Estudios morfológicos y ultraestructurales en esporas de Cyatheaceae del Cono Sur

Se estudió la morfología y la ultraestructura de las esporas de las Cyatheaceae del Cono Sur (Argentina, Chile, Paraguay, Uruguay y los tres estados del sur de Brasil). Para realizar este trabajo se utilizó material de herbario y fresco, coleccionado en viajes de campo. Se usaron diversas técnicas de fijación y tinciones diferenciales y las observaciones se realizaron con microscopio óptico y electrónico de barrido y de transmisión. Las Cyatheaceae que crecen en el área de estudio corresponden a tres géneros, que pueden ser diferenciados por la morfología de las escamas de la base del pecíolo. En base a observaciones propias en el campo, la consulta de herbarios y la revisión bibliográfica, se pudo determinar la presencia de 7 especies de Cyathea, 4 de Alsophila y 1 de Sphaeropteris. Se actualizó la distribución de los taxa y se excluyó del área en estudio a Alsophila cuspidata, previamente citada por otros autores. Como características generales las esporas son triletes, triangulares en vista polar, con los lados rectos a cóncavos y los ángulos redondeados. En vista ecuatorial son plano-hemisféricas, convexohemisféricas o cónico-subcónicas. En todos los casos el exosporio presenta dos capas, una interna delgada y una externa más gruesa, menos electrodensa, con margen entero o perforado y canales y cavidades. El perisporio tiene dos capas que varían, según el género, en grosor, ornamentación estratificación y estructura. Las esporas de Cyathea se caracterizan por presentar un perisporio delgado, castaño oscuro al microscopio óptico, formado por una red tridimensional de cordones con los extremos distales libres o unidos formando espínulas. En secciones delgadas de la esporodermis observadas con microscopio electrónico de transmisión se diferencian dos capas en el perisporio, la interna con dos estratos y la externa delgada y uniestratificada. El exosporio al microscopio óptico es grueso, amarillo y la superficie, según la especie, es psilada, perforada o verrucosa. El perisporio de Alsophila es castaño oscuro al microscopio óptico y la ornamentación compuesta por lomos de superficie lisa o crestada, esta última de diversas características. Sobre la superficie se observan glóbulos. A nivel ultraestructural presenta dos capas, la interna con tres estratos y la externa uniestratificada. El exosporio al microscopio óptico es amarillo a castaño claro y psilado. Sphaeropteris tiene un perisporio castaño oscuro al microscopio óptico, la ornamentación se caracteriza por la presencia de lomos de margen equinado. Se observan además glóbulos de distinto tamaño sobre la superficie. La estratificación de la pared es similar a la de Alsophila, aunque con diferencias ornamentales y ultraestructurales en la capa externa del perisporio. El exosporio es castaño claro al microscopio óptico y la superficie es psilada. Los resultados obtenidos en el presente trabajo reflejan la homogeneidad palinológica para cada género. Se aportan caracteristicas palinológicas superficiales y estructurales que permiten la diferenciación a nivel específico. Asimismo, se pone de manifiesto que la superficie y ultraestructura de las esporas de las Cyatheaceae del área podrían reflejar las tendencias evolutivas de la Familia y aportarían datos que avalan las hipótesis filogenéticas recientes. Los resultados obtenidos del análisis de la ultraestructura y subestructura de la pared de las esporas, como la presencia de superficies aplanadas y glóbulos superficiales, cordones con una subestructura compleja dispuestos de diferente manera en cada estrato del perisporio y canales en el perisporio y exosporio, ponen en evidencia la complejidad de la esporodermis. Tal complejidad estaría relacionada con la función que cumple la pared durante la diferenciación de las esporas en formación, la protección y dispersión de las esporas maduras y el mecanismo de abertura durante la germinación. Las descripciones morfológicas, basadas en diferentes metodologías utilizadas al trabajar en material, vivo o de herbario, brindan importante información a la botánica morfológica interpretativa y aportan datos a otras disciplinas afines, como ser el mejoramiento de las afinidades botánicas en paleobotánica.Facultad de Ciencias Naturales y Muse

A experiência da virtualização das atividades da incubadora universitária MINERVA-UNLP no contexto da Covid-19

