Search

Summary: Bacillus thuringiensis (Bt)‐secreted crystal (Cry) toxins form oligomeric pores in host cell membranes and are a common element in generating insect‐resistant transgenic crops. Although Cry toxin function has been well documented, cellular defences against pore‐formation have not been as well developed. Elucidation of the processes underlying this defence, however, could contribute to the development of enhanced Bt crops. Here, we demonstrate that Cry1Ca‐mediated downregulation of microRNA‐7322‐5p (miR‐7322‐5p), which binds to the 3′ untranslated region of p38, negatively regulates the susceptibility of Chilo suppressalis to Cry1Ca. Moreover, Cry1Ca exposure enhanced phosphorylation of Hsp19, and hsp19 downregulation increased susceptibility to Cry1Ca. Further, Hsp19 phosphorylation occurs downstream of p38, and pull‐down assays confirmed the interactions between Hsp19 and Cry1Ca, suggesting that activation of Hsp19 by the miR‐7322‐5p/p38/Hsp19 pathway promotes Cry1Ca sequestration. To assess the efficacy of targeting this pathway in planta, double‐stranded RNA (dsRNA) targeting C. suppressalis p38 (dsp38) was introduced into a previously generated cry1Ca‐expressing rice line (1CH1‐2) to yield a single‐copy cry1Ca/dsp38 rice line (p38‐rice). Feeding on this rice line triggered a significant reduction in C. suppressalis p38 expression and the line was more resistant to C. suppressalis than 1CH1‐2 in both short term (7‐day) and continuous feeding bioassays as well as field trials. These findings provide new insights into invertebrate epithelium cellular defences and demonstrate a potential new pyramiding strategy for Bt crops. [ABSTRACT FROM AUTHOR]

Spintronic devices, especially electric‐field and spin–orbit torque driven magnetic tunnel junctions (MTJs), are promising candidates to replace the current memory and logic components for satisfying future computing demands. Current spin–orbit torque based MTJ devices with a single free layer and spin Hall channel still face high current density for switching. Here, 150‐nm perpendicular MTJs are designed and fabricated with a synthetic‐antiferromagnetic free layer and a bilayered spin Hall channel. The switching behavior is investigated via combination of forces from electric‐field and spin–orbit torque, where the electric field can modulate the exchange coupling of the synthetic‐antiferromagnetic free layer. Through an assistance of spin–orbit torque, bidirectional switching is obtained with switching current density as low as 3 × 103 A cm−2, which is two orders of magnitude lower than that of the current best reported values. These results suggest that electric‐field switching of synthetic‐antiferromagnetic MTJs could be a promising approach for reducing write current density of spintronic devices. [ABSTRACT FROM AUTHOR]

Carbonaceous materials are considered strong candidates as anode materials for sodium‐ion batteries (SIBs), which are expected to play an indispensable role in the carbon‐neutral era. Herein, novel braided porous carbon fibres (BPCFs) are prepared using the chemical vapour deposition (CVD) method. The BPCFs possess interwoven porous structures and abundant vacancies. The growth mechanism of the BPCFs can be attributed to the polycrystalline transformation of the nanoporous copper catalyst in the early stage of CVD process. Density functional theory calculations suggest that the Na+ adsorption energies of the mono‐vacancy edges of the BPCFs (−1.22 and −1.09 eV) are lower than that of an ideal graphene layer (−0.68 eV), clarifying in detail the adsorption‐dominated sodium storage mechanism. Hence, the BPCFs as an anode material present an outstanding discharge capacity of 401 mAh g−1 at 0.1 A g−1 after 500 cycles. Remarkably, this BPCFs anode, under high‐mass‐loading of 5 mg cm−2, shows excellent long‐term cycling ability with a reversible capacity of 201 mAh g−1 at 10 A g−1 over 1000 cycles. This study provided a novel strategy for the development of high‐performance carbonaceous materials for SIBs. [ABSTRACT FROM AUTHOR]

