RNase III-mediated silencing of a glucose-dependent repressor in yeast

Members of the RNase III family are found in all species examined with the exception of archaebacteria, where the functions of RNase III are carried out by the bulge-helix-bulge nuclease (BHB). In bacteria, RNase III contributes to the processing of many noncoding RNAs and directly cleaves several cellular and phage mRNAs. In eukaryotes, orthologs of RNase III participate in the biogenesis of many miRNAs and siRNAs, and this biogenesis initiates the degradation or translational repression of several mRNAs. However, the capacity of eukaryotic RNase IIIs to regulate gene expression by directly cleaving within the coding sequence of mRNAs remains speculative. Here we show that Rnt1p, a member of the RNase III family, selectively inhibits gene expression in baker's yeast by directly cleaving a stem-loop structure within the mRNA coding sequence. Analysis of mRNA expression upon the deletion of Rnt1p revealed an upregulation of the glucose-dependent repressor Mig2p. Mig2p mRNA became more stable upon the deletion of Rnt1p and resisted glucose-dependent degradation. In vitro, Rnt1p cleaved Mig2p mRNA and a silent mutation that disrupts Rnt1p signals blocked Mig2p mRNA degradation. These observations reveal a new RNase III-dependent mechanism of eukaryotic mRNA degradation.     

Abscisic acid-triggered guard cell l-cysteine desulfhydrase function and in situ hydrogen sulfide production contributes to heme oxygenase-modulated stomatal closure

Recent studies have demonstrated that hydrogen sulfide (H₂S) produced through the activity of l -cysteine desulfhydrase (DES1) is an important gaseous signaling molecule in plants that could participate in abscisic acid (ABA)-induced stomatal closure. However, the coupling of the DES1/H₂S signaling pathways to guard cell movement has not been thoroughly elucidated. The results presented here provide genetic evidence for a physiologically relevant signaling pathway that governs guard cell in situ DES1/H₂S function in stomatal closure. We discovered that ABA-activated DES1 produces H₂S in guard cells. The impaired guard cell ABA phenotype of the des1 mutant can be fully complemented when DES1/H₂S function has been specifically rescued in guard cells and epidermal cells, but not mesophyll cells. This research further characterized DES1/H₂S function in the regulation of LONG HYPOCOTYL1 (HY1, a member of the heme oxygenase family) signaling. ABA-induced DES1 expression and H₂S production are hyper-activated in the hy1 mutant, both of which can be fully abolished by the addition of H₂S scavenger. Impaired guard cell ABA phenotype of des1/hy1 can be restored by H₂S donors. Taken together, this research indicated that guard cell in situ DES1 function is involved in ABA-induced stomatal closure, which also acts as a pivotal hub in regulating HY1 signaling.     

人胃窦部胃泌素和生长抑素及其相关mRNA表达和定位的研究

目的：了解人胃窦粘膜内胃泌素和生长抑素及其mRNA在细胞内的表达和定位。方法：用免疫细胞化学和原位杂交技术。结果：G细胞内的胃泌素主要位于细胞的基部和侧部,而其mRNA则位于核周和核上区;D细胞内的生长抑素不仅位于细胞的基部,也见于细胞突起,其mRNA则位于核周、核上区以及突起。G、D细胞均有开放型和闭合型。结论：G细胞为内分泌方式,而D细胞在人胃窦部可能存在两种细胞亚群,除旁分泌外,也有内分泌方式。     

Highly sensitive chemiluminescence immunoassay on chitosan membrane modified paper platform using TiO2 nanoparticles/multiwalled carbon nanotubes as label

A highly sensitive chemiluminescence (CL) immunoassay was incorporated into a low‐cost microfluidic paper‐based analytical device (μ‐PAD) to fabricate a facile paper‐based CL immunodevice (denoted as μ‐PCLI). This μ‐PCLI was constructed by covalently immobilizing capture antibody on a chitosan membrane modified μ‐PADs, which was developed by simple wax printing methodology. TiO₂ nanoparticles coated multiwalled carbon nanotubes (TiO₂/MWCNTs) were synthesized as an amplification catalyst tag to label signal antibody (Ab₂). After sandwich‐type immunoreactions, the TiO₂/MWCNTs were captured on the surface of μ‐PADs to catalyze the luminol‐p‐iodophenol‐H₂O₂ CL system, which produced an enhanced CL emission. Using prostate‐specific antigen as a model analyte, the approach provided a good linear response range from 0.001 to 20 ng/mL with a low detection limit of 0.8 pg/mL under optimal conditions. This μ‐PCLI showed good reproducibility, selectivity and stability. The assay results of prostate‐specific antigen in clinical serum samples were in good agreement with that obtained by commercially used electrochemiluminescence methods at the Cancer Research Center of Shandong Tumor Hospital (Jinan, Shandong Province, China). This μ‐PCLI could be very useful to realize highly sensitive, qualitative point‐of‐care testing in developing or developed countries. Copyright © 2013 John Wiley & Sons, Ltd.     

Biosystematic Studies on Adenophora potaninii Korsh. Complex (Campanulaceae). Ⅰ. Phenotypic Plasticity

Phenotypic plasticity is the environmental modification of genotypic expression and an important means by which individual plants respond to environmental heterogeneity. The study of phenotypic plasticity in the genus Adenophora, which is very complicated taxo nomically because of great morphological variation, proves to be helpful in both investigating the phenotypic variation so as to evaluate potential taxonomic value of their characters and providing important sources of information on the variation, adaptation and evolution of the genus. Twenty-three populations representing all the six species in Adenophora potaninii complex were transplanted into the garden. Of them six populations were selected for study ing their performance in the field and in the garden, in addition to cultivation experiment under different treatments. The results show that there exists considerable developmental plasticity in some leaf, floral and capsule characters. In particular, the leaf shape and length of calyx lobe display significant developmental variation with the maximum being three times as great as the minimum, which is noteworthy because they were previously considered as diagnostic. The characters of root, caudex, stem and inflorescence are found to be very plastic, especially the root diameter, the number of stems, stem height and inflorescence length with great environmental plasticity. In addition, the populations from different habi tats show distinct amounts of plasticity. On the contrary, the characters of leaf, floral, cap sule and seed are less influenced by environments. It seems that the considerable variation in the characters of leaf is attributed mainly to genetic differences. Finally, the phenotypic plasticity of morphological characters of A. potaninii complex and its taxonomic significanceis discussed.     

Extraordinary metabolic stability of peptides containing α-aminoxy acids

The metabolic stability of peptides containing a mixed sequence of α-aminoxy acids and α-amino acids is significantly improved compared to peptides composed of only natural α-amino acids. The introduction of an α-aminoxy acid into peptide chain dramatically improves the stability of the amide bonds immediately before and after it. These peptides containing α-aminoxy acids represent excellent structural scaffold for the design of metabolically stable and biologically active peptides.