Browsing by Author "Blawzdziewicz, Jerzy (TTU)"
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Item Locomotion of C. elegans: A piecewise-harmonic curvature representation of nematode behavior(2012) Padmanabhan, Venkat (TTU); Khan, Zeina S. (TTU); Solomon, Deepak E. (TTU); Armstrong, Andrew (TTUHSC); Rumbaugh, Kendra P. (TTUHSC); Vanapalli, Siva A. (TTU); Blawzdziewicz, Jerzy (TTU)Caenorhabditis elegans, a free-living soil nematode, displays a rich variety of body shapes and trajectories during its undulatory locomotion in complex environments. Here we show that the individual body postures and entire trails of C. elegans have a simple analytical description in curvature representation. Our model is based on the assumption that the curvature wave is generated in the head segment of the worm body and propagates backwards. We have found that a simple harmonic function for the curvature can capture multiple worm shapes during the undulatory movement. The worm body trajectories can be well represented in terms of piecewise sinusoidal curvature with abrupt changes in amplitude, wavevector, and phase. © 2012 Padmanabhan et al.Item A Markov chain Monte Carlo model of mechanical-feedback-driven progressive apical constrictions captures the fluctuating collective cell dynamics in the Drosophila embryo(2022) Gao, Guo–Jie J; Holcomb, Michael C; Thomas, Jeffrey H (TTUHSC); Blawzdziewicz, Jerzy (TTU)Communication via mechanical stress feedback is believed to play an important role in the intercellular coordination of collective cellular movements. One such movement is ventral furrow formation (VFF) in the Drosophila melanogaster embryo. We previously introduced an active granular fluid (AGF) model, which demonstrated that cellular constriction chains observed during the initial phase of VFF are likely the result of intercellular coordination by tensile-stress feedback. Further observation of individual cellular dynamics motivated us to introduce progressive constrictions and Markov chain Monte Carlo based fluctuation of particle radii to our AGF model. We use a novel stress-based Voronoi tessellation method to translate the anisotropic network of highly polydisperse, axisymmetric force centers into a confluent cellular layer. This allows us to apply a similar means of analysis to both live and simulated embryos. We find that our enhanced AGF model, which combines tensile mechanical stress feedback and individual cellular fluctuations, successfully captures collective cell dynamics.Item Mechanical feedback and robustness of apical constrictions in Drosophila embryo ventral furrow formation(2021) Holcomb, Michael C. (TTU); Gao, Guo-Jie Jason; Servati, Mahsa (TTU); Schneider, Dylan (TTU); McNeely, Presley K.; Thomas, Jeffrey H. (TTUHSC); Blawzdziewicz, Jerzy (TTU)Formation of the ventral furrow in the Drosophila embryo relies on the apical constriction of cells in the ventral region to produce bending forces that drive tissue invagination. In our recent paper we observed that apical constrictions during the initial phase of ventral furrow formation produce elongated patterns of cellular constriction chains prior to invagination and argued that these are indicative of tensile stress feedback. Here, we quantitatively analyze the constriction patterns preceding ventral furrow formation and find that they are consistent with the predictions of our active-granular-fluid model of a monolayer of mechanically coupled stress-sensitive constricting particles. Our model shows that tensile feedback causes constriction chains to develop along underlying precursor tensile stress chains that gradually strengthen with subsequent cellular constrictions. As seen in both our model and available optogenetic experiments, this mechanism allows constriction chains to penetrate or circumvent zones of reduced cell contractility, thus increasing the robustness of ventral furrow formation to spatial variation of cell contractility by rescuing cellular constrictions in the disrupted regions.Item Microfluidics-integrated spaceflight hardware for measuring muscle strength of Caenorhabditis elegans on the International Space Station(2022) Soni, Purushottam (TTU); Anupom, Taslim (TTU); Lesanpezeshki, Leila (TTU); Rahman, Mizanur (TTU); Hewitt, Jennifer E (TTU); Vellone, Matthew; Stodieck, Louis; Blawzdziewicz, Jerzy (TTU); Vanapalli, Siva A (TTU)Caenorhabditis elegans is a low-cost genetic model that has been flown to the International Space Station to investigate the influence of microgravity on changes in the expression of genes involved in muscle maintenance. These studies showed that genes that encode muscle attachment complexes have