Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Evaluation of the contribution of maize germ peroxidases to resistance to the storage pest prostephanus truncatus(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2025-07) Cervantes Macedo, Elizabeth; García Lara, Silverio; emipsanchez; School of Engineering and Sciences; Campus Monterrey; González Rodríguez, América TzitzikiMaize is a globally important crop used for food, feed, and bioethanol production. However, during storage, it faces serious threats from biotic factors, such as insect pests, particularly Prostephanus truncatus, which can cause severe grain damage and losses of up to 80%, depending on the region and conditions. These infestations also affect grain quality, nutritional value, and marketability. Maize kernels exhibit various resistance mechanisms involving structural, genetic, and biochemical traits, including proteins like peroxidases. Recent studies have linked peroxidase activity to insect resistance, with activity detected in kernel tissues, including the aleurone layer, pedicel, and germ. Although peroxidase activity is mainly concentrated in the germ, little is known about the specific peroxidases involved and their role during insect interactions, creating a gap in our understanding of this defense mechanism. This research aims to analyze the role of germ peroxidases in resistance to P. truncatus in mature maize kernels and germs. Susceptibility of maize kernels and germ tissues to P. truncatus was evaluated and compared with soluble protein concentration and peroxidase activity in the germ. Additionally, a proteomic approach was employed to identify candidate peroxidases and other proteins potentially involved in resistance mechanisms. Results revealed a significant negative correlation between susceptibility traits in maize kernels and peroxidase activity in the germ, as well as a similar correlation between these traits and soluble protein concentration. These findings suggest that peroxidase activity and soluble protein accumulation in the germ likely play an important role in kernel resistance. Despite previous reports of some genotypes exhibiting low germ damage after insect interaction, all germ samples in this study showed relatively high levels of damage, regardless of genotype. Therefore, germ tissue does not exhibit any antixenosis effect. Further research is recommended to evaluate protein candidates in the germ and kernel contributing to resistance during storage.
- Tocopherol contribution to the resistance against storage pest Prostephanus truncatus in maize(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2024-12-02) Aguirre Espinoza, Carlos; García Lara, Silverio; emimmayorquin; Mora Vásquez, Soledad; School of Engineering and Sciences; Campus Monterrey; Gonzalez Rodriguez, America TzitzikiProstephanus truncatus infestation can cause losses as high as 80% on stored maize. Sources of resistance against this pest are related to the antioxidant capacity of the pericarp and aleurone layer structures, mainly due to phenolic acids content and their derivatives. Nonetheless, there is not enough information about the germ structure or the liposoluble antioxidants, such as tocopherols. To determine the contribution of tocopherols and liposoluble antioxidant capacity to the resistance against P. truncatus, thirteen genotypes of maize were tested in two confined bioassays (n=3). The first was to assess the susceptibility of each genotype. The second was with the enriched structure of the germ to gather information on damage and development of P. truncatus on this structure. Seven susceptibility parameters were recorded 7 and 60 days after infestation, and ten genotypes were selected based on a Susceptibility Selection Index, with five recognized as resistant and five as susceptible. HPLC-FLD was used to determine the content of tocopherols (δT, γT, and αT), and an ORAC assay was performed to measure the lipophilic antioxidant capacity among the ten genotypes selected. All Population 84 genotypes exhibited less damage by P. truncatus and were categorized as resistant. Three Population 84 genotypes were selected: P84C0Y (SI = 0.17), P84C4W (SI = 0.27; highest tocopherol content, 39.58 mg/kg; high L-AC, 429.04 μmol TE/g), and P84C4Y (SI = 0.51). Two selected genotypes previously recognized as susceptible were classified as resistant: Pink Creole (SI = 0.39; high tocopherol content 39.40 mg/kg; highest L-AC, 488.30 μmol TE/g) and Don Goyo (SI = 0.55). The most susceptible genotype was Red Creole (SI = 3.56; lowest L-AC, 205.48 μmol TE/g), the remaining 4 susceptible varieties selected were Peru2 (SI = 1.23), NAYA29B (SI = 1.07), Panchito (SI = 1.00; lowest tocopherol content, 11.21 mg/kg; low L-AC, 250.4 μmol TE/g), and Pozolero (SI = 0.97). Additionally, a strong correlation (p > 0.01) demonstrated that a short-length bioassay (7 days) can be comparable to a full-length bioassay (60 days). Both can measure a genotype susceptibility to P. truncatus based on weight loss, but only a full-length bioassay can provide information on adult emergence.
