Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare

Patogeenit ovat haitallisia eliöitä, jotka tarvitsevat isäntää saadakseen tarvittavia ravinteita. Patogeenin haitallisuutta kutsutaan virulenssiksi, ja se on tärkeä osuus patogeeni-isäntä–suhteessa. Virulenssia säädellään tarkasti, sillä liian korkea virulenssi tappaa isännän liian nopeasti, jolloin...

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Päätekijä: Hämäläinen, Dorrit
Muut tekijät: Matemaattis-luonnontieteellinen tiedekunta, Faculty of Sciences, Bio- ja ympäristötieteiden laitos, Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylän yliopisto
Aineistotyyppi: Pro gradu
Kieli:eng
Julkaistu: 2016
Aiheet:
Linkit: https://jyx.jyu.fi/handle/123456789/53102
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author Hämäläinen, Dorrit
author2 Matemaattis-luonnontieteellinen tiedekunta Faculty of Sciences Bio- ja ympäristötieteiden laitos Department of Biological and Environmental Science University of Jyväskylä Jyväskylän yliopisto
author_facet Hämäläinen, Dorrit Matemaattis-luonnontieteellinen tiedekunta Faculty of Sciences Bio- ja ympäristötieteiden laitos Department of Biological and Environmental Science University of Jyväskylä Jyväskylän yliopisto Hämäläinen, Dorrit Matemaattis-luonnontieteellinen tiedekunta Faculty of Sciences Bio- ja ympäristötieteiden laitos Department of Biological and Environmental Science University of Jyväskylä Jyväskylän yliopisto
author_sort Hämäläinen, Dorrit
datasource_str_mv jyx
description Patogeenit ovat haitallisia eliöitä, jotka tarvitsevat isäntää saadakseen tarvittavia ravinteita. Patogeenin haitallisuutta kutsutaan virulenssiksi, ja se on tärkeä osuus patogeeni-isäntä–suhteessa. Virulenssia säädellään tarkasti, sillä liian korkea virulenssi tappaa isännän liian nopeasti, jolloin patogeeni ei ehti levitä uuteen isäntään. Liian matala virulenssi voi estää patogeenia tartuttamasta isäntää. Kilpailu muiden lajien tai kantojen kanssa voi vaikuttaa patogeenin virulenssiin, kuten myös ympäristötekijät. Flavobacterium columnare on kaloille kolumnaaritautia aiheuttava patogeenibakteeri. Kolumnaari tautia esiintyy kalankasvattamoilla ympäri maailmaa ja monella eri kalalajilla, ja aiheuttaa miljoonien edestä vahinkoja. Tauti on kasvava ongelma, sillä kalankasvattamoiden olosuhteiden uskotaan lisäävän patogeenien haitallisuutta, ja koska patogeeni on saprofyytti voi se elää kuolleessa kudoksessa, mikä vaikeuttaa taudin hoitamista. Tämän tutkielman tavoitteena oli selvittää, vaikuttaako ravintotaso kahden eri virulenssitasoisen F. columnare -kannan väliseen kilpailuun. Kahta F. columnare -kantaa kasvatettiin erikseen korkeassa ja matalassa ravintotasossa 35 päivän ajan, sekä kantojen 1:1 sekoituksena. Toisella kannoista on aiempien kokeiden mukaan korkea virulenssi, ja toisella kannalla matala virulenssitaso. Kantojen geneettistä erilaisuutta käytettiin hyväksi kantojen suhteen selvittämiseksi yhteiskasvatuksissa käyttäen qPCR:ää (kvantitatiivinen PCR). Tämän työn tuloksena oli että kaikki käsittelyt kasvoivat yhtä hyvin, ja vain lyhytaikaisia eroja kasvutrendeissä havaittiin. Yhteiskasvatuksissa qPCR-tulokset osoittivat virulentin kannan hallitsevan kasvatusta kummallakin ravintotasolla, ja osuudet olivat hyvin samanlaisia eri ravintotasoilla. Kantojen virulenssi testattiin kalakokeella sekä kasvatuskokeessa olleista bakteereista, että kasvatuskokeiden alkuperäisistä bakteerinäytteistä. Kirjolohenpoikasia altistettiin patogeeneille, ja taudin puhkeamista sekä sen aiheuttamia oireita seurattiin tunnin välein. Kasvatuksissa ollut virulentti kanta, sen alkuperäinen näyte ja kaikki kilpailukasvatukset olivat yhtä virulentteja, oletettavasti johtuen virulentin kannan hallitsevuudesta yhteiskasvatuksessa ravintotasosta riippumatta. Vähemmän virulentilla kannalla ravintotaso vaikutti virulenssiin, sillä alhaisessa ravintotasossa kasvaneella käsittelyllä oli matalampi virulenssitaso kuin korkeassa ravintotasossa kasvaneella sekä alkuperäisellä kannalla. Monessa kokeessa osoitettu kasvavan virulenssin trendi matalassa ja korkeassa ravintopitoisuudessa ei toteutunut tässä työssä. Sen sijaan kilpailukokeen tulos virulentin kannan hallitsevuudesta vastaa muiden tuloksia. Ravintotason vaikutusta virulenssiin ei luultavasti nähty tässä työssä bakteerien kasvatustavan vuoksi, ja kilpailuun vaikutti