Identification of Potential New Genes Related to the SREBP Pathway in Xanthophyllomyces dendrorhous.

The sterol regulatory element-binding protein (SREBP) pathway is an integral cellular mechanism that regulates lipid homeostasis, in which transcriptional activator SREBPs regulate the expression of various genes. In the carotenogenic yeast Xanthophyllomyces dendrorhous, Sre1 (the yeast SREBP homolog) regulates lipid biosynthesis and carotenogenesis, among other processes. Despite the characterization of several components of the SREBP pathway across various eukaryotes, the specific elements of this pathway in X. dendrorhous remain largely unknown. This study aimed to explore the potential regulatory mechanisms of the SREBP pathway in X. dendrorhous using the strain CBS.cyp61- as a model, which is known to have Sre1 in its active state under standard culture conditions, resulting in a carotenoid-overproducing phenotype. This strain was subjected to random mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG), followed by a screening methodology that focused on identifying mutants with altered Sre1 activation phenotypes. Single-nucleotide polymorphism (SNP) analysis of 20 selected mutants detected 5439 single-nucleotide variants (SNVs), narrowing them down to 1327 SNPs of interest after a series of filters. Classification based on SNP impact identified 116 candidate genes, including 49 genes with high impact and 68 genes with deleterious moderate-impact mutations. BLAST, InterProScan, and gene ontology enrichment analyses highlighted 25 genes as potential participants in regulating Sre1 in X. dendrorhous. The key findings of this study include the identification of genes potentially encoding proteins involved in protein import/export to the nucleus, sterol biosynthesis, the ubiquitin-proteasome system, protein regulatory activities such as deacetylases, a subset of kinases and proteases, as well as transcription factors that could be influential in SREBP regulation. These findings are expected to significantly contribute to the current understanding of the intricate regulation of the transcription factor Sre1 in X. dendrorhous, providing valuable groundwork for future research and potential biotechnological applications.

Enhancing Phosphate Uptake and Antifungal Activity in Tomato Plants via Bacillus licheniformis Mutagenesis: Evaluating Growth Parameters.

The objective of the investigation was to improve phosphate solubilization in tomato plants by Bacillus licheniformis, a rhizobacterium that promotes plant growth. Ultraviolet (UV) radiation, Ethyl methanesulfonate (EMS) and Ethidium bromide (EtBr) mutagenesis produced twenty-one mutants. Phosphate solubilization was higher in the PM7 (physical mutant) (121.00 g mL-1) than in the wild type (82.00 g mL-1). PM7 showed high antifungal activity against Phytophthora capsici, Fusarium oxysporum and Dematophora necatrix besides increased siderophore production and HCN production. In a net-house experiment, PM7 improved root and shoot parameters, P assimilation and soil P availability in tomato plants. This study demonstrates the potential of PM7 as an effective rhizobacterium for enhancing nutrient availability and plant growth.

Chlorella vulgaris-mediated bioremediation of food and beverage wastewater from industries in Mexico: Results and perspectives towards sustainability and circular economy.

The food and beverage industries in Mexico generate substantial effluents, including nejayote, cheese-whey, and tequila vinasses, which pose significant environmental challenges due to their extreme physicochemical characteristics and excessive organic load. This study aimed to assess the potential of Chlorella vulgaris in bioremediating these complex wastewaters while also producing added-value compounds. A UV mutagenesis treatment (40 min) enhanced C. vulgaris adaptability to grow in the effluent conditions. Robust growth was observed in all three effluents, with nejayote identified as the optimal medium. Physicochemical measurements conducted pre- and post-cultivation revealed notable reductions of pollutants in nejayote, including complete removal of nitrogen and phosphates, and an 85 % reduction in COD. Tequila vinasses exhibited promise with a 66 % reduction in nitrogen and a 70 % reduction in COD, while cheese-whey showed a 17 % reduction in phosphates. Regarding valuable compounds, nejayote yielded the highest pigment (1.62 mg·g-1) and phenolic compound (3.67 mg·g-1) content, while tequila vinasses had the highest protein content (16.83 %). The main highlight of this study is that C. vulgaris successfully grew in 100 % of the three effluents (without additional water or nutrients), demonstrating its potential for sustainable bioremediation and added-value compound production. When grown in 100 % of the effluents, they become a sustainable option since they don't require an input of fresh water and therefore do not contribute to water scarcity. These findings offer a practical solution for addressing environmental challenges in the food and beverage industries within a circular economy framework.

