Volvox carteri
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PROVIDER: PRJNA13110 | ENA |
REPOSITORIES: ENA
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Project description:MicroRNAs in a multicellular green alga Volvox carteri
| PRJNA227453 | ENA
Project description:The green alga Volvox carteri is a model organism for the development of multicellularity. It has a spherical shape with a complete division of labor between around 2000 somatic cells and 16 reproductive cells. When comparing Volvox with its unicellular relative Chlamydomonas rheinhardtii, one striking observation is the similarity in the protein coding genes [1]. Additionally, Baulcombe and colleagues showed that Chlamydomonas contains functional RNAi and miRNA machineries [2]. We deep sequenced small RNAs of the female Volvox strain HK10 in different life stages (asexual reproduction to sexual reproduction), each time dividing the samples into somatic cells and reproductive cells. This allowed for the observation not only of differences in individual life stages, but also for monitoring sRNA content in the two cell types. We show that Volvox expresses miRNAs and that they are 2â??-O-methylated at the 3â?? end. The expression profiles of several miRNAs were validated by Northern blotting showing a differential expression both between cell types and between life stages. Intriguingly, most miRNAs do not seem to be conserved between Volvox and Chlamydomonas, raising the interesting question if this changed miRNome leads to differently targeted mRNAs thus resulting in cell differentiation. Since only little is known about the transcriptome of Volvox, we performed RNASeq in order to analyze potential miRNA targets. In conclusion, most miRNA in Volvox are not conserved in Chlamydomonas although the two species are evolutionary close together. This suggests that dramatic changes in the miRNA expression might be one of the driving forces for the development of multicellularity. 1. Prochnik, S.E., et al., Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri. Science, 2010. 329(5988): p. 223-6. 2. Molnar, A., et al., miRNAs control gene expression in the single-cell alga Chlamydomonas reinhardtii. Nature, 2007. 447(7148): p. 1126-9. Examination of small RNAs of Volvox carteri during different stages of its life cycle
2016-07-01 | E-GEOD-58704 | BioStudies
Project description:Epigenetic silencing of foreign genes introduced into plants poses an unsolved problem for transgenic technology. Here we have used the simple multicellular green alga VOLVOX: carteri as a model to analyse the relation of DNA methylation to transgenic silencing. VOLVOX: DNA contains on average 1.1% 5-methylcytosine and 0.3% N6-methyladenine, as revealed by electrospray mass spectrometry and phosphoimaging of chromatographically separated (32)P-labelled nucleotides. In two nuclear transformants of V.carteri, produced in 1993 by biolistic bombardment with a foreign arylsulphatase gene (C-ars), the transgene is still expressed in one (Hill 181), but not in the other (Hill 183), after an estimated 500-1000 generations. Each transformant clone contains multiple intact copies of C-ars, most of them integrated into the genome as tandem repeats. When the bisulphite genomic sequencing protocol was applied to examine two select regions of transgenic C-ars, we found that the inactivated copies (Hill 183) exhibited a high-level methylation (40%) of CpG dinucleotides, whereas the active copies (Hill 181) displayed low-level (7%) CpG methylation. These are average values from 40 PCR clones sequenced from each DNA strand in the two portions of C-ars. The observed correlation of CpG methylation and transgene inactivation in a green alga will be discussed in the light of transcriptional silencing.
2001-01-01 | S-EPMC29749 | BioStudies
Project description:The multicellular green alga Volvox carteri and its morphologically diverse close relatives (the volvocine algae) are well suited for the investigation of the evolution of multicellularity and development. We sequenced the 138-mega-base pair genome of V. carteri and compared its approximately 14,500 predicted proteins to those of its unicellular relative Chlamydomonas reinhardtii. Despite fundamental differences in organismal complexity and life history, the two species have similar protein-coding potentials and few species-specific protein-coding gene predictions. Volvox is enriched in volvocine-algal-specific proteins, including those associated with an expanded and highly compartmentalized extracellular matrix. Our analysis shows that increases in organismal complexity can be associated with modifications of lineage-specific proteins rather than large-scale invention of protein-coding capacity.
