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  • Proceedings of the National Academy of Sciences  (4)
  • 1
    Online Resource
    Online Resource
    Triassic origin and early radiation of multicellular volvocine algae
    Proceedings of the National Academy of Sciences ; 2009
    In:  Proceedings of the National Academy of Sciences Vol. 106, No. 9 ( 2009-03-03), p. 3254-3258
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 106, No. 9 ( 2009-03-03), p. 3254-3258
    Abstract: Evolutionary transitions in individuality (ETIs) underlie the watershed events in the history of life on Earth, including the origins of cells, eukaryotes, plants, animals, and fungi. Each of these events constitutes an increase in the level of complexity, as groups of individuals become individuals in their own right. Among the best-studied ETIs is the origin of multicellularity in the green alga Volvox , a model system for the evolution of multicellularity and cellular differentiation. Since its divergence from unicellular ancestors, Volvox has evolved into a highly integrated multicellular organism with cellular specialization, a complex developmental program, and a high degree of coordination among cells. Remarkably, all of these changes were previously thought to have occurred in the last 50–75 million years. Here we estimate divergence times using a multigene data set with multiple fossil calibrations and use these estimates to infer the times of developmental changes relevant to the evolution of multicellularity. Our results show that Volvox diverged from unicellular ancestors at least 200 million years ago. Two key innovations resulting from an early cycle of cooperation, conflict and conflict mediation led to a rapid integration and radiation of multicellular forms in this group. This is the only ETI for which a detailed timeline has been established, but multilevel selection theory predicts that similar changes must have occurred during other ETIs.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.0811205106
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2009
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Diel cycling and long-term persistence of viruses in the ocean’s euphotic zone
    Proceedings of the National Academy of Sciences ; 2017
    In:  Proceedings of the National Academy of Sciences Vol. 114, No. 43 ( 2017-10-24), p. 11446-11451
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 114, No. 43 ( 2017-10-24), p. 11446-11451
    Abstract: Viruses are fundamental components of marine microbial communities that significantly influence oceanic productivity, biogeochemistry, and ecosystem processes. Despite their importance, the temporal activities and dynamics of viral assemblages in natural settings remain largely unexplored. Here we report the transcriptional activities and variability of dominant dsDNA viruses in the open ocean’s euphotic zone over daily and seasonal timescales. While dsDNA viruses exhibited some fluctuation in abundance in both cellular and viral size fractions, the viral assemblage was remarkably stable, with the most abundant viral types persisting over many days. More extended time series indicated that long-term persistence ( 〉 1 y) was the rule for most dsDNA viruses observed, suggesting that both core viral genomes as well as viral community structure were conserved over interannual periods. Viral gene transcription in host cell assemblages revealed diel cycling among many different viral types. Most notably, an afternoon peak in cyanophage transcriptional activity coincided with a peak in Prochlorococcus DNA replication, indicating coordinated diurnal coupling of virus and host reproduction. In aggregate, our analyses suggested a tightly synchronized diel coupling of viral and cellular replication cycles in both photoautotrophic and heterotrophic bacterial hosts. A surprising consequence of these findings is that diel cycles in the ocean’s photic zone appear to be universal organizing principles that shape ecosystem dynamics, ecological interactions, and biogeochemical cycling of both cellular and acellular community components.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1714821114
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2017
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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  • 3
    Online Resource
    Online Resource
    Endogenous DNA viruses take center stage in eukaryotic genome evolution
    Proceedings of the National Academy of Sciences ; 2023
    In:  Proceedings of the National Academy of Sciences Vol. 120, No. 21 ( 2023-05-23)
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 120, No. 21 ( 2023-05-23)
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.2305212120
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2023
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Microbial community transcriptional networks are conserved in three domains at ocean basin scales
    Proceedings of the National Academy of Sciences ; 2015
    In:  Proceedings of the National Academy of Sciences Vol. 112, No. 17 ( 2015-04-28), p. 5443-5448
    Details
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 17 ( 2015-04-28), p. 5443-5448
    Abstract: Planktonic microbial communities in the ocean are typically dominated by several cosmopolitan clades of Bacteria , Archaea , and Eukarya characterized by their ribosomal RNA gene phylogenies and genomic features. Although the environments these communities inhabit range from coastal to open ocean waters, how the biological dynamics vary between such disparate habitats is not well known. To gain insight into the differential activities of microbial populations inhabiting different oceanic provinces we compared the daily metatranscriptome profiles of related microbial populations inhabiting surface waters of both a coastal California upwelling region (CC) as well as the oligotrophic North Pacific Subtropical Gyre (NPSG). Transcriptional networks revealed that the dominant photoautotrophic microbes in each environment ( Ostreococcus in CC, Prochlorococcus in NPSG) were central determinants of overall community transcriptome dynamics. Furthermore, heterotrophic bacterial clades common to both ecosystems (SAR11, SAR116, SAR86, SAR406, and Roseobacter ) displayed conserved, genome-wide inter- and intrataxon transcriptional patterns and diel cycles. Populations of SAR11 and SAR86 clades in particular exhibited tightly coordinated transcriptional patterns in both coastal and pelagic ecosystems, suggesting that specific biological interactions between these groups are widespread in nature. Our results identify common diurnally oscillating behaviors among diverse planktonic microbial species regardless of habitat, suggesting that highly conserved temporally phased biotic interactions are ubiquitous among planktonic microbial communities worldwide.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
    URL: Article
    DOI: 10.1073/pnas.1502883112
    RVK:
    TA 1000
    RVK:
    WA 15000
    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
    Location Call Number Limitation Availability
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    Online Resource
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