255 results on '"von Dassow, P."'
Search Results
2. Raising predatory babies: development from fertilization to sexual maturity of the hoplonemertean Emplectonema viride (Nemertea)
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Mendes, Cecili B., von Dassow, George, Andrade, Sónia C. S., and Maslakova, Svetlana
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- 2023
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3. Publisher Correction: Patterning of the cell cortex by Rho GTPases
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Bement, William M., Goryachev, Andrew B., Miller, Ann L., and von Dassow, George
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- 2024
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4. Local scale extreme low pH conditions and genetic differences shape phenotypic variation in a broad dispersal copepod species
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Victor M. Aguilera, Fabiola Sepulveda, Peter von Dassow, Juan Diego Gaitán-Espitia, Andrés Mesas, and Cristian A. Vargas
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coastal variability ,carbon chemistry ,extreme events ,temperate and subtropical systems ,gene flow ,phenotypic plasticity ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Extreme low pH events in estuaries and upwelling areas can modulate the phenotypic and genetic diversity of natural populations. To test this hypothesis, we explored the linkage between local scale extreme low pH events, genetic diversity, and variation in fecundity-related traits (body size, egg size, and egg production rate) in the broad-dispersal copepod Acartia tonsa. We assessed genetic and phenotypic characteristics of populations by contrasting extreme low pH environments (upwelling and temperate estuary) in the coastal Southeast Pacific, under natural and experimental conditions. These populations showed significant genetic differentiation with higher diversity in mitochondrial and nuclear loci (encoding mtCOI and 18S rRNA) in the estuarine population. Copepods from this population are exposed to more frequent extreme low pH events (< 7.7), and the adult females exhibit consistent phenotypic variation in body size, egg size, and egg production rate across different cohorts. Experimental acclimation to extreme low pH conditions revealed no significant differences in fecundity-related traits between A. tonsa populations. Although these results partially support our hypothesis, the experimental findings suggest other drivers might also influence phenotypic differences in the local environments.
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- 2023
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5. Abundances and morphotypes of the coccolithophore Emiliania huxleyi in southern Patagonia compared to neighbouring oceans and Northern Hemisphere fjords
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F. Díaz-Rosas, C. Alves-de-Souza, E. Alarcón, E. Menschel, H. E. González, R. Torres, and P. von Dassow
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Ecology ,QH540-549.5 ,Life ,QH501-531 ,Geology ,QE1-996.5 - Abstract
Coccolithophores are potentially affected by ongoing ocean acidification, where rising CO2 lowers seawater pH and calcite saturation state (Ωcal). Southern Patagonian fjords and channels provide natural laboratories for studying these issues due to high variability in physical and chemical conditions. We surveyed coccolithophore assemblages in Patagonian fjords during late spring 2015 and early spring 2017. Surface Ωcal exhibited large variations driven mostly by freshwater inputs. High-Ωcal conditions (max. 3.6) occurred in the Archipelago Madre de Dios. Ωcal ranged from 2.0–2.6 in the western Strait of Magellan and 1.5–2.2 in the inner channel and was subsaturating (0.5) in Skyring Sound. Emiliania huxleyi was the only coccolithophore widely distributed in Patagonian fjords (> 96 % of total coccolithophores), only disappearing in the Skyring Sound, a semi-closed mesohaline system. Correspondence analysis associated higher E. huxleyi biomasses with lower diatom biomasses. The highest E. huxleyi abundances in Patagonia were in the lower range of those reported in Norwegian fjords. Predominant morphotypes were distinct from those previously documented in nearby oceans but similar to those of Norwegian fjords. Moderately calcified forms of E. huxleyi A morphotype were uniformly distributed throughout Patagonia fjords. The exceptional R/hyper-calcified coccoliths, associated with low Ωcal values in Chilean and Peruvian coastal upwellings, were a minor component associated with high Ωcal levels in Patagonia. Outlying mean index (OMI) niche analysis suggested that pH and Ωcal conditions explained most variation in the realized niches of E. huxleyi morphotypes. The moderately calcified A morphotype exhibited the widest niche breadth (generalist), while the R/hyper-calcified morphotype exhibited a more restricted realized niche (specialist). Nevertheless, when considering an expanded sampling domain, including nearby southeast Pacific coastal and offshore waters, even the R/hyper-calcified morphotype exhibited a higher niche breadth than other closely phylogenetically related coccolithophore species. The occurrence of E. huxleyi in naturally low pH–Ωcal environments indicates that its ecological response is plastic and capable of adaptation.
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- 2021
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6. Carbon Assimilation by the Picoplanktonic Community Inhabiting the Secondary Chlorophyll Maximum of the Anoxic Marine Zones of the Eastern Tropical North and South Pacific
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Montserrat Aldunate, Peter von Dassow, Cristian A. Vargas, and Osvaldo Ulloa
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autotrophy ,secondary chlorophyll maximum ,oxygen minimum zones ,anoxia ,Prochlorococcus ,heterotrophy ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Anoxic marine zones (AMZs) constitute pelagic systems distinguished from the oxygen minimum zones (OMZs) by the complete absence of detectable oxygen and the accumulation of nitrite in mid-waters. At the top of the oxygen-depleted layer and below the oxycline, nutrients are abundant; light intensity is very much reduced (
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- 2022
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7. Do Differences in Latitudinal Distributions of Species and Organelle Haplotypes Reflect Thermal Reaction Norms Within the Emiliania/Gephyrocapsa Complex?
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Peter von Dassow, Paula Valentina Muñoz Farías, Sarah Pinon, Esther Velasco-Senovilla, and Simon Anguita-Salinas
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Emiliania huxleyi ,Gephyrocapsa ,phytoplankton ,thermal reaction norms ,thermal performance curves ,haplogroup ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The cosmopolitan phytoplankter Emiliania huxleyi contrasts with its closest relatives that are restricted to narrower latitudinal bands, making it interesting for exploring how alternative outcomes in phytoplankton range distributions arise. Mitochondrial and chloroplast haplogroups within E. huxleyi are shared with their closest relatives: Some E. huxleyi share organelle haplogroups with Gephyrocapsa parvula and G. ericsonii which inhabit lower latitudes, while other E. huxleyi share organelle haplogroups with G. muellerae, which inhabit high latitudes. We investigated whether the phylogeny of E. huxleyi organelles reflects environmental gradients, focusing on the Southeast Pacific where the different haplogroups and species co-occur. There was a high congruence between mitochondrial and chloroplast haplogroups within E. huxleyi. Haplogroup II of E. huxleyi is negatively associated with cooler less saline waters, compared to haplogroup I, both when analyzed globally and across temporal variability at the small special scale of a center of coastal upwelling at 30° S. A new mitochondrial haplogroup Ib detected in coastal Chile was associated with warmer waters. In an experiment focused on inter-species comparisons, laboratory-determined thermal reaction norms were consistent with latitudinal/thermal distributions of species, with G. oceanica exhibiting warm thermal optima and tolerance and G. muellerae exhibiting cooler thermal optima and tolerances. Emiliania huxleyi haplogroups I and II tended to exhibit a wider thermal niche compared to the other Gephyrocapsa, but no differences among haplogroups within E. huxleyi were found. A second experiment, controlling for local adaptation and time in culture, found a significant difference between E. huxleyi haplogroups. The difference between I and II was of the expected sign, but not the difference between I and Ib. The differences were small (≤1°C) compared to differences reported previously within E. huxleyi by local adaptation and even in-culture evolution. Haplogroup Ib showed a narrower thermal niche. The cosmopolitanism of E. huxleyi might result from both wide-spread generalist phenotypes and specialist phenotypes, as well as a capacity for local adaptation. Thermal reaction norm differences can well explain the species distributions but poorly explain distributions among mitochondrial haplogroups within E. huxleyi. Perhaps organelle haplogroup distributions reflect historical rather than selective processes.
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- 2021
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8. Genetic tool development in marine protists: emerging model organisms for experimental cell biology
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Faktorová, Drahomíra, Nisbet, R. Ellen R., Fernández Robledo, José A., Casacuberta, Elena, Sudek, Lisa, Allen, Andrew E., Ares, Jr, Manuel, Aresté, Cristina, Balestreri, Cecilia, Barbrook, Adrian C., Beardslee, Patrick, Bender, Sara, 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, Docampo, Roberto, Dupont, Christopher L., Edgcomb, Virginia, Einarsson, 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., Jason Smith, G., 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, Woods, April, Zhang, Huan, Mock, Thomas, Worden, Alexandra Z., and Lukeš, Julius
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- 2020
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9. A Comparative Analysis of Spindle Morphometrics across Metazoans
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Crowder, Marina E, Strzelecka, Magdalena, Wilbur, Jeremy D, Good, Matthew C, von Dassow, George, and Heald, Rebecca
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Underpinning research ,1.1 Normal biological development and functioning ,Generic health relevance ,Animals ,Chordata ,Embryo ,Mammalian ,Embryo ,Nonmammalian ,Female ,Invertebrates ,Male ,Spindle Apparatus ,Biological Sciences ,Medical and Health Sciences ,Psychology and Cognitive Sciences ,Developmental Biology - Abstract
Cell division in all eukaryotes depends on function of the spindle, a microtubule-based structure that segregates chromosomes to generate daughter cells in mitosis or haploid gametes in meiosis. Spindle size adapts to changes in cell size and shape, which vary dramatically across species and within a multicellular organism, but the nature of scaling events and their underlying mechanisms are poorly understood. Cell size variations are most pronounced in early animal development, as egg diameters range from tens of microns up to millimeters across animal phyla, and decrease several orders of magnitude during rapid reductive divisions. During early embryogenesis in the model organisms X. laevis and C. elegans, the spindle scales with cell size [1, 2], a phenomenon regulated by molecules that modulate microtubule dynamics [3-6], as well as by limiting cytoplasmic volume [7, 8]. However, it is not known to what extent spindle scaling is conserved across organisms and among different cell types. Here we show that in a range of metazoan phyla, mitotic spindle length decreased with cell size across an ∼30-fold difference in zygote size. Maximum spindle length varied, but linear spindle scaling occurred similarly in all species once embryonic cell diameter reduced to 140 μm. In contrast, we find that the female meiotic spindle does not scale as closely to egg size, adopting a more uniform size across species that most likely reflects its specialized function. Our analysis reveals that spindle morphometrics change abruptly, within one cell cycle, at the transition from meiosis to mitosis in most animals.