2010-01-01 | S-EPMC2993248 | BioStudies
Project description:<h4>Background</h4>Alternative splicing is an essential mechanism for increasing transcriptome and proteome diversity in eukaryotes. Particularly in multicellular eukaryotes, this mechanism is involved in the regulation of developmental and physiological processes like growth, differentiation and signal transduction.<h4>Results</h4>Here we report the genome-wide analysis of alternative splicing in the multicellular green alga Volvox carteri. The bioinformatic analysis of 132,038 expressed sequence tags (ESTs) identified 580 alternative splicing events in a total of 426 genes. The predominant type of alternative splicing in Volvox is intron retention (46.5%) followed by alternative 5' (17.9%) and 3' (21.9%) splice sites and exon skipping (9.5%). Our analysis shows that in Volvox at least ~2.9% of the intron-containing genes are subject to alternative splicing. Considering the total number of sequenced ESTs, the Volvox genome seems to provide more favorable conditions (e.g., regarding length and GC content of introns) for the occurrence of alternative splicing than the genome of its close unicellular relative Chlamydomonas. Moreover, many randomly chosen alternatively spliced genes of Volvox do not show alternative splicing in Chlamydomonas. Since the Volvox genome contains about the same number of protein-coding genes as the Chlamydomonas genome (~14,500 protein-coding genes), we assumed that alternative splicing may play a key role in generation of genomic diversity, which is required to evolve from a simple one-cell ancestor to a multicellular organism with differentiated cell types (Mol Biol Evol 31:1402-1413, 2014). To confirm the alternative splicing events identified by bioinformatic analysis, several genes with different types of alternatively splicing have been selected followed by experimental verification of the predicted splice variants by RT-PCR.<h4>Conclusions</h4>The results show that our approach for prediction of alternative splicing events in Volvox was accurate and reliable. Moreover, quantitative real-time RT-PCR appears to be useful in Volvox for analyses of relationships between the appearance of specific alternative splicing variants and different kinds of physiological, metabolic and developmental processes as well as responses to environmental changes.
2014-01-01 | S-EPMC4378016 | BioStudies
Project description:Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.
2015-01-01 | S-EPMC4416025 | BioStudies
Project description:The green alga Volvox carteri is a model organism for the development of multicellularity. It has a spherical shape with a complete division of labor between around 2000 somatic cells and 16 reproductive cells. When comparing Volvox with its unicellular relative Chlamydomonas rheinhardtii, one striking observation is the similarity in the protein coding genes [1]. Additionally, Baulcombe and colleagues showed that Chlamydomonas contains functional RNAi and miRNA machineries [2]. We deep sequenced small RNAs associated with one Argonaute protein of the female Volvox strain Vol6 during its vegetative growth phase. Using these data, we established a miRNA identification pipeline that takes into account plant miRNA feature in general and also uses parameters employed in finding miRNAs in Chlamydomonas. Other small RNAs that are functionally incorporated into Ago are characterized. 1. Prochnik, S.E., et al., Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri. Science, 2010. 329(5988): p. 223-6. 2. Molnar, A., et al., miRNAs control gene expression in the single-cell alga Chlamydomonas reinhardtii. Nature, 2007. 447(7148): p. 1126-9. Examination of small RNAs bound to an Argonaute protein of Volvox carteri
2016-07-01 | E-GEOD-59469 | ArrayExpress
