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The inducible CO 2 concentrating mechanism (CCM) of microalgae is essential for their acclimation to highly variable aquatic inorganic carbon levels. The key transcriptional regulator, CIA5, affects expression of thousands of genes in Chlamydomonas reinhardtii , but the molecular characteristics of this important protein are poorly understood. This study identifies a functional activation domain in CIA5 and demonstrates the functionality of a mini-CIA5 including only the zinc-binding domain and the identified activation domain. A highly conserved 130aa region from CIA5 exhibits auto-activation in yeast and appears responsible for the markedly slow migration of CIA5 when analyzed by SDS-PAGE. This 130aa region or either half of this region also effectively replaced the activation domain of a modified designer Transcription Activator-like Element (dTALE) in targeted activation of an endogenous Chlamydomonas gene. Additionally, a mini-CIA5 combining the conserved zinc-binding domain with the 130aa putative activation domain complemented the growth phenotype of the cia5 mutant and triggered CO 2 -regulated gene expression patterns similar to wild-type cells or cia5 complemented with the full-length CIA5 . Although the mini-CIA5 complementation did not fully restore wild-type growth rates or full gene induction/repression amplitudes, especially in very low CO 2 , this newly identified activation domain combined with the previously described zinc-binding domain are demonstrated to be the key essential components of CIA5 that permit rapid CIA5-mediated responses to changes in CO 2 concentrations.

Posttranslational modification of proteins by small ubiquitin-like modifier (SUMO) is required for survival of virtually all eukaryotic organisms. Attachment of SUMO to target proteins is catalyzed by SUMO E2 conjugase. All haploid or diploid eukaryotes studied to date possess a single indispensable SUMO conjugase. We report here the unanticipated isolation of a Chlamydomonas reinhardtii (mutant5 [mut5]). in which the previously identified SUMO conjugase gene C. reinhardtii ubiquitin-conjugating enzyme9 (CrUBC9) is deleted. This surprising mutant is viable and unexpectedly, displays a pattern of protein SUMOylation at 25°C that is essentially identical to wild-type cells. However, unlike wild-type cells, mut5 fails to SUMOylate a large set of proteins in response to multiple stress conditions, a failure that results in a markedly reduced tolerance or complete lack of tolerance to these stresses. Restoration of expected stress-induced protein SUMOylation patterns as well as normal stress tolerance phenotypes in mut5 cells complemented with a CrUBC9 gene shows that CrUBC9 is an authentic SUMO conjugase and, more importantly, that SUMOylation is essential for cell survival under stress conditions. The presence of bona fide SUMOylated proteins in the mut5 mutant at 25°C can only be explained by the presence of at least one additional SUMO conjugase in C. reinhardtii, a conjugase tentatively identified as CrUBC3. Together, these results suggest that, unlike all other nonpolyploid eukaryotes, there are at least two distinct and functional SUMO E2 conjugases in C. reinhardtii, with a clear division of labor between the two sets: One (CrUBC9) is involved in essential stress-induced SUMOylations, and one (CrUBC3) is involved in housekeeping SUMOylations.

Multiple synonymous substitution mutations in the Wheat streak mosaic virus P3 cistron did not affect translation in vitro but rendered the virus incapable of systemic infection. Multiple synonymous substitutions in the cylindrical inclusion cistron did not alter infectivity or in vitro translation. To assess replication and movement phenotypes, P3 mutations were placed in context with a GUS reporter gene. GUS activity measured in barley protoplasts 36 h post-transfection indicated that mutants with synonymous substitutions in P3 retained the ability to replicate at 22–80 % of wild-type levels. Almost no GUS activity was detected in protoplasts transfected with a P3 frame-shift mutant. Histochemical GUS assays conducted 3 days post-inoculation (p.i.) revealed genomes with multiple synonymous substitutions in P3, which were able to establish infection foci limited to small clusters of cells that increased in size only slightly by 5 days p.i. Infection foci produced by wild-type Wheat streak mosaic virus-expressing GUS were much larger at 3 days p.i. and had coalesced by 5 days p.i. No GUS activity was detected in plants inoculated with the frame-shift mutant bearing GUS. Three of four mutants, each with a single synonymous substitution in the 3′-proximal half of the P3 cistron, were wild-type with respect to systemic infectivity. A model RNA secondary structure obtained for the region was disrupted by the debilitating single mutation but not by the other three single mutations. Collectively, these results identify an internal RNA sequence element in the P3 cistron that affects both replication and movement of the viral genome.