In Vitro Gamma Mutagenesis Techniques in Rice (Oryza sativa L. var. Lazarroz FL).

Gamma radiation (60Co)-induced mutagenesis offers an alternative to develop rice lines by accelerating the spontaneous mutation process and increasing the pool of allelic variants available for breeding. Ionizing radiation works by direct or indirect damage to DNA and subsequent mutations. The technique can take advantage of in vitro protocols to optimize resources and accelerate the development of traits. This is achieved by exposing mutants to a selection agent of interest in controlled conditions and evaluating large numbers of plants in reduced areas. This chapter describes the protocol for establishing gamma radiation dosimetry and in vitro protocols for optimization at the laboratory level using seeds as the starting material, followed by embryogenic cell cultures, somatic embryogenesis, and regeneration. The final product of the protocol is a genetically homogeneous population of Oryza sativa that can be evaluated for breeding against abiotic and biotic stresses.

Protocols for Building and Producing High Diversity Peptide Phage Display Libraries.

Phage display is an important technology to study protein-protein interaction and protein evolution, with applications in basic science and applied biotechnology, such as drug discovery and the development of targeted therapies. However, in order to be successful during a phage display screening, it is paramount to have good phage libraries. Here, we described detailed procedures to generate peptide phage display libraries with high diversity and billions of transformants.

Understanding the Structural Requirements of Peptide-Protein Interaction and Applications for Peptidomimetic Development.

Protein-protein interaction is at the heart of most biological processes, and small peptides that bind to protein binding sites are resourceful tools to explore and understand the structural requirements for these interactions. In that sense, phage display is a well-suited technology to study protein-protein interactions, as it allows for unbiased screening of billions of peptides in search for those that interact with a protein binding domain. Here, we will illustrate how two distinct but complementary approaches, phage display and nuclear magnetic resonance (NMR), can be utilized to unveil structural details of peptide-protein interaction. Finally, knowledge derived from phage mutagenesis and NMR studies can be streamlined for quick peptidomimetic design and synthesis using the retroinversion approach to validate using in vitro and in vivo assays the therapeutic potential of peptides identified by phage display.

Bacillus subtilis stress-associated mutagenesis and developmental DNA repair.

SUMMARYThe metabolic conditions that prevail during bacterial growth have evolved with the faithful operation of repair systems that recognize and eliminate DNA lesions caused by intracellular and exogenous agents. This idea is supported by the low rate of spontaneous mutations (10-9) that occur in replicating cells, maintaining genome integrity. In contrast, when growth and/or replication cease, bacteria frequently process DNA lesions in an error-prone manner. DNA repairs provide cells with the tools needed for maintaining homeostasis during stressful conditions and depend on the developmental context in which repair events occur. Thus, different physiological scenarios can be anticipated. In nutritionally stressed bacteria, different components of the base excision repair pathway may process damaged DNA in an error-prone approach, promoting genetic variability. Interestingly, suppressing the mismatch repair machinery and activating specific DNA glycosylases promote stationary-phase mutations. Current evidence also suggests that in resting cells, coupling repair processes to actively transcribed genes may promote multiple genetic transactions that are advantageous for stressed cells. DNA repair during sporulation is of interest as a model to understand how transcriptional processes influence the formation of mutations in conditions where replication is halted. Current reports indicate that transcriptional coupling repair-dependent and -independent processes operate in differentiating cells to process spontaneous and induced DNA damage and that error-prone synthesis of DNA is involved in these events. These and other noncanonical ways of DNA repair that contribute to mutagenesis, survival, and evolution are reviewed in this manuscript.

The interaction of InvF-RNAP is mediated by the chaperone SicA in Salmonella sp: an in silico prediction.

