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Patricia Tamez-Guerra

Bio: Patricia Tamez-Guerra is an academic researcher from Universidad Autónoma de Nuevo León. The author has contributed to research in topics: Medicine & Bacillus thuringiensis. The author has an hindex of 21, co-authored 105 publications receiving 1252 citations. Previous affiliations of Patricia Tamez-Guerra include National Center for Agricultural Utilization Research & United States Department of Agriculture.


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Journal ArticleDOI
TL;DR: The great endophytes diversity, their metabolites production, and their adaptation to stress conditions make them a suitable and unlimited source of novel metabolites, whose application could reduce agrochemicals usage in food and drugs production.
Abstract: Endophytes constitute plant-colonizing microorganisms in a mutualistic symbiosis relationship. They are found in most ecosystems reducing plant crops' biotic and abiotic stressors by stimulating immune responses, excluding plant pathogens by niche competition, and participating in antioxidant activities and phenylpropanoid metabolism, whose activation produces plant defense, structural support, and survival molecules. In fact, metabolomic studies have demonstrated that endophyte genes associated to specific metabolites are involved in plant growth promotion (PGP) by stimulating plant hormones production such as auxins and gibberellins or as plant protective agents against microbial pathogens, cancer, and insect pests, but eco-friendly and eco-safe. A number of metabolites of Gram-positive endophytes isolated from agriculture, forest, mangrove, and medicinal plants, mainly related to the Firmicutes phyla, possess distinctive biocontrol and plant growth-promoting activities. In general, Actinobacteria and Bacillus endophytes produce aromatic compounds, lipopeptides, plant hormones, polysaccharides, and several enzymes linked to phenylpropanoid metabolism, thus representing high potential for PGP and crop management strategies. Furthermore, Actinobacteria have been shown to produce metabolites with antimicrobial and antitumor activities, useful in agriculture, medicine, and veterinary areas. The great endophytes diversity, their metabolites production, and their adaptation to stress conditions make them a suitable and unlimited source of novel metabolites, whose application could reduce agrochemicals usage in food and drugs production.

116 citations

Journal ArticleDOI
TL;DR: Stability of B. thuringiensis stability, after simulated sunlight and rain and rain, was improved using formulations based on lignin, corn flours, or both, with up to 20% of the active ingredient, when compared with technical powder or Dipel 2× in laboratory assays.
Abstract: Bacillus thuringiensis Berliner is a highly efficacious bioinsecticide used to control lepidopteran pests in the field. Unfortunately, it has limited residual activity on plants because sunlight inactivates spores and crystals and they can be washed off by rain. To minimize loss of activity, formulations must contain UV protectants, stickers, or both. We tested approximately 80 formulations and determined optimal combinations of ingredients and spray drying conditions for improving B. thuringiensis residual activity after simulated rain and simulated sunlight. B. thuringiensis stability, after simulated sunlight (xenon light/8 h) and rain (5 cm/50 min), was improved using formulations based on lignin, corn flours, or both, with up to 20% of the active ingredient, when compared with technical powder or Dipel 2x in laboratory assays. Two formulations, made with corn flours or lignin + pregelatinized corn flour (PCF), killed 51.6 and 75.3% of Ostrinia nubilalis (Hubner) neonates after rain, respectively, versus 27% for technical powder. When the insecticidal activity was tested after simulated sunlight, corn flour-based formulations killed 78.5% of test larvae, and the lignin + PCF formulation killed 70.4%, in contrast to technical powder which caused an average of 29% mortality. Formulations made with Dipel 2x rather than technical powder, caused 62.5% mortality (corn flour-based formulations), and 72.3% mortality (lignin + PCF), versus 53.4% for Dipel 2x after rain. When tested after simulated sunlight, formulations killed 95% of the larvae (average of both formulations) versus 82% for Dipel 2x. In a field test, formulations were applied to cabbage and insecticidal activity was determined against Trichoplusia ni (Hubner) neonates exposed to treated leaves. Insecticidal activity of the corn flour-based formulations was comparable to Dipel 2x for 4 d after treatment, but was significantly better than Dipel 2x 7 d after application. A lignin and PCF-based formulation showed significantly higher residual activity than Dipel 2x, 4 and 7 d after application.

