This work was funded, in part, by the Great Lakes Fishery Commission and the Annis Water Resources Institute. Use of trade, product, or firm names does not imply endorsement by the U. S. Government. This article is Contribution 1867 of the U. S. Geological Survey Great Lakes Science Center.

1 Laboratoire Expérience <ol><li> Obtenir le poisson proie à introduire dans les poissons des prédateurs pendant l&#39;expérience. De préférence, ces poissons proies doivent être capturés dans le domaine, congelés et conservés à -30 ° C environ. Envisager des opérations de pêche commerciale comme une source potentielle de poissons proies. </li><li> Présentez le poisson prédateur dans les réservoirs de laboratoire à utiliser pour l&#39;expérience. Jusqu&#39;à 15 poissons prédateurs ont été introduits dans chacune des cuves de 870 L, et jusqu&#39;à 30 poissons prédateurs ont été introduits dans chacun des réservoirs 2380-L dans des études antérieures 16,18. </li><li> Acclimater les poissons prédateurs à un régime alimentaire du poisson proie choisie. Une fois acclimatés, le poisson prédateur doit rester sur ce régime pendant 1-3 mois avant de commencer l&#39;expérience. </li><li> Mettez de côté les échantillons de poissons proies en choisissant au hasard 10 à 20 échantillons composites du lot de poissons proies. Nombre de poissons proies dans un échantillon composite peut varier de 3 à 100, en fonction de la taille de la proiepoissons. Chaque échantillon composite doit être double emballage, congelés et stockés à -30 ° C environ. </li><li> Initier l&#39;expérience en sacrifiant 30 à 50% des poissons dans chacun des réservoirs. <ol><li> Pour euthanasier les poissons, mélanger 8 g de Finquel avec 45 L d&#39;eau dans un grand récipient en plastique, puis placez le poisson dans le récipient avec la solution Finquel. </li><li> Une fois euthanasiés, placer tous les poissons sacrifiés d&#39;un réservoir dans un sac, puis double sac, et conserver à -30 ° C jusqu&#39;au moment de la transformation. </li><li> Peser chacun des poissons restant dans chacun des réservoirs, et noter les poids; un anesthésique sera probablement nécessaire de procéder à la pesée. </li><li> Pour anesthésier le poisson, mélanger 4,6 g de Finquel avec 45 L d&#39;eau dans un grand récipient en plastique, puis placez le poisson dans le récipient avec la solution Finquel. </li><li> Attendez quelques minutes pour l&#39;anesthésie pour prendre effet avant la pesée. </li></ol></li><li> Chaque jour de l&#39;expérience, décongeler unquantité appropriée de poissons proies, et couper le poisson en morceaux proie pesant environ 1 à 5 g. Peser la quantité de poissons proies pour être placé dans chacune des cuves, puis déposez les morceaux de poisson de proie dans chaque cuve et laisser le poisson prédateur environ 1 heure pour se nourrir. Ensuite, retirer tous les restes de nourriture, de permettre la nourriture à l&#39;air sec pendant environ 20 min, puis peser la nourriture non consommée pour chacun des réservoirs. Enregistrer la quantité de nourriture placée dans le réservoir et la quantité de la nourriture non consommée pour chacun des réservoirs chaque jour. REMARQUE: Pour l&#39;expérience représentative, la truite de lac ont été nourris autant de nourriture qu&#39;ils consomment au cours d&#39;une période d&#39;alimentation chaque jour 18. Cependant, le poisson prédateur pourrait également être placé sur des rations fixes 16,19. </li><li> Mettre fin à l&#39;expérience en sacrifiant tous les poissons prédateurs en restant dans chacun des réservoirs. Pour euthanasier les poissons, mélanger 8 g de Finquel avec 45 L d&#39;eau dans un grand récipient en plastique, puis placez le poisson dans le récipient avec la solution Finquel. Enregistrez til poids de chacun des poissons sacrifié. Pour des résultats fiables, l&#39;expérience doit fonctionner pendant au moins 100 jours, de préférence pendant au moins 130 jours. Placez tous les poissons d&#39;un réservoir dans un sac, puis double sac, et conserver à -30 ° C jusqu&#39;au moment de la transformation. </li></ol> 2. poisson homogénéisation <ol><li> Sélectionnez un ensemble de poissons prédateurs et / ou composites de poissons proies pour la décongélation. Autoriser les composites à décongeler partiellement. Chaque composite peut exiger de 0,5 à 1 heure pour homogénéiser. </li><li> En utilisant les mélangeurs appropriés taille, homogénéiser chacun des composites. Pour chaque composé, placer un échantillon (de 50 à 100 g) de l&#39;homogénat dans un récipient nettoyé, rincé à l&#39;acétone, et marqué. Puis coiffer le récipient et stocker le pot à environ -30 ° C jusqu&#39;à ce que le temps de traitement. </li><li> Laver tous les équipements utilisés pour homogénéiser le poisson, puis rincer correctement avec de l&#39;eau distillée et de méthanol, entre les échantillons. </li></ol> 3 Extraction <ol><li> Peser 20,0 gde décongelé les tissus de poissons homogénéisé dans un bêcher de 200 ml. </li><li> Ajouter environ 40 g de sulfate de sodium et mélanger avec une spatule. </li><li> Ajouter la solution de pointe de substitution contenant des congénères 30, 61, 161, 166 et pointes à une concentration qui donne une concentration finale de 20 ng / ml dans l&#39;extrait. </li><li> Permettre à l&#39;échantillon à sécher à la température ambiante tout en mélangeant toutes les 20 minutes. </li><li> Laisser l&#39;échantillon pour atteindre une consistance de sable sec, après quoi l&#39;échantillon est prêt pour l&#39;extraction. </li><li> Mettre en place l&#39;appareil d&#39;extraction Soxhlet avec un ballon de 500 ml contenant des copeaux de téflon d&#39;ébullition, Soxhlet, et du condenseur. </li><li> Ajouter le mélange de poisson séché à une cosse de verre avec un disque de fond ou fritte à gros papier dé à coudre. </li><li> Ajouter 150 ml de 50% d&#39;hexane et 50% de dichlorométhane dans le bêcher