Hysteretic hERG Channel Gating Current Recorded At Physiological Temperature

Cardiac hERG channels comprise at least two subunits, hERG 1a and hERG 1b, and drive cardiac action potential repolarization. hERG 1a subunits contain a cytoplasmic PAS domain that is absent in hERG 1b. The hERG 1a PAS domain regulates voltage sensor domain (VSD) movement, but hERG VSD behavior and its regulation by the hERG 1a PAS domain have not been studied at physiological temperatures. We recorded gating charge from homomeric hERG 1a and heteromeric hERG 1a/1b channels at near physiological temperatures (36 ± 1°C) using pulse durations comparable in length to the human ventricular action potential. The voltage dependence of deactivation was hyperpolarized relative to activation, reflecting VSD relaxation at positive potentials. These data suggest that relaxation (hysteresis) works to delay pore closure during repolarization. Interestingly, hERG 1a VSD deactivation displayed a double Boltzmann distribution, but hERG 1a/1b deactivation displayed a single Boltzmann. Disabling the hERG1a PAS domain using a PAS-targeting antibody similarly transformed hERG 1a deactivation from a double to a single Boltzmann, highlighting the contribution of the PAS in regulating VSD movement. These data represent, to our knowledge, the first recordings of hERG gating charge at physiological temperature and demonstrate that VSD relaxation (hysteresis) is present in hERG channels at physiological temperature.

Operando Investigation of the Locally Enhanced Electric Field Treatment (LEEFT) Harnessing Lightning-Rod Effect for Rapid Bacteria Inactivation

The growth of undesired bacteria causes numerous problems. Here, we show that locally enhanced electric field treatment (LEEFT) can cause rapid bacteria inactivation by electroporation without any side reactions. The bacteria inactivation is studied in situ at the single-cell level on a lab-on-a-chip that has nanowedge-decorated electrodes. Rapid bacteria inactivation occurs specifically at nanowedge tips where the electric field is enhanced due to the lightning-rod effect. The mechanism study shows that the bacteria inactivation is caused by electroporation induced by the locally enhanced electric field. The bacteria inactivation performance depends on the strength of the enhanced electric field instead of the applied voltage, and no ROS generation is detected when >90% bacteria inactivation is achieved. Quick membrane pore closure under moderate LEEFT indicates that electroporation is the predominant mechanism. LEEFT only requires facile treatment to achieve bacteria inactivation, which is safe for treating delicate samples and energy-efficient for large scale applications. The findings in this work can provide strong supports for the future applications of LEEFT.

Visualizing sequential compound fusion and kiss-and-run in live excitable cells

Vesicle fusion is assumed to occur at flat membrane of excitable cells. In live neuroendocrine cells, we visualized vesicle fusion at Ω-shape membrane generated by preceding fusion, termed sequential compound fusion, which may be followed by fusion pore closure, termed compound kiss-and-run. These novel fusion modes contribute to vesicle docking, multi-vesicular release, asynchronous release, and endocytosis. We suggest modifying current models of exo-endocytosis to include these new fusion modes.

Dynamics of Myosin II Filaments during Wound Repair in Dividing Cells

Wound repair of cell membranes is essential for cell survival. Myosin II contributes to wound pore closure by interacting with actin filaments in larger cells; however, its role in smaller cells is unclear. In this study, we observed wound repair in dividing cells for the first time. The cell membrane in the cleavage furrow, where myosin II localized, was wounded by laserporation. Upon wounding, actin transiently accumulated, and myosin II transiently disappeared from the wound site. Ca2+ influx from the external medium triggered both actin and myosin II dynamics. Inhibition of calmodulin reduced both actin and myosin II dynamics. The wound closure time in myosin II-null cells was the same as that in wild-type cells, suggesting that myosin II is not essential for wound repair. We also found that disassembly of myosin II filaments by phosphorylation did not contribute to their disappearance, indicating a novel mechanism for myosin II delocalization from the cortex. Furthermore, we observed that several furrow-localizing proteins such as GAPA, PakA, myosin heavy chain kinase C, PTEN, and dynamin disappeared upon wounding. Herein, we discuss the possible mechanisms of myosin dynamics during wound repair.

Nano-Enhanced Electric-Field Treatment Harnessing Lightning-Rod Effect for Rapid Bacteria Inactivation

The growth of undesired bacteria can cause numerous problems. Seeking effective and sustainable bacteria inactivation approaches is an everlasting effort. Here, we show that nano-enhanced electric field treatment (NEEFT) can cause rapid bacteria inactivation with a lower applied voltage than bulk EFT. A lab-on-a-chip with nanowedge-modified electrodes is developed, and the bacteria inactivation in NEEFT is visualized and studied in real-time at a single-cell level. Rapid bacteria inactivation (~ 1 ms) occurs specifically at nanowedge tips where the electric field is enhanced due to the lightning-rod effect. Nanowedges with a high aspect ratio are critical for bacteria inactivation. NEEFT works for both immobilized and free-moving cells, where the free-moving cells will be first attracted to the nanowedge tips followed by rapid inactivation. The mechanism study shows that the bacteria inactivation is caused by electroporation induced by the nano-enhanced electric field. The bacteria inactivation performance depends on the strength of the enhanced electric field instead of the applied voltage. Quick pore closure and membrane recovery under moderate NEEFT indicate that electroporation is the predominant mechanism. NEEFT only requires facile treatment to achieve bacteria inactivation, which is safe for treating delicate samples and energy-efficient for large scale applications. It is also expected to find applications for targeted cell inactivation.

Application of Melaleuca alternifolia essential oils associated with phototherapy in acneic inflammatory injury

Objective: The use of natural products for diverse affections treatments is something aged, described since the man’s cradle, which made use of plants for wounds and natural disorders treatments. That said, the assignment objective is to expose the presentation of an experience report in case of an inflammatory process of bacteria origin due an acne treated with melaleuca essential oil associated with the photo dynamics therapy. Methods: For such, the specific spot to be worked on was sanitized with a cleaning solution and after it was hydrated with an invigorating solution. It was used on the spot 20 µL of melaleuca (Melaleuca aternifólia) essential oil and also it was performed a circular massage to spread the product. Over the spot was fell upon a blue intensity light (± 550nm) focusing on it. Results: After 5 minutes exhibition, edema decreased and pore closure was observed due to an absence of intense fushing, going intense to slight., edema decreased and pore closure. In brief, it is possible to say that the malaleuca essential oil association with application of photo dynamic therapy has the remedial potencial on facing inflammatory and infectious processes caused by acne. Conclusion: Lastly, the propagation of cases reports are of crucial importance, since that comparisons with the literature can lend to new therapies alternatives.