Características fenotípicas de semillas de soya mexicana y su correlación con la inducción de brotes in vitro y con la susceptibilidad de infección por Agrobacterium

Background and Aims: Soybean regeneration and transformation are considered highly genotype-specific; however, little is known about desirable seed traits that could be useful indicators of their regeneration and transformation capacities. In the present study, eight commercially available Mexican soybean varieties, as well as the Jack genotype as a control, were phenotypically characterized to determine the seed traits that are important factors for their in vitro performance and susceptibility to Agrobacterium tumefaciens infection.Methods: Grain dimensions, seed weight, moisture, oil, protein, ash, carbohydrate content and macro and micro elements (Mg, K, Ca, P, Na, Mn, Fe, Cu and Zn) were measured and correlated with the corresponding direct shoot organogenesis capability and Agrobacterium infection susceptibility using the cotyledonary node as explant.Key results: Notably, the ash content was the only important factor that inversely correlated with the capacity for shoot organogenesis, whereas carbohydrate and phosphorus content were positively correlated with susceptibility to Agrobacterium infection. The best response in terms of multiple shoot formation and Agrobacterium transient transformation was observed with the soybean varieties Huasteca-100, Nainari and Suaqui-86, which have lower ash content and a higher carbohydrate and phosphorus content.Conclusions: In most reported studies, seed phenotypic traits have been overlooked as factors that influence their regeneration and transformation potential. In the present study, we present evidence of associations between some specific seed traits and regeneration and transient transformation of soybean.Antecedentes y Objetivos: La regeneración y transformación de soya son consideradas altamente genotipo-específicas; sin embargo, muy poco se sabe acerca de rasgos deseables de la semilla que pudieran ser indicadores útiles de sus capacidades de regeneración y transformación. En el presente estudio, ocho variedades de soya mexicanas comercialmente disponibles, así como el genotipo Jack como control, se caracterizaron fenotípicamente con el fin de determinar qué características de la semilla son factores importantes para su desempeño in vitro y su susceptibilidad de infección por Agrobacterium tumefaciens.Métodos: Se midieron las dimensiones del grano, el peso de semilla, contenido de humedad, aceite, proteína, cenizas, carbohidratos, así como el contenido de macro y microelementos (Mg, K, Ca, P, Na, Mn, Fe, Cu y Zn) y se correlacionaron con la correspondiente capacidad de organogénesis directa y susceptibilidad de infección por Agrobacterium, usando el nodo cotiledonario como explante.Resultados clave: Notablemente, el contenido de cenizas fue el único factor importante que se correlacionó inversamente con la capacidad de organogénesis, mientras que los contenidos de carbohidratos y fósforo se correlacionaron positivamente con la susceptibilidad de infección por Agrobacterium. La mejor respuesta en términos de formación de brotes múltiples y transformación transitoria con Agrobacterium se observó con las variedades de soya Huasteca-100, Nainari y Suaqui-86, las cuales tienen un menor contenido de cenizas y un mayor contenido de carbohidratos y fósforo.Conclusiones: En la gran mayoría de estudios reportados, se han pasado por alto los rasgos fenotípicos de las semillas como posibles factores que influyen en su potencial de regeneración y transformación. En el presente estudio, presentamos evidencia de asociaciones entre algunos rasgos específicos de las semillas con la regeneración y la transformación transitoria de soya

Geoarqueología y paleontología de los depósitos de Pleistoceno Superior del antiguo Arroyo Abroñigal (Cuenca de Manzanares, Madrid): el yacimiento de Puente de los Tres Ojos

La excavación arqueológica del yacimiento del Puente de los Tres Ojos, próximo a la calle Cerro Negro (Madrid), ha aportado nuevos datos para profundizar en el conocimiento de la ocupación humana y en la reconstrucción paleoambiental del valle del antiguo arroyo Abroñigal, cuyo curso fluvial funcionó como afluente del río Manzanares posiblemente desde antes del Pleistoceno Superior hasta la segunda mitad del siglo XX. En el presente artículo se incluyen los aspectos geomorfológicos y cronoestratigráficos de los niveles excavados, documentándose varias secuencias fluviales y aluviales de relleno de la margen derecha del fondo de valle del Abroñigal en su tramo inferior. Durante la excavación se registró un amplio conjunto lítico, formado en su mayoría por piezas recuperadas en niveles de arenas y gravas correspondientes a episodios fluviales de media energía, a las que hay que añadir un porcentaje menor localizado en niveles de limos arcillosos y arenas finas. La mayor parte del conjunto lítico responde a sistemas técnicos propios del Paleolítico Medio, aunque destaca la presencia testimonial de piezas del Paleolítico Superior, además de restos de fauna de mamíferos correspondientes al Pleistoceno Superior, todo ello en niveles datados por OSL entre 14.400 y 11.170 años BP aproximadament

