We would like to thank Dr. Nicholas J. Ashbolt and Dr. G. Shay Fout for their review of the manuscript.

1. Preparación de Cristalería y alojamientos de los filtros <ol style="margin-left: 40px;"><li> A menos que se indique lo contrario, esterilizar todos los artículos de vidrio, soportes y soluciones de filtrado a 121 ° C durante 15 minutos. Para asegurar la esterilidad, cubrir todas las aberturas o las superficies expuestas, ya sea con papel de aluminio o papel cinta asegurado antes de la esterilización. </li><li> Montar aparato de filtración uniendo carcasa del filtro (47 mm de diámetro) a 1 L matraz Erlenmeyer de brazo lateral. Recoger filtros necesarios: filtros de disco electropositivos / electronegativo 47 mm de diámetro. </li><li> Preparar 1 L de extracto de carne 1,5% (floculación, produce partículas de flóculo cuando el pH de la solución se redujo a 3,5, o no floculante, lo que no hace agregada a pH 3,5), con 0,05 M de glicina, disolviendo 15 g de extracto de carne de vacuno en 1 L de agua desionizada y la adición de 3,75 g de glicina. NOTA: extractos de carne no floculantes requerirán la adición de celita antes de la concentración terciaria. </li><li> Añadir elución polyph sodio aditivoosphate al extracto de carne de vacuno en una concentración de 0,1%. </li><li> Añadir una solución de ácido clorhídrico 1 M, gota a gota, a la mezcla de extracto de carne, solución de pH a pH deseado. Extracto de carne Autoclave durante 15-30 minutos a 121 ° C. </li><li> Mide 0,1 g de fino, medio, o celita partícula grande (para usar con sólo el extracto de carne no floculantes). </li><li> Preparar vacío / aspiración uniendo tubos compatible con erlenmeyer brazo lateral ya la toma de vacío. </li></ol> 2. Preparación de Soluciones y virus Stock <ol style="margin-left: 40px;"><li> Preparar 1 L de HCl 1 M. </li><li> Preparar 1 l de 1 M NaOH. </li><li> Prepare la solución de PBS 1x (NaCl 137 mM, KCl 2,7 mM, 1,47 mM K 2 PO 4 y 4,3 mM NaH 2 PO 4). <ol><li> Ajustar el pH de 1x PBS a 9,0 utilizando 1 M NaOH. </li></ol></li><li> Preparar y diluir de virus a 10 4 -10 5 número más probable (NMP) ml -1 mezclando 1 ml de virus de reserva con 9 ml de PBS (pH7), como se describió previamente 8,13. Conservar a -80 ° C en alícuotas de 1 ml. <ol><li> Esterilizar virus de stock de filtrado jeringa (0,22 m de tamaño de poro) para eliminar los contaminantes potenciales. </li></ol></li><li> Sin cloro del agua corriente <ol><li> Medida 1 L de agua del grifo estéril usando un cilindro graduado estéril y verter en un vaso de precipitados de 2 l que contenía una barra de agitación magnética. </li><li> Añadir 0,7 g de tiosulfato de sodio y mezclar hasta que se disuelven los gránulos. Ajustar el pH del agua del grifo para 7-7,5 si es necesario el uso de HCl 1 M o solución de NaOH 1M. </li><li> Pico virus Deshielo (1 ml) y se añade todo el volumen de pico a 1 l de agua del grifo estéril sin cloro. Mezclar durante 10 min. </li><li> Preparar un blanco método (el agua del grifo sin cloro y sin adenovirus) con cada experimento y el proceso de la misma manera que la muestra de púas. </li></ol></li></ol> 3. Preparación de Millipore Filtro Aparato <ol style="margin-left: 40px;"><li> Retirar la cobertura estéril sobre la carcasa del filtro. Asegurarajuste adecuado entre la carcasa del filtro tazón superior y pantalla de filtro inferior para evitar fugas de la muestra durante la filtración. </li><li> Retirar la cobertura estéril de 1 frasco L Erlenmeyer. Asegúrese de que el corcho de la unidad de filtro se ajusta perfectamente en la abertura superior de erlenmeyer, creando un buen sello. </li><li> Retire el tazón superior de la unidad de filtro de malla del filtro inferior y colocar 47 mm disco de filtro electropositivo de lleno sobre la pantalla con pinzas estériles. Adjuntar filtro tazón vivienda a la pantalla inferior y ajustar en su lugar girando en sentido antihorario. </li></ol> 4. Pulse de filtración de agua (Concentración Primaria) <ol style="margin-left: 40px;"><li> Medir 100 ml de virus se dispararon el agua del grifo usando estéril probeta. </li><li> Vierta 100 ml de virus se dispararon el agua del grifo en la carcasa del filtro que contiene o bien un filtro de 47 mm de vidrio plisado / celulosa o un filtro de disco de fibra nano-alúmina / vidrio. </li><li> Deje que el agua pase lentamente a través del filtro. Aplicar vacío suave para eliminar los residuos restantes oagua del grifo f de la superficie del filtro. </li><li> Si se utiliza el tratamiento con tripsina, añadir 5 ml de tripsina al 0,25% para filtrar superficie e incubar durante 5 minutos. </li><li> Lavar la tripsina de la superficie del filtro utilizando 50 ml de agua desionizada estéril. </li></ol> 5. La elución Virus del filtro <ol style="margin-left: 40px;"><li> Retire la carcasa del filtro de 2 L frasco Erlenmeyer, y el lugar en frasco de 250 ml brazo lateral. </li><li> Medir 100 ml de extracto de carne utilizando cilindro graduado. Vierta lentamente 100 ml de extracto de carne en caja del filtro. </li><li> Permitir extracto de carne para verter a través del filtro, capturando extracto de carne en una pequeña (250 ml) matraz Erlenmeyer. Aplicar vacío para tirar a través de extracto de carne residual del filtro. </li></ol> 6. Celite Concentración