Microbial cycling of isoprene, the most abundantly produced biological volatile organic compound on Earth

Isoprene (2-methyl-1,3-butadiene), the most abundantly produced biogenic volatile organic compound (BVOC) on Earth, is highly reactive and can have diverse and often detrimental atmospheric effects, which impact on climate and health. Most isoprene is produced by terrestrial plants, but (micro)algal production is important in aquatic environments, and the relative bacterial contribution remains unknown. Soils are a sink for isoprene, and bacteria that can use isoprene as a carbon and energy source have been cultivated and also identified using cultivation-independent methods from soils, leaves and coastal/marine environments. Bacteria belonging to the Actinobacteria are most frequently isolated and identified, and Proteobacteria have also been shown to degrade isoprene. In the freshwater-sediment isolate, Rhodococcus strain AD45, initial oxidation of isoprene to 1,2-epoxy-isoprene is catalyzed by a multicomponent isoprene monooxygenase encoded by the genes isoABCDEF. The resultant epoxide is converted to a glutathione conjugate by a glutathione S-transferase encoded by isoI, and further degraded by enzymes encoded by isoGHJ. Genome sequence analysis of actinobacterial isolates belonging to the genera Rhodococcus, Mycobacterium and Gordonia has revealed that isoABCDEF and isoGHIJ are linked in an operon, either on a plasmid or the chromosome. In Rhodococcus strain AD45 both isoprene and epoxy-isoprene induce a high level of transcription of 22 contiguous genes, including isoABCDEF and isoGHIJ. Sequence analysis of the isoA gene, encoding the large subunit of the oxygenase component of isoprene monooxygenase, from isolates has facilitated the development of PCR primers that are proving valuable in investigating the ecology of uncultivated isoprene-degrading bacteria

Evidence for Antisense Transcription Associated with MicroRNA Target mRNAs in Arabidopsis

Antisense transcription is a pervasive phenomenon, but its source and functional significance is largely unknown. We took an expression-based approach to explore microRNA (miRNA)-related antisense transcription by computational analyses of published whole-genome tiling microarray transcriptome and deep sequencing small RNA (smRNA) data. Statistical support for greater abundance of antisense transcription signatures and smRNAs was observed for miRNA targets than for paralogous genes with no miRNA cleavage site. Antisense smRNAs were also found associated with MIRNA genes. This suggests that miRNA-associated “transitivity” (production of small interfering RNAs through antisense transcription) is more common than previously reported. High-resolution (3 nt) custom tiling microarray transcriptome analysis was performed with probes 400 bp 5′ upstream and 3′ downstream of the miRNA cleavage sites (direction relative to the mRNA) for 22 select miRNA target genes. We hybridized RNAs labeled from the smRNA pathway mutants, including hen1-1, dcl1-7, hyl1-2, rdr6-15, and sgs3-14. Results showed that antisense transcripts associated with miRNA targets were mainly elevated in hen1-1 and sgs3-14 to a lesser extent, and somewhat reduced in dcl11-7, hyl11-2, or rdr6-15 mutants. This was corroborated by semi-quantitative reverse transcription PCR; however, a direct correlation of antisense transcript abundance in MIR164 gene knockouts was not observed. Our overall analysis reveals a more widespread role for miRNA-associated transitivity with implications for functions of antisense transcription in gene regulation. HEN1 and SGS3 may be links for miRNA target entry into different RNA processing pathways

Comparison Of The Effects Of Patient Controlled Analgesia (Pca) Using Dexmedetomidine And Propofol During Septoplasty Operations: A Randomized Clinical Trial

Introduction Septoplastical surgery to correct septum deviation can be performed under either local or general anesthesia. During local anesthesia, sedation helps to provide minimum anxiety/discomfort. Our aim was to evaluate the effects of patient-controlled analgesia using dexmedetomidine and propofol on sedation level, analgesic requirement, and patient satisfaction. Study design A prospective, randomized-parallel clinical study. Methods Fifty patients undergoing septoplastical surgery at our university hospital were randomized into two groups. A nasopharyngeal cotton tampon soaked in 0.25 % adrenaline solution was placed, and 1 mg midazolam and 1 mcg/kg fentanyl were applied 5 min before the injections of a surgical local anesthetic. Loading dose was 0.5 mg/kg propofol (Group I) and 1 mcg/kg dexmedetomidine (Group II). The sedation was sustained by a bolus dose of 0.2 mg/kg and continuous basal infusion dose of 0.5 mg/kg/h propofol in Group I, or by a bolus dose of 0.05 µg/kg and continuous basal infusion dose of 0.4 mcg/kg/h dexmedetomidine in Group II. The primary outcomes were patient satisfaction via patient-controlled anesthesia and analgesic demand. Secondary outcomes were sedation level of patients under local anesthesia. Results In Group II, SpO2 levels were significantly higher than in Group I. Intraoperative and postoperative analgesic requirements were lower in Group II than in Group I. There were no statistically significant differences in patient satisfaction, hemodynamic parameters, nausea and vomiting between the two groups. Conclusion Dexmedetomidine can be used safely as an analgesic and sedation drug in septoplastic surgery.PubMedWoSScopu