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espanolSe evaluo el comportamiento en el secado de ensilado quimico de visceras de tilapia roja (Oreochromis sp), en funcion de la ubicacion de la muestra dentro de un secador solar directo pasivo y del espesor de la pelicula de la muestra. Se seleccionaron condiciones con base en criterios bromatologicos y microbiologicos, y parametros cineticos como el coeficiente de difusividad efectiva (Def). Luego se modelo la cinetica de secado, utilizando seis modelos empiricos y uno fenomenologico. Los resultados mostraron que muestras con un espesor de 2.40mm y ubicadas en posiciones cerca de la salida de aire, tienen mejor comportamiento durante el secado garantizando un contenido de humedad del producto menor a 12%, y entregando valores mas altos de Def. El modelo con el mejor ajuste fue el de Page, con mas altos valores del coeficiente de correlacion R2 y menores desviaciones comparado con los valores experimentales. Se concluye que la zona de ubicacion del producto en el secador y el espesor de la pelicula, afectan de manera significativa las caracteristicas del producto obtenido. EnglishDrying behavior of chemical silage of red tilapia viscera (Oreochromis sp) was evaluated, in a direct solar dryer, as a function of the location of the sample inside the dryer and of the thickness of the film sample. The experimental conditions were selected according to bromatological and microbiological criteria and kinetic parameters such as the effective diffusivity coefficient (Def). After that, the drying kinetics was modelled using six empirical models and one phenomenological model. The results showed that samples with 2.40mm of thickness have better behavior during drying achieving moisture content of less than 12% in the dried product in zones closer to the air exit, which in turn gave higher Def. The Page model provided the best fiiting of the data, with higher values of the correlation coefficient and lower deviations compared to experimental data. It is concluded that he location of the sample inside the dryer and the film thickness, significantly affect the characteristics of the product obtained.

[EN] Pterin (Ptr) is a model photosensitizer that acts mainly through type I mechanism and is able to photoinduce the one-electron oxidation of purine and pyrimidine nucleobases. However, under anaerobic conditions Ptr reacts with thymine (T) to form photoadducts (Ptr-T) but does not lead to the photodegradation of guanine (G), which is the nucleobase with the lowest ionization potential. Accordingly, G is thermodynamically able to reduce the radicals of the other nucleobases and has been described in this sense as the "hole sink" of the DNA double helix. Here we analyze by steady-state and time-resolved studies the effect of G in the anaerobic photosensitization of T by Ptr, using nucleotides and oligonucleotides of different sequences. We demonstrated that G is able to reduce T radicals but does not prevent the formation of Ptr-T adducts. Our results suggest that after the encounter between the excited Ptr and T, and completion of the electron transfer step, part of the radicals escape from the solvent cage, to further react with other species. However, a proportion of radicals do not escape and evolve to photoadducts before separation. We provide new evidence that contributes to understand the photosensitizing properties of Ptr in the absence of O-2, the mechanism of formation of photoadducts in the DNA and the protective role of G towards the photodamage in other nucleobases., The present work was partially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET-Grant P-UE 2017 22920170100100CO) , Agencia de Promocion Cientifica y Tecnologica (ANPCyT-Grant PICT 2015-1988, and PICT 2017-0925) , Universidad Nacional de La Plata (UNLP-Grant 11/X840) . Funding from the Program CSIC de Cooperacion Cientifica para el Desarrollo (iCOOP-Light project ref 20105CD0017) and Spanish Government (PGC2018-096684-B-I00) are gratefully acknowledged. S.E.R. and J.R.N.R. thanks ANPCyT and CONICET for doctoral research fellowships. A.M.R. thanks Universidad de Antioquia (Colombia) for research fellowship. C.L. and A.H.T. are research members of CONICET. V.L.V. is research member of CSIC.

Collections of 11 species of shallow water Polyplacophora from El Salvador were made in July 2002. Previously only five species had been documented in El Salvador: Chaetopleura lurida (Sowerby, 1832); Ischnochiton guatemalensis (Thiele, 1910); Ceratozona angusta (Thiele, 1909); Chiton stokesii (Broderip, 1832) and Acantochitona exquisita (Pilsbry, 1893). Of these, L. guatemalensis and A. exquisita were not collected in this census. Seven other species are reported here for El Salvador for the first time: Lepidochitona beanii (Carpenter, 1857); Ischnochiton dispar (Sowerby, 1832); Stenoplax limaciformis (Sowerby, 1832); Callistochiton expressus (Carpenter, 1865); Acanthochitona arragonites (Carpenter, 1867); A. ferreirai (Lyons, 1988) and A. hirudiniformis (Sowerby, 1832). The known geographic distribution of 1. dispar is extended to the north. An un-named species of Lepidochitona is briefly described.

En El Salvador se habían registrado los poliplacóforos Chaetopleura lurida (Sowerby, 1832); Ischnochiton guatemalensis (Thiele, 1910); Ceratozona angusta (Thiele, 1909); Chiton stokesii (Broderip, 1832) y Acantochitona exquisita (Pilsbry, 1893). Recolectamos quitones en aguas someras de El Salvador en julio del 2002, agragando a la lista a Lepidochitona beanii (Carpenter, 1857); Ischnochiton dispar (Sowerby, 1832); Stenoplax limaciformis (Sowerby, 1832); Callistochiton expressus (Carpenter, 1865); Acanthochitona arragonites (Carpenter, 1867); Acanthochitona ferreirai (Lyons, 1988) y Acanthochitona hirudiniformis (Sowerby, 1832). Ampliamos la distribución documentada de I. dispar hacia el norte y describimos brevemente una especie innominada de Lepidochitona.Chitons (Mollusca: Polyplacophora) from El Salvador, Central America. Collections of 11 species of shallow water Polyplacophora from El Salvador were made in July 2002. Previously only five species had been documented in El Salvador: Chaetopleura lurida (Sowerby, 1832); Ischnochiton guatemalensis (Thiele, 1910); Ceratozona angusta (Thiele, 1909); Chiton stokesii (Broderip, 1832) and Acantochitona exquisita (Pilsbry, 1893). Of these, I. guatemalensis and A. exquisita were not collected in this census. Seven other species are reported here for El Salvador for the first time: Lepidochitona beanii (Carpenter, 1857); Ischnochiton dispar (Sowerby, 1832); Stenoplax limaciformis (Sowerby, 1832); Callistochiton expressus (Carpenter, 1865); Acanthochitona arragonites (Carpenter, 1867); A. ferreirai (Lyons, 1988) and A. hirudiniformis (Sowerby, 1832). The known geographic distribution of I. dispar is extended to the north. An un-named species of Lepidochitona is briefly described. Rev. Biol. Trop. 55 (1): 171-176. Epub 2007 March. 31.