Secundaria <ol style="margin-left: 40px;"><li> Frascos de transferencia que contiene los virus eluidas a una placa de agitación. Añadir estéril barra de agitación magnética y colocar en placa de agitación, mezcla para crear ligero vórtice. </li><li> Añadir 0,1 g de celitepolvo a 100 ml de extracto de carne y permitir de celite para dispersar. Coloque la sonda de pH estéril en extracto de carne. </li><li> Añadir gota a gota HCl 1 M de extracto de carne para alcanzar un pH de 4,0. Permita mezclar lentamente durante 10 min. </li><li> Coloque 47 mm pre-filtro en la carcasa del filtro (como se describió anteriormente) usando un matraz Erlenmeyer de 2 l. </li><li> Verter 100 ml de extracto de carne de vacuno / de la mezcla de celite sobre pre-filtro. Permita que el extracto de carne vierta a través. Aplicar ligero vacío para salir adelante extracto de carne residual del filtro. </li><li> Coloque el metal clip de tubo en el extremo del tubo de salida del filtro. Adjuntar estéril 15 ml tubo de recogida de polipropileno para clip de tubo de metal. Coloque la carcasa del filtro de nuevo en erlenmeyer. </li><li> Añadir 5 ml de tampón 1x PBS, pH 9,0 sobre celite recogida en pre-filtro. </li><li> Permita PBS gotee a través de pre-filtro. Aplicar ligero vacío para salir adelante PBS residual en 15 ml tubo de recogida. </li></ol> 7. Orgánica floculación Concentración Secundaria <ol style="margin-left: 40px;"><li>La transferencia de los vasos que contienen el virus se eluyó a una placa de agitación. Añadir una barra de agitación magnética estéril a 100 ml de extracto de carne y mezclar para crear ligero vórtice. </li><li> Coloque la sonda de pH estéril en extracto de carne. </li><li> Añadir 1 M de HCl gota a gota a extracto de carne y ajustar el pH a 3,5. Mezclar durante 30 min. </li><li> Verter el eluato en 250 ml tubos cónicos de centrífuga y centrifugar a 2500 xg durante 15 min a 4 ºC. </li><li> Verter el sobrenadante con cuidado de no de no perturbar el sedimento. Resuspender el precipitado en 5 ml de 1x PBS, pH 9. </li><li> Centrifugar la suspensión a 4.000 xg durante 10 min a 4 ºC. Verter el sobrenadante y desechar el sedimento. </li><li> Ajustar el pH a 7-7,5, esterilizar por filtración a través de filtro de jeringa de 0,22 micras y congelación a -80 ° C. </li></ol> 8. Viral Nucleic Acid Extracción <ol style="margin-left: 40px;"><li> Extraer ácidos nucleicos virales utilizando un kit comercial apropiado de acuerdo con las instrucciones del fabricante. </li></ol> &lt;p class = &quot;jove_title&quot;&gt; 9. AdV 40/41 qPCR <ol style="margin-left: 40px;"><li> Utilice cebadores y sondas, así como la mezcla de reacción y perfiles de ciclo térmico según lo publicado 8,13. NOTA: límite estimado de detección del ensayo es de aproximadamente 5 unidades qPCR por reacción. </li><li> Añadir componentes de las mezclas de amplificación de PCR en concentraciones como sigue: Tris 10 mM (pH 8,3), KCl 50 mM, 4,5 mM de MgCl 2, mM dNTPs 10, 10 mM cebadores y sonda 1 M y 0,5 l de polimerasa de manera que los volúmenes finales de 45 l se puede añadir al número apropiado de pozos dentro de una placa de 96 pocillos de reacción PCR. </li><li> Cargar 45 l de mezcla de amplificación PCR a cada pocillo apropiado de una de 96 pocillos, la placa de PCR reacción rápida. </li><li> Añadir 5 l de ADN extraído de la muestra a los pocillos apropiados de la placa de PCR. </li><li> Cubra la placa con junta de la tapa resistente al calor, girar la placa para mover cualquier gota a fondo de pozos de la placa de PCR. </li><li> Establecer ciclos de amplificación por PCR como follOWS: 95 ° C durante 10 min, seguido por 40 ciclos de 95 ° C durante 15 segundos y 60 ° C durante 1 min. </li></ol> 10. Análisis de datos <ol style="margin-left: 40px;"><li> Analizar mediciones por triplicado de las diluciones en serie de 5 veces de las muestras que abarcan 1: 5 a 1: 625 dilución gama con el fin de determinar el número más probable (MPN) de las partículas virales, como se describió previamente 8,13. </li><li> Analizar diluciones en serie de 5 veces de los picos experimentales de adenovirus que abarcan 1: 5 a 1: 15.625 rango de dilución para determinar el número más probable (MPN) de las partículas virales. </li><li> El uso de la calculadora EPA MPN (http://www.epa.gov/nerlcwww/online.html), ajustar la calculadora para tener en cuenta el tipo de dilución (1: 5 ó 1:10), el número de diluciones realizado, y el número de replicar muestras en serie de dilución. </li><li> Realizar log 10 transformación de los datos, seguido por la normalización a una unidad de volumen (por ejemplo, 1 ml, 100 ml, etc. </em&gt;). Calcular recuperaciones para experimento dado dividiendo la cantidad de partículas virales presentes en la muestra se concentra con el número de partículas virales presentes en los picos experimentales. </li><li> Evaluar el efecto de las diferentes variables experimentales (por ejemplo, diferentes tipos de celite, se rangos de pH, diferentes tipos de filtros y diferentes técnicas de concentración secundarios) sobre recuperaciones AdV mediante la realización de pruebas estadísticas paramétricas o no paramétricas (por ejemplo, prueba t pareada, uno o dos -Way ANOVA) dependiendo de la distribución de los datos y el diseño experimental. </li></ol>