- Fate of aflatoxins in dry and wet-milled fractions of aspergillus flavus contaminated corn(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2023-11) Hernández Carrizales, Lucero Abigail; Serna Saldívar, Sergio Román Othón; emipsanchez; Pérez Carrillo, Esther; Escuela de Ingeniería y Ciencias; Campus Monterrey; García Lara, SilverioMaize is vulnerable to aflatoxins (AFs) contamination from the field to grain storage. Therefore, it has become a common food safety problem in the food industry. This project investigated the distribution fate of total AFs in dry and wet milled products and coproducts obtained from Aspergillus flavus contaminated maize and the concomitant effects on chemical and functional properties of derived products. White commercial maize was inoculated with A. flavus to produce AFs and then it was processed through milling protocols at laboratory scale. Quantification of AFs was determined by immunoassay and chemical properties (moisture, crude protein, crude fat, minerals) of dry and wet-milled products were determined using standard methods. Results of the dry milling process showed differences in contamination among products being hominy feed the fraction with the highest AFs content (1127.63 ppb per production yield). The main product of this milling process, brewing grits (grits +60), contained approximately 1.05% of the AF present in the whole grain. Protein content increased in grits +35, corn meal and corn flour, whereas the crude fat increased only in grits +20. Wet milling reduced 98% of the total AFs in prime starch. The starch was not significantly affected in terms of pasting properties and macronutrients when compared to the control or uncontaminated maize counterpart. The fiber fractions concentrated the AFs and had lower values of protein. In summary, the dry milling process obtained fractions differing in Afs. Fortunately, the refined brewing grits contained the lowest amounts and contamination did not significantly affected chemical properties. On the other hand, the wet milling process reduce the AFs in the prime starch, but not in fiber fractions. The overall conclusion is that both milling procedures benefited the AFs in the main products, refined grits and prime starch.
- Characterization of arbuscular mycorrhizal fungi and endophytic bacteria in mycorrhizal and non-mycorrhizal mutant maize by a metagenomics approach(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021-12-15) Guerrero Peña, Naomi Jocelyn; PACHECO MOSCOA, ADRIANA; 274621; Pacheco Moscoa, Adriana; emipsanchez; Gradilla Hernández, Misael Sebastián; Díaz de la Garza, Rocío Isabel; Escuela de Ingeniería y Ciencias; Campus Monterrey; Senés Guerrero, CarolinaArbuscular mycorrhizal fungi (AMF) establish mutualistic symbiosis with almost 80% of all plants. AMF are widely used in agriculture because they offer a substitute to chemical biofertilizers as they can boost plant growth under non-ideal conditions. Maize is the most important commercial and cultural crop in Mexico. The common symbiosis pathway (CSP) is a well conserved molecular signaling pathway in all plants that can achieve mycorrhizal and rhizobia symbiosis, which starts with specific receptors that recognize each microorganism. Here, maize-associated AMF species and endophytic bacteria composition from two variants of maize, a mycorrhizal wild type and a non-mycorrhizal mutant type, were assessed by using high-throughput MiSeq-Illumina sequencing. Mutant maize did not possess the HUN gen, a CASTOR homologous gene, that is involved in the CSP by starting upstream Ca2+ oscillations and activating molecular signaling cascade. Composite root samples of wild type (n=9) and mutant maize (n=10) were used for microbial characterization. Mycorrhization was observed in all samples. A total of 22 AMF species were found with abundance >1%, and only 7 species were shared by both types of maize. Differences among AMF composition were observed, where mutant plants showed absence of the AMF generalist species Rhizophagus. Shannon and Chao1 diversity indexes were higher in mutant plants than wild type maize. Regarding endophytic bacteria, 137 and 135 amplicon sequence variants (AVS) were found in wild type and mutant maize, where 105 were shared by both treatments. Streptomyces and Bulkholderia were the most predominant among all samples. Streptomyces abundance suggest that this genus may play a main role in bacterial and AMF composition, as it is known for improving AMF germination and symbiosis due to its chitinase production. As mutation of HUN gene was not sufficient to block complete symbiosis between AMF and the plant, further characterization of downstream genes of the CSP in maize and field experimentation are required.
