GEMS-0067 (PI 643420) maize line is a homozygous mutant of the recessive amylose-extender (ae) allele and an unknown number of high-amylose modifier (HAM) gene(s). GEMS-0067 produces starch with a approximately 25% higher resistant-starch (RS) content than maize ae single-mutant starches. The objective of this study was to understand how the HAM gene(s) affected the RS content and other properties of ae-background starches. Nine maize samples, including G/G, G/F1, G/H, F1/G, F1/F1, F1/H, H/G, H/F1, and H/H with HAM gene-dosages of 100, 83.3, 66.7, 66.7, 50, 33.3, 33.3, 16.7, and 0%, respectively, were produced from self- and intercrosses of GEMS-0067 (G), H99ae (H), and GEMS-0067xH99ae (F1) in a generation-means analysis (GMA) study. RS contents of examined starches were 35.0, 29.5, 28.1, 32.0, 28.2, 29.4, 12.9, 18.4, and 15.7%, respectively, which were significantly correlated with HAM gene-dosage (r = 0.81, p < 0.01). Amylose content, number of elongated starch granules, and conclusion gelatinization temperature increased with the increase in HAM gene-dosage. X-ray diffraction study showed that the relative crystallinity (%) of starch granules decreased with the increase in HAM gene-dosage. The results suggested that the HAM gene-dosage was responsible for changes in starch molecular structure and organization of starch granules and, in turn, the RS formation in the maize ae mutant starch.

Abstract:Quantitative autoradiography was used to compare the binding properties of a7-type nicotinic acetylcholine receptors in fetal and adult rat hippocampus. Whereas there were high levels of 125l-a-bungarotoxin (1251-a-BTX) binding throughout fetal hippocampal field CAl, there was a significant decrease in binding site density in the adult. The affinity of 1251-a-BTX binding, as well as a-cobratoxin and nicotine potency to displace 1251-a-BTX, did not change with age. Addition of Ca2~to the assay buffer did not alter 1251-a-BTX binding, or a-cobratoxin inhibition of 125l-ct-BT)( binding, although it significantly increased nicotine affinity at both ages. The effect of Ca2õn agonist affinity was dose-dependent, with an EC 50 value of 0.25-0.5 mM. Ca 2~also significantly increased the cooperativity of nicotine displacement curves in stratum oriens of the adult, but not in the fetus. These findings indicate that the properties of hippocampal 1251-a-BTX binding sites are largely similar across age. Ca2~selectively enhances the affinity of agonist binding, with no change in antagonist binding. This ionic effect may result from potentiation of agonist binding to a desensitized state of the a7 nicotinic acetylcholine receptor and may represent an important neuroprotective mechanism. Key Words: Autoradiography-a-BungarotoxinDevelopment-Nicotine.

ResumenEl trabajo que se presenta a continuación fue desarrollado durante la clase de investigación en el aula, en el transcurso de ésta, encontramos que aun nosotros como estudiantes universitarios, tenemos problemas al operar entre fracciones, y es por este motivo, que buscamos proponer un método de enseñanza de las mismas, para facilitar el proceso de aprendizaje de los niños con respecto a este tema, aplicando una prueba diagnostico a estudiantes de grado 4, y evidenciando las falencias, que poseen ellos.Palabras-clave: Matemáticas escolares; números; estructuras numéricas; números racionales; fracción parte-todo; operaciones básicas; otras nociones de Educación Matemática; sistemas de representación gráfica; contexto continuo; contexto discreto. AbstractThe work presented here was developed for the kind of research in the classroom, in the course of this, we find that even we as college students, we have problems to operate between fractions, and for this reason, that we propose a teaching method thereof, to facilitate the learning process of children with regard to this issue, applying a diagnostic test students in grade 4, and showing the flaws that have them.