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No competing financial interests. 
The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

Filtros electropositivos son útiles en la concentración de virus del agua; sin embargo, estos filtros pueden diferir en su estructura y composición, que a su vez podría alterar su eficacia. Para agravar este problema, las estructuras de la cápside y cargos varían entre las cepas de virus que requieren ser adaptados técnicas de concentración para asegurar una recuperación óptima 15. A través de simples modificaciones de las técnicas de concentración existentes (por ejemplo, los filtros el...

Virus entéricos humanos son agentes causantes importantes de enfermedades de origen hídrico 1-3, pero generalmente están presentes en números bajos en aguas ambientales contaminadas, por lo que su detección difícil sin concentración. Los procedimientos utilizados para concentrar virus incluyen típicamente una etapa de filtración, seguido de elución de filtro, y la concentración secundaria del eluato filtro. Un procedimiento de filtración común se basa en la utilización de membranas cargadas tales como filtros electropositivos (recientemente revisado en 4,5). Estos filtros se basan en la captura de los virus en suspensión en el agua utilizando interacciones electrostáticas entre la superficie del filtro (con carga positiva) y partículas de virus específicos (con carga negativa). Dos filtros electropositivos que están disponibles comercialmente se basan en esta tecnología, los filtros de vidrio / celulosa y fibra nano-alúmina / vidrio. Los costes de filtro de vidrio / celulosa son hasta 10 veces mayor que la de la fibra nano-alúmina / vidrio, que limitan el uso del vidrio / cefiltros llulose para la vigilancia del virus de rutina. Estudios recientes han concluido diferencias son nominales entre estos dos filtros en la recuperación de los enterovirus desde 6,7 del agua ambiente, lo que justifica el uso de una alternativa de filtro más barato. Otras opciones de filtro, como los filtros electronegativos y de lana de vidrio se han estudiado, sin embargo, o bien requieren el tratamiento previo de las fuentes de agua (filtros electronegativos) o no están disponibles en el mercado (filtros de lana de vidrio). El desarrollo de procedimientos de concentración de virus se ha centrado principalmente en la optimización de las técnicas de concentración primaria (filtros) con el fin de mejorar la recuperación de virus de agua. Sin embargo, los procedimientos de concentración secundarios, que reducen el volumen de eluyente típicamente de 1 L a mililitro volúmenes, también pueden tener un impacto significativo en las recuperaciones de virus 8. Concentración secundaria de virus entéricos típicamente se basa en un agente floculante, tales como algunos tipos de extracto de carne (floccu orgánicamento) o floculación de la leche desnatada 9-12 para eliminar las partículas de virus de las superficies del filtro. Recientemente, otro procedimiento de concentración secundaria utilizando extracto de carne junto con la adición de celita (partículas finas) ha mostrado ser prometedor para la recuperación de adenovirus, enterovirus y norovirus 8,13,14. Obras de concentración Celite bajo principios similares a la del método de floculación orgánica en que las partículas de virus se unen a y se liberan de partículas (floc o de celite) alterando el pH de la solución en suspensión. Las comparaciones entre estas dos técnicas de concentración secundarias han sido evaluadas en la recuperación de adenovirus (ADV) de pinchos tipos 40 y 41 8. Este estudio concluyó que las dos técnicas de concentración secundarias fueron estadísticamente similares en la recuperación de adenovirus. Sin embargo, el método de floculación orgánica requiere una 30 min. de incubación a pH 3,5, mientras que la técnica de celite requiere una incubación más corto (10 min) a pH 4,0. El flocculat orgánicaion también requiere el uso de equipo de laboratorio caro (centrifugadoras) para recoger las partículas de flóculos durante la concentración terciaria, la técnica de celite en contraste utiliza sólo el equipo de laboratorio básico (filtración a vacío) para separar partículas de Celite de la suspensión. Ciertas combinaciones de filtros y técnicas de elución secundarias también pueden afectar a las recuperaciones de virus. Un estudio concluyó que ciertas combinaciones de (filtros electropositivos) primarias y secundarias técnicas de concentración (Celite o floculación orgánica) tuvieron un impacto significativo de la recuperación del adenovirus 13. Estos hallazgos sugieren que se requiere la optimización a fin de recuperar de manera óptima virus diana a partir de una matriz de agua dado al utilizar estas técnicas. La optimización es una pérdida de tiempo y arduo proceso de muchos investigadores