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- 2015
10. Metagenome Sequencing of the Microbial Community of a Solar Saltern Crystallizer Pond at Cáhuil Lagoon, Chile
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Plominsky, Alvaro M, Delherbe, Nathalie, Ugalde, Juan A, Allen, Eric E, Blanchet, Marine, Ikeda, Priscila, Santibañez, Francisco, Hanselmann, Kurt, Ulloa, Osvaldo, De la Iglesia, Rodrigo, von Dassow, Peter, Astorga, Marcia, Gálvez, María Jesús, González, María Lorena, Henríquez-Castillo, Carlos, Vaulot, Daniel, do Santos, Adriana Lopes, van den Engh, Gerrit, Gimpel, Carla, Bertoglio, Florencia, Delgado, Yolaine, Docmac, Felipe, Elizondo-Patrone, Claudia, Narváez, Silvia, Sorroche, Fernando, Rojas-Herrera, Marcelo, and Trefault, Nicole
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Microbiology ,Biological Sciences ,Biochemistry and Cell Biology ,Genetics - Abstract
Cáhuil Lagoon in central Chile harbors distinct microbial communities in various solar salterns that are arranged as interconnected ponds with increasing salt concentrations. Here, we report the metagenome of the 3.0- to 0.2-µm fraction of the microbial community present in a crystallizer pond with 34% salinity.
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- 2014
11. Size-Fractionated Contribution of Microbial Biomass to Suspended Organic Matter in the Eastern Tropical South Pacific Oxygen Minimum Zone
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Sebastian I. Cantarero, Carlos Henríquez-Castillo, Nadia Dildar, Cristian A. Vargas, Peter von Dassow, Marcela Cornejo-D’Ottone, and Julio Sepúlveda
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intact polar lipids ,oxygen minimum zone ,marine biogeochemistry ,biomarker ,microbial biomass ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Cell membrane intact polar lipids (IPLs) are chemotaxonomic biomarkers whose abundances and distributions in water column environments reflect the living biomass of in situ microbial communities, and can be used to determine the relative contribution of distinct functional and phylogenetic groups to water column carbon stocks. The diversity of IPLs in marine environments is, however, vast, while our knowledge of their biological origins remains limited. Here, we study the distribution of IPLs in size-fractionated suspended organic matter from the oxygen minimum zone (OMZ) of the eastern tropical South Pacific (ETSP) off northern Chile. Canonical correspondence analyses of total IPL abundances and water column physiochemistry demonstrate distinct distributions of microbial sources associated with different geochemical regions in the water column (chlorophyll maximum, upper chemocline, lower chemocline, upper OMZ, core OMZ, and mesopelagic region). Furthermore, the distribution of IPLs in free-living (0.3–2.7 μm) and particle-attached (2.7–53 μm) suspended organic matter differs, suggesting distinct biological sources in each size fraction. While some parallels exist, the diversity and distribution of IPLs in the OMZ system of the ETSP off northern Chile exhibited some unique features compared to other OMZ systems; for instance, we observed a significantly lower contribution of betaine lipids from phytoplanktonic sources, possibly reflecting a physiological response to severe N-limitation in this area. The overall IPL abundance in the two size fractions also indicates a dominance of free-living biomass in the OMZ and mesopelagic regions, suggesting that these areas of the water column could provide additional sources of submicrometer-sized organic carbon to deeper waters. This study improves the utility of IPLs as chemotaxonomic biomarkers by providing insight into the contrasting distributions of microbial biomass from different life modes (free-living and particle-attached). Our results suggest that microbial production in low oxygen environments may be more important to total water column carbon stocks than previously thought.
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- 2020
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12. Response of Phytoplankton Assemblages From Naturally Acidic Coastal Ecosystems to Elevated pCO2
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Natalia Osma, Laura Latorre-Melín, Bárbara Jacob, Paulina Y. Contreras, Peter von Dassow, and Cristian A. Vargas
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climate change ,environmental variability ,carbonate chemistry ,community structure ,coastal upwelling ,estuary ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The interplay of coastal oceanographic processes usually results in partial pressures of CO2 (pCO2) higher than expected from the equilibrium with the atmosphere and even higher than those expected by the end of the century. Although this is a well-known situation, the natural variability of seawater chemistry at the locations from which tested organisms or communities originate is seldom considered in ocean acidification experiments. In this work, we aimed to evaluate the role of the carbonate chemistry dynamics in shaping the response of coastal phytoplankton communities to increased pCO2 levels. The study was conducted at two coastal ecosystems off Chile, the Valdivia River estuary and the coastal upwelling ecosystem in the Arauco Gulf. We characterized the seasonal variability (winter/summer) of the hydrographic conditions, the carbonate system parameters, and the phytoplankton community structure at both sites. The results showed that carbonate chemistry dynamics in the estuary were mainly related to seasonal changes in freshwater discharges, with acidic and corrosive conditions dominating in winter. In the Arauco Gulf, these conditions were observed in summer, mainly associated with the upwelling of cold and high pCO2 (>1,000 μatm) waters. Diatoms dominated the phytoplankton communities at both sites, yet the one in Valdivia was more diverse. Only certain phytoplankton groups in this latter ecosystem showed a significant correlations with the carbonate system parameters. When the impact of elevated pCO2 levels was investigated by pCO2 manipulation experiments, we did not observe any significant effect on the biomass of either of the two communities. Changes in the phytoplankton species composition and abundance during the incubations were related to other factors, such as competition and growth phases. Our findings highlight the importance of the natural variability of coastal ecosystems and the potential for local adaptation in determining responses of coastal phytoplankton communities to increased pCO2 levels.
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- 2020
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13. Over-calcified forms of the coccolithophore Emiliania huxleyi in high-CO2 waters are not preadapted to ocean acidification
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P. von Dassow, F. Díaz-Rosas, E. M. Bendif, J.-D. Gaitán-Espitia, D. Mella-Flores, S. Rokitta, U. John, and R. Torres
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Ecology ,QH540-549.5 ,Life ,QH501-531 ,Geology ,QE1-996.5 - Abstract
Marine multicellular organisms inhabiting waters with natural high fluctuations in pH appear more tolerant to acidification than conspecifics occurring in nearby stable waters, suggesting that environments of fluctuating pH hold genetic reservoirs for adaptation of key groups to ocean acidification (OA). The abundant and cosmopolitan calcifying phytoplankton Emiliania huxleyi exhibits a range of morphotypes with varying degrees of coccolith mineralization. We show that E. huxleyi populations in the naturally acidified upwelling waters of the eastern South Pacific, where pH drops below 7.8 as is predicted for the global surface ocean by the year 2100, are dominated by exceptionally over-calcified morphotypes whose distal coccolith shield can be almost solid calcite. Shifts in morphotype composition of E. huxleyi populations correlate with changes in carbonate system parameters. We tested if these correlations indicate that the hyper-calcified morphotype is adapted to OA. In experimental exposures to present-day vs. future pCO2 (400 vs. 1200 µatm), the over-calcified morphotypes showed the same growth inhibition (−29.1±6.3 %) as moderately calcified morphotypes isolated from non-acidified water (−30.7±8.8 %). Under the high-CO2–low-pH condition, production rates of particulate organic carbon (POC) increased, while production rates of particulate inorganic carbon (PIC) were maintained or decreased slightly (but not significantly), leading to lowered PIC ∕ POC ratios in all strains. There were no consistent correlations of response intensity with strain origin. The high-CO2–low-pH condition affected coccolith morphology equally or more strongly in over-calcified strains compared to moderately calcified strains. High-CO2–low-pH conditions appear not to directly select for exceptionally over-calcified morphotypes over other morphotypes, but perhaps indirectly by ecologically correlated factors. More generally, these results suggest that oceanic planktonic microorganisms, despite their rapid turnover and large population sizes, do not necessarily exhibit adaptations to naturally high-CO2 upwellings, and this ubiquitous coccolithophore may be near the limit of its capacity to adapt to ongoing ocean acidification.