utilisé pour mélanger l&#39;échantillon et tout en raclant les parois du bêcher avec une spatule. </li><li> Transférer le solvant au début de la Soxhlet avec le ballon attaché et lui permettre de défiler dans le Soxhlet etdans le ballon. </li><li> Répétez une seconde fois avec 150 ml. </li><li> Placer le ballon de Soxhlet avec du joint sur l&#39;élément de chauffage et de fixer le condenseur. </li><li> Mettez l&#39;élément chauffant et amener le solvant à ébullition douce, puis extraire pour un minimum de 16 heures de s&#39;assurer que l&#39;eau froide est fournie dans les condenseurs. </li><li> Après avoir laissé le solvant refroidir, vérifier pour voir si l&#39;un des flacons d&#39;échantillons contiennent de l&#39;eau. Dans le cas des flacons contenant de l&#39;eau, ajouter du sulfate de sodium et mélanger jusqu&#39;à ce que l&#39;eau est absorbée par le sulfate de sodium. </li><li> Concentrer l&#39;échantillon à l&#39;aide d&#39;un échantillon de concentration d&#39;azote ou un Kaderna danois (KD) installation de la verrerie avec un bain d&#39;eau chaude. </li><li> Laisser l&#39;échantillon à évaporer à un volume inférieur à 2 ml, puis porter à un volume final de 5 ml à l&#39;aide de petits lavages d&#39;hexane pour transférer l&#39;échantillon à partir de la verrerie utilisée dans une fiole jaugée de 5 mL. </li><li> Transférer dans un flacon de 10 ml et l&#39;étiquette avec l&#39;information d&#39;échantillon. </li></ol><ol><li> Préparation du gel de silice acidifiée par addition de 44 g d&#39;acide sulfurique concentré à 100 g de gel de silice activé. </li><li> Ajouter 10 g de gel de silice acidifiée dans une colonne de chromatographie contenant un petit petit tampon de laine de verre au fond. </li><li> Ajouter 1 ml d&#39;extrait de l&#39;échantillon à la colonne après pré-nettoyage de la colonne avec 10 ml d&#39;hexane. </li><li> On élue la colonne avec 20 ml d&#39;hexane et de recueillir dans conique tube en verre de 20 ml. </li><li> Placer le tube de verre sur le dispositif évaporateur d&#39;azote (N-Vap) sous un courant d&#39;azote et immergé dans l&#39;eau chaude. </li><li> Evaporer à moins de 1 ml, mais pas jusqu&#39;à siccité. </li><li> Retirer de l&#39;appareil N-Vap et transfert à 1 ml fiole jaugée avec de petits lavages d&#39;hexane. </li><li> Transfert à un échantillonneur automatique 1,8 ml flacon étiqueté avec des informations échantillon. </li><li> De Spike 4 pi de standard interne dans le flacon. L&#39;échantillon est maintenant prêt pour l&#39;analyse. </li></ol> 5. Analyse par chromatographie en phase gazeuse - spectrométrie de masse à ionisation chimique utilisant négatif <ol><li> Utiliser les normes pour calibrer l&#39;instrument: Les normes sont disponibles dans des mélanges constitués de groupes de congénères bien séparés. Mélanges 1-5 composent de presque tous les congénères présents dans Arochlors 1016, 1221, 1232, 1242, 1248, 1254, et 1260 Mix 1 est utilisé comme un étalonnage mélange multi-niveaux, et la linéarité du système est confirmé par la préparation d&#39;au moins cinq niveaux d&#39;étalonnage à des concentrations comprises entre 2 et 100 ng / ml. Mélanges 2-5 sont utilisés comme étalonnages ponctuelles pour chaque congénère. </li><li> Mettre en place la Chromatographie - Système de spectrométrie de masse en mode d&#39;ionisation chimique négative avec l&#39;hydrogène comme gaz vecteur (1 ml / min) et le méthane comme gaz réactif. </li><li> Utilisez un verre de silice, colonne capillaire (60 m × 0,25 mm de diamètre interne) recouvert de DB-XLB à l&#39;épaisseur du film 0,25 um pour la séparation. Programme de température du four 60 à 212 ° C à 25 ° C / min, puis à 260 ° C à 1 ° C / min, puis à 280 ° C à 4 ° C / min, avec un temps de maintien finale de 4 min. températures de l&#39;injecteur et de la ligne de transfert devraient être fixés à 280 ° C. Injecter de 1 à 2 ml de l&#39;échantillon à l&#39;aide du mode d&#39;injection sans division. </li><li> Analyser toutes les normes et les échantillons par la méthode standard interne à l&#39;aide 13 décachlorobiphényle C marqué. </li><li> Effectuez une vérification de l&#39;étalonnage initial en exécutant une deuxième norme de source et Aroclors 1242 et 1260, puis comparer les valeurs prédites pour les congénères Arochlore avec les quantités observées de cette procédure de contrôle. </li><li> Une fois que la procédure d&#39;étalonnage initiale a été réalisée avec succès, l&#39;analyse complète de tous les échantillons. Exécutez un étalonnage vérifier tous les dix échantillons, en utilisant l&#39;un des mélanges d&#39;étalonnage de l&#39;étalonnage initial. </li></ol> 6 Calcul de l&#39;efficacité de transfert net trophique <ol><li> Calculer l&#39;efficacité du transfert trophique net, γ, pour chaque combinaison oréservoir de f et PCB congénères en utilisant l&#39;équation suivante: <img alt="L&#39;équation 1" fo:content-width="2in" src="/files/ftp_upload/51496/51496eq1.jpg" /> , Où [PCB f] est la concentration moyenne des poissons prédateurs dans le réservoir à la fin de l&#39;expérience PCB congénères, W f est le poids moyen des poissons prédateurs dans le réservoir à la fin de l&#39;expérience, [PCB i] est la concentration en PCB congénère moyen des poissons prédateurs dans le réservoir au début de l&#39;expérience, W i est le poids moyen des poissons prédateurs au début de l&#39;expérience, et la quantité de PCB congénère ingéré se rapporte au poids de l&#39; congénère PCB ingérés, en moyenne, par chaque touladi dans le réservoir au cours de l&#39;expérience. </li><li> Calculer le dénominateur dans l&#39;équation ci-dessus en multipliant la concentration moyenne de congénères de PCB dans les composites de poissons proies par le montant moyen (poids) des poissons proies consommées par les poissons prédateurs dans le dur de réservoirment toute la durée de l&#39;expérience. </li></ol>