Charge Catastrophe and Dielectric Breakdown During Exposure of Organic Thin Films to Low-Energy Electron Radiation

Quantum Matter and Optic

The Aspartate-Semialdehyde Dehydrogenase of Edwardsiella ictaluri and Its Use as Balanced-Lethal System in Fish Vaccinology

asdA mutants of Gram-negative bacteria have an obligate requirement for diaminopimelic acid (DAP), which is an essential constituent of the peptidoglycan layer of the cell wall of these organisms. In environments deprived of DAP, i.e., animal tissues, they will undergo lysis. Deletion of the asdA gene has previously been exploited to develop antibiotic-sensitive strains of live attenuated recombinant bacterial vaccines. Introduction of an Asd+ plasmid into a ΔasdA mutant makes the bacterial strain plasmid-dependent. This dependence on the Asd+ plasmid vector creates a balanced-lethal complementation between the bacterial strain and the recombinant plasmid. E. ictaluri is an enteric Gram-negative fish pathogen that causes enteric septicemia in catfish. Because E. ictaluri is a nasal/oral invasive intracellular pathogen, this bacterium is a candidate to develop a bath/oral live recombinant attenuated Edwardsiella vaccine (RAEV) for the catfish aquaculture industry. As a first step to develop an antibiotic-sensitive RAEV strain, we characterized and deleted the E. ictaluri asdA gene. E. ictaluri ΔasdA01 mutants exhibit an absolute requirement for DAP to grow. The asdA gene of E. ictaluri was complemented by the asdA gene from Salmonella. Several Asd+ expression vectors with different origins of replication were transformed into E. ictaluri ΔasdA01. Asd+ vectors were compatible with the pEI1 and pEI2 E. ictaluri native plasmids. The balanced-lethal system was satisfactorily evaluated in vivo. Recombinant GFP, PspA, and LcrV proteins were synthesized by E. ictaluri ΔasdA01 harboring Asd+ plasmids. Here we constructed a balanced-lethal system, which is the first step to develop an antibiotic-sensitive RAEV for the aquaculture industry

TETX: a novel nuclear selection marker for Chlamydomonas reinhardtii transformation

Abstract Background Transformation of microalgae to obtain recombinant proteins, lipids or metabolites of economic value is of growing interest due to low costs associated with culture growth and scaling up. At present there are only three stable nuclear selection markers for the transformation of Chlamydomonas reinhardtii, which is the most commonly transformed microalgae, specifically: the aminoglycoside phosphotransferaseses aph7and aphVIII and the phleomycin resistance ble gene. As several microalgae are resistant to some of the antibiotics associated with the mentioned resistance genes, we have developed another alternative, tetX, a NADP-requiring Oxidoreductase that hydroxylates tetracycline substrates. We provide evidence that tetX can be used to obtain nuclear transformants of Chlamydomonas reinhardtii. Results We obtained nuclear transformants harbouring the tetX gene under the control of beta 2 tubulin or HSP70ARBCS2 promoters at an efficiency of transformation of 3.28 and 6.18 colony forming units/μg DNA respectively. This is the first report of a eukaryotic cell transformed using tetracycline as a selectable marker. Conclusions We developed a protocol for the nuclear transformation of Chlamydomonas reinhardtii using tetX as a selectable marker that confers stable resistance to tetracycline up to 100\ua0μg/mL. We believe tetX can be used to transform Chlamydomonas reinhardtii chloroplasts, related microalgae and other aerobic organisms sensitive to any tetracycline antibiotic.Abstract Background Transformation of microalgae to obtain recombinant proteins, lipids or metabolites of economic value is of growing interest due to low costs associated with culture growth and scaling up. At present there are only three stable nuclear selection markers for the transformation of Chlamydomonas reinhardtii, which is the most commonly transformed microalgae, specifically: the aminoglycoside phosphotransferaseses aph7and aphVIII and the phleomycin resistance ble gene. As several microalgae are resistant to some of the antibiotics associated with the mentioned resistance genes, we have developed another alternative, tetX, a NADP-requiring Oxidoreductase that hydroxylates tetracycline substrates. We provide evidence that tetX can be used to obtain nuclear transformants of Chlamydomonas reinhardtii. Results We obtained nuclear transformants harbouring the tetX gene under the control of beta 2 tubulin or HSP70ARBCS2 promoters at an efficiency of transformation of 3.28 and 6.18 colony forming units/μg DNA respectively. This is the first report of a eukaryotic cell transformed using tetracycline as a selectable marker. Conclusions We developed a protocol for the nuclear transformation of Chlamydomonas reinhardtii using tetX as a selectable marker that confers stable resistance to tetracycline up to 100\ua0μg/mL. We believe tetX can be used to transform Chlamydomonas reinhardtii chloroplasts, related microalgae and other aerobic organisms sensitive to any tetracycline antibiotic.CONACYT Beca N° 20965