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- 2018
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14. Cane Handles for Teapots.
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von Dassow, Sumi
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TEAPOTS ,POTTERY - Abstract
This article from Pottery Making Illustrated provides instructions on how to create cane handles for teapots. The author explains that a well-functioning teapot requires a body, spout, lid, and handle that work together harmoniously. The article discusses different handle options based on the shape of the teapot and recommends using a cane handle attached through lug handles. The author provides step-by-step instructions on preparing the materials, starting and binding the cane handle, and finishing the handle. The article also mentions that the handle can be customized with various embellishments and offers information about the author's background in pottery. [Extracted from the article]
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- 2024
15. The trochoblasts in the pilidium larva break an ancient spiralian constraint to enable continuous larval growth and maximally indirect development
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George von Dassow and Svetlana A. Maslakova
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Nemertea ,Pilidium ,Spiral cleavage ,Cell fate specification ,Fate map ,Maximally indirect development ,Evolution ,QH359-425 - Abstract
Abstract Background Nemertean embryos undergo equal spiral cleavage, and prior fate-mapping studies showed that some also exhibit key aspects of spiralian lineage-based fate specification, including specification of the primary trochoblasts, which differentiate early as the core of the prototroch of the spiralian trochophore larva. Yet it remains unclear how the nemertean pilidium larva, a long-lived planktotroph that grows substantially as it builds a juvenile body from isolated rudiments, develops within the constraints of spiral cleavage. Results We marked single cells in embryos of the pilidiophoran Maculaura alaskensis to show that primary, secondary, and accessory trochoblasts, cells that would make the prototroch in conventional spiralian trochophores (1q2, 1q12, and some descendants of 2q), fully account for the pilidium’s primary ciliary band, but without undergoing early cleavage arrest. Instead, the primary ciliary band consists of many small, albeit terminally differentiated, cells. The trochoblasts also give rise to niches of indefinitely proliferative cells (“axils”) that sustain continuous growth of the larval body, including new ciliated band. Several of the imaginal rudiments that form the juvenile body arise from the axils: in particular, we show that cephalic imaginal disks originate from 1a2 and 1b12 and that trunk imaginal disks likely originate from 2d. Conclusions The pilidium exhibits a familiar relation between identified blastomeres and the primary ciliated band, but the manner in which these cells form this organ differs fundamentally from the way equivalent cells construct the trochophore’s prototroch. Also, the establishment, by some progeny of the putative trochoblasts, of indeterminate stem cell populations that give rise to juvenile rudiments, as opposed to an early cleavage arrest, implies a radical alteration in their developmental program. This transition may have been essential to the evolution of a maximally indirect developing larval form—the pilidium—among nemerteans.
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- 2017
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16. Do phytoplankton require oxygen to survive? A hypothesis and model synthesis from oxygen minimum zones
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Wong, JCY, Raven, JA, Aldunate, M, Silva, S, Gaitán-Espitia, JD, Vargas, CA, Ulloa, O, von Dassow, P, Wong, JCY, Raven, JA, Aldunate, M, Silva, S, Gaitán-Espitia, JD, Vargas, CA, Ulloa, O, and von Dassow, P
- Abstract
It is commonly known that phytoplankton have a pivotal role in marine biogeochemistry and ecosystems as carbon fixers and oxygen producers, but their response to deoxygenation has scarcely been studied. Nonetheless, in the major oceanic oxygen minimum zones (OMZs), all surface phytoplankton groups, regardless of size, disappear and are replaced by unique cyanobacteria lineages below the oxycline. To develop reasonable hypotheses to explain this pattern, we conduct a review of available information on OMZ phytoplankton, and we re-analyze previously published data (flow cytometric and hydrographic) on vertical structure of phytoplankton communities in relation to light and O2 levels. We also review the physical constraints on O2 acquisition as well as O2-dependent metabolisms in phototrophs. These considerations, along with estimates of the photosynthetic capacity of phytoplankton along OMZ depth profiles using published data, suggest that top-down grazing, respiratory demand, and irradiance are insufficient to fully explain the vertical structure observed in the upper, more sunlit portions of OMZs. Photorespiration and water–water cycles are O2-dependent pathways with low O2 affinities. Although their metabolic roles are still poorly understood, a hypothetical dependence on such pathways by the phytoplankton adapted to the oxic ocean might explain vertical patterns in OMZs and results of laboratory experiments. This can be represented in a simple model in which the requirement for photorespiration in surface phytoplankton and O2-inhibition of OMZ lineages reproduces the observed vertical fluorescence profiles and the replacement of phytoplankton adapted to O2 by lineages restricted to the most O2-deficient waters. A high O2 requirement by modern phytoplankton would suggest a positive feedback that intensifies trends in OMZ extent and ocean oxygenation or deoxygenation, both in Earth's past and in response to current climate change.
- Published
- 2023
17. Impacts of reduced inorganic N:P ratio on three distinct plankton communities in the Humboldt upwelling system
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Spilling, Kristian, Camarena-Gómez, Maria-Teresa, Lipsewers, Tobias, Martinez-Varela, Alícia, Díaz-Rosas, Francisco, Eronen-Rasimus, Eeva, Silva, Nelson, von Dassow, Peter, and Montecino, Vivian
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- 2019
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18. Correction to: Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta
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Patil, Shrikant, Moeys, Sara, von Dassow, Peter, Huysman, Marie J. J., Mapleson, Daniel, De Veylder, Lieven, Sanges, Remo, Vyverman, Wim, Montresor, Marina, and Ferrante, Maria Immacolata
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- 2019
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19. Strength in numbers: Collaborative science for new experimental model systems.
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Ross F Waller, Phillip A Cleves, Maria Rubio-Brotons, April Woods, Sara J Bender, Virginia Edgcomb, Eric R Gann, Adam C Jones, Leonid Teytelman, Peter von Dassow, Steven W Wilhelm, and Jackie L Collier
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Biology (General) ,QH301-705.5 - Abstract
Our current understanding of biology is heavily based on a small number of genetically tractable model organisms. Most eukaryotic phyla lack such experimental models, and this limits our ability to explore the molecular mechanisms that ultimately define their biology, ecology, and diversity. In particular, marine protists suffer from a paucity of model organisms despite playing critical roles in global nutrient cycles, food webs, and climate. To address this deficit, an initiative was launched in 2015 to foster the development of ecologically and taxonomically diverse marine protist genetic models. The development of new models faces many barriers, some technical and others institutional, and this often discourages the risky, long-term effort that may be required. To lower these barriers and tackle the complexity of this effort, a highly collaborative community-based approach was taken. Herein, we describe this approach, the advances achieved, and the lessons learned by participants in this novel community-based model for research.
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- 2018
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20. Publisher Correction: Genetic tool development in marine protists: emerging model organisms for experimental cell biology
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Faktorová, Drahomíra, Nisbet, R. Ellen R., Fernández Robledo, José A., Casacuberta, Elena, Sudek, Lisa, Allen, Andrew E., Ares, Jr, Manuel, Aresté, Cristina, Balestreri, Cecilia, Barbrook, Adrian C., Beardslee, Patrick, Bender, Sara, 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, Docampo, Roberto, Dupont, Christopher L., Edgcomb, Virginia, Einarsson, 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., Jason Smith, G., 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, Woods, April, Zhang, Huan, Mock, Thomas, Worden, Alexandra Z., and Lukeš, Julius
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- 2020
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21. Biological oceanography, biogeochemical cycles, and pelagic ecosystem functioning of the east-central South Pacific Gyre: focus on Easter Island and Salas y Gómez Island
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Peter von Dassow and Silvana Collado-Fabbri
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Isla de Pascua ,Isla Salas y Gómez ,oceanografía ,comunidad planctónica ,función biogeoquímica ,ecosistema pelágico ,Aquaculture. Fisheries. Angling ,SH1-691 ,Oceanography ,GC1-1581 ,Biology (General) ,QH301-705.5 - Abstract
The Exclusive Economic Zone of Chile defined by Easter Island and Salas y Gómez Island is in the South Pacific Sub-tropical Gyre (SPSG), putting it at the center of the most oligotrophic and biomass poor waters in the world. Only 10 biological oceanographic expeditions have entered this zone in 105 years (19052010). We review key aspects of the plankton ecosystem and biogeochemical function relevant for the understanding of and conservation planning for marine environments. Plankton production is limited by lack of dissolved inorganic fixed nitrogen, not phosphorous. Higher organic nitrogen levels might be biologically unavailable. Short-term experiments suggested iron is not limiting, yet iron still likely limits nitrogen fixation, and thus production, at longer time scales, as the presence of nitrogen-fixers is exceptionally low compared to other ocean gyres. Plankton function is dominated by the smallest unicellular organisms, picoplankton (
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- 2014
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22. Correction to: Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta
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Shrikant Patil, Sara Moeys, Peter von Dassow, Marie J. J. Huysman, Daniel Mapleson, Lieven De Veylder, Remo Sanges, Wim Vyverman, Marina Montresor, and Maria Immacolata Ferrante
- Subjects
Biotechnology ,TP248.13-248.65 ,Genetics ,QH426-470 - Abstract
Following the publication of this article [1], the authors reported that the link to Additional file 11 linked to the wrong set of data. The correct supplementary data is provided in this Correction article (Additional file 11).
