Investigación en Matemáticas, Economía, Ciencias Sociales y Agronomía

Cada trabajo del libro incluye conclusiones para los interesados en las temáticas aludidas y en ellos nos enteramos de aspectos como los siguientes: - El mayor incremento del precio de los insumos como el maíz, sorgo y en menor medida desperdicio de pan, en relación con el menor crecimiento del precio del ganado en pie, dará como consecuencia un desabasto de carne bovina. - El agua es un recurso primordial en las zonas áridas y semiáridas de México, en tanto que su aporte limita la producción de la agricultura. En este estudio se observó que el precio real del agua es muy bajo en relación a otras zonas agrícolas del mundo. - Hoy en día en el país se consumen alrededor de 718 mil barriles diarios de gasolinas, un aproximado de 113.7 millones de litros, una cantidad tan grande que nuestro país se ve en la necesidad de importar cerca del 39 % de las gasolinas que consumimos. - Los jaliscienses radicados en Estados Unidos tienen una mayor capacidad de financiamiento del bienestar en la entidad, que el propio gobierno de ese estado. - México continuará basando sus finanzas públicas y su política de desarrollo económico en la extracción de combustibles fósiles (petróleo). Este modelo acelerará el deterioro y agotamiento de los recursos naturales. -La importancia de la agricultura orgánica radica en que retoma los tres ámbitos de la sustentabilidad; el ámbito ambiental, el económico y el social. - Es fundamental motivar la organización de los productores de haba para que ellos puedan captar una mayor proporción de los altos márgenes de precios que los consumidores están dispuestos a pagar. - Las condiciones del clima afectan a la producción agraria. Debido al fenómeno de cambio climático, es necesario contar con herramientas informáticas que proporcionen información climatológica para poder tomar medidas preventivas a favor de una mayor cantidad y calidad de producción. La herramienta de software permite la consulta del clima por localidades evitando la necesidad de contar con una estación meteorológica

Direct Stimulation of Islet Insulin Secretion by Glycolytic and Mitochondrial Metabolites in KCl-Depolarized Islets.

We have previously demonstrated that islet depolarization with 70 mM KCl opens Cx36 hemichannels and allows diffusion of small metabolites and cofactors through the β-cell plasma membrane. We have investigated in this islet "permeabilized" model whether glycolytic and citric acid cycle intermediates stimulate insulin secretion and how it correlates with ATP production (islet content plus extracellular nucleotide accumulation). Glycolytic intermediates (10 mM) stimulated insulin secretion and ATP production similarly. However, they showed differential sensitivities to respiratory chain or enzyme inhibitors. Pyruvate showed a lower secretory capacity and less ATP production than phosphoenolpyruvate, implicating an important role for glycolytic generation of ATP. ATP production by glucose-6-phosphate was not sensitive to a pyruvate kinase inhibitor that effectively suppressed the phosphoenolpyruvate-induced secretory response and islet ATP rise. Strong suppression of both insulin secretion and ATP production induced by glucose-6-phosphate was caused by 10 μM antimycin A, implicating an important role for the glycerophosphate shuttle in transferring reducing equivalents to the mitochondria. Five citric acid cycle intermediates were investigated for their secretory and ATP production capacity (succinate, fumarate, malate, isocitrate and α-ketoglutarate at 5 mM, together with ADP and/or NADP+ to feed the NADPH re-oxidation cycles). The magnitude of the secretory response was very similar among the different mitochondrial metabolites but α-ketoglutarate showed a more sustained second phase of secretion. Gabaculine (1 mM, a GABA-transaminase inhibitor) suppressed the second phase of secretion and the ATP-production stimulated by α-ketoglutarate, supporting a role for the GABA shuttle in the control of glucose-induced insulin secretion. None of the other citric acid intermediates essayed showed any suppression of both insulin secretion or ATP-production by the presence of gabaculine. We propose that endogenous GABA metabolism in the "GABA-shunt" facilitates ATP production in the citric acid cycle for an optimal insulin secretion

Reduction of plasma membrane glutamate transport potentiates insulin but not glucagon secretion in pancreatic islet cells

Glutamate is generated during nutrient stimulation of pancreatic islets and has been proposed to act both as an intra- and extra-cellular messenger molecule. We demonstrate that glutamate is not co-secreted with the hormones from intact islets or purified α- and β-cells. Fractional glutamate release was 5-50 times higher than hormone secretion. Furthermore, various hormone secretagogues did not elicit glutamate efflux. Interestingly, epinephrine even decreased glutamate release while increasing glucagon secretion. Rather than being co-secreted with hormones, we show that glutamate is mainly released via plasma membrane excitatory amino acid transporters (EAAT) by uptake reversal. Transcripts for EAAT1, 2 and 3 were present in both rat α- and β-cells. Inhibition of EAATs by L-trans-pyrrolidine-2,4-dicarboxylate augmented intra-cellular glutamate and α-ketoglutarate contents and potentiated glucose-stimulated insulin secretion from islets and purified β-cells without affecting glucagon secretion from α-cells. In conclusion, intra-cellular glutamate-derived metabolite pools are linked to glucose-stimulated insulin but not glucagon secretion

Measurement of ATP production by islets depolarized with 70 mM KCl: islet ATP content and its accumulation in the extracellular medium in response to addition of the indicated citric acid cycle intermediate and its corresponding cofactors for the pyruvate/malate or isocitrate/malate cycles. Effect of 10μM antimycin A.