In this work we carried out an in silico analysis to understand the interaction between InvF-SicA and RNAP in the bacterium Salmonella Typhimurium strain LT2. Structural analysis of InvF allowed the identification of three possible potential cavities for interaction with SicA. This interaction could occur with the structural motif known as tetratricopeptide repeat (TPR) 1 and 2 in the two cavities located in the interface of the InvF and α-CTD of RNAP. Indeed, molecular dynamics simulations showed that SicA stabilizes the Helix-turn-Helix DNA-binding motifs, i.e., maintaining their proper conformation, mainly in the DNA Binding Domain (DBD). Finally, to evaluate the role of amino acids that contribute to protein-protein affinity, an alanine scanning mutagenesis approach, indicated that R177 and R181, located in the DBD motif, caused the greatest changes in binding affinity with α-CTD, suggesting a central role in the stabilization of the complex. However, it seems that the N-terminal region also plays a key role in the protein-protein interaction, especially the amino acid R40, since we observed conformational flexibility in this region allowing it to interact with interface residues. We consider that this analysis opens the possibility to validate experimentally the amino acids involved in protein-protein interactions and explore other regulatory complexes where chaperones are involved.

8-OxoG-Dependent Regulation of Global Protein Responses Leads to Mutagenesis and Stress Survival in Bacillus subtilis.

The guanine oxidized (GO) system of Bacillus subtilis, composed of the YtkD (MutT), MutM and MutY proteins, counteracts the cytotoxic and genotoxic effects of the oxidized nucleobase 8-OxoG. Here, we report that in growing B. subtilis cells, the genetic inactivation of GO system potentiated mutagenesis (HPM), and subsequent hyperresistance, contributes to the damaging effects of hydrogen peroxide (H2O2) (HPHR). The mechanism(s) that connect the accumulation of the mutagenic lesion 8-OxoG with the ability of B. subtilis to evolve and survive the noxious effects of oxidative stress were dissected. Genetic and biochemical evidence indicated that the synthesis of KatA was exacerbated, in a PerR-independent manner, and the transcriptional coupling repair factor, Mfd, contributed to HPHR and HPM of the ΔGO strain. Moreover, these phenotypes are associated with wider pleiotropic effects, as revealed by a global proteome analysis. The inactivation of the GO system results in the upregulated production of KatA, and it reprograms the synthesis of the proteins involved in distinct types of cellular stress; this has a direct impact on (i) cysteine catabolism, (ii) the synthesis of iron-sulfur clusters, (iii) the reorganization of cell wall architecture, (iv) the activation of AhpC/AhpF-independent organic peroxide resistance, and (v) increased resistance to transcription-acting antibiotics. Therefore, to contend with the cytotoxic and genotoxic effects derived from the accumulation of 8-OxoG, B. subtilis activates the synthesis of proteins belonging to transcriptional regulons that respond to a wide, diverse range of cell stressors.

Bioactivity of Myrtus communis from the Montenegro coastline / Bioactividad de Myrtus communis del litoral de Montenegro

Although numerous studies have demonstrated the biomedical potential of Myrtus communis L., (Myrtaceae) data on myrt le from Montenegro are scarce. T o evaluate antioxidant, antimutagenic and antibacterial activity of myrtle methanolic extracts. Antioxidant activity was evaluated by measuring free radicals scavenging activity, reducing power and enzyme inhibition. The strongest scavenging activity was towards DPPH radical ( 2,2 - diphenyl - 1 - picry lhydrazyl) (IC 50 1.69 - 2.25 mg/mL) and superoxide anion (IC 50 0.56 to 0.88 mg/mL), followed by high reducing power (428 - 472 mgAA/g.DE) and inhibition of XOD (IC 50 0.308 - 0.6261mg/mL). Antimutagenic activity was evaluated in reverse mutation assays with Esche richia coli WP2 oxyR mutant IC202 and deficient in the induction of antioxidant enzymes. The myrtle extracts strongly inhibited mutagenesis induced by t - BOOH, reaching 70% at the highest concentration applied. Antimicrobial activity was examined on eight different bacterial strains. Gram - positive bacteria, S. epidermis , S. aureus and M. flavus demonstrated the highest sensitivity towards extracts (MICs 4.5 - 9 mg/mL), but significantly lower towards essential oil (MIC 0.42 - 3.32 mg/mL).

