Nanobar Array Assay Revealed Complementary Roles of BIN1 Splice Isoforms in Cardiac T-Tubule Morphogenesis.

Bridging integrator-1 (BIN1) is a family of banana-shaped molecules implicated in cell membrane tubulation. To understand the curvature sensitivity and functional roles of BIN1 splicing isoforms, we engineered vertical nanobars on a cell culture substrate to create high and low curvatures. When expressed individually, BIN1 isoforms with phosphoinositide-binding motifs (pBIN1) appeared preferentially at high-curvature nanobar ends, agreeing well with their membrane tubulation in cardiomyocytes. In contrast, the ubiquitous BIN1 isoform without phosphoinositide-binding motif (uBIN1) exhibited no affinity to membranes around nanobars but accumulated along Z-lines in cardiomyocytes. Importantly, in pBIN1-uBIN1 coexpression, pBIN1 recruited uBIN1 to high-curvature membranes at nanobar ends, and uBIN1 attached the otherwise messy pBIN1 tubules to Z-lines. The complementary cooperation of BIN1 isoforms (comboBIN1) represents a novel mechanism of T-tubule formation along Z-lines in cardiomyocytes. Dysregulation of BIN1 splicing, e.g., during myocardial infarction, underlied T-tubule disorganization, and correction of uBIN1/pBIN1 stoichiometry rescued T-tubule morphology in heart disease.

[Experimental study on high alloy steel sample by laser-induced breakdown spectroscopy].

The laser-induced breakdown spectroscopy (LIBS) technique is a fast, non-contact method with no need for any sample preparation, and can be carried out under various atmospheric conditions. These properties make LIBS applicable to process control in metallurgy. In the present paper, a series of high alloy steel GBW01605-01609 samples were determined by laser induced plasma spectroscopy, based on a Nd : YAG Q-switched solid laser with wavelength 1 064 nm as an excitation source and CCD as detector. Experimental study on the interaction between laser and high alloy steel samples was completed. The effects on LIBS in high alloy steel such as observation distance and laser power density were systematically studied. The time-resolved spectrum of LIBS was also investigated. The optimum experiment conditions for the application of LIBS to the trace analysis in high alloy steel were obtained firstly.