The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Javier Reina-tosina - One of the best experts on this subject based on the ideXlab platform.
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Transverse magnetic waves in myelinated nerves
2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1Co-Authors: M.m. Villapecellin-cid, Laura M. Roa, Javier Reina-tosinaAbstract:The structure of myelinated axons is quite similar to that of a high-loss coaxial cable. An electromagnetic analysis of TM waves shows that distributed effects cannot be neglected. The attenuation and phase constants are obtained as a function of frequency. Predicted finite wave delay in the Internodal Segment approaches measurements.
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Ranvier nodes impedance match with Internodal transmission lines of myelinated axons
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 1Co-Authors: M.m. Villapecellin-cid, L. Rao, Javier Reina-tosinaAbstract:Most myelinated axon models are not concerned with Internodal Segments delay. Distributed effects could be thought as the cause of these delays. In this paper we use a myelinated axon model which takes into account both the distributed nature of the Internodal Segment and the loading effect of Ranvier nodes. Impedance match of Ranvier nodes is researched. We provide a detailed frequency domain analysis of axon behavior within the context of our model. Results show that Ranvier nodes are roughly matched with Internodal Segments.
E A Siril - One of the best experts on this subject based on the ideXlab platform.
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auxin and nutritional stress coupled somatic embryogenesis in oldenlandia umbellata l
Physiology and Molecular Biology of Plants, 2017Co-Authors: S Saranya R Krishnan, E A SirilAbstract:Somatic embryos were induced from Internodal Segment derived callus of Oldenlandia umbellata L., in MS medium supplemented with different concentrations of 2,4-Dichlorophenoxy acetic acid (2,4-D). Initially calli were developed from internodes of microshoots inoculated in 2.5 µM NAA supplemented medium. Then calli were transferred to 2,4-D added medium for somatic embryogenesis. Nutritional stress coupled with higher concentration of 2,4-D triggered somatic embryogenesis. Nutritional stress was induced by culturing callus in a fixed amount of medium for a period up to 20 weeks without any external supply of nutrients. Addition of 2.5 µM 2,4-D gave 100% embryogenesis within 16 weeks of incubation. Callus mass bearing somatic embryos were transferred to germination medium facilitated production of in vitro plantlets. MS medium supplemented with 2.5 µM benzyl adenine and 0.5 µM α-naphthalene acetic acid produced 15.33 plants per culture within 4 weeks of culture. Somatic embryo germinated plants were then hardened and transferred to green house.
Ribeiro, Leonardo Monteiro - One of the best experts on this subject based on the ideXlab platform.
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Técnicas de cultivo in vitro e microenxertia ex vitro visando a eliminação do Cowpea Aphid-Borne Mosaic virus em Maracujazeiro-Azedo
2009Co-Authors: Ribeiro, Leonardo MonteiroAbstract:O maracujazeiro-azedo (Passiflora edulis Sims f. flavicarpa Deg.) é uma das principais frutíferas brasileiras e seu cultivo apresenta boas perspectivas de expansão. O desenvolvimento da cultura tem sido dificultado por doenças, especialmente a doença do endurecimento dos frutos, causada pelo Cowpea aphid-borne mosaic virus (CABMV). A eliminação de vírus pela cultura de tecidos tem sido uma alternativa viável para muitas espécies e pode contribuir para a propagação vegetativa de genótipos superiores. O presente trabalho foi realizado com o objetivo de estudar a organogênese in vitro em plantas de maracujazeiro amarelo infectadas com o Cowpea aphid-borne mosaic virus (CABMV) e avaliar o efeito de meios de cultura utilizados sobre o ponto da enxertia na microenxertia ex vitro visando a eliminação do vírus CABMV. No estudo da organogênese foram avaliados cinco acessos: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) e quatro fontes de explantes: ápice caulinar, Segmento Internodal, Segmento nodal e fragmento foliar. Foi utilizado para indução o meio MS suplementado por 2 mg.L-1 de 6-benzilaminopurina (BAP). O Segmento nodal apresentou melhor desempenho no cultivo enquanto os piores resultados foram obtidos com o fragmento foliar. Os acessos apresentaram comportamento semelhante em relação ao percentual de explantes organogênicos e à produção de brotos. Foram observados em cortes histológicos meristemóides em explantes de nó e ápice. No trabalho envolvendo a eliminação de vírus por microenxertia ex vitro, ápices caulinares provenientes de plantas do acesso MAR-2050 infectadas foram microenxertados em plântulas obtidas pela germinação