Aunque numerosos estudios han demostrado el potencial biomédico de Myrtus communis L., (Myrtaceae), los datos sobre el mirto de Montenegro son escasos. E valuar la actividad antioxidante, antimutagéni ca y antibacteriana de extractos metanólicos de mirto. La actividad antioxidante se evaluó midiendo la actividad de eliminación de radicales libres, el poder reductor y la inhibición enzimática. La actividad secuestrante más fuerte fue hacia DPPH radical ( IC 50 1.69 - 2.25 mg/mL) y radicales de anión superóxido (IC 50 0.56 a 0.88 mg/mL), seguido de alto poder reductor (428 - 472 m gAA/g.DE) e inhibición de XOD (I C 50 0,308 - 0,6261 mg/m L ). La actividad antimutagénica se evaluó en ensayos de mutación inversa con Esche richia coli WP2 oxyR mutante IC202 y deficiente en la inducción de enzimas antioxidantes. Los extractos de mirto inhibieron fuertemente la mutagénesis inducida por t - BOOH, alcanzando el 70% a la mayor concentración aplicada. La actividad antimicrobiana se examinó en octo cepas bacterianas diferentes. Las bacterias grampositivas, S. epidermis , S. aureus y M. flavus demostraron la sensibilidad más alta hacia los extractos (MIC 4.5 - 9 mg/mL), pero significativamente más baja hacia el aceite esencial (MIC 0.42 - 3 .32 mg/mL). Los resultados muestran la gran perspectiva nutrafarmacéutica de la especie montenegrina Myrtus communis .

Toxicogenetic, biochemical, and anatomical effects of the herbicide Clethodim on Allium cepa L.

Pesticides are compounds with several chemical or biological agents developed to potentiate the biocide action. Their use is associated with increased economic and agricultural productivity worldwide but can harm health and the environment, damaging existing biota. Clethodim is a systemic post-emergent herbicide for grasses, highly selective for cotton, coffee, onions, carrots, soybeans, etc. Therefore, this work aimed to evaluate the harmful effect of the herbicide Clethodim with the model plant Allium cepa. A series of tests were conducted to evaluate the effects of the herbicide under study. Germination tests, root growth, cell, and nucleolar cycle analysis, as well as oxidative stress assessment and histological analysis of the roots, were performed. The results indicated that the herbicide demonstrated phytotoxicity, inhibiting germination at C1 (1.92 g/L) and C3 (0.84 g/L), and root growth at all concentrations, presenting mutagenicity at C1 (1.92 g/L) and C4 (0.24 g/L), evidenced by the increased frequency of micronuclei. In addition, changes were observed in the enzymatic activity of the enzymes catalase at concentrations C1 (1.92 g/L) and C2 (0.96 g/L) and ascorbate peroxidase at concentrations C1 (1.92 g/L), C2 (0. 96 g/L), and C3 (0.48 g/L) and in cell elongation at concentrations C1 (1.92 g/L) and C3 (0.48 g/L), demonstrated in histological analyses of the root apex.

Red Fluorescent Protein Variant with a Dual-Peak Emission of Fluorescence.

The marine environment is a rich reservoir of diverse biological entities, many of which possess unique properties that are of immense value to biotechnological applications. One such example is the red fluorescent protein derived from the coral Discosoma sp. This protein, encoded by the DsRed gene, has been the subject of extensive research due to its potential applications in various fields. In the study, a variant of the red fluorescent protein was generated through random mutagenesis using the DsRed2 gene as a template. The process employed error-prone PCR (epPCR) to introduce random mutations, leading to the isolation of twelve gene variants. Among these, one variant stood out due to its unique spectral properties, exhibiting dual fluorescence emission at both 480 nm (green) and 550 nm (red). This novel variant was expressed in both Escherichia coli and zebrafish (Danio rerio) muscle, confirming the dual fluorescence emission in both model systems. One of the immediate applications of this novel protein variant is in ornamental aquaculture. The dual fluorescence can serve as a unique marker or trait, enhancing the aesthetic appeal of aquatic species in ornamental settings.

Chemical Composition and Evaluation of Antibacterial, Antibiofilm, and Mutagenic Potentials of a Propolis Sample from the Atlantic Forest of Midwest Brazil.

