Fungal and cyanobacterial gene expression in a lichen symbiosis: Acclimatization and adaptation to temperature and habitat

Arnar Pálsson, 29/08/2016

Sophie  S Steinhäuser, Ólafur S Andrésson, Arnar Pálsson, Silke Werth Fungal and cyanobacterial gene expression in a lichen symbiosis: Acclimatization and adaptation to temperature and habitat

Accepted in Fungal Biology.

The capacity of species to cope with variation in the physical environment, e.g. in temperatures and temperature fluctuations, can limit their spatial distribution. Organisms have evolved cellular mechanisms to deal with damaging effects of increased temperature and other aggravation, primarily through complex molecular mechanisms including protein refolding and DNA repair. It is of interest to see whether these responses vary with geographic location, with high vs. low elevation and on the coast vs. inland, indicating longterm acclimatization or genetic adaptation. As mutualistic symbioses, lichens offer the possibility of analyzing molecular stress responses in a particularly tight interspecific relationship. For this study, we have chosen the widespread cyanolichen Peltigera membranacea, a key player in carbon and nitrogen cycling in terrestrial ecosystems at northern latitudes. We ask whether increasing temperature is reflected in mRNA levels of selected damage control genes, and do the response patterns show geographical associations? Using real-time PCR quantification of 38 transcripts, differential expression was demonstrated for nine cyanobacterial and nine fungal stress response genes (plus the fungal symbiosis-related lec2 gene) when the temperature was increased from 5°C to15°C and 25°C. Principle component analysis (PCA) revealed two gene groups with different response patterns. Whereas a set of cyanobacterial DNA repair genes and the fungal lec2 (PC1 group) showed an expression drop at 15°C vs. 5°C, most fungal candidates (PC2 group) showed increased expression at 25°C vs. 5°C. PC1 responses also correlated with elevation. The correlated downregulation of lec2 and cyanobacterial DNA repair genes suggests a possible interplay between the symbionts warranting further studies.

(Icelandic) Hvernig kemst maður í framhaldsnám í líffræði?

Arnar Pálsson, 08/08/2016

Sorry, this entry is only available in Icelandic.

(Icelandic) Fjórðungi bregður til nafns: af uppnefndum genum og sérvisku erfðafræðinga

Arnar Pálsson, 03/08/2016

Sorry, this entry is only available in Icelandic.

Organizing a big lecture

Arnar Pálsson, 04/07/2016

When in college I discovered the joy of throwing decent party. Of late this has taken more respectable form, in us taking part in organizing various meetings, workshops and lectures. This winter I participated in a project unlike most other I had previously. Organizing Jane Goodall’s visit to Iceland, which culminated in her talk at the University theater on June 15th. There were more than 10 associations and institutes that put in hours, money and effort to bring Jane here, make arrangements, gather funds and handle publicity.

This was truly a delightful cooperation, and getting to meet the grandest of primatologists was a big honour. Jane took part in a master class for the graduates students at the University of Iceland, and few other international students here, and then gave a brilliant lecture to a full auditorium. Vigdis Finnbogadottir, the former president of Iceland introduced Jane.JaneSvid

It was a true honor to help out in this adventure, and to commemorate that I indulge by posting figure of Jane, Mary Lewis her right hand, and the organizers.

NCBio meeting on genetic modification of human embryos

Arnar Pálsson, 16/06/2016

Nordic committee on bioethics in junction with the Norwegian biotechnology board, organized a miniconference on the new Crispr/Cas technology and the genetic modification of human embryos. The conference was held at the University of Oslo, June 2nd. The title was Gene therapy and human germline editing: new opportunities, new challenges.

We heared great talks by Fredrick Lanner, Gunnar Kvalheim, Johanna Ahola-Launonen, Jacob Wang, Anne-Marie Gerdes and Nils-Eric Sahlin, and were then given the task to summarize the meeting.

I will not attempt to do that here, because my notes were incomplete and the things I said didnt quite follow the notes (either a plus or minus, Im not sure).

The new technologies open some new opportunities, for studying the effects of mutations and systems on human cells and early development. There is also the future possibility of using this technology to modify the human cells, to correct serious errors in DNA to treat (somatic) or to prevent (germline) devastating diseases. The current seems to be flowing in that direction, granting of course that the technology will become efficient enough and side effects can be minimized. In fact this is the first moment that I felt that steps towards germline could and perhaps should be taken.

To counter, there were several issues raised with further developing the technology for modifying human embryos, including the slippery-slope argument, side-effects, dont-mess-with-nature, and a few others. But in general they are no unique to this technology.

The only new concept is that we may alter the genetic makeup of our species directly with this new technology. But in fact we have been changing our genetic makeup, indirectly with choices in lifestyle and human history and technological development.