†‡ SUMMARY A significantly improved viral 2A peptide system for dependable high-level expression of dicistronic genes in Chlamydomonas reinhardtii has been developed. Data are presented demonstrating that use of an especially proficient ‘extended FMDV 2A’ coding region allows production of two independent protein products from a dicistronic gene with almost complete efficiency. Importantly, results are also presented that demonstrate the utility of this 2A system for efficient high-level expression of foreign genes in C. reinhardtii, which has not previously been reliably achievable in this algal model system. To expand the versatility of the 2A expression system, a number of commonly used selectable marker proteins were assessed for their compatibility with the extended FMDV 2A peptide. Additional experiments demonstrate the feasibility and utility of 2A-containing dicistronic systems that rely on a strong conditional promoter for transcriptional control and a low-expression marker gene for selection. This strategy allows easy and efficient delivery of genes of interest whose expression levels require regulation either to mitigate potential toxicity or allow differential expression under controlled experimental conditions. Finally, as an additional practical demonstration of the utility of the extended FMDV 2A system, confocal fluorescence microscopy is used to demonstrate that native and foreign proteins of interest bearing post-translational remnants of the extended FMDV 2A peptide localize correctly to various cellular compartments, including a striking demonstration of the almost exclusive localization of the Rubisco small subunit protein to the pyrenoid of the C. reinhardtii chloroplast in cells maintained under ambient CO2 concentrations.

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system has become a powerful and precise tool for targeted gene modification (e.g., gene knockout and gene replacement) in numerous eukaryotic organisms. Initial attempts to apply this technology to a model, the single-cell alga, Chlamydomonas reinhardtii , failed to yield cells containing edited genes. To determine if the Cas9 and single guide RNA (sgRNA) genes were functional in C. reinhardtii , we tested the ability of a codon-optimized Cas9 gene along with one of four different sgRNAs to cause targeted gene disruption during a 24-h period immediately following transformation. All three exogenously supplied gene targets as well as the endogenous FKB12 (rapamycin sensitivity) gene of C. reinhardtii displayed distinct Cas9/sgRNA-mediated target site modifications as determined by DNA sequencing of cloned PCR amplicons of the target site region. Success in transient expression of Cas9 and sgRNA genes contrasted with the recovery of only a single rapamycin-resistant colony bearing an appropriately modified FKB12 target site in 16 independent transformation experiments involving >10 9 cells. Failure to recover transformants with intact or expressed Cas9 genes following transformation with the Cas9 gene alone (or even with a gene encoding a Cas9 lacking nuclease activity) provided strong suggestive evidence for Cas9 toxicity when Cas9 is produced constitutively in C. reinhardtii . The present results provide compelling evidence that Cas9 and sgRNA genes function properly in C. reinhardtii to cause targeted gene modifications and point to the need for a focus on development of methods to properly stem Cas9 production and/or activity following gene editing.

The availability of the complete DNA sequence of the Chlamydomonas reinhardtii genome and advanced computational biology tools has allowed elucidation and study of the small ubiquitin-like modifier (SUMO) system in this unicellular photosynthetic alga and model eukaryotic cell system. SUMO is a member of a ubiquitin-like protein superfamily that is covalently attached to target proteins as a post-translational modification to alter the localization, stability, and/or function of the target protein in response to changes in the cellular environment. Three SUMO homologs (CrSUMO96, CrSUMO97, and CrSUMO148) and three novel SUMO-related proteins (CrSUMO-like89A, CrSUMO-like89B, and CrSUMO-like90) were found by diverse gene predictions, hidden Markov models, and database search tools inferring from Homo sapiens, Saccharomyces cerevisiae, and Arabidopsis thaliana SUMOs. Among them, CrSUMO96, which can be recognized by the A. thaliana anti-SUMO1 antibody, was studied in detail. Free CrSUMO96 was purified by immunoprecipitation and identified by mass spectrometry analysis. A SUMO-conjugating enzyme (SCE) (E2, Ubc9) in C. reinhardtii was shown to be functional in an Escherichia coli-based in vivo chimeric SUMOylation system. Antibodies to CrSUMO96 recognized free and conjugated forms of CrSUMO96 in Western blot analysis of whole-cell extracts and nuclear localized SUMOylated proteins with in situ immunofluorescence. Western blot analysis showed a marked increase in SUMO conjugated proteins when the cells were subjected to environmental stresses, such as heat shock and osmotic stress. Related analyses revealed multiple potential ubiquitin genes along with two Rub1 genes and one Ufm1 gene in the C. reinhardtii genome.

