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Serotonin (5‐hydroxytryptamine [5‐HT]) receptors (5‐HTRs) mediate neuroendocrine signaling via interactions with the ligand serotonin (5‐HT). The 5‐HT signaling system has been well studied in vertebrates, but rarely known in invertebrate animals, especially in the marine invertebrates. In this study, we identified and characterized a novel 5‐HTR from the sea cucumber Apostichopus japonicus (Aj5‐HT4/6). The cloned Aj5‐HT4/6 open reading frame comprised 1290 bp and encoded 429 amino acids. Bioinformatic analysis of the receptor indicated that it was a member of the class A of the G protein‐coupled receptor family. Further experiments using Aj5‐HT4/6‐transfected HEK293 cells demonstrated that treatment with 5‐HT could induce rapid internalization of Aj5‐HT4/6 fused with enhanced green fluorescent protein from the cell surface into the cytoplasm and triggered a significant increase in levels of the second messenger cAMP as well as mitogen‐activated protein kinase phosphorylation in a 5‐HT dose‐dependent manner. Quantitative real time‐polymerase chain reaction demonstrated that Aj5‐HT4/6 was predominantly expressed in the muscle and respiratory tree, and its expression was significantly decreased during estivation. Taken together, these results imply that Aj5‐HT4/6 is potentially involved in the movement and metabolism of the sea cucumber. Research Highlights: A novel 5‐hydroxytryptamine receptor (5‐HTR) (Aj5‐HT4/6) was identified in sea cucumber with 1290 bp open reading frame.The bioinformatic and pharmacological analyses indicated that Aj5‐HT4/6 was Gs protein coupled GPCR and classified into 5‐HTR class 4 or 6 family.The transcriptional investigation of Aj5‐HT4/6 suggested its functional involvement in the movement and metabolism. [ABSTRACT FROM AUTHOR]

Two new CdII MOFs, namely, two‐dimensional (2D) poly[[[μ2‐1,4‐bis(1H‐benzimidazol‐1‐yl)butane](μ2‐heptanedioato)cadmium(II)] tetrahydrate], {[Cd(C7H10O4)(C18H18N4)]·4H2O}n or {[Cd(Pim)(bbimb)]·4H2O}n (1), and 2D poly[diaqua[μ2‐1,4‐bis(1H‐benzimidazol‐1‐yl)butane](μ4‐decanedioato)(μ2‐decanedioato)dicadmium(II)], [Cd2(C10H16O4)2(C18H18N4)(H2O)2]n or [Cd(Seb)(bbimb)0.5(H2O)]n (2), have been synthesized hydrothermally based on the 1,4‐bis(1H‐benzimidazol‐1‐yl)butane (bbimb) and pimelate (Pim2−, heptanedioate) or sebacate (Seb2−, decanedioate) ligands. Both MOFs were structurally characterized by single‐crystal X‐ray diffraction. In 1, the CdII centres are connected by bbimb and Pim2− ligands to generate a 2D sql layer structure with an octameric (H2O)8 water cluster. The 2D layers are further connected by O—H...O hydrogen bonds, resulting in a three‐dimensional (3D) supramolecular structure. In 2, the CdII centres are coordinated by Seb2− ligands to form binuclear Cd2 units which are linked by bbimb and Seb2− ligands into a 2D hxl layer. The 2D layers are further connected by O—H...O hydrogen bonds, leading to an 8‐connected 3D hex supramolecular network. IR and UV–Vis spectroscopy, thermogravimetric analysis and solid‐state photoluminescence analysis were carried out on both MOFs. Luminescence sensing experiments reveal that both MOFs have good selective sensing towards Fe3+ in aqueous solution. [ABSTRACT FROM AUTHOR]

Developing high‐performance non‐noble‐metal electrocatalysts for the hydrogen evolution reaction (HER), which can be stably operated under various conditions is highly required in realistic production. In this work, a hierarchical architecture consisting of MoS2 and Co9S8 anchored on a reduced graphene oxide (rGO) substrate was first synthesized, then by introducing blank graphene oxide (GO) and multi‐walled carbon nanotubes (CNTs), interconnected three‐dimensional (3D) composite aerogels with high conductivity were obtained, showing a high activity for the HER, with low overpotentials (η10) at about 90 mV (0.5 M H2SO4), 176 mV (1.0 M PBS), and 102 mV (1.0 M KOH). The high performance might be caused by special hierarchical 3D structures maximally exposing the active edges of both MoS2 and Co9S8. Additionally, 3D MoS2/Co9S8/rGO‐CNTs showed a superior stability and could work stably under different conditions for more than 20 h or 1000 cycles, which is attributed to the good crystallinity after annealing, the highly symmetrical structures between Co9S8 and MoS2, and robust protection provided by the 3D carbon substrate. The results presented herein may provide an effective way to develop non‐noble‐metal electrocatalysts for different fields including the HER. A three‐dimensional composite is synthesized by a simple two‐step method and applied as a highly active pH‐universal electrocatalyst for the hydrogen evolution reaction. The material is stable in acid, neutral, and alkaline media. [ABSTRACT FROM AUTHOR]

Two new CdII MOFs, namely, two‐dimensional (2D) poly[[[μ2‐1,4‐bis(1H‐benzimidazol‐1‐yl)butane](μ2‐heptanedioato)cadmium(II)] tetrahydrate], {[Cd(C7H10O4)(C18H18N4)]·4H2O}n or {[Cd(Pim)(bbimb)]·4H2O}n (1), and 2D poly[diaqua[μ2‐1,4‐bis(1H‐benzimidazol‐1‐yl)butane](μ4‐decanedioato)(μ2‐decanedioato)dicadmium(II)], [Cd2(C10H16O4)2(C18H18N4)(H2O)2]n or [Cd(Seb)(bbimb)0.5(H2O)]n (2), have been synthesized hydrothermally based on the 1,4‐bis(1H‐benzimidazol‐1‐yl)butane (bbimb) and pimelate (Pim2−, heptanedioate) or sebacate (Seb2−, decanedioate) ligands. Both MOFs were structurally characterized by single‐crystal X‐ray diffraction. In 1, the CdII centres are connected by bbimb and Pim2− ligands to generate a 2D sql layer structure with an octameric (H2O)8 water cluster. The 2D layers are further connected by O—H...O hydrogen bonds, resulting in a three‐dimensional (3D) supramolecular structure. In 2, the CdII centres are coordinated by Seb2− ligands to form binuclear Cd2 units which are linked by bbimb and Seb2− ligands into a 2D hxl layer. The 2D layers are further connected by O—H...O hydrogen bonds, leading to an 8‐connected 3D hex supramolecular network. IR and UV–Vis spectroscopy, thermogravimetric analysis and solid‐state photoluminescence analysis were carried out on both MOFs. Luminescence sensing experiments reveal that both MOFs have good selective sensing towards Fe3+ in aqueous solution. [ABSTRACT FROM AUTHOR]