Hehenberger
Elisabeth
Hehenberger
Elisabeth
No Thumbnail Available
Search Results
Now showing
1 - 5 of 5
-
ArticleA kleptoplastidic dinoflagellate and the tipping point between transient and fully integrated plastid endosymbiosis(National Academy of Sciences, 2019-09-03) Hehenberger, Elisabeth ; Gast, Rebecca J. ; Keeling, Patrick J.Plastid endosymbiosis has been a major force in the evolution of eukaryotic cellular complexity, but how endosymbionts are integrated is still poorly understood at a mechanistic level. Dinoflagellates, an ecologically important protist lineage, represent a unique model to study this process because dinoflagellate plastids have repeatedly been reduced, lost, and replaced by new plastids, leading to a spectrum of ages and integration levels. Here we describe deep-transcriptomic analyses of the Antarctic Ross Sea dinoflagellate (RSD), which harbors long-term but temporary kleptoplasts stolen from haptophyte prey, and is closely related to dinoflagellates with fully integrated plastids derived from different haptophytes. In some members of this lineage, called the Kareniaceae, their tertiary haptophyte plastids have crossed a tipping point to stable integration, but RSD has not, and may therefore reveal the order of events leading up to endosymbiotic integration. We show that RSD has retained its ancestral secondary plastid and has partitioned functions between this plastid and the kleptoplast. It has also obtained genes for kleptoplast-targeted proteins via horizontal gene transfer (HGT) that are not derived from the kleptoplast lineage. Importantly, many of these HGTs are also found in the related species with fully integrated plastids, which provides direct evidence that genetic integration preceded organelle fixation. Finally, we find that expression of kleptoplast-targeted genes is unaffected by environmental parameters, unlike prey-encoded homologs, suggesting that kleptoplast-targeted HGTs have adapted to posttranscriptional regulation mechanisms of the host.
-
ArticleGenetic tool development in marine protists: emerging model organisms for experimental cell biology(Nature Research, 2020-04-06) Faktorová, Drahomíra ; Nisbet, R. Ellen R. ; Fernández Robledo, José A. ; Casacuberta, Elena ; Sudek, Lisa ; Allen, Andrew E. ; Ares, Manuel, Jr. ; Aresté, Cristina ; Balestreri, Cecilia ; Barbrook, Adrian C. ; Beardslee, Patrick ; Bender, Sara J. ; Booth, David S. ; Bouget, François-Yves ; Bowler, Chris ; Breglia, Susana A. ; Brownlee, Colin ; Burger, Gertraud ; Cerutti, Heriberto ; Cesaroni, Rachele ; Chiurillo, Miguel A. ; Clemente, Thomas ; Coles, Duncan B. ; Collier, Jackie L. ; Cooney, Elizabeth C. ; Coyne, Kathryn J. ; Docampo, Roberto ; Dupont, Christopher L. ; Edgcomb, Virginia P. ; Einarsso, Elin ; Elustondo, Pía A. ; Federici, Fernan ; Freire-Beneitez, Veronica ; Freyria, Nastasia J. ; Fukuda, Kodai ; García, Paulo A. ; Girguis, Peter R. ; Gomaa, Fatma ; Gornik, Sebastian G. ; Guo, Jian ; Hampl, Vladimír ; Hanawa, Yutaka ; Haro-Contreras, Esteban R. ; Hehenberger, Elisabeth ; Highfield, Andrea ; Hirakawa, Yoshihisa ; Hopes, Amanda ; Howe, Christopher J. ; Hu, Ian ; Ibañez, Jorge ; Irwin, Nicholas A. T. ; Ishii, Yuu ; Janowicz, Natalia Ewa ; Jones, Adam C. ; Kachale, Ambar ; Fujimura-Kamada, Konomi ; Kaur, Binnypreet ; Kaye, Jonathan Z. ; Kazana, Eleanna ; Keeling, Patrick J. ; King, Nicole ; Klobutcher, Lawrence A. ; Lander, Noelia ; Lassadi, Imen ; Li, Zhuhong ; Lin, Senjie ; Lozano, Jean-Claude ; Luan, Fulei ; Maruyama, Shinichiro ; Matute, Tamara ; Miceli, Cristina ; Minagawa, Jun ; Moosburner, Mark ; Najle, Sebastián R. ; Nanjappa, Deepak ; Nimmo, Isabel C. ; Noble, Luke ; Novák Vanclová, Anna M. G. ; Nowacki, Mariusz ; Nuñez, Isaac ; Pain, Arnab ; Piersanti, Angela ; Pucciarelli, Sandra ; Pyrih, Jan ; Rest, Joshua S. ; Rius, Mariana ; Robertson, Deborah ; Ruaud, Albane ; Ruiz-Trillo, Iñaki ; Sigg, Monika A. ; Silver, Pamela A. ; Slamovits, Claudio H. ; Smith, G. Jason ; Sprecher, Brittany N. ; Stern, Rowena ; Swart, Estienne C. ; Tsaousis, Anastasios D. ; Tsypin, Lev ; Turkewitz, Aaron ; Turnšek, Jernej ; Valach, Matus ; Vergé, Valérie ; von Dassow, Peter ; von der Haar, Tobias ; Waller, Ross F. ; Wang, Lu ; Wen, Xiaoxue ; Wheeler, Glen L. ; Woods, April ; Zhang, Huan ; Mock, Thomas ; Worden, Alexandra Z. ; Lukes, JuliusDiverse microbial ecosystems underpin life in the sea. Among these microbes are many unicellular eukaryotes that span the diversity of the eukaryotic tree of life. However, genetic tractability has been limited to a few species, which do not represent eukaryotic diversity or environmentally relevant taxa. Here, we report on the development of genetic tools in a range of protists primarily from marine environments. We present evidence for foreign DNA delivery and expression in 13 species never before transformed and for advancement of tools for eight other species, as well as potential reasons for why transformation of yet another 17 species tested was not achieved. Our resource in genetic manipulation will provide insights into the ancestral eukaryotic lifeforms, general eukaryote cell biology, protein diversification and the evolution of cellular pathways.
-
ArticleGenomes from uncultivated Pelagiphages reveal multiple phylogenetic clades exhibiting extensive auxiliary metabolic genes and cross-family multigene transfers(American Society for Microbiology, 2022-08-16) Wittmers, Fabian ; Needham, David M. ; Hehenberger, Elisabeth ; Giovannoni, Stephen J. ; Worden, Alexandra Z.For the abundant marine Alphaproteobacterium Pelagibacter (SAR11), and other bacteria, phages are powerful forces of mortality. However, little is known about the most abundant Pelagiphages in nature, such as the widespread HTVC023P-type, which is currently represented by two cultured phages. Using viral metagenomic data sets and fluorescence-activated cell sorting, we recovered 80 complete, undescribed Podoviridae genomes that form 10 phylogenomically distinct clades (herein, named Clades I to X) related to the HTVC023P-type. These expanded the HTVC023P-type pan-genome by 15-fold and revealed 41 previously unknown auxiliary metabolic genes (AMGs) in this viral lineage. Numerous instances of partner-AMGs (colocated and involved in related functions) were observed, including partners in nucleotide metabolism, DNA hypermodification, and Curli biogenesis. The Type VIII secretion system (T8SS) responsible for Curli biogenesis was identified in nine genomes and expanded the repertoire of T8SS proteins reported thus far in viruses. Additionally, the identified T8SS gene cluster contained an iron-dependent regulator (FecR), as well as a histidine kinase and adenylate cyclase that can be implicated in T8SS function but are not within T8SS operons in bacteria. While T8SS are lacking in known Pelagibacter, they contribute to aggregation and biofilm formation in other bacteria. Phylogenetic reconstructions of partner-AMGs indicate derivation from cellular lineages with a more recent transfer between viral families. For example, homologs of all T8SS genes are present in syntenic regions of distant Myoviridae Pelagiphages, and they appear to have alphaproteobacterial origins with a later transfer between viral families. The results point to an unprecedented multipartner-AMG transfer between marine Myoviridae and Podoviridae. Together with the expansion of known metabolic functions, our studies provide new prospects for understanding the ecology and evolution of marine phages and their hosts.