todennäköisesti virulentin kannan kyky inhiboida vähemmän virulentin kannan kasvua. Pathogens are harm-causing organisms that use a host for nutrients in order to be able to reproduce. How much harm a pathogen can cause a host or other organism, is called virulence. Virulence is an important factor in the host-pathogen relationship, and in theory it is regulated by the pathogen. Too high virulence kills the host before the pathogen can transmit to a new one, while too low virulence will hinder infection. Competition between pathogens and other species or strains can affect the virulence of the pathogen, and so can environmental conditions. Flavobacterium columnare is a bacterial fish pathogen, that causes columnaris disease. The disease is prevalent at fish farms around the world, where the disease kills fish worth millions yearly. The disease is a growing concern, with the conditions of the fish farms suggested to cause higher virulence, and because the pathogen can survive in dead tissue, treating the disease is complicated. The aim of this thesis was to see if the competitive outcome of two strains of F. columnare with different virulence levels differ when cultivated at different nutrient levels. Two strains of F. columnare were cultivated at a high nutrient level and a low nutrient level for 35 days, both separately and together as a 1:1 mix. One strain was considered highly virulent, and the other strain had a low level of virulence. Utilizing genetic differences of the strains, qPCR (quantitative PCR) was used to determine the relative proportions of the strains in mixed treatments. My results were that all treatments grew equally well, and only short-term differences in growth were found. In the mixed treatments qPCR testing showed that the virulent strain was dominant at both nutrient levels, and the proportions of strains were similar for both nutrient levels. For virulence tests, rainbow trout fingerlings were exposed to the pathogens, and the duration from exposure to fully developed disease was measured. The virulence of the strains were tested from pre-treatment and post-treatment samples. All treatments with the virulent strain and mixed strains were equally virulent, probably because the mixed cultures mostly consisted of the virulent strain. For the less virulent strain the low nutrient treatment had a lower virulence compared to the pre-treatment and high nutrient strains. My results did not conform to the expectations that virulence of F. columnare increases in high and low nutrient environments as is seen in many other studies. It does support the the theory that for F. columnare a strain with higher virulence will outcompete a strain with lower virulence. The true effect of nutrient level differences was possibly not achieved with this batch culture setup, and competition was probably influenced by the virulent strain inhibiting the growth of the less virulent strain.
first_indexed 2023-03-22T09:59:19Z
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Patogeenin haitallisuutta kutsutaan virulenssiksi, ja se on t\u00e4rke\u00e4 osuus patogeeni-is\u00e4nt\u00e4\u2013suhteessa. Virulenssia s\u00e4\u00e4dell\u00e4\u00e4n tarkasti, sill\u00e4 liian korkea virulenssi tappaa is\u00e4nn\u00e4n liian nopeasti, jolloin patogeeni ei ehti levit\u00e4 uuteen is\u00e4nt\u00e4\u00e4n. Liian matala virulenssi voi est\u00e4\u00e4 patogeenia tartuttamasta is\u00e4nt\u00e4\u00e4. Kilpailu muiden lajien tai kantojen kanssa voi vaikuttaa patogeenin virulenssiin, kuten my\u00f6s ymp\u00e4rist\u00f6tekij\u00e4t. Flavobacterium columnare on kaloille kolumnaaritautia aiheuttava patogeenibakteeri. Kolumnaari tautia esiintyy kalankasvattamoilla ymp\u00e4ri maailmaa ja monella eri kalalajilla, ja aiheuttaa miljoonien edest\u00e4 vahinkoja. Tauti on kasvava ongelma, sill\u00e4 kalankasvattamoiden olosuhteiden uskotaan lis\u00e4\u00e4v\u00e4n patogeenien haitallisuutta, ja koska patogeeni on saprofyytti voi se el\u00e4\u00e4 kuolleessa kudoksessa, mik\u00e4 vaikeuttaa taudin hoitamista. T\u00e4m\u00e4n tutkielman tavoitteena oli selvitt\u00e4\u00e4, vaikuttaako ravintotaso kahden eri virulenssitasoisen F. columnare -kannan v\u00e4liseen kilpailuun. Kahta F. columnare -kantaa kasvatettiin erikseen korkeassa ja matalassa ravintotasossa 35 p\u00e4iv\u00e4n ajan, sek\u00e4 kantojen 1:1 sekoituksena. Toisella kannoista on aiempien kokeiden mukaan korkea virulenssi, ja toisella kannalla matala virulenssitaso. Kantojen geneettist\u00e4 erilaisuutta k\u00e4ytettiin hyv\u00e4ksi kantojen suhteen selvitt\u00e4miseksi yhteiskasvatuksissa k\u00e4ytt\u00e4en qPCR:\u00e4\u00e4 (kvantitatiivinen PCR). 