LncRNA OIP5-AS1/cyrano sponges RNA-binding protein HuR

The function of the vast majority of mammalian long noncoding (lnc) RNAs remains unknown. Here, analysis of a highly abundant mammalian lncRNA, OIP5-AS1, known as cyrano in zebrafish, revealed that OIP5-AS1 reduces cell proliferation. In human cervical carcinoma HeLa cells, the RNA-binding protein HuR, which enhances cell proliferation, associated with OIP5-AS1 and stabilized it. Tagging OIP5-AS1 with MS2 hairpins to identify associated microRNAs revealed that miR-424 interacted with OIP5-AS1 and competed with HuR for binding to OIP5-AS1. We further identified a ‘sponge’ function for OIP5-AS1, as high levels of OIP5-AS1 increased HuR-OIP5-AS1 complexes and prevented HuR interaction with target mRNAs, including those that encoded proliferative proteins, while conversely, lowering OIP5-AS1 increased the abundance of HuR complexes with target mRNAs. We propose that OIP5-AS1 serves as a sponge or a competing endogenous (ce)RNA for HuR, restricting its availability to HuR target mRNAs and thereby repressing HuR-elicited proliferative phenotypes.     

Esterases in mycobacteria

Esterases ofMycobacterium phlei (acetic ester acetyl hydrolase E.C.3.1.6 and carboxylic esterhydrolase E.C.3.1.1.1.) obtained after separation on Sephadex G-100 can be temporarily, for a short time interval, activated by adding calcium ions. The activation of esterases isolated from cells was non-repeteable, whereas the temporary activation of esterases from the culture filtrate could be repeated by increasing concentrations of calcium ions. However, the value of activation gradually decreased. Similarly with calcium ions strontium ions were also effective, however, higher concentrations were required and the activation was non-repeatable. Magnesium ions were practically without any effect. Possible mechanisms of the temporary activation of esterases ofMycobacterium phlei are discussed.     

Esterases in mycobacteria

Esterases ofMycobacterium phlei isolated by means of Sephadex G-100 chromatography could be temporarily activated by adding calcium ions. This activation could not be brought about in crude enzyme preparations from cells or in crude extracts from the culture filtrate. It was demonstrated that compounds (or a compound) without the esterase activity isolated after the separation of crude enzyme preparations on Sephadex G-100 (peak C) are responsible for the above difference. It was found that the suppression by compounds from the “C peak” of the temporary activation of esterases with calcium ions depends most probably on the ratio of these compounds to the quantity of the enzyme rather than on their concentration. In addition, the compounds of the C peak themselves were found to activate esterases. The activation was lower than the temporary activation with calcium ions. The possible mechanisms of the temporary activation of esterases and the importance of these findings, from the point of view of regulation of the activity of esterases during submerged cultivation ofMycobacterium phlei, are discussed.     

Utilization of a lipid substrate for submerged fermentation ofStreptomyces albus

When investigating the effect of aeration on the utilization of a lipid substrate from the cultivation broth and production of salinomycin inStreptomyces albus it was demonstrated that a higher aeration results in a better utilization of soya oil and a higher production of the antibiotic.     

Propionate and the production of monensins inStreptomyces cinnamonensis

Variants resistant to propionate were prepared from a mutant strain of Streptomyces cinnamonensis producing predominantly monensin A. Using selected resistants the production of monensins (in media with higher concentrations of propionate) was examined. Stimulation of monensin synthesis by propionate was observed with 70% of the resistants studied. Propionate did not influence the ratio between monensin A and B production.     

Shimiella gen. nov. and Shimiella gracilenta sp. nov. (Dinophyceae,Kareniaceae), a Kleptoplastidic Dinoflagellate from Korean Waters and its Survival under Starvation

A small dinoflagellate, ~13 μm in cell length, was isolated from Jinhae Bay, Korea. Light microscopy showed that it was similar to the kleptoplastidic dinoflagellate Gymnodinium gracilentum nom. inval. rDNA sequences were obtained and its anatomy and morphology described using light and scanning and transmission electron microscopy. Phylogenetic analyses indicated that it belonged to the family Kareniaceae. However, its large subunit (LSU) rDNA sequences were 5.2–9.5% different from those of the other five genera in the family, and its clade was clearly divergent from that of each genus. Its overall morphology was different from those of the other five genera in the family and from Gymnodinium. Unlike Gymnodinium, this dinoflagellate did not have a horseshoe‐shaped apical groove, nuclear envelope chambers, or a nuclear fibrous connective (NFC). It had an apical line of narrow amphiesmal vesicles and an elongated apical furrow crossing the apex. Cells were covered with polygonal amphiesmal vesicles arranged in 16 rows. Starved cells did not contain their own plastids, eyespots, pyrenoids, peridinin, or fucoxanthin. However, they could survive without added prey for approximately one month using chloroplasts from the cryptophyte prey Teleaulax amphioxeia, indicating kleptoplastidy. Because this taxon is genetically distinct at the generic rank from the other genera in Kareniaceae, it is placed in Shimiella gen. nov., and because G. gracilentum was invalid, the new bionomial S. gracilenta sp. nov. is proposed.     

Kojic acid–amino acid conjugates as tyrosinase inhibitors

Kojic acid (KA), a well known tyrosinase inhibitor, has insufficient inhibitory activity and stability. We modified KA with amino acids and screened their tyrosinase inhibitory activity. Among them, kojic acid–phenylalanine amide (KA-F-NH₂) showed the strongest inhibitory activity, which was maintained for over 3 months at 50 °C, and acted as a noncompetitive inhibitor as determined by kinetic analysis. It also exhibited dopachrome reducing activity. We also propose a new tyrosinase inhibition mechanism based on the docking simulation data.