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ABSTRACT:
PROVIDER: PRJNA1050651 | ENA |
REPOSITORIES: ENA
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Project description:Prochlorococcus is found throughout the euphotic zone in the oligotrophic open ocean. Deep mixing and sinking in aggregates or while attached to particles can, however, transport cells below this sunlit zone, depriving them of light for extended periods of time and influencing their circulation via ocean currents. Viability of these cells over extended periods of darkness could shape the ecology and evolution of the Prochlorococcus collective. We have shown that when co-cultured with a heterotrophic microbe and subjected to repeated periods of extended darkness, Prochlorococcus cells develop a heritable dark-tolerant phenotype – through an apparent epigenetic mechanism – such that they survive longer periods of darkness. Here we examine this adaptation at the level of physiology and metabolism in co-cultures of dark-tolerant and parent strains of Prochlorococcus, each grown with the heterotroph Alteromonas under diel light:dark conditions. The relative abundance of Alteromonas is higher in dark-tolerant than parental co-cultures, while dark tolerant Prochlorococcus cells are also larger, contain less chlorophyll, and are less synchronized to the light:dark cycle. Meta-transcriptome analysis of the cultures further suggests that dark-tolerant co-cultures undergo a coupled shift in which Prochlorococcus uses more organic carbon and less photosynthesis, and Alteromonas uses more organic acids and fewer sugars. Collectively, the data suggest that dark adaptation involves a loosening of the coupling between Prochlorococcus metabolism and the light:dark cycle and a strengthening of the coupling between the carbon metabolism of Prochlorococcus and Alteromonas.
2024-04-23 | GSE264347 | GEO
Project description:Prochlorococcus genomes harbor a new type of mobile genetic elements named tycheposons. To study the effects on environmental stress on the gene expression and induction of tycheposons, we subjugated cultures of Prochlorococcus strain MIT0604 containing 7 such elements to treatments with mitomycin C and UV stress.
2021-04-04 | GSE171435 | GEO
Project description:We examine how the transcriptome of Prochlorococcus strain NATL2A changes in the presence of a naturally co-occurring heterotroph, Alteromonas macleodii MIT1002. Significant changes in the Prochlorococcus transcriptome were evident within six hours of co-culture, with groups of transcripts changing in different temporal waves. Many transcriptional changes persisted throughout the 48-hour experiment, indicating that the presence of the heterotroph affected a stable shift in Prochlorococcus physiology. These initial transcriptome changes largely correspond to reduced stress conditions within Prochlorococcus, as inferred from decreases in relative abundance for transcripts encoding DNA repair enzymes and many members of the âhigh-light inducibleâ family of stress response proteins. Notable changes were also seen in transcripts encoding components of the photosynthetic apparatus (particularly an increase in PSI subunits and chlorophyll synthesis enzymes), ribosomal proteins and biosynthetic enzymes. Changes in secretion-related proteins and transporters also highlight the potential for metabolic exchange between the two strains. At each of 7 timepoints, samples from 3 biological replicate co-cultures are compared to 3 biological replicate axenic Prochlorococcus cultures that serve as a control.
2016-06-10 | E-GEOD-73511 | biostudies-arrayexpress
Project description:Prochlorococcus contributes significantly to ocean primary productivity. The link between primary productivity and iron in specific ocean regions is well established and iron limitation of Prochlorococcus cell division rates in these regions has been shown. However, the extent of ecotypic variation in iron metabolism among Prochlorococcus and the molecular basis for differences is not understood. Here, we examine the growth and transcriptional response of Prochlorococcus strains, MED4 and MIT9313, to changing iron concentrations. During steady state, MIT9313 sustains growth at an order-of-magnitude lower iron concentration than MED4. To explore this difference, we measured the whole-genome transcriptional response of each strain to abrupt iron starvation and rescue. Only four of the 1159 orthologs of MED4 and MIT9313 were differentially expressed in response to iron in both strains. However, in each strain, the expression of over a hundred additional genes changed, many of which are in labile genomic regions, suggesting a role for lateral gene transfer in establishing diversity of iron metabolism among Prochlorococcus. Furthermore, we found that MED4 lacks three genes near the iron-deficiency-induced gene (idiA) that are present and induced by iron stress in MIT9313. These genes are interesting targets for studying the adaptation of natural Prochlorococcus assemblages to local iron conditions as they show more diversity than other genomic regions in environmental metagenomic databases.
2011-01-11 | GSE26533 | GEO
Project description:Prochlorococcus is a cyanobacterium of abundance in open ocean environments and little is known of its iron requirements or iron metabolism. We used microarrays to measure the whole-genome expression response of Prochlorococcus MED4 and MIT9313 to iron stress and recovery from iron stress.
2011-01-11 | E-GEOD-26533 | biostudies-arrayexpress
Project description:We examine how the transcriptome of Prochlorococcus strain NATL2A changes in the presence of a naturally co-occurring heterotroph, Alteromonas macleodii MIT1002. Significant changes in the Prochlorococcus transcriptome were evident within six hours of co-culture, with groups of transcripts changing in different temporal waves. Many transcriptional changes persisted throughout the 48-hour experiment, indicating that the presence of the heterotroph affected a stable shift in Prochlorococcus physiology. These initial transcriptome changes largely correspond to reduced stress conditions within Prochlorococcus, as inferred from decreases in relative abundance for transcripts encoding DNA repair enzymes and many members of the ‘high-light inducible’ family of stress response proteins. Notable changes were also seen in transcripts encoding components of the photosynthetic apparatus (particularly an increase in PSI subunits and chlorophyll synthesis enzymes), ribosomal proteins and biosynthetic enzymes. Changes in secretion-related proteins and transporters also highlight the potential for metabolic exchange between the two strains.
