30 research outputs found
Report on IOCCG Workshop Phytoplankton Composition from Space: towards a validation\ud strategy for satellite algorithms
The IOCCG-supported workshop âPhytoplankton Composition from Space: towards a validation strategy for satellite algorithmsâ was organized as a follow-up to the Phytoplankton Functional Types from Space splinter session, held at the International Ocean Colour Science Meeting (Germany, 2013). The specific goals of the workshop were to:
1. Provide a summary of the status of activities from relevant IOCCG working groups, the 2nd PFT intercomparison working group, PFT validation data sets and other research developments.
2. Provide a PFT validation strategy that considers the different applications of PFT products: and seeks community consensus on datasets and analysis protocols.
3. Discuss possibilities for sustaining ongoing PFT algorithm validation and intercomparison activities.
The workshop included 15 talks, breakout sessions and plenary discussions. Talks covered community algorithm intercomparison activity updates, review of established and novel methods for PFT validation, validation activities for specific applications and space-agency requirements for PFT products and validation. These were followed by general discussions on (a) major recommendations for global intercomparison initiative in respect to validation, intercomparison and userâs guide; (b) developing a community consensus on which data sets for validation are optimal and which measurement and analysis protocols should be followed to support sustained validation of PFT products considering different applications; (c) the status of different validation data bases and measurement protocols for different PFT applications, and (d) engagement of the various user communities for PFT algorithms in developing PFT product specifications.
From these discussions, two breakout groups provided in depth discussion and recommendations on (1) validation of current algorithms and (2) work plan to prepare for validation of future missions. Breakout group 1 provided an action list for progressing the current international community validation and intercomparison activity. Breakout group 2 provided the following recommendations towards developing a future validation strategy for satellite PFT products:
1. Establish a number of validation sites that maintain measurements of a key set of variables.
2. This set of variables should include:
âą Phytoplankton pigments from HPLC, phycobilins from spectrofluorometry
âą Phytoplankton cell counts and ID, volume / carbon estimation and imaging (e.g. from flow cytometry, FlowCam, FlowCytobot type technologies)
âą Inherent optical properties (e.g. absorption, backscattering, VSF)
âą Hyperspectral radiometry (both above and in-water)
âą Particle size distribution
âą Size-fractionated measurements of pigments and absorption
âą Genetic / -omics data
3. Undertake an intercomparison of methods / instruments over several years at a few sites to understand our capabilities to fully characterize the phytoplankton community.
4. Organise workshops to address the following topics:
âą Techniques for particle analysis, characterization and classification
âą Engagement with modellers and understanding end-user requirements
âą Data storage and management, standards for data contributors, data challenges
In conclusion, the workshop was assessed to have fulfilled its goals. A follow-on meeting will be organized during the International Ocean Colour Science Meeting 2015 in San Francisco. Specific follow-on actions are listed at the end of the report
Identification of CRISPR and riboswitch related RNAs among novel noncoding RNAs of the euryarchaeon Pyrococcus abyssi
<p>Abstract</p> <p>Background</p> <p>Noncoding RNA (ncRNA) has been recognized as an important regulator of gene expression networks in Bacteria and Eucaryota. Little is known about ncRNA in thermococcal archaea except for the eukaryotic-like C/D and H/ACA modification guide RNAs.</p> <p>Results</p> <p>Using a combination of <it>in silico </it>and experimental approaches, we identified and characterized novel <it>P</it>. <it>abyssi </it>ncRNAs transcribed from 12 intergenic regions, ten of which are conserved throughout the Thermococcales. Several of them accumulate in the late-exponential phase of growth. Analysis of the genomic context and sequence conservation amongst related thermococcal species revealed two novel <it>P</it>. <it>abyssi </it>ncRNA families. The CRISPR family is comprised of crRNAs expressed from two of the four <it>P</it>. <it>abyssi </it>CRISPR cassettes. The 5'UTR derived family includes four conserved ncRNAs, two of which have features similar to known bacterial riboswitches. Several of the novel ncRNAs have sequence similarities to orphan OrfB transposase elements. Based on RNA secondary structure predictions and experimental results, we show that three of the twelve ncRNAs include Kink-turn RNA motifs, arguing for a biological role of these ncRNAs in the cell. Furthermore, our results show that several of the ncRNAs are subjected to processing events by enzymes that remain to be identified and characterized.</p> <p>Conclusions</p> <p>This work proposes a revised annotation of CRISPR loci in <it>P</it>. <it>abyssi </it>and expands our knowledge of ncRNAs in the Thermococcales, thus providing a starting point for studies needed to elucidate their biological function.</p
