Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry

We investigate the dynamics of pairs of drops in microfluidic ladder networks with slanted bypasses, which break the fore-aft structural symmetry. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative drop spacing, enabling them to contract, synchronize, expand, or even flip at the ladder exit. Our experiments confirm all these behaviors predicted by theory. Numerical analysis further shows that while ladder networks containing several identical bypasses are limited to nearly linear transformation of input delay between drops, mixed combination of bypasses can cause significant non-linear transformation enabling coding and decoding of input delays.Comment: 4 pages, 5 figure

Mitochondrial sulfide promotes life span and health span through distinct mechanisms in developing versus adult treated Caenorhabditis elegans

This is the final version. Available on open access from the National Academy of Sciences via the DOI in this recordData, Materials, and Software Availability: All study data are included in the article and/or supporting information. The raw RNA sequencing data can be found within the NCBI BioProject database (https://www.ncbi.nlm.nih.gov/bioproject/) under the Sequence Read Archive (SRA) accession PRJNA996496 (93).Living longer without simultaneously extending years spent in good health ("health span") is an increasing societal burden, demanding new therapeutic strategies. Hydrogen sulfide (H2S) can correct disease-related mitochondrial metabolic deficiencies, and supraphysiological H2S concentrations can pro health span. However, the efficacy and mechanisms of mitochondrion-targeted sulfide delivery molecules (mtH2S) administered across the adult life course are unknown. Using a Caenorhabditis elegans aging model, we compared untargeted H2S (NaGYY4137, 100 µM and 100 nM) and mtH2S (AP39, 100 nM) donor effects on life span, neuromuscular health span, and mitochondrial integrity. H2S donors were administered from birth or in young/middle-aged animals (day 0, 2, or 4 postadulthood). RNAi pharmacogenetic interventions and transcriptomics/network analysis explored molecular events governing mtH2S donor-mediated health span. Developmentally administered mtH2S (100 nM) improved life/health span vs. equivalent untargeted H2S doses. mtH2S preserved aging mitochondrial structure, content (citrate synthase activity) and neuromuscular strength. Knockdown of H2S metabolism enzymes and FoxO/daf-16 prevented the positive health span effects of mtH2S, whereas DCAF11/wdr-23 - Nrf2/skn-1 oxidative stress protection pathways were dispensable. Health span, but not life span, increased with all adult-onset mtH2S treatments. Adult mtH2S treatment also rejuvenated aging transcriptomes by minimizing expression declines of mitochondria and cytoskeletal components, and peroxisome metabolism hub components, under mechanistic control by the elt-6/elt-3 transcription factor circuit. H2S health span extension likely acts at the mitochondrial level, the mechanisms of which dissociate from life span across adult vs. developmental treatment timings. The small mtH2S doses required for health span extension, combined with efficacy in adult animals, suggest mtH2S is a potential healthy aging therapeutic.US Army Research OfficeUnited Mitochondrial Disease FoundationUniversity of ExeterUK Space AgencyBiotechnology and Biological Sciences Research Council (BBSRC)NASAOsteopathic Heritage Foundatio

Spaceflight Induces Strength Decline in Caenorhabditis elegans

This is the final version. Available on open access from MDPI via the DOI in this recordData Availability Statement: Raw RNA sequencing data are deposited in the NCBI Sequence Read Archive with links to BioProject ID PRJNA1026503 (https://www.ncbi.nlm.nih.gov/bioproject/).Background: Understanding and countering the well-established negative health consequences of spaceflight remains a primary challenge preventing safe deep space exploration. Targeted/personalized therapeutics are at the forefront of space medicine strategies, and cross-species molecular signatures now define the 'typical' spaceflight response. However, a lack of direct genotype-phenotype associations currently limits the robustness and, therefore, the therapeutic utility of putative mechanisms underpinning pathological changes in flight. Methods: We employed the worm Caenorhabditis elegans as a validated model of space biology, combined with 'NemaFlex-S' microfluidic devices for assessing animal strength production as one of the most reproducible physiological responses to spaceflight. Wild-type and dys-1 (BZ33) strains (a Duchenne muscular dystrophy (DMD) model for comparing predisposed muscle weak animals) were cultured on the International Space Station in chemically defined media before loading second-generation gravid adults into NemaFlex-S devices to assess individual animal strength. These same cultures were then frozen on orbit before returning to Earth for next-generation sequencing transcriptomic analysis. Results: Neuromuscular strength was lower in flight versus ground controls (16.6% decline, p < 0.05), with dys-1 significantly more (23% less strength, p < 0.01) affected than wild types. The transcriptional gene ontology signatures characterizing both strains of weaker animals in flight strongly corroborate previous results across species, enriched for upregulated stress response pathways and downregulated mitochondrial and cytoskeletal processes. Functional gene cluster analysis extended this to implicate decreased neuronal function, including abnormal calcium handling and acetylcholine signaling, in space-induced strength declines under the predicted control of UNC-89 and DAF-19 transcription factors. Finally, gene modules specifically altered in dys-1 animals in flight again cluster to neuronal/neuromuscular pathways, suggesting strength loss in DMD comprises a strong neuronal component that predisposes these animals to exacerbated strength loss in space. Conclusions: Highly reproducible gene signatures are strongly associated with space-induced neuromuscular strength loss across species and neuronal changes in calcium/acetylcholine signaling require further study. These results promote targeted medical efforts towards and provide an in vivo model for safely sending animals and people into deep space in the near future.NASABiotechnology and Biological Sciences Research Council (BBSRC)Engineering and Physical Sciences Research Council (EPSRC)Osteopathic Heritage Foundatio

