Investigation of some antimicrobial procedures on the in vitro development of early murine embryos aimed toward developing methods for the disinfection of mammalian embryos prior to transfer

Eight-cell, zona pellucida-intact mouse embryos were exposed to the following substances or procedures that have been reported to have germicidal effects to determine if the embryos would survive and develop under in vitro conditions: the photosensitive substances hematoporphyrin, hematoporphyrin derivative, 8-methoxypsoralen, 4,5',8-trimethylpsoralen, and thiopyronine; the enzymes lipase (0.5%), phospholipase C (2 U/ml), chymotrypsin (0.5%), and trypsin (0.5%); pH 5.0; and helium/neon laser light, visible light, ultraviolet A light, and ultraviolet C light. Under the conditions used, embryos were not adversely affected by hematoporphyrin and/or helium/neon laser light; methoxypsoralen and/or ultraviolet A light; lipase; trypsin; pH 5.0 for 20 min; and visible light. Variable results were obtained from hematoporphyrin derivative with laser light. Thiopyronine, trimethylpsoralen in combination with ultraviolet A light, and ultraviolet C light killed embryos, and chymotrypsin and phospholipase C were harmful at 10- and 15-min exposure times, respectively.

Cytostatic and cytotoxic properties of pyronin Y: relation to mitochondrial localization of the dye and its interaction with RNA

Pyronin Y (PY) is an intercalating cationic dye that shows specificity towards RNA. In viable cells this dye also accumulates in mitochondria. The cytostatic and cytotoxic effects of PY on L1210 and Chinese hamster ovary cells were studied in relation to its intracellular localization and compared with the affinity of PY to bind to double-stranded DNA and RNA and its propensity to condense single-stranded DNA and RNA. Antitumor properties of PY were tested on L1210 leukemia and Sarcoma 180 ascites in mice. At a concentration of 1.7 to 3.3 microM, PY was localized almost exclusively in mitochondria of cultured cells, similar to another mitochondrial probe, rhodamine 123. At that concentration PY was not toxic but suppressed cell growth, arresting cells in G1. At a concentration of 6.7 to 33.0 microM, PY was also localized in nucleoli and uniformly in cytoplasm, bound to the RNase-sensitive material therein. At that high concentration PY induced cell arrest in G2 and S and was cytotoxic. The dye exhibited a propensity to bind and condense (precipitate) single-stranded nucleic acids, and condensation could be measured by the appearance of light-scattering products. Among a variety of natural and synthetic nucleic acids the most sensitive were the RNA polymer, polyriboadenylate, and the copolymer, polyriboadenylate and polyriboguanylate, which underwent condensation at a PY concentration of 6.6 to 10.0 microM. Natural and synthetic DNA polymers were resistant to condensation. The data suggest that the cytostatic (G2 and S arrest) and cytotoxic (inability to exclude trypan blue, loss of clonogenicity) effects of PY seen at 6.7 to 33.0 microM concentration may be a consequence of the dye binding to RNA. PY may intercalate to double-stranded RNA and/or cause the specific condensation of single-stranded RNA; the polyadenylated sections of mRNA appear to be the most sensitive cellular targets to undergo condensation. PY showed antitumor properties extending survival of L1210 leukemic mice by 50% and slowing growth of Sarcoma 180 ascites tumor. The possibility that certain antitumor drugs, generally believed to act via intercalation to DNA, may exert chemotherapeutic effects via their interactions with RNA is discussed.