In sum, I learned a lot but am still confused about the subject.

Those who want to read more should check out a new statement and report by the Danish council on ethics which summarized these issues quite well.

Statement from the Danish Council on Ethics on genetic modification of future humans (2016)




Attended an EMBL meeting on studies of evolution and ecology

Arnar Pálsson, 30/05/2016

I enjoyed the great fortune of attending a meeting on new model systems to link ecology and evolution, held May 8. – 11. in Heidelberg. D. Tautz and D. Weigel organized the meeting which brought together people studying evolutionary and ecological questions, interleaving genetic, organismal, microbial and biochemical data from many organisms. The taxanomic richness was quite intriguing, but also the range of questions and findings. We presented results from the Arctic charr studies, both the morphometric analyses and the transcriptome work, and got quite a lot of good feedback and suggestions. All in all it was a very inspiring meeting, with great atmosphere, talks, people and food. It did not spoil things that I got to visit my friend Natalia and see some great looking starfish.

Im looking forward to the next EMBL meeting on this topic.

(Icelandic) Katrín Halldórsdóttir varði ritgerð sína

Arnar Pálsson, 30/05/2016

Sorry, this entry is only available in Icelandic.

Revised: The developmental transcriptome of contrasting Arctic charr (Salvelinus alpinus) morphs

Arnar Pálsson, 27/04/2016
Resubmission to F1000research. The developmental transcriptome of contrasting Arctic charr (Salvelinus alpinus) morphs [version 2; referees: 2 approved with reservations]
Johannes Gudbrandsson1Ehsan P. Ahi1Sigridur R. Franzdottir1Kalina H. Kapralova1Bjarni K. Kristjansson2S. Sophie Steinhaeuser1Valerie H. Maier1Isak M. Johannesson1Sigurdur S. Snorrason1Zophonias O. Jonsson1Arnar Palsson1

Species and populations with parallel evolution of specific traits can help illuminate how predictable adaptations and divergence are at the molecular and developmental level. Following the last glacial period, dwarfism and specialized bottom feeding morphology evolved rapidly in several landlocked Arctic charr Salvelinus alpinus populations in Iceland.
Continue reading 'Revised: The developmental transcriptome of contrasting Arctic charr (Salvelinus alpinus) morphs'»

(Icelandic) Leyndardómar gena, baktería og uppruna lífs

Arnar Pálsson, 22/04/2016

Sorry, this entry is only available in Icelandic.

Post doc available: The role of transcriptional and regulatory changes during compensatory evolution

Arnar Pálsson, 18/02/2016

Post doc available: The role of transcriptional and regulatory changes during compensatory evolution

Which principles influence the rewiring and tuning of gene regulatory networks? How do those network react to genetic perturbations? We are seeking a post-doc to tackle those and related questions in project utilizing populations of Drosophila that have undergone compensatory adaptation using experimental evolution and artificial selection. The project involves the analysis of tissue specific RNA-seq and numerical analyses. The ideal candidate is strong in evolutionary genetics, statistical and bioinformatic analyses and with capable hands for molecular biology. Excellent communication skills, main focus on writing, are required, as is a solid publication record. The candidate will be encouraged (and given time) to develop their own research program.

The project involves a collaboration between University of Iceland and McMaster University, with approx. 3/4 of the work conducted in Iceland and 1/4 in Canada. Those interested are asked to send a cover letter detailing research interests and experience, a current CV, and contact details for three professional references by April 1st. Anticipated start date is Fall 2016, but this is flexible. The position is funded by the Icelandic Research fund (for 2 years), salary commensurate with qualifications.

The University of Iceland is the leading research institute in the country, and groups at the Institute of biology ( and Biomedical Center ( study genomics, evolutionary, developmental, cellular and molecular biology. The shared facilities include High throughput sequencers, various specialized molecular biology equipment and computer clusters. The University is an equal opportunity workplace with strong combination of international and domestic scientists.

Learn more about the work in the Palsson ( and Dworkin ( labs.

Please send applications and/or inquiries to

This project is built on work on indel polymorphism in the even skipped stripes 3+7 enhancer and on the conditional effects of genetic backgrounds on wing mutations.

Palsson A, Wesolowska N, Reynisdóttir S, Ludwig MZ, Kreitman M (2014) Naturally Occurring Deletions of Hunchback Binding Sites in the Even-Skipped Stripe 3+7 Enhancer. PLoS ONE 9(5): e91924. doi:10.1371/journal.pone.0091924

Chari S, Dworkin I (2013) The Conditional Nature of Genetic Interactions: The Consequences of Wild-Type Backgrounds on Mutational Interactions in a Genome-Wide Modifier Screen. PLoS Genet 9(8): e1003661. doi:10.1371/journal.pgen.1003661