Genome-wide investigation of mRNA lifetime determinants in Escherichia coli cells cultured at different growth rates
Lâutilisation de mesures indirectes et directes du comportement dans lâĂ©valuation des interventions ciblant les enfants agressifs
LâefficacitĂ© des interventions auxquelles sont exposĂ©s les enfants agressifs doit ĂȘtre Ă©valuĂ©e avec rigueur. Pour ce faire, les chercheurs et praticiens doivent disposer de mesures fiables, valides, exemptes de biais et qui soient suffisamment sensibles pour permettre de dĂ©tecter tout changement dans le comportement des enfants. Le premier objectif de cet article consiste Ă mettre en Ă©vidence les limites associĂ©es Ă lâutilisation de mesures indirectes pour Ă©valuer le comportement des enfants exposĂ©s Ă une intervention. Le second objectif vise Ă illustrer les enjeux associĂ©s Ă lâutilisation de mesures directes basĂ©es sur lâobservation du comportement. Une analyse des diffĂ©rentes possibilitĂ©s qui sâoffrent aux chercheurs et aux praticiens, notamment en ce qui a trait au choix des comportements ciblĂ©s par lâobservation et au contexte oĂč se dĂ©roule lâobservation, est proposĂ©e.Behavioral outcomes of intervention targeting young aggressive children have to be carefully assessed. Researchers and practioners need reliable, valid, and bias-free instruments that are also sensitive enough to detect any change in childrenâs behavior. The first goal of this article is to highlight limitations imposed by indirect measures of behavioral assessment with children exposed to an intervention. The second goal is to illustrate issues related to direct behavioral assessment using observation procedure. The different options for researchers and practioners regarding the choice of behavioral targets and observation settings are discussed.A eficĂĄcia das intervençÔes Ă s quais sĂŁo expostas as crianças agressivas deve ser avaliada com rigor. Para tal, os investigadores e os prĂĄticos devem dispor de mediçÔes fiĂĄveis, vĂĄlidas, isentas de enviesamentos e que sejam suficientemente sensĂveis para permitir detectar toda a mudança no comportamento das crianças. o primeiro objectivo deste artigo consiste em evidenciar os limites associados Ă utilização de mediçÔes indirectas para avaliar o comportamento das crianças expostas a uma intervenção. o segundo objectivo visa ilustrar os desafios associados Ă utilização de mediçÔes directas baseadas sobre a observação do comportamento. Ă© proposta uma anĂĄlise das diferentes possibilidades que se apresentam aos investigadores e aos prĂĄticos, nomeadamente no que se refere Ă escolha de comportamentos-alvo para a observação e ao contexto no qual se desenvolve a observação
EuGene: an eucaryotic gene finder that combines several sources of evidence
In this paper, we describe the basis of EuGne, a gene nder for eucaryotic organisms applied to Arabidopsis thaliana. The specicity of EuGne, compared to existing gene nding software, is that EuGne combines the output of several information sources, including output of other software, in a weighted directed acyclic graph (DAG) designed in such a way that a shortest path in this graph represents the most likely gene structure of the underlying ADN sequence. The usual simple Bellman linear time shortest path algorithm for DAG has been replaced by a shortest path with constraints algorithm. The constraints express minimum length of introns or intergenic regions. The specicity of the constraints leads to an algorithm which is still linear both in time and space. EuGne eectiveness has been assessed on Araset, a recent dataset of Arabidopsis thaliana sequences used to evaluate several existing gene nding software. It appears that, despite its simplicity, EuGne gives results..
EUGENE'HOM: a generic similarity-based gene finder using multiple homologous sequences
EUGE`NEâHOM is a gene prediction software for eukaryotic organisms based on comparative analysis. EUGE` NEâHOM is able to take into account multiple homologous sequences from more or less closely related organisms. It integrates the results of TBLASTX analysis, splice site and start codon prediction and a robust coding/non-coding probabilistic model which allows EUGE`NEâHOM to handle sequences from a variety of organisms. The current target of EUGE`NEâHOM is plant sequences. The EUGE`NEâHOM web site is available at http://genopole. toulouse.inra.fr/bioinfo/eugene/EuGeneHom/cgi-bin/EuGeneHom.pl
Diversity of CRISPR systems in the euryarchaeal Pyrococcales
International audiencePyrococcales are members of the order Thermococcales, a group of hyperthermophilic euryarchaea that are frequently found in deep sea hydrothermal vents. Infectious genetic elements, such as plasmids and viruses, remain a threat even in this remote environment and these microorganisms have developed several ways to fight their genetic invaders. Among these are the recently discovered CRISPR systems. In this review, we have combined and condensed available information on genetic elements infecting the Thermococcales and on the multiple CRISPR systems found in the Pyrococcales to fight them. Their organization and mode of action will be presented with emphasis on the Type III-B system that is the only CRISPR system known to target RNA molecules in a process reminiscent of RNA interference. The intriguing case of Pyrococcus abyssi, which is among the rare strains to present a CRISPR system devoid of the universal cas1 and cas2 genes, is also discussed