Con el advenimiento del Aislamiento Social, Preventivo y Obligatorio dictado en el mes de marzo del 2020 por el Gobierno Nacional, los argentinos comenzamos vivir un contexto inédito. Las consecuencias sanitarias, sociales y económicas no tardaron en llegar y las instituciones del Estado comenzaron a tomar medidas para morigerar la situación. La Universidad Nacional de La Plata no estuvo exenta y tomó cartas en el asunto, desarrollando una serie de estrategias que impactaron por su rápida respuesta. La Incubadora Minerva de Emprendimientos fue clave en la conexión con el sistema productivo regional y, a través de ella, se realizaron acciones para canalizar los diversos emprendimientos de muchos emprendedores, quienes querían aportar en el combate de la pandemia. En este sentido, se realizó las Convocatoria “Tu idea Suma”, en la que se presentaron 63 proyectos, la mayoría de los cuales fueron canalizados para que pudieran ser efectivos. Pensando en la realidad post pandemia, se convocó al concurso: “¿- Cambio Climático = Pandemias?”, considerando que uno de los grandes problemas generadores de enfermedades peligrosas es la falta de cuidado del ambiente. Se readecuaron las actividades de internacionalización programadas, con el objetivo de potenciar las acciones futuras, tendientes a mitigar los efectos de esta crisis. Además, se trabajó en la articulación de las PyMEs y los emprendedores con las líneas de financiamiento que fue presentando la Secretaría de Producción del Gobierno Nacional. Estas medidas han formado parte substancial en la respuesta institucional.With the advent of Social, Preventive and Mandatory Isolation issued in March 2020 by the National Government, Argentines began to experience an unprecedented context. The health, social and economic consequences were not long in coming and the State institutions began to take measures to mitigate the situation. The National University of La Plata was not exempt and took action on the matter, developing a series of strategies that impacted due to its quick response. The Minerva Entrepreneurship Incubator was key in connecting with the regional production system and, through it, actions were carried out to channel the various undertakings of many entrepreneurs, who wanted to contribute to the fight against the pandemic. In this sense, the Call "Your idea Sum" was held, in which 63 projects were presented, most of which were channeled so that they could be effective. Thinking about the post-pandemic reality, the contest was called: "- Climate Change = Pandemics?", Considering that one of the great problems that generates dangerous diseases is the lack of care for the environment. The programmed internationalization activities were readjusted, with the aim of promoting future actions aimed at mitigating the effects of this crisis. In addition, work was carried out on the articulation of SMEs and entrepreneurs with the financing lines that were presented by the Ministry of Production of the National Government. These measures have been a substantial part of the institutional response.Com o advento do Isolamento Social, Preventivo e Obrigatório, expedido em março de 2020 pelo Governo Nacional, os argentinos passaram a vivenciar um contexto inédito. As consequências para a saúde, sociais e econômicas não tardaram a chegar e as instituições do Estado começaram a tomar medidas para mitigar a situação. A Universidade Nacional de La Plata não se eximiu e agiu sobre o assunto, desenvolvendo uma série de estratégias que impactaram devido à sua rápida resposta. A Incubadora de Empreendedorismo Minerva foi fundamental para se conectar com o sistema produtivo regional e, por meio dela, foram realizadas ações para canalizar os diversos empreendimentos de muitos empresários, que queriam contribuir no combate à pandemia. Nesse sentido, foi realizada a Chamada “Sua Ideia Summa”, na qual foram apresentados 63 projetos, a maioria deles canalizados para que pudessem ser efetivos. Pensando na realidade pós-pandêmica, o concurso foi denominado: “- Mudanças Climáticas = Pandemias?”, Considerando que um dos grandes problemas que geram doenças perigosas é a falta de cuidado com o meio ambiente. As atividades de internacionalização programadas foram reajustadas, com o objetivo de promover ações futuras visando mitigar os efeitos desta crise. Adicionalmente, foi realizado um trabalho de articulação das PMEs e empresários com as linhas de financiamento que estavam a ser apresentadas pelo Ministério da Produção do Governo Nacional. Essas medidas têm sido uma parte substancial da resposta institucional.Instituto de Investigaciones en Educación Superio

A experiência da virtualização das atividades da incubadora universitária MINERVA-UNLP no contexto da Covid-19

