Time-lapse film analysis of cytoplasmic streaming during late oogenesis ofDrosophila

Abstract

Cytoplasmic streaming in follicles of Drosophila has been analysed in vitro by means of time-lapse films. Late vitellogenic follicles develop normally in vitro as judged by morphological criteria. Furthermore, follicles (stage 10 and younger) which were cultured in vitro for the same length of time as follicles which were filmed, developed normally in vivo after injection into a host fly. The recorded cytoplasmic movements are, therefore, unlikely to be an in vitro artefact. At early vitellogenic stages (up to stage 9; King, 1970) no cytoplasmic streaming can be detected, but at stage 10A cytoplasmic movements are initiated within the oocyte. At stage 10B, when the nurse cells start degenerating, nurse cell cytoplasm can be seen to flow into the growing oocyte. At stage 11 a central stream of nurse-cell cytoplasm reaches the oocyte within a minute. The ooplasmic streaming is most rapid at stage 10B and stage 11 and only an oocyte cortex up to 7 μm thick remains stationary. Once the bulk of the nurse-cell cytoplasm has poured into the oocyte (stage 12) the cytoplasmic movement ceases, first in the nurse cells and later in the ooplasm. In mature oocytes no cytoplasmic streaming can be detected.

Colloidal transport by active filaments

“…At the sub-cellular scale, special proteins called molecular motors transport macromolecules super-diffusively along microtubule tracks [1][2][3]. At the cellular scale, molecular motors induce collective motion of the intra-cellular fluid, a phenomenon known as cytoplasmic streaming [4][5][6]. At the extra-cellular scale collective motion of cilia, known as metachronal waves, transports visco-elastic fluids along channels and provides, alongside flagella, motility to whole organisms [7][8][9].…”

Bellymount-Pulsed Tracking: A Novel Approach for Real-Time In vivo Imaging of Drosophila Abdominal Tissues

“…Historically, most studies of Drosophila oogenesis have been performed using fixed samples which necessarily limit the ability to resolve dynamic processes (King, 1970; Spradling, 1993; Diegmiller et al, 2021; Imran Alsous et al, 2021; Weichselberger et al, 2022). However, as early as the 1970s efforts have been made to develop ex-vivo culture protocols for late-stage egg chambers (Petri et al, 1979; Gutzeit and Koppa, 1982). Optimization of late-stage cultures allows survival of stage 10-14 egg chambers for up to 10 hours (Peters and Berg, 2016; Parsons et al, 2023; Zhang and Liu, 2024).…”

Self-organized intracellular twisters

“…During this time, diffusion and directed transport are used to localize several molecular factors needed for the patterning of the future embryo [9,16]. Later, when the oocyte is 150-300 µm long and 100-200 µm wide, large-scale streaming arises, often appearing as a vortex, and having a typical speed of 100-400 nm/s [17][18][19]. This vortex was proposed to be generated by beds of cortically anchored flexible microtubules serving as tracks for plus-end-directed Kinesin-1 motor proteins moving free microtubules and other payloads [18][19][20][21][22][23].…”