Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications
This thesis deals with the question of whether planktonic protits of the genus Dinophysis have permanent plastids (=chloroplasts) or practice kleptoplasty, i.e. acquire plastids via predation on other microorganisms. Sequencing the plastid 16S rDNA of Dinophysis spp. collected from 4 different geogr...
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Linnéuniversitetet, Institutionen för naturvetenskap, NV
2010
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ftlinnaeusuniv:oai:DiVA.org:lnu-144 2023-05-15T16:30:12+02:00 Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications Minnhagen, Susanna 2010 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-144 eng eng Linnéuniversitetet, Institutionen för naturvetenskap, NV Växjö, Kalmar Linnaeus University Dissertations 19 http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-144 urn:isbn:9789186491246 info:eu-repo/semantics/openAccess Dinophysis kleptoplastid real-time PCR 16S rRNA plastid evolution Baltic Sea Flow cytometry Ecology Ekologi Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2010 ftlinnaeusuniv 2023-01-25T23:32:55Z This thesis deals with the question of whether planktonic protits of the genus Dinophysis have permanent plastids (=chloroplasts) or practice kleptoplasty, i.e. acquire plastids via predation on other microorganisms. Sequencing the plastid 16S rDNA of Dinophysis spp. collected from 4 different geographical regions unveiled two different plastid genotypes within this genera: one that was found at all locations investigated, identical to that of the free-living cryptophyte Teleaulax amphioxeia, and another found only in the Greenland Sea, closely related to that of the cryptophyte Geminigera cryophila. Both types were found within the species D. acuminata. These findings imply that the plastids in Dinophysis spp. were not inherited from a common ancestor, but acquired from feeding. By using flow cytometry in combination with an acidotrophic probe, it was shown that 71 % of the cells in a D. norvegica population in the aphotic zone of the Baltic Sea had food-vacuoles. Dinophysis used to be regarded as a primarily phototrophic organism, and this was a higher proportion of cells with food-vacuoles than reported earlier. To further study if Dinophysis needs constant refill of new plastids from the environment, a new method combining flow-cytometry and quantitative real-time PCR was developed to compare the levels of nuclear and plastid DNA in different phases of the cell-cycle. Results showed that plastid acquisition in Dinophysis was uncoupled with the cell-cycle, which is different than the pattern seen in microalgal species with permanent plastids. Furthermore, when quantitative real-time PCR combined with flow-cytometry was used to follow D. caudata cultures during a 65 days starvation/feeding experiment, the cells first went through a steady decrease in plastid DNA during starvation. In contrast, after feeding on the ciliate Myrionecta rubra, plastid DNA in starved cells increased 7-fold, thereby directly revealing the kleptoplastic behavior. The main conclusion from this thesis is that Dinophysis cells are ... Doctoral or Postdoctoral Thesis Greenland Greenland Sea Linnaeus University Kalmar Växjö: Publications (DiVA) Greenland |
institution |
Open Polar |
collection |
Linnaeus University Kalmar Växjö: Publications (DiVA) |
op_collection_id |
ftlinnaeusuniv |
language |
English |
topic |
Dinophysis kleptoplastid real-time PCR 16S rRNA plastid evolution Baltic Sea Flow cytometry Ecology Ekologi |
spellingShingle |
Dinophysis kleptoplastid real-time PCR 16S rRNA plastid evolution Baltic Sea Flow cytometry Ecology Ekologi Minnhagen, Susanna Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
topic_facet |
Dinophysis kleptoplastid real-time PCR 16S rRNA plastid evolution Baltic Sea Flow cytometry Ecology Ekologi |
description |
This thesis deals with the question of whether planktonic protits of the genus Dinophysis have permanent plastids (=chloroplasts) or practice kleptoplasty, i.e. acquire plastids via predation on other microorganisms. Sequencing the plastid 16S rDNA of Dinophysis spp. collected from 4 different geographical regions unveiled two different plastid genotypes within this genera: one that was found at all locations investigated, identical to that of the free-living cryptophyte Teleaulax amphioxeia, and another found only in the Greenland Sea, closely related to that of the cryptophyte Geminigera cryophila. Both types were found within the species D. acuminata. These findings imply that the plastids in Dinophysis spp. were not inherited from a common ancestor, but acquired from feeding. By using flow cytometry in combination with an acidotrophic probe, it was shown that 71 % of the cells in a D. norvegica population in the aphotic zone of the Baltic Sea had food-vacuoles. Dinophysis used to be regarded as a primarily phototrophic organism, and this was a higher proportion of cells with food-vacuoles than reported earlier. To further study if Dinophysis needs constant refill of new plastids from the environment, a new method combining flow-cytometry and quantitative real-time PCR was developed to compare the levels of nuclear and plastid DNA in different phases of the cell-cycle. Results showed that plastid acquisition in Dinophysis was uncoupled with the cell-cycle, which is different than the pattern seen in microalgal species with permanent plastids. Furthermore, when quantitative real-time PCR combined with flow-cytometry was used to follow D. caudata cultures during a 65 days starvation/feeding experiment, the cells first went through a steady decrease in plastid DNA during starvation. In contrast, after feeding on the ciliate Myrionecta rubra, plastid DNA in starved cells increased 7-fold, thereby directly revealing the kleptoplastic behavior. The main conclusion from this thesis is that Dinophysis cells are ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Minnhagen, Susanna |
author_facet |
Minnhagen, Susanna |
author_sort |
Minnhagen, Susanna |
title |
Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
title_short |
Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
title_full |
Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
title_fullStr |
Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
title_full_unstemmed |
Kleptoplasty in Dinophysis spp : Ecological role and evolutionary implications |
title_sort |
kleptoplasty in dinophysis spp : ecological role and evolutionary implications |
publisher |
Linnéuniversitetet, Institutionen för naturvetenskap, NV |
publishDate |
2010 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-144 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Greenland Sea |
genre_facet |
Greenland Greenland Sea |
op_relation |
Linnaeus University Dissertations 19 http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-144 urn:isbn:9789186491246 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766019924009943040 |