Dr. Gianna Dirren
Limnological Station
University of Zürich
Seestrasse 187
CH-8802 Kilchberg
gianna.dirren@uzh.ch

phone:
+41 (0)44 63 49214
fax:
+41 (0)44 63 41225
Research Interests
Education
Fellowships and Awards
List of Publications

[ print version ]

Research Interests

I have been fascinated by the world of aquatic microorganisms since my first look through a microscope. My research is focussed on eukaryotic microorganisms, in particular on pelagic ciliates. Thereby, a special emphasis lies on the ecophysiology of ciliates: what they feed on, which are their main predators, when and why they bloom during the season, and finally how these protists will react on environmental changes (e.g., lake warming). To answer these questions, ciliates need to be identified and quantified in their natural environments at a high temporal and spatial resolution. Apart from the morphological approach, which is by microscopy, we investigate the diversity of ciliates in Lake Zurich also by molecular tools like high-throughput sequencing (HTS). By using a combination of both approaches, we intend to receive a holistic picture of ciliates, aquatic microorganisms in general, and their interactions in the pelagic realm of Lake Zurich.


Applied methods

Light microscopy; identification, isolation and cultivation of ciliates; quantitative and qualitative protargol staining (QPS); PCR of ciliate and algal cultures; illustrations of ciliates; general lake monitoring methods


Affiliated project

Lake warming and microbial food web dynamics in spring: a focus on ciliates (SNF project 31003A_182489)


Contribution to Conferences

DGP 2019, Poster

38th Meeting of the German Society for Protozoology (Wien, Austria, 2019)

Poster presentation: "Seasonality of planktonic freshwater ciliates: are analyses based on V9 regions of the 18S rRNA gene correlated with morphospecies counts?"

DGP 2018, Poster

37th Meeting of the German Society for Protozoology (Koeln, Germany, 2018)

Poster presentation: "Morphological and Molecular Based Analyses of Planktonic Ciliates in Lake Zurich"

SAME 2017, Talk

15th SAME, Symposium of Aquatic Microbial Ecology (Zagreb, Croatia, 2017)

Oral presentation: "The green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with its endosymbiotic algae (Micractinium sp.), living in traps of a carnivorous aquatic plant"

FBFW 2017, Poster

5th Meeting of Fresh Blood for Fresh Water (Česk? Budĕjovice, Czech Republic, 2017)

Poster presentation: "The green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with its endosymbiotic algae (Micractinium sp.), living in traps of a carnivorous aquatic plant"

DGP 2017, Poster

36th Meeting of the German Society for Protozoology (Meissen, Germany, 2017)

Poster presentation: "The green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with its endosymbiotic algae (Micractinium sp.), living in traps of a carnivorous aquatic plant"

DGP 2016, Poster

35th Meeting of the German Society for Protozoology (Saignelegier, Switzerland, 2016)

Poster presentation: "When a lake stops mixing: the fatal effects of lake warming on the protistan community"

ECOP 2015, Poster

7th European Congress of Protistology ECOP in partnership with ISOP (Sevilla, Spain, 2015)

Poster presentation: "When a lake stops mixing: the fatal effects of lake warming on the protistan community"


Education

2019 - present University of Zurich, Postdoc at the Limnological Station
2015 - 2019 University of Zurich, PhD in Ecology at the Limnological Station, supervised by Prof. Thomas Posch Title: "Ciliates in Freshwater Ecosystems: Insights from Morphological and Molecular Approaches"
2014 - 2015 University of Zurich, Master in Microbiology at the Limnological Station, supervised by Prof. Thomas Posch Title: "Morphological and molecular based analyses of planktonic ciliates in Lake Zurich"
2009 - 2014 University of Zurich, Bachelor of Science in Biology

Fellowships and Awards

2017 Poster prize (first place) at the conference of the German Society for Protozoology, Meissen (Germany)
2017 Poster prize (first place) at the conference of Fresh Blood for Fresh Water, Česk? Budĕjovice (Czech Republic)
2016 Poster prize (first place) at the conference of the German Society for Protozoology, Saignelegier (Switzerland)
2015 Master thesis awarded by the Foundation for Hydrobiology-Limnology (Hydrobiologie-Limnologie-Stiftung fuer Gewaesserforschung), Zurich