<ol>
	<li>Madenjian, C. P., Carpenter, S. R., Rand, P. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Why+are+the+PCB+concentrations+of+salmonine+individuals+from+the+same+lake+so+highly+variable?.">Why are the PCB concentrations of salmonine individuals from the same lake so highly variable?.</a> Canadian Journal of Fisheries and Aquatic Sciences. 51 (4), 800-807 (1994).</li><li>Madenjian, C. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Net+trophic+transfer+efficiency+of+PCBs+to+Lake+Michigan+coho+salmon+from+their+prey.">Net trophic transfer efficiency of PCBs to Lake Michigan coho salmon from their prey.</a> Environmental Science and Technology. 32 (20), 3063-3067 (1998).</li><li>Thomann, R. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioaccumulation+model+of+organic+chemical+distribution+in+aquatic+food+chains.">Bioaccumulation model of organic chemical distribution in aquatic food chains.</a> Environmental Science and Technology. 23 (6), 699-707 (1989).</li><li>Calabrese, E. J., Baldwin, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Performing ecological risk assessments. , (1993).</li><li>Madenjian, C. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variation+in+net+trophic+transfer+efficiencies+among+21+PCB+congeners.">Variation in net trophic transfer efficiencies among 21 PCB congeners.</a> Environmental Science and Technology. 33 (21), 3768-3773 (1999).</li><li>Jackson, L. J., Schindler, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Field+estimates+of+net+trophic+transfer+of+PCBs+from+prey+fishes+to+Lake+Michigan+salmonids.">Field estimates of net trophic transfer of PCBs from prey fishes to Lake Michigan salmonids.</a> Environmental Science and Technology. 30 (6), 1861-1865 (1996).</li><li>Gobas, F. A. P. C., Muir, D. C. G., Mackay, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamics+of+dietary+bioaccumulation+and+faecal+elimination+of+hydrophobic+organic+chemicals+in+fish.">Dynamics of dietary bioaccumulation and faecal elimination of hydrophobic organic chemicals in fish.</a> Chemosphere. 17 (5), 943-962 (1988).</li><li>Madenjian, C. P., O&#8217;Connor, D. V., Rediske, R. R., O&#8217;Keefe, J. P., Pothoven, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Net+trophic+transfer+efficiencies+of+polychlorinated+biphenyl+congeners+to+lake+whitefish+(Coregonus+clupeaformis)+from+their+food.">Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake whitefish (Coregonus clupeaformis) from their food.</a> Environmental Toxicology and Chemistry. 27 (3), 631-636 (2008).</li><li>Isosaarl, P., Kiviranta, H., Lie, &. #. 2. 1. 6. ;., Lundebye, A. K., Ritchie, G., Vartiainen, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accumulation+and+distribution+of+polychlorinated+dibenzo-p-dioxin,+dibenzofuran,+and+polychlorinated+biphenyl+congeners+in+Atlantic+salmon+(Salmo+salar).">Accumulation and distribution of polychlorinated dibenzo-p-dioxin, dibenzofuran, and polychlorinated biphenyl congeners in Atlantic salmon (Salmo salar).</a> Environmental Toxicology and Chemistry. 23 (7), 1672-1679 (2004).</li><li>Buckman, A. H., Brown, S. B., Hoekstra, P. F., Solomon, K. R., Fisk, A. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toxicokinetics+of+three+polychlorinated+biphenyl+technical+mixtures+in+rainbow+trout+(Oncorhynchus+mykiss).">Toxicokinetics of three polychlorinated biphenyl technical mixtures in rainbow trout (Oncorhynchus mykiss).</a> Environmental Toxicology and Chemistry. 23 (7), 1725-1736 (2004).</li><li>Burreau, S., Axelman, J., Broman, D., Jakobsson, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dietary+uptake+in+pike+(Esox+lucius)+of+some+polychlorinated+biphenyls,+polychlorinated+naphthalenes+and+polybrominated+diphenyl+ethers+administered+in+natural+diet.">Dietary uptake in pike (Esox lucius) of some polychlorinated biphenyls, polychlorinated naphthalenes and polybrominated diphenyl ethers administered in natural diet.</a> Environmental Toxicology and Chemistry. 16 (12), 2508-2513 (1997).</li><li>Madenjian, C. P., DeSorcie, T. J., Stedman, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ontogenic+and+spatial+patterns+in+diet+and+growth+of+lake+trout+in+Lake+Michigan.">Ontogenic and spatial patterns in diet and growth of lake trout in Lake Michigan.</a> Transactions of the American Fisheries Society. 127 (2), 236-252 (1998).</li><li>Paterson, G., Whittle, D. M., Drouillard, K. G., Haffner, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Declining+lake+trout+(Salvelinus+namaycush)+energy+density:+are+there+too+many+salmonid+predators+in+the+Great+Lakes?.">Declining lake trout (Salvelinus namaycush) energy density: are there too many salmonid predators in the Great Lakes?.</a> Canadian Journal of Fisheries and Aquatic Sciences. 66 (6), 919-932 (2009).