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- 2019
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23. Alteration of sexual reproduction and genetic diversity in the kelp species Laminaria digitata at the southern limit of its range.
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Luz Valeria Oppliger, Peter von Dassow, Sarah Bouchemousse, Marine Robuchon, Myriam Valero, Juan A Correa, Stéphane Mauger, and Christophe Destombe
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Medicine ,Science - Abstract
Adaptation to marginal habitats at species range-limits has often been associated with parthenogenetic reproduction in terrestrial animals and plants. Laboratory observations have shown that brown algae exhibit a high propensity for parthenogenesis by various mechanisms. The kelp Laminaria digitata is an important component of the ecosystem in Northern European rocky intertidal habitats. We studied four L. digitata populations for the effects of marginality on genetic diversity and sexual reproduction. Two populations were marginal: One (Locquirec, in Northern Brittany) was well within the geographic range, but was genetically isolated from other populations by large stretches of sandy beaches. Another population was at the range limits of the species (Quiberon, in Southern Brittany) and was exposed to much higher seasonal temperature changes. Microsatellite analyses confirmed that these populations showed decreased genetic and allelic diversity, consistent with marginality and genetic isolation. Sporophytes from both marginal populations showed greatly diminished spore-production compared to central populations, but only the southern-limit population (Quiberon) showed a high propensity for producing unreduced (2N) spores. Unreduced 2N spores formed phenotypically normal gametophytes with nuclear area consistent with ≥2N DNA contents, and microsatellite studies suggested these were produced at least in part by automixis. However, despite this being the dominant path of spore production in Quiberon sporophyte individuals, the genetic evidence indicated the population was maintained mostly by sexual reproduction. Thus, although spore production and development showed the expected tendency of geographical parthenogenesis in marginal populations, this appeared to be a consequence of maladaptation, rather than an adaptation to, life in a marginal habitat.
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- 2014
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24. Biomechanics and the thermotolerance of development.
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Michelangelo von Dassow, Callie Johnson Miller, and Lance A Davidson
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Medicine ,Science - Abstract
Successful completion of development requires coordination of patterning events with morphogenetic movements. Environmental variability challenges this coordination. For example, developing organisms encounter varying environmental temperatures that can strongly influence developmental rates. We hypothesized that the mechanics of morphogenesis would have to be finely adjusted to allow for normal morphogenesis across a wide range of developmental rates. We formulated our hypothesis as a simple model incorporating time-dependent application of force to a viscoelastic tissue. This model suggested that the capacity to maintain normal morphogenesis across a range of temperatures would depend on how both tissue viscoelasticity and the forces that drive deformation vary with temperature. To test this model we investigated how the mechanical behavior of embryonic tissue (Xenopus laevis) changed with temperature; we used a combination of micropipette aspiration to measure viscoelasticity, electrically induced contractions to measure cellular force generation, and confocal microscopy to measure endogenous contractility. Contrary to expectations, the viscoelasticity of the tissues and peak contractile tension proved invariant with temperature even as rates of force generation and gastrulation movements varied three-fold. Furthermore, the relative rates of different gastrulation movements varied with temperature: the speed of blastopore closure increased more slowly with temperature than the speed of the dorsal-to-ventral progression of involution. The changes in the relative rates of different tissue movements can be explained by the viscoelastic deformation model given observed viscoelastic properties, but only if morphogenetic forces increase slowly rather than all at once.
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- 2014
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25. Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta
- Author
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Patil, Shrikant, Moeys, Sara, von Dassow, Peter, Huysman, Marie J. J., Mapleson, Daniel, De Veylder, Lieven, Sanges, Remo, Vyverman, Wim, Montresor, Marina, and Ferrante, Maria Immacolata
- Published
- 2015
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26. Control of Drosophila endocycles by E2F and CRL4CDT2
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Zielke, Norman, Kim, Kerry J., Tran, Vuong, Shibutani, Shusaku T., Bravo, Maria-Jose, Nagarajan, Sabarish, van Straaten, Monique, Woods, Brigitte, von Dassow, George, Rottig, Carmen, Lehner, Christian F., Grewal, Savraj S., Duronio, Robert J., and Edgar, Bruce A.
- Published
- 2011
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27. Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO2: from physiology to molecular level
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Richier, Sophie, Fiorini, Sarah, Kerros, Marie-Emmanuelle, von Dassow, Peter, and Gattuso, Jean-Pierre
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- 2011
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28. Over-calcified forms of the coccolithophore Emiliania huxleyi in high-CO2 waters are not preadapted to ocean acidification
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Von Dassow, P, Díaz-Rosas, F, Bendif, E, Gaitán-Espitia, J, Mella-Flores, D, Rokitta, S, John, U, Torres, R, Evolutionary Biology and Ecology of Algae (EBEA), Station biologique de Roscoff [Roscoff] (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Universidad Austral de Chile-Centre National de la Recherche Scientifique (CNRS)-Pontificia Universidad Católica de Chile (UC), Pontificia Universidad Católica de Chile (UC), University of Oxford [Oxford], Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), and Centro de Investigación en Ecosistemas de la Patagonia - Universidad Austral de Chile (CIEP)
- Subjects
fungi ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology ,[SDV.EE.BIO]Life Sciences [q-bio]/Ecology, environment/Bioclimatology - Abstract
Marine multicellular organisms inhabiting waters with natural high fluctuations in pH appear more tolerant to acidification than conspecifics occurring in nearby stable waters, suggesting that environments of fluctuating pH hold genetic reservoirs for adaptation of key groups to ocean acidification (OA). The abundant and cosmopolitan calcifying phytoplankton Emiliania huxleyi exhibits a range of morphotypes with varying degrees of coccolith mineralization. We show that E. huxleyi populations in the naturally acidified upwelling waters of the eastern South Pacific, where pH drops below 7.8 as is predicted for the global surface ocean by the year 2100, are dominated by exceptionally over-calcified morphotypes whose distal coccolith shield can be almost solid calcite. Shifts in morphotype composition of E. huxleyi populations correlate with changes in carbonate system parameters. We tested if these correlations indicate that the hyper-calcified morphotype is adapted to OA. In experimental exposures to present-day vs. future pCO2 (400 vs. 1200 µatm), the over-calcified morphotypes showed the same growth inhibition (−29.1±6.3 %) as moderately calcified morphotypes isolated from non-acidified water (−30.7±8.8 %). Under the high-CO2–low-pH condition, production rates of particulate organic carbon (POC) increased, while production rates of particulate inorganic carbon (PIC) were maintained or decreased slightly (but not significantly), leading to lowered PIC ∕ POC ratios in all strains. There were no consistent correlations of response intensity with strain origin. The high-CO2–low-pH condition affected coccolith morphology equally or more strongly in over-calcified strains compared to moderately calcified strains. High-CO2–low-pH conditions appear not to directly select for exceptionally over-calcified morphotypes over other morphotypes, but perhaps indirectly by ecologically correlated factors. More generally, these results suggest that oceanic planktonic microorganisms, despite their rapid turnover and large population sizes, do not necessarily exhibit adaptations to naturally high-CO2 upwellings, and this ubiquitous coccolithophore may be near the limit of its capacity to adapt to ongoing ocean acidification.
- Published
- 2020
29. Surprisingly simple mechanical behavior of a complex embryonic tissue.
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Michelangelo von Dassow, James A Strother, and Lance A Davidson
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Medicine ,Science - Abstract
Previous studies suggest that mechanical feedback could coordinate morphogenetic events in embryos. Furthermore, embryonic tissues have complex structure and composition and undergo large deformations during morphogenesis. Hence we expect highly non-linear and loading-rate dependent tissue mechanical properties in embryos.We used micro-aspiration to test whether a simple linear viscoelastic model was sufficient to describe the mechanical behavior of gastrula stage Xenopus laevis embryonic tissue in vivo. We tested whether these embryonic tissues change their mechanical properties in response to mechanical stimuli but found no evidence of changes in the viscoelastic properties of the tissue in response to stress or stress application rate. We used this model to test hypotheses about the pattern of force generation during electrically induced tissue contractions. The dependence of contractions on suction pressure was most consistent with apical tension, and was inconsistent with isotropic contraction. Finally, stiffer clutches generated stronger contractions, suggesting that force generation and stiffness may be coupled in the embryo.The mechanical behavior of a complex, active embryonic tissue can be surprisingly well described by a simple linear viscoelastic model with power law creep compliance, even at high deformations. We found no evidence of mechanical feedback in this system. Together these results show that very simple mechanical models can be useful in describing embryo mechanics.
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- 2010
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30. Evidence for shear-induced increase in membrane fluidity in the dinoflagellate Lingulodinium polyedrum
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Mallipattu, S., Haidekker, M., Von Dassow, P., Latz, M., and Frangos, J.
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- 2002
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31. Multi-Purpose Berry Bowls.
