Environmental Barcoding Reveals Massive Dinoflagellate Diversity in Marine Environments

Rowena F. Stern is with University of British Columbia, Ales Horak is with University of British Columbia, Rose L. Andrew is with University of British Columbia, Mary-Alice Coffroth is with State University of New York at Buffalo, Robert A. Andersen is with the Bigelow Laboratory for Ocean Sciences, Frithjof C. Küpper is with the Scottish Marine Institute, Ian Jameson is with CSIRO Marine and Atmospheric Research, Mona Hoppenrath is with the German Center for Marine Biodiversity Research, Benoît Véron is with University of Caen Lower Normandy and the National Institute for Environmental Studies, Fumai Kasai is with the National Institute for Environmental Studies, Jerry Brand is with UT Austin, Erick R. James is with University of British Columbia, Patrick J. Keeling is with University of British Columbia.Background -- Dinoflagellates are an ecologically important group of protists with important functions as primary producers, coral symbionts and in toxic red tides. Although widely studied, the natural diversity of dinoflagellates is not well known. DNA barcoding has been utilized successfully for many protist groups. We used this approach to systematically sample known “species”, as a reference to measure the natural diversity in three marine environments. Methodology/Principal Findings -- In this study, we assembled a large cytochrome c oxidase 1 (COI) barcode database from 8 public algal culture collections plus 3 private collections worldwide resulting in 336 individual barcodes linked to specific cultures. We demonstrate that COI can identify to the species level in 15 dinoflagellate genera, generally in agreement with existing species names. Exceptions were found in species belonging to genera that were generally already known to be taxonomically challenging, such as Alexandrium or Symbiodinium. Using this barcode database as a baseline for cultured dinoflagellate diversity, we investigated the natural diversity in three diverse marine environments (Northeast Pacific, Northwest Atlantic, and Caribbean), including an evaluation of single-cell barcoding to identify uncultivated groups. From all three environments, the great majority of barcodes were not represented by any known cultured dinoflagellate, and we also observed an explosion in the diversity of genera that previously contained a modest number of known species, belonging to Kareniaceae. In total, 91.5% of non-identical environmental barcodes represent distinct species, but only 51 out of 603 unique environmental barcodes could be linked to cultured species using a conservative cut-off based on distances between cultured species. Conclusions/Significance -- COI barcoding was successful in identifying species from 70% of cultured genera. When applied to environmental samples, it revealed a massive amount of natural diversity in dinoflagellates. This highlights the extent to which we underestimate microbial diversity in the environment.This project was funded by Genome Canada and the Canadian Barcode of Life Network. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Biological Sciences, School o

EMDR Therapy Mechanisms Explained by the Theory of Neural Cognition

International audienceEye Movement Desensitization and Reprocessing (EMDR) is a therapy of choice for post-traumatic stress disorder (PTSD). The mechanism of EMDR therapy is still unknown but it is hypothesized to favor memory reconsolidation. A new learning occurs relieved from the emotional load. Based on the Theory of neural Cognition (TnC), we propose an explanation of this phenomenon that implicates hebbian synaptic plasticity, i.e., long-term potentiation (LTP) and long-term depression (LTD). The new learning is mediated by the bilateral alternating stimulations (BAS) that are essential to the EMDR therapy. These repeated BAS modify the neural traces of a traumatic memory through the incorporation of newly activated cortical columns. These activated columns form a sparse coding representation of the situation called the global state of activation (GSA). Some of these added cortical activities will eventually crystallize in a column’s activation that is able to join the current GSA, making a new GSA, i.e., a stable network of activity. This process (trauma recall and BAS) is repeated several times, and each time, the activity of new columns is being added to the current GSA, until a GSAn totally cleared of its emotional content is obtained. Each GSA is a stable network of activity which gets reinforced thanks to LTP. Each time, a lessened traumatic memory is experienced. These modifications end up with a shift from the amygdalae’s involvement in the traumatic memory towards a more cognitive representation of the traumatic event, exempt from the previously associated strong negative feeling

Genome Evolution in Outcrossing vs. Selfing vs. Asexual Species

International audienceA major current molecular evolution challenge is to link comparative genomic patterns to species' biology and ecology. Breeding systems are pivotal because they affect many population genetic processes and thus genome evolution. We review theoretical predictions and empirical evidence about molecular evolutionary processes under three distinct breeding systems-outcrossing, selfing, and asexuality. Breeding systems may have a profound impact on genome evolution, including molecular evolutionary rates, base composition, genomic conflict, and possibly genome size. We present and discuss the similarities and differences between the effects of selfing and clonality. In reverse, comparative and population genomic data and approaches help revisiting old questions on the long-term evolution of breeding systems