Project description:The green alga Volvox carteri is a model organism for the development of multicellularity. It has a spherical shape with a complete division of labor between around 2000 somatic cells and 16 reproductive cells. When comparing Volvox with its unicellular relative Chlamydomonas rheinhardtii, one striking observation is the similarity in the protein coding genes [1]. Additionally, Baulcombe and colleagues showed that Chlamydomonas contains functional RNAi and miRNA machineries [2]. We deep sequenced small RNAs of the female Volvox strain HK10 in different life stages (asexual reproduction to sexual reproduction), each time dividing the samples into somatic cells and reproductive cells. This allowed for the observation not only of differences in individual life stages, but also for monitoring sRNA content in the two cell types. We show that Volvox expresses miRNAs and that they are 2’-O-methylated at the 3’ end. The expression profiles of several miRNAs were validated by Northern blotting showing a differential expression both between cell types and between life stages. Intriguingly, most miRNAs do not seem to be conserved between Volvox and Chlamydomonas, raising the interesting question if this changed miRNome leads to differently targeted mRNAs thus resulting in cell differentiation. Since only little is known about the transcriptome of Volvox, we performed RNASeq in order to analyze potential miRNA targets. In conclusion, most miRNA in Volvox are not conserved in Chlamydomonas although the two species are evolutionary close together. This suggests that dramatic changes in the miRNA expression might be one of the driving forces for the development of multicellularity. 1. Prochnik, S.E., et al., Genomic analysis of organismal complexity in the multicellular green alga Volvox carteri. Science, 2010. 329(5988): p. 223-6. 2. Molnar, A., et al., miRNAs control gene expression in the single-cell alga Chlamydomonas reinhardtii. Nature, 2007. 447(7148): p. 1126-9. Examination of small RNAs of Volvox carteri during different stages of its life cycle
2016-07-01 | E-GEOD-58704 | ArrayExpress
Project description:The multicellular green alga Volvox carteri represents an attractive model system to study various aspects of multicellularity like cellular differentiation, morphogenesis, epithelial folding and ECM biogenesis. However, functional and molecular analyses of such processes require a wide array of molecular tools for genetic engineering. So far there are only a limited number of molecular tools available in Volvox.Here, we show that the promoter of the V. carteri nitrate reductase gene (nitA) is a powerful molecular switch for induction of transgene expression. Strong expression is triggered by simply changing the nitrogen source from ammonium to nitrate. We also show that the luciferase (g-luc) gene from the marine copepod Gaussia princeps, which previously was engineered to match the codon usage of the unicellular alga Chlamydomonas reinhardtii, is a suitable reporter gene in V. carteri. Emitted light of the chemiluminescent reaction can be easily detected and quantified with a luminometer. Long-term stability of inducible expression of the chimeric nitA/g-luc transgenes after stable nuclear transformation was demonstrated by transcription analysis and bioluminescence assays.Two novel molecular tools for genetic engineering of Volvox are now available: the nitrate-inducible nitA promoter of V. carteri and the codon-adapted luciferase reporter gene of G. princeps. These novel tools will be useful for future molecular research in V. carteri.
2015-01-01 | S-EPMC4339647 | BioStudies
Project description:With only two different cell types, the haploid green alga Volvox represents the simplest multicellular model system. To facilitate genetic investigations in this organism, the occurrence of homologous recombination events was investigated with the intent of developing methods for gene replacement and gene disruption. First, homologous recombination between two plasmids was demonstrated by using overlapping nonfunctional fragments of a recombinant arylsulfatase gene (tubulin promoter/arylsulfatase gene). After bombardment of Volvox reproductive cells with DNA-coated gold microprojectiles, transformants expressing arylsulfatase constitutively were recovered, indicating the presence of the machinery for homologous recombination in Volvox. Second, a well characterized loss-of-function mutation in the nuclear nitrate reductase gene (nitA) with a single G --> A nucleotide exchange in a 5'-splice site was chosen as a target for gene replacement. Gene replacement by homologous recombination was observed with a reasonably high frequency only if the replacement vector containing parts of the functional nitrate reductase gene contained only a few nucleotide exchanges. The ratio of homologous to random integration events ranged between 1:10 and 1:50, i.e., homologous recombination occurs frequently enough in Volvox to apply the powerful tool of gene disruption for functional studies of novel genes.
1997-01-01 | S-EPMC23845 | BioStudies