evitan activamente desde numerosas variables serán evaluados (tipo de filtro / marca, solución de elución de pH, celita / floculación orgánica). Para este study, se desarrolló un procedimiento para identificar las condiciones óptimas para la concentración de virus a partir de agua usando cepas de adenovirus humano de púas 40 y 41. Presumiblemente, ya que cada tipo virus muestra una morfología de la cápside único y carga específica de la cápside, pueden necesitar ser optimizado para cada virus protocolos de concentración apuntar a fin de alcanzar la recuperación viral óptima. Este estudio proporciona un enfoque para AdV 40 y 41 de concentración por: 1) la evaluación de la recuperación de virus en el agua del grifo, usando discos de filtro electropositivos seguido por 2) evaluación de un método de floculación orgánica establecido frente a la técnica de celite como una concentración secundaria, y 3) evaluación de tampones de elución para la concentración terciaria.

<table border="0" cellpadding="0" cellspacing="0" width="786">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Name of Reagent/ Equipment</td>
			<td style="width:143px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td style="width:295px;">Comments/Description</td>
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			<td height="21" style="height:21px;width:231px;">Adenovirus 40 stock</td>
			<td style="width:143px;">ATCC</td>
			<td style="width:119px;">VR-931</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Adenovirus 41 stock</td>
			<td style="width:143px;">ATCC</td>
			<td style="width:119px;">VR-930</td>
			<td></td>
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		<tr height="21">
			<td height="21" style="height:21px;width:231px;">Sodium Thiosulfate</td>
			<td style="width:143px;">Fluka Chemical Co.</td>
			<td style="width:119px;">72051</td>
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			<td height="21" style="height:21px;width:231px;">Celites #577</td>
			<td style="width:143px;">Fluka Chemical Co.</td>
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			<td height="21" style="height:21px;width:231px;">NanoCeram 47mm</td>
			<td style="width:143px;">Argonide</td>
			<td style="width:119px;">N/A</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:231px;">1MDS 47mm</td>
			<td style="width:143px;">3M</td>
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			<td></td>
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			<td height="21" style="height:21px;width:231px;">AP-20 Prefilter 47mm</td>
			<td style="width:143px;">Millipore Corp.</td>
			<td style="width:119px;">AP2004700</td>
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			<td height="21" style="height:21px;width:231px;">Glycine&#160;</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">50046-1KG</td>
			<td></td>
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			<td height="21" style="height:21px;width:231px;">Sodium Polyphosphate</td>
			<td style="width:143px;">Acros Organics</td>
			<td style="width:119px;">390930010</td>
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			<td height="21" style="height:21px;width:231px;">Trypsin</td>
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			<td height="21" style="height:21px;width:231px;">PBS</td>
			<td style="width:143px;">Sigma</td>
			<td style="width:119px;">P5368</td>
			<td></td>
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			<td height="21" style="height:21px;width:231px;">Hydrochloric Acid</td>
			<td style="width:143px;">Fisher</td>
			<td style="width:119px;">A481-212</td>
			<td></td>
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			<td height="21" style="height:21px;width:231px;">BBL Beef Extract</td>
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			<td style="width:119px;">212303</td>
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			<td height="21" style="height:21px;width:231px;">Difco Beef Extract</td>
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			<td height="25" style="height:25px;width:231px;">ABI 7900 Real-time PCR system</td>
			<td style="width:143px;">ABI</td>
			<td style="width:119px;">N/A</td>
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			<td height="21" style="height:21px;width:231px;">Stainless Steel Filter Housing</td>
			<td style="width:143px;">Millipore Corp.</td>
			<td>XX2004720</td>
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			<td height="21" style="height:21px;width:231px;">Blood DNA Extraction Kit</td>
			<td style="width:143px;">Qiagen&#160;</td>
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			<td height="21" style="height:21px;width:231px;">EPA MPN Calculator</td>
			<td style="width:143px;"></td>
			<td style="width:119px;"></td>
			<td>http://www.epa.gov/nerlcwww/online.html</td>
		</tr>
	</tbody>
</table>