Sixteen triterpenoids with various skeletal types, five phenylpropanoid derivatives, and two flavonoids were isolated from a propolis sample produced by Apis mellifera collected in the Atlantic Forest of Midwest Brazil. Among these compounds, six triterpenes, namely 3ß,20R-dihydroxylanost-24-en-3-yl-palmitate, (23E)-25-methoxycycloartan-23-en-3-one, 24-methylenecycloartenone, epi-lupeol, epi-α-amyrin, and epi-ß-amyrin are being reported for the first time in propolis, while cycloartenone, (E)-cinnamyl benzoate, and (E)-cinnamyl cinnamate are new findings in Brazilian propolis. The presence of cycloartane- and lanostane-type triterpenoids, the latter being a class of compounds of restricted distribution in propolis worldwide, has not been reported in propolis from Midwest Brazil until now. The ethyl acetate phase obtained from the ethanol extract was effective in preventing biofilm formation by Staphylococcus aureus, with an inhibition rate of about 96 % at 0.5 mg.mL-1 , and with quercetin isolated as one of its active constituents. In contrast, the hexane phase exhibited notable antibacterial activity against Pseudomonas aeruginosa, inhibiting bacterial growth by 92 % at 0.5 mg.mL-1 ; however, none of the triterpenoids isolated from this phase proved active against this pathogen. The ethanol extract was neither toxic nor mutagenic at the concentrations tested, as determined by the in vivo SMART assay on Drosophila melanogaster, even under conditions of high metabolic activation.

Phagekines: Directed Evolution and Characterization of Functional Cytokines Displayed on Phages.

The current chapter focuses on the use of filamentous phages to display and modify biologically active cytokines, with special emphasis on directed evolution of novel variants showing improved receptor binding. Cytokines are essential protein mediators involved in cell-to-cell communication. Their functional importance and the complexity of their interactions with multichain receptors make cytokine engineering a promising tool for the discovery and optimization of therapeutic molecules. Protocols used at the laboratory are illustrated through examples of manipulation of interleukin-2 and interleukin-6, two members of the family of alpha-helix-bundle cytokines playing pivotal roles in immunity and inflammation.

Rational design of biocatalysts based on covalent immobilization of acylase enzymes.

Acylases catalyze the hydrolysis of amide bonds. Penicillin G acylase (PGA) is used for the semi-synthesis of penicillins and cephalosporins. Although protein immobilization increases enzyme stability, the design of immobilized systems is difficult and usually it is empirically performed. We describe a novel application of our strategy for the Rational Design of Immobilized Derivatives (RDID) to produce optimized acylase-based immobilized biocatalysts for enzymatic bioconversion. We studied the covalent immobilization of the porcine kidney aminoacylase-1 onto aldehyde-based supports. Predictions of the RDID1.0 software and the experimental results led to the selection of glyoxyl-Sepharose CL 4B support and pH 10.0. One of the predicted clusters of reactive amino groups generates an enzyme-support configuration with highly accessible active sites, contributing with 82% of the biocatalyst's total activity. For Escherichia coli PGA, the predictions and experimental results show similar maximal amounts of immobilized protein and activity at pH 8.0 and 10.0 on glyoxyl-Sepharose CL 10B. However, thermal stability of the immobilized derivative is higher at pH 10.0 due to an elevated probability of multipoint covalent attachment. In this case, two clusters of amino groups are predicted to be relevant for PGA immobilization in catalytically competent configurations at pH 10.0, showing accessible active sites and contributing with 36% and 44% of the total activity, respectively. Our results support the usefulness of the RDID strategy to model different protein engineering approaches (site-directed mutagenesis or obtainment of fusion proteins) and select the most promising ones, saving time and laboratory work, since the in silico-designed modified proteins could have higher probabilities of success on bioconversion processes.

Absence of maternal-fetal adverse effects of Alternanthera littoralis P. Beauv. following treatment during pregnancy in mice.