European Community Recent years have seen considerable progress in epidemiological and molecular genetic research into environmental and genetic factors in schizophrenia, but methodological uncertainties remain with regard to validating environmental exposures, and the population risk conferred by individual molecular genetic variants is small. There are now also a limited number of studies that have investigated molecular genetic candidate gene-environment interactions (G x E), however, so far, thorough replication of findings is rare and G x E research still faces several conceptual and methodological challenges. in this article, we aim to review these recent developments and illustrate how integrated, large-scale investigations may overcome contemporary challenges in G x E research, drawing on the example of a large, international, multi-center study into the identification and translational application of G x E in schizophrenia. While such investigations are now well underway, new challenges emerge for G x E research from late-breaking evidence that genetic variation and environmental exposures are, to a significant degree, shared across a range of psychiatric disorders, with potential overlap in phenotype. Maastricht Univ, Med Ctr, Dept Psychiat & Neuropsychol, Sch Mental Hlth & Neurosci,South Limburg Mental H, NL-6200 MD Maastricht, Netherlands Kings Coll London, Inst Psychiat, Dept Psychosis Studies, London WC2R 2LS, England Mondriaan Mental Hlth Trust, Maastricht, Heerlen, Netherlands Univ Groningen, Univ Med Ctr Groningen, Rob Giel Clin Res, Univ Ctr Psychiat, Groningen, Netherlands Kings Coll London, Inst Psychiat, Dept Hlth Serv & Populat Res, London WC2R 2LS, England Kings Coll London, Inst Psychiat, Dept Psychol, London WC2R 2LS, England Cardiff Univ, MRC, Ctr Neuropsychiat Genet, Cardiff CF10 3AX, S Glam, Wales Cent Inst Mental Hlth, Dept Psychiat & Psychotherapy, Mannheim, Germany Dokuz Eylul Univ, Sch Med, Dept Psychiat, Konak, Turkey Istanbul Univ, Istanbul Fac Med, Dept Psychiat, Psychot Disorders Res Unit, Istanbul, Turkey Ankara Univ, Sch Med, Dept Psychiat, Cebeci Hosp, TR-06100 Ankara, Turkey Ankara Univ, Brain Res Ctr, TR-06100 Ankara, Turkey Yale Univ, Sch Med, Dept Psychiat, New Haven, CT USA Middle E Tech Univ, Dept Psychol, TR-06531 Ankara, Turkey Diskapi YB Res & Training Hosp, Ankara, Turkey Turkish Federat Schizophrenia Assoc, Ankara, Turkey Ataturk Training & Res Hosp, Psychiat Clin, Ankara, Turkey Manisa Mental Hlth Hosp, Manisa, Turkey Istanbul Univ, Expt Med Res Inst, Dept Adv Neurol Sci, Istanbul Fac Med, Istanbul, Turkey Univ Complutense, IiSGM CIBERSAM, Dept Child & Adolescent Psychiat, Hosp Gen Univ Gregorio Maranon,Sch Med, E-28040 Madrid, Spain Univ Barcelona, Dept Psychiat, Hosp Clin, IDIBAPS,Ctr Invest Biomed Red Salud Mental CIBERS, Barcelona, Spain Univ Valencia, Sch Med, Dept Psychiat, Ctr Invest Biomed Red Salud Mental CIBERSAM, Valencia, Spain Univ Oviedo, Sch Med, Dept Med,Psychiat Area, Ctr Invest Biomed Red Salud Mental CIBERSAM, Oviedo, Spain Univ Santiago de Compostela, Dept Mental Hlth & Drug Addit Assistance, Hlth Serv Galicia,Psychiat Genet Grp IDIS, Hosp Clin,Ctr Invest Biomedica Red Salud Mental C, Santiago de Compostela 15706, Spain Hosp Virgen de la Luz, Serv Psiquiat, Dept Psychiat, Cuenca, Spain Hosp Univ Infanta Leonor Hosp Virgen Torre, Villa de Vallecas Mental Hlth Ctr, Villa de Vallecas Mental Hlth Dept, Madrid, Spain Hosp Univ Infanta Leonor Hosp Virgen Torre, Puente de Vallecas Mental Hlth Dept, Ctr Salud Mental Puente Vallecas, Madrid, Spain Hosp Clin Univ, Fdn Publ Galega Med Xenomica, Santiago de Compostela, Spain Univ Complutense, Sch Med, Hosp Gen Univ Gregorio Maranon, Dept Psychiat, E-28040 Madrid, Spain Hosp Psiquiatr Conxo, Santiago de Compostela, Spain Univ Amsterdam, Acad Med Ctr, Early Psychosis Sect, Dept Psychiat, NL-1105 AZ Amsterdam, Netherlands Vrije Univ Amsterdam, Dept Clin Psychol, Amsterdam, Netherlands EMGO Inst Hlth & Care Res, Amsterdam, Netherlands Parnassia Psychiat Inst, Dept Psychosis Res, the Hague, Netherlands Rivierduinen Psychiat Inst, Leiden, Netherlands Grp Hosp Mondor, AP HP, Creteil, France Hop Henri Mondor, INSERM, U955, Equipe 15, F-94010 Creteil, France Univ Paris Est, Fac Med, Creteil, France Fdn Fondamental, Creteil, France CMP B CHU, F-63003 Clermont Ferrand 1, France Univ Auvergne, EA 7280, Clermont Ferrand, France EPS Maison Blanche, Paris, France UPC KU Leuven, Dept Neurosci, UPC, Kortenberg, Belgium UPC, Dept Neurosci, Res Grp Psychiat, Leuven, Belgium Katholieke Univ Leuven, Univ Hosp Gasthuisberg, Dept Human Genet, Leuven, Belgium Assoc Sci Res Multiple Births, Ghent, Belgium Univ Ghent, Dept Neurol, Ghent Univ Hosp, B-9000 Ghent, Belgium Univ Athens, Sch Med, Eginit Hosp, Athens 11528, Greece Med Univ Vienna, Dept Psychiat & Psychotherapy, Vienna, Austria Psychiat Univ Clin Basel, Ctr Gender Res & Early Detect, Basel, Switzerland Psychiat Univ Clin Basel, Diagnost & Crisis Intervent Ctr, Basel, Switzerland Univ Cologne, Dept Psychiat & Psychotherapy, D-50931 Cologne, Germany Univ Hong Kong, Li Ka Shing Fac Med, Ctr Genom Sci, State Key Lab Brain & Cognit Sci, Hong Kong, Hong Kong, Peoples R China Univ Hong Kong, Li Ka Shing Fac Med, Dept Psychiat, Hong Kong, Hong Kong, Peoples R China Univ Hong Kong, Queen Mary Hosp, Li Ka Shing Fac Med, State Key Lab Brain & Cognit Sci, Hong Kong, Hong Kong, Peoples R China Univ Hong Kong, Queen Mary Hosp, Li Ka Shing Fac Med, Dept Psychiat, Hong Kong, Hong Kong, Peoples R China Univ Basque Country, Univ Deusto, Interuniv Chair Law & Human Genome Prov Govt Bisk, Bilbao, Bizkaia, Spain Univ Zaragoza, Zaragoza, Spain Univ Cambridge, Dept Psychiat, Cambridge, England UCL, Div Psychiat, London, England Royal Coll Surgeons Ireland, Beaumont Hosp, Educ & Res Ctr, Dept Psychiat, Dublin 9, Ireland Univ Munich, Dept Psychiat, Div Mol & Clin Neurobiol, Munich, Germany Univ Bologna, Alma Mater Studiorium, Psychiat Unit, Dept Med & Surg Sci, Bologna, Italy Univ Bologna, Alma Mater Studiorium, Genet Unit, Dept Med & Surg Sci, Bologna, Italy Local Hlth Trust, Dept Mental Hlth & Pathol Addict, Bologna, Italy Univ Palermo, Sect Psychiat, Dept Expt Biomed & Clin Neurosci, Palermo, Italy P Giaccone Gen Hosp, Unit Psychiat, Palermo, Italy Univ Melbourne, Ctr Youth Mental Hlth, Parkville, Vic 3052, Australia Univ Melbourne, Melbourne Neuropsychiat Ctr, Carlton, Vic, Australia Univ São Paulo, Fac Med, Dept Med Prevent, BR-01246903 São Paulo, Brazil Univ São Paulo, Nucleo Pesquina Saude Mental Populac, São Paulo, Brazil Univ São Paulo, Fac Med Ribeirao Preto, Dept Neurociencias & Ciencias Comportamento, BR-14049 Ribeirao Preto, Brazil Univ Verona, Sect Psychiat, Dept Publ Hlth & Community Med, I-37100 Verona, Italy Copenhagen Univ Hosp, Res Unit, Mental Hlth Ctr Copenhagen, Copenhagen, Denmark Univ Paris 05, Fac Med, Serv Hosp Univ, Hop St Anne, Paris, France Univ Autonoma Barcelona, Dept Psicol Clin & Salut, E-08193 Barcelona, Spain St Pere Claver Fundacio Sanitaria, Dept Salut Mental, Barcelona, Spain Univ N Carolina, Dept Psychol, Greensboro, NC 27412 USA CIBERSAM, Spanish Mental Hlth Res Network, Barcelona, Spain Universidade Federal de São Paulo, Dept Psychiat, PRISMA Early Intervent Program, São Paulo, Brazil Univ Belgrade, Sch Med, Beograd, Serbia Universidade Federal de São Paulo, Dept Psychiat, PRISMA Early Intervent Program, São Paulo, Brazil European Community: HEALTH-F2-2009-241909 Web of Science