Project description:Purpose: Corals are major sources of dimethylsulphoniopropionate (DMSP), a compound that plays a central role in the global sulphur cycle. While DMSP biosynthesis pathways have been investigated in plants and algae, the molecular basis for its production by corals is unknown. Given its potential role as an osmolyte, the effect of salinity stress on levels of DMSP was investigated in both adults and juveniles (lacking photosynthetic symbionts) of the coral Acropora millepora. This study used transcriptomic data to analyse the effects of salinity over the coral A. millepora and to identify coral genes likely to be involved in DMSP biosynthesis. Methods: Adults coral transcriptomic libraries were constructed from samples exposed during 1 and 24 hours of salinity treatment (25 PSU) and control (35 PSU) conditions (n=5 per condition). Juveniles coral transcriptomic libraries were constructed from samples exposed to 24 and 48 hours of salinity treatment (28 PSU) and control (35 PSU) conditions (n=6 per condition). All libraries were sequenced by 100 bp paired-end in a HiSeq 2000. Reads were mapped onto the Acropora millepora genome using TopHat2 to produce a count data gene expression matrix for subsequent gene expression analysis using DESeq2 package. Results: In adult coral samples, 5.5 - 10.2 million RNAseq reads were obtained for each treatment sampling time while 3.4 - 8.8 million reads were obtained for each juvenile coral sample. The count matrix of the 26,622 A. millepora gene predictions were generated using htseq-count workflow. BlastP analysis of the A. millepora gene predictions led to the identification of coral members of gene families implicated in DMSP biosynthesis in other organisms, while RNA-seq data was used to identify the differentially expressed ones in response to hyposaline stress and on this basis were considered to be candidates for roles in DMSP biosynthesis in corals. Conclusions: Hyposaline stress increased DMSP production in both adults and aposymbiotic juvenile corals, and transcriptomic analyses highlighted the potential involvement of specific candidate genes in the production of DMSP via an alga-like pathway. The biochemistry of DMSP production is not well established for any eukaryotic system and, as the first animals in which it has been demonstrated, this is particularly true in the case of corals. Our RNA-seq results enabled the identification of candidates for roles in DMSP biosynthesis in corals but, given its critical roles in diverse biological processes, a thorough investigation of the molecular mechanisms leading to its production by corals is required.
Project description:This experiment assessed the natural gene expression variation present between colonies of the Indo-Pacific reef-building coral Acropora millepora, and additionally explored whether gene expression differed between two different intron haplotypes according to intron 4-500 in a carbonic anhydrase homolog. This study found no correspondence between host genotype and transcriptional state, but found significant intercolony variation, detecting 488 representing unique genes or 17% of the total genes analyzed. Such transcriptomic variation could be the basis upon which natural selection can act. Underlying variation could potentially allow reef corals to respond to different environments. Whether this source of variation and the genetic responses of corals and its symbionts will allow coral reefs to cope to the rapid pace of global change remains unknown.
Project description:We used the Illumina RNAseq approach to study the effects of acute exposure to elevated CO2 on gene expression in primary polyps of Acropora millepora Examination of transcriptome in Acropora millepora primary polyps at 380, 750 and 1000 ppm CO2 after 3 days exposure
Project description:We used the Illumina RNAseq approach to study the effects of acute exposure to elevated CO2 on gene expression in primary polyps of Acropora millepora