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von Dassow, Sumi
- Subjects
BERRIES ,SOUR cherry ,FRUIT juices ,GLAZES ,COCONUT milk - Abstract
The article provides instructions on how to make a multi-purpose berry bowl, with a saucer to avoid water puddles, by using clay and pottery-making techniques. The process involves throwing and trimming the bowl, throwing the saucer, drilling the drainage holes, and cleaning the bowl. A berry bowl can be used as a colander for draining noodles, as a fruit bowl, and as a steamer for vegetables.
- Published
- 2023
32. Relationships between growth, morphology and wall stress in the stalk of Acetabularia acetabulum
- Author
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von Dassow, Michelangelo, Odell, Garret M., and Mandoli, Dina F.
- Published
- 2001
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33. Genome size differentiates co-occurring populations of the planktonic diatom Ditylum brightwellii (Bacillariophyta)
- Author
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von Dassow Peter, Swalwell Jarred E, Koester Julie A, and Armbrust E Virginia
- Subjects
Evolution ,QH359-425 - Abstract
Abstract Background Diatoms are one of the most species-rich groups of eukaryotic microbes known. Diatoms are also the only group of eukaryotic micro-algae with a diplontic life history, suggesting that the ancestral diatom switched to a life history dominated by a duplicated genome. A key mechanism of speciation among diatoms could be a propensity for additional stable genome duplications. Across eukaryotic taxa, genome size is directly correlated to cell size and inversely correlated to physiological rates. Differences in relative genome size, cell size, and acclimated growth rates were analyzed in isolates of the diatom Ditylum brightwellii. Ditylum brightwellii consists of two main populations with identical 18s rDNA sequences; one population is distributed globally at temperate latitudes and the second appears to be localized to the Pacific Northwest coast of the USA. These two populations co-occur within the Puget Sound estuary of WA, USA, although their peak abundances differ depending on local conditions. Results All isolates from the more regionally-localized population (population 2) possessed 1.94 ± 0.74 times the amount of DNA, grew more slowly, and were generally larger than isolates from the more globally distributed population (population 1). The ITS1 sequences, cell sizes, and genome sizes of isolates from New Zealand were the same as population 1 isolates from Puget Sound, but their growth rates were within the range of the slower-growing population 2 isolates. Importantly, the observed genome size difference between isolates from the two populations was stable regardless of time in culture or the changes in cell size that accompany the diatom life history. Conclusions The observed two-fold difference in genome size between the D. brightwellii populations suggests that whole genome duplication occurred within cells of population 1 ultimately giving rise to population 2 cells. The apparent regional localization of population 2 is consistent with a recent divergence between the populations, which are likely cryptic species. Genome size variation is known to occur in other diatom genera; we hypothesize that genome duplication may be an active and important mechanism of genetic and physiological diversification and speciation in diatoms.
- Published
- 2010
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34. Identification of the meiotic toolkit in diatoms and exploration of meiosis-specific SPO11 and RAD51 homologs in the sexual species Pseudo-nitzschia multistriata and Seminavis robusta
- Author
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Patil, S., Moeys, S., von Dassow, P., Huysman, M.J.J., Mapleson, D., De Veylder, L., Sanges, R., Vyverman, W., Montresor, M., and Ferrante, M.I.
- Subjects
fungi ,Bacillariophyceae [Featherlike diatoms] - Abstract
BackgroundSexual reproduction is an obligate phase in the life cycle of most eukaryotes. Meiosis varies among organisms, which is reflected by the variability of the gene set associated to the process. Diatoms are unicellular organisms that belong to the stramenopile clade and have unique life cycles that can include a sexual phase.ResultsThe exploration of five diatom genomes and one diatom transcriptome led to the identification of 42 genes potentially involved in meiosis. While these include the majority of known meiosis-related genes, several meiosis-specific genes, including DMC1, could not be identified. Furthermore, phylogenetic analyses supported gene identification and revealed ancestral loss and recent expansion in the RAD51 family in diatoms. The two sexual species Pseudo-nitzschia multistriata and Seminavis robusta were used to explore the expression of meiosis-related genes: RAD21, SPO11-2, RAD51-A, RAD51-B and RAD51-C were upregulated during meiosis, whereas other paralogs in these families showed no differential expression patterns, suggesting that they may play a role during vegetative divisions. An almost identical toolkit is shared among Pseudo-nitzschia multiseries and Fragilariopsis cylindrus, as well as two species for which sex has not been observed, Phaeodactylum tricornutum and Thalassiosira pseudonana, suggesting that these two may retain a facultative sexual phase.ConclusionsOur results reveal the conserved meiotic toolkit in six diatom species and indicate that Stramenopiles share major modifications of canonical meiosis processes ancestral to eukaryotes, with important divergences in each Kingdom.
- Published
- 2015
35. POCKET MUGS.
- Author
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von Dassow, Sumi
- Subjects
MUGS ,POLYVINYL chloride pipe - Abstract
The article presents step-by-step process for making pocket cups for holding the coffee mug more differently.
- Published
- 2020
36. The hydrodynamics and kinematics of the appendicularian tail underpin peristaltic pumping
- Author
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Hiebert, Terra C., Gemmell, Brad J., von Dassow, George, Conley, Keats R., and Sutherland, Kelly R.
- Abstract
Planktonic organisms feed while suspended in water using various hydrodynamic pumping strategies. Appendicularians are a unique group of plankton that use their tail to pump water over mucous mesh filters to concentrate food particles. As ubiquitous and often abundant members of planktonic ecosystems, they play a major role in oceanic food webs. Yet, we lack a complete understanding of the fluid flow that underpins their filtration. Using high-speed, high-resolution video and micro particle image velocimetry, we describe the kinematics and hydrodynamics of the tail in Oikopleura dioicain filtering and free-swimming postures. We show that sinusoidal waves of the tail generate peristaltic pumping within the tail chamber with fluid moving parallel to the tail when filtering. We find that the tail contacts attachment points along the tail chamber during each beat cycle, serving to seal the tail chamber and drive pumping. When we tested how the pump performs across environmentally relevant temperatures, we found that the amplitude of the tail was invariant but tail beat frequency increased threefold across three temperature treatments (5°C, 15°C and 25°C). Investigation into this unique pumping mechanism gives insight into the ecological success of appendicularians and provides inspiration for novel pump designs.
- Published
- 2023
- Full Text
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37. Pan genome of the phytoplankton Emiliania underpins its global distribution
- Author
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Read, B.A., Kegel, J., Klute, M.J., Kuo, A., Lefebvre, S.C., Maumus, F., Mayer, C., Miller, J., Monier, A., Salamov, A., Young, J., Aguilar, M., Claverie, J.-M., Frickenhaus, S., Gonzalez, K., Herman, E.K., Lin, Y.-C., Napier, J., Ogata, H., Sarno, A.F., Schmutz, J., Schroeder, D., de Vargas, C., Verret, F., von Dassow, P., Valentin, K., Van de Peer, Y., Wheeler, G., Emiliania huxleyi Annotation Consortium, Dacks, J.B., Delwiche, C.F., Dyhrman, S.T., Glöckner, G., John, U., Richards, T., Worden, A.Z., Zhang, X., and Grigoriev, I.V.
- Subjects
fungi - Abstract
Coccolithophores have influenced the global climate for over 200 million years. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space. Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO2 production or uptake, sequestration and export to the deep ocean. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions.
- Published
- 2013
38. The Ectocarpus genome and brown algal genomics
- Author
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Cock, J.M., Sterck, L., Ahmed, S., Allen, A. E., Amoutzias, G., Anthouard, V., Artiguenave, F., Arun, A., Aury, J. M., Badger, J. H., Beszteri, B., Billiau, K., Bonnet, E., Bothwell, J. H., Bowler, C., Boyen, C., Brownlee, C., Carrano, C. J., Charrier, B., Cho, G. Y., Coelho, S. M., Collen, J., Le Corguille, G., Corre, E., Dartevelle, L., Da Silva, C., Delage, L., Delaroque, N., Dittami, S. M., Doulbeau, Sylvie, Elias, M., Farnham, G., Gachon, C. M. M., Godfroy, O., Gschloessl, B., Heesch, S., Jabbari, K., Jubin, C., Kawai, H., Kimura, K., Kloareg, B., Kuepper, F. C., Lang, D., Le Bail, A., Luthringer, R., Leblanc, C., Lerouge, P., Lohr, M., Lopez, P. J., Macaisne, N., Martens, C., Maumus, F., Michel, G., Miranda-Saavedra, D., Morales, J., Moreau, H., Motomura, T., Nagasato, C., Napoli, C. A., Nelson, D. R., Nyvall-Collen, P., Peters, A. F., Pommier, C., Potin, P., Poulain, J., Quesneville, H., Read, B., Rensing, S.A., Ritter, A., Rousvoal, S., Samanta, M., Samson, G., Schroeder, D.C., Scornet, D., Segurens, B., Strittmatter, M., Tonon, T., Tregear, James, Valentin, K., Von Dassow, P., Yamagishi, T., Rouze, P., Van de Peer, Y., Wincker, P., and Piganeau, G. (ed.)
