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.

ניסוי מעבדה .1 <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> השג את דגי הטרף להיות מוזן לדגים טורפים במהלך הניסוי. רצוי צריך להיות בשבי דג הטרף האלה בתחום, הקפוא, ומאוחסן בכ -30 C °. קחו למשל את פעילות דיג מסחרית כמקור פוטנציאלי לדגי הטרף. </li><li style=";text-align:right;direction:rtl"> להציג את דג הטורף למכלי המעבדה שישמש לניסוי. עד 15 דגי טורף הוכנס לתוך כל אחד מטנקי 870-L, ועד 30 דגי טורף הוכנס לתוך כל אחד מטנקי 2,380-L במחקרים קודמים 16,18. </li><li style=";text-align:right;direction:rtl"> להסתגל דג הטורף לדיאטה של ​​דגי טרף שנבחרו. ברגע שהתאקלם, דגי הטורף צריכים להישאר על דיאטה זו ל1-3 חודשים לפני תחילת הניסוי. </li><li style=";text-align:right;direction:rtl"> מניח בצד דגימות של דגי טרף על ידי באופן אקראי בחירת 10 עד 20 דגימות מרוכבים מהקבוצה של דגי טרף. מספר דגי טרף במדגם מרוכבים יכול נע בין 3 עד 100, תלוי בגודל של הטרףדגים. כל דגימה מרוכבים צריכה להיות כפולה בשקית, קפוא, ומאוחסן בכ -30 C °. </li><li style=";text-align:right;direction:rtl"> ליזום הניסוי על ידי הקרבת 30 עד 50% מהדגים בכל אחד מהטנקים. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> להרדים את הדגים, לערבב 8 גרם של Finquel עם 45 ליטר של מים במכל פלסטיק גדול ולאחר מכן למקם את הדג במכל עם פתרון Finquel. </li><li style=";text-align:right;direction:rtl"> מורדמים פעם, למקם את כל הדגים הקריבו מטנק אחד לשקית, שקית לאחר מכן לחצו פעמיים, וחנות בכ -30 ° C עד הזמן של העיבוד. </li><li style=";text-align:right;direction:rtl"> לשקול כל אחד מהדגים שנותרו בכל אחד מהטנקים, ולהקליט את המשקולות; הרדמה סבירה להניח שתהיה צורך לנהל במשקל. </li><li style=";text-align:right;direction:rtl"> כדי להרדים את הדגים, לערבב 4.6 גרם של Finquel עם 45 ליטר של מים במכל פלסטיק גדול, ולאחר מכן למקם את הדג במכל עם פתרון Finquel. </li><li style=";text-align:right;direction:rtl"> חכה כמה דקות עד שחומר ההרדמה תיכנס לתוקף לפני שקילת הדגים. </li></ol></li><li style=";text-align:right;direction:rtl"> בכל יום של הניסוי, להפשירכמות המתאימה של דגי טרף, ולחתוך את דגי טרף לחתיכות במשקל של כ 1 עד 5 גרם. לשקול את כמות דגי טרף כדי להיות ממוקם בכל אחד מהטנקים, ולאחר מכן שחרר את חתיכות דג טרף לכל טנק ולאפשר לדגים טורפים על 1 שעות כדי להאכיל. ואז להסיר את כל מזון שלא נאכל, לאפשר מזון לייבוש באוויר במשך כ20 דקות, ולאחר מכן לשקול את המזון שלא נאכל לכל אחד מהטנקים. רשום את כמות המזון ממוקמת בטנק ואת כמות מזון שלא נאכל לכל אחד מהטנקים בכל יום. הערה: לניסוי הנציג, טרוטה הואכלו כמזון ממש כמו שהיה לצרוך בתקופה אחת האכלה בכל יום 18. עם זאת, הדגים טורפים יכולים גם להיות ממוקמים במנות קבועות 16,19. </li><li style=";text-align:right;direction:rtl"> לסיים את הניסוי על ידי הקרבת כל הדגים טורפים שנותרו בכל אחד מהטנקים. להרדים את הדגים, לערבב 8 גרם של Finquel עם 45 ליטר של מים במכל פלסטיק גדול ולאחר מכן למקם את הדג במכל עם פתרון Finquel. הרשומה tהוא המשקל של כל אחד מהדגים הקריבו. לקבלת תוצאות אמינות, הניסוי חייב לרוץ ל100 ימים לפחות, רצוי לפחות 130 ימים. מניחים את כל הדגים מטנק לתוך תיק אחד, תיק לאחר מכן כפול, וחנות בכ -30 ° C עד מועד עיבוד. </li></ol> Homogenization 2 דגים <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> בחר קבוצה של דגים טורפים ו / או חומרים מרוכבים דגי טרף להפשרה. לאפשר מרוכבים להפשיר באופן חלקי. כל מרוכבים עשויים לדרוש 0.5-1 שעה לhomogenize. </li><li