Symbioses between eukaryotes and nitrogen-fixing cyanobacteria off Brazil

Seminar at the Pontifical University of Chile in Santiago and the Universidad de Concepcion (ECODIM mini symposium).
Based on our paper in ISME: https://www.nature.com/articles/s41396-018-0050-z

1. Catherine Ribeiro, Adriana Lopes dos Santos, Dominique, Marie, Frederico Brandini, Daniel Vaulot Station Biologique de Roscoff, UPMC et CNRS, France Universidade de São Paulo, Brasil Symbiosis between nitrogen-fixing bacteria and eukaryotes on the continental shelf of Brazil
2. N2 fixation in the ocean Trichodesmium
3. Nitrogen fixing cyanabacteria nifH gene
4. Identifying UCYN-A
5. UCYN-A lacks critical genes
6. UCYN-A occurs in Symbiosis with Eukaryote UCYN-A Eukaryote NanoSIMS N15 enrichment
8. The plot thickens 16S rRNA
9. Genome of UCYN-A1 vs A2 86% similarity at AA level 135 genes
10. The plot thickens again... Three types of UCYN-A Different hosts A1 A2 A3 ?
11. Always more clades... A1 -> A6
12. UCYN-A is major contributor to N2 fixation Trichodesmium UCYN-A
13. Distribution of hosts A1 Host A2 Host CARBOM
14. CARBOM cruise - Continental shelf Brazil SACW BC
15. TR1 TR2 Pico and Nanoeukaryotes Picoeukaryotes Nanoeukaryotes
16. 16S rRNA from sorted cells Chrysophyc Clade B2 Isochrysidales Braarudosphaeraceae EF051761 - Chrysochromulina campanulifera - strain UIO J10 HM133350 - Biosope T60 16S OXY107.017 HM133259 - Biosope T41 16S PLA491.033 LK391826 - Ochromonas sp. - strain F933 HM133175 - Biosope T35 16S PLA491.033 St.98 surf PEUK clone F4 St.TRICHO surf PEUK clone B1 St.98 surf NEUK clone C2 HM133499 - Biosope T84 16S PLA491.026 HM133324 - Biosope T58 16S PLA491.010 LN735407 - Emiliania huxleyi - strain RCC 2941 KP282836 - Gephyrocapsa muellerae - strain RCC3862 LK391825 - Chrysochromulina apheles - strain F929 St.98 surf PEUK clone E5 HM133343 - Biosope T60 16S OXY107.004 HM133380 - Biosope T60 16S PLA491.021 HM133420 - Biosope T65 16S.38a AB847984 - Braarudosphaera bigelowii - strain TMRscBb1 2 2 7 15 picoplankton sequences nanoplankton sequences 69 100 99 57 88 92 99 90 100
17. Strategy • Samples preserved with DMSO 10% • Two fractions sorted by flow cytometry : Pico and Nano (56 samples) • Two genes – nuclear 18S rRNA (V4) – nifH • 1 run Ilumina MiSeq 2*250 bp • Analysis with Mothur • Assignement : PR2, BLAST
18. 18S rRNA classes
19. 18S rRNA OTUs
20. 18S rRNA classes
21. Bray distance clustering based on major 18S OTUs Dinos Mam Prym Diatoms Chrys UCYN-A1 host Ostreo + Bathy Prymnesiophyceae Prorocentrum
22. Picoeukaryote communities are structured by the environment
23. nifH diversity A1 A3 Tricho A2 A4
24. A1 A3 Tricho A2 Bray distance clustering based on major nifH OTUs A4
25. 18S vs nifH
26. Network analysis using 18S rRNA and nifH "Pico" network SparCC
27. Conclusion On the shelf off Brazil • Two major types photosynthetic eukaryotic communities : – Braarudosphaeraceae – Ostreococcus + Bathycoccus • Nitrogen fixers – UCYN-A is dominant nitrogen fixer : A1, A2, A3, A4 • Network analysis – Recover A1 and A2 associations – A4 could have same host than A2 (Braarudosphaera) – A3 ?
28. Breaking news ... "Pomacytosis"
29. Breaking news ... UCYN-A Eukaryote
30. Breaking news ...