| Popis: |
We studied the ultrastructure of Torulopsis sphaerica yeast cells irradiated with He-Ne laser (lambda = 632.8 nm, dose--460 J/m2) and then cultured for 6 h in the nutrient with 1% glucose by aeration. The length of membranes of endoplasmic reticulum (ER) and the number of its associations with mitochondria (M) and plasma membrane (PM) were measured on ultrathin sections. A distance of less than 50 nm between heterogeneous membranes was considered as an "association". The cells from irradiated cultures are characterized by the following features: 1) the length of cortical ER membranes in relation to cellular perimeter, and the length of perinuclear ER membranes in relation to nuclear perimeter increase, resp., by 21 and 79%; 2) the number of ER-PM associations per cellular section, and that per unit of PM length increase, resp., by 26 and 41%; 3) the number of ER-M association in relation to the total mitochondrial perimeter, and to perimitochondrial ER increase by 80 and 87%, resp. The latter may be associated with Ca2+ uptake by mitochondria associated with ER, which results in activation of respiration and ATP production. |
