Cryo-EM structure of human HCN3 channel and its regulation by cAMP.

HCN channels are important for regulating heart rhythm and nerve activity and have been studied as potential drug targets for treating depression, arrhythmia, nerve pain, and epilepsy. Despite possessing unique pharmacological properties, HCN channels share common characteristics in that they are activated by hyperpolarization and modulated by cAMP and other membrane lipids. However, the mechanisms of how these ligands bind and modulate HCN channels are unclear. In this study, we solved structures of full-length human HCN3 using cryo-EM and captured two different states, including a state without any ligand bound and a state with cAMP bound. Our structures reveal the novel binding sites for cholesteryl hemisuccinate in apo state and show how cholesteryl hemisuccinate and cAMP binding cause conformational changes in different states. These findings explain how these small modulators are sensed in mammals at the molecular level. The results of our study could help to design more potent and specific compounds to influence HCN channel activity and offer new therapeutic possibilities for diseases that lack effective treatment.

Enhanced ferroelectric and piezoelectric performance of (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 lead-free ceramics upon Ce and Sb co-doping.

(Ba0.85Ca0.15)(Zr0.1Ti0.9-x Ce x )O3+ySb (abbreviated as BCZTC x S y ) ceramics were prepared by the conventional solid-state reaction. The effect of the co-doping of Ce and Sb on the phase structure, microstructure, dielectric, and ferroelectric and piezoelectric performances of BCZTC x S y ceramics were investigated systematically. The results indicated that the obtained ceramics are composed of coexisting rhombohedral and tetragonal phases. Significant improvements were also observed in the growth of grain, relative density, as well as electrical performance. After co-doping 0.05 mol% Ce and 0.10 mol% Sb, the sizes of crystalline grains reached the maximum. The following optimal properties were obtained: ε r = 2353, tan δ = 0.026, T c = 109.4 °C, P max = 17.65 µC cm-2, P r = 10.43 µC cm-2, E c = 2.88 kV cm-1, S max = 0.125%, = 417 pm V-1, d 33 = 372 pC N-1. With the increase in dopants, the diffuseness γ increased from 1.663 to 1.733, indicating a more relaxed ferroelectric characteristic. All improvements show that BCZT ceramics co-doped with Ce and Sb could be promising candidates in lead-free devices.

Effect of the polarity of KTa1-x Nb x O3 on the dielectric performance of the KTN/PVDF nanocomposites.

KTa1-x Nb x O3 with different Ta/Nb ratios (x = 0.15, 0.25, 0.5, 0.75, 0.85) were engineered and prepared by a facile hydrothermal synthesis method to acquire KTN nanoparticles with varied polarity. To investigate the effect of KTN filler with varied polarity on the dielectric performance of polymer matrix composites, KTN/PVDF films were fabricated. The experiment demonstrated the polarity of KTN affected the dielectric performance of the composites. KTa0.5Nb0.5O3 possesses larger polarity with permittivity of 3780 at 1 kHz due to its Curie temperature is closer to room temperature, which contributes 30 wt% doped KTa0.5Nb0.5O3/PVDF composite achieving higher permittivity of 19.5 at 1 kHz than those of the others. Additionally, KTa0.75Nb0.25O3/PVDF composite presents higher breakdown strength than those of the others with an E b value of 164 kV mm-1 when 20 wt% filler is doped. The significant improved dielectric performance by Ta/Nb ratio engineering has the potential of providing new insight on enhancing the energy storage in ceramic-polymer nanocomposites.

The whole chloroplast genomes of two Eutrema species (Brassicaceae).

In this study, we determined the complete chloroplast genomes from two crucifer species of the Eutrema genus. The sizes of the two cp genomes were 153 948 bp (E. yunnanense) and 153 876 bp (E. heterophyllum). Both genomes have the typical quadripartite structure consisting of a large single copy region, a small single copy region and two inverted repeats. Gene contents and their relative positions of the 132 individual genes (87 protein-coding genes, eight rRNA, and 37 tRNA genes) of either genome were identical to each other. Phylogenetic analysis supports the idea that the currently recognized Eutrema genus is monophyletic and that E. salsugineum and Schrenkiella parvula evolved salt tolerance independently.

The complete chloroplast genome of Ostrya rehderiana.

The complete chloroplast sequence of Ostrya rehderiana is 159 347 bp in length, containing 85 protein-coding genes, 8 ribosomal RNA genes, and 31 transfer RNA genes. The circular genome exhibits a typical chloroplast genome structure comprising a large single copy region of 88 552 bp, a small single copy region of 18 941 bp and a pair of inverted repeats of 25 927 bp. The overall GC content of the chloroplast genome is 36.5%. Phylogenetic analysis of O. rehderiana sequence together with 12 complete chloroplast genomes revealed a basal placement of O. rehderiana within the Fagales species.

The complete chloroplast genome of Schrenkiella parvula (Brassicaceae).

Schrenkiella parvula is an Arabidopsis-related model species used here for studying plant stress tolerance. In this study, the complete chloroplast genome sequence of S. parvula has been reported for the first time. The total length of the chloroplast genome was 153 979 bp, which had a typical quadripartite structure. The annotated plastid genome includes 87 protein-coding genes, 39 tRNA genes and 8 ribosomal RNA genes. The evolutionary relationships revealed by our phylogenetic analysis indicated that S. parvula is closer to the Brassiceae species when compared with Eutrema salsugineum.

Contrasting responses to Pleistocene climate changes: a case study of two sister species Allium cyathophorum and A. spicata (Amaryllidaceae) distributed in the eastern and western Qinghai-Tibet Plateau.

It has been hypothesized that species occurring in the eastern and the western Qinghai-Tibet Plateau (QTP) responded differently to climate changes during the Pleistocene. Here, we test this hypothesis by phylogeographic analysis of two sister species, Allium cyathophorum and A. spicata. We sequenced two chloroplast DNA (cpDNA) fragments (accD-psaI and the rpl16 intron) of 150 individuals, and the nuclear (ITS) region of 114 individuals, from 19 populations throughout the distributional ranges of these species. The divergence between the two species was dated at 779 - 714 thousand years before the present and was likely initiated by the most major glaciation in the QTP. Analysis of chlorotype diversity showed that A. spicata, the species occurring in the western QTP, contains much lower genetic diversity (0.25) than A. cyathophorum (0.93), which is distributed in the eastern QTP. Moreover, multiple independent tests suggested that the A. spicata population had expanded recently, while no such expansion was detected in A. cyathophorum, indicating a contrasting pattern of responses to Pleistocene climate changes. These findings highlight the importance of geographical topography in determining how species responded to the climate changes that took place in the QTP during the Pleistocene.