Cobalt oxyhydroxide nanosheet-modulated ratiometric fluorescence platform for the selective detection of malachite green in fish.

A ratiometric fluorescence platform was developed based on the cobalt oxyhydroxide (CoOOH) nanosheet-modulated fluorescence response of blue emissive copper nanoclusters (Cu NCs) and yellow emissive o-phenylenediamine (OPD). CoOOH nanosheets showed dual function of strong absorption and oxidation ability, which can effectively quench the blue fluorescence of Cu NCs, with an excitation and emission peak maximum at 390 and 450 nm, respectively , and transfer the OPD into yellow fluorescence products, with an excitation and emission peak maximum at 390 and 560 nm, respectively. Upon introducing butyrylcholinesterase (BChE) and its substrates, CoOOH nanosheets were decomposed into Co2+, and malachite green (MG) showed strong inhibition ability to this  process. This resulted in the obvious difference on the ratio of blue and yellow fluorescence recorded on the system in the presence and absence of MG, which was utilized for the quantitative detection of MG, with a limit of detection of 0.140 µM and a coefficient of variation of 3.5%. The fluorescence ratiometric assay showed excellent detection performances in practical sample analysis.

Transcriptomic analysis reveals process of autolysis of Kluyveromyces marxianus in vacuum negative pressure and the higher temperature

Kluyveromyces marxianus is expected to be used in the production of yeast extracts due to its good fermentation ability and nutritional properties. Yeast autolysis is a key process to produce yeast extract and vacuum negative pressure stress can be used as an effective way to assist autolysis. However, the molecular mechanism of initiating Kluyveromyces marxianus autolysis induced by vacuum negative pressure and the higher temperature is still unclear. In this study, RNA-seq technology was performed mainly to analyze autolytic processes in Kluyveromyces marxianus strains. Considerable differentially expressed genes (DEGs) of downregulation were significantly enriched in 7 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to synthesis and transport of RNA and ribosome, which indicated that abnormal protein translations had already occurred in autolytic process. Interestingly, due to obvious change of related DEGs, endoplasmic reticulum-associated degradation (ERAD) and autophagy were activated and cell wall integrity pathway was hindered. Under the continuous influence of the external stress environment, the long-term changes of the above pathways triggered a vicious circle of gradual damage to yeast cells, which is the main cause of yeast autolysis. These results may provide important clues for the in-depth interpretation of the yeast autolytic mechanism.(AU)

Transcriptomic analysis reveals process of autolysis of Kluyveromyces marxianus in vacuum negative pressure and the higher temperature.

Kluyveromyces marxianus is expected to be used in the production of yeast extracts due to its good fermentation ability and nutritional properties. Yeast autolysis is a key process to produce yeast extract and vacuum negative pressure stress can be used as an effective way to assist autolysis. However, the molecular mechanism of initiating Kluyveromyces marxianus autolysis induced by vacuum negative pressure and the higher temperature is still unclear. In this study, RNA-seq technology was performed mainly to analyze autolytic processes in Kluyveromyces marxianus strains. Considerable differentially expressed genes (DEGs) of downregulation were significantly enriched in 7 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to synthesis and transport of RNA and ribosome, which indicated that abnormal protein translations had already occurred in autolytic process. Interestingly, due to obvious change of related DEGs, endoplasmic reticulum-associated degradation (ERAD) and autophagy were activated and cell wall integrity pathway was hindered. Under the continuous influence of the external stress environment, the long-term changes of the above pathways triggered a vicious circle of gradual damage to yeast cells, which is the main cause of yeast autolysis. These results may provide important clues for the in-depth interpretation of the yeast autolytic mechanism.