Interlayer exchange coupling in polycrystalline Co2FeAl/Cr/Co2FeAl multilayers with Ta and MgO capping layers is investigated. Compared with Ta‐capped samples, the MgO capping layer induces the oscillatory coupling periods, ≈2.1 nm for Si substrate and ≈4.0 and ≈1.9 nm for SiO2 substrate. The oscillatory coupling period originates from the formation of quantum well states at the Cr/Co2FeAl interface due to the MgO capping layer. Meanwhile, Δ1 Bloch state in the majority spin and Δ2' Bloch state in the minority spin contribute to the short (≈2.1 and ≈1.9 nm) and long oscillatory period (≈4.0 nm) in the disordered B2 Co2FeAl multilayers, respectively. [ABSTRACT FROM AUTHOR]

Keywords: photoreceptors; photobody; cryptochromes; phase separation; NMR EN photoreceptors photobody cryptochromes phase separation NMR 460 462 3 02/23/23 20230301 NES 230301 In plants, cryptochromes (CRYs) are blue light receptors that regulate various developmental progress. (g) Speckles morphology of CRY2 N538-R557-EGFP and CRY2 N538-R557-EGFP+T-NLS in Arabidopsis protoplasts. The introduction of CRY2-EGFP but not EGFP, CRY2 SP PHR sp -EGFP+T-NLS or CRY2 SP D387A sp -EGFP rescued the long hypocotyl phenotype. [Extracted from the article]

Summary: Cellulose is one of the most abundant organic polymers in nature. It contains multiple β‐1,4‐glucan chains synthesized by cellulose synthases (CesAs) on the plasma membrane of higher plants. CesA subunits assemble into a pseudo‐sixfold symmetric cellulose synthase complex (CSC), known as a 'rosette complex'. The structure of CesA remains enigmatic. Here, we report the cryo‐EM structure of the homotrimeric CesA7 from Gossypium hirsutum at 3.5‐angstrom resolution. The GhCesA7 homotrimer shows a C3 symmetrical assembly. Each protomer contains seven transmembrane helices (TMs) which form a channel potentially facilitating the release of newly synthesized glucans. The cytoplasmic glycosyltransferase domain (GT domain) of GhCesA7 protrudes from the membrane, and its catalytic pocket is directed towards the TM pore. The homotrimer GhCesA7 is stabilized by the transmembrane helix 7 (TM7) and the plant‐conserved region (PCR) domains. It represents the building block of CSCs and facilitates microfibril formation. This structure provides insight into how eukaryotic cellulose synthase assembles and provides a mechanistic basis for the improvement of cotton fibre quality in the future. [ABSTRACT FROM AUTHOR]

Summary: The mechanism that coordinates cell growth and cell cycle progression remains poorly understood; in particular, whether the cell cycle and cell wall biosynthesis are coordinated remains unclear. Recently, cell wall biosynthesis and cell cycle progression were reported to respond to wounding. Nonetheless, no genes are reported to synchronize the biosynthesis of the cell wall and the cell cycle. Here, we report that wounding induces the expression of genes associated with cell wall biosynthesis and the cell cycle, and that two genes, AtMYB46 in Arabidopsis thaliana and RrMYB18 in Rosa rugosa, are induced by wounding. We found that AtMYB46 and RrMYB18 promote the biosynthesis of the cell wall by upregulating the expression of cell wall‐associated genes, and that both of them also upregulate the expression of a battery of genes associated with cell cycle progression. Ultimately, this response leads to the development of curled leaves of reduced size. We also found that the coordination of cell wall biosynthesis and cell cycle progression by AtMYB46 and RrMYB18 is evolutionarily conservative in multiple species. In accordance with wounding promoting cell regeneration by regulating the cell cycle, these findings also provide novel insight into the coordination between cell growth and cell cycle progression and a method for producing miniature plants. Significance Statement: How the cell growth and cell cycle progression are coordinated still is one of the remaining great conundrums.Whether there is an interplay between cell cycle and cell wall synthesis is remain unclear. To clarify the relationship between cell growth and cell cycle will be of great significance for rational manipulation of plant growth and shape. Here, we report two wounded‐induced transcription factors, AtMYB46 in Arabidopsis thaliana and RrMYB18 in Rosa rugosa, promote the biosynthesis of the cell wall by up‐regulating the expression of cell wall associated genes, and also up‐regulate the expression of a battery of genes associated with cell cycle progression. Ultimately, this response leads to the change of plant growth and shape. We also found that the coordination of cell wall biosynthesis and cell cycle progression is evolutionarily conservative in multiple species. These findings provide novel insight into the coordination between cell growth and cell cycle progression and a method for producing miniature plants. [ABSTRACT FROM AUTHOR]

