AIP1 acts with cofilin to control actin dynamics during epithelial morphogenesis

During epithelial morphogenesis, cells not only maintain tight adhesion for epithelial integrity but also allow dynamic intercellular movement to take place within cell sheets. How these seemingly opposing processes are coordinated is not well understood. Here, we report that the actin disassembly factors AIP1 and cofilin are required for remodeling of adherens junctions (AJs) during ommatidial precluster formation in Drosophila eye epithelium, a highly stereotyped cell rearrangement process which we describe in detail in our live imaging study. AIP1 is enriched together with F-actin in the apical region of preclusters, whereas cofilin displays a diffuse and uniform localization pattern. Cofilin overexpression completely rescues AJ remodeling defects caused by AIP1 loss of function, and cofilin physically interacts with AIP1. Pharmacological reduction of actin turnover results in similar AJ remodeling defects and decreased turnover of E-cadherin, which also results from AIP1 deficiency, whereas an F-actin-destabilizing drug affects AJ maintenance and epithelial integrity. Together with other data on actin polymerization, our results suggest that AIP1 enhances cofilin-mediated actin disassembly in the apical region of precluster cells to promote remodeling of AJs and thus intercellular movement, but also that robust actin polymerization promotes AJ general adhesion and integrity during the remodeling process.     

Roles of DCL4 and DCL3b in rice phased small RNA biogenesis

Higher plants have evolved multiple proteins in the RNase III family to produce and regulate different classes of small RNAs with specialized molecular functions. In rice (Oryza sativa), numerous genomic clusters are targeted by one of two microRNAs (miRNAs), miR2118 and miR2275, to produce secondary small interfering RNAs (siRNAs) of either 21 or 24 nucleotides in a phased manner. The biogenesis requirements or the functions of the phased small RNAs are completely unknown. Here we examine the rice Dicer-Like (DCL) family, including OsDCL1, -3a, -3b and -4. By deep sequencing of small RNAs from different tissues of the wild type and osdcl4-1, we revealed that the processing of 21-nucleotide siRNAs, including trans-acting siRNAs (tasiRNA) and over 1000 phased small RNA loci, was largely dependent on OsDCL4. Surprisingly, the processing of 24-nucleotide phased small RNA requires the DCL3 homolog OsDCL3b rather than OsDCL3a, suggesting functional divergence within DCL3 family. RNA ligase-mediated 5' rapid amplification of cDNA ends and parallel analysis of RNA ends (PARE)/degradome analysis confirmed that most of the 21- and 24-nucleotide phased small RNA clusters were initiated from the target sites of miR2118 and miR2275, respectively. Furthermore, the accumulation of the two triggering miRNAs requires OsDCL1 activity. Finally, we show that phased small RNAs are preferentially produced in the male reproductive organs and are likely to be conserved in monocots. Our results revealed significant roles of OsDCL4, OsDCL3b and OsDCL1 in the 21- and 24-nucleotide phased small RNA biogenesis pathway in rice.     

Tea epigallocatechin-3-gallate increases 8-isoprostane level and induces caudal regression in developing rat embryos

Tea is the most common beverage after water. Concerns have been raised about the safety of tea during pregnancy, especially for embryo development. We aimed at studying the effects of active tea components on developing embryos by in vitro rat embryo culture. Rat embryos during early organogenesis were cultivated in serum supplemented with one of the tea catechins. Developmental hallmarks and malformations (Mal) in the developing embryos were compared and evaluated by a standard morphological scoring system. The embryotoxicity of each tea catechin was classified according to the European Center for the Validation of Alternative Methods. Cell viability was assessed by supervital dye staining, apoptosis by TUNEL assay, and peroxidation by the 8-isoprostane EIA method. We found that (+)-catechin had the least effect on developing embryos (Mal(50)=715.1 mg/L; IC50(Mal)=435 mg/L), whereas (-)-epigallocatechin gallate had the most adverse effect (Mal(50)=54.2 mg/L; IC50(Mal)=45.8 mg/L). The major malformation in affected embryos included caudal retardation with abnormal axial flexion and delayed hind-limb formation. All catechins were classified as nonembryotoxic except (-)-epigallocatechin gallate, which was classified as weakly embryotoxic. With (-)-epigallocatechin gallate, increased numbers of nonviable and apoptotic cells in the malformed embryos were associated with increased embryo 8-isoprostane.     

