Studies of nitric oxide over the past two decades have highlighted the fundamental importance of gaseous signaling molecules in biology and medicine. The physiological role of other gases such as carbon monoxide and hydrogen sulfide (H 2 S) is now receiving increasing attention. Here we show that H 2 S is physiologically generated by cystathionine γ-lyase (CSE) and that genetic deletion of this enzyme in mice markedly reduces H 2 S levels in the serum, heart, aorta, and other tissues. Mutant mice lacking CSE display pronounced hypertension and diminished endothelium-dependent vasorelaxation. CSE is physiologically activated by calcium-calmodulin, which is a mechanism for H 2 S formation in response to vascular activation. These findings provide direct evidence that H 2 S is a physiologic vasodilator and regulator of blood pressure.Nitric oxide (NO) and carbon monoxide (CO) are established physiologic messenger molecules, and NO has an important role as an endothelial cell-derived relaxing factor (EDRF) and regulator of blood pressure (1,2). Indirect evidence has implicated another endogenous gasotransmitter, hydrogen sulfide (H 2 S), in similar functions (3-7). H 2 S can be produced by cystathionine γ-lyase (CSE) or cystathionine β-synthase (CBS) (3,4), but definitive evidence for either of these enzymes in the physiologic formation of H 2 S is lacking.To investigate the role of H 2 S as a physiologic vasorelaxant and determinant of blood pressure, we generated mice with a targeted deletion of the gene encoding CSE (8) (fig. S1, A to C). The homozygous (CSE −/− ) and heterozygous (CSE −/+ ) mutant mice were viable, fertile, and indistinguishable from their control wild-type littermates (CSE +/+ ) in terms of growth pattern.

attractive for future grid-level energy storage applications. Metallic Zn, as the ideal anode for AZBs, has the highest theoretical capacity (5851 mAh mL −1 ). It is also non-toxic, non-flammable, abundant, and has good electrical conductivity and water stability. [1][2][3][4][5] However, conventional metallic Zn anodes suffer from severe dendrite formation during cycling, causing serious problems like poor reversibility, voltage hysteresis, increased parasitic reactions, shorting-induced battery failures, and other issues. [1,3,6] These dendritic structures, either rarefied needle, or non-planar platelet deposits, preferentially form at irregular or defective areas of the electrode where the localized current density is highest and the initial nucleation event is most likely, [7] and is exacerbated by cycling at high current densities and capacities. [8,9] Strategies for controlling and suppressing dendritic growth have revolved around manipulating the electrolyte, typically by inclusion of additives, [10][11][12][13][14][15] or by engineering the electrode into a high-surface-area sponge, [16][17][18] or with a protective surface coating, [19] in order to suppress dendrite formation.Despite being one of the most promising candidates for grid-level energy storage, practical aqueous zinc batteries are limited by dendrite formation, which leads to significantly compromised safety and cycling performance. In this study, by using single-crystal Zn-metal anodes, reversible electrodeposition of planar Zn with a high capacity of 8 mAh cm −2 can be achieved at an unprecedentedly high current density of 200 mA cm −2 . This dendrite-free electrode is well maintained even after prolonged cycling (>1200 cycles at 50 mA cm −2 ). Such excellent electrochemical performance is due to single-crystal Zn suppressing the major sources of defect generation during electroplating and heavily favoring planar deposition morphologies. As so few defect sites form, including those that would normally be found along grain boundaries or to accommodate lattice mismatch, there is little opportunity for dendritic structures to nucleate, even under extreme plating rates. This scarcity of defects is in part due to perfect atomic-stitching between merging Zn islands, ensuring no defective shallow-angle grain boundaries are formed and thus removing a significant source of non-planar Zn nucleation. It is demonstrated that an ideal high-rate Zn anode should offer perfect lattice matching as this facilitates planar epitaxial Zn growth and minimizes the formation of any defective regions.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202202552.