Archaeal and Eukaryotic RNA-Splicing Endonucleases

RNA-splicing endonuclease (EndA) cleaves out introns from archaeal and eukaryotic precursor (pre)-tRNA and is essential for tRNA maturation. In archaeal EndA, the molecular mechanisms underlying complex assembly, substrate recognition, and catalysis have been well understood. Recently, certain studies have reported novel findings including the identification of new subunit types in archaeal EndA structures, providing insights into the mechanism underlying broad substrate specificity. Further, metagenomics analyses have enabled the acquisition of numerous DNA sequences of EndAs and intron-containing pre-tRNAs from various species, providing information regarding the co-evolution of substrate specificity of archaeal EndAs and tRNA genetic diversity, and the evolutionary pathway of archaeal and eukaryotic EndAs. Although the complex structure of the heterothermic form of eukaryotic EndAs is unknown, previous reports regarding their functions indicated that mutations in human EndA cause neurological disorders including pontocerebellar hypoplasia and progressive microcephaly, and yeast EndA significantly cleaves mitochondria-localized mRNA encoding cytochrome b mRNA processing 1 (Cpb1) for mRNA maturation. This mini-review summarizes the aforementioned results, discusses their implications, and offers my personal opinion regarding future directions for the analysis of the structure and function of EndAs

Relaxing and Inhibitory Actions of Pedal Ganglion Extracts on the Anterior Byssus Retractor Muscle of Mytilus

Pedal ganglion homogenates from the bivalve, Mytilus edulis, were subjected to gel filtration and the biological activities of the extracts were assayed on the ABRM of the mussel. The extracts resolved into a catch-relaxing peak and a contraction-inhibiting peak of activities. Relaxation of ACh-induced catch tension in the ABRM by catch-relaxing peak was not affected by pretreatment of the muscle with 10^-5 M FMRFamide, suggesting that the active principle of the peak is not FMRFamide. The relaxation was blocked by 5 x 10^-4 M mersalyl, which suggests that the active substance is neither dopamine nor octopamine. The relaxation was markedly depressed after the muscle had been denervated by treating it with KCl-EGTA solution, suggesting that the substance is not serotonin and that it relaxes the catch tension acting on intramuscular relaxing nerve elements. The relaxing activity of the peak was destroyed by incubating it with a protease, subtilisin. Thus, the active substance in the peak seems to be a peptide which acts presynaptically to increase the release of relaxing transmitter serotonin. The contraction-inhibiting peak also lost its activity when incubated with subtilisin, suggesting that the inhibitory substance in the peak is also a peptide. The substance inhibited not only phasic contraction by repetitive electrical stimulation but also ACh contraction and FMRFamide contraction, which suggests that it acts directly on muscle fibres to inhibit the contractions

Recent Insights Into the Structure, Function, and Evolution of the RNA-Splicing Endonucleases

RNA-splicing endonuclease (EndA) cleaves out introns from archaeal and eukaryotic precursor (pre)-tRNA and is essential for tRNA maturation. In archaeal EndA, the molecular mechanisms underlying complex assembly, substrate recognition, and catalysis have been well understood. Recently, certain studies have reported novel findings including the identification of new subunit types in archaeal EndA structures, providing insights into the mechanism underlying broad substrate specificity. Further, metagenomics analyses have enabled the acquisition of numerous DNA sequences of EndAs and intron-containing pre-tRNAs from various species, providing information regarding the co-evolution of substrate specificity of archaeal EndAs and tRNA genetic diversity, and the evolutionary pathway of archaeal and eukaryotic EndAs. Although the complex structure of the heterothermic form of eukaryotic EndAs is unknown, previous reports regarding their functions indicated that mutations in human EndA cause neurological disorders including pontocerebellar hypoplasia and progressive microcephaly, and yeast EndA significantly cleaves mitochondria-localized mRNA encoding cytochrome b mRNA processing 1 (Cpb1) for mRNA maturation. This mini-review summarizes the aforementioned results, discusses their implications, and offers my personal opinion regarding future directions for the analysis of the structure and function of EndAs

Relapse of Vogt-Koyanagi-Harada Disease during Interferon-α and Ribavirin Therapy in a Case of Chronic Viral Hepatitis C

A 60-year-old woman, who had been diagnosed with and treated for Vogt-Koyanagi-Harada (VKH) disease 17 years before, was receiving pegylated interferon-? and ribavirin therapy for chronic hepatitis C virus. Three weeks after the start of therapy, she complained of visual blurring, eye pain, and an increased hearing loss. Based on a slit lamp and fundus examination, she was diagnosed with a relapse of VKH disease. After discontinuation of the pegylated interferon-α and ribavirin therapy and administration of corticosteroid therapy, her visual acuity returned to 1.0 in both eyes without ocular inflammation, and remained stable thereafter. When interferon therapy is administered to hepatitis C virus patients, those who also have a history of VKH disease must be closely monitored for ophthalmologic complications

Statistical double Lambda hypernuclear formation from Xi(-) absorption at rest in light nuclei

We investigate double Lambda hyperfragment formation from the statistical decay of double Lambda compound nuclei produced in the Xi(-) absorption at rest in the light nuclei C-12, N-14, and O-16. We examine the target and the Lambda Lambda bond energy dependence of the double Lambda hyperfragment formation probabilities, especially of those double hypernuclei observed in experiments. For the 12C (N-14) target, the formation probabilities of 6 He and 10 Be (B-13(Lambda Lambda)) are found to be reasonably large as they are observed in the KEK-E373 (KEK-E176) experiment. By comparison, for the O-16 target, the formation probability of Be-11(Lambda Lambda) is calculated to be small with Delta B-Lambda Lambda consistent with the Nagara event. We also evaluate the formation probability of H-5(Lambda Lambda) from a Xi(-)-He-6 bound state, H-7(Xi)

Optimization of Enzyme-Mediated Calcite Precipitation as a Soil-Improvement Technique : The Effect of Aragonite and Gypsum on the Mechanical Properties of Treated Sand

The effectiveness of magnesium as a substitute material in enzyme-mediated calcite precipitation was evaluated. Magnesium sulfate was added to the injecting solution composed of urea, urease, and calcium chloride. The effect of the substitution on the amount of precipitated materials was evaluated through precipitation tests. X-ray powder diffraction and scanning electron microscopy analyses were conducted to examine the mineralogical morphology of the precipitated minerals and to determine the effect of magnesium on the composition of the precipitated materials. In addition to calcite, aragonite and gypsum were formed as the precipitated materials. The effect of the presence of aragonite and gypsum, in addition to calcite, as a soil-improvement technique was evaluated through unconfined compressive strength tests. Soil specimens were prepared in polyvinyl chloride cylinders and treated with concentration-controlled solutions, which produced calcite, aragonite, and gypsum. The mineralogical analysis revealed that the low and high concentrations of magnesium sulfate effectively promoted the formation of aragonite and gypsum, respectively. The injecting solutions which produced aragonite and calcite brought about a significant improvement in soil strength. The presence of the precipitated materials, comprising 10% of the soil mass within a treated sand, generated a strength of 0.6 MPa