</li><li>Madenjian, C. P., O&#8217;Connor, D. V., Nortrup, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+approach+toward+evaluation+of+fish+bioenergetics+models.">A new approach toward evaluation of fish bioenergetics models.</a> Canadian Journal of Fisheries and Aquatic Sciences. 57 (5), 1025-1032 (2000).</li><li>Madenjian, C. P., Pothoven, S. A., Kao, Y. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reevaluation+of+lake+trout+and+lake+whitefish+bioenergetics+models.">Reevaluation of lake trout and lake whitefish bioenergetics models.</a> Journal of Great Lakes Research. 39 (2), 358-364 (2013).</li><li>Madenjian, C. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+lake+whitefish+bioenergetics+model.">Evaluation of a lake whitefish bioenergetics model.</a> Transactions of the American Fisheries Society. 135 (1), 61-75 (2006).</li><li>Madenjian, C. P., O&#8217;Connor, D. V., Chernyak, S. M., Rediske, R. R., O&#8217;Keefe, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+a+chinook+salmon+(Oncorhynchus+tshawytscha)+bioenergetics+model.">Evaluation of a chinook salmon (Oncorhynchus tshawytscha) bioenergetics model.</a> Canadian Journal of Fisheries and Aquatic Sciences. 61 (4), 627-635 (2004).</li><li>Madenjian, C. P., David, S. R., Rediske, R. R., O&#8217;Keefe, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Net+trophic+transfer+efficiencies+of+polychlorinated+biphenyl+congeners+to+lake+trout+(Salvelinus+namaycush)+from+its+prey.">Net trophic transfer efficiencies of polychlorinated biphenyl congeners to lake trout (Salvelinus namaycush) from its prey.</a> Environmental Toxicology and Chemistry. 31 (12), 2821-2827 (2012).</li><li>Madenjian, C. P., O'Connor, D. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laboratory+evaluation+of+a+lake+trout+bioenergetics+model.">Laboratory evaluation of a lake trout bioenergetics model.</a> Transactions of the American Fisheries Society. 128 (5), 802-814 (1999).</li><li>Ballschmiter, K., Bacher, R., Mennel, A., Fischer, R., Riehle, U., Swerev, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+determination+of+chlorinated+biphenyls,+chlorinated+dibenzodioxins,+and+chlorinated+dibenzofurans+by+GC-MS.">The determination of chlorinated biphenyls, chlorinated dibenzodioxins, and chlorinated dibenzofurans by GC-MS.</a> HRC Journal of High Resolution Chromatography. 15 (4), 260-270 (1992).</li><li>Madenjian, C. P., David, S. R., Pothoven, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+activity+and+energy+budget+balancing+algorithm+on+laboratory+performance+of+a+fish+bioenergetics+model.">Effects of activity and energy budget balancing algorithm on laboratory performance of a fish bioenergetics model.</a> Transactions of the American Fisheries Society. 141 (5), 1328-1337 (2012).</li><li>Lieb, A. J., Bills, D. D., Sinnhuber, R. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accumulation+of+dietary+polychlorinated+biphenyls+(Aroclor+1254)+by+rainbow+trout.">Accumulation of dietary polychlorinated biphenyls (Aroclor 1254) by rainbow trout.</a> Journal of Agricultural and Food Chemistry. 22 (4), 638-642 (1974).</li><li>Niimi, A. J., Oliver, B. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biological+half-lives+of+polychlorinated+biphenyl+(PCB)+congeners+in+whole+fish+and+muscle+of+rainbow+trout+(Salmo+gairdneri).">Biological half-lives of polychlorinated biphenyl (PCB) congeners in whole fish and muscle of rainbow trout (Salmo gairdneri).</a> Canadian Journal of Fisheries and Aquatic Sciences. 40 (9), 1388-1394 (1983).</li><li>Gobas, F. A. P. C., Wilcockson, J. B., Russell, R. W., Haffner, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanism+of+biomagnification+in+fish+under+laboratory+and+field+conditions.">Mechanism of biomagnification in fish under laboratory and field conditions.</a> Environmental Science and Technology. 33 (1), 133-141 (1999).</li><li>Dmitrovic, J., Chan, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+polychlorinated+biphenyl+congeners+in+human+milk+by+gas+chromatography+&#8211;+negative+chemical+ionization+mass+spectrometry+after+sample+clean-up+by+solid-phase+extraction.">Determination of polychlorinated biphenyl congeners in human milk by gas chromatography &#8211; negative chemical ionization mass spectrometry after sample clean-up by solid-phase extraction.</a> Journal of Chromatography B. 778 (1-2), 147-155 (2002).</li><li>Zorn, M. E., Gibbons, R. D., Sonzogni, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Weighted+least-squares+approach+to+calculating+limits+of+detection+and+quantification+by+modeling+variability+as+a+function+of+concentration.">Weighted least-squares approach to calculating limits of detection and quantification by modeling variability as a function of concentration.</a> Analytical Chemistry. 69 (15), 3069-3075 (1997).</li></ol>