List of Publications

Dirren-Pitsch, G., Bühler, D., Salcher, M.M., Bassin, B., Le Moigne, A., Schuler, M., Pernthaler, J., and Posch, T. (2022). FISHing for ciliates: Catalyzed reporter deposition fluorescence in situ hybridization for the detection of planktonic freshwater ciliates. Frontiers in Microbiology 13. doi: 10.3389/fmicb.2022.1070232
Link

Frantal, D., Agatha, S., Beisser, D., Boenigk, J., Darienko, T., Dirren-Pitsch, G., Filker, S., Gruber, M., Kammerlander, B., Nachbaur, L., Scheffel, U., Stoeck, T., Qian, K., Weißenbacher, B., Pröschold, T. and Sonntag, B. (2022). Molecular Data Reveal a Cryptic Diversity in the Genus Urotricha (Alveolata, Ciliophora, Prostomatida), a Key Player in Freshwater Lakes, With Remarks on Morphology, Food Preferences, and Distribution. Frontiers in Microbiology 12. doi: 10.3389/fmicb.2021.787290
Link

Forster, D., Qu, Z., Pitsch, G., Bruni, E.P., Kammerlander, B., Pröschold, T., Sonntag, B., Posch, T., and Stoeck, T. (2021) Lake ecosystem robustness and resilience inferred from a climate-stressed protistan plankton network. Microorganisms 9(3):549.
Link

Pröschold, T., Rieser, D., Darienko, T., Nachbaur, L., Kammerlander, B., Qian, K., Pitsch, G., Bruni, E.P., Qu, Z., Forster, D., Rad-Menendez, C., Posch, T., Stoeck, T., and Sonntag, B. (2021). An integrative approach sheds new light onto the systematics and ecology of the widespread ciliate genus Coleps (Ciliophora, Prostomatea). Scientific Reports 11(1):5916. doi: 10.1038/s41598-021-84265-y
Link

Qu, Z., Forster, D., Bruni, E.P., Frantal, D., Kammerlander, B., Nachbaur, L., Pitsch, G., Posch, T., Pröschold, T., Teubner, K., Sonntag, B., and Stoeck, T. (2021). Aquatic food webs in deep temperate lakes: key species establish through their autecological versatility. Molecular Ecology 30(4):1053-1071
Link

Posch, T., Pitsch, G., and Bruni, E.P. (2020). Protists: Ciliates. In: Encyclopedia of Inland Waters, 2nd edition. Elsevier Inc.
Link

Pröschold, T., Pitsch, G., and Darienko, T. (2020). Micractinium tetrahymenae (Trebouxiophyceae, Chlorophyta), a New Endosymbiont Isolated from Ciliates. Diversity 12(5), 200.
Link

Pitsch, G., Bruni, E.P., Forster, D., Qu, Z., Sonntag, B., Stoeck, T., and Posch, T. (2019). Seasonality of Planktonic Freshwater Ciliates: Are Analyses Based on V9 Regions of the 18S rRNA Gene Correlated With Morphospecies Counts? Frontiers in Microbiology 10:248. doi: 10.3389/fmicb.2019.00248.
Link

Dirren, S., Pitsch, G., Silva, M.O.D., and Posch, T. (2017). Grazing of Nuclearia thermophila and Nuclearia delicatula (Nucleariidae, Opisthokonta) on the toxic cyanobacterium Planktothrix rubescens. Europ J Protistol, 60:87-101. doi:10.1016/j.ejop.2017.05.009
Link

Pitsch, G., Adamec, L., Dirren, S., Nitsche, F., Šimek, K., Sirová, D., and Posch, T. (2017). The Green Tetrahymena utriculariae n. sp. (Ciliophora, Oligohymenophorea) with its Endosymbiotic Algae (Micractinium sp.), Living in Traps of a Carnivorous Aquatic Plant. J Eukaryot Microbiol, 64:322-335. doi: 10.1111/jeu.12369.
Link

Šimek, K., Pitsch, G., Salcher, M.M., Sirová, D., Shabarová, T., Adamec, L., and Posch, T. (2017). Ecological Traits of the Algae-Bearing Tetrahymena utriculariae (Ciliophora) from Traps of the Aquatic Carnivorous Plant Utricularia reflexa. J. Eukaryot. Microbiol., 64:336-348. doi: 10.1111/jeu.12368.
Link

Posch, T., Eugster, B., Pomati, F., Pernthaler, J., Pitsch, G., and Eckert, E.M. (2015). Network of interactions between ciliates and phytoplankton during spring. Front. Microbiol.6: 1289. doi: 10.3389/fmicb.2015.01289
Link