Alternanthera littoralis P. Beauv is a plant native to Brazil that exhibits various beneficial activities including antioxidant, antibacterial, antifungal, antiprotozoal, anti-hyperalgesic, and anti-inflammatory properties. The aim of this study was to assess the impact of the ethanol extract of Alternanthera littoralis (EEAl) on reproductive outcomes, embryofetal development, and DNA integrity of pregnant female mice. Pregnant Swiss female mice were randomly assigned to three experimental groups (n = 10): controls were administered either 1% Tween 80 (vehicle), EEAl 100 mg/kg or EEAl 1000 mg/kg. Treatment was administered through gavage during the gestational period until day 18. On gestational days 16, 17, and 18, a peripheral blood sample from the tail vein was obtained for DNA integrity analysis (micronucleus test). After the last collection, animals were euthanized by cervical dislocation. Maternal organs and fetuses were collected, weighed, and subsequently analyzed. Reproductive outcome parameters were assessed by measurement of number of implants, live fetuses, and resorptions. Embryonic development was determined by adequacy of weight for gestational age as well as determination of external, visceral, and skeletal malformations. Data demonstrated that EEAl did not produce maternal toxicity at either dose associated with no marked alterations in any of the reproductive outcome parameters including implantation sites, live/dead fetuses ratio, fetal viability, post-implantation losses, resorptions, and resorption rate. However, EEAl 1000 group reduced embryofetal development by lowering placental weight. In addition, there was an increase in the frequency of external and skeletal malformations in the EEAl 1000 group, which could not be attributed to extract exposure as these values were within control levels. Based upon our findings, evidence indicates that the EEAl at the concentrations employed in our study may be considered safe for use during pregnancy and extracts of this plant show potential for development of phytomedicines to be used in pregnancy.

Toxicological safety, antioxidant activity and phytochemical characterization of leaf and bark aqueous extracts of Commiphora leptophloeos (Mart.) J.B. Gillett.

This study aimed to characterize the phytochemical profile of bark and leaves aqueous extract Commiphora leptophloeos, and conduct in vivo and in vitro assays to determine the presence of any toxicological consequences due to exposure. The phytochemical analysis was carried out using high-performance liquid chromatography (HPLC). The antioxidant activity was estimated utilizing DPPH free radical scavenging and phosphomolybdenum assays. Cell viability was measured by the MTT method on J774 and human adenocarcinoma cells, which were treated with concentrations of 12,5, 25, 50, 100 or 200 µg/ml of both extracts. Acute oral toxicity, genotoxicity, and mutagenicity assays were determined using a single oral dose of 2000 g/kg in male Swiss albino mice (Mus musculus). Biochemical analysis of the blood and histological analyses of the kidneys, liver, spleen, pylorus, duodenum and jejunum were undertaken. Genotoxicity and mutagenicity were determined utilizing blood samples. Gallic acid, catechin, and epicatechin were identified in the bark and chlorogenic acid in leaves. Data demonstrated a high content of phenolic compounds and flavonoids associated with significant antioxidant potential. No significant signs in damage or symptoms of toxicity were detected. No marked reduction in cell viability was found at lower concentrations tested. On histomorphometry, only the gastrointestinal organs exhibited significant difference. Renal hepatic and blood parameters were within the normal range. No apparent signs of toxicity, genotoxicity, mutagenicity or cytotoxicity were found in vivo and in vitro experiments.

Relevance of aromatic and polar amino acids in the specificity of Inulinase ISO3 from Kluyveromyces marxianus: A molecular dynamics approach with an experimental verification.

The Inulinase from Kluyveromyces marxianus ISO3 (Inu-ISO3) is an enzyme able to hydrolyze linear fructans such as chicory inulin as well as branched fructans like agavin. This enzyme was cloned and expressed in Komagataella pastoris to study the role of selected aromatic and polar residues in the catalytic pocket by Alanine scanning. Molecular dynamics (MD) simulations and enzyme kinetics analysis were performed to study the functional consequences of these amino acid substitutions. Site-directed mutagenesis was used to construct the mutants of the enzyme after carrying out the MD simulations between Inu-ISO3 and its substrates. Mutation Trp79:Ala resulted in the total loss of activity when fructans were used as substrates, while with sucrose, the activity decreased by 98 %. In contrast, the mutations Phe113:Ala and Gln236:Ala increased the invertase activity when sucrose was used as a substrate. Although these amino acids are not part of the conserved motifs where the catalytic triad is located, they are essential for the enzyme's activity. In silico and experimental approaches corroborate the relevance of these residues for substrate binding and their influence on enzymatic activity.