- Subjects
IRON-DEFICIENCY ,EVOLUTIONARY HISTORY ,PLANT MICRORNAS ,SILICULOSUS ,TOPOISOMERASE-VI ,fungi ,food and beverages ,DIATOM THALASSIOSIRA-PSEUDONANA ,PROTEIN FAMILY ,LAMINARIA-DIGITATA ,CHLAMYDOMONAS-REINHARDTII ,PHAEOPHYCEAE ,NORTH-ATLANTIC - Abstract
Brown algae are important organisms both because of their key ecological roles in coastal ecosystems and because of the remarkable biological features that they have acquired during their unusual evolutionary history. The recent sequencing of the complete genome of the filamentous brown alga Ectocarpus has provided unprecedented access to the molecular processes that underlie brown algal biology. Analysis of the genome sequence, which exhibits several unusual structural features, identified genes that are predicted to play key roles in several aspects of brown algal metabolism, in the construction of the multicellular bodyplan and in resistance to biotic and abiotic stresses. Information from the genome sequence is currently being used in combination with other genomic, genetic and biochemical tools to further investigate these and other aspects of brown algal biology at the molecular level. Here, we review some of the major discoveries that emerged from the analysis of the Ectocarpus genome sequence, with a particular focus on the unusual genome structure, inferences about brown algal evolution and novel aspects of brown algal metabolism.
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- 2012
39. The Ectocarpus genome and the independent evolution of multicellularity in brown algae
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Cock, J.M., Sterck, L., Rouzé, P., Scornet, D., Allen, A.E., Amoutzias, G., Anthouard, V., Artiguenave, F., Aury, J.-M., Badger, J.H., Beszteri, B., Billiau, K., Bonnet, E., Bothwell, J.H., Bowler, C., Boyen, C., Brownlee, C., Carrano, C.J., Charrier, B., Cho, G.Y., Coelho, S.M., Collén, J., Corre, E., Da Silva, C., Delage, L., Delaroque, N., Dittami, S.M., Doulbeau, S., Elias, M., Farnham, G., Gachon, C.M.M., Gschloessl, B., Heesch, S., Jabbari, K., Jubin, C., Kawai, H., Kimura, K., Kloareg, B., Küpper, F.C., Lang, D., Le Bail, A., Leblanc, C., Lerouge, P., Lohr, M., Lopez, P.J., Martens, C., Maumus, F., Michel, G., Miranda-Saavedra, D., Morales, J., Moreau, H., Motomura, T., Nagasato, C., Napoli, C.A., Nelson, D.R., Nyvall-Collén, P., Peters, A.F., Pommier, C., Potin, Ph., Poulain, J., Quesneville, H., Read, B., Rensing, S.A., Ritter, A., Rousvoal, S., Samanta, M., Samson, G., Schroeder, D.C., Segurens, B., Strittmatter, M., Tonon, T., Tregear, J.W., Valentin, K., von Dassow, P., Yamagishi, T., Van de Peer, Y., and Wincker, P.
- Abstract
Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related1. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. Brown algae are also one of only a small number of eukaryotic lineages that have evolved complex multicellularity (Fig. 1).We report the 214 million base pair (Mbp) genome sequence of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for brown algae, closely related to the kelps (Fig. 1). Genome features such as the presence of an extended set of light-harvesting and pigment biosynthesis genes and new metabolic processes such as halide metabolism help explain the ability of this organism to cope with the highly variable tidal environment. The evolution of multicellularity in this lineage is correlated with the presence of a rich array of signal transduction genes. Of particular interest is the presence of a family of receptor kinases, as the independent evolution of related molecules has been linked with the emergence of multicellularity in both the animal and green plant lineages. The Ectocarpus genome sequence represents an important step towards developing this organism as a model species, providing the possibility to combine genomic and genetic2 approaches to explore these and other aspects of brown algal biology further.
- Published
- 2010
40. Inter- and intraspecific relationships between nuclear DNA content and cell size in selected members of the centric diatom genus Thalassiosira (Bacillariophyceae)
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von Dassow, P., Petersen, T.W., Chepurnov, V.A., and Armbrust, E.V.
- Subjects
fungi - Abstract
The enormous species diversity of diatoms correlates with the remarkable range of cell sizes in this group. Nuclear DNA content relates fundamentally to cell volume in other eukaryotic cells. The relationship of cell volume to G1 DNA content was determined among selected members of the genus Thalassiosira, one of the most species-rich and well-studied centric diatom genera. Both minimum and maximum species-specific cell volume correlated positively with G1 DNA content. Phylogeny based on 5.8 S and ITS rDNA sequences indicated that multiple changes in G1 DNA content and cell volume occurred in Thalassiosira evolution, leading to a 1,000-fold range in both parameters in the group. Within the Thalassiosira weissflogii (Grunow) G. A. Fryxell et Grunow species complex, G1 DNA content varied 3-fold: differences related to geographic origin and time since isolation; doubling and tripling of G1 DNA content occurred since isolation in certain T. weissflogii isolates; and subcultures of T. weissflogii CCMP 1336 diverged in DNA content by 50% within 7 years of separation. Actin, beta-tubulin, and Spo11/TopVIA genes were selected for quantitative PCR estimation of haploid genome size in subclones of selected T. weissflogii isolates because they occur only once in the T. pseudonana Hasle et Heimdal genome. Comparison of haploid genome size estimates with G1 DNA content suggested that the most recent T. weissflogii isolate was diploid, whereas other T. weissflogii isolates appeared to be polyploid and/or aneuploid. Aberrant meiotic and mitotic cell divisions were observed, which might relate to polyploidization. The structural flexibility of diatom genomes has important implications for their evolutionary diversification and stability during laboratory maintenance.
- Published
- 2008
41. The Phaeodactylum genome reveals the evolutionary history of diatom genomes
- Author
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Bowler, C., Allan, A. E., Badger, J. H., Grimwood, J., Jabbari, K., Kuo, A., Maheshwari, U., Martens, C., Maumus, F., Otillar, R. P., Rayko, E., Salamov, A., Vandepoele, K., Beszeri, B., Gruber, A., Heijde, M., Katinka, M., Mock, Thomas, Valentin, Klaus-Ulrich, Verret, F., Berges, J. A., Brownlee, C., Chiovitti, A., Jae Choi, C., Coesel, S., De Martino, A., Detter, J. C., Durkin, C., Falciatore, A., Fournet, J., Haruta, M., Huysman, M. J. J., Jenkins, B. D., Jiroutova, K., Jorgensen, R. E., Joubert, Y., Kaplan, A., Kröger, N., Kroth, P. G., La Roche, J., Lindquiste, E., Lommer, M., Martin-Jézéquel, V., Lopez, P. J., Lucas, S., Mangogna, M., McGinnis, K., Medlin, Linda, Monsant, A., Oudot-Le Secq, M.-P., Napoli, C., Obornik, M., Petit, J.-L., Porcel, B. M., Poulsen, N., Robison, M., Rychlewski, L., Rynearson, T. A., Schmutz, J., Schnitzler Parker, M., Shapiro, H., Siaur, M., Stanley, M., Sussman, M. J., Taylor, A. R., Vardi, A., von Dassow, P., Vyverman, W., Willis, A., Wyrwicz, L. S., Rokhsar, D. S., Weissenbach, J., Armbrust, E. V., Green, B. R., Van de Peer, Y., Grigoriev, I. V., and Cadoret, J.-P.
- Published
- 2008
42. In search of new tractable diatoms for experimental biology
- Author
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Chepurnov, V.A., Mann, D.G., von Dassow, P., Vanormelingen, P., Gillard, J., Inzé, D., Sabbe, K., and Vyverman, W.
- Abstract
Diatoms are a species-rich group of photosynthetic eukaryotes, with enormous ecological significance and great potential for biotechnology. During the last decade, diatoms have begun to be studied intensively using modern molecular techniques and the genomes of four diatoms have been wholly or partially sequenced. Although new insights into the biology and evolution of diatoms are accumulating rapidly due to the availability of reverse genetic tools, the full potential of these molecular biological approaches can only be fully realized if experimental control of sexual crosses becomes firmly established and widely accessible to experimental biologists. Here we discuss the issue of choosing new models for diatom research, by taking into account the broader context of diatom mating systems and the place of sex in relation to the intricate cycle of cell size reduction and restitution that is characteristic of most diatoms. We illustrate the results of our efforts to select and develop experimental systems in diatoms, using species with typical life cycle attributes, which could be used as future model organisms to complement existing ones
- Published
- 2008
43. Oogamous reproduction, with two-step auxosporulation, in the centric diatom Thalassiosira punctigera (Bacillariophyta)
- Author
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Chepurnov, V.A., Mann, D.G., von Dassow, P., Armbrust, E.V., Sabbe, K., Dasseville, R., and Vyverman, W.