a small volume procedure for viral concentration from water

Small-scale concentration of viruses (sample volumes 1-10 L, here simulated with spiked 100 ml water samples) is an efficient, cost-effective way to identify optimal parameters for virus concentration. Viruses can be concentrated from water using filtration (electropositive, electronegative, glass wool or size exclusion), followed by secondary concentration with beef extract to release viruses from filter surfaces, and finally tertiary concentration resulting in a 5-30 ml volume virus concentrate. In order to identify optimal concentration procedures, two different electropositive filters were evaluated (a glass/cellulose filter [1MDS] and a nano-alumina/glass filter [NanoCeram]), as well as different secondary concentration techniques; the celite technique where three different celite particle sizes were evaluated (fine, medium and large) followed by comparing this technique with that of the established organic flocculation method. Various elution additives were also evaluated for their ability to enhance the release of adenovirus (AdV) particles from filter surfaces. Fine particle celite recovered similar levels of AdV40 and 41 to that of the established organic flocculation method when viral spikes were added during secondary concentration. The glass/cellulose filter recovered higher levels of both, AdV40 and 41, compared to that of a nano-alumina/glass fiber filter. Although not statistically significant, the addition of 0.1% sodium polyphosphate amended beef extract eluant recovered 10% more AdV particles compared to unamended beef extract.

<html> Selección de Celite Tres tipos diferentes de celita fueron probados antes de la selección de la mejor variante de realización. Celites con bien a las partículas de tamaño mediano producen los más altos recuperaciones de adenovirus. El uso de celites más grandes resultó en menores recuperaciones tanto para AdV40 y 41 (rango de 32% -100%) (Figura 1). Promedio de recuperaciones de adenovirus 40 eran 144% ± 52% (muy bien), 115% ± 28% (medio) y 82% ± 53% celites ...

Watch this Scientific Journal Video about A Small Volume Procedure for Viral Concentration from Water at JoVE.com

A Small Volume Procedure for Viral Concentration from Water

An approach was developed for identifying optimal viral concentration conditions for small volume water samples using spikes of human adenovirus. The techniques described here are used to identify concentration parameters for other viral targets, and applied to large-scale viral concentration experimentation.

Un procedimiento de volumen pequeño para la concentración viral del Agua

Small-scale concentration of viruses (sample volumes 1-10 L, here simulated with spiked 100 ml water samples) is an efficient, cost-effective way to ...

a-small-volume-procedure-for-viral-concentration-from-water

Research

JoVE Journal

Environment

10.0K vistas.  U.S. EPA. An approach was developed for identifying optimal viral concentration conditions for small volume water samples using spikes of human adenovirus. The techniques described here are used to identify concentration parameters for other viral targets, and applied to large-scale viral concentration experimentation. 

Video: A Small Volume Procedure for Viral Concentration from Water

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration.
Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release.
The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations.

Lake eutrophication is a water quality issue worldwide, making the need to identify and control nutrient sources critical. Laboratory determination of phosphorus release rates from sediment cores is a valuable approach for determining the role of internal phosphorus loading and guiding management decisions.

Laboratorio-determinado Fósforo Flujo de sedimentos lacustres como medida de fósforo Interna Loading

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) ...