style=";text-align:right;direction:rtl"> באמצעות הבלנדרים המתאימים בגודל, homogenize כל אחד מהחומרים מרוכבים. עבור כל מרוכבים, למקם מדגם (50-100 ז) לhomogenate לתוך צנצנת ניקתה, ושטף אצטון, וכותרתו. לאחר מכן מכסה את הצנצנת ולאחסן את הצנצנת בכ -30 ° C עד למועד העיבוד. </li><li style=";text-align:right;direction:rtl"> לשטוף את כל הציוד המשמש לhomogenize הדגים, ולאחר מכן לשטוף היטב במים מזוקקים ומתנול, בין דגימות. </li></ol> .3 הפקה <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> שוקל 20.0 גרםשל מופשר רקמות דג הומוגני בכוס 200 מ&quot;ל. </li><li style=";text-align:right;direction:rtl"> להוסיף כ 40 גרם של נתרן גופרתי ומערבבים היטב עם מרית. </li><li style=";text-align:right;direction:rtl"> הוסף פתרון ספייק פונדקאית המכיל קרוב ב30, 61, 161, ו166. ספייק בריכוז כי תשואות ריכוז סופי של 20 / מ&quot;ל ​​ng בתמצית. </li><li style=";text-align:right;direction:rtl"> לאפשר המדגם להתייבש על RT תוך כדי ערבוב כל 20 דקות. </li><li style=";text-align:right;direction:rtl"> לאפשר את המדגם כדי להגיע עקביות של חול יבש, ובנקודה המדגם מוכן להפקה. </li><li style=";text-align:right;direction:rtl"> להגדיר את מנגנון חילוץ Soxhlet עם בקבוק 500 מ&quot;ל מכיל שבבי רתיחה טפלון, Soxhlet, וקבל. </li><li style=";text-align:right;direction:rtl"> מוסיף את תערובת דגים המיובש לאצבעון זכוכית עם תחתית דיסק-fritted גס או אצבעון נייר. </li><li style=";text-align:right;direction:rtl"> הוסף 150 מ&quot;ל של הקסאן 50% וdichloromethane 50% לכוס המשמשת למדגם ומערבבים תוך גירוד הקירות של הכוס עם מרית. </li><li style=";text-align:right;direction:rtl"> העבר את הממס לחלק העליון של Soxhlet עם הבקבוק המצורף ולאפשר לו לעבור בין Soxhlet וב<html> לבקבוק. </li><li style=";text-align:right;direction:rtl"> חוזר בשנית עם 150 מ&quot;ל שוב. </li><li style=";text-align:right;direction:rtl"> הנח את Soxhlet עם הבקבוק המצורף אל גוף החימום ולצרף את הקבל. </li><li style=";text-align:right;direction:rtl"> הפעל את גוף החימום ולהביא הממס לרתיחה עדינה, ואז לחלץ למינימום של 16 שעות כדי לוודא שמים קרים מסופקים למעבים. </li><li style=";text-align:right;direction:rtl"> לאחר שאפשר הממס להתקרר, לבדוק אם כל אחד מצלוחיות המדגם מכיל מים. עבור אלה צלוחיות המכילות מים, להוסיף נתרן גופרתי ולערבל עד שהמים נספגים על ידי נתרן גופרתי. </li><li style=";text-align:right;direction:rtl"> לרכז את המדגם באמצעות concentrator מדגם חנקן או התקנת Kaderna הדני (KD) כלי זכוכית עם אמבט מים חם. </li><li style=";text-align:right;direction:rtl"> לאפשר המדגם להתאדות בהיקף של פחות מ 2 מ&quot;ל, ולאחר מכן להביא לנפח סופי של 5 מ&quot;ל באמצעות כביסות קטנות של הקסאן להעביר את הדגימה מכלי הזכוכית המשמשות לבקבוק מדידה 5 מ&quot;ל. </li><li style=";text-align:right;direction:rtl"> העברה ל10 מ&quot;ל בקבוקון ותווית עם מידע מדגם. </li></ol>s = &quot;jove_title&quot;&gt; 4. לחלץ נקי-up <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> הכן סיליקה ג&#39;ל acidified ידי הוספת 44 גרם של חומצה גופרתית המרוכזת לשל סיליקה ג&#39;ל מופעל 100 גרם. </li><li style=";text-align:right;direction:rtl"> הוסף 10 גרם של סיליקה ג&#39;ל acidified לעמודת כרומטוגרפיה קטנה המכילה התוספת קטנה של צמר זכוכית בתחתית. </li><li style=";text-align:right;direction:rtl"> הוסף 1 מ&quot;ל של תמצית מדגם לעמודה לאחר שלפני ניקוי העמודה עם 10 מ&quot;ל של הקסאן. </li><li style=";text-align:right;direction:rtl"> Elute