Pour des estimations plus précises de γ, l&#39;expérimentateur doit être capable de suivre avec précision à la fois la quantité d&#39;aliments placés dans chacun des réservoirs et la quantité de la nourriture non consommée dans chacun des réservoirs, au cours de l&#39;expérience. Pour ce faire, l&#39;expérimentateur doit être en mesure d&#39;éliminer tous les restes de nourriture provenant des réservoirs et de déterminer avec précision son poids. En plus de suivi précis de la nourriture réellement c...

Of all of the factors affecting the rate at which fish accumulate contaminants, the efficiency with which fish retain contaminants from the food that they eat is one of the most important1-3. Risk assessment models have been developed to predict future risks to both people and wildlife eating contaminated fish under various scenarios of environmental contamination, and the reliability of these predictions critically depends on the accuracy of the estimates of the efficiency at which fish retain contaminants from their food4.
The efficiency with which the contaminant in the food ingested by the predator is transported through the gut wall is known as gross trophic transfer efficiency5. A portion of the quantity of the contaminant transported through the gut wall of the predator may eventually be lost through depuration and/or metabolic transformation. The efficiency with which the contaminant in the food ingested by the predator is retained by the predator, including any losses due to elimination and metabolic transformation, is known as net trophic transfer efficiency6.
Gross trophic transfer efficiency of organic contaminants to fish from their prey appears to vary with the contaminant&#8217;s chemical properties, including lipid affiliation as measured by the octanol-water partition coefficient, Kow3,7. According to an empirical relationship developed by Thomann3, gross trophic transfer efficiency is relatively high when log Kow is equal to a value between 5 and 6. Gross trophic transfer efficiency declines exponentially at a rate of 50% per unit of log Kow as log Kow increases from 6 to 10, according to the Thomann3 relationship.
Nevertheless, the gross and net trophic transfer efficiencies of polychlorinated biphenyl (PCB) congeners to fish from their prey do not appear to follow the Thomann3 relationship in most cases. Although the trophic transfer efficiencies of PCB congeners to lake whitefish (Coregonus clupeaformis) from its food followed the relationship proposed by Thomann8, trophic transfer efficiencies of PCB congeners were either just weakly related or not related at all to log Kow for Atlantic salmon (Salmo salar)9, rainbow trout (Oncorhynchus mykiss)10, coho salmon (Oncorhynchus kisutch)11, and northern pike (Esox lucius)11.
The overall goal of this study was to present a laboratory technique for estimating the net trophic transfer efficiencies of PCB congeners to a piscivorous fish from its prey. Lake trout (Salvelinus namaycush) was chosen as the piscivorous fish for our experiment because lake trout are relatively easy to maintain in laboratory tanks. Bloater (Coregonus hoyi) was selected as the prey fish to be fed to the lake trout because bloater is eaten by lake trout in its natural setting12. In addition, we determined whether the net trophic transfer efficiencies for lake trout estimated from our laboratory experiment followed the Thomann3 relationship. We also determined whether the degree of activity by the lake trout had a significant effect on net trophic transfer efficiency (&#947;) of the PCB congeners. Activity by lake trout in the Laurentian Great Lakes is believed to have recently increased because changes in the food webs have caused lake trout to allocate more energy toward searching for food13. Lake trout were forced to exercise in one set of tanks by subjecting these lake trout to relatively high flow rates, whereas the other lake trout were permitted to remain relatively inactive by subjecting them to relatively low flow rates. Finally, the specific details of our laboratory procedure that need to be carefully followed to ensure the highest degree of accuracy in the &#947; estimates and to make the laboratory results applicable to the field are discussed, as well as future directions for research building on our laboratory technique. Net trophic transfer efficiency can be estimated both in the laboratory and in the field, and advantages and disadvantages are associated with both approaches. Accuracy in the estimate of &#947; depends on the accuracy of the estimate of food consumption. The amount of food eaten by fish in the laboratory can be accurately determined when proper protocols are followed, whereas the amount of food eaten by fish in the field is typically estimated via bioenergetics modeling. Use of bioenergetics modeling to derive the amount of food eaten has the potential to introduce a substantial amount of uncertainty into the estimates of food consumption. Fish bioenergetics models have been shown to estimate food consumption with no detectable bias for the case of lake trout14,15, but considerable bias in bioenergetics model estimates of food consumption has been detected for the case of lake whitefish15,16. On the other hand, estimates of net trophic transfer efficiency estimated in the laboratory may not be applicable to the field due to a difference in feeding rates between the laboratory and the field17. Evidence from both the laboratory and the field suggest that feeding rate can influence &#947;14,17.
The methodology used in the present study for estimating &#947; in the laboratory is applicable to situations where the predator fish is fed prey fish, and the amount of prey fish eaten by the predator can be accurately tracked. To accomplish this, the experimenter must weigh all of the food before placement in the tank; and the experimenter must be able to remove all of the uneaten food from the tank, and then weigh the uneaten food. In addition, an adequate suite of mixers and blenders should be available to obtain a sufficient degree of homogenization of the samples of both predator and prey fish. Finally, the gas chromatography &#8211; mass spectrometry instrumentation used to determine the PCB congener concentrations must be capable of detecting and quantifying individual PCB congeners at relatively low concentrations.

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			<td height="21" style="height:21px;width:259px;">870-L fiberglass tanks</td>
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			<td style="width:167px;">Eugenol could also be used as an anesthetic.</td>
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			<td height="21" style="height:21px;width:259px;">Sodium sulfate, anhydrous - granular</td>
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			<td style="width:87px;">Wilmad-Lab Glass</td>
			<td style="width:119px;">LG-7070-114</td>
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			<td style="width:119px;">919120</td>
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			<td style="width:87px;">Labconco</td>
			<td style="width:119px;">7910000</td>
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			<td height="21" style="height:21px;width:259px;">N-Vap nitrogen concentrator</td>
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			<td height="35" style="height:35px;width:259px;">Soxhlet extraction glassware (500 mL)</td>
			<td style="width:87px;">Wilmad-Lab Glass</td>
			<td style="width:119px;">&#160;LG-6900-104</td>
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			<td height="35" style="height:35px;width:259px;">Hexane</td>
			<td style="width:87px;">Burdick &#38; Jackson&#160;</td>
			<td style="width:119px;">Cat. 211-4</td>
			<td></td>
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			<td height="35" style="height:35px;width:259px;">Dichloromethane</td>
			<td style="width:87px;">Burdick &#38; Jackson&#160;</td>
			<td style="width:119px;">Cat. 300-4</td>
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			<td height="21" style="height:21px;width:259px;">Silica gel</td>
			<td style="width:87px;">BDH</td>
			<td style="width:119px;">Cat. BDH9004-1KG</td>
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			<td height="35" style="height:35px;width:259px;">Labl Line 5000 mult-unit extraction heater</td>
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			<td height="35" style="height:35px;width:259px;">Agilent 5973 GC/MS with chemical ionization</td>
			<td style="width:87px;">Agilent</td>
			<td style="width:119px;">5973N</td>
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			<td height="52" style="height:52px;width:259px;">Internal standard solution&#160;</td>
			<td style="width:87px;">Cambridge Isotope Laboratories</td>
			<td style="width:119px;">EC-1410-1.2</td>
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			<td height="21" style="height:21px;width:259px;">PCB congener calibration standards</td>
			<td style="width:87px;">Accustandard</td>
			<td style="width:119px;">C-CSQ-SET</td>
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			<td height="21" style="height:21px;width:259px;">DB-XLB column (60m x 0.25mm, 0.25 micron)</td>
			<td style="width:87px;">Agilent/ J&#38;W</td>
			<td style="width:119px;">122-1262</td>
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laboratory estimation of net trophic transfer efficiencies of pcb congeners to lake trout (salvelinus namaycush) from its prey

