Typically, ∼0.1% of the total number of olfactory sensory neurons (OSNs) in the main olfactory epithelium express the same odorant receptor (OR) in a singular fashion and their axons coalesce into homotypic glomeruli in the olfactory bulb. Here, we have dramatically increased the total number of OSNs expressing specific cloned OR coding sequences by multimerizing a 21-bp sequence encompassing the predicted homeodomain binding site sequence, TAATGA, known to be essential in OR gene choice. Singular gene choice is maintained in these "MouSensors." In vivo synaptopHluorin imaging of odor-induced responses by known M71 ligands shows functional glomerular activation in an M71 MouSensor. Moreover, a behavioral avoidance task demonstrates that specific odor detection thresholds are significantly decreased in multiple transgenic lines, expressing mouse or human ORs. We have developed a versatile platform to study gene choice and axon identity, to create biosensors with great translational potential, and to finally decode human olfaction.

Highlights d IL-6, IL-10, IL-1ra, CCL2, and CRP rose significantly on landing after a year in space d IL-6 and IL-1ra are potential targets for pharmacological intervention in astronauts d These cytokines are also associated with muscle regeneration in response to gravity d Muscle-generated IL-6 drives classic signaling cascades in an anti-inflammatory role

Zika virus (ZIKV) infection results in an increased risk of spontaneous abortion and poor intrauterine growth although the underlying mechanisms remain undetermined. Little is known about the impact of ZIKV infection during the earliest stages of pregnancy, at pre- and peri-implantation, because most current ZIKV pregnancy studies have focused on post-implantation stages. Here, we demonstrate that trophectoderm cells of pre-implantation human and mouse embryos can be infected with ZIKV, and propagate virus causing neural progenitor cell death. These findings are corroborated by the dose-dependent nature of ZIKV susceptibility of hESC-derived trophectoderm cells. Single blastocyst RNA-seq reveals key transcriptional changes upon ZIKV infection, including nervous system development, prior to commitment to the neural lineage. The pregnancy rate of mice is >50% lower in pre-implantation infection than infection at E4.5, demonstrating that pre-implantation ZIKV infection leads to miscarriage. Cumulatively, these data elucidate a previously unappreciated association of pre- and peri-implantation ZIKV infection and microcephaly.

We performed an extensive mutational analysis of the canonical mouse odorant receptor (OR) M71 to determine the properties of ORs that inhibit plasma membrane trafficking in heterologous expression systems. We employed the use of the M71::GFP fusion protein to directly assess plasma membrane localization and functionality of M71 in heterologous cells in vitro or in olfactory sensory neurons (OSNs) in vivo. OSN expression of M71::GFP show only small differences in activity compared to untagged M71. However, M71::GFP could not traffic to the plasma membrane even in the presence of proposed accessory proteins RTP1S or mβ2AR. To ask if ORs contain an internal “kill sequence”, we mutated ~15 of the most highly conserved OR specific amino acids not found amongst the trafficking non-OR GPCR superfamily; none of these mutants rescued trafficking. Addition of various amino terminal signal sequences or different glycosylation motifs all failed to produce trafficking. The addition of the amino and carboxy terminal domains of mβ2AR or the mutation Y289A in the highly conserved GPCR motif NPxxY does not rescue plasma membrane trafficking. The failure of targeted mutagenesis on rescuing plasma membrane localization in heterologous cells suggests that OR trafficking deficits may not be attributable to conserved collinear motifs, but rather the overall amino acid composition of the OR family. Thus, we performed an in silico analysis comparing the OR and other amine receptor superfamilies. We find that ORs contain fewer charged residues and more hydrophobic residues distributed throughout the protein and a conserved overall amino acid composition. From our analysis, we surmise that it may be difficult to traffic ORs at high levels to the cell surface in vitro, without making significant amino acid modifications. Finally, we observed specific increases in methionine and histidine residues as well as a marked decrease in tryptophan residues, suggesting that these changes provide ORs with special characteristics needed for them to function in olfactory neurons.