העמודה עם 20 מ&quot;ל של הקסאן ולאסוף בשפופרת זכוכית 20 מ&quot;ל מחודדת. </li><li style=";text-align:right;direction:rtl"> מניחים את צינור הזכוכית על מכשיר מאייד חנקן (N-Vap) תחת זרם של חנקן ושקוע במים חמים. </li><li style=";text-align:right;direction:rtl"> להתאדות פחות מ 1 מ&quot;ל אבל לא ליובש. </li><li style=";text-align:right;direction:rtl"> מוציאים ממנגנון N-Vap ולהעביר לבקבוק המדידה 1 מ&quot;ל עם כביסות קטנות של הקסאן. </li><li style=";text-align:right;direction:rtl"> העברה ל1.8 מ&quot;ל autosampler בקבוקון שכותרתו עם מידע מדגם. </li><li style=";text-align:right;direction:rtl"> ספייק 4 μl לסטנדרטים פנימיים לתוך הבקבוקון. המדגם הוא מוכן לניתוח עכשיו. </li></ol> .5 אנאלייסיס על ידי גז כרומטוגרפיה - ספקטרומטריית מסת השימוש שלילי כימי יינון <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> השתמש בסטנדרטים לכייל את המכשיר: הסטנדרטים זמינים בתערובות מורכבות מקבוצות של קרובים במופרד היטב. תערובות 1-5 כוללות כמעט את כל הקרובים במצא ב -1016 Arochlors, 1221, 1232 1242, 1248, 1,254, ו1260. מערבבים 1 משמש כתערובת כיול רב ברמה, וליניאריות מערכת אושר על ידי הכנה לפחות חמש רמות כיול בריכוזים בין 2 ל 100 ng / ml. תערובות 2-5 משמשות ככיולי נקודה אחת עבור כל משלימתו. </li><li style=";text-align:right;direction:rtl"> הגדרת כרומטוגרפיה - מערכת ספקטרומטריית מסה במצב היינון הכימי השלילי עם מימן כגז המוביל (1 מ&quot;ל / דקה) ומתאן כגז מגיב. </li><li style=";text-align:right;direction:rtl"> השתמש התמזגה סיליקה, טור נימים (60 מ &#39;× 0.25 מ&quot;מ הקוטר פנימי) מצופה בDB-XLB בעובי סרט 0.25-מיקרומטר להפרדה. טמפרטורת תכנית תנור 60-212 ° C 25 מעלות צלזיוס / דקה, ולאחר מכן ל260 ° C ב1 ° C / min, ולאחר מכן ל280 ° C ב 4 ° C / דקה, עם זמן את האחיזה סופית של 4 דקות. יש להגדיר טמפרטורות מזרק וקו ההעברה ב280 ° C. הזרק 1 עד 2 μl של המדגם באמצעות מצב זריקת splitless. </li><li style=";text-align:right;direction:rtl"> לנתח את כל הסטנדרטים ודגימות בשיטה סטנדרטית הפנימית באמצעות 13 decachlorobiphenyl שכותרתו C. </li><li style=";text-align:right;direction:rtl"> לבצע בדיקה על הכיול הראשוני על ידי הפעלה סטנדרטי מקור שני וAroclors 1,242 ו1260, ולאחר מכן להשוות ערכים חזויים לקרובים בAroclor עם הסכומים שנצפו מהליך בדיקה זו. </li><li style=";text-align:right;direction:rtl"> ברגע שהליך הכיול הראשוני הושג בהצלחה ניתוח מלא, של כל הדגימות. הפעל כיול לבדוק כל עשר דגימות, באמצעות כל אחד מתערובות הכיול מהכיול הראשוני. </li></ol> .6 חישוב העברה יעיל הנקי הטרופית <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> לחשב את יעילות העברה תזונתית נטו, γ, עבור כל שילוב oטנק f ומשלימתו PCB באמצעות המשוואה הבאה: <img alt="משוואת 1" fo:content-width="2in" src="/files/ftp_upload/51496/51496eq1.jpg" /> , שבו [f PCB] היא ריכוז משלימתו PCB הממוצע של דג הטורף במכל בסוף הניסוי, f W היא המשקל הממוצע של הדגים טורפים במכל בסוף הניסוי, [PCB i] הוא ריכוז משלימתו PCB הממוצע של דג הטורף במכל בתחילת הניסוי, W הוא i המשקל הממוצע של הדגים טורפים בתחילת הניסוי, ואת כמות משלימתו PCB בלע מתייחסת למשקל של משלימתו PCB בליעה, בממוצע, על ידי כל אחד טרוטה בטנק במהלך הניסוי. </li><li style=";text-align:right;direction:rtl"> לחשב את המכנה במשוואה לעיל על ידי הכפלת הריכוז הממוצע של משלימתו PCB בחומרים מרוכבים דגי טרף על ידי הכמות הממוצעת (במשקל) של דגי הטרף אכל לדגים טורפים בdur הטנקing את כל מהלך הניסוי. </li></ol>