Une technique pour laboratoire estimation de rendement net trophique de transfert (γ) de polychlorobiphényles (PCB) chez les poissons piscivores à partir de leur proie est décrite ici. Au cours d&#39;une expérience de laboratoire de 135 jours, nous avons nourri de fumage (Coregonus hoyi) qui avaient été pêchés dans le lac Michigan au lac de fontaine (Salvelinus namaycush) conservés dans huit réservoirs de laboratoire. Fumage est une proie naturelle pour le touladi. Dans quatre des réservoirs, un débit relativement élevé a été utilisé pour assurer une activité relativement élevée par la truite de lac, alors qu&#39;un faible débit a été utilisé dans les quatre autres réservoirs, ce qui permet une faible activité du touladi. Sur une base réservoir par réservoir, la quantité de nourriture ingérée par le touladi sur chaque jour de l&#39;expérience a été enregistrée. Chaque truite de lac a été pesé au début et à la fin de l&#39;expérience. Quatre à neuf touladi de chacun des huit réservoirs ont été sacrifiés au début de l&#39;expérience, et les 10 touladi restant dans chacun des réservoirs étaient euthanlisés à la fin de l&#39;expérience. Nous avons déterminé les concentrations de 75 congénères de BPC dans le touladi au début de l&#39;expérience, dans le touladi à la fin de l&#39;expérience, et bouffis nourris à la truite de lac pendant l&#39;expérience. Sur la base de ces mesures, γ a été calculé pour chacun des 75 congénères de PCB dans chacun des huit réservoirs. Mean γ a été calculé pour chacun des 75 congénères de PCB pour la truite de lac à la fois active et inactive. Parce que l&#39;expérience a été répétée dans huit réservoirs, l&#39;erreur-type sur moyenne γ peuvent être estimés. Les résultats de ce type d&#39;expérience sont utiles dans les modèles d&#39;évaluation des risques pour prédire le risque futur pour les humains et la faune de manger du poisson contaminé, selon divers scénarios de contamination de l&#39;environnement.

Le touladi a montré une quantité substantielle de la croissance au cours de l&#39;expérience, comme les touladis initiales signifient poids variaient de 694 à 907 g, tandis que les touladis finales le poids moyen variait de 853 à 1566 g (tableau 1). La quantité moyenne de nourriture consommée par une truite de lac au cours de l&#39;expérience de 135 jours variait de 641 à 2649 g. Concentrations PCB congénères moyenne chez la truite du lac a augmenté au cours de l&#39;expérience, car les con...

Watch this Scientific Journal Video about Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout Salvelinus namaycush from Its Prey at JoVE.com

Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout Salvelinus namaycush from Its Prey

Une technique pour laboratoire estimation de l&#39;efficacité du transfert trophique net de polychlorobiphényles (PCB) chez les poissons piscivores à partir de leur proie est présenté. Afin de maximiser l&#39;applicabilité des résultats de laboratoire sur le terrain, les poissons piscivores doit être nourri poissons proies qui sont généralement consommés dans le domaine.

Laboratoire Estimation des gains en efficience de transfert net trophiques des congénères de PCB dans le lac Trout (<em&gt; Salvelinus namaycush</em&gt;) De sa proie

A technique for laboratory estimation of net trophic transfer efficiency (&#947;) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from ...

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Research

JoVE Journal

Environment

Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout (Salvelinus namaycush) from Its Prey

10.9K vues.  U. S. Geological Survey.  Une technique pour laboratoire estimation de l'efficacité du transfert trophique net de polychlorobiphényles (PCB) chez les poissons piscivores à partir de leur proie est présenté. Afin de maximiser l'applicabilité des résultats de laboratoire sur le terrain, les poissons piscivores doit être nourri poissons proies qui sont généralement consommés dans le domaine. 

Vidéo: Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout Salvelinus namaycush from Its Prey

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.

Déterminé en laboratoire Phosphore Flux de sédiments lacustres en tant que mesure de phosphore interne Chargement en cours

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

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Environnement

A Fish-feeding Laboratory Bioassay to Assess the Antipredatory Activity of Secondary Metabolites from the Tissues of Marine Organisms

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with the goal of examining the ecological functions of secondary metabolites from the tissues of marine organisms. The result has been a progression of protocols that have increasingly refined the ecological relevance of the experimental approach. Here we present the most up-to-date version of a fish-feeding laboratory bioassay that enables investigators to assess the antipredatory activity of secondary metabolites from the tissues of marine organisms. Organic metabolites of all polarities are exhaustively extracted from the tissue of the target organism and reconstituted at natural concentrations in a nutritionally appropriate food matrix. Experimental food pellets are presented to a generalist predator in laboratory feeding assays to assess the antipredatory activity of the extract. The procedure described herein uses the bluehead, Thalassoma bifasciatum, to test the palatability of Caribbean marine invertebrates; however, the design may be readily adapted to other systems. Results obtained using this laboratory assay are an important prelude to field experiments that rely on the feeding responses of a full complement of potential predators. Additionally, this bioassay can be used to direct the isolation of feeding-deterrent metabolites through bioassay-guided fractionation. This feeding bioassay has advanced our understanding of the factors that control the distribution and abundance of marine invertebrates on Caribbean coral reefs and may inform investigations in diverse fields of inquiry, including pharmacology, biotechnology, and evolutionary ecology.

This bioassay employs a model predatory fish to assess the presence of feeding-deterrent metabolites from organic extracts of the tissues of marine organisms at natural concentrations using a nutritionally comparable food matrix.

Un poisson-alimentation Laboratoire d&#39;essais biologiques pour évaluer l&#39;activité antiprédatrices des métabolites secondaires dans les tissus d&#39;organismes marins

Marine chemical ecology is a young discipline, having emerged from the collaboration of natural products chemists and marine ecologists in the 1980s with ...