Phenotypic traits of Mexican soybean seeds and their correlation with in vitro shoot induction and susceptibility to Agrobacterium infection

Abstract: Background and Aims: Soybean regeneration and transformation are considered highly genotype-specific; however, little is known about desirable seed traits that could be useful indicators of their regeneration and transformation capacities. In the present study, eight commercially available Mexican soybean varieties, as well as the Jack genotype as a control, were phenotypically characterized to determine the seed traits that are important factors for their in vitro performance and susceptibility to Agrobacterium tumefaciens infection. Methods: Grain dimensions, seed weight, moisture, oil, protein, ash, carbohydrate content and macro and micro elements (Mg, K, Ca, P, Na, Mn, Fe, Cu and Zn) were measured and correlated with the corresponding direct shoot organogenesis capability and Agrobacterium infection susceptibility using the cotyledonary node as explant. Key results: Notably, the ash content was the only important factor that inversely correlated with the capacity for shoot organogenesis, whereas carbohydrate and phosphorus content were positively correlated with susceptibility to Agrobacterium infection. The best response in terms of multiple shoot formation and Agrobacterium transient transformation was observed with the soybean varieties Huasteca-100, Nainari and Suaqui-86, which have lower ash content and a higher carbohydrate and phosphorus content. Conclusions: In most reported studies, seed phenotypic traits have been overlooked as factors that influence their regeneration and transformation potential. In the present study, we present evidence of associations between some specific seed traits and regeneration and transient transformation of soybean.Resumen: Antecedentes y Objetivos: La regeneración y transformación de soya son consideradas altamente genotipo-específicas; sin embargo, muy poco se sabe acerca de rasgos deseables de la semilla que pudieran ser indicadores útiles de sus capacidades de regeneración y transformación. En el presente estudio, ocho variedades de soya mexicanas comercialmente disponibles, así como el genotipo Jack como control, se caracterizaron fenotípicamente con el fin de determinar qué características de la semilla son factores importantes para su desempeño in vitro y su susceptibilidad de infección por Agrobacterium tumefaciens. Métodos: Se midieron las dimensiones del grano, el peso de semilla, contenido de humedad, aceite, proteína, cenizas, carbohidratos, así como el contenido de macro y microelementos (Mg, K, Ca, P, Na, Mn, Fe, Cu y Zn) y se correlacionaron con la correspondiente capacidad de organogénesis directa y susceptibilidad de infección por Agrobacterium, usando el nodo cotiledonario como explante. Resultados clave: Notablemente, el contenido de cenizas fue el único factor importante que se correlacionó inversamente con la capacidad de organogénesis, mientras que los contenidos de carbohidratos y fósforo se correlacionaron positivamente con la susceptibilidad de infección por Agrobacterium. La mejor respuesta en términos de formación de brotes múltiples y transformación transitoria con Agrobacterium se observó con las variedades de soya Huasteca-100, Nainari y Suaqui-86, las cuales tienen un menor contenido de cenizas y un mayor contenido de carbohidratos y fósforo. Conclusiones: En la gran mayoría de estudios reportados, se han pasado por alto los rasgos fenotípicos de las semillas como posibles factores que influyen en su potencial de regeneración y transformación. En el presente estudio, presentamos evidencia de asociaciones entre algunos rasgos específicos de las semillas con la regeneración y la transformación transitoria de soya