de sementes e cultivadas em substrato comercial em condição de laboratório. Foram conduzidos experimentos com a microenxertia realizada no hipocótilo e no epicótilo e testados cinco meios de cultura como adjuvantes, aplicados no ponto da enxertia. O índice de pegamento médio foi de 27,22 % quando a microenxertia foi realizada no hipocótilo e 32,22 % quando realizada no epicótilo. Na microenxertia realizada no hipocótilo não houve efeito da aplicação de meios de cultura ou reguladores de crescimento. Na microenxertia realizada no epicótilo o meio MS suplementado com 3% de sacarose, 10 mg.L-1 de tiamina; 1 mg.L-1 de piridoxina; 1 mg.L-1 de ácido nicotínico; 100 mg L-1 de mio-inositol e 2 gL-1 de Phytagel, (meio básico), acrescido de 0,1 mg.L-1 de ácido 3-indolbutírico (AIB) e 1 mg.L-1 de 6-benzilaminopurina (BAP) proporcionou 53,3% de pegamento e foi superior aos demais tratamentos, com exceção do tratamento meio básico suplementado com 2 mg L-1 xvi de BAP. O mesmo tratamento ocasionou maior desenvolvimento das brotações. O inicio da formação da conexão vascular entre o explante e o porta-enxerto foi observada aos 15 dias e estava estabelecida aos 30 dias. A indexação realizada pelo teste ELISA (Enzyme Linked Imunosorbent Assay) indireto aos 80 a 100 dias da microenxertia mostrou que 93 % das plantas testadas não apresentavam vírus detectável. __________________________________________________________________________________________ ABSTRACTThe sour passion fruit plant (Passiflora edulis Sims f. flavicarpa Deg.) is one of the most important Brazilian fruitbearings and its cultivation presents good perspectives of expansion. The culture development has been made more difficult by diseases, specially the fruit hardening disease, caused by the Cowpea aphid-borne mosaic virus (CABMV). The virus elimination by tissue culture has been a viable alternative for many species and can contribute to the superior genotypes vegetative propagation. This work was performed with the objective of studying the in vitro organogenesis in yellow passion fruit plants infected with the Cowpea aphid-borne mosaic virus (CABMV) and assessing the effect of the culture medium used over the grafting spot in ex vitro micrografting aiming at eliminating the CABMV virus. In the organogenesis study five accessions were evaluated: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) and four sources of explants: cauline apex, Internodal Segment, nodal Segment and foliar fragment. It was used for induction the medium MS supplemented by 2 mg.L-1 6-benzylaminopurine (BAP). The nodal Segment presented the best cultivation performance while the worst results were obtained with the foliar fragment. The accessions presented similar behavior in relation to the percentage of organogenic explants and to the production of shoots. It was observed in histological cuts meristemoids in nodal and apex explants. In the work involving the virus elimination through ex vitro micrografting, stem apexes originated from MAR 2050 accession infected plants were micrografted in seedlings obtained through the germination of seeds and cultivation in commercial substract under laboratory conditions. Experiments were conducted with the micrografting performed on the hypocotyl and epicotyl. Five culture media were tested as adjuvant, applied at the grafting spot. The average rate of setting was 27.22 % when the micrografting was performed on the hypocotyl and 32.22 % when performed on the epicotyl. The micrografting performed on the hypocotyl showed no effects with the application of culture media or growth regulators. The micrografting performed on the epicotyl and the MS medium supplemented with 3% sucrose, 10 mg.L-1 thiamine; 1 mg.L-1 pyridoxine; 1 mg.L-1 nicotinic acid; 100 mg L-1 mio-inositol and 2 gL-1 Phytagel, (basic medium), in addition to 0.1 mg.L-1 3-indolbutiric acid (AIB) and 1 mg.L-1 6- benzylaminopurine (BAP) provided 53.3% setting in the micrografting and was superior to xviii the other treatments, excepting the basic medium treatment supplemented with 2 mg L-1 BAP. The same treatment provided larger shoots development. The beginning of the vascular connection formation between the participants was observed within 15 days and was established in 30 days. The indexation performed by the ELISA (Enzyme Linked Imunosorbent Assay) indirect test within 80 to 100 days of the micrografting showed that 93 % of the plants tested did not present detectable virus
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Técnicas de cultivo in vitro e microenxertia ex vitro visando a eliminação do Cowpea Aphid-Borne Mosaic virus em Maracujazeiro-Azedo
