Permeability-Controllable Potentiometric Fluorescent Probes Enable Visually Discriminating Near-Zero and Normal Situations of Cell Membrane Potential

Long-Chain Fluorescent Probe for Straightforward and Nondestructive Staining Mitochondria in Fixed Cells and Tissues

Normally, small-molecule fluorescent probes dependent on the mitochondrial membrane potential (MMP) are invalid for fixed cells and tissues, which limits their clinical applications when the fixation of pathological specimens is imperative. Given that mitochondrial morphology is closely associated with disease, we developed a long-chain mitochondrial probe for fixed cells and tissues, DMPQ-12, by installing a C12-alkyl chain into the quinoline moiety. In fixed cells stained with DMPQ-12, filament mitochondria and folded cristae were observed with confocal and structural illumination microscopy, respectively. In titration test with three major phospholipids, DMPQ-12 exhibited a stronger binding force to mitochondria-exclusive cardiolipin, revealing its targeting mechanism. Moreover, mitochondrial morphological changes in the three lesion models were clearly visualized in fixed cells. Finally, by DMPQ-12, three kinds of mitochondria with different morphologies were observed in situ in fixed muscle tissues. This work breaks the conventional concept that organic fluorescent probes only stain mitochondria with normal membrane potentials and opens new avenues for comprehensive mitochondrial investigations in research and clinical settings.

The antibacterial mechanism of compound preservatives combined with low voltage electric fields on the preservation of steamed mussels (Mytilus edulis) stored at ice-temperature

Mussels are a kind of economically valuable ocean bivalve shellfish. It has a short harvest period and is susceptible to contamination during storage and processing. Having proper preservation methods is critical to prevent quality deterioration. However, the effect of low voltage variable frequency electric field and compound preservative on the freshness of steamed mussels in ice-temperature storage are still unknown. We utilized the method of coefficient variation weighting to calculate the overall scores of steamed mussels stored under different preservation conditions. The protein physicochemical properties of samples, the growth curves of two dominant spoilage bacteria; Bacillus subtilis and Pseudomonas in the mussels as well as the Structural changes of the cell membranes were mensurated. The results show that compared with the preservative group and the low voltage variable frequency electric field group, the compound preservatives combined with the electric field group had the highest overall score and thus the best preservation effect. Compared with the blank group, the total sulfhydryl content and myogenic fibrin content of the combined group decreased at the slowest rate, 19.46%, and 44.92%, respectively. The hydrophobicity of the protein surface increased by only 5.67%, with the best water retention, indicating that the samples of the combined group had the least protein deterioration in the combined group. The inhibition mechanism of the combined group inhibited the growth of two dominant spoilage bacteria: Bacillus subtilis and Pseudomonas, in the mussels, destroying the integrity of the cell membrane structure and changing the cell morphology. Overall, we found that the combination of the composite preservatives and the low voltage variable frequency electric field can maintain the best quality of steamed mussels during ice-temperature storage and slow down the rate of protein deterioration during storage. This study proposed a new method of mussel preservation, which provides a new idea for the application of low voltage variable frequency electric field and compound preservative in the preservation of aquatic products.