<p>The experimental conditions were the same as described above in the legend of <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166111#pone.0166111.t001" target="_blank">Table 1</a>. (More information is found in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0166111#sec002" target="_blank">Materials and Methods</a> section).</p

Secretory capacity of 10 mM glucose-6-phosphate (G6P) together with 10 mM ADP and 10 mM NAD⁺ in depolarized (+KCl) islets and the effects of 10 μM rotenone (respiratory complex I inhibitor), 10 μM antimycin A (respiratory complex III inhibitor) and 10 mM phenylalanine (Phe).

<p>(A) Groups of 40 islets each, pre-perifused with 5 mM glucose (G5) for 45 min, were stimulated for 30 min (between vertical broken lines) with G5 + KCl alone (white diamonds) or together with 10 mM G6P (gray diamonds). (B) Islets were stimulated with G5 + KCl + G6P alone (white diamonds) or together with Phen (light gray diamonds), rotenone (more intense gray diamonds) or antimycin A (black diamonds). Symbols and bars represent means ± S.E.M. of 6 experiments (p<0.0001 compared with the bar to left; **p<0.03 compared with the control white bar to the left; ^#p<0.002 compared with the control white bar to the left).</p

Secretory capacity of citric acid cycle intermediates at 5 mM (succinate, SUCC; fumarate, FUM; malate, MAL; isocitrate, ISOCIT; α-ketoglutarate, α-KG), together with the needed cofactors (5 mM ADP and/or 5 mM NADP) in perifused and depolarized (+ 70 mM KCl) islets.

<p>Groups of 40 islets each, pre-perifused with 5 mM glucose (G5) for 45 min, were stimulated for 30 min (between vertical broken lines) with G5 + KCl alone (white circle) or together with each of the citric acid cycle intermediates mentioned and the required cofactors (SUC+ADP+NADP⁺; FUM+ADP; MAL+ADP+NADP⁺; α-KG+ADP+NADP⁺; ISOCIT+ADP+NADP⁺). Symbols (see the insert in the Figure) and bars represent means ± S.E.M. of 5 experiments (*p<0.01, **p<0.03, ^†p<0.03, p<0.004 and ^#p<0.002 compared with the first white bar to the left).</p

Ten mM phosphoenolpyruvate (PEP) stimulation of insulin secretion in depolarized (70 mM KCl = KCl) perifused rat islets and the effects of 10 μM rotenone (respiratory complex I inhibitor) and 15 mM phenylalanine (Phe) (pyruvate kinase inhibitor).

<p>(A) Groups of 40 islets each, pre-perifused with 5 mM glucose (G5) for 45 min, were stimulated for 30 min (between vertical broken lines) with 5 mM glucose (G5) + PEP under non-depolarizing (open symbols) or depolarizing conditions (KCl alone, gray symbols, or plus PEP, dark symbols). (B) Depolarized (G5 + KCl) islets were stimulated with PEP (+ 10 mM ADP) alone (dark diamonds) or together with rotenone (gray triangles) or rotenone + Phe (white triangles). Symbols and bars represent means ± S.E.M. of 6 experiments. (*p< 0.001 compared with the gray bar to the left; **p< 0.03 compared with the white bar to the right).</p

Measurement of ATP production by islets depolarized with 70 mM KCl: islet ATP content and its accumulation in the extracellular medium in response to addition of the indicated glycolytic intermediate and its corresponding cofactors. Effects of the complex respiratory inhibitors 10 μM rotenone and 10 μM antimycin A.

<p>Three groups, each of 25 islets, were incubated at 37°C for 60 minutes in 25 μl of KRBH. At the end of incubation, medium samples were separated and stored and islets consistently washed to dilute the contaminating extracellular nucleotide. After addition of perchloric acid to medium and islet samples, they were neutralized and potassium perchlorate precipitated. ATP was measured in samples of the clean supernatant with the luciferin/luciferase system. The emitted light was measured in a microplate reader (Synergy-2, Biotek) after addition of luciferase. More detailed information can be found in the Materials and Methods section.</p

Secretory capacity of 10 mM glyceraldhyde-3-phosphate (GAP) together with 10 mM ADP and 10 mM NAD⁺ in depolarized (+KCl) islets and the effects of 10 μM rotenone (respiratory complex I inhibitor) and 0.5 mM iodoacetate (iodoacetate).

<p>(A) Groups of 40 islets each, pre-perifused with 5 mM glucose (G5) for 45 min, were stimulated for 30 min (between vertical broken lines) with G5 + KCl alone (gray diamonds) or together with GAP (with diamonds). (B) Islets were stimulated with G5 + KCl +GAP alone (white diamonds) or together with rotenone (gray triangles) or rotenone + iodoacetate (black triangles). Symbols and bars represent means ± S.E.M. of 5 or 6 experiments (*p<0.001 compared with the gray bar to the left; ^† p< 0.05 comparing the black with the gray bar.).</p