Effects of photoperiod on epididymal and sperm morphology in a wild rodent, the viscacha (Lagostomus maximus maximus)

The viscacha (Lagostomus maximus maximus) is a seasonal South American wild rodent. The adult males exhibit an annual reproductive cycle with periods of maximum and minimum gonadal activity. Four segments have been identified in the epididymis of this species: initial, caput, corpus, and cauda. The main objective of this work was to relate the seasonal morphological changes observed in the epididymal duct with the data from epididymal sperm during periods of activity and gonadal regression using light and scanning electron microscopy (SEM). Under light and electron microscopy, epididymal corpus and cauda showed marked seasonal variations in structural parameters and in the distribution of different cellular populations of epithelium. Initial and caput segments showed mild morphological variations between the two periods. Changes in epididymal sperm morphology were observed in the periods analyzed and an increased number of abnormal gametes were found during the regression period. During this period, anomalies were found mainly in the head, midpiece, and neck, while in the activity period, defects were found only in the head. Our results confirm that the morphological characteristics of the epididymal segments, as well as sperm morphology, undergo significant changes during the reproductive cycle of Lagostomus.Fil: Cruceño, A. M.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Cátedra de Histología; ArgentinaFil: De Rosas, J. C.. Consejo Nacional de Investigaciones Científicas y Tecnicas. Centro Cientifico Tecnologico Mendoza. Instituto Histologia y Embriologia de Mendoza "Dr. M. Burgos"; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas; ArgentinaFil: Foscolo, Mabel Rosa. Consejo Nacional de Investigaciones Científicas y Tecnicas. Centro Cientifico Tecnologico Mendoza. Instituto Histologia y Embriologia de Mendoza "Dr. M. Burgos"; ArgentinaFil: Chaves, E. M.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Cátedra de Histología; ArgentinaFil: Scardapane, L.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Cátedra de Histología; ArgentinaFil: Dominguez, S.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Cátedra de Histología; ArgentinaFil: Aguilera Merlo, C.. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Cátedra de Histología; Argentin

Analysis of syngas methanation for bio-SNG production from wastes: kinetic model development and pilot scale validation

Bio-substitute natural gas (or bio-SNG) produced from gasification of waste fuels and subsequent methanation of the product gas could play a crucial role in the decarbonisation of heating and transportation, and could be a vital part of the energy mix in the coming decades. Although the methanation of trace quantities of carbon oxides has been practiced commercially for many years, methanation from syngas poses a more severe problem due to the high and unstable concentrations of reactants in the produced gas. In this work, a low-Ni methanation cat alyst was tested in a differential reactor to derive a kinetic model that could determine a practical operating scheme for the first methanation step of a typical bio-SNG process. The model, comprising water gas shift and methanation reactions, along with their reverse reactions, was used for realistic modelling of the methanation process using high quality syngas, obtained from steam-oxygen gasification of wastes and gas plasma conversion, and to better determine the operation conditions in the first reactor of a bio-SNG pilot plant in Swindon (UK). The tests undertaken show that the catalyst was performing as expected using the waste-derived syngas at industrially relevant conditions, when compared to predictions of models derived from works using bottled gases. This gives confidence that the same approach can be used for the detailed design and operation of once through methanation reactor elements and process system configuration for bio-SNG production at larger scale

DISTRIBUCIÓN DE LOS MASTOCITOS EN LAS GLÁNDULAS SALIVALES MAYORES DE RATA

Los mastocitos son células del tejido conectivo ampliamente distribuidas en la mucosa digestiva yrespiratoria, especialmente cerca de sitios de respuesta inmune. El presente estudio se efectuó con elpropósito de evaluar la distribución de los mastocitos en las glándulas salivales mayores (parótida,submaxilar y sublingual) de rata. Las muestras de tejido glandular fueron incluidas en parafina y loscortes histológicos obtenidos se colorearon con Azul alcian-safranina y Azul de Toluidina. Posteriormentese efectuó la cuantificación de mastocitos/mm2 considerando dos áreas glandulares: el estromaintralobulillar y el interlobulillar. Los resultados no muestran variaciones significativas en la población demastocitos al comparar las tres glándulas (p>0,05), pero si se encontró una mayor presencia demastocitos en relación con la vía excretora principal. Los resultados en conjunto sugieren una activaparticipación de los mastocitos en los mecanismos de detección de antígenos que ingresan a lasglándulas salivales y su estrecha relación con otras células captadoras de antígenos como las célulasdendríticas.Abstract: Mast cells (MT) are connective tissue cells widely distributed throughout thebody, especially in immune mucosal response sites like the digestive and air way tract.The aim of the present study was to find the number and the pattern of distribution and possibledifferences in mast cell population present in the mayor salivary glands (parotid, submandibular andsublingual glands) of rats. Fragments from salivary glands were collected, processed an included inparaffin wax, cut and stained with alcian blue-safranin and toluidine blue. The total number of MT wascounted to estimate the mm2 population from both intralobulillar and interlobulillar stroma tissues.Statistical analysis showed not significant differences (p> 0.05) between the three analysed glands.Numerous mast cells were located around salivary secretory ducts, in close association The resultssuggest that MT play a relevant role in salivary antigen detection and that there is a close cooperationwith other antigen professional presenting cells like dendritic cells