With the advent of Social, Preventive and Mandatory Isolation issued in March 2020 by the National Government, Argentines began to experience an unprecedented context. The health, social and economic consequences were not long in coming and the State institutions began to take measures to mitigate the situation. The National University of La Plata was not exempt and took action on the matter, developing a series of strategies that impacted due to its quick response. The Minerva Entrepreneurship Incubator was key in connecting with the regional production system and, through it, actions were carried out to channel the various undertakings of many entrepreneurs, who wanted to contribute to the fight against the pandemic. In this sense, the Call "Your idea Sum" was held, in which 63 projects were presented, most of which were channeled so that they could be effective. Thinking about the post-pandemic reality, the contest was called: "- Climate Change = Pandemics?", Considering that one of the great problems that generates dangerous diseases is the lack of care for the environment. The programmed internationalization activities were readjusted, with the aim of promoting future actions aimed at mitigating the effects of this crisis. In addition, work was carried out on the articulation of SMEs and entrepreneurs with the financing lines that were presented by the Ministry of Production of the National Government. These measures have been a substantial part of the institutional response.Con el advenimiento del Aislamiento Social, Preventivo y Obligatorio dictado en el mes de marzo del 2020 por el Gobierno Nacional, los argentinos comenzamos vivir un contexto inédito. Las consecuencias sanitarias, sociales y económicas no tardaron en llegar y las instituciones del Estado comenzaron a tomar medidas para morigerar la situación. La Universidad Nacional de La Plata no estuvo exenta y tomó cartas en el asunto, desarrollando una serie de estrategias que impactaron por su rápida respuesta. La Incubadora Minerva de Emprendimientos fue clave en la conexión con el sistema productivo regional y, a través de ella, se realizaron acciones para canalizar los diversos emprendimientos de muchos emprendedores, quienes querían aportar en el combate de la pandemia. En este sentido, se realizó las Convocatoria “Tu idea Suma”, en la que se presentaron 63 proyectos, la mayoría de los cuales fueron canalizados para que pudieran ser efectivos. Pensando en la realidad post pandemia, se convocó al concurso: “¿Cambio Climático = Pandemias?”, considerando que uno de los grandes problemas generadores de enfermedades peligrosas es la falta de cuidado del ambiente. Se readecuaron las actividades de internacionalización programadas, con el objetivo de potenciar las acciones futuras, tendientes a mitigar los efectos de esta crisis. Además, se trabajó en la articulación de las PyMEs y los emprendedores con las líneas de financiamiento que fue presentando la Secretaría de Producción del Gobierno Nacional. Estas medidas han formado parte substancial en la respuesta institucional.Com o advento do Isolamento Social, Preventivo e Obrigatório, expedido em março de 2020 pelo Governo Nacional, os argentinos passaram a vivenciar um contexto inédito. As consequências para a saúde, sociais e econômicas não tardaram a chegar e as instituições do Estado começaram a tomar medidas para mitigar a situação. A Universidade Nacional de La Plata não se eximiu e agiu sobre o assunto, desenvolvendo uma série de estratégias que impactaram devido à sua rápida resposta. A Incubadora de Empreendedorismo Minerva foi fundamental para se conectar com o sistema produtivo regional e, por meio dela, foram realizadas ações para canalizar os diversos empreendimentos de muitos empresários, que queriam contribuir no combate à pandemia. Nesse sentido, foi realizada a Chamada “Sua Ideia Summa”, na qual foram apresentados 63 projetos, a maioria deles canalizados para que pudessem ser efetivos. Pensando na realidade pós-pandêmica, o concurso foi denominado: “- Mudanças Climáticas = Pandemias?”, Considerando que um dos grandes problemas que geram doenças perigosas é a falta de cuidado com o meio ambiente. As atividades de internacionalização programadas foram reajustadas, com o objetivo de promover ações futuras visando mitigar os efeitos desta crise. Adicionalmente, foi realizado um trabalho de articulação das PMEs e empresários com as linhas de financiamento que estavam a ser apresentadas pelo Ministério da Produção do Governo Nacional. Essas medidas têm sido uma parte substancial da resposta institucional

Estudios morfológicos y ultraestructurales en esporas de Cyatheaceae del Cono Sur

Tesis presentada para optar al Grado de Doctor en Ciencias NaturalesFil: Márquez, Gonzalo Javier. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeografic Province that produce monolete spores and its systematic implications (I): <i>Blotiella lindeniana</i>, <i>Histiopteris incisa</i> and <i>Paesia glandulosa</i>