72 citations

Journal ArticleDOI
TL;DR: It is demonstrated that formulations made with natural ingredients could improve persistence of virus-based biopesticides if improved formulations can prevent rapid loss of insecticidal activity from environmental conditions such as sunlight and rainfall.
Abstract: Nuclear polyhedrosis viruses such as the one isolated from the celery looper, Anagrapha falcifera (Kirby) (AfMNPV), have the potential to be successful bioinsecticides if improved formulations can prevent rapid loss of insecticidal activity from environmental conditions such as sunlight and rainfall. We tested 16 spray-dried formulations of AfMNPV to determine the effect of different ingredients (e.g., lignin, corn flour, and so on) on insecticidal activity after simulated rain and simulated sunlight (at Peoria, IL) and natural sunlight exposures (at Tifton, GA). The most effective formulation contained pregelatinized corn flour and potassium lignate, which retained more than half of its original activity after 5 cm of simulated rain, and almost full activity after 8 h of simulated sunlight. In Georgia, formulations made with and without lignin were compared for persistence of insecticidal activity when exposed to natural sunlight. In addition, the effect of fluorescent brighteners as formulation components and spray tank additives was tested. Results showed that the formulations with lignin had more insecticidal activity remaining after sunlight exposure than formulations without lignin. The inclusion of brighteners in the formulation did not improve initial activity or virus persistence. However, a 1% tank mix significantly enhanced activity and improved persistence. Scanning electron micrographs revealed discreet particles, and transmission electron micrographs showed virus embedded within microgranules. Results demonstrated that formulations made with natural ingredients could improve persistence of virus-based biopesticides.

70 citations

Journal ArticleDOI
TL;DR: PM extracts potentiated Con A‐induced lymphoproliferation in a dose‐dependent fashion, compared with the effect of ConA alone, suggesting the regulation of immune parameters induced by plant extracts may be clinically relevant in numerous diseases including chronic viral infections, tuberculosis, AIDS and cancer.
Abstract: Plantago major (PM), also known as plantain, is a weed found in temperate zones worldwide. PM leaves have been associated with various biological properties ranging from antiinflammatory, antimicrobial and antitumour to wound healing. However, its mechanism of action associated with boosting of the immune function remains to be elucidated. We found that endotoxin-free methanol extracts from PM leaves, at doses of 50, 100, 250, and 500 microg/mL, were associated with 4.4 +/- 1, 6 +/- 1, 12 +/- 0.4, and 18 +/- 0.4-fold increases of nitric oxide (NO) production, and increased TNF-alpha production (621 +/- 31, 721 +/- 36, 727 +/- 36, and 1056 +/- 52 U/mL, respectively) by rat peritoneal macrophages, in the absence of IFN-gamma or LPS. NO and TNF-alpha production by untreated macrophages was negligible. In addition, PM extracts potentiated Con A-induced lymphoproliferation (3- to 12-fold increases) in a dose-dependent fashion, compared with the effect of Con A alone. The regulation of immune parameters induced by plant extracts may be clinically relevant in numerous diseases including chronic viral infections, tuberculosis, AIDS and cancer.

66 citations

Journal ArticleDOI
TL;DR: In this article, the rotavirus pathogenesis and immunity was discussed, and probiotics such as Lactobacillus and Bifidobacterium species in combination with prebiotics have been associated with the prevention or modulation of rotivirus severe gastroenteritis.
Abstract: Annual mortality rates due to infectious diarrhea are about 2.2 million; children are the most vulnerable age group to severe gastroenteritis, representing group A rotaviruses as the main cause of disease. One of the main factors of rotavirus pathogenesis is the NSP4 protein, which has been characterized as a viral toxin involved in triggering several cellular responses leading to diarrhea. Furthermore, the rotavirus protein NSP1 has been associated with interferon production inhibition by inducing the degradation of interferon regulatory factors IRF3, IRF5, and IRF7. On the other hand, probiotics such as Bifidobacterium and Lactobacillus species in combination with prebiotics such as inulin, HMO, scGOS, lcFOS have been associated with improved generalized antiviral response and anti-rotavirus effect by the reduction of rotavirus infectivity and viral shedding, decreased expression of NSP4 and increased levels of specific anti-rotavirus IgAs. Moreover, these probiotics and prebiotics have been related to shorter duration and severity of rotavirus diarrhea, to the prevention of infection and reduced incidence of reinfections. In this review we will discuss in detail about the rotavirus pathogenesis and immunity, and how probiotics such as Lactobacillus and Bifidobacterium species in combination with prebiotics have been associated with the prevention or modulation of rotavirus severe gastroenteritis.

