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Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance.

ABSTRACT: Microscale swimming may be intuited to be dominated by background flows, sweeping away any untethered bodies with the prevalent flow direction. However, it has been observed that many microswimmers utilize ambient flows as guidance cues, in some cases resulting in net motion upstream, contrary to the dominant background fluid direction and our accompanying intuition. Thus the hydrodynamic response of small-scale motile organisms requires careful analysis of the complex interaction between swimmer and environment. Here we investigate the effects of a Newtonian shear flow on monoflagellated swimmers with specified body symmetry, representing, for instance, the Leishmania mexicana promastigote, a parasitic hydrodynamic puller that inhabits the microenvironment of a sandfly vector midgut and is the cause of a major and neglected human tropical disease. We observe that a lack of symmetry-breaking cellular geometry results in the periodic tumbling of swimmers in the bulk, with the rotations exhibiting a linear response to changes in shearing rate enabling analytic approximation. In order to draw comparisons with the better-studied pushers, we additionally consider virtual Leishmania promastigotes in a confined but typical geometry, that of a no-slip planar solid boundary, and note that in general stable guided taxis is not exhibited amongst the range of observed behaviors. However, a repulsive boundary gives rise to significant continued taxis in the presence of shearing flow, a phenomenon that may be of particular pertinence to the infective lifecycle stage of such swimmers subject to the assumption of a Newtonian medium. We finally propose a viable and general in vitro method of controlling microswimmer boundary accumulation using temporally evolving background shear flows, based on the analysis of phase-averaged dynamics and verified in silico.

SUBMITTER: Walker BJ

PROVIDER: S-EPMC6333290 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance.

Walker Benjamin J BJ Ishimoto Kenta K Wheeler Richard J RJ Gaffney Eamonn A EA

Physical review. E 20181201 6

Microscale swimming may be intuited to be dominated by background flows, sweeping away any untethered bodies with the prevalent flow direction. However, it has been observed that many microswimmers utilize ambient flows as guidance cues, in some cases resulting in net motion upstream, contrary to the dominant background fluid direction and our accompanying intuition. Thus the hydrodynamic response of small-scale motile organisms requires careful analysis of the complex interaction between swimme ...[more]

PMID: 30656244

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Project description:During the development of the Drosophila central nervous system the process of midline crossing is orchestrated by a number of guidance receptors and ligands. Many key axon guidance molecules have been identified in both invertebrates and vertebrates, but the transcriptional regulation of growth cone guidance remains largely unknown. One open question is whether transcriptional regulation plays a role in midline crossing, or if local translation can account for the necessary fine tuning of protein levels. To investigate this issue, we conducted a genome wide analysis of transcription in Drosophila embryos using wild type and a number of well-characterized Drosophila guidance mutants and transgenics. We also analyzed a publicly available microarray time course of Drosophila embryonic development with an axon guidance focus. Using hopach, a novel clustering method which is well suited to microarray data analysis, we identified groups of genes with similar expression patterns across guidance mutants and transgenics. We then systematically characterized the resulting clusters with respect to their relevance to axon guidance using two complementary controlled vocabularies: the Gene Ontology (GO) and anatomical annotations of the Atlas of Pattern of Gene Expression (APoGE) in situ hybridization database. The analysis indicates that regulation of gene expression does play a role in the process of axon guidance in Drosophila. We also find a strong link between axon guidance and hemocyte migration, a result that agrees with mounting evidence that axon guidance molecules are co-opted in vertebrate vascularization. Cell cyclin activity in the context of axon guidance is also suggested from our array data. RNA and protein patterns of cell cyclin in axon guidance mutants and transgenics support this possible link. This study provides important insights into the regulation of axon guidance in vivo and suggests that transcription does play a role in control of axon guidance. Keywords: Mutant Analysis

Dataset Information

Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance.

Publications

Response of monoflagellate pullers to a shearing flow: A simulation study of microswimmer guidance.

Similar Datasets

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