Project description:The ability of the Antarctic microarthropod, Cryptopygus antarcticus (Collembola, Isotomidae), to survive low temperatures has been well studied at the physiological level. These investigations have indicated the importance of the moulting process in conferring this ability. This study investigated gene expression in groups of C. antarcticus that have distinct differences in their ability to survive low temperatures. A microarray containing 5,400 C. antarcticus expressed sequence tags was used to investigate gene expression differences between groups of animals with different supercooling points (SCP), and to low temperatures close to their SCP. By demonstrating the involvement of moulting genes in the differential survival of two groups of C. antarcticus with distinct SCPs, the results of this investigation add support to the role moulting plays in conferring cold tolerance in C. antarcticus.
Project description:Purpose: To compare transcriptomic changes in 3rd instar larval eye discs following sev-GAL4 driven down- or up- regulation of hsrω lncRNAs. Method: Eye disc total RNA profiles of wandering late third instar larvae of sev-GAL4>UAS-GFP, sev-GAL4>UAS-hsrωRNAi, sev-GAL4>EP3037 were generated by sequencing, in duplicate, using Illumina Hiseq2500 platform using 50bp pair-end reads, 6 samples per lane and each sample run across 2 lanes. This resulted in a sequencing depth of ~20 million reads. The resulting sequencing FastQ files were mapped to the Drosophila genome (dm6) using Tophat with Bowtie. The aligned SAM/BAM file for each was processed for guided transcript assembly using Cufflink 2.1.1 and gene counts were determined. Mapped reads were assembled using Cufflinks. Transcripts from all samples were subjected to Cuffmerge to get final transcriptome assembly across samples. In order to ascertain differential expression of gene transcripts between different samples, Cuffdiff 2.1.1 was used (Trapnell et al., 2012). Result: Using an optimized data analysis workflow, we mapped about 20 million sequence reads per sample to the Drosophila genome (dm6) and identified 15,905 transcripts with TopHat workflow in each genotypes studied. The sev-GAL4 driven expression of RNAi for hsromega gene transcripts in eye discs resulted in differential expression of many genes, with 409 genes being down-regulated and 100 up-regulated, when compared with those in sev-GAL4>UAS-GFP eye discs. Compared to control eye discs in case of up regulation of hsrω RNA, 66 gene were up-regulated while 635 were down-regulated. Some of these (11 genes) were validated using qRT-PCR. Conclusion: Analysis of RNA-seq data revealed that a large proportion of transcripts were indeed similarly affected by down- or up-regulation of hsrω RNA in normal as well as activated Ras expression background. A comparison of transcriptomes of sev-GAL4>hsrωRNAi and sev-GAL4>EP3037 eye discs revealed that in each case the number of genes down regulated was more than those up-regulated. Interestingly, while 319 genes were commonly down regulated and 15 were commonly up-regulated in the two genotypes, only 2 genes showed opposing trends between sev-GAL4>UAS-hsrωRNAi and sev-GAL4>EP3037 eye discs.
Project description:The Western Antarctic Peninsula (WAP) is among the areas of the planet showing some of the most significant increases in air and water temperature. It is projected that increasing temperature will modulate communities of coastal ecosystems at species ecological performance and molecular composition. The main way that the organisms can cope with large thermal variation is by having a reversible phenotypic plasticity, which provides the organisms with a compensatory physiological response when facing challenging conditions. However, since Antarctic organisms have evolved in a very cold and stable environment. The giant Antarctic isopod Glyptonotus antarcticus is one of the most abundant in Antarctic waters. This species has a larval development inside of maternal marsupium, where juveniles have a short period to acclimate to environmental conditions after birth. In this sense, we hypothesize that juveniles exposed to unusual temperature increases even for short periods, would not respond adequately showing a narrow phenotypic plasticity. We assessed if early juveniles of G. antarcticus have the molecular plasticity when exposed to increased temperature at 5¡C during 1, 6, 12, and 24 hours in comparison to control 0¡C. Sequenced HIseq2000 libraries were compared between control and each treatment to detect differentially expressed transcripts. The main molecular pathways affected by thermal stress were antioxidants, proteases, endopeptidases, and ubiquitination transcripts which were up-regulated, and mitochondrial respiratory chain, cuticle, cytoskeleton, and a molt transcript which were down-regulated. Considering HSP transcript, only 3 were up-regulated at least in two points of the stress kinetic, without classical HSP70 and HSP90 transcripts. This study shows that juveniles of G. antarcticus do not show molecular phenotypic plasticity to cope with acute short-term heat stress, even for one or few hours of exposure without an eco-physiological capacity to respond. This may have consequences at the ecological population level, showing a reduced individual ability to survive decreasing population recruitment.