- Effect of germination with selenium in physical and chemical properties of nixtamalized maize (Zea mays L.) tortillas(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2021-06) Dávila Vega, Juan Pablo; Serna Saldivar, Sergio Román Othón; 3598; Serna Saldívar, Sergio Román Othón; tolmquevedo, emipsanchez; Antunes Ricardo, Marilena; Escuela de Ingeniería y Ciencias; Campus Monterrey; Guardado Félix, DanielaMaize is one of the most consumed cereals worldwide, especially in Mexico where staple foods like tortillas play a crucial role in the daily caloric intake, meaning in some cases up to the 40% of total caloric consumption. It has been demonstrated that germination of kernels offer an alternative for the improvement of the bioavailability of key nutrients and the intake of novel compounds like selenium (Se). Se plays a crucial role in human physiology by taking part in the antioxidant enzymatic mechanism, which is highly related to the prevention of diseases like cancer. Cancer, a multifactorial disease is generally treated with chemotherapy, although this induces negative responses and side effects in the organisms. By that, the search for preventive nutraceutical foods or complementary diets have gained attention in the last years. The main objective of the present research was to evaluate the effects of germination in the presence of Se and nixtamalization in maize tortillas in their physical, and chemical properties, and macronutrient composition. Results showed that germination can generate optimal masas and tortillas without further negative effects as chemical, physical or functional properties. This research clearly indicate the feasibility of processing sprouted grain kernels in the presence of Se via traditional nixtamalization for the production of table tortillas. The Se-enriched tortillas had excellent properties and contained high levels of Se, which is known to prevent oxidative stress and cancer
- Contribution of the maize germ (Zea mays L.) to the resistance to the postharvest pests Sitophilus zeamais and Prostephanus truncatus.(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-06-12) González Leyzaola, Alán; GARCIA LARA, SILVERIO; 123152; García Lara, Silverio; lagdtorre, emipsanchez; Winkler, Robert; Escuela de Ingeniería y Ciencias; Campus Monterrey; López Castillo, Laura MargaritaMaize (Zea Mays L.) is the most important cereal in terms of production. The maize weevil (Sitophilus zeamais) and the large grain borer (Prostephanus truncatus) are the two main postharvest insect pests that affect maize, causing losses as high as 80%. Factors attributed to resistance of maize kernels against insect pests have been widely studied in kernel structures such as pericarp, aleurone layer and endosperm. However, one structure that hasn’t been studied in this area is the germ. The aim of this study was to evaluate the contribution of the maize germ to the resistance to the attack of the postharvest insect pests S. zeamais and P. truncatus. For this purpose, we performed kernel-insect interaction assays with a duration of 60 days, testing both postharvest pests and 14 maize genotypes. For this work, we considered whole kernels and the hand-dissected germ. We recorded the main suceptibility parameters: grain weight loss, mortality rate, adult progeny and the mean development time of the pests. In order to define a group of possible metabolites which could be implicated in this resistance, we evaluated the chromatographic profiles (HPLC-DAD) of the 14 genotypes in term of phenolic compounds, in free and bound forms. We also evaluated the profile of tocopherols, phytosterols and fatty acids. Finally, we established the correlation between the susceptibility parameters determined in the insect bioassays and the evaluated compounds. Surprisingly, in the maize germ assays, although oviposition was observed after 60 days, there was no evidence of adult or larvae emergence of both pests. Furthermore, oleic acid showed a positive correlation with germ weight loss in both insect pests, while palmitic acid had a negative correlation of this parameter only in P. truncatus. Statistical differences in concentration of compounds from basal state and infested samples were detected in free and bound phenolics and liposoluble compounds. These findings provide strong evidence of an important contribution of the maize germ in the resistance against S. zeamais and P. truncatus by possible detrimental effects on early stages of development. This information could be helpful in the development of new strategies for the protection of maize kernels against S. zeamais and P. truncatus.