2006Co-Authors: Ribeiro, Leonardo MonteiroAbstract:Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, 2006.O maracujazeiro-azedo (Passiflora edulis Sims f. flavicarpa Deg.) é uma das principais frutíferas brasileiras e seu cultivo apresenta boas perspectivas de expansão. O desenvolvimento da cultura tem sido dificultado por doenças, especialmente a doença do endurecimento dos frutos, causada pelo Cowpea aphid-borne mosaic virus (CABMV). A eliminação de vírus pela cultura de tecidos tem sido uma alternativa viável para muitas espécies e pode contribuir para a propagação vegetativa de genótipos superiores. O presente trabalho foi realizado com o objetivo de estudar a organogênese in vitro em plantas de maracujazeiro amarelo infectadas com o Cowpea aphid-borne mosaic virus (CABMV) e avaliar o efeito de meios de cultura utilizados sobre o ponto da enxertia na microenxertia ex vitro visando a eliminação do vírus CABMV. No estudo da organogênese foram avaliados cinco acessos: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) e quatro fontes de explantes: ápice caulinar, Segmento Internodal, Segmento nodal e fragmento foliar. Foi utilizado para indução o meio MS suplementado por 2 mg.L-1 de 6-benzilaminopurina (BAP). O Segmento nodal apresentou melhor desempenho no cultivo enquanto os piores resultados foram obtidos com o fragmento foliar. Os acessos apresentaram comportamento semelhante em relação ao percentual de explantes organogênicos e à produção de brotos. Foram observados em cortes histológicos meristemóides em explantes de nó e ápice. No trabalho envolvendo a eliminação de vírus por microenxertia ex vitro, ápices caulinares provenientes de plantas do acesso MAR-2050 infectadas foram microenxertados em plântulas obtidas pela germinação de sementes e cultivadas em substrato comercial em condição de laboratório. Foram conduzidos experimentos com a microenxertia realizada no hipocótilo e no epicótilo e testados cinco meios de cultura como adjuvantes, aplicados no ponto da enxertia. O índice de pegamento médio foi de 27,22 % quando a microenxertia foi realizada no hipocótilo e 32,22 % quando realizada no epicótilo. Na microenxertia realizada no hipocótilo não houve efeito da aplicação de meios de cultura ou reguladores de crescimento. Na microenxertia realizada no epicótilo o meio MS suplementado com 3% de sacarose, 10 mg.L-1 de tiamina; 1 mg.L-1 de piridoxina; 1 mg.L-1 de ácido nicotínico; 100 mg L-1 de mio-inositol e 2 gL-1 de Phytagel, (meio básico), acrescido de 0,1 mg.L-1 de ácido 3-indolbutírico (AIB) e 1 mg.L-1 de 6-benzilaminopurina (BAP) proporcionou 53,3% de pegamento e foi superior aos demais tratamentos, com exceção do tratamento meio básico suplementado com 2 mg L-1 xvi de BAP. O mesmo tratamento ocasionou maior desenvolvimento das brotações. O inicio da formação da conexão vascular entre o explante e o porta-enxerto foi observada aos 15 dias e estava estabelecida aos 30 dias. A indexação realizada pelo teste ELISA (Enzyme Linked Imunosorbent Assay) indireto aos 80 a 100 dias da microenxertia mostrou que 93 % das plantas testadas não apresentavam vírus detectável. __________________________________________________________________________________________ ABSTRACTThe sour passion fruit plant (Passiflora edulis Sims f. flavicarpa Deg.) is one of the most important Brazilian fruitbearings and its cultivation presents good perspectives of expansion. The culture development has been made more difficult by diseases, specially the fruit hardening disease, caused by the Cowpea aphid-borne mosaic virus (CABMV). The virus elimination by tissue culture has been a viable alternative for many species and can contribute to the superior genotypes vegetative propagation. This work was performed with the objective of studying the in vitro organogenesis in yellow passion fruit plants infected with the Cowpea aphid-borne mosaic virus (CABMV) and assessing the effect of the culture medium used over the grafting spot in ex vitro micrografting aiming at eliminating the CABMV virus. In the organogenesis study five accessions were evaluated: MAR-2003, MAR-2021, MAR-2024, MAR-2048, Rubi Gigante (RG) and four sources of explants: cauline apex, Internodal Segment, nodal Segment and foliar fragment. It was used for induction the medium MS supplemented by 2 mg.L-1 6-benzylaminopurine (BAP). The nodal Segment presented the best cultivation performance while the worst results were obtained with the foliar fragment. The accessions presented similar behavior in relation to the percentage of organogenic explants and to the production of shoots. It was observed in histological cuts meristemoids in nodal and apex explants. In the work involving the virus elimination through ex vitro micrografting, stem apexes originated from MAR 2050 accession infected plants were micrografted in seedlings obtained through the germination of seeds and cultivation in commercial substract under laboratory conditions. Experiments were conducted with the micrografting performed on the hypocotyl and epicotyl. Five culture media were tested as adjuvant, applied