CD81 T lymphocytes infiltrate the brain during congenital CMV infection and promote viral clearance. However, the mechanisms by which CD81 T cells are recruited to the brain remain unclear. Using a mouse model of congenital CMV, we found a gut-homing chemokine receptor (CCR9) was preferentially expressed in CD81 T cells localized in the brain postinfection. In the absence of CCR9 or CCL25 (CCR9’s ligand) expression, CD81 T cells failed to migrate to key sites of infection in the brain and protect the host from severe forms of disease. Interestingly, we found that expression of CCR9 on CD81 T cells was also responsible for spatial temporal positioning of T cells in the brain. Collectively, our data demonstrate that the CMVinfected brain uses a similar mechanism for CD81 T cell homing as the small intestine.

Two-photon excited fluorescence microscopy is a widely-employed imaging technique that enables the noninvasive study of biological specimens in three dimensions with submicrometer resolution. Here, we report an assessment of a gain-managed nonlinear (GMN) fiber amplifier for multiphoton microscopy. This recently-developed source delivers 58-nJ and 33-fs pulses at 31-MHz repetition rate. We show that the GMN amplifier enables high-quality deep-tissue imaging, and furthermore that the broad spectral bandwidth of the GMN amplifier can be exploited for superior spectral resolution when imaging multiple distinct fluorophores.

Laser speckle contrast imaging (LSCI) is a widefield imaging technique that enables high spatiotemporal resolution measurement of blood flow. Laser coherence, optical aberrations, and static scattering effects restrict LSCI to relative and qualitative measurements. Multi-exposure speckle imaging (MESI) is a quantitative extension of LSCI that accounts for these factors but has been limited to post-acquisition analysis due to long data processing times. Here we propose and test a real-time quasi-analytic solution to fitting MESI data, using both simulated and real-world data from a mouse model of photothrombotic stroke. This rapid estimation of multi-exposure imaging (REMI) enables processing of full-frame MESI images at up to 8 Hz with negligible errors relative to time-intensive least-squares methods. REMI opens the door to real-time, quantitative measures of perfusion change using simple optical systems.

RNA macromolecules, like proteins, fold to assume shapes that are intimately connected to their broadly recognized biological functions; however, because of their high charge and dynamic nature, RNA structures are far more challenging to determine.We introduce an approach that exploits the high brilliance of x-ray free-electron laser sources to reveal the formation and ready identification of angstrom-scale features in structured and unstructured RNAs. Previously unrecognized structural signatures of RNA secondary and tertiary structures are identified through wide-angle solution scattering experiments. With millisecond time resolution, we observe an RNA fold from a dynamically varying single strand through a base-paired intermediate to assume a triplehelix conformation. While the backbone orchestrates the folding, the final structure is locked in by base stacking. This method may help to rapidly characterize and identify structural elements in nucleic acids in both equilibrium and time-resolved experiments.