Inside Cover: Fiber‐based fluorescence lifetime imaging of recellularization processes on vascular tissue constructs (J. Biophotonics 9/2018)

Tissue autofluorescence provides fluorescence lifetime contrast between acellular tissue and that containing newly seeded cells. Fiber‐based fluorescence lifetime imaging (FLIm) can be used for tracking recellularization of engineered vascular grafts and potential matrix remodeling at large scale, without compromising sample integrity. FLIm cellular contrast was verified in a subset of samples seeded with eGFP‐labelled cells. Results suggests fiberbased FLIm is a suitable tool for monitoring recellularization of engineered tissue nondestructively. Further details can be found in the article by Alba Alfonso‐Garcia, Jeny Shklover, Benjamin E. Sherlock, et al. ( e201700391 ).

     

Informatic search strategies to discover analogues and variants of natural product archetypes

Natural products are a crucial source of antimicrobial agents, but reliance on low-resolution bioactivity-guided approaches has led to diminishing interest in discovery programmes. Here, we demonstrate that two in-house automated informatic platforms can be used to target classes of biologically active natural products, specifically, peptaibols. We demonstrate that mass spectrometry-based informatic approaches can be used to detect natural products with high sensitivity, identifying desired agents present in complex microbial extracts. Using our specialised software packages, we could elaborate specific branches of chemical space, uncovering new variants of trichopolyn and demonstrating a way forward in mining natural products as a valuable source of potential pharmaceutical agents.     

Trophic plasticity among spring vs. cave populations of <Emphasis Type="Italic">Gammarus minus:</Emphasis> examining functional niches using stable isotopes and C/N ratios

In some environments, species may exhibit trophic plasticity, which allows them to extend beyond their assigned functional group. For Gammarus minus, a freshwater amphipod classified as a shredder or detritivore, cave populations have been observed consuming heterotrophs as well as shredding leaves, and therefore may be exhibiting trophic plasticity. To test this possibility, we examined the C and N stable isotope and C/N ratios for cave and spring populations of G. minus. A 15-day feeding experiment using leaves and G. minus from a spring population established that the diet-tissue discrimination factor was 3.2 ‰ for δ¹⁵N. Cave G. minus were 8 ‰ higher in δ¹⁵N relative to cave leaves, indicating they did not derive nitrogen from leaves, whereas field collected spring populations were 2–3 ‰ higher than spring leaves, indicating that they did. Cave G. minus were 2.6 ‰ higher in δ¹⁵N than the cave isopod, Caecidotea holsingeri. Relative to spring populations, Organ Cave G. minus were ¹⁵N enriched by 6 ‰, suggesting they occupied a different trophic level, or incorporated an isotopically distinct N source. While stable isotopes cannot tell what the cave G. minus are eating, the isotopes certainly show that G. minus are not eating leaves and are trophically distinct form the surface populations. Differences in C/N ratios were observed, but reflect the size of the G. minus examined and not feeding group or habitat. The isotope data strongly support the hypothesis that cave populations of G. minus have become generalist or omnivorous by including animal protein in their diet.     

Genomic Modifiers of Natural Killer Cells,Immune Responsiveness and Lymphoid Tissue Remodeling Together Increase Host Resistance to Viral Infection

The MHC class I D^k molecule supplies vital host resistance during murine cytomegalovirus (MCMV) infection. Natural killer (NK) cells expressing the Ly49G2 inhibitory receptor, which specifically binds D^k, are required to control viral spread. The extent of D^k-dependent host resistance, however, differs significantly amongst related strains of mice, C57L and MA/My. As a result, we predicted that relatively small-effect modifier genetic loci might together shape immune cell features, NK cell reactivity, and the host immune response to MCMV. A robust D^k-dependent genetic effect, however, has so far hindered attempts to identify additional host resistance factors. Thus, we applied genomic mapping strategies and multicolor flow cytometric analysis of immune cells in naive and virus-infected hosts to identify genetic modifiers of the host immune response to MCMV. We discovered and validated many quantitative trait loci (QTL); these were mapped to at least 19 positions on 16 chromosomes. Intriguingly, one newly discovered non-MHC locus (Cmv5) controlled splenic NK cell accrual, secondary lymphoid organ structure, and lymphoid follicle development during MCMV infection. We infer that Cmv5 aids host resistance to MCMV infection by expanding NK cells needed to preserve and protect essential tissue structural elements, to enhance lymphoid remodeling and to increase viral clearance in spleen.     

Impact of cell culture on recombinant monoclonal antibody product heterogeneity

Recombinant monoclonal antibodies are commonly expressed in mammalian cell culture and purified by several steps of filtration and chromatography. The resulting high purity bulk drug substance still contains product variants differing in properties such as charge and size. Posttranslational modifications and degradations occurring during cell culture are the major sources of heterogeneity in bulk drug substance of recombinant monoclonal antibodies. The focus of the current review is the impact of cell culture conditions on the types and levels of various modifications and degradations of recombinant monoclonal antibodies. Understanding the relationship between cell culture and product variants can help to make consistently safe and efficacious products. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1103–1112, 2016