51 citations


Cited by
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TL;DR: Current information on development, use and future directions of insect-specific viruses, bacteria, fungi and nematodes as components of integrated pest management strategies for control of arthropod pests of crops, forests, urban habitats, and insects of medical and veterinary importance is presented.

926 citations

Journal ArticleDOI
TL;DR: Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance, and strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription is needed, hence fostering antibiotic stewardship.
Abstract: Due to the increased demand of animal protein in developing countries, intensive farming is instigated, which results in antibiotic residues in animal-derived products, and eventually, antibiotic resistance. Antibiotic resistance is of great public health concern because the antibiotic-resistant bacteria associated with the animals may be pathogenic to humans, easily transmitted to humans via food chains, and widely disseminated in the environment via animal wastes. These may cause complicated, untreatable, and prolonged infections in humans, leading to higher healthcare cost and sometimes death. In the said countries, antibiotic resistance is so complex and difficult, due to irrational use of antibiotics both in the clinical and agriculture settings, low socioeconomic status, poor sanitation and hygienic status, as well as that zoonotic bacterial pathogens are not regularly cultured, and their resistance to commonly used antibiotics are scarcely investigated (poor surveillance systems). The challenges that follow are of local, national, regional, and international dimensions, as there are no geographic boundaries to impede the spread of antibiotic resistance. In addition, the information assembled in this study through a thorough review of published findings, emphasized the presence of antibiotics in animal-derived products and the phenomenon of multidrug resistance in environmental samples. This therefore calls for strengthening of regulations that direct antibiotic manufacture, distribution, dispensing, and prescription, hence fostering antibiotic stewardship. Joint collaboration across the world with international bodies is needed to assist the developing countries to implement good surveillance of antibiotic use and antibiotic resistance.

670 citations

01 Jan 2016
TL;DR: People have search hundreds of times for their favorite books like this evolution in changing environments some theoretical explorations, but end up in malicious downloads instead of enjoying a good book with a cup of tea in the afternoon.
Abstract: Thank you very much for reading evolution in changing environments some theoretical explorations. As you may know, people have search hundreds times for their favorite books like this evolution in changing environments some theoretical explorations, but end up in malicious downloads. Rather than enjoying a good book with a cup of tea in the afternoon, instead they juggled with some harmful bugs inside their laptop.

621 citations

Journal ArticleDOI
TL;DR: Modeling results show that fitness costs can delay resistance by selecting against Bt-resistant genotypes in refuges where insects are not exposed to Bt toxins, andRefuges designed to increase the dominance or magnitude of fitness costs could be especially useful for delaying pest resistance.
Abstract: Evolution of resistance by insect pests threatens the continued effectiveness of Bacillus thuringiensis (Bt) toxins in sprays and transgenic crops. Fitness costs of Bt resistance occur when, in the absence of Bt toxins, fitness is lower for resistant insects than for susceptible insects. Modeling results show that fitness costs can delay resistance by selecting against Bt-resistant genotypes in refuges where insects are not exposed to Bt toxins. In 77 studies including 18 species, fitness costs were detected in 62% of experiments testing for declines in resistance and in 34% of fitness component comparisons. Mean fitness costs were 15.5% for survival, 7.4% for development time, and 2.5% for mass. Although most fitness costs were recessive, nonrecessive costs can select more strongly against resistance. Because fitness costs vary with ecological conditions, refuges designed to increase the dominance or magnitude of fitness costs could be especially useful for delaying pest resistance.

459 citations