at the grafting spot. The average rate of setting was 27.22 % when the micrografting was performed on the hypocotyl and 32.22 % when performed on the epicotyl. The micrografting performed on the hypocotyl showed no effects with the application of culture media or growth regulators. The micrografting performed on the epicotyl and the MS medium supplemented with 3% sucrose, 10 mg.L-1 thiamine; 1 mg.L-1 pyridoxine; 1 mg.L-1 nicotinic acid; 100 mg L-1 mio-inositol and 2 gL-1 Phytagel, (basic medium), in addition to 0.1 mg.L-1 3-indolbutiric acid (AIB) and 1 mg.L-1 6- benzylaminopurine (BAP) provided 53.3% setting in the micrografting and was superior to xviii the other treatments, excepting the basic medium treatment supplemented with 2 mg L-1 BAP. The same treatment provided larger shoots development. The beginning of the vascular connection formation between the participants was observed within 15 days and was established in 30 days. The indexation performed by the ELISA (Enzyme Linked Imunosorbent Assay) indirect test within 80 to 100 days of the micrografting showed that 93 % of the plants tested did not present detectable virus
M.m. Villapecellin-cid - One of the best experts on this subject based on the ideXlab platform.
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Internodal myelinated Segments: delay and RGC time-domain Green function model
IEEE transactions on bio-medical engineering, 2004Co-Authors: M.m. Villapecellin-cid, Francisco Medina, Laura M. RoaAbstract:The myelinated axon can be modeled by means of a distributed RGC circuit. The Green function of this model allows for a generic formulation of the Internodal Segment response to any kind of stimulus, and accounts for the delay of the action potential associated with this Segment. The RGC model accuracy is comparable to that of a more complex electromagnetic model, and predicted delay agrees with experimental measurements.
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Transverse magnetic waves in myelinated nerves
2001 Conference Proceedings of the 23rd Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1Co-Authors: M.m. Villapecellin-cid, Laura M. Roa, Javier Reina-tosinaAbstract:The structure of myelinated axons is quite similar to that of a high-loss coaxial cable. An electromagnetic analysis of TM waves shows that distributed effects cannot be neglected. The attenuation and phase constants are obtained as a function of frequency. Predicted finite wave delay in the Internodal Segment approaches measurements.
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Ranvier nodes impedance match with Internodal transmission lines of myelinated axons
Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), 1Co-Authors: M.m. Villapecellin-cid, L. Rao, Javier Reina-tosinaAbstract:Most myelinated axon models are not concerned with Internodal Segments delay. Distributed effects could be thought as the cause of these delays. In this paper we use a myelinated axon model which takes into account both the distributed nature of the Internodal Segment and the loading effect of Ranvier nodes. Impedance match of Ranvier nodes is researched. We provide a detailed frequency domain analysis of axon behavior within the context of our model. Results show that Ranvier nodes are roughly matched with Internodal Segments.
Steve Millam - One of the best experts on this subject based on the ideXlab platform.
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Somatic embryogenesis in Solanum tuberosum L.: a histological examination of key developmental stages
Plant Cell Reports, 2004Co-Authors: Sanjeev Kumar Sharma, Steve MillamAbstract:A potential novel method of producing high-quality potato ( Solanum tuberosum L.) nuclear seeds is through the process of somatic embryogenesis (SE). Somatic embryo formation has been successfully reported in many plant species, but in potato, reliable SE systems are still at the experimental stage. A key factor in the success of any SE system is the ability to discriminate SE-specific cellular structures from those emerging through an organogenic route. In the investigation reported here we attempted to discriminate the progression of specific stages of potato SE by histological means. Internodal Segment (INS) explants from 4- to 6-week-old cv. Desiree in vitro cultures were successively cultured on SE induction (for 2 weeks) and expression/regeneration media (for 3 weeks) with and without 2,4-dichlorophenoxyacetic acid (5 μ M ). Microscopic examination of histological slides prepared using INS explants at different stages revealed the presence of characteristic globular, heart and torpedo stages in the potato SE system along with other associated unique features such as protoderm development and discrete vascular connections. These results confirm the occurrence of potato SE as per the accepted definition of the term.