- Subjects
Mating ,Sexual reproduction ,Bacillariophyceae [Featherlike diatoms] ,Thalassiosira ,ANE, Netherlands, Westerschelde, Terneuzen - Abstract
Thalassiosira species are common components of marine planktonic communities worldwide and are used intensively as model experimental organisms. However, data on life cycles and sexuality within the genus are fragmentary. A clone of the cosmopolitan marine diatom Thalassiosira punctigera Cleve emend. Hasle was isolated from the North Sea and oogamous sexual reproduction was observed in culture. Cells approximately 45 µm and smaller became sexualized. Oogonia were produced preferentially and spermatogenesis was infrequent. Unfertilized oogonia always aborted and their development was apparently arrested at prophase of meiosis I. Further progression through meiosis and auxospore formation occurred only after a sperm had penetrated into the oocyte. Many cells of the new large-celled generation (approximately 90–120 µm in size) immediately became sexualized again but only oogonia were produced. A few of the large oogonia became auxospores and produced initial cells 132–153 µm in diameter. The second step of auxosporulation probably involved fertilization of large-celled oocytes by the sperm of the small-celled spermatogonangia that were still present in the culture. An F1 clone obtained after selfing within the small-celled auxosporulation size range was investigated. Like the parent clone, the F1 clone was homothallic but no auxosporulation was observed: spermatogonangia were unable to produce viable sperm, apparently because of inbreeding depression. Aggregation and interaction of oogonia were documented, and may be relevant for understanding the mechanisms of signaling and recognition between sexualized cells and the evolution of sexuality in pennate diatoms.
- Published
- 2006
44. Making Rice-Paper Transfers.
- Author
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von Dassow, Sumi
- Subjects
SILK screen printing ,EMULSION paint ,POTTERY ,CORPORATE bonds ,PAINTBRUSHES - Abstract
The article offers step-by-step instructions for making rice-paper transfers.
- Published
- 2020
45. People Feeder.
- Author
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von Dassow, Sumi
- Subjects
POTTERY - Abstract
The article offers step-by-step instruction for making pot called people feeder to be used in party and public gatherings.
- Published
- 2020
46. Pan genome of the phytoplankton Emiliania underpins its global distribution
- Author
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Read, B. A., Kegel, J., Klute, M. J., Kuo, A., Lefebvre, S. C., Maumus, F., Mayer, C., Miller, J., Monier, A., Salamov, A., Young, J., Aguilar, M., Claverie, J.-M., Frickenhaus, S., Gonzalez, K., Herman, E. K., Lin, Y.-C., Napier, J., Ogata, H., Sarno, A. F., Shmutz, J., Schroeder, D., De Vargas, C., Verret, F., Von Dassow, P., Valentin, K., Van De Peer, Y., Wheeler, G., Dacks, J. B., Delwiche, C. F., Dyhrman, S. T., Glöckner, G., John, U., Richards, T., Worden, Alexandra Z., Zhang, X., Grigoriev, I. V., Allen, A. E., Bidle, K., Borodovsky, M., Bowler, C., Brownlee, C., Mark Cock, J., Elias, M., Gladyshev, V. N., Groth, M., Guda, C., Hadaegh, A., Iglesias-Rodriguez, M. D., Jenkins, J., Jones, B. M., Lawson, T., Leese, F., Lindquist, E., Lobanov, A., Lomsadze, A., Malik, S.-B., Marsh, M. E., MacKinder, L., Mock, T., Mueller-Roeber, B., Pagarete, A., Parker, M., Probert, I., Quesneville, H., Raines, C., Rensing, S. A., Riaño-Pachón, D. M., Richier, S., Rokitta, S., Shiraiwa, Y., Soanes, D. M., Van Der Giezen, M., Wahlund, T. M., Williams, B., Wilson, W., Wolfe, G., Wurch, L. L., Read, B. A., Kegel, J., Klute, M. J., Kuo, A., Lefebvre, S. C., Maumus, F., Mayer, C., Miller, J., Monier, A., Salamov, A., Young, J., Aguilar, M., Claverie, J.-M., Frickenhaus, S., Gonzalez, K., Herman, E. K., Lin, Y.-C., Napier, J., Ogata, H., Sarno, A. F., Shmutz, J., Schroeder, D., De Vargas, C., Verret, F., Von Dassow, P., Valentin, K., Van De Peer, Y., Wheeler, G., Dacks, J. B., Delwiche, C. F., Dyhrman, S. T., Glöckner, G., John, U., Richards, T., Worden, Alexandra Z., Zhang, X., Grigoriev, I. V., Allen, A. E., Bidle, K., Borodovsky, M., Bowler, C., Brownlee, C., Mark Cock, J., Elias, M., Gladyshev, V. N., Groth, M., Guda, C., Hadaegh, A., Iglesias-Rodriguez, M. D., Jenkins, J., Jones, B. M., Lawson, T., Leese, F., Lindquist, E., Lobanov, A., Lomsadze, A., Malik, S.-B., Marsh, M. E., MacKinder, L., Mock, T., Mueller-Roeber, B., Pagarete, A., Parker, M., Probert, I., Quesneville, H., Raines, C., Rensing, S. A., Riaño-Pachón, D. M., Richier, S., Rokitta, S., Shiraiwa, Y., Soanes, D. M., Van Der Giezen, M., Wahlund, T. M., Williams, B., Wilson, W., Wolfe, G., and Wurch, L. L.
- Abstract
Coccolithophores have influenced the global climate for over 200 million years. These marine phytoplankton can account for 20 per cent of total carbon fixation in some systems. They form blooms that can occupy hundreds of thousands of square kilometres and are distinguished by their elegantly sculpted calcium carbonate exoskeletons (coccoliths), rendering them visible from space. Although coccolithophores export carbon in the form of organic matter and calcite to the sea floor, they also release CO 2 in the calcification process. Hence, they have a complex influence on the carbon cycle, driving either CO 2 production or uptake, sequestration and export to the deep ocean. Here we report the first haptophyte reference genome, from the coccolithophore Emiliania huxleyi strain CCMP1516, and sequences from 13 additional isolates. Our analyses reveal a pan genome (core genes plus genes distributed variably between strains) probably supported by an atypical complement of repetitive sequence in the genome. Comparisons across strains demonstrate that E. huxleyi, which has long been considered a single species, harbours extensive genome variability reflected in different metabolic repertoires. Genome variability within this species complex seems to underpin its capacity both to thrive in habitats ranging from the equator to the subarctic and to form large-scale episodic blooms under a wide variety of environmental conditions. © 2013 Macmillan Publishers Limited. All rights reserved.
- Published
- 2013
- Full Text
- View/download PDF
47. Response of the calcifying coccolithophore Emiliania huxleyi to low pH/high pCO2: from physiology to molecular level
- Author
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Richier, S., Fiorini, S., Kerros, M.E., von Dassow, P., Gattuso, J.P., Richier, S., Fiorini, S., Kerros, M.E., von Dassow, P., and Gattuso, J.P.
- Abstract
The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO2 in the widespread and abundant coccolithophore Emiliania huxleyi. Batch cultures were subjected to increased partial pressure of CO2 (pCO2; i.e. decreased pH), and the changes in expression of four functional gene classes directly or indirectly related to calcification were investigated. Increased pCO2 did not affect the calcification rate and only carbonic anhydrase transcripts exhibited a significant down-regulation. Our observation that elevated pCO2 induces only limited changes in the transcription of several transporters of calcium and bicarbonate gives new significant elements to understand cellular mechanisms underlying the early response of E. huxleyi to CO2-driven ocean acidification., The emergence of ocean acidification as a significant threat to calcifying organisms in marine ecosystems creates a pressing need to understand the physiological and molecular mechanisms by which calcification is affected by environmental parameters. We report here, for the first time, changes in gene expression induced by variations in pH/pCO2 in the widespread and abundant coccolithophore Emiliania huxleyi. Batch cultures were subjected to increased partial pressure of CO2 (pCO2; i.e. decreased pH), and the changes in expression of four functional gene classes directly or indirectly related to calcification were investigated. Increased pCO2 did not affect the calcification rate and only carbonic anhydrase transcripts exhibited a significant down-regulation. Our observation that elevated pCO2 induces only limited changes in the transcription of several transporters of calcium and bicarbonate gives new significant elements to understand cellular mechanisms underlying the early response of E. huxleyi to CO2-driven ocean acidification.
