Tunable terahertz absorber based on transparent and flexible metamaterial

We demonstrate a tunable terahertz(THz) absorber based on an indium tin oxide(ITO) metamaterial. The upper ITO cross-shaped metasurface with different arm lengths is fabricated by direct femtosecond laser etching.The thickness of the middle dielectric layer is only 60 μm, which makes the absorber very transparent and flexible. The experimental results show that the THz resonant peaks have a high performance near 1 THz. By setting spacers of different thicknesses between the middle layer and the ITO mirror, a new type of tunable THz absorber is proposed. Its absorption peak frequency can be continuously adjusted from 0.92 to 1.04 THz between TE and TM polarization. This transparent THz metamaterial absorber is expected to be widely used in THz imaging, sensing, and biological detection.

Transcriptome analyses of insect cells to facilitate baculovirus-insect expression

The High Five cell line （BTI-TN-5B1-4） isolated from the cabbage looper, Trichoplusia ni is an insect cell line widely used for baculovirus-mediated recombinant protein expression. Despite its widespread application in industry and academic laboratories, the genomic background of this cell line remains unclear. Here we sequenced the transcriptome of High Five cells and assembled 25,234 transcripts. Codon usage analysis showed that High Five cells have a robust codon usage capacity and therefore suit for expressing proteins of both eukaryotic- and prokaryotic-origin. Genes involved in glycosylation were profiled in our study, providing guidance for engineering glycosylated proteins in the insect cells. We also predicted signal peptides for transcripts with high expression abundance in both High Five and Sf21 cell lines, and these results have important implications for optimizing the expression level of some secretory and membrane proteins.

Genome-wide CRISPR activation screen identifies candidate receptors for SARS-CoV-2 entry

The outbreak of coronavirus disease 2019(COVID-19) caused by SARS-CoV-2 has created a global health crisis. SARS-CoV-2 infects varieties of tissues where the known receptor ACE2 is low or almost absent, suggesting the existence of alternative viral entry pathways. Here, we performed a genome-wide barcoded-CRISPRa screen to identify novel host factors that enable SARS-CoV-2 infection. Beyond known host proteins, i.e., ACE2, TMPRSS2, and NRP1, we identified multiple host components,among which LDLRAD3, TMEM30A, and CLEC4G were confirmed as functional receptors for SARS-CoV-2. All these membrane proteins bind directly to spike’s N-terminal domain(NTD). Their essential and physiological roles have been confirmed in either neuron or liver cells. In particular, LDLRAD3 and CLEC4G mediate SARS-CoV-2 entry and infection in an ACE2-independent fashion. The identification of the novel receptors and entry mechanisms could advance our understanding of the multiorgan tropism of SARS-CoV-2, and may shed light on the development of COVID-19 countermeasures.

A non-ACE2-blocking neutralizing antibody against Omicron-included SARS-CoV-2 variants

Dear Editor,The emergence of severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)variants threatens efforts to contain the coronavirus disease 2019(COVID-19)pandemic.Omicron(B.1.1.529),the fifth novel SARS-CoV-2 variant of concern(VOC),harbors 15 mutations in the receptor-binding domain(RBD)of the spike(S)protein.1 These mutations include almost all the sites of existing VOCs(Alpha/B.1.1.7,Beta/B.1.351,Gamma/P.1,and Delta/B.1.617.2).2–4 Importantly,the key mutations directly interact with the ACE2 receptor and constitute the main target of neutralizing antibodies(NAbs),which is believed to alter the sensitivity to a large number of NAbs.

Structure of unliganded membrane-proxima domains FN4-FN5-FN6 of DCC

Dear Editor, Deleted in colorectal cancer （DCC） is a single pass transmembrane glycoprotein that was originally identified in humans as a candidate tumor suppressor （Fearon et al., 1990）. DCC belongs to the immunoglobulin superfamily, and the extracellular fragment is composed of four immunoglobu- lin-like （Ig-like） domains followed by six fibronectin type III （FN） domains. DCC plays a pivotal role in axon guidance by mediating a combination of attractive and repulsive effects through interactions with the diffusible guidance cue,