biostudies-literatureWang ZMedical Research CouncilRoyal Society of BiologyWellcome Trustjcs246637https://www.ebi.ac.uk/biostudies/studies/S-EPMC7595685biostudies-literatureUnknown133(20)Eukaryotic flagella undertake different beat types as necessary for different functions; for example, the <i>Leishmania</i> parasite flagellum undergoes a symmetric tip-to-base beat for forward swimming and an asymmetric base-to-tip beat to rotate the cell. In multi-ciliated tissues or organisms, the asymmetric beats are coordinated, leading to movement of the cell, organism or surrounding fluid. This coordination involves a polarisation of power stroke direction. Here, we asked whether the asymmetric beat of the single <i>Leishmania</i> flagellum also has a fixed polarisation. We developed high frame rate dual-colour fluorescence microscopy to visualise flagellar-associated structures in live swimming cells. This showed that the asymmetric <i>Leishmania</i> beat is polarised, with power sJournal of cell scienceThe single flagellum of <i>Leishmania</i> has a fixed polarisation of its asymmetric beat.PMC7595685211075/Z/18/ZUF160661104627/Z/14/Z15/16_MSD_8363381643029UF100435 andBeneke TGluenz EWang ZWheeler RJfalseThe single flagellum of <i>Leishmania</i> has a fixed polarisation of its asymmetric beat.Eukaryotic flagella undertake different beat types as necessary for different functions; for example, the <i>Leishmania</i> parasite flagellum undergoes a symmetric tip-to-base beat for forward swimming and an asymmetric base-to-tip beat to rotate the cell. In multi-ciliated tissues or organisms, the asymmetric beats are coordinated, leading to movement of the cell, organism or surrounding fluid. This coordination involves a polarisation of power stroke direction. Here, we asked whether the asymmetric beat of the single <i>Leishmania</i> flagellum also has a fixed polarisation. We developed high frame rate dual-colour fluorescence microscopy to visualise flagellar-associated structures in live swimming cells. This showed that the asymmetric <i>Leishmania</i> beat is polarised, with power s2020-01-01T00:00:00Z2020 Oct2025-04-22T16:49:57.99Z2020-11-08T09:46:28ZS-EPMC75956853309323010.1242/jcs.246637