The genera of Dennstaedtiaceae have sporophytes with very different morphological characteristics between each other, and this feature has made difficult the systematic circumscription of the family. This reason makes necessary the study of new characters that allow a better understanding of the relations within the group. The spore morphology and wall structure of Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa from the Paranaense Phytogeographic Province were studied using light microscope, and scanning and transmission electron microscope. The exospore has two layers and, according to the species, the exospore surface bears pila, echinae, verrucae, bacula and tubercles. The perispore has two or three layers and its surface is psilate, baculate or rugulate. The variability found in the sculpture of the spores and their stratification and ultrastructure of perispore reflects the morphological differences observed in the sporophyte of the species studied. Additionally, while the stratification and ultrastructure of the exospore is shared by the Dennstaedtiaceae species, their ornamentation could be a character to distinguish species into the clade “hypolepidoide”. The finding of spores with similar characteristics in phylogenetically unrelated families allows us to suggest that palynological features do not have an evolutionary value to establish relationships between groups above the genus level.Facultad de Ciencias Naturales y Muse

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeographic Province that produce Trilete spores II: Microlepia speluncae and Pteridium arachnoideum

The spore morphology and wall ultrastructure of Microlepia speluncae and Pteridium arachnoideum from the Paranaense Province were analyzed with LM, SEM and TEM and a comparative analysis was carried out. In both species the spores are covered by a three-dimensional network of threads branched and fused, tangentially arranged to the surface, and some free-end threads are also seen. The species were differentiated by morphology and the frequency of threads fusion and the networks distribution on the surface of the spores. In both species the exospore is two-layered in section, both layers are traversed by single or branched channels. The perispore is three-layered in section: the inner layer is adhered to the exospore, the middle layer is formed of a three-dimensional network of threads and the outer layer is discontinuous. The perispore ultrastructure of Microlepia speluncae was interpreted as formed of helical subunits displayed around a central channel. The spore morphology and perispore ultrastructure allow differentiating Microlepia from Pteridium but also to the other Dennstaedtiaceae genera that grow in the Paranaense Province. The results obtained allow establishing relationships that let us recognize different groups and gave a new reference to get a better knowledge of the family.Facultad de Ciencias Naturales y Muse

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeografic Province that produce monolete spores and its systematic implications (I): <i>Blotiella lindeniana</i>, <i>Histiopteris incisa</i> and <i>Paesia glandulosa</i>

The genera of Dennstaedtiaceae have sporophytes with very different morphological characteristics between each other, and this feature has made difficult the systematic circumscription of the family. This reason makes necessary the study of new characters that allow a better understanding of the relations within the group. The spore morphology and wall structure of Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa from the Paranaense Phytogeographic Province were studied using light microscope, and scanning and transmission electron microscope. The exospore has two layers and, according to the species, the exospore surface bears pila, echinae, verrucae, bacula and tubercles. The perispore has two or three layers and its surface is psilate, baculate or rugulate. The variability found in the sculpture of the spores and their stratification and ultrastructure of perispore reflects the morphological differences observed in the sporophyte of the species studied. Additionally, while the stratification and ultrastructure of the exospore is shared by the Dennstaedtiaceae species, their ornamentation could be a character to distinguish species into the clade “hypolepidoide”. The finding of spores with similar characteristics in phylogenetically unrelated families allows us to suggest that palynological features do not have an evolutionary value to establish relationships between groups above the genus level.Facultad de Ciencias Naturales y Muse

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeographic Province that produce Trilete spores II: Microlepia speluncae and Pteridium arachnoideum

The spore morphology and wall ultrastructure of Microlepia speluncae and Pteridium arachnoideum from the Paranaense Province were analyzed with LM, SEM and TEM and a comparative analysis was carried out. In both species the spores are covered by a three-dimensional network of threads branched and fused, tangentially arranged to the surface, and some free-end threads are also seen. The species were differentiated by morphology and the frequency of threads fusion and the networks distribution on the surface of the spores. In both species the exospore is two-layered in section, both layers are traversed by single or branched channels. The perispore is three-layered in section: the inner layer is adhered to the exospore, the middle layer is formed of a three-dimensional network of threads and the outer layer is discontinuous. The perispore ultrastructure of Microlepia speluncae was interpreted as formed of helical subunits displayed around a central channel. The spore morphology and perispore ultrastructure allow differentiating Microlepia from Pteridium but also to the other Dennstaedtiaceae genera that grow in the Paranaense Province. The results obtained allow establishing relationships that let us recognize different groups and gave a new reference to get a better knowledge of the family.Facultad de Ciencias Naturales y Muse

Palynological analysis of Dennstaedtiaceae taxa from the Paranaense Phytogeografic Province that produce monolete spores and its systematic implications (I): <i>Blotiella lindeniana</i>, <i>Histiopteris incisa</i> and <i>Paesia glandulosa</i>