Investigación

Medio ambiente

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated (WATER-PAM) Fluorometry

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be subsampled throughout the experiment1&#8211;7. Subsampling of large volumes can be problematic for several reasons: 1) it causes variation in the total volume and the surface area:volume ratio of the culture during the experiment; 2) pseudo-replication (i.e., replicate samples from the same treatment flask8) is often employed rather than true replicates (i.e., sampling from replicate treatments); 3) the duration of the experiment is limited by the total volume; and 4) axenic cultures or the usual bacterial microbiota are difficult to maintain during long-term experiments as contamination commonly occurs during subsampling.
The use of microtiter plates enables 1 ml culture volumes to be used for each replicate, with up to 48 separate treatments within a 12.65 x 8.5 x 2.2 cm plate, thereby decreasing the experimental volume and allowing for extensive replication without subsampling any treatment. Additionally, this technique can be modified to fit a variety of experimental formats including: bacterial-algal co-cultures, algal physiology tests, and toxin screening9&#8211;11. Individual wells with an alga, bacterium and/or co-cultures can be sampled for numerous laboratory procedures including, but not limited to: WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry, microscopy, bacterial colony forming unit (cfu) counts and flow cytometry. The combination of the microtiter plate format and WATER-PAM fluorometry allows for multiple rapid measurements of photochemical yield and other photochemical parameters with low variability between samples, high reproducibility and avoids the many pitfalls of subsampling a carboy or conical flask over the course of an experiment.

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated WATER-PAM Fluorometry

The goal of this procedure is to demonstrate the reproducibility and adaptability of using a microtiter plate format for microalgal screening. This rapid screen combines WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry to measure photosynthetic yield as an indicator of Photosystem II (PSII) health with small volume bacterial-algal co-cultures.

Un ensayo biológico Volumen pequeños para evaluar bacteriana / fitoplancton Co-cultura Usando AGUA-Pulse-Amplitud Modulada (AGUA-PAM) Fluorometría

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be ...

A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function

Continuing increases in atmospheric carbon dioxide concentrations (CA) mandate techniques for examining impacts on terrestrial ecosystems. Most experiments examine only two or a few levels of CA concentration and a single soil type, but if CA can be varied as a gradient from subambient to superambient concentrations on multiple soils, we can discern whether past ecosystem responses may continue linearly in the future and whether responses may vary across the landscape. The Lysimeter Carbon Dioxide Gradient Facility applies a 250 to 500 &#181;l L-1 CA gradient to Blackland prairie plant communities established on lysimeters containing clay, silty clay, and sandy soils. The gradient is created as photosynthesis by vegetation enclosed in in temperature-controlled chambers progressively depletes carbon dioxide from air flowing directionally through the chambers. Maintaining proper air flow rate, adequate photosynthetic capacity, and temperature control are critical to overcome the main limitations of the system, which are declining photosynthetic rates and increased water stress during summer. The facility is an economical alternative to other techniques of CA enrichment, successfully discerns the shape of ecosystem responses to subambient to superambient CA enrichment, and can be adapted to test for interactions of carbon dioxide with other greenhouse gases such as methane or ozone.

A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function

The Lysimeter Carbon Dioxide Gradient Facility creates a 250 to 500 &#181;l L-1 linear carbon dioxide gradient in temperature-controlled chambers housing grassland plant communities on clay, silty clay, and sandy soil monoliths. The facility is used to determine how past and future carbon dioxide levels affect grassland carbon cycling.

A CO<sub&gt; 2</sub&gt; Fondo gradiente de concentración para las pruebas de CO<sub&gt; 2</sub&gt; Enriquecimiento y suelo Efectos sobre la Función de los Ecosistemas del Prado

Continuing increases in atmospheric carbon dioxide concentrations (CA) mandate techniques for examining impacts on terrestrial ecosystems. Most ...

A Simple Method for Automated Solid Phase Extraction of Water Samples for Immunological Analysis of Small Pollutants

A new method for solid phase extraction (SPE) of environmental water samples is proposed. The developed prototype is cost-efficient and user friendly, and enables to perform rapid, automated and simple SPE. The pre-concentrated solution is compatible with analysis by immunoassay, with a low organic solvent content. A method is described for the extraction and pre-concentration of natural hormone 17&#946;-estradiol in 100 ml water samples. Reverse phase SPE is performed with octadecyl-silica sorbent and elution is done with 200 &#181;l of methanol 50% v/v. Eluent is diluted by adding di-water to lower the amount of methanol. After preparing manually the SPE column, the overall procedure is performed automatically within 1 hr. At the end of the process, estradiol concentration is measured by using a commercial enzyme-linked immune-sorbent assay (ELISA). 100-fold pre-concentration is achieved and the methanol content in only 10% v/v. Full recoveries of the molecule are achieved with 1 ng/L spiked de-ionized and synthetic sea water samples.

A protocol for the extraction and pre-concentration of estradiol from water samples by using an automated and miniaturized system is presented.