decreased expression under microgravity. However, it remains to be answered whether the decreased expression leads to concomitant changes in animal muscle strength, specifically across multiple generations. We recently reported the NemaFlex microfluidic device for the measurement of muscle strength of C. elegans (Rahman et al., Lab Chip, 2018). In this study, we redesign our original NemaFlex device and integrate it with flow control hardware for spaceflight investigations considering mixed animal culture, constraints on astronaut time, crew safety, and on-orbit operations. The technical advances we have made include (i) a microfluidic device design that allows animals of a given size to be sorted from unsynchronized cultures and housed in individual chambers, (ii) a fluid handling protocol for injecting the suspension of animals into the microfluidic device that prevents channel clogging, introduction of bubbles, and crowding of animals in the chambers, and (iii) a custom-built worm-loading apparatus interfaced with the microfluidic device that allows easy manipulation of the worm suspension and prevents fluid leakage into the surrounding environment. Collectively, these technical advances enabled the development of new microfluidics-integrated hardware for spaceflight studies in C. elegans. Finally, we report Earth-based validation studies to test this new hardware, which has led to it being flown to the International Space Station.Item NemaLife chip: a micropillar-based microfluidic culture device optimized for aging studies in crawling C. elegans(2020) Rahman, Mizanur (TTU); Edwards, Hunter (TTU); Birze, Nikolajs (TTU); Gabrilska, Rebecca (TTUHSC); Rumbaugh, Kendra P. (TTUHSC); Blawzdziewicz, Jerzy (TTU); Szewczyk, Nathaniel J.; Driscoll, Monica; Vanapalli, Siva A. (TTU)In this study, we report a microfluidic device for the whole-life culture of the nematode Caenorhabditis elegans that allows the scoring of animal survival and health measures. This device referred to as the NemaLife chip features: (1) an optimized micropillar arena in which animals can crawl, (2) sieve channels that separate progeny and prevent the loss of adults from the arena during culture maintenance, and (3) ports that allow rapid accessibility for feeding the adult-only population and introducing reagents as needed. The pillar arena geometry was optimized to accommodate the growing body size during culture and emulate the body gait and locomotion of animals reared on agar. Likewise, feeding protocols were optimized to recapitulate longevity outcomes typical of standard plate growth. Key benefits of the NemaLife Chip include eliminating the need to perform repeated manual transfers of adults during survival assays, negating the need for progeny-blocking chemical interventions, and avoiding the swim-induced stress across lifespan in animals reared in liquid. We also show that the culture of animals in pillar-less microfluidic chambers reduces lifespan and introduces physiological stress by increasing the occurrence of age-related vulval integrity disorder. We validated our pillar-based device with longevity analyses of classical aging mutants (daf-2, age-1, eat-2, and daf-16) and animals subjected to RNAi knockdown of age-related genes (age-1 and daf-16). We also showed that healthspan measures such as pharyngeal pumping and tap-induced stimulated reversals can be scored across the lifespan in the NemaLife chip. Overall, the capacity to generate reliable lifespan and physiological data underscores the potential of the NemaLife chip to accelerate healthspan and lifespan investigations in C. elegans.Item Pluronic gel-based burrowing assay for rapid assessment of neuromuscular health in C. elegans(2019) Lesanpezeshki, Leila (TTU); Hewitt, Jennifer E. (TTU); Laranjeiro, Ricardo; Antebi, Adam; Driscoll, Monica; Szewczyk, Nathaniel J.; Blawzdziewicz, Jerzy (TTU); Lacerda, Carla M.R. (TTU); Vanapalli, Siva A. (TTU)Whole-organism phenotypic assays are central to the assessment of neuromuscular function and health in model organisms such as the nematode C. elegans. In this study, we report a new assay format for engaging C. elegans in burrowing that enables rapid assessment of nematode neuromuscular health. In contrast to agar environments that pose specific drawbacks for characterization of C. elegans burrowing ability, here we use the optically transparent and biocompatible Pluronic F-127 gel that transitions from liquid to gel at room temperature, enabling convenient and safe handling of animals. The burrowing assay methodology involves loading animals at the bottom of well plates, casting a liquid-phase of Pluronic on top that