- Published
- 2011
48. The Ectocarpus genome and the independent evolution of multicellularity in the brown algae
- Author
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Cock, J. M., Sterck, L., Rouze, P., Scorne, D., Allen, A. E., Amoutzias, G., Anthouard, V., Artiguenave, F., Aury, J. M., Badger, J. H., Beszteri, Bank, Billiau, K., Bonnet, E., Bothwell, J. H. F., Bowler, C., Boyen, C., Brownlee, C., Carrano, C. J., Charrier, B., Youn Cho, G., Coelho, S. M., Collén, J., Corre, E., Da Silva, C., Delage, L., Delaroque, N., Dittami, S. M., Doulbeau, S., Elias, M., Farnham, C., Gachon, C. M. M., Gschloessl, B., Heesch, S., Jabbari, K., Jubin, C., Kawai, H., Kimura, K., Kloareg, B., Küpper, F. C., Lang, D., Le Bail, A., Leblan, C., Lerouge, P., Lohr, M., López-González, P. J., Martens, C., Maumus, F., Michel, G., Miranda-Saavedra, D., Morales, J., Moreau, H., Motomura, T., Nagasato, C., Napoli, C. A., Nelson, D. R., Nyvall-Collén, Pi, Peters, A. F., Pommier, C., Potin, P., Poulain, J., Quesneville, H., Read, B., Rensing, S. A., Ritter, A., Rousvoal, S., Samanta, M., Samson, G., Schroeder, D. C., Séguren, B., Strittmatter, M., Tonon, T., Tregear, J., Valentin, Klaus-Ulrich, von Dassow, P., Yamagishi, T., Van de Peer, Y., Wincker, P., Cock, J. M., Sterck, L., Rouze, P., Scorne, D., Allen, A. E., Amoutzias, G., Anthouard, V., Artiguenave, F., Aury, J. M., Badger, J. H., Beszteri, Bank, Billiau, K., Bonnet, E., Bothwell, J. H. F., Bowler, C., Boyen, C., Brownlee, C., Carrano, C. J., Charrier, B., Youn Cho, G., Coelho, S. M., Collén, J., Corre, E., Da Silva, C., Delage, L., Delaroque, N., Dittami, S. M., Doulbeau, S., Elias, M., Farnham, C., Gachon, C. M. M., Gschloessl, B., Heesch, S., Jabbari, K., Jubin, C., Kawai, H., Kimura, K., Kloareg, B., Küpper, F. C., Lang, D., Le Bail, A., Leblan, C., Lerouge, P., Lohr, M., López-González, P. J., Martens, C., Maumus, F., Michel, G., Miranda-Saavedra, D., Morales, J., Moreau, H., Motomura, T., Nagasato, C., Napoli, C. A., Nelson, D. R., Nyvall-Collén, Pi, Peters, A. F., Pommier, C., Potin, P., Poulain, J., Quesneville, H., Read, B., Rensing, S. A., Ritter, A., Rousvoal, S., Samanta, M., Samson, G., Schroeder, D. C., Séguren, B., Strittmatter, M., Tonon, T., Tregear, J., Valentin, Klaus-Ulrich, von Dassow, P., Yamagishi, T., Van de Peer, Y., and Wincker, P.
- Published
- 2010
49. Green evolution and dynamic adaptations revealed by genomes of the marine picoeukaryotes micromonas
- Author
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Worden, Alexandra Z., Lee, J.-H., Mock, T., Rouzé, P., Simmons, M. P., Aerts, A. L., Allen, A. E., Cuvelier, M. L., Derelle, E., Everett, M. V., Foulon, E., Grimwood, J., Gundlach, H., Henrissat, B., Napoli, C., McDonald, S. M., Parker, M. S., Rombauts, S., Salamov, A., Von Dassow, P., Badger, J. H., Coutinho, P. M., Demir, E., Dubchak, I., Gentemann, C., Eikrem, W., Gready, J. E., John, U., Lanier, W., Lindquist, E. A., Lucas, S., Mayer, K. F. X., Moreau, H., Not, F., Otillar, R., Panaud, O., Pangilinan, J., Paulsen, I., Piegu, B., Poliakov, A., Robbens, S., Schmutz, J., Toulza, E., Wyss, T., Zelensky, A., Zhou, K., Armbrust, E. V., Bhattacharya, D., Goodenough, U. W., Van De Peer, Y., Grigoriev, I.V., Worden, Alexandra Z., Lee, J.-H., Mock, T., Rouzé, P., Simmons, M. P., Aerts, A. L., Allen, A. E., Cuvelier, M. L., Derelle, E., Everett, M. V., Foulon, E., Grimwood, J., Gundlach, H., Henrissat, B., Napoli, C., McDonald, S. M., Parker, M. S., Rombauts, S., Salamov, A., Von Dassow, P., Badger, J. H., Coutinho, P. M., Demir, E., Dubchak, I., Gentemann, C., Eikrem, W., Gready, J. E., John, U., Lanier, W., Lindquist, E. A., Lucas, S., Mayer, K. F. X., Moreau, H., Not, F., Otillar, R., Panaud, O., Pangilinan, J., Paulsen, I., Piegu, B., Poliakov, A., Robbens, S., Schmutz, J., Toulza, E., Wyss, T., Zelensky, A., Zhou, K., Armbrust, E. V., Bhattacharya, D., Goodenough, U. W., Van De Peer, Y., and Grigoriev, I.V.
- Abstract
Picoeukaryotes are a taxonomically diverse group of organism less than 2 micrometers in diameter. Photosynthetic marine picoeukaryotes in the genus Micromonas thrive in ecosystems ranging from tropical to polar and could serve as sentinel organisms for biogeochemical fluxes of modern oceans during climate change. These broadly distributed primary producers belong to an anciently diverged sister clade to land plants. Although Micromonas isolates have high 18S ribosomal RNA gene identity, we found that genomes from two isolates shared only 90 of their predicted genes. Their independent evolutionary paths were emphasized by distinct riboswitch arrangements as well as the discovery of intronic repeat elements in one isolate, and in metagenomic data, but not in other genomes. Divergence appears to have been facilitated by selection and acquisition processes that actively shape the repertoire of genes that are mutually exclusive between the two isolates differently than the core genes. Analyses of the Micromonas genomes offer valuable insights into ecological differentiation and the dynamic nature of early plant evolution.
- Published
- 2009
- Full Text
- View/download PDF
50. The Phaeodactylum genome reveals the evolutionary history of diatom genomes
- Author
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Bowler, C, Allen, A, Badger, J, Grimwood, J, Jabbari, K, Kuo, A, Maheswari, U, Martens, C, Maumus, F, Otillar, R, Rayko, E, Salamov, A, Vandepoele, K, Beszteri, B, Gruber, A, Heijde, M, Katinka, M, Mock, T, Valentin, K, Verret, F, Berges, J, Brownlee, C, Cadoret, Jean-paul, Chiovitti, A, Choi, C, Coesel, S, De Martino, A, Detter, J, Durkin, C, Falciatore, A, Fournet, J, Haruta, M, Huysman, M, Jenkins, B, Jiroutova, K, Jorgensen, R, Joubert, Y, Kaplan, A, Kroger, N, Kroth, P, La Roche, J, Lindquist, E, Lommer, M, Martin Jezequel, V, Lopez, P, Lucas, S, Mangogna, M, Mcginnis, K, Medlin, L, Montsant, A, Oudot Le Secq, M, Napoli, C, Obornik, M, Parker, M, Petit, J, Porcel, B, Poulsen, N, Robison, M, Rychlewski, L, Rynearson, T, Schmutz, J, Shapiro, H, Siaut, M, Stanley, M, Sussman, M, Taylor, A, Vardi, A, Von Dassow, P, Vyverman, W, Willis, A, Wyrwicz, L, Rokhsar, D, Weissenbach, J, Armbrust, E, Green, B, Van De Peer, Y, Grigoriev Iv, Bowler, C, Allen, A, Badger, J, Grimwood, J, Jabbari, K, Kuo, A, Maheswari, U, Martens, C, Maumus, F, Otillar, R, Rayko, E, Salamov, A, Vandepoele, K, Beszteri, B, Gruber, A, Heijde, M, Katinka, M, Mock, T, Valentin, K, Verret, F, Berges, J, Brownlee, C, Cadoret, Jean-paul, Chiovitti, A, Choi, C, Coesel, S, De Martino, A, Detter, J, Durkin, C, Falciatore, A, Fournet, J, Haruta, M, Huysman, M, Jenkins, B, Jiroutova, K, Jorgensen, R, Joubert, Y, Kaplan, A, Kroger, N, Kroth, P, La Roche, J, Lindquist, E, Lommer, M, Martin Jezequel, V, Lopez, P, Lucas, S, Mangogna, M, Mcginnis, K, Medlin, L, Montsant, A, Oudot Le Secq, M, Napoli, C, Obornik, M, Parker, M, Petit, J, Porcel, B, Poulsen, N, Robison, M, Rychlewski, L, Rynearson, T, Schmutz, J, Shapiro, H, Siaut, M, Stanley, M, Sussman, M, Taylor, A, Vardi, A, Von Dassow, P, Vyverman, W, Willis, A, Wyrwicz, L, Rokhsar, D, Weissenbach, J, Armbrust, E, Green, B, Van De Peer, Y, and Grigoriev Iv
- Abstract
Diatoms are photosynthetic secondary endosymbionts found throughout marine and freshwater environments, and are believed to be responsible for around one- fifth of the primary productivity on Earth(1,2). The genome sequence of the marine centric diatom Thalassiosira pseudonana was recently reported, revealing a wealth of information about diatom biology(3-5). Here we report the complete genome sequence of the pennate diatom Phaeodactylum tricornutum and compare it with that of T. pseudonana to clarify evolutionary origins, functional significance and ubiquity of these features throughout diatoms. In spite of the fact that the pennate and centric lineages have only been diverging for 90 million years, their genome structures are dramatically different and a substantial fraction of genes (similar to 40%) are not shared by these representatives of the two lineages. Analysis of molecular divergence compared with yeasts and metazoans reveals rapid rates of gene diversification in diatoms. Contributing factors include selective gene family expansions, differential losses and gains of genes and introns, and differential mobilization of transposable elements. Most significantly, we document the presence of hundreds of genes from bacteria. More than 300 of these gene transfers are found in both diatoms, attesting to their ancient origins, and many are likely to provide novel possibilities for metabolite management and for perception of environmental signals. These findings go a long way towards explaining the incredible diversity and success of the diatoms in contemporary oceans.
- Published
- 2008
- Full Text
- View/download PDF
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