Un método simple para la fase sólida automatizada Extracción de muestras de agua para análisis inmunológico de los pequeños contaminantes

A new method for solid phase extraction (SPE) of environmental water samples is proposed. The developed prototype is cost-efficient and user friendly, and ...

Extracting Metrics for Three-dimensional Root Systems: Volume and Surface Analysis from In-soil X-ray Computed Tomography Data

Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as processes with important implications to climate change and crop management. Quantitative size information on roots in their native environment is invaluable for studying root growth and environmental processes involving plants. X-ray computed tomography (XCT) has been demonstrated to be an effective tool for in situ root scanning and analysis. We aimed to develop a costless and efficient tool that approximates the surface and volume of the root regardless of its shape from three-dimensional (3D) tomography data. The root structure of a Prairie dropseed (Sporobolus heterolepis) specimen was imaged using XCT. The root was reconstructed, and the primary root structure was extracted from the data using a combination of licensed and open-source software. An isosurface polygonal mesh was then created for ease of analysis. We have developed the standalone application imeshJ, generated in MATLAB1, to calculate root volume and surface area from the mesh. The outputs of imeshJ are surface area (in mm2) and the volume (in mm3). The process, utilizing a unique combination of tools from imaging to quantitative root analysis, is described. A combination of XCT and open-source software proved to be a powerful combination to noninvasively image plant root samples, segment root data, and extract quantitative information from the 3D data. This methodology of processing 3D data should be applicable to other material/sample systems where there is connectivity between components of similar X-ray attenuation and difficulties arise with segmentation.

A methodology for obtaining visual and quantitative root structure information from X-ray computed tomography data acquired in-soil is presented.

La extracción de las métricas para los sistemas de raíces de tres dimensiones: volumen y de superficie Análisis de In-suelo de rayos X de tomografía computarizada de datos

Plant roots play a critical role in plant-soil-microbe interactions that occur in the rhizosphere, as well as processes with important implications to ...

Soil Lysimeter Excavation for Coupled Hydrological, Geochemical, and Microbiological Investigations

Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative in improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. We present an experimental method, designed to capture sub-surface heterogeneity of an initially homogeneous soil system. This method is based on destructive sampling of a soil lysimeter designed to simulate a small-scale hillslope. A weighing lysimeter of one cubic meter capacity was divided into sections (voxels) and was excavated layer-by-layer, with sub samples being collected from each voxel. The excavation procedure was aimed at detecting the incipient heterogeneity of the system by focusing on the spatial assessment of hydrological, geochemical, and microbiological properties of the soil. Representative results of a few physicochemical variables tested show the development of heterogeneity. Additional work to test interactions between hydrological, geochemical, and microbiological signatures is planned to interpret the observed patterns. Our study also demonstrates the possibility of carrying out similar excavations in order to observe and quantify different aspects of soil-development under varying environmental conditions and scale.

This study presents an excavation method for investigating subsurface hydrological, geochemical, and microbiological heterogeneity of a soil lysimeter. The lysimeter simulates an artificial hillslope which was initially under homogeneous condition and had been subjected to approximately 5,000 mm of water over eight cycles of irrigation in an 18-month period.

Lisímetro suelo de excavación para acoplados hidrológicos, geoquímicos, e investigaciones microbiológicas

Studying co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled ...

Extraction of Organochlorine Pesticides from Plastic Pellets and Plastic Type Analysis

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment during manufacturing and transport. Because of their environmental persistence, they are widely distributed in the oceans and on beaches all over the world. They can act as a vector of potentially toxic organic compounds (e.g., polychlorinated biphenyls) and might consequently negatively affect marine organisms. Their possible impacts along the food chain are not yet well understood. In order to assess the hazards associated with the occurrence of plastic pellets in the marine environment, it is necessary to develop methodologies that allow for rapid determination of associated organic contaminant levels. The present protocol describes the different steps required for sampling resin pellets, analyzing adsorbed organochlorine pesticides (OCPs) and identifying the plastic type. The focus is on the extraction of OCPs from plastic pellets by means of a pressurized fluid extractor (PFE) and on the polymer chemical analysis applying Fourier Transform-InfraRed (FT-IR) spectroscopy. The developed methodology focuses on 11 OCPs and related compounds, including dichlorodiphenyltrichloroethane (DDT) and its two main metabolites, lindane and two production isomers, as well as the two biologically active isomers of technical endosulfan. This protocol constitutes a simple and rapid alternative to existing methodology for evaluating the concentration of organic contaminants adsorbed on plastic pieces.

Microplastics act as vector of potentially toxic organic contaminants with unpredictable effects. This protocol describes an alternative methodology for assessing the levels of organochlorine pesticides adsorbed on plastic pellets and identifying the polymer chemical structure. The focus is on pressurized fluid extraction and attenuated total reflectance Fourier transform infrared spectroscopy.

