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Reactive oxygen species (ROS) have been proposed as one of the main causes of the impairment of fish spermatozoa integrity and functionality during cryopreservation. The high content of unsaturated fatty acids in sperm cells and the low antioxidant capacity of diluted semen are key factors in making sperm cells susceptible to ROS attacks. For this reason, some recent studies have determined the antioxidant status of the seminal plasma and spermatozoa of fish species. Additionally, some studies have evaluated the effects of antioxidants on post-thaw sperm quality. Although ROS are certainly involved in sperm damage, other factors, such as ice crystal formation, seem to play a crucial role in cryodamage. This challenge has not yet been resolved because both the endogenous antioxidant capacity of the semen and its response to different supplementation practices seem to present specific inter-and intraspecies characteristics and effects. This review summarises knowledge on antioxidant defence and oxidative stress in fish semen, as well as antioxidant supplementation in cryopreservation media, in order to establish perspectives for future studies.

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The following article is the product of research conducted at the Universidad de la Frontera with regard to the integration into the profession of graduates from the teaching programs in the Faculty of Education and Humanities. A lot of literature exists regarding the socialization of teachers, new teachers and the induction of teaching professionals, from which we selected the proposal of the Dutchman Vonk, J.H.C. who suggests four models of professional integration: "Sink or Swim", "Collegial", "Mandated Competence" and the "Formalized Protected Mentor Model". Sample information of graduate students was taken with regard to the different dimensions of professional performance. The results were ambivalent, with both solid general abilities and weaknesses in specific areas of competence. Furthermore, two structural situations were confirmed: on the one hand, the type of establishment determines the kind of integration, and on the other, the absence of an institutionalized mechanism of professional induction.

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