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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>

עבור האומדנים מדויקים ביותר של γ, הנסיין חייב להיות מסוגל לעקוב אחר שתי כמות המזון ממוקמת בכל אחד מהטנקים וכמות מזון שלא נאכל בכל אחד מהטנקים במהלך הניסוי בצורה מדויקת. כדי להשיג זאת, הנסיין חייב להיות מסוגל להסיר את כל מזון שלא נאכל מהטנקים ולקבוע במדויק את משקלו. בנ?...

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.

<table border="0" cellpadding="0" cellspacing="0" width="632">
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			<td height="21" style="height:21px;width:259px;">Name&#160;</td>
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			<td style="width:119px;">Catalog Number</td>
			<td style="width:167px;">Comments</td>
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			<td style="width:119px;">RT-430-1</td>
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			<td style="width:87px;">Burdick &#38; Jackson&#160;</td>
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			<td style="width:87px;">Burdick &#38; Jackson&#160;</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 style="width:87px;">Agilent</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 style="width:87px;">Agilent/ J&#38;W</td>
			<td style="width:119px;">122-1262</td>
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</table>

laboratory estimation of net trophic transfer efficiencies of pcb congeners to lake trout (salvelinus namaycush) from its prey

טכניקה להערכת מעבדה של יעילות נטו תזונתית העברה (γ) של biphenyl polychlorinated קרוב ב( PCB) לדגי piscivorous מהטרף שלהם מתוארת במסמך זה. במהלך ניסוי מעבדה 135 יום, האכלנו מנופח (Coregonus hoyi) שנתפס באגם מישיגן לטרוטה (namaycush Salvelinus) המשיך בשמונה טנקי מעבדה. המנופח הוא טרף טבעי עבור טרוטה. בארבעת הטנקים, קצב זרימה גבוה יחסית היה בשימוש על מנת להבטיח פעילות גבוהה יחסית על ידי טרוטה, ואילו קצב זרימה נמוך שימש בארבעה טנקים האחרים, המאפשר לפעילות טרוטה נמוכה. על בסיס טנק אחר טנק, כמות המזון נאכלה על ידי טרוטה בכל יום של הניסוי נרשמה. כל טרוטה נשקלה בהתחלה והסיום של הניסוי. ארבעה עד תשע טרוטה מכל אחד משמונת הטנקים הוקרבו בתחילת הניסוי, וכל פורל 10 האגם שנותר בכל אחד מהטנקים היו euthanized בסוף הניסוי. אנחנו נקבע ריכוזים של 75 קרובים בPCB בטרוטה בתחילת הניסוי, בטרוטה בסוף הניסוי, ובbloaters מוזנים לטרוטה במהלך הניסוי. בהתבסס על המדידות הללו, γ חושב שלכל אחד מן 75 קרובים בPCB בכל אחד משמונת הטנקים. אומר γ חושב שלכל אחד מן קרוב בPCB 75 לטרוטה שני פעילה ולא פעילה. בגלל הניסוי חזר על עצמו בשמונה טנקים, השגיאה סטנדרטית על משמעות γ יכול להיות מוערך. תוצאות מסוג זה של ניסוי שימושיות במודלים להערכת סיכון ללחזות את עתיד סיכון לבני אדם וחיות בר אכילת דגים מזוהמים בתרחישים שונים של זיהום סביבתי.