MS5 is a meiosis‐related protein belonging to the Brassicaceae‐specific domain of unknown function family and characterized by the MS5 superfamily domain (MSD). In this study, we elucidated the three‐dimensional crystal structure and potential biochemical function of the MSD. It was observed that the MSD adopts a cystatin‐like fold, mainly consisting of a central α‐helix and four‐ or five‐stranded antiparallel β‐sheets that wrap around it. However, unlike cystatins, which inhibit cysteine proteases, the MSD displayed allosteric activation of papain. We believe that our study provides insight into novel mechanisms of proteolytic enzyme regulation and may serve as a basis for functional studies of the MS5 family proteins in plants. [ABSTRACT FROM AUTHOR]

Efficient transcytosis across the blood-brain-barrier is an important strategy for accessing drug targets within the central nervous system. Ligusticum chuanxiong Hort. was used as a messenger drug to increase the distribution of drugs in brain tissue in Traditional Chinese Medicine. The present study investigates the transport of echinacoside (ECH) through MDCK-MDR1 cell and the effects of ligustilide (LIG), senkyunolide A (SENA) and senkyunolide I (SENI) in chuanxiong on its transport. The results indicated that the absorption of ECH was relatively poor in MDCK-MDR1cells, and was concentration dependent and not saturable. The P-glycoprotein inhibitor verapamil could significantly increase the transport of ECH. It indicated that the transport mechanism might be passive diffusion as the dominating process with the active transportation mediated mechanism involved. The increased apparent permeability of ECH in A → B direction by ethylenediaminetetraacetic acid-Na2 suggested that ECH was absorbed via the paracellular route. The transport of ECH in A → B direction significantly increased when co-administrated with increasing concentrations of LIG, SENI and SENA. Western blot analysis and a decrease in transepithelial electrical resistance during the permeation experiment indicated that LIG, SENI and SENA had enhanced the transport of ECH in the BBB models attribute to down-regulate the expressions of claudin-5 and zonula occludens-1 expression. [ABSTRACT FROM AUTHOR]

Ribosomal RNA processing is essential for plastid ribosome biogenesis, but is still poorly understood in higher plants. Here, we show that SUPPRESSOR OF THYLAKOID FORMATION1 ( SOT1), a plastid-localized pentatricopeptide repeat ( PPR) protein with a small MutS-related domain, is required for maturation of the 23S-4.5S rRNA dicistron. Loss of SOT1 function leads to slower chloroplast development, suppression of leaf variegation, and abnormal 23S and 4.5S processing. Predictions based on the PPR motif sequences identified the 5′ end of the 23S-4.5S rRNA dicistronic precursor as a putative SOT1 binding site. This was confirmed by electrophoretic mobility shift assay, and by loss of the abundant small RNA 'footprint' associated with this site in sot1 mutants. We found that more than half of the 23S-4.5S rRNA dicistrons in sot1 mutants contain eroded and/or unprocessed 5′ and 3′ ends, and that the endonucleolytic cleavage product normally released from the 5′ end of the precursor is absent in a sot1 null mutant. We postulate that SOT1 binding protects the 5′ extremity of the 23S-4.5S rRNA dicistron from exonucleolytic attack, and favours formation of the RNA structure that allows endonucleolytic processing of its 5′ and 3′ ends. [ABSTRACT FROM AUTHOR]

Although topological surface states are known to be robust against nonmagnetic surface perturbations, their band dispersions and spatial distributions are still sensitive to surface defects. Taking Bi2Se3 as an example, we demonstrate that Se vacancies modify the surface band structures considerably. When large numbers of Se vacancies exist on the surface, topological surface states may sink down from the first to the second quintuple layer and get separated from the vacancies. We simulated scanning tunnelling microscopy images to distinguish surfaces with Se and Bi terminations. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) Topological surface states are known to be robust against local defects such as vacancies and dangling bonds. In this Letter, another aspect of the topological protection is demonstrated. On the Bi2Se3 surface, topological surface states are found to sink down from the outer surface to the inner atomic layers, separating themselves away from defects, if a large number of Se vacancies exists on the surface. [ABSTRACT FROM AUTHOR]