Automated Gel Size Selection to Improve the Quality of Next-generation Sequencing Libraries Prepared from Environmental Water Samples

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA libraries are needed for optimal results from next-generation sequencing. Environmental samples such as water may have low quality and quantities of DNA as well as contaminants that co-precipitate with DNA. The mechanical and enzymatic processes involved in extraction and library preparation may further damage the DNA. Gel size selection enables purification and recovery of DNA fragments of a defined size for sequencing applications. Nevertheless, this task is one of the most time-consuming steps in the DNA library preparation workflow. The protocol described here enables complete automation of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments. 
In this study, we describe a high-throughput approach to prepare high quality DNA libraries from freshwater samples that can be applied also to other environmental samples. We used an indirect approach to concentrate bacterial cells from environmental freshwater samples; DNA was extracted using a commercially available DNA extraction kit, and DNA libraries were prepared using a commercial transposon-based protocol. DNA fragments of 500 to 800 bp were gel size selected using Ranger Technology, an automated electrophoresis workstation. Sequencing of the size-selected DNA libraries demonstrated significant improvements to read length and quality of the sequencing reads.

This manuscript describes an automated gel size selection approach for purifying DNA fragments for next-generation sequencing. The Ranger Technology provides complete automation of the entire process of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments allowing for high-throughput and high quality next-generation sequencing libraries.

Sélection de la taille Gel automatisé pour améliorer la qualité des bibliothèques de séquençage de prochaine génération Préparé à partir d&#39;échantillons d&#39;eau de l&#39;environnement

Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA ...

Removal of Trace Elements by Cupric Oxide Nanoparticles from Uranium In Situ Recovery Bleed Water and Its Effect on Cell Viability

In situ recovery (ISR) is the predominant method of uranium extraction in the United States. During ISR, uranium is leached from an ore body and extracted through ion exchange. The resultant production bleed water (PBW) contains contaminants such as arsenic and other heavy metals. Samples of PBW from an active ISR uranium facility were treated with cupric oxide nanoparticles (CuO-NPs). CuO-NP treatment of PBW reduced priority contaminants, including arsenic, selenium, uranium, and vanadium. Untreated and CuO-NP treated PBW was used as the liquid component of the cell growth media and changes in viability were determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay in human embryonic kidney (HEK 293) and human hepatocellular carcinoma (Hep G2) cells. CuO-NP treatment was associated with improved HEK and HEP cell viability. Limitations of this method include dilution of the PBW by growth media components and during osmolality adjustment as well as necessary pH adjustment. This method is limited in its wider context due to dilution effects and changes in the pH of the PBW which is traditionally slightly acidic&#160;however; this method could have a broader use assessing CuO-NP treatment in more neutral waters.

Removal of Trace Elements by Cupric Oxide Nanoparticles from Uranium In Situ Recovery Bleed Water and Its Effect on Cell Viability

Production bleed water (PBW) was treated with cupric oxide nanoparticles (CuO-NPs) and cellular toxicity was assessed in cultured human cells. The goal of this protocol was to integrate the native environmental sample into a cell culture format assessing the changes in toxicity due to CuO-NP treatment.

Suppression des éléments traces par Cupric nanoparticules d&#39;oxyde de Uranium<em&gt; In Situ</em&gt; Récupération de l&#39;eau de ressuage et son effet sur la viabilité cellulaire

In situ recovery (ISR) is the predominant method of uranium extraction in the United States. During ISR, uranium is leached from an ore body and extracted ...

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments &#8212; including shallow marine or lacustrine sediments.

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2.

Laboratoire de simulation d&#39;un fer (II) riche système Upwelling précambrien Marine à explorer la croissance des bactéries photosynthétiques

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling ...

Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance

A major concern when developing commercial mycoinsecticides is the kill speed compared to that of chemical insecticides. Therefore, isolation and screening for the selection of a fast-acting, highly virulent entomopathogenic fungus are important steps. Entomopathogenic fungi, such as Metarhizium, Beauveria, and Nomurea, which act by contact, are better suited than Bacillus thuringiensis or nucleopolyhedrosis virus (NPV), which must be ingested by the insect pest. In the present work, we isolated 68 Metarhizium strains from infected insects using a soil dilution and bait method. The isolates were identified by the amplification and sequencing of the ITS1-5.8S-ITS2 and 26S rDNA region. The most virulent strain of Metarhizium anisopliae was selected based on the median lethal concentration (LC50) and time (LT50) obtained in insect bioassays against III-instar larvae of Helicoverpa armigera. The mass production of spores by the selected strain was carried out with solid-state fermentation (SSF) using rice as a substrate for 14 days. Spores were extracted from the sporulated biomass using 0.1% tween-80, and different formulations of the spores were prepared. Field trials of the formulations for the control of an H. armigera infestation in pigeon peas were carried out by randomized block design. The infestation control levels obtained with oil and aqueous formulations (78.0% and 70.9%, respectively) were better than the 63.4% obtained with chemical pesticide.

Development of Metarhizium anisopliae as a Mycoinsecticide: From Isolation to Field Performance

Here, we report the different stages involved in the knowledge-based development of an effective mycoinsecticide, including the isolation, identification, screening, and selection of the "best-fit" entomopathogenic fungus, Metarhizium anisopliae, for the control of insect pests in agriculture.

Développement de<em&gt; Metarhizium anisopliae</em&gt; En tant que myco-insecticide: de l&#39;isolement au rendement sur le terrain

A major concern when developing commercial mycoinsecticides is the kill speed compared to that of chemical insecticides. Therefore, isolation and ...

Procedures of Laboratory Fumigation for Pest Control with Nitric Oxide Gas

Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control. This paper provides detailed protocols for conducting NO fumigation on fresh products and procedures for residue analysis and product quality evaluation. An airtight fumigation chamber containing fresh fruit and vegetables is first flushed with nitrogen (N2) to establish an ultralow oxygen (ULO) environment followed by injection of NO. The fumigation chamber is then kept at a low temperature of 2 - 5 &#176;C for a specified time period necessary to kill a target pest to complete a fumigation treatment. At the end of a fumigation treatment, the fumigation chamber is flushed with N2 to dilute NO prior to opening the chamber to ambient air to prevent the reaction between NO and O2, which produces NO2 and may damage delicate fresh products. At different times after NO fumigation, NO2 in headspace and nitrate and nitrite in liquid samples were measured as residues. Product quality was evaluated after 2 weeks of post-treatment cold storage to determine effects of NO fumigation on product quality. Keeping&#160;O2 from reacting with NO is critical to NO fumigation and is an important part of the protocols. Measuring NO levels is challenging and a practical solution is provided. Possible protocol modifications are also suggested for measuring NO levels in the fumigation chambers as well as residues. NO fumigation has the potential to be a practical alternative to methyl bromide fumigation for postharvest pest control on fresh and stored products. This publication is intended to assist other researchers in conducting NO fumigation research for postharvest pest control and accelerating the development of NO fumigation for practical applications.