Mitochondrial hydrogen sulfide supplementation improves health in the C. elegans Duchenne muscular dystrophy model

This is the final version. Available on open access from the National Academy of Sciences via the DOI in this record. Data Availability: All study data are included in the article.Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder characterized by progressive muscle degeneration and weakness due to mutations in the dystrophin gene. The symptoms of DMD share similarities with those of accelerated aging. Recently, hydrogen sulfide (H2S) supplementation has been suggested to modulate the effects of age-related decline in muscle function, and metabolic H2S deficiencies have been implicated in affecting muscle mass in conditions such as phenylketonuria. We therefore evaluated the use of sodium GYY4137 (NaGYY), a H2S-releasing molecule, as a possible approach for DMD treatment. Using the dys-1(eg33) Caenorhabditis elegans DMD model, we found that NaGYY treatment (100 µM) improved movement, strength, gait, and muscle mitochondrial structure, similar to the gold-standard therapeutic treatment, prednisone (370 µM). The health improvements of either treatment required the action of the kinase JNK-1, the transcription factor SKN-1, and the NAD-dependent deacetylase SIR-2.1. The transcription factor DAF-16 was required for the health benefits of NaGYY treatment, but not prednisone treatment. AP39 (100 pM), a mitochondria-targeted H2S compound, also improved movement and strength in the dys-1(eg33) model, further implying that these improvements are mitochondria-based. Additionally, we found a decline in total sulfide and H2S-producing enzymes in dystrophin/utrophin knockout mice. Overall, our results suggest that H2S deficit may contribute to DMD pathology, and rectifying/overcoming the deficit with H2S delivery compounds has potential as a therapeutic approach to DMD treatment.Medical Research Council (MRC)NASABiotechnology and Biological Sciences Research Council (BBSRC)Medical Research Council (MRC)United Mitochondrial Disease FoundationMRC Versus Arthritis Centre for Musculoskeletal Ageing ResearchNational Health and Medical Research CouncilUniversity of Nottingham School of MedicineFulbright U.S. Student ProgramGermanistic Society of AmericaBrian Ridge ScholarshipUniversity of ExeterUniversity of New South WalesUniversity of MelbourneRebecca L. Cooper Medical Research FoundationOsteopathic Heritage Foundatio

Inertio-elastic focusing of bioparticles in microchannels at high throughput

Controlled manipulation of particles from very large volumes of fluid at high throughput is critical for many biomedical, environmental and industrial applications. One promising approach is to use microfluidic technologies that rely on fluid inertia or elasticity to drive lateral migration of particles to stable equilibrium positions in a microchannel. Here, we report on a hydrodynamic approach that enables deterministic focusing of beads, mammalian cells and anisotropic hydrogel particles in a microchannel at extremely high flow rates. We show that on addition of micromolar concentrations of hyaluronic acid, the resulting fluid viscoelasticity can be used to control the focal position of particles at Reynolds numbers up to Re≈10,000 with corresponding flow rates and particle velocities up to 50 ml min[superscript −1] and 130 m s[superscript −1]. This study explores a previously unattained regime of inertio-elastic fluid flow and demonstrates bioparticle focusing at flow rates that are the highest yet achieved.National Institute for Biomedical Imaging and Bioengineering (U.S.) (P41 BioMicroElectroMechanical Systems Resource Center)National Institute for Biomedical Imaging and Bioengineering (U.S.) (P41 EB002503)National Science Foundation (U.S.). Graduate Research FellowshipUnited States. Army Research Office (Institute for Collaborative Biotechnologies Grant W911NF-09-0001

Fluidic Assembly

Fluid-assisted assembly refers to a number of processes that utilize a fluid medium or fluidic forces to assemble components. Fluid-assisted assembly processes often use a fluidic medium to overcome the challenges with grasping and releasing microscale components using traditional methods. These processes can utilize capillary, viscous, magnetic, electrical, and gravitational forces. This category encompasses both stochastic self-assembly processes and directed processes