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La criopreservación de semen produce daños celulares a nivel de membranas plasmáticas, mitocondria y ADN debido principalmente a la formación de cristales de hielo intra y extracelular; así como, al estrés osmótico y oxidativo generado. Para minimizar estos daños se utilizan medios diluyentes que simulan las características fisiológicas del semen y contienen sustancias crioprotectoras, las cuales con ayuda de algunos antioxidantes proporcionan una mayor supervivencia espermática posdescongelación y mejora en las tasas de motilidad y fertilidad. La adición de antioxidantes enzimáticos como superóxido dismutasa, catalasa y peróxidasa durante el proceso de criopreservación de células espermáticas en peces, no favorece las tasas de motilidad espermática posdescongelación ni de fertilización en las especies trucha arco iris y de arroyo, mientras que los no enzimáticos (MDPA, BHT, cisteína, propóleo, ácido ascórbico, lisina y carnitina) las mejoran de forma significativa en especies como esturión beluga, carpa común, esturión ruso y trucha arco iris.
About the author
María del Pilar Rodríguez Becerra es bióloga de la UPTC. Desarrollo investigación en la UJTLJavier Hernández Fernández es profesor Asociado II de la Universidad Jorge Tadeo Lozano y director del Grupo de investigación "Gembimol".Alexander Nivia Osuna, Profesor UNAD.
Summary
They are one of the world's legendary couples. We can't think of one without thinking of the other. Simone de Beauvoir and Jean-Paul Sartre -- those passionate, freethinking existentialist philosopher-writers -- had a committed but notoriously open union that generated no end of controversy. With Tete-a-Tete, distinguished biographer Hazel Rowley offers the first dual portrait of these two colossal figures and their intense, often embattled relationship. Through original interviews and access to new primary sources, Rowley portrays them up close, in their most intimate moments.
We witness Beauvoir and Sartre with their circle, holding court in Paris cafes. We learn the details of their infamous romantic entanglements with the young Olga Kosakiewicz and others; of their efforts to protest the wars in Algeria and Vietnam; and of Beauvoir's tempestuous love affair with Nelson Algren. We follow along on their many travels, involving meetings with dignitaries such as Roosevelt, Khrushchev, and Castro. We listen in on the couple's conversations about Sartre's Nausea, Being and Nothingness, and Words, and Beauvoir's The Second Sex, The Mandarins, and her memoirs. And we hear the anguished discussions that led Sartre to refuse the Nobel Prize.
The impact of their writings on modern thought cannot be overestimated, but Beauvoir and Sartre are remembered just as much for the lives they led. They were brilliant, courageous, profoundly innovative individuals, and Tete-a-Tete shows the passion, energy, daring, humor, and contradictions of their remarkable, unorthodox relationship. Theirs is a great story -- and a great story is precisely what Beauvoir and Sartre most wanted their lives to be.
Additional text
"[Rowley] draws from vast stores of published and unpublished writings, correspondence and interviews."
