Early structural and functional changes in Baikal Sculpin gills exposed to suspended soot microparticles in experiment

Degenerative and Regenerative Actin Cytoskeleton Rearrangements, Cell Death, and Paradoxical Proliferation in the Gills of Pearl Gourami (Trichogaster leerii) Exposed to Suspended Soot Microparticles

“…When exposed to soot, the main quantity of TUNEL-positive cells in the gill epithelium concentrates at the edges of gill lamellae and filaments, which appear to be the hydrodynamic force impact (shear stress) zones most susceptible to mechanical stress and turbulent fluid flow, which creates optimal conditions for the adhesion of soot microparticles to the tissue surface. The value of this parameter and the localization of apoptotic cells on day 5 of the soot exposure coincide with the data obtained for P. knerii with a similar exposure [39]. This is evidence for the universal effect of the soot microparticles used in the experiment on the gill epithelium of fish and for the objectivity of the TUNEL method used to assess the cytotoxic effect of soot microparticles.…”

“…It has been shown that actin is one of the main objects of carboxylation and glutathionylation under oxidative stress [74], which leads to its rearrangements, including aggregation and concentration in the perinuclear space [75,76]. The development of oxidative stress in fish gill cells when exposed to soot was shown in a similar experiment in our previous study [39]. This suggests that the formation of actin aggregates in gill epithelial cells after 5 and 14 days of exposure to soot microparticles is a consequence of oxidative stress.…”

“…Continuous death of senescent and damaged cells in combination with the division and subsequent differentiation of stem epithelial cells represents an integral feature of all epithelia [86][87][88]. The intensity of this process was virtually no different from the same parameter in Paracottus knerii, which we estimated previously in [39]. This fact suggests that this level of activity may be typical of most fish.…”

“…We showed that on days 5 and 14, the actin skeletons of mucous cells became deformed, with the loss of the fine structure of the apical region (Figure 2M; Supplementary Video S2), which may be due to hypersecretion. The activation of mucus hypersecretion by gill secretory cells in fish when exposed to soot microparticles was revealed by us previously [39].…”

“…Our previous works were devoted to the effects of short-term (5 days) exposure to soot on Baikalian fishes, evolutionary adapted to the clearest fresh water of Lake Baikal [39]. The data of these experiments provided evidence of a decrease in mitochondrial activity, an increase in reactive oxygen species production, and an increase in the frequency of programmed cell death in the gill epithelium, and macroautophagy in chloride cells of Paracottus knerii (Dybowski, 1874) gills under the influence of soot.…”