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V\u00e4hemm\u00e4n virulentilla kannalla ravintotaso vaikutti virulenssiin, sill\u00e4 alhaisessa ravintotasossa kasvaneella k\u00e4sittelyll\u00e4 oli matalampi virulenssitaso kuin korkeassa ravintotasossa kasvaneella sek\u00e4 alkuper\u00e4isell\u00e4 kannalla. Monessa kokeessa osoitettu kasvavan virulenssin trendi matalassa ja korkeassa ravintopitoisuudessa ei toteutunut t\u00e4ss\u00e4 ty\u00f6ss\u00e4. Sen sijaan kilpailukokeen tulos virulentin kannan hallitsevuudesta vastaa muiden tuloksia. Ravintotason vaikutusta virulenssiin ei luultavasti n\u00e4hty t\u00e4ss\u00e4 ty\u00f6ss\u00e4 bakteerien kasvatustavan vuoksi, ja kilpailuun vaikutti todenn\u00e4k\u00f6isesti virulentin kannan kyky inhiboida v\u00e4hemm\u00e4n virulentin kannan kasvua.", "language": "fi", "element": "description", "qualifier": "abstract", "schema": "dc"}, {"key": "dc.description.abstract", "value": "Pathogens are harm-causing organisms that use a host for nutrients in order to be able to reproduce. 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The aim of this thesis was to see if the competitive outcome of two strains of F. columnare with different virulence levels differ when cultivated at different nutrient levels. Two strains of F. columnare were cultivated at a high nutrient level and a low nutrient level for 35 days, both separately and together as a 1:1 mix. One strain was considered highly virulent, and the other strain had a low level of virulence. Utilizing genetic differences of the strains, qPCR (quantitative PCR) was used to determine the relative proportions of the strains in mixed treatments. My results were that all treatments grew equally well, and only short-term differences in growth were found. In the mixed treatments qPCR testing showed that the virulent strain was dominant at both nutrient levels, and the proportions of strains were similar for both nutrient levels. For virulence tests, rainbow trout fingerlings were exposed to the pathogens, and the duration from exposure to fully developed disease was measured. The virulence of the strains were tested from pre-treatment and post-treatment samples. All treatments with the virulent strain and mixed strains were equally virulent, probably because the mixed cultures mostly consisted of the virulent strain. For the less virulent strain the low nutrient treatment had a lower virulence compared to the pre-treatment and high nutrient strains. My results did not conform to the expectations that virulence of F. columnare increases in high and low nutrient environments as is seen in many other studies. It does support the the theory that for F. columnare a strain with higher virulence will outcompete a strain with lower virulence. 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spellingShingle Hämäläinen, Dorrit Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare columnaris disease Akvaattiset tieteet Aquatic sciences 4012 virulenssi taudinaiheuttajat kalat ravinto kalanviljely
title Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
title_full Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
title_fullStr Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
title_full_unstemmed Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
title_short Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
title_sort effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen flavobacterium columnare
title_txtP Effect of nutrients on competition between a virulent and a less virulent strain of the fish pathogen Flavobacterium columnare
topic columnaris disease Akvaattiset tieteet Aquatic sciences 4012 virulenssi taudinaiheuttajat kalat ravinto kalanviljely
topic_facet 4012 Akvaattiset tieteet Aquatic sciences columnaris disease kalanviljely kalat ravinto taudinaiheuttajat virulenssi
url https://jyx.jyu.fi/handle/123456789/53102 http://www.urn.fi/URN:NBN:fi:jyu-201702241519
work_keys_str_mv AT hämäläinendorrit effectofnutrientsoncompetitionbetweenavirulentandalessvirulentstrainofthefishpa