University of Guadalajara

About: University of Guadalajara is a education organization based out in Guadalajara, Mexico. It is known for research contribution in the topics: Population & Context (language use). The organization has 13040 authors who have published 17399 publications receiving 168085 citations. The organization is also known as: UdeG & UdG.

Genomic estimation of complex traits reveals ancient maize adaptation to temperate North America

Abstract: By 4000 years ago, people had introduced maize to the southwestern United States; full agriculture was established quickly in the lowland deserts but delayed in the temperate highlands for 2000 years. We test if the earliest upland maize was adapted for early flowering, a characteristic of modern temperate maize. We sequenced fifteen 1900-year-old maize cobs from Turkey Pen Shelter in the temperate Southwest. Indirectly validated genomic models predicted that Turkey Pen maize was marginally adapted with respect to flowering, as well as short, tillering, and segregating for yellow kernel color. Temperate adaptation drove modern population differentiation and was selected in situ from ancient standing variation. Validated prediction of polygenic traits improves our understanding of ancient phenotypes and the dynamics of environmental adaptation.

Diabetic Polyneuropathy in Type 2 Diabetes Mellitus: Inflammation, Oxidative Stress, and Mitochondrial Function.

Abstract: Diabetic polyneuropathy (DPN) is defined as peripheral nerve dysfunction. There are three main alterations involved in the pathologic changes of DPN: inflammation, oxidative stress, and mitochondrial dysfunction. Inflammation induces activation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases. Oxidative stress induced by hyperglycemia is mediated by several identified pathways: polyol, hexosamine, protein kinase C, advanced glycosylation end-products, and glycolysis. In addition, mitochondrial dysfunction accounts for most of the production of reactive oxygen and nitrosative species. These free radicals cause lipid peroxidation, protein modification, and nucleic acid damage, to finally induce axonal degeneration and segmental demyelination. The prevalence of DPN ranges from 2.4% to 78.8% worldwide, depending on the diagnostic method and the population assessed (hospital-based or outpatients). Risk factors include age, male gender, duration of diabetes, uncontrolled glycaemia, height, overweight and obesity, and insulin treatment. Several diagnostic methods have been developed, and composite scores combined with nerve conduction studies are the most reliable to identify early DPN. Treatment should be directed to improve etiologic factors besides reducing symptoms; several approaches have been evaluated to reduce neuropathic impairments and improve nerve conduction, such as oral antidiabetics, statins, and antioxidants (alpha-lipoic acid, ubiquinone, and flavonoids).

Generalized Nonquadratic Stability of Continuous-Time Takagi–Sugeno Models

Abstract: This paper provides generalized nonquadratic stability conditions for continuous-time nonlinear models in the Takagi-Sugeno (TS) form obtained by sector-nonlinearity approach. Should global quadratic stability fail for a given nonlinear model, the proposed approach allows the obtaining of progressively better estimations of the stability domain via local asymptotic conditions in the form of linear-matrix inequalities (LMIs), which are efficiently solved by convex optimization techniques. Illustrative examples are presented to emphasize the broadening capabilities of the new stability analysis.

Delayed and time-cumulative toxicity of imidacloprid in bees, ants and termites

Abstract: Imidacloprid, one of the most commonly used insecticides, is highly toxic to bees and other beneficial insects. The regulatory challenge to determine safe levels of residual pesticides can benefit from information about the time-dependent toxicity of this chemical. Using published toxicity data for imidacloprid for several insect species, we construct time-to-lethal-effect toxicity plots and fit temporal power-law scaling curves to the data. The level of toxic exposure that results in 50% mortality after time t is found to scale as t1.7 for ants, from t1.6 to t5 for honeybees, and from t1.46 to t2.9 for termites. We present a simple toxicological model that can explain t2 scaling. Extrapolating the toxicity scaling for honeybees to the lifespan of winter bees suggests that imidacloprid in honey at 0.25 μg/kg would be lethal to a large proportion of bees nearing the end of their life.

Farmers' seed selection practices and traditional maize varieties in Cuzalapa, Mexico

Abstract: Experimental results and farmer surveys from a Mexican community located in the buffer zone of a biosphere reserve indicate that farmers' seed selection practices protect the phenological integrity of their traditional maize varieties as they define them, despite numerous factors contributing to genetic instability. Analysis of morphological and genetic data suggests that when subjected to significant gene flow through cross-pollination, ear characteristics are maintained through farmers' selection even though other characteristics may continue to evolve. Because the effects of farmers' selection practices are confined largely to ear characteristics, their practices appear to offer only limited scope for variety improvement. Farmers' expectations of what they can achieve through seed selection are similarly limited. These findings suggest complementary roles for professional breeders and Mexican farmers in enhancing mass selection methods to improve maize landraces on farms – if farmers themselves perceive benefits from the collaboration.