Temperature influences nearly all biochemical, physiological and life history activities of fish, but the molecular mechanisms underlying the temperature acclimation remains largely unknown. Previous studies have identified many temperature-regulated genes in adult tissues; however, the transcriptional responses of fish larvae to temperature stress are not well understood. In this study, we characterized the transcriptional responses in larval zebrafish exposed to cold or heat stress using microarray analysis. In comparison with genes expressed in the control at 28°C, a total of 2680 genes were found to be affected in 96 hpf larvae exposed to cold (16°C) or heat (34°C) for 2 and 48h and most of these genes were expressed in a temperature-specific and temporally regulated manner. Bioinformatic analysis identified multiple temperature-regulated biological processes and pathways. Biological processes overrepresented among the earliest genes induced by temperature stress include regulation of transcription, nucleosome assembly, chromatin organization and protein folding. However, processes such as RNA processing, cellular metal ion homeostasis and protein transport and were enriched in genes up-regulated under cold exposure for 48 h. Pathways such as mTOR signalling, p53 signalling and circadian rhythm were enriched among cold-induced genes, while adipocytokine signalling, protein export and arginine and praline metabolism were enriched among heat-induced genes. Although most of these biological processes and pathways were specifically regulated by cold or heat, common responses to both cold and heat stresses were also found. Thus, these findings provide new interesting clues for elucidation of mechanisms underlying the temperature acclimation in fish.
The p8 protein is a transcription factor with a basic helix-loop-helix motif and a nuclear localization signal. In the present study, a common sea urchin (Paracentrotus lividus) homolog of p8 cDNA was cloned, sequenced and characterized. The full-length p8 cDNA consists of 896 bp and encodes 71 amino acids with a molecular mass of 8.238 kD. Homology alignments found that several phosphorylation sites and the most negative (Asp and Glu)/positive (Arg) propensities charged residues were well conserved between P. lividus and other species. Analysis by RT-PCR showed that there was no obvious difference in the patterns of expression during embryogenesis from unfertilization egg up to the pluteus stage, but p8 mRNA expression levels varied among tested adult tissues suggesting that p8 has a key function in embryogenesis but non-vital function under physiological conditions. Evolution relationships between P. lividus p8 and other species p8 homologs revealed in the phylogenetic tree were in agreement with the concept of traditional taxonomy.
In wireless sensor networks (WSNs), group key distribution is the core of secure communications since sensor nodes usually form groups and cooperate with each other in sensing data collection and in-network processing. In this paper, we present a scalable authenticated scheme for group key distribution based on a combinatorial exclusion basis system (EBS) for efficiency and one-way hash chains for authentication. The proposed scheme guarantees a lightweight authenticated group key updating procedure and is efficient in terms of storage, communication and computation overheads.
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