Combination analysis of the physiology and transcriptome provides insights into the mechanism of silver nanoparticles phytotoxicity.

Silver nanoparticles (AgNPs) have adverse impacts on plants when released into environments, but their toxic mechanism is still a matter of debate. Here we present a combined analysis of physiology and transcriptome of Arabidopsis thaliana leaves exposure to 30 mg L-1 AgNPs and Ag+ for six days to explore the toxicity mechanism of AgNPs on Arabidopsis. Both transcriptomic and physiological results showed that AgNPs induced reactive oxygen species (ROS) accumulation and damaged photosynthesis. The toxicity of AgNPs is not merely attributable to Ag+ release and much higher photosynthetic toxicity and ROS accumulation were observed in 30 mg L-1 AgNPs than that in 0.12 mg L-1 Ag+. About 60% genes were similarly up- or down-regulated at the same concentration of AgNPs and Ag+ and these genes were enriched in photosynthesis and response to the stimulus. However, 302 genes, including those involved in glucosinolates synthesis, were specifically regulated under AgNPs treatments. In conclusion, more than the released Ag+, nanoparticle-specific effects are responsible for the toxicity of AgNPs in Arabidopsis thaliana.

Requirement of regulated endocrine-specific protein-18 for development and expression of regulated endocrine-specific protein-18 isoform c in mice.

Regulated endocrine-specific protein-18 (RESP18) is distributed mainly in the peripheral endocrine and neuroendocrine tissues. The expression of RESP18 protein is regulated by physiological factors, such as blood glucose or dopaminergic drugs, but its functions remain unclear. In this study, to explore the biological functions of RESP18 in vivo, we generated RESP18 heterozygous deficient mice, and further found RESP18 was essential for embryonic development. In addition, we cloned a new isoform of mouse RESP18 by reverse transcription-polymerase chain reaction (RT-PCR), and denominated it as RESP18-c. Mouse RESP18-c, by skipping exon4 (43 bp in length), encodes a shorter protein of 120 amino acid residues. The distribution of RESP18-c mRNA is similar with that of RESP18 mRNA in the peripheral tissues and brains of mice.

[New option for gene-targeting vector construction Red/ET recombination].

The study of human new gene's function has become an increasingly active academic field basically relying on the gene knockout (KO) mouse. The construction of targeting vector economically and efficiently has turned into the key step to acquire a KO mouse because of the low efficiency of recombination with traditional constructed targeting vector. For study of the function of new gene-Resp18, we brought in a new DNA engineering platform-Red/ET recombination to construct Resp18 targeting vector. Red/ET recombineering differs from the conventional ways of vector construction (e.g., PCR, restriction enzyme digestion and ligation) and achieves genetic modification by acquisition, insertion, fusion or replacement of the target gene through small fragments mediated homologous recombination. Now Resp18 targeting vectors of three strategies were yielded successfully through two homologous recombination processes of retrieve and neo-targeting. Red/ET recombination has the advantage of getting longer homology regions without mutation, which makes it a new and reliable alternative to the construction of a targeting vector today.