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Flexible bronchoscopy is useful and safe in retrieving airway foreign bodies in children. With skilled personnel and perfect equipments, flexible bronchoscopy could be considered as the first choice for the removal of airway foreign body.

Both glucose and ABA play crucial roles in the regulation of seed germination and post-germination development. In Arabidopsis thaliana, up-regulation of ABA biosynthesis is suggested as one of the possible mechanisms mediating the glucose-induced delay in seed germination. Since the endogenous ABA level is controlled by the equilibrium between ABA biosynthesis and catabolism, we investigated how this equilibrium is related to the regulation of seed germination by glucose in rice. When ABA biosynthesis was inhibited by nordihydroguaiaretic acid (NDGA), an inhibitor of the ABA anabolic enzyme 9-cis-epoxycarotenoid dioxygenase (NCED), rice seed germination showed no response. In contrast, inhibition of ABA catabolism by diniconazole significantly arrested seed germination, suggesting that the regulation of ABA catabolism plays a major role. Further experiments indicated that the expression of OsABA8ox3, a key gene in ABA catabolism and encoding ABA 8'-hydroxylase in rice, was significantly increased during the first 6 h of imbibition, which was consistent with the decline of ABA content in the imbibed seeds. Expression of OsABA8ox genes, especially OsABA8ox2 and OsABA8ox3, was sensitively suppressed in the presence of exogenously supplied glucose. In contrast, the expression profiles of OsNCED genes that control the limiting step of ABA biosynthesis showed no significant changes in response to low levels of glucose. Our results demonstrated that the glucose-induced delay of seed germination is a result of the suppression of ABA catabolism rather than any enhancement of ABA biosynthesis during rice seed germination.

DNA methylation-dependent heterochromatin formation is a conserved mechanism of epigenetic silencing of transposons and other repeat elements in many higher eukaryotes. Genes adjacent to repetitive elements are often also subjected to this epigenetic silencing. Consequently, plants have evolved antisilencing mechanisms such as active DNA demethylation mediated by the REPRESSOR OF SILENCING 1 (ROS1) family of 5-methylcytosine DNA glycosylases to protect these genes from silencing. Some transposons and other repeat elements have found residence in the introns of genes. It is unclear how these intronic repeat elements-containing genes are regulated. We report here the identification of ANTI-SILENCING 1 (ASI1), a bromo-adjacent homology domain and RNA recognition motif-containing protein, from a forward genetic screen for cellular antisilencing factors in Arabidopsis thaliana. ASI1 is required to prevent promoter DNA hypermethylation and transcriptional silencing of some transgenes. Genome-wide DNA methylation analysis reveals that ASI1 has a similar role to that of the histone H3K9 demethylase INCREASE IN BONSAI METHYLATION 1 (IBM1) in preventing CHG methylation in the bodies of thousands of genes. We found that ASI1 is an RNA-binding protein and ensures the proper expression of IBM1 full-length transcript by associating with an intronic heterochromatic repeat element of IBM1. Through mRNA sequencing, we identified many genes containing intronic transposon elements that require ASI1 for proper expression. Our results suggest that ASI1 associates with intronic heterochromatin and binds the gene transcripts to promote their 3′ distal polyadenylation. The study thus reveals a unique mechanism by which higher eukaryotes deal with the collateral effect of silencing intronic repeat elements.DNA methylome | ChIP | gene expression I n higher eukaryotes including plants, DNA methylation is an important epigenetic mark that silences transposons and other repetitive elements. In Arabidopsis thaliana, DOMAINS REARRANGED METHYLASE 2 (DRM2) catalyzes de novo DNA methylation in all cytosine contexts including CG, CHG, and CHH (H represents A, T, or G) (1), through the RNAdirected DNA methylation pathway (RdDM) (2-9). At the same time, preexisting DNA methylation in plants can be pruned by enzymatic excision that is catalyzed by a subfamily of bifunctional DNA glycosylases represented by REPRESSOR OF SI-LENCING 1 (ROS1) and DEMETER (DME) (10)(11)(12)(13)(14). Following the enzymatic removal of 5-methylcytosine, the resultant singlenucleotide gap is filled with an unmodified cytosine through the DNA base excision repair pathway (15,16).Cytosine methylation and demethylation are both tightly linked with histone modifications. Increased DNA methylation was observed in an A. thaliana mutant defective in INCREASED DNA METHYLATION 1 (IDM1), an acetyltransferase that catalyzes acetylation of histone H3 lysine 18 (H3K18) and lysine 23 (H3K23) necessary for subsequent DNA demethylation and prevention of transcriptional silencing (17). In A...