2016-06-10 | GSE73511 | GEO
Project description:Prochlorococcus is a genus of abundant and ecologically important marine cyanobacteria. Here, we present the comprehensive comparison of the structure and composition of the transcriptomes of two closely related Prochlorococcus strains, which, despite their similarities, have adapted their gene pool to specific environmental constraints. We used large-scale strand-specific cDNA sequencing, microarray RNA profiling and computational analyses to characterize the transcriptomes of Prochlorococcus sp. MED4 and Prochlorococcus sp. MIT9313, representatives of the two major ecotypes adapted to high and low light conditions, respectively. We present genome-wide maps of transcriptional start sites (TSS) for both organisms. Our data suggest antisense transcription for three quarters of all genes. A direct comparison revealed very little conservation in the use of TSS and the nature of non-coding transcripts between both strains. We conclude that the major transcriptional output from these highly streamlined genomes consists of antisense RNA and that a hitherto unrecognized high degree of variability exists in the transcriptional architecture of these rapidly evolving prokaryotes. Furthermore, we detected extremely short 5M-bM-^@M-^Y untranslated regions with a median length of only 27 nt and 29 nt for MED4 and MIT9313, respectively, and noticed the absence of the Shine-Dalgarno motif, which is suggestive of alternative mechanisms for the initiation of translation. For 8 % of all protein-coding genes, the median length to the initiator codon is 10 nt or shorter, suggesting that leaderless translation and ribosomal protein S1-dependent translation constitute the primary avenues for protein synthesis in Prochlorococcus. Prochlorococcus cells were either grown under standard growth conditions or various stress conditions (darkness, high light, iron or nitrogen depletion, cold or heat stress). Stress conditions were subsequently pooled and hybridized on one microarray.
2013-12-07 | E-GEOD-53065 | biostudies-arrayexpress
Project description:Cyanobacteria Prochlorococcus marinus subsp. pastoris str. CCMP1986 (MED4) and Prochlorococcus marinus str. MIT 9313 (MIT9313) are oceanic oxygenic phototrophs, where MED4 is abundant in surface waters (~0-50 meters) and MIT9313 is abundant at depths of ~100 meters. To explore nitrogen-regulated changes in gene expression in these Prochlorococcus ecotypes, log phase cultures of MED4 and MIT9313 were transferred to either nitrogen-replete (800 uM ammonium) or medium lacking supplemental nitrogen. Samples were taken over a time series in order to characterize changes in physiology and gene expression during increasing nitrogen starvation. The two ecotypes' molecular responses to different nitrogen sources were also assessed by comparing gene expression of log phase cultures growing in ammonium vs. urea and cyanate (MED4), and vs. urea and nitrite (MIT9313).
2007-10-11 | E-TABM-91 | biostudies-arrayexpress
Project description:Prochlorococcus is a genus of abundant and ecologically important marine cyanobacteria. Here, we present the comprehensive comparison of the structure and composition of the transcriptomes of two closely related Prochlorococcus strains, which, despite their similarities, have adapted their gene pool to specific environmental constraints. We used large-scale strand-specific cDNA sequencing, microarray RNA profiling and computational analyses to characterize the transcriptomes of Prochlorococcus sp. MED4 and Prochlorococcus sp. MIT9313, representatives of the two major ecotypes adapted to high and low light conditions, respectively. We present genome-wide maps of transcriptional start sites (TSS) for both organisms. Our data suggest antisense transcription for three quarters of all genes. A direct comparison revealed very little conservation in the use of TSS and the nature of non-coding transcripts between both strains. We conclude that the major transcriptional output from these highly streamlined genomes consists of antisense RNA and that a hitherto unrecognized high degree of variability exists in the transcriptional architecture of these rapidly evolving prokaryotes. Furthermore, we detected extremely short 5’ untranslated regions with a median length of only 27 nt and 29 nt for MED4 and MIT9313, respectively, and noticed the absence of the Shine-Dalgarno motif, which is suggestive of alternative mechanisms for the initiation of translation. For 8 % of all protein-coding genes, the median length to the initiator codon is 10 nt or shorter, suggesting that leaderless translation and ribosomal protein S1-dependent translation constitute the primary avenues for protein synthesis in Prochlorococcus.
2013-12-07 | GSE53065 | GEO
Project description:Prochlorococcus is an obligate marine microorganism which are dominant autotroph in tropical and subtropical central oceans. However, what is the low salinity boundary and how Prochlorococcus would response to low salinity exposure is still unknown. In this study, we first tested the growing salinity range of two Prochlorococcus strains, NATL1A and MED4, and then compared the global transcriptome of their low salinity acclimated cells and cells growing in normal seawater salinity. We found that MED4 could be acclimated in the lowest salinity of 25% and NATL1A could be acclimated in the lowest salinity of 28%. Measurement of the effective quantum yield of PSII photochemistry (Fv/Fm) indicated that both strains were stressed when growing in salinity lower than 34%. The transcriptomic response of NATL1A and MED4 were approximately different, with much more genes having changed transcript abundance in NATL1A than in MED4. To cope with low salinity, NATL1A downregulated the transcript of most genes involved in translation, ribosomal structure and biogenesis, while MED4 upregulated those genes. Moreover, low salinity acclimated NATL1A cells suppressed ATP-producing genes and induced the expression of photosynthesis related genes, while low salinity acclimated MED4 upregulated ATP-producing genes and downregulated photosynthesis related genes. These results indicate that the response to low salinity stress of different Prochlorococcus strains could be distinct. The study provided the first glimpse into the growing salinity range of Prochlorococcus cells and their global gene expression changes due to low salinity stress.
2022-02-02 | GSE195946 | GEO