Experimental Realization of a Skyrmion Circulator

Magnetic skyrmions are mobile topological spin textures that can be manipulated by different means. Their applications have been frequently discussed in the context of information carriers for racetrack memory devices, which on the other hand, exhibit a skyrmion Hall effect as a result of the nontrivial real-space topology. While the skyrmion Hall effect is believed to be detrimental for constructing racetrack devices, we show here that it can be implemented for realizing a three-terminal skyrmion circulator. In analogy to the microwave circulator, nonreciprocal transportation and circulation of skyrmions are studied both numerically and experimentally. In particular, successful control of the circulating direction of being either clockwise or counterclockwise is demonstrated, simply by changing the sign of the topological charge. Our studies suggest that the topological property of skyrmions can be incorporated for enabling novel spintronic functionalities; the skyrmion circulator is just one example

Frequency distribution of single nucleotide polymorphisms identified in <i>Patinopectin yessoensis</i> transcriptomes from different shell color lines.

<p>Frequency distribution of single nucleotide polymorphisms identified in <i>Patinopectin yessoensis</i> transcriptomes from different shell color lines.</p

Comparisons of transcriptional profiles across samples.

<p>(a) Hierarchical clustering of transcripts and samples. (b) The hierarchically clustered Spearman correlation matrix resulting from comparing the transcript expression values for each pair of samples.</p

Interrogation of MDM2 Phosphorylation in p53 Activation Using Native Chemical Ligation: The Functional Role of Ser17 Phosphorylation in MDM2 Reexamined

The E3 ubiquitin ligase MDM2 functions as a crucial negative regulator of the p53 tumor suppressor protein by antagonizing p53 transactivation activity and targeting p53 for degradation. Cellular stress activates p53 by alleviating MDM2-mediated functional inhibition, even though the molecular mechanisms of stress-induced p53 activation still remain poorly understood. Two opposing models have been proposed to describe the functional and structural role in p53 activation of Ser17 phosphorylation in the N-terminal “lid” (residues 1–24) of MDM2. Using the native chemical ligation technique, we synthesized the p53-binding domain (1–109)­MDM2 and its Ser17-phosphorylated analogue (1–109)­MDM2 pS17 as well as (1–109)­MDM2 S17D and (25–109)­MDM2, and comparatively characterized their interactions with a panel of p53-derived peptide ligands using surface plasmon resonance, fluorescence polarization, and NMR and CD spectroscopic techniques. We found that the lid is partially structured in apo-MDM2 and occludes p53 peptide binding in a ligand size-dependent manner. Binding of (1–109)­MDM2 by the (15–29)­p53 peptide fully displaces the lid and renders it completely disordered in the peptide–protein complex. Importantly, neither Ser17 phosphorylation nor the phospho-mimetic mutation S17D has any functional impact on p53 peptide binding to MDM2. Although Ser17 phosphorylation or its mutation to Asp contributes marginally to the stability of the lid conformation in apo-MDM2, neither modification stabilizes apo-MDM2 globally or the displaced lid locally. Our findings demonstrate that Ser17 phosphorylation is functionally neutral with respect to p53 binding, suggesting that MDM2 phosphorylation at a single site is unlikely to play a dominant role in stress-induced p53 activation

Categories classified by Kyoto Encyclopedia of Genes and Genomes (KEGG).

<p>Categories classified by Kyoto Encyclopedia of Genes and Genomes (KEGG).</p

Venn diagram of the expressed genes along the four different <i>Patinopectin yessoensis</i> transcriptomes.

<p>A total of 54,820 genes were co-expressed among the four samples. The Venn diagram serves as an interactive tool for comparing the list, which was plotted using Venn.</p

EuKaryotic Orthologous Groups (KOG) function classifications of <i>Patinopectin yessoensis</i>.

<p>EuKaryotic Orthologous Groups (KOG) function classifications of <i>Patinopectin yessoensis</i>.</p

Gene Ontology classifications of assembled sequences in <i>Patinopectin yessoensis</i> transcriptome.

<p>Gene Ontology classifications of assembled sequences in <i>Patinopectin yessoensis</i> transcriptome.</p

Amounts of trace elements measured in Patinopectin yessoensis (mg/kg).

<p>Amounts of trace elements measured in Patinopectin yessoensis (mg/kg).</p

Quantitative reverse-transcription-PCR validation of differentially expressed gene (DEG) results.

<p>(a) Fold changes measured by mRNA-Seq and real-time RT-PCR. (b) Correlation between the expression fold change level of DEG between P3 and P4.</p