The genera of Dennstaedtiaceae have sporophytes with very different morphological characteristics between each other, and this feature has made difficult the systematic circumscription of the family. This reason makes necessary the study of new characters that allow a better understanding of the relations within the group. The spore morphology and wall structure of Blotiella lindeniana, Histiopteris incisa and Paesia glandulosa from the Paranaense Phytogeographic Province were studied using light microscope, and scanning and transmission electron microscope. The exospore has two layers and, according to the species, the exospore surface bears pila, echinae, verrucae, bacula and tubercles. The perispore has two or three layers and its surface is psilate, baculate or rugulate. The variability found in the sculpture of the spores and their stratification and ultrastructure of perispore reflects the morphological differences observed in the sporophyte of the species studied. Additionally, while the stratification and ultrastructure of the exospore is shared by the Dennstaedtiaceae species, their ornamentation could be a character to distinguish species into the clade “hypolepidoide”. The finding of spores with similar characteristics in phylogenetically unrelated families allows us to suggest that palynological features do not have an evolutionary value to establish relationships between groups above the genus level.Facultad de Ciencias Naturales y Muse

Influencia de asfaltenos y resinas en la viscosidad de petróleos bituminosos utilizables como pinturas asfálticas de imprimación

Los crudos extrapesados procedentes del área Machete (Venezuela) son materiales de consistencia blanda o fluida, por lo que se salen del campo en el que normalmente se aplica el ensayo de penetración a productos asfálticos según el mé- todo ASTM D-5 (1), cuyo límite máximo es 30 mm, y pueden ser utilizados como pinturas asfálticas de imprimación. Al igual que otros productos asfálticos, estos petróleos son químicamente una mezcla de numerosos hidrocarburos nafténicos, parafínicos, aromáticos y compuestos heterocíclicos que contienen azufre, nitrógeno, oxígeno, etc. Están compuestos por una fase pesada y otra de aceites malténicos que, además de los hidrocarburos naturales empleados como aditivos, actúa a modo de fluidificante volátil. La primera fase se describe como una mezcla de asfalten~ o susta,ncias complejas de alto peso molecular, insoluble en hidrocarburos parañnicos y soluble en compuestos aromáticos como el benceno; la segunda es descrita como una mezcla de resinas y otros hidrocarburos. Estas dos fases constituyen un sistema coloidal. En este trabajo se presentan los resultados experimentales del efecto de la proporción de asfaltenos y resinas en la viscosidad de tales crudos, con vista a su aplicación como materiales imprimadores. Los experimentos se realizaron en un reactor batch marca Parr en una atmósfera de nitrógeno yempleando n-heptano como disolvente. Una vez precipitados los asfaltenos a partir de las muestras utilizadas y, seguidamente, de la fracción de maltenos obtenida, se separaron las resinas. Al comparar los resultados obtenidos, se encontró que los asfaltenos eran responsables de las características estructurales y de consistencia del vehículo, mientras las resinas le proporcionan propiedades aglutinantes y los aceites malténicos actúan como disolventesThe bituminous crude from the Machete/ Venezuela/ area/ which has such a fluid consistency thatitfalls outside the normalscope of the A5TM o-s (1) penetration tes~ exceeding the 3D-mm ceiling specified in that standar~ and can be used as an asphaltprimer: Like other asphaltproducts/ these materials are -chemically speaking- a mix ofnumerous naphtheni~ paraffinic and aromatic hydrocarbons and heterocyc/ic compounds containing sulphur, nitrogen/ oxygen and so on. They have a dense and a malthene Ol'l phase which/ along with the natural hydrocarbons additives usedin these products/ acts as a volatile fluidizer: The former is described as a mix of asphaltenes: comple~ high mo/ecular weight substances that are insolub/e in paraffinichydrocarbons andsoluble in aromatic compounds such as benzene. The malthene oilphase/ in turn/ consists in a mix of resins and hydrocarbons and together the two constitute a colloida/system. The experiments discussedin thepresentpaper were conducted to determine the effect of the proportion of asphaltenes and resin oils on the viscosity ofsuch bituminous crude emulsions/ with a view to their use as primers. These experiments were run in a Parr batch reactor in a nitrogen atmosphere using n-heptane as a solvent. The resins were separated after the asphaltenes precipitated from the samples and subsequently from the malthene fraction obtained. The results showed that the asphaltenes account for the structural characteristics and consistency ofthe medium and the resin oils for its cohesive properties/ the malthene oils act as solvent