-
ArticlePhosphate limitation responses in marine green algae are linked to reprogramming of the tRNA epitranscriptome and codon usage bias(Oxford University Press, 2023-11-21) Hehenberger, Elisabeth ; Guo, Jian ; Wilken, Susanne ; Hoadley, Kenneth ; Sudek, Lisa ; Poirier, Camille ; Dannebaum, Richard ; Susko, Edward ; Worden, Alexandra Z.Marine algae are central to global carbon fixation, and their productivity is dictated largely by resource availability. Reduced nutrient availability is predicted for vast oceanic regions as an outcome of climate change; however, there is much to learn regarding response mechanisms of the tiny picoplankton that thrive in these environments, especially eukaryotic phytoplankton. Here, we investigate responses of the picoeukaryote Micromonas commoda, a green alga found throughout subtropical and tropical oceans. Under shifting phosphate availability scenarios, transcriptomic analyses revealed altered expression of transfer RNA modification enzymes and biased codon usage of transcripts more abundant during phosphate-limiting versus phosphate-replete conditions, consistent with the role of transfer RNA modifications in regulating codon recognition. To associate the observed shift in the expression of the transfer RNA modification enzyme complement with the transfer RNAs encoded by M. commoda, we also determined the transfer RNA repertoire of this alga revealing potential targets of the modification enzymes. Codon usage bias was particularly pronounced in transcripts encoding proteins with direct roles in managing phosphate limitation and photosystem-associated proteins that have ill-characterized putative functions in “light stress.” The observed codon usage bias corresponds to a proposed stress response mechanism in which the interplay between stress-induced changes in transfer RNA modifications and skewed codon usage in certain essential response genes drives preferential translation of the encoded proteins. Collectively, we expose a potential underlying mechanism for achieving growth under enhanced nutrient limitation that extends beyond the catalog of up- or downregulated protein-encoding genes to the cell biological controls that underpin acclimation to changing environmental conditions.
-
ArticleGradients of bacteria in the oceanic water column reveal finely-resolved vertical distributions(Public Library of Science, 2024-04-02) Harbeitner, Rachel C. ; Wittmers, Fabian ; Yung, Charmaine C. M. ; Eckmann, Charlotte A. ; Hehenberger, Elisabeth ; Blum, Marguerite ; Needham, David M. ; Worden, Alexandra Z.Bacterial communities directly influence ecological processes in the ocean, and depth has a major influence due to the changeover in primary energy sources between the sunlit photic zone and dark ocean. Here, we examine the abundance and diversity of bacteria in Monterey Bay depth profiles collected from the surface to just above the sediments (e.g., 2000 m). Bacterial abundance in these Pacific Ocean samples decreased by >1 order of magnitude, from 1.22 ±0.69 ×106 cells ml-1 in the variable photic zone to 1.44 ± 0.25 ×105 and 6.71 ± 1.23 ×104 cells ml-1 in the mesopelagic and bathypelagic, respectively. V1-V2 16S rRNA gene profiling showed diversity increased sharply between the photic and mesopelagic zones. Weighted Gene Correlation Network Analysis clustered co-occurring bacterial amplicon sequence variants (ASVs) into seven subnetwork modules, of which five strongly correlated with depth-related factors. Within surface-associated modules there was a clear distinction between a ‘copiotrophic’ module, correlating with chlorophyll and dominated by e.g., Flavobacteriales and Rhodobacteraceae, and an ‘oligotrophic’ module dominated by diverse Oceanospirillales (such as uncultured JL-ETNP-Y6, SAR86) and Pelagibacterales. Phylogenetic reconstructions of Pelagibacterales and SAR324 using full-length 16S rRNA gene data revealed several additional subclades, expanding known microdiversity within these abundant lineages, including new Pelagibacterales subclades Ia.B, Id, and IIc, which comprised 4–10% of amplicons depending on the subclade and depth zone. SAR324 and Oceanospirillales dominated in the mesopelagic, with SAR324 clade II exhibiting its highest relative abundances (17±4%) in the lower mesopelagic (300–750 m). The two newly-identified SAR324 clades showed highest relative abundances in the photic zone (clade III), while clade IV was extremely low in relative abundance, but present across dark ocean depths. Hierarchical clustering placed microbial communities from 900 m samples with those from the bathypelagic, where Marinimicrobia was distinctively relatively abundant. The patterns resolved herein, through high resolution and statistical replication, establish baselines for marine bacterial abundance and taxonomic distributions across the Monterey Bay water column, against which future change can be assessed.