N‑Linked Glycosylation Is Required for Transferrin-Induced Stabilization of Transferrin Receptor 2, but Not for Transferrin Binding or Trafficking to the Cell Surface

Transferrin receptor 2 (TfR2) is a member of the transferrin receptor-like family of proteins. Mutations in TfR2 can lead to a rare form of the iron overload disease, hereditary hemochromatosis. TfR2 is proposed to sense body iron levels and increase the level of expression of the iron regulatory hormone, hepcidin. Human TfR2 (hTfR2) contains four potential Asn-linked (N-linked) glycosylation sites on its ectodomain. The importance of glycosylation in TfR2 function has not been elucidated. In this study, by employing site-directed mutagenesis to remove glycosylation sites of hTfR2 individually or in combination, we found that hTfR2 was glycosylated at Asn 240, 339, and 754, while the consensus sequence for N-linked glycosylation at Asn 540 was not utilized. Cell surface protein biotinylation and biotin-labeled Tf indicated that in the absence of N-linked oligosaccharides, hTfR2 still moved to the plasma membrane and bound its ligand, holo-Tf. However, without N-linked glycosylation, hTfR2 did not form the intersubunit disulfide bonds as efficiently as the wild type (WT). Moreover, the unglycosylated form of hTfR2 could not be stabilized by holo-Tf. We further provide evidence that the unglycosylated hTfR2 behaved in manner different from that of the WT in response to holo-Tf treatment. Thus, the putative iron-sensing function of TfR2 could not be achieved in the absence of N-linked oligosaccharides. On the basis of our analyses, we conclude that unlike TfR1, N-linked glycosylation is dispensable for the cell surface expression and holo-Tf binding, but it is required for efficient intersubunit disulfide bond formation and holo-Tf-induced stabilization of TfR2

Data_Sheet_1_Cognitive diagnostic assessment of EFL learners’ listening barriers through incorrect responses.PDF

English as Foreign Language (EFL) learners’ cognitive processes have been a research focus in listening assessment. Most studies use correct responses as data, but undervalue the rich information of the incorrect answers or options (in the case of multiple choice questions, MCQ). However, the MCQ distractors are often intentionally designed to reveal learners’ problems or barriers. In order to diagnose the EFL learners’ listening barriers through incorrect responses, Cognitive Diagnostic Models (CDMs) for bugs were adopted, hence the name Bug-CDMs. First, five EFL listening barrier attributes were identified and two Bug Q-matrices were developed to comparatively analyze the learner’s responses with different Bug-CDMs. The results revealed that Bug-GDINA was the optimal model, and the most prevalent barriers were semantic understanding and vocabulary recognition. These barriers confirmed both compensatory and non-compensatory relationships in causing listening comprehension failures. The study proved the feasibility of Bug-GDINA in diagnosing listening barriers from the incorrect responses. Limitations and suggestions for further research were also proposed.</p

Regio- and Chemoselective Mono- and Bisnitration of 8‑Amino quinoline Amides with Fe(NO₃)₃·9H₂O as Promoter and Nitro Source

An efficient and regioselective remote C(5)–H nitration of 8-aminoquinoline amides by using the economical and nontoxic Fe­(NO₃)₃·9H₂O as promoter and nitro source has been developed. Furthermore, when CuCl₂·2H₂O was used as a catalyst, 8-aminoquinoline amides dominantly underwent bisnitration to give 5,7-dinitro-8-aminoquinoline amides. Notably, this is the first example in which Fe­(NO₃)₃·9H₂O plays a dual role as both chelating promoter and nitration reagent, and CuCl₂·2H₂O acts as an efficient catalyst for the bisnitration of quinolines

Hybrid Nano-Phase Ion/Electron Dual Pathways of Nickel/Cobalt–Boride Cathodes Boosting Intercalation Kinetics for Alkaline Batteries

Nickel-based hydroxides and their derivatives exhibit relatively low capacities and unsatisfactory durability as cathode materials for rechargeable alkaline batteries. In this work, a hybrid NiCo–B nanosheet cathode, integrating electrolyte ion-shuttling channels and electron-transferring networks into a metal–organic framework (MOF), was devised delicately. In the structure, the hybrid ion/electron dual pathways were constructed by NiCo-MOF frameworks and NiCo–B interpenetration networks. It revealed that nano-phase electron-transferring pathways in the MOF obviously boosted ion intercalation kinetics. The as-obtained hybrid NiCo–B nanosheets as cathode materials exhibited reversible capacity as high as 280 mA h g–1 at a current density of 1 A g–1 and excellent rate capability with a capacity retention of 78% from 1 to 10 A g–1. After 2000 charge/discharge cycles at 4 A g–1, the capacity still remained at 94% of the initial one. A full battery assembled with a hybrid NiCo–B cathode and a Fe2O3 anode showed a high capacity of 250 mA h g–1 and a considerable stability of 89% after 1000 cycles. Ragone plots indicated the highest energy density of 409 W h kg–1 and the lowest power density of 1.5 kW kg–1, outperforming other aqueous batteries. It revealed that a syngenetic structure of ion/electron hybrid dual pathways integrated into an MOF could be a potential strategy to optimize ion intercalation electrode materials for alkaline batteries