solidifies via a modest temperature upshift, enticing animals to reach the surface via chemotaxis to food, and quantifying the relative success animals have in reaching the chemoattractant. We study the influence of Pluronic concentration, gel height and chemoattractant choice to optimize assay performance. To demonstrate the simplicity of the assay workflow and versatility, we show its novel application in multiple areas including (i) evaluating muscle mutants with defects in dense bodies and/or M-lines (pfn-3, atn-1, uig-1, dyc-1, zyx-1, unc-95 and tln-1), (ii) tuning assay conditions to reveal changes in the mutant gei-8, (iii) sorting of fast burrowers in a genetically-uniform wild-type population for later quantitation of their distinct muscle gene expression, and (iv) testing proteotoxic animal models of Huntington and Parkinson’s disease. Results from our studies show that stimulating animals to navigate in a dense environment that offers mechanical resistance to three-dimensional locomotion challenges the neuromuscular system in a manner distinct from standard crawling and thrashing assays. Our simple and high throughput burrowing assay can provide insight into molecular mechanisms for maintenance of neuromuscular health and facilitate screening for therapeutic targets.Item Spaceflight Induces Strength Decline in Caenorhabditis elegans(2023) Soni, Purushottam (TTU); Edwards, Hunter (TTU); Anupom, Taslim (TTU); Rahman, Mizanur (TTU); Lesanpezeshki, Leila (TTU); Blawzdziewicz, Jerzy (TTU); Cope, Henry; Gharahdaghi, Nima; Scott, Daniel; Toh, Li Shean; Williams, Philip M.; Etheridge, Timothy; Szewczyk, Nathaniel; Willis, Craig R.G.; Vanapalli, Siva A. (TTU)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.Item Streaming Current for Surfaces Covered by Square and Hexagonal Monolayers of Spherical Particles(2023) Blawzdziewicz, Jerzy (TTU); Adamczyk, Zbigniew; Ekiel-Jeżewska, Maria L.The interface and particle contributions to the streaming current of flat substrates covered with ordered square or hexagonal monolayers of spherical particles were theoretically evaluated for particle coverage up to close packing. The exact numerical results were approximated using fitting functions that contain exponential and linear terms to account for hydrodynamic screening and charge convection from the particle surfaces exposed to external flow. According to our calculations, the streaming currents for the ordered and random particle arrangements differ within a typical experimental error. Thus, streaming-current measurements, supplemented with our fitting functions, can be conveniently used to evaluate the particle coverage without detailed knowledge of the particle distribution. Our results for equal interface and particle ζ-potentials indicate that roughness can reduce the streaming current by more than 30%, even in the limit of the small size of spherical roughness asperities.Item The integrin-adhesome is required to maintain muscle structure, mitochondrial ATP production, and movement forces in Caenorhabditis elegans(2015) Etheridge, Timothy; Rahman, Mizanur (TTU); Gaffney, Christopher J.; Shaw, Debra; Shephard, Freya; Magudia, Jignesh; Solomon, Deepak E. (TTU); Milne, Thomas; Blawzdziewicz, Jerzy (TTU); Constantin-Teodosiu, Dumitru; Greenhaff, Paul L.; Vanapalli, Siva A. (TTU); Szewczyk, Nathaniel J.The integrin-adhesome network, which contains >150 proteins, is mechano-transducing and located at discreet positions along the cell-cell and cell-extracellular matrix interface. A small subset of the integrin-adhesome is known to maintain normal muscle morphology. However, the importance of the entire adhesome for muscle structure and function is unknown. We used RNA interference to knock down 113 putative Caenorhabditis elegans homologs constituting most of the mammalian adhesome and 48 proteins known to localize to attachment sites in C. elegans muscle. In both cases, we found >90% of components were required for normal muscle mitochondrial structure and/or proteostasis vs. empty vector controls. Approximately half of these, mainly proteins that physically interact with each other, were also required for normal sarcomere and/or adhesome structure. Next we confirmed that the dystrophy observed in adhesome mutants associates with impaired maximal mitochondrial ATP production (P < 0.01), as well as reduced probability distribution of muscle movement forces compared with wild-type animals. Our results show that the integrin-adhesome network as a whole is required for maintaining both muscle structure and function and extend the current understanding of the full complexities of the functional adhesome in vivo.