5 research outputs found
A transcriptome resource for Antarctic krill (Euphausia superba Dana) exposed to short-term stress
Euphausia superba is a keystone species in Antarctic food webs. However, the continued decrease in stock density raises concerns over the resilience and adaptive potential of krill to withstand the current rate of environmental change. We undertook a transcriptome-scale approach (454 pyrosequencing) as a baseline for future studies addressing the physiological response of krill to short-term food shortage and natural UV-B stress. The final assembly resulted in a total of 26,415 contigs, 39.8% of which were putatively annotated. Exploratory analyses indicate an overall reduction in protein synthesis under food shortage while UV stress resulted in the activation of photo-protective mechanisms.Peer reviewe
Simple and rapid RNA extraction from freeze-dried tissue of brown algae and seagrasses
An inexpensive and rapid RNA extraction protocol for brown algae and seagrasses is presented, based on homogenization in a simple CTAB buffer and selective precipitation of RNA with lithium chloride. The protocol avoids the use of toxic chaotropic agents and phenol; high concentrations of dithiothreitol are used to inhibit RNase activity and to prevent oxidative cross-linking of nucleic acids by phenolics. A relatively high throughput of about 100 samples in 24 h can be achieved for, for example, Northern analysis. Yields of 50–200 µg g−1 fresh weight are comparable with those obtained for higher plants using commercially available kits. Tests of the extraction procedure demonstrate that high quality, intact RNA can be obtained from a variety of lyophilized brown algal tissues, even after prolonged storage at room temperature. Lyophilization is therefore suggested as an alternative to freezing tissue at −70°C to −80°C. The RNA obtained was used directly in several downstream applications to detect Fucus plastid-encoded transcripts by RNA-labelling, RT-PCR and Northern analysis
An expressed sequence tag analysis of the intertidal brown seaweeds Fucus serratus (L.) and F. vesiculosus (L.) (Heterokontophyta, Phaeophyceae) in response to abiotic stressors
In order to aid gene discovery and uncover genes responding to abiotic stressors in stress-tolerant brown algae of the genus Fucus, expressed sequence tags (ESTs) were studied in two species, Fucus serratus and Fucus vesiculosus. Clustering of over 12,000 ESTs from three libraries for heat shock/recovery and desiccation/rehydration
resulted in identification of 2,503, 1,290, and 2,409 unigenes from heat-shocked F. serratus, desiccated F. serratus, and desiccated F. vesiculosus, respectively.
Low overall annotation rates (18–31%) were strongly associated with the presence of long 3′ untranslated regions in Fucus transcripts, as shown by analyses of predicted protein-coding sequence in annotated and nonannotated tentative consensus sequences. Posttranslational modification genes were overrepresented in the heat shock/recovery library, including many chaperones, the most abundant of which were a family of small heat shock protein transcripts, Hsp90 and Hsp70 members. Transcripts of LI818-like light-harvesting genes implicated in photoprotection were
also expressed during heat shock in high light. The expression of several heat-shock-responsive genes was confirmed by quantitative reverse transcription polymerase
chain reaction. However, candidate genes were notably absent from both desiccation/rehydration libraries, while
the responses of the two species to desiccation were divergent, perhaps reflecting the species-specific physiological
differences in stress tolerance previously established. Desiccation-tolerant F. vesiculosus overexpressed at least 17 ribosomal protein genes and two ubiquitinribosomal protein fusion genes, suggesting that ribosome function and/or biogenesis are important during cycles of
rapid desiccation and rehydration in the intertidal zone and possibly indicate parallels with other poikilohydric organisms
such as desiccation-tolerant bryophytes