to obtain analogues with greater antibacterial efficacy
and differentiated toxicity profiles, reinforcing their potential as prototypes for the
development of new therapies against resistant bacterial infections.
Tipo: Dissertação2026-01-01T00:00:00ZPapel funcional da família de enzimas glicolato oxidase (GOX) e catalase (CAT) em feijão-caupi (Vigna unguiculata [L.] Walp.) na resposta ao Cowpea Severe Mosaic VirusBezerra, Victor Breno Faustinohttp://repositorio.ufc.br/handle/riufc/856012026-03-31T18:34:44Z2025-01-01T00:00:00ZTítulo: Papel funcional da família de enzimas glicolato oxidase (GOX) e catalase (CAT) em feijão-caupi (Vigna unguiculata [L.] Walp.) na resposta ao Cowpea Severe Mosaic Virus
Autor(es): Bezerra, Victor Breno Faustino
Abstract: With the increase in food shortages and nutritional deficiencies, the choice of alternative
crops with relevant characteristics is important. Vigna unguiculata L. is therefore a crop
of great interest. However, cowpeas are still susceptible to some pathogens, such as the
CowPea Severe Mosaic Virus (CPSMV). Under adverse conditions, such as infection by
pathogens, one of the initial mechanisms for the stress response involves the production
of reactive oxygen species. One of these molecules is hydrogen peroxide, which has its
highest production rate related to Glycolate Oxidase (GOX), an enzyme in the
photorespiration process, but like all reactive species, its production and consumption
must be finely balanced, so there is the peroxisomal enzyme Catalase (CAT), responsible
for this control during a stress phenomenon. The aim of this study was therefore to analyse
the expression of GOX and CAT gene copies, at transcript and activity level, in response
to CPSMV. To this end, the plant specimens were inoculated with CPSMV at three time
points (16 hours, 48 hours and 144 hours). Analyses of catalase enzyme activity showed
differences between the cultivars only in the initial hours (16h), in the control conditions
of inoculated Pitiúba and Mock, possibly related to the initial response to the pathogen.
In addition, analyses using DAB (3,3'-Diaminobenzidine) staining, MDA
(Malonaldehyde) and peroxide content were used to determine the degree of oxidative
stress, again with differences only between Pitiúba Mock and inoculated at 16 and 48
hours. In addition, the expression data showed differences mainly in the VuGOX1 gene
in the Macaíbo cultivar, whose expression was induced during infection compared to the
Mock. While VuGOX2 was the gene with the highest abundance at transcript level,
showing differences between the cultivars at times of 16 and 144h, with reduced
expression in inoculated Pitiúba compared to Mock 144h. Analysis of cis-elements
showed regions that corroborate points raised in the discussion, mainly related to the
pathogen response route and the synthesis of salicylic acid (SA). Thus, it is hoped that
the results found will help breeding programmes and understanding of the resistance
phenomenon.
Tipo: Dissertação2025-01-01T00:00:00Z