Biology subjects

Nashchekin, D.

Publications and source records attributed to Nashchekin, D..

4 recordsLinked to original sources

bioRxiv2024

User-friendly Oblique Plane Microscopy on a fully functional commercially available microscope base

In this work we present an Oblique Plane Microscope designed to work seamlessly with a commercially available microscope base. To support all the functionality offered by the microscope base, where the position of the objective lens is not fixed, we adopted a two-mirror scanning geometry that can compensate for changes to the position of the objective lens during routine microscope operation. We showed that within the expected displacement range of the 100X, 1.35 NA objective lens away from its designed position, and for most practical applications, there is no significant effect on the resolving power, or the fidelity of the 3D data produced by the microscope. Compared to the more traditional scan-lens/galvo-mirror combination, the two-mirror scanning geometry offers higher light-efficiency and a more compact footprint, which could be beneficial to all OPM designs regardless of the use of a commercial base or not.

biophysics↗

bioRxiv2023

The Shot CH1 domain recognises a distinct form of F-actin during Drosophila oocyte determination

As in mammals, only one cell in a Drosophila multicellular female germline cyst is specified as an oocyte. The symmetry-breaking cue for oocyte selection is provided by the fusome, a tubular structure connecting all cells in the cyst. The Drosophila spectraplakin Shot localises to the fusome and translates its asymmetry into a polarised microtubule network that is essential for oocyte specification, but how Shot recognises the fusome is unclear. Here we demonstrate that Shots actin-binding domain (ABD) is necessary and sufficient to localise Shot to the fusome and mediates Shot function in oocyte specification together with the microtubule-binding domains. The calponin homology domain 1 (CH1) of Shots ABD recognises fusomal F-actin and requires CH2 to distinguish it from other forms of F-actin in the cyst. By contrast, the ABDs of Utrophin, Fimbrin, Filamin, Lifeact and F-tractin do not recognise fusomal F-actin. We therefore propose that Shot propagates fusome asymmetry by recognising a specific conformational state of F-actin on the fusome.

cell biology↗

bioRxiv2021

Symmetry breaking in the female germline cyst

In mammals and flies, only a limited number of cells in a multicellular female germline cyst become oocytes, but how the oocyte is selected is unknown. Here we show that the microtubule minus end-stabilizing protein, Patronin/CAMSAP marks the future Drosophila oocyte and is required for oocyte specification. The spectraplakin, Shot, recruits Patronin to the fusome, a branched structure extending into all cyst cells. Patronin stabilizes more microtubules in the cell with most fusome and this weak asymmetry is amplified by Dynein-dependent transport of Patronin-stabilized microtubules. This forms a polarized microtubule network, along which Dynein transports oocyte determinants into the presumptive oocyte. Thus, Patronin amplifies a weak fusome anisotropy to break cyst symmetry. These findings reveal a molecular mechanism of oocyte selection in the germline cyst.

developmental biology↗

bioRxiv2017

Localised Dynactin Protects Growing Microtubules To Deliver Oskar mRNA To The Posterior Cortex Of The Drosophila Oocyte

The localisation of oskar mRNA to the posterior of the Drosophila oocyte defines where the abdomen and germ cells form in the embryo. Kinesin 1 transports oskar mRNA to the oocyte posterior along a polarised microtubule cytoskeleton that grows from non-centrosomal microtubule organising centres (ncMTOCs) along the anterior/lateral cortex. Here we show that the formation of this polarised microtubule network also requires the posterior regulation of microtubule growth. A mutation in the Dynactin Arp1 subunit causes most oskar mRNA to localise in the posterior cytoplasm rather than cortically. oskar mRNA transport and anchoring are normal in this mutant, but the microtubules fail to reach the posterior pole. Thus, Dynactin acts as an anti-catastrophe factor that extends microtubule growth posteriorly. Kinesin 1 transports Dynactin to the oocyte posterior, creating a positive feedback loop that increases the length and persistence of the posterior microtubules that deliver oskar mRNA to the cortex.

cell biology↗