Effects of elevated atmospheric CO2 on soil enzyme activities at different nitrogen application treatments

It has been predicted that elevated atmospheric CO₂ will increase enzyme activity as a result of CO₂-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO₂ on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO₂ concentrations (580±60) and (380±40) μmol·mol^-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm^-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO₂ β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO₂ significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO₂ only had significant higher effects (P < 0.05) at high N application rates. Under different CO₂ concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO₂ concentration decreased with N fertilization, while it increased at elevated CO₂ concentration. In addition, invertase and acid phosphatase activities at elevated CO₂ concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO₂ concentration. For urease activity, at ambient CO₂ concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO₂ concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO₂ increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO₂ led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO₂ increased plant photosynthesis, thereby increasing plant-derived soil enzymes.     

Effects of elevated atmospheric CO2 on soil enzyme activities at different nitrogen application treatments

It has been predicted that elevated atmospheric CO₂ will increase enzyme activity as a result of CO₂-induced carbon entering the soil. The objective of this study was to investigate the effects of elevated atmospheric CO₂ on soil enzyme activities under a rice/wheat rotation. This experiment was conducted in Wuxi, Jiangsu, China as part of the China FACE (Free Air Carbon Dioxide Enrichment) Project. Two atmospheric CO₂ concentrations (580±60) and (380±40) μmol·mol^-1) and three N application treatments (low-150, normal-250 and high-350 kg N·hm^-2) were included. Soil samples (0-10 cm) were collected for analysis of β-glucosidase, invertase, urease, acid phosphates and β-glucosaminidase activities. The results revealed that with elevated atmospheric CO₂ β-glucosidase activity significantly decreased (P < 0.05) at low N application rates; had no significant effect with a normal N application rate; and significantly increased (P < 0.05) with a high N application rate. For urease activity, at low and normal N application rates (but not high N application rate), elevated atmospheric CO₂ significantly increased (P < 0.05) it. With acid phosphatase elevated atmospheric CO₂ only had significant higher effects (P < 0.05) at high N application rates. Under different CO₂ concentration, effects of N fertilization are also different. Soil β-glucosidase activity at ambient CO₂ concentration decreased with N fertilization, while it increased at elevated CO₂ concentration. In addition, invertase and acid phosphatase activities at elevated CO₂ concentration, significantly increased (P < 0.05) with N treatments, but there was no effect with the ambient CO₂ concentration. For urease activity, at ambient CO₂ concentration, N fertilization increased it significantly (P < 0.05), whereas at elevated CO₂ concentration it was not significant. Additionally, with β-glucosaminidase activity, there were no significant effects from N application. In general, then, elevated atmospheric CO₂ increased soil enzyme activity, which may be attributed to the following two factors: (1) elevated atmospheric CO₂ led to more plant biomass in the soil, which in turn stimulated soil microbial biomass and activity; and (2) elevated atmospheric CO₂ increased plant photosynthesis, thereby increasing plant-derived soil enzymes.     

Studies on the Chemical Constituents of Limonium aureum (L.) Hill

Five different crystals have been obtained for the first time from the aerial parts of Limonium aureum (L.)Hill ex kuntze. They were identified as follows: (Ⅰ) homoeriodictyol, (Ⅱ) naringenin, (Ⅲ) eriodictyol (Ⅳ) myricetin-3-O-β-D-glucoside and (Ⅴ) myricetin-3-O-β-D-galactoside.     

Coordinated regulation of vascular endothelial cell growth and prostacyclin production by epidermal growth factor: Evidence of clonal variations among rat aortic endothelial cells

Summary Rat aortic endothelial cells were found to exhibit clonal variations in response to EGF stimulation in cell growth and prostacyclin synthesis. EGF-induced growth and prostacyclin synthesis appeared to be regulated in a coordinated manner in that a clone with a higher response to EGF growth stimulation also exhibited a higher response to EGF-stimulated prostacyclin synthesis. This observation implys a possible involvement of prostacyclin synthesis in some of the biological effects of EGF on vascular endothelial cells.