Toxic Determination of Cry11 Mutated Proteins Obtained Using Rational Design and Its Computational Analysis.

Cry11 proteins are toxic to Aedes aegypti, the vector of dengue, chikungunya, and Zika viruses. Cry11Aa and Cry11Bb are protoxins, which when activated present their active-toxin form in two fragments between 30 and 35 kDa respectively. Previous studies conducted with Cry11Aa and Cry11Bb genes using DNA shuffling generated variant 8, which presented a deletion in the first 73 amino acids and one at position 572 and 9 substitutions including L553F and L556W. In this study, variant 8 mutants were constructed using site-directed mutagenesis, resulting in conversion of phenylalanine (F) and tryptophan (W) to leucine (L) at positions 553 and 556, respectively, producing the mutants 8F553L, 8W556L, and 8F553L/8W556L. Additionally, two mutants, A92D and C157R, derived from Cry11Bb were also generated. The proteins were expressed in the non-crystal strain BMB171 of Bacillus thuringiensis and subjected to median-lethal concentration (LC50) tests on first-instar larvae of A. aegypti. LC50 analysis showed that the 8F553L, 8W556L, 8F553L/8W556L, and C157R variants lost their toxic activity (>500 ng·mL-1), whereas the A92D protein presented a loss of toxicity of 11.4 times that of Cry11Bb. Cytotoxicity assays performed using variant 8, 8W556L and the controls Cry11Aa, Cry11Bb, and Cry-negative BMB171 on the colorectal cancer cell line SW480 reported 30-50% of cellular viability except for BMB171. Molecular dynamic simulations performed to identify whether the mutations at positions 553 and 556 were related to the stability and rigidity of the functional tertiary structure (domain III) of the Cry11Aa protein and variant 8 showed the importance of these mutations in specific regions for the toxic activity of Cry11 against A. aegypti. This generates pertinent knowledge for the design of Cry11 proteins and their biotechnological applications in vector-borne disease control and cancer cell lines.

Chemical characterization of Brazilian savannah Byrsonima species (muricis) and their impact on genomic instability and chemopreventive effects.

The identification of new drugs with few or no adverse effects is of great interest worldwide. In cancer therapy, natural products have been used as chemopreventive and chemotherapeutic agents. Plants from the Brazilian savannah belonging to the Byrsonima genus are popularly known as muricis and have attracted much attention due to their various pharmacological activities. However, there are currently no data on these plants concerning their use as chemopreventive or chemotherapeutic agents in human cell lines. The present study assessed the potential of B. correifolia, B. verbascifolia, B. crassifolia, and B. intermedia extracts as natural alternatives in the prevention and/or treatment of cancer. The chemical constituents present in each extract were analyzed by electrospray ionization-mass spectrometry (ESI-MSN). The mutagenic/antimutagenic (micronucleus assay), genotoxic/antigenotoxic (comet assay), apoptotic/necrotic (acridine orange/ethidium bromide uptake), and oxidative/antioxidative (CM-H2DCFDA) effects of the extracts and their influence on gene expression (RTqPCR) were investigated in nonmetabolizing gastric (MNP01) and metabolizing hepatocarcinoma (HepG2) epithelial cells to evaluate the effects of metabolism on the biological activities of the extracts. The genotoxicity, mutagenicity, and apoptotic effects observed in HepG2 cells with B. correifolia and B. verbascifolia extracts are probably associated with the presence of proanthocyanidins and amentoflavone. In MNP01 cells, none of the four extracts showed mutagenic effects. B. crassifolia and B. intermedia extracts exhibited strong antimutagenicity and enhanced detoxification in HepG2 cells and antioxidant capacities in both types of cells, possibly due to the presence of gallic and quinic acids, which possess chemopreventive properties. This study identifies for the first time B. correifolia and B. verbascifolia extracts as potential agents against hepatocarcinoma and B. crassifolia and B. intermedia extracts as putative chemopreventive agents.