טרוטה הראתה כמות משמעותית של צמיחה במהלך הניסוי, כטרוטה הראשונית אומרת משקולות נעות 694-907 g כאשר טרוטה הסופית אומרת משקולות נעות בין 853 ל1,566 גר &#39;(טבלת 1). כמות המזון הממוצעת הנצרכת על ידי טרוטה במהלך הניסוי 135 היום נעה בין 641 ל2,649 גרם. אומר ריכוזי משלימתו PCB בטרוט...

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

טכניקה להערכת מעבדה של יעילות נטו תזונתית העברת biphenyl polychlorinated הקרוב ב( PCB) לדגי piscivorous מהטרף שלהם מוצגת. על מנת למקסם את תחולתה של תוצאות המעבדה לשדה, דגי piscivorous צריכים להיות מוזנים דגי טרף שנאכלים בדרך כלל בתחום.

הערכת מעבדה של יעילות העברה הנקי התזונתית של קרוב בPCB לאגם פורל (<em&gt; Salvelinus namaycush</em&gt;) מטרפו

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

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Environment

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

10.9K Views.  U. S. Geological Survey.  טכניקה להערכת מעבדה של יעילות נטו תזונתית העברת biphenyl polychlorinated הקרוב ב( PCB) לדגי piscivorous מהטרף שלהם מוצגת. על מנת למקסם את תחולתה של תוצאות המעבדה לשדה, דגי piscivorous צריכים להיות מוזנים דגי טרף שנאכלים בדרך כלל בתחום. 

Video: 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.

נקבע מעבדה זרחן שטף מאגם המשקעים כמדד לטעינה הפנימית זרחן

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

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.

מעבדה מבדק-האכלת דגים לבחינת פעילות Antipredatory של משני מטבוליטים מהרקמות של אורגניזמים ימיים

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.

בחירת גודל האוטומטי ג&#39;ל כדי לשפר את האיכות של ספריות רצף הדור הבא הוכן מדגימות סביבתיות מים

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.

הסרת יסודות קורט ידי Cupric תחמוצת חלקיקים מאורניום<em&gt; באתר</em&gt; שחזור Bleed מים והשפעתה על כדאיויות תא

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.

סימולצית מעבדה של הברזל (II) -rich Precambrian ימי גאות מערכת לחקור את הצמיחה של חיידקים פוטוסינתטיים

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.

פיתוח של<em&gt; מטריציום anisopliae</em&gt; כמקוטלת חיידקים: מהבידוד לביצועי שדה

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.

תהליכי מעבדה ההדברה להדברה בגז תחמוצת החנקן

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.

דבקותה של חיידקים לשתול משטחים הנמדדים במעבדה

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.

המערכת האקולוגית פרוטוקולים פבריקציה נוספת (EcoFAB) להקמת מערכות אקולוגיות מעבדה שנועדה ללמוד אינטראקציות צמח-חיידק

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.

מעבדה ופרוטוקול שדה עבור הערכת גיליון שחיקת המחירים מ- Dendrogeomorphology

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