[Organization of mitochondria in the growing hyphae of Neurospora crassa].

In vivo fluorescent labeling of mitochondria in Neurospora crassa showed the concentration of filamentous mitochondria within 30 µm of apex in growing hyphae. These mitochondrial assemblies propagated forward with the elongation of hyphae, split and segregated as the growing tip bifurcated and formed de novo when new branches formed farther away from the apex. The efficiency of the mitochondria concentration in the apical 30 µm zone is related to the growth rate and identical in hyphae cultivated in glucose- and sorbitol-containing media. The obtained data are discussed in connection with the behavior of microtubules in growing hyphae as well as with the electric heterogeneity of N. crassa hyphal apex described previously.

[Highly permeable contacts and electrical characteristics of the tissue of the normal liver and hepatomas. III. Absence of an effect of the tumor promoter phenobarbital on intercellular contacts in the mouse liver]. / Vysokopronitsaemye kontakty i élektricheskie kharakteristiki tkani normal'noi pecheni gepatom. III. Otsutstvie vliianiia opukholevogo promotora fenobarbitala na mezhkletochnye kontakty v pecheni myshi.

The effect of phenobarbital--a specific promoter of hepatocarcinogenesis--on electrical parameters of mouse liver cells in vitro has been investigated using the conventional microelectrode technique. No alterations were found in cell membrane potentials, input resistances and electrical coupling coefficients measured either immediately after a short-term incubation of isolated livers in the presence of phenobarbital, or after a long-term treatment of the animals per os with the promoter for several weeks.

[3H-colchicine accumulation in a mixed culture of colcemide-resistant and -sensitive cells]. / Nakoplenie 3H-kolkhitsina v smeshannoi kul'ture rezistentnykh i chuvstvitel'nykh k koltsemidu kletok.

Colchicine accumulation was studied in cell monolayer formed by colchicine-sensitive mouse normal fibroblasts and colchicine-resistant cells L-53. Accumulation of 3H-colchicine in the mixed culture of these cells after a 2 hours incubation approached 63% of the total radioactivity in pure cultures of fibroblasts and L-53 cells. Colchicine binding in pure culture of normal fibroblasts somewhat decreased when cell density increased. The results obtained are compatible with the present models of intercellular communication and provide evidence of metabolic cooperation between cells sensitive and resistant to mitostatics.

[Electrical characteristics of normal and transformed fibroblasts in tissue culture]. / Elektricheskie kharakteristiki normal'nykh i transformirovannykh fibroblastov v kulture tkani

The two-electrode method of input resistance measuring was shown to give lower values of resistance compared with the one-electrode balance method. Gradual growth of estimates of input resistance and membrane potential in the cause of experiment is associated with decrease in the shunting effect of the electrode puncture. The mean values of steady Rin of sparse and confluent culture did not differ when the cells were electrically disconnected (38 plus or minus 1.2 MO and 41 plus or minus 1.8 MO respectively) and differed in electrically coupled fibroblasts (54 plus or minus 4.9 MO --sparse; 29 plus or minus 2.2 MO -- confluent culture). This difference is thought to be associated with shunting effect of electrical connections. The specific resistance of membrane was estimated in normal and transformed fibroblasts.

[Highly permeable intercellular junctions in normal and transformed fibroblast cultures]. / Vysokopronitsaemye mezhkletochnye kontakty v kul'turakh normal'nykh itransformirovannykh fibroblastov

Intercellular junctions permeable to ions and fluorescein Na were studied with the aid of intracellular microelectrodes in the cultures of normal and transformed mouse-embryo and hamster-embryo fibroblast-like cells. Normal cells were effectively coupled by the highly permeable junctions. In cultures of 7 types of transformed cells, 3 types of coupling were detected: effective, decreased, and fully reduced couplings. The degree of uncoupling was not correlated with morphological patterns of malignization and tumorogeneity of transformed cultures. The decrease of permeability of intercellular junctions to ions and small molecules is concluded not to be necessary for malignization.