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Antecedentes. Los organismos vivos responden al estrés aumentando la síntesis de proteínas. El estrés por choque térmico ha sido el más estudiado y las proteínas que se inducen, se han denominado genéricamente como proteínas de choque térmico. Objetivo.En este trabajo se establecieron las condiciones óptimas de producción de la proteína HSC70, expresada en E.coli BL21 (DE3) y de los anticuerpos policlonales que permitan identificarla. Material y métodos. Mediante varios ensayos se establecieron las concentraciones óptimas del agente inductor isopropil- -D-thiogalacto­piranosido (PTG), del inóculo bacteriano, de empleo de los plásmidos de expresión pET-3a y pET-28a (+); y el método más eficiente para la recuperación de las formas soluble o insoluble de la proteína y de anticuerpos policlonales que la identifiquen. Resultados. Encontramos que el inóculo de cinco colonias con IPTG (2mM) en tubos con cinco mililitros de medio modificado e incubadas por 24 horas a 37°C con agitación constante (200 r.p.m) y tratamiento de sonicación, produce el mejor rendimiento de HSC70. La calidad de la proteína inducida se estableció mediante "Western blotting". Conclusión. La proteína recombinante así obtenida permitió, generar anticuerpos policlonales que a su vez permiten detectar la proteína HSC70 natural en la membrana citoplasmática de diferentes células por inmunofluorescencia, en ELISA, en Western Blot y en pruebas de bloqueo de infección de rotavirus.

This study examines the nature of the involvement load (Laufer & Hulstijn, 2001) in second language (L2) lexical input processing through reading by considering the effects of the reader-based factors of L2 reading proficiency and background knowledge. The lexical input processing aspects investigated were lexical inferencing (search), attentional allocation during target word (TW) verification (evaluation), TW episodic memory after verification, TW retention, and changes in lexical input processing. This study also addresses the relationships between inferencing and retention as well as the relationships among the various phases of lexical input processing. A questionnaire on self-reported strategy use during the TW verification task was designed to examine motivation and cognitive involvement. A repeated-measures design was used with a cross-sectional sample of 35 adult L2 learners of Spanish. Participants read narratives (one more and one less familiar) that contained nonsense words. They guessed the meanings of the TWs. After reading all of the stories, participants completed an online inference verification task whose goal was to confirm or to correct guesses and to encourage deeper processing of TWs. This was followed by a test of TW episodic memory (yes/no verification) and a strategy questionnaire. Afterward, participants?completed two tests that measured receptive retention of meaning. Analyses reveal differential effects of the reader-based variables across the different aspects of lexical input processing and negative changes in lexical input processing due to an interaction between reading proficiency and background knowledge. Results illustrate how reader-based factors also affect learner involvement and lexical input processing. [ABSTRACT FROM AUTHOR]

The study examines the impact of topic familiarity and passage sight vocabulary on lexical inferencing and retention. Independent variables include (a) a topic familiarity questionnaire, and (b) a passage sight vocabulary test. A repeated-measures design was used with a cross-sectional sample of 35 adult L2 learners of Spanish. Ss read narratives (1 more and 1 less familiar) containing nonsense words. They guessed meanings of target words and rated degree of difficulty in guessing. After reading all stories, all participants completed an inference verification task to confirm or correct guesses, and to encourage deeper processing of target words. This was followed by two measures of retention: (a) translation production, and (b) translation recognition. Analyses reveal (a) robust effects of topic familiarity and passage sight vocabulary on lexical inferencing, (b) a significant interaction between topic familiarity and passage sight vocabulary on difficulty in lexical inferencing, and (c) robust effects of passage sight vocabulary on lexical retention and a significant effect of topic familiarity on lexical retention–translation recognition measure. The discussion concerns the significance of findings for lexical inferencing, processing, and retention through strategic reading tasks. [ABSTRACT FROM AUTHOR]

VOCABULARY IN A SECOND LANGUAGE: SELECTION, ACQUISITION, AND TESTING. Paul Bogaards and Batia Laufer (Eds.). Amsterdam: Benjamins, 2004. Pp. xiv + 233. $126.00 cloth, $42.95 paper.This volume consists primarily of papers that were presented at the second language vocabulary acquisition colloquium at Leiden University in March 2002 and represents a broad scope of quantitative studies by leading scholars in the field. It is organized under three different themes: “Selection,” “Acquisition,” and “Testing.” In the introduction, the editors briefly describe the contributions and follow with several pages that illustrate how the papers diverge on the conceptualization of central issues (e.g., the basic unit under investigation; aspects of the learning process, learning conditions, and time course of measurement; definitions of the construct of word knowledge). Finally, they add their own insightful perspectives on such issues, as well as helpful suggestions for further exploration, as a stimulus for future research. [ABSTRACT FROM AUTHOR]