Since the discovery of the o2 mutation in maize, many studies have reported the characterization of the protein quality of opaque‐2 genotypes. However, few have reported the properties of their starch. The objective of this study was to characterize flour starch properties of 12 half‐sib families of opaque‐2 maize from Argentina. Chemical composition and thermal and pasting properties of whole grain flour were determined. Nonopaque genotypes were used as a control. Starch content of opaque‐2 genotypes did not show significant differences compared with nonopaque genotypes, yet amylose content was significantly lower. A high variability in pasting and thermal properties was observed in genotypes. Opaque samples showed a significantly higher peak viscosity and a lower pasting temperature compared with nonopaque samples, probably owing to larger and less compact starch granules in the floury endosperm. The higher the gelatinization enthalpy of opaque‐2 genotypes was, the lower the amylose content in relation to nonopaque varieties. Two retrogradation endotherms were observed in DSC analysis: one corresponding to amylopectin crystallization and the other to melting of amylose‐lipid complex. Both enthalpies were considered total starch retrogradation (ΔHRT). A wide range of variation was obtained in ΔHRT in opaque‐2 genotypes, but no significant differences between opaque and nonopaque genotypes were observed. The differences in starch properties found in this study would make it possible to identify opaque‐2 families with particular characteristics for the development of starchy food items adapted to specific processing traits.

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. Provided institutional support for the research development. ABSTRACT Purpose:To evaluate the histopathology alterations of the intestinal mucosa of rabbits submitted to mesenteric artery ischemia and reperfusion with and without ischemic preconditioning. Methods: Two groups of ten male New Zealand white rabbits body (weight 2.2-3.0, average 2.5 kg). For mesenteric ischemia induction in all animals the small bowel and mesentery were cut 30cm and 60cm far from the gastroduodenal pyloric transition before the proximal mesenteric artery occlusion. In the Group 1 animals, the proximal mesenteric artery was occluded for 45 min with an atraumatic vascular clamp, followed by reperfusion for 30 min. In the Group 2 the 45 min ischemic phase was preceded by three cycles of ischemia (2 minutes each) alternated with three cycles of reperfusion (2 minutes each). For istopathology study small bowel biopsies were obtained before ischemia (control), after 45 min of mesenteric ischemia and at 30 min. of mesenteric artery reperfusion. Results: In the Group I animals, the followings histopathology grade results were observed: t1, mean 2,8; t2, mean 3,3. Using the Kruskal-Wallis non-parameter test, differences between t0 and t1 and t0 and t2 were significants (p<0.05), but not significant between t1 and t2 (p>0.05). In the Group 2 animals histopathology grade results were: t1 mean 2,6 and t2, mean 2,1. Differences between t0 and t1, t0 and t2 were significant (p<0.05). It was not observed differences (p>0.05) between results of t1 in both groups but histopathology injury observed in Group 1 t2 biopsies were higher (p<0.05) than observed in the same period (t2) of Group 2 animals. Conclusion: Microscopic examination of the biopsies revealed significant evidence of preconditioning protection against small bowel wall ischemia-reperfusion injury. Key words: Mesenteric Vascular Occlusion. Ischemic Preconditioning. Animal Experimentation. Rabbits. RESUMOObjetivo: Avaliar as alterações histopatológicas da mucosa intestinal de coelhos submetidos a isquemia-reperfusão com e sem precondicionamento isquêmicol. Métodos: Foram estudados dois grupos de dez coelhos Nova Zelândia machos com pesos variáveis entre 2,2 e 3,0 kg (média de 2,5 kg) de peso corpóreo. Para indução da isquemia, em todos os animais, o intestino delgado e o mesentério foram seccionados 30 cm e 60 cm após a transição pilórica gastroduodenal, antes da oclusão da artéria mesentérica cranial. Nos animais do Grupo 1, a artéria mesentérica proximal foi ocluida por pinçamento atraumático durante 45 min., seguido de reperfusão por 30 min. No Grupo 2, foi realizado precondicionamento por três ciclos de 2 min. de oclusão mesentérica intercalados com três ciclos de 2 min. de reperfusão, seguido de oclusão mantida por 45 min e reperfusão de 30min. como no Grupo I. Para estudo histopatológico, foram obtidas biópsias da parede intestinal antes da isquemia (t 0 -controle), após 45 min. de isquemia (t 1 ) e após 30 min. de reperfusão (t 2) . Resultados: No Grupo I foram observados os segu...

<p class="western" style="margin-bottom: 0cm; line-height: 150%;" align="justify"><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">El objetivo fue caracterizar y comparar la composición proteica de familias de medios hermanos de maíz </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>opaco-2</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> de Argentina mediante prueba de progenie. Se determinó dureza del grano, contenido de fracciones proteicas, aminoácidos y digestibilidad </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>in vitro</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> de proteína (PD) de la harina integral. Se usaron genotipos no-opacos como control. El contenido total de proteína de los genotipos </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>o2</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> correlacionó negativamente con la dureza del grano (</span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>r</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">=-42 en 2012 y </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>r</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">=-0.32 en 2013) y no mostró diferencias significativas respecto a los genotipos no-opacos; sin embargo, los genotipos </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>o2</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> mostraron mayor PD, menor proporción de zeína y mayor de albúminas, globulinas y glutelinas. Las progenies </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>o2</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> mostraron mayor contenido de lisina, isoleucina y treonina en comparación con el maíz blanco. El contenido de lisina, el de fracciones proteicas y la PD mostraron una mayor contribución de la varianza genética, a pesar de la alta contribución de la varianza del año observada en el contenido total de proteínas. </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;">Las diferencias mostradas por los perfiles de proteínas de las progenies permitirán identificar genotipos </span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"><em>o2</em></span></span></span><span style="color: #222222;"><span style="font-family: Times New Roman, serif;"><span style="font-size: medium;"> con menor nivel de zeína y mayor contenido de lisina. Esto permitirá continuar con la selección y la mejora genética para obtener variedades con calidad proteica superior. </span></span></span></p>