This paper describes nitric oxide (NO) fumigation protocols for postharvest pest control. Fumigation chambers are flushed with nitrogen (N2) to establish ultralow oxygen conditions before NO is injected. At the end, chambers are flushed with N2 to dilute NO before exposing products to ambient air to prevent exposure to NO2.

Procédures de laboratoire Fumigation pour Pest Control avec gaz d’oxyde nitrique

Nitric oxide (NO) is a newly discovered fumigant for postharvest pest control. This paper provides detailed protocols for conducting NO fumigation on ...

Adherence of Bacteria to Plant Surfaces Measured in the Laboratory

This manuscript describes a method to measure bacterial binding to axenic plant surfaces in the light microscope and through the use of viable cell counts. Plant materials used include roots, sprouts, leaves, and cut fruits. The methods described are inexpensive, easy, and suitable for small sample sizes. Binding is measured in the laboratory and a variety of incubation media and conditions can be used. The effect of inhibitors can be determined. Situations that promote and inhibit binding can also be assessed. In some cases it is possible to distinguish whether various conditions alter binding primarily due to their effects on the plant or on the bacteria.

An easy method for measuring and characterizing bacterial adhesion to plants, particularly roots and sprouts, is described in this article.

Adhérence des bactéries à planter des Surfaces mesurées en laboratoire

This manuscript describes a method to measure bacterial binding to axenic plant surfaces in the light microscope and through the use of viable cell ...

Ecosystem Fabrication (EcoFAB) Protocols for The Construction of Laboratory Ecosystems Designed to Study Plant-microbe Interactions

Beneficial plant-microbe interactions offer a sustainable biological solution with the potential to boost low-input food and bioenergy production. A better mechanistic understanding of these complex plant-microbe interactions will be crucial to improving plant production as well as performing basic ecological studies investigating plant-soil-microbe interactions. Here, a detailed description for ecosystem fabrication is presented, using widely available 3D printing technologies, to create controlled laboratory habitats (EcoFABs) for mechanistic studies of plant-microbe interactions within specific environmental conditions. Two sizes of EcoFABs are described that are suited for the investigation of microbial interactions with various plant species, including Arabidopsis thaliana, Brachypodium distachyon, and Panicum virgatum. These flow-through devices allow for controlled manipulation and sampling of root microbiomes, root chemistry as well as imaging of root morphology and microbial localization. This protocol includes the details for maintaining sterile conditions inside EcoFABs and mounting independent LED light systems onto EcoFABs. Detailed methods for addition of different forms of media, including soils, sand, and liquid growth media coupled to the characterization of these systems using imaging and metabolomics are described. Together, these systems enable dynamic and detailed investigation of plant and plant-microbial consortia including the manipulation of microbiome composition (including mutants), the monitoring of plant growth, root morphology, exudate composition, and microbial localization under controlled environmental conditions. We anticipate that these detailed protocols will serve as an important starting point for other researchers, ideally helping create standardized experimental systems for investigating plant-microbe interactions.

Ecosystem Fabrication EcoFAB Protocols for The Construction of Laboratory Ecosystems Designed to Study Plant-microbe Interactions

This article describes detailed protocols for ecosystem fabrication of devices (EcoFABs) that enable the studies of plants and plant-microbe interactions in highly controlled laboratory conditions.

Écosystème des protocoles de Fabrication (EcoFAB) pour la Construction des écosystèmes de laboratoire destiné à étudier les Interactions plantes-microorganismes

Beneficial plant-microbe interactions offer a sustainable biological solution with the potential to boost low-input food and bioenergy production. A ...

Laboratory and Field Protocol for Estimating Sheet Erosion Rates from Dendrogeomorphology

Sheet erosion is among the crucial drivers of soil degradation. Erosion is controlled by environmental factors and human activities, which often lead to severe environmental impacts. The understanding of sheet erosion is, consequently, a worldwide issue with implications for both environment and economies. However, the knowledge on how erosion evolves in space and time is still limited, as well as its effects on the environment. Below, we explain a new dendrogeomorphological protocol for deriving eroded soil thickness (Ex) by acquiring accurate microtopographic data using both terrestrial laser scanning (TLS) and microtopographic profile gauges. Additionally, standard dendrogeomorphic procedures, dependent on anatomical variations in root rings, are utilized to establish the timing of exposure. Both TLS and microtopographic profile gauges are used to obtain ground surface pro&#64257;les, from which Ex is estimated after the threshold distance (TD) is determined, i.e., the distance between the root and the sediment knickpoint, which allows de&#64257;ning the lowering of the ground surface caused by sheet erosion. For each profile, we measured the height between the topside of the root and a virtual plane tangential to the ground surface. In this way, we intended to avoid small-scale impacts of soil deformation, which may be due to pressures exerted by the root system, or by the arrangement of exposed roots. This may provoke small amounts of soil sedimentation or erosion depending on how they physically affect the surface runoff. We demonstrate that an adequate microtopographic characterization of exposed roots and their associated ground surface is very valuable to obtain accurate erosion rates. This finding could be utilized to develop the best management practices designed to eventually halt or perhaps, at least, lessen soil erosion, so that more sustainable management policies can be put into practice.

Characterizing erosion from dendrogeomorphology has usually focused on accurately finding the starting time of root exposure, by examining macroscopic or cell level changes caused by exposure. Here, we offer a detailed description of different novel techniques to obtain more precise erosion rates from highly accurate microtopographic data.

Laboratoire et au champ protocole pour estimer les taux d’érosion de feuille de Dendrogeomorphology

Sheet erosion is among the crucial drivers of soil degradation. Erosion is controlled by environmental factors and human activities, which often lead to ...