Extracción de plaguicidas organoclorados de pellets de plástico y análisis de tipos de plástico

Plastic resin pellets, categorized as microplastics (&#8804;5 mm in diameter), are small granules that can be unintentionally released to the environment ...

Capturing Flow-weighted Water and Suspended Particulates from Agricultural Canals During Drainage Events

The purpose of this study is to describe the methods used to capture flow-weighted water and suspended particulates from farm canals during drainage discharge events. Farm canals can be enriched by nutrients such as phosphorus (P) that are susceptible to transport. Phosphorus in the form of suspended particulates can significantly contribute to the overall P loads in drainage water. A settling tank experiment was conducted to capture suspended particulates during discrete drainage events. Farm canal discharge water was collected in a series of two 200 L settling tanks over the entire duration of the drainage event, so as to represent a composite subsample of the water being discharged. Imhoff settling cones are ultimately used to settle out the suspended particulates. This is achieved by siphoning water from the settling tanks via the cones. The particulates are then collected for physico-chemical analyses.

Nutrients present in particulate form can contribute significantly to the overall loads in agricultural drainage waters. This study describes a novel method to capture flow-weighted water and suspended particulates from farm canal drainage over the entire duration of the drainage event.

Captura de agua cargada de flujo y las partículas en suspensión de canales agrícolas durante los eventos de drenaje

The purpose of this study is to describe the methods used to capture flow-weighted water and suspended particulates from farm canals during drainage ...

A Simple Planting Technique for Re-establishing Trees Where Frequent Inundation Occurs

Many of the Everglades tree islands have lost elevation over the past century and most of their trees have died such that they are now covered with herbaceous plants. This protocol describes a simple, cost-effective tree planting technique needed for restoring degraded Everglade tree islands. The design is patterned after a natural Everglades process that creates floating peat islands, which allows tree survival and growth in flooded conditions and often leads to the development of tree islands. Commercially available peat bags were used as the medium for the growth and establishment of potted native tree saplings. The pop-up configuration floated initially and provided additional elevation to minimize inundation, with a single native tree species sapling and a single tree fertilizer spike. During a 3 year study involving 105 pop-ups, most plants survived (80%) and many thrived. Determining whether this technique can establish trees on a degraded tree island will require longer studies and extensive field tests.

This protocol describes a simple, cost-effective tree planting technique for restoring degraded Everglades tree islands that experience inundation. The design creates an island (pop-up) which floats initially and adds elevation to promote tree survival and growth under flooded conditions.

Una sencilla técnica de plantación para restablecer los árboles donde se produce la inundación frecuente

Many of the Everglades tree islands have lost elevation over the past century and most of their trees have died such that they are now covered with ...

Optimized Procedure for Determining the Adsorption of Phosphonates onto Granular Ferric Hydroxide using a Miniaturized Phosphorus Determination Method

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide (GFH), with little effort and high reliability. The phosphonate, e.g., nitrilotrimethylphosphonic acid (NTMP), is brought into contact with the GFH in a rotator in a solution buffered by an organic acid (e.g., acetic acid) or Good buffer (e.g., 2-(N-morpholino)ethanesulfonic acid) [MES] and N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid [CAPSO]) in a concentration of 10 mM for a specific time in 50 mL centrifuge tubes. Subsequently, after membrane filtration (0.45 &#181;m pore size), the total phosphorus (total P) concentration is measured using a specifically developed determination method (ISOmini). This method is a modification and simplification of the ISO 6878 method: a 4 mL sample is mixed with H2SO4 and K2S2O8 in a screw cap vial, heated to 148-150 &#176;C for 1 h and then mixed with NaOH, ascorbic acid and acidified molybdate with antimony(III) (final volume of 10 mL) to produce a blue complex. The color intensity, which is linearly proportional to the phosphorus concentration, is measured spectrophotometrically (880 nm). It is demonstrated that the buffer concentration used has no significant effect on the adsorption of phosphonate between pH 4 and 12. The buffers, therefore, do not compete with the phosphonate for adsorption sites. Furthermore, the relatively high concentration of the buffer requires a higher dosage concentration of oxidizing agent (K2S2O8) for digestion than that specified in ISO 6878, which, together with the NaOH dosage, is matched to each buffer. Despite the simplification, the ISOmini method does not lose any of its accuracy compared to the standardized method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide, with little effort and high reliability. In a buffered solution, the phosphonate is brought into contact with the adsorbent using a rotator and then analyzed via a miniaturized phosphorus determination method.

Procedimiento optimizado para la determinación de la adsorción de los fosfonatos en hidróxido férrico Granular utilizando un método de determinación de fósforo miniaturizados

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric ...