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Articoli di riviste sul tema "Chlamydomonas reinhardtii – Genetics":
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Roesler, Keith R., e William L. Ogren. "Chlamydomonas reinhardtii Phosphoribulokinase". Plant Physiology 93, n. 1 (1 maggio 1990): 188–93. http://dx.doi.org/10.1104/pp.93.1.188.
Stauber, Einar J., e Michael Hippler. "Chlamydomonas reinhardtii proteomics". Plant Physiology and Biochemistry 42, n. 12 (dicembre 2004): 989–1001. http://dx.doi.org/10.1016/j.plaphy.2004.09.008.
Lamb, Mary Rose, Susan K. Dutcher, Cathy K. Worley e Carol L. Dieckmann. "Eyespot-Assembly Mutants in Chlamydomonas reinhardtii". Genetics 153, n. 2 (1 ottobre 1999): 721–29. http://dx.doi.org/10.1093/genetics/153.2.721.
Abstract Chlamydomonas reinhardtii is a single-celled green alga that phototaxes toward light by means of a light-sensitive organelle, the eyespot. The eyespot is composed of photoreceptor and Ca++-channel signal transduction components in the plasma membrane of the cell and reflective carotenoid pigment layers in an underlying region of the large chloroplast. To identify components important for the positioning and assembly of a functional eyespot, a large collection of nonphototactic mutants was screened for those with aberrant pigment spots. Four loci were identified. eye2 and eye3 mutants have no pigmented eyespots. min1 mutants have smaller than wild-type eyespots. mlt1(ptx4) mutants have multiple eyespots. The MIN1, MLT1(PTX4), and EYE2 loci are closely linked to each other; EYE3 is unlinked to the other three loci. The eye2 and eye3 mutants are epistatic to min1 and mlt1 mutations; all double mutants are eyeless. min1 mlt1 double mutants have a synthetic phenotype; they are eyeless or have very small, misplaced eyespots. Ultrastructural studies revealed that the min1 mutants are defective in the physical connection between the plasma membrane and the chloroplast envelope membranes in the region of the pigment granules. Characterization of these four loci will provide a beginning for the understanding of eyespot assembly and localization in the cell.
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Kuchka, Michael R., e Jonathan W. Jarvik. "Short-Flagella Mutants of Chlamydomonas reinhardtii". Genetics 115, n. 4 (1 aprile 1987): 685–91. http://dx.doi.org/10.1093/genetics/115.4.685.
ABSTRACT Six short-flagella mutants were isolated by screening clones of mutagenized Chlamydomonas for slow swimmers. The six mutants identify three unlinked Mendelian genes, with three mutations in gene shf-1, two in shf-2 and one in shf-3. shf-1 and shf-2 have been mapped to chromosomes VI and I, respectively. Two of the shf-1 mutations have temperature-sensitive flagellar-assembly phenotypes, and one shf-2 mutant has a cold-sensitive phenotype. shf shf double mutants were constructed; depending on the alleles present they showed either flagellaless or short-flagella phenotypes. Phenotypic revertants of shf-1 and shf-2 mutants were isolated, and certain of them were found to carry extragenic suppressors, some dominant and some recessive. We suspect that the shf mutations affect components of a specific flagellar size-control system, the existence of which has been suggested by a variety of physiological experiments.
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Porter, Mary E., Julie A. Knott, Steven H. Myster e Samuel J. Farlow. "The Dynein Gene Family in Chlamydomonas reinhardtii". Genetics 144, n. 2 (1 ottobre 1996): 569–85. http://dx.doi.org/10.1093/genetics/144.2.569.
Abstract To correlate dynein heavy chain (Dhc) genes with flagellar mutations and gain insight into the function of specific dynein isoforms, we placed eight members of the Dhc gene family on the genetic map of Chlamydomonas. Using a PCR-based strategy, we cloned 11 Dhc genes from Chlamydomonas. Comparisons with other Dhc genes indicate that two clones correspond to genes encoding the alpha and beta heavy chains of the outer dynein arm. Alignment of the predicted amino acid sequences spanning the nucleotide binding site indicates that the remaining nine clones can be subdivided into three groups that are likely to include representatives of the inner-arm Dhc isoforms. Gene-specific probes reveal that each clone represents a single-copy gene that is expressed as a transcript of the appropriate size (>13 kb) sufficient to encode a high molecular weight Dhc polypeptide. The expression of all nine genes is upregulated in response to deflagellation, suggesting a role in axoneme assembly or motility. Restriction fragment length polymorphisms between divergent C. reinhardtii strains have been used to place each Dhr gene on the genetic map of Chlamydomonas. These studies lay the groundwork for correlating defects in different Dhc genes with specific flagellar mutations.
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Shimogawara, Kosuke, Shoko Fujiwara, Arthur Grossman e Hideaki Usuda. "High-Efficiency Transformation of Chlamydomonas reinhardtii by Electroporation". Genetics 148, n. 4 (1 aprile 1998): 1821–28. http://dx.doi.org/10.1093/genetics/148.4.1821.
Abstract We have established a high-efficiency method for transforming the unicellular, green alga Chlamydomonas reinhardtii by electroporation. Electroporation of strains CC3395 and CC425, cell wall-less mutants devoid of argininosuccinate lyase (encoded by ARG7), in the presence of the plasmid pJD67 (which contains ARG7) was used to optimize conditions for the introduction of exogenous DNA. The conditions that were varied included osmolarity, temperature, concentration of exogenous DNA, voltage and capacitance. Following optimization, the maximum transformation frequency obtained was 2 × 105 transformants per μg of DNA; this frequency is two orders of magnitude higher than obtained with the current standard method using glass beads to introduce exogenous DNA. The electroporation procedure described in this article is of general utility, and makes it feasible to isolate genes by direct complementation of Chlamydomonas reinhardtii mutants.
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Dutcher, S. K., R. E. Galloway, W. R. Barclay e G. Poortinga. "Tryptophan analog resistance mutations in Chlamydomonas reinhardtii." Genetics 131, n. 3 (1 luglio 1992): 593–607. http://dx.doi.org/10.1093/genetics/131.3.593.
Abstract Forty single gene mutations in Chlamydomonas reinhardtii were isolated based on resistance to the compound 5'-methyl anthranilic acid (5-MAA). In other organisms, 5-MAA is converted to 5'-methyltryptophan (5-MT) and 5-MT is a potent inhibitor of anthranilate synthase, which catalyzes the first committed step in tryptophan biosynthesis. The mutant strains fall into two phenotypic classes based on the rate of cell division in the absence of 5-MAA. Strains with class I mutations divide more slowly than wild-type cells. These 17 mutations map to seven loci, which are designated MAA1 to MAA7. Strains with class II mutations have generation times indistinguishable from wild-type cells, and 7 of these 23 mutations map to loci defined by class I mutations. The remainder of the class II mutations map to 9 other loci, which are designated MAA8-MAA16. The maa5-1 mutant strain excretes high levels of anthranilate and phenylalanine into the medium. In this strain, four enzymatic activities in the tryptophan biosynthetic pathway are increased at least twofold. These include the combined activities of anthranilate phosphoribosyl transferase, phosphoribosyl anthranilate isomerase, indoleglycerol phosphate synthetase and anthranilate synthase. The slow growth phenotypes of strains with class I mutations are not rescued by the addition of tryptophan, but the slow growth phenotype of the maa6-1 mutant strain is partially rescued by the addition of indole. The maa6-1 mutant strain excretes a fluorescent compound into the medium, and cell extracts have no combined anthranilate phosphoribosyl transferase, phosphoribosyl anthranilate isomerase and indoleglycerol phosphate synthetase activity. The MAA6 locus is likely to encode a tryptophan biosynthetic enzyme. None of the other class I mutations affected these enzyme activities. Based on the phenotypes of double mutant strains, epistatic relationships among the class I mutations have been determined.
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Grossman, Arthur R. "Chlamydomonas reinhardtii and photosynthesis: genetics to genomics". Current Opinion in Plant Biology 3, n. 2 (aprile 2000): 132–37. http://dx.doi.org/10.1016/s1369-5266(99)00053-9.
Ferris, P. J. "Characterization of a Chlamydomonas transposon, Gulliver, resembling those in higher plants." Genetics 122, n. 2 (1 giugno 1989): 363–77. http://dx.doi.org/10.1093/genetics/122.2.363.
Abstract While pursuing a chromosomal walk through the mt+ locus of linkage group VI of Chlamydomonas reinhardtii, I encountered a 12-kb sequence that was found to be present in approximately 12 copies in the nuclear genome. Comparison of various C. reinhardtii laboratory strains provided evidence that the sequence was mobile and therefore a transposon. One of two separate natural isolates interfertile with C. reinhardtii, C. smithii (CC-1373), contained the transposon, but at completely different locations in its nuclear genome than C. reinhardtii; and a second, CC-1952 (S1-C5), lacked the transposon altogether. Genetic analysis indicated that the transposon was found at dispersed sites throughout the genome, but had a conserved structure at each location. Sequence homology between the termini was limited to an imperfect 15-bp inverted repeat. An 8-bp target site duplication was created by insertion; transposon sequences were completely removed upon excision leaving behind both copies of the target site duplication, with minor base changes. The transposon contained an internal region of unique repetitive sequence responsible for restriction fragment length heterogeneity among the various copies of the transposon. In several cases it was possible to identify which of the dozen transposons in a given strain served as the donor when a transposition event occurred. The transposon often moved into a site genetically linked to the donor, and transposition appeared to be nonreplicative. Thus the mechanism of transposition and excision of the transposon, which I have named Gulliver, resembles that of certain higher plant transposons, like the Ac transposon of maize.
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Bennoun, P., M. Delosme e U. Kück. "Mitochondrial genetics of Chlamydomonas reinhardtii: resistance mutations marking the cytochrome b gene." Genetics 127, n. 2 (1 febbraio 1991): 335–43. http://dx.doi.org/10.1093/genetics/127.2.335.
Abstract We describe the genetic and molecular analysis of the first non-Mendelian mutants of Chlamydomonas reinhardtii resistant to myxothiazol, an inhibitor of the respiratory cytochrome bc1 complex. Using a set of seven oligonucleotide probes, restriction fragments containing the mitochondrial cytochrome b (cyt b) gene from C. reinhardtii were isolated from a mitochondrial DNA library. This gene is located adjacent to the gene for subunit 4 of the mitochondrial NADH-dehydrogenase (ND4), near one end of the 15.8-kb linear mitochondrial genome of C. reinhardtii. The algal cytochrome b apoprotein contains 381 amino-acid residues and exhibits a sequence similarity of about 59% with other plant cytochrome b proteins. The cyt b gene from four myxothiazol resistant mutants of C. reinhardtii was amplified for DNA sequence analysis. In comparison to the wild-type strain, all mutants contain an identical point mutation in the cyt b gene, leading to a change of a phenylalanine codon to a leucine codon at amino acid position 129 of the cytochrome b protein. Segregation analysis in tetrads from reciprocal crosses of mutants with wild type shows a strict uniparental inheritance of this mutation from the mating type minus parent (UP-). However, mitochondrial markers from both parents are recovered in vegetative diploids in variable proportions from one experiment to the next for a given cross. On the average, a strong bias is seen for markers inherited from the mating type minus parent.
Tesi sul tema "Chlamydomonas reinhardtii – Genetics":
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Goho, Shaun. "The accumulation of variance in fitness in clonal populations of Chlamydomonas reinhardtii in normal and stressful environments /". Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27328.
The work presented here investigates two basic properties of mutation rates in the unicellular chlorophyte Chlamydomonas reinhardtii. The first chapter is devoted to an investigation of the mutational heritability $ rm (V sb{M})$ of fitness in asexually propagated populations. This is the rate at which novel variation for fitness accumulates in a population. In two trials, values of $ rm V sb{M}$ = 4.5 and $4.7 times 10 sp{-3}$ of the environmental variance $ rm (V sb{E})$ were obtained. These values were at least an order of magnitude greater than estimates from other organisms of $ rm V sb{M}/V sb{E}$ for fitness or for quasineutral variation. The possibility that this was due to disruptive selection for types specialized for different parts of the culturing environment was investigated, and rejected. Other possible explanations, and future avenues for research, are discussed. The second chapter extends the investigation from normal culturing conditions into stressful ones. Specifically, it considers the hypothesis that C. reinhardtii might increase its mutation rate as a general response to environmental stress. Stressed lines were found to display reduced mean fitness and an increased variance of fitness after being returned to normal culturing conditions. This was interpreted as evidence for increased mutation rates in treated lines relative to controls. Possible mechanisms underlying this phenomenon are discussed, along with suggestions for further research.
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Chao, Vincent 1973. "Ecological and sexual divergence in experimental populations of Chlamydomonas". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=32982.
Laboratory studies on speciation have revealed that selection must be disruptively applied on traits related to the mating system in order to produce deviations from random mating in experimental populations. One problem with these experiments, however, has been the complexity of the model organism used, most frequently Drosophila species. Due to the multi genic nature of the mating systems of such organisms, it has been difficult to obtain the necessary gene combinations that result in complete sexual isolation. In the present study, I have used a simple sexual organism, the unicellular green algae Chlamydomonas reinhardtii, as a model for ecological and sexual differentiation. Disruptive selection was applied on the flagella, by selecting simultaneously for photo taxis and mating, behaviours for which these organelles are of fundamental importance. An asymmetric response to selection for photo taxis and zygote production was obtained in populations selected for conditions at opposite ends of the environmental spectrum used, differentiating these two populations in both movement capacity and mating efficiency. These results are discussed in relation to previous experiments on speciation and to the implications of future experimental studies on the same subject.
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Stevens, David Roy. "Nuclear transformation and gene expression in Chlamydomonas reinhardtii". Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362931.
Wong, Ka-ho, e 王家豪. "Transgenic chlamydomonas reinhardtii as an experimental system to study the regulation of carotenoid biosynthesis in green microalgae". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37728337.
Hessenberger, Daisy Sophia Innes. "Small RNA and genome interactions in Chlamydomonas reinhardtii recombinants". Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/274914.
When conspecific individuals are crossed, the ensuing hybridization creates a spectrum of phenotypes in the resulting offspring. Many of hybrid traits will be additive, similar to the parental phenotypes. In some cases however, transgressive phenotypes are formed, outside the range of that of the parental phenotypes. Transgressive phenotypes can either be restricted to the F1 generation or be heritable throughout the hybrid lineage. While the mechanism behind heritable transgressive phenotyped is yet to be determined, transgressive gene expression is thought to be the root cause of their formation. Epigenetics modifications, heritable variation separate to the DNA code, can alter gene expression, persist through generations, and vary between individuals and over time. This makes them ideal candidates to be involved in the formation of transgressive phenotypes. RNA silencing is an epigenetic mechanism of gene regulation relying on 20Q24nt single stranded small RNAs (sRNAs). Small RNAs, due to their ability to set up persistent epigenetic marks at a locus, have the potential to create heritable transgressive gene expression. For example, when genetic variation from one parental genome presents novel targets to the sRNAs of the other parental genome, new epigenetic marks such as DNA methylation or secondary sRNAs can be created at target sites. In order to understand the potential of small RNAs to influence hybrid phenotype, I designed crossing experiments with Chlamydomonas reinhardtii, choosing this unicellular alga due to the genetic tools available and the haploid nature of its vegetative cells. The specific aim of the experiment was to identify transgressively expressed sRNA populations. Crossing two geographically distinct strains of C. reinhardtii, and sequencing both the genomes and sRNAomes of parents and recombinants, I was able catalogue both genetic and epigenetic variation in the parental strains providing unique insight into the inheritance of small RNAs in this alga. In this thesis, I first compare the genomes of the parental strains, identifying polymorphisms and assessing genetic variation in RNA silencing pathway components. I then describe the sRNA profiles of the parental strains, identifying differentially expressed sRNA loci. I then describe my approach to identifying transgressively expressed sRNA loci in the hybrids. While many sRNA loci in the recombinants exhibit additive sRNA expression, I found multiple transgressively expressed sRNA loci. Using the available bioinformatics tools, I identified potential miRNAs and phased secondary sRNAs within the list of transgressively expressed loci. Target analysis of one of the transgressively expressed miRNAs linked it with the transgressive expression of certain phased loci, suggesting a potential for sRNAs to be able to set up heritable epigenetic marks in recombinant C. reinhardtii cells.
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Feldman, Jessica L. "Deconstructing cell architecture: Exploring centriole structure, function, and position in the green alga Chlamydomonas reinhardtii". Diss., Search in ProQuest Dissertations & Theses. UC Only, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3324579.
Zeyl, Clifford. "Sex, parasitic DNA and adaptation in experimental populations of Saccharomyces cerevisiae and Chlamydomonas reinhardtii". Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40475.
The widespread occurrence among eukaryotes of sex and of mobile DNA sequences requires an evolutionary explanation, since both appear to reduce individual fitness. Both phenomena have been hypothesized to provide fitness advantages to populations, but such explanations require rather than explain the initial establishment of mobile elements and genes for sex. Genes encoding sexuality may invade asexual populations as molecular parasites, whose success then allows mobile elements to spread as parasites of sexual genomes. The prediction that mobile elements can invade only sexual populations was tested using isogenic sexual and asexual populations of Saccharomyces cerevisiae and the retrotransposon Ty3. Active Ty3 elements more consistently invaded sexual than asexual populations. In subsequent experiments involving selection on media containing ethanol as a carbon source or $ beta$-glycerophosphate as a limiting phosphorus source, transposition by galactose-induced Ty3 elements produced none of the mutations involved in adaptation to these media, and conferred no adaptive advantage among competing populations. The mean copy numbers of two mobile elements were unchanged by long-term sexual or asexual propagation of Chlamydomonas reinhardtii populations, because transposition by these elements occurred very rarely or had no effect on fitness. Sexual and asexual S. cerevisiae populations did not differ in their adaptation to galactose media, but sexual populations maintained on glucose had higher growth rates on both media than did asexual populations maintained on glucose, implying that selection against deleterious mutations was more effective in sexual populations.
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Gaskill, Christa. "Towards an Action Spectrum for Photoentrainment of the Chlamydomonas ReinhardtII Circadian Clock". TopSCHOLAR®, 2008. http://digitalcommons.wku.edu/theses/43.
Castonguay, Andrew David. "Analysis of mutants impaired for respiratory growth in the model photosynthetic alga, Chlamydomonas reinhardtii". The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619140884575211.
Barbieri, Maria del Rosario. "The green alga Chlamydomonas reinhardtii: a new model system to unravel the biogenesis of respiratory complexes". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1271966493.
Capitoli di libri sul tema "Chlamydomonas reinhardtii – Genetics":
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Blaby, Ian K., e Crysten E. Blaby-Haas. "Genomics and Functional Genomics in Chlamydomonas reinhardtii". In Chlamydomonas: Molecular Genetics and Physiology, 1–26. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66365-4_1.
Hauser, C. R., B. L. Randolph-Anderson, T. M. Hohl, E. H. Harris, J. E. Boynton e N. W. Gillham. "Molecular Genetics of Chloroplast Ribosomes in Chlamydomonas Reinhardtii". In The Translational Apparatus, 545–54. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-2407-6_51.
Rochaix, J. D., M. Goldschmidt-Clermont, Y. Choquet, Y. Takahashi, M. Kuchka, J. Girard-Bascou e P. Bennoun. "Chloroplast Gene Expression and Reverse Genetics in Chlamydomonas Reinhardtii". In Regulation of Chloroplast Biogenesis, 9–16. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3366-5_2.
Moellering, Eric R., Rachel Miller e Christoph Benning. "Molecular Genetics of Lipid Metabolism in the Model Green Alga Chlamydomonas reinhardtii". In Lipids in Photosynthesis, 139–55. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-2863-1_7.
Li, Xiaobo, e Martin C. Jonikas. "High-Throughput Genetics Strategies for Identifying New Components of Lipid Metabolism in the Green Alga Chlamydomonas reinhardtii". In Subcellular Biochemistry, 223–47. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-25979-6_10.
Neupert, Juliane, Ning Shao, Yinghong Lu e Ralph Bock. "Genetic Transformation of the Model Green Alga Chlamydomonas reinhardtii". In Methods in Molecular Biology, 35–47. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-558-9_4.
Dutcher, Susan K. "Genetic Properties of Linkage Group XIX in Chlamydomonas Reinhardtii". In Extrachromosomal Elements in Lower Eukaryotes, 303–25. Boston, MA: Springer US, 1986. http://dx.doi.org/10.1007/978-1-4684-5251-8_24.
Fernández, E., e J. Cárdenas. "Genetic Control of Nitrate Reductase in the Green Alga Chlamydomonas reinhardtii". In Inorganic Nitrogen Metabolism, 108–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-71890-8_16.
Rochaix, J. D. "Chlamydomonas reinhardtii". In Brenner's Encyclopedia of Genetics, 521–24. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-12-374984-0.00230-8.
Atti di convegni sul tema "Chlamydomonas reinhardtii – Genetics":
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"Role of GATA-family transcription factors in the regulation of chlorophyll biosynthesis in green unicellular algae Chlamydomonas reinhardtii". In Plant Genetics, Genomics, Bioinformatics, and Biotechnology. Novosibirsk ICG SB RAS 2021, 2021. http://dx.doi.org/10.18699/plantgen2021-033.
Puzansky, R. K., e M. F. Shishova. "Metabolomic and molecular genetic aspects of trophic adaptation of mutants Chlamydomonas reinhardtii". In IX Congress of society physiologists of plants of Russia "Plant physiology is the basis for creating plants of the future". Kazan University Press, 2019. http://dx.doi.org/10.26907/978-5-00130-204-9-2019-366.
Chekunova, E. M., A. B. Matiiv e T. S. Ushkina. "INVESTIGATIONS OF THE GENETIC MECHANISMS OF PLANT CELL ADAPTATION TO THE LIGHT ON THE MODEL OF CHLOROPHYLL-LESS MUTANTS OF UNICELLULAR GREEN ALGAE CHLAMYDOMONAS REINHARDTII". In The All-Russian Scientific Conference with International Participation and Schools of Young Scientists "Mechanisms of resistance
of plants and microorganisms to unfavorable environmental". SIPPB SB RAS, 2018. http://dx.doi.org/10.31255/978-5-94797-319-8-1003-1007.
Rapporti di organizzazioni sul tema "Chlamydomonas reinhardtii – Genetics":
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Stern, David, e Gadi Schuster. Manipulation of Gene Expression in the Chloroplast. United States Department of Agriculture, settembre 2000. http://dx.doi.org/10.32747/2000.7575289.bard.
The steady-state level of a given mRNA is determined by its rates of transcription and degradation. The stabilities of chloroplast mRNAs vary during plant development, in part regulating gene expression. Furthermore, the fitness of the organelle depends on its ability to destroy non-functional transcripts. In addition, there is a resurgent interest by the biotechnology community in chloroplast transformation due to the public concerns over pollen transmission of introduced traits or foreign proteins. Therefore, studies into basic gene expression mechanisms in the chloroplast will open the door to take advantage of these opportunities. This project was aimed at gaining mechanistic insights into mRNA processing and degradation in the chloroplast and to engineer transcripts of varying stability in Chlamydomonas reinhardtii cells. This research uncovered new and important information on chloroplast mRNA stability, processing, degradation and translation. In particular, the processing of the 3' untranslated regions of chloroplast mRNAs was shown to be important determinants in translation. The endonucleolytic site in the 3' untranslated region was characterized by site directed mutagensis. RNA polyadenylation has been characterized in the chloroplast of Chlamydomonas reinhardtii and chloroplast transformants carrying polyadenylated sequences were constructed and analyzed. Data obtained to date suggest that chloroplasts have gene regulatory mechanisms which are uniquely adapted to their post-endosymbiotic environment, including those that regulate RNA stability. An exciting point has been reached, because molecular genetic studies have defined critical RNA-protein interactions that participate in these processes. However, much remains to be learned about these multiple pathways, how they interact with each other, and how many nuclear genes are consecrated to overseeing them. Chlamydomonas is an ideal model system to extend our understanding of these areas, given its ease of manipulation and the existing knowledge base, some of which we have generated.
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Stern, David B., e Gadi Schuster. Manipulation of Gene Expression in the Chloroplast: Control of mRNA Stability and Transcription Termination. United States Department of Agriculture, dicembre 1993. http://dx.doi.org/10.32747/1993.7568750.bard.
Chloroplasts are the site of photosynthesis and of other essential biosynthetic activities in plant cells. Chloroplasts are semi-autonomous organelles, since they contain their own genomes and protein biosynthetic machinery, but depend on the coordinate expression of nuclear genes to assemble macromolecular complexes. The bioeingineering of plants requires manipulation of chloroplast gene expression, and thus a knowledge of the molecular mechanisms that modulate mRNA and protein production. In this proposal the heterotrophic green alga Chlamydomonas reinhardtii has been used as a model system to understand the control and interrelationships between transcription termination, mRNA 3' end processing and mRNA stability in chloroplasts. Chlamydomonas is a unique and ideal system in which to address these issues, because the chloroplast can be easily manipulated by genetic transformation techniques. This research uncovered new and important information on chloroplast mRNA 3' end formation and mRNA stability. In particular, the 3' untranslated regions of chloroplast mRNAs were shown not to be efficient transcription terminators. The endonucleolytic site in the 3' untranslated region was characterized by site directed mutagensis and the role of several 3' untranslated regions in modulating RNA stability and translation has been studied. This information will allow us to experimentally manipulate the expression of chloroplast genes in vivo by post-transcriptional mechanisms, and should be widely applicable to other higher plant systems.
