Dicumyl peroxide (di-CuOOH) and benzoyl peroxide (BzOOH) act as tumor promoters in SENCAR mice, whereas di-tert-butylhydroperoxide does not. Tumor promotion requires the removal of growth suppression by inhibition of gap junctional intercellular communication (GJIC) and the induction of mitogenic intracellular pathways. We showed that di-CuOOH and BzOOH both reversibly inhibited GJIC and transiently activated mitogen-activated protein kinase, specifically, the extracellular receptor kinase at noncytotoxic conditions in WB-F344 rat liver epithelial cells, whereas the non-tumor-promoting di-tert-butylhydroperoxide did not inhibit GJIC or activate extracellular receptor kinase. di-CuOOH but not BzOOH inhibited GJIC through a phosphatidylcholine-specific phospholipase C-dependent mechanism. N-acetylcysteine (NAC) was needed to prevent a cytotoxic, glutathione-depleting effect of BzOOH, whereas di-CuOOH was noncytotoxic and did not alter glutathione levels at all doses and times tested. Pretreatment of WB-F344 cells with resveratrol, a polyphenolic antioxidant present in red wine, prevented at physiological doses the inhibition of GJIC by di-CuOOH but not from BzOOH and was effective in significantly preventing extracellular receptor kinase activation by both peroxides. NAC did not prevent any of the peroxide effects on either GJIC or extracellular receptor kinase, suggesting a specific antioxidant effect of resveratrol.

The hybrids and segregating populations obtained by crossing 4 gynoecious with 4 androecious lines were analyzed to determine the inheritance of sex expression in dioecious cucumber (Cucumis sativus L.). Sex expression of all F1 hybrids was characterized by plants with a continuous pistillate stage of flowering on the main stem. This included both gynoecious and predominantly female plants. No reciprocal cross differences were observed in the F1 and backcross generations. Backcrosses to the gynoecious parents produced plants with a continuous female stage. Backcrosses to the androecious parent produced plants with continuous pistillate, monoecious (without a continuous pistillate stage), and androecious expression in a 2:1:1 ratio, respectively. The F2 generation segregated 12:3:1 continuous pistillate, monoecious, and androecious phenotypes, respectively. Two major loci, a and acr, with epistasis are proposed to control sex expression. The a locus permits male (aa) as opposed to female (A –) flower expression. The acr locus conditions the intensity of femaleness.

Effects of 4 daylength and temperature combinations on sex expression and growth of androecious (allmale) cucumber (Cucumis sativus L.) were studied. Three of 4 androecious lines were stable for male expression under all 4 combinations. However, low temperature and short days promoted femaleness in one line causing monoecious expression. Ethylene production by androecious was compared to that of monoecious, andromonoecious, hermaphroditic and gynoecious phenotypes. Low ethylene evolution was associated with plants of androecious and monoecious phenotypes as compared to more female phenotypes. Furthermore, ethylene production by androecious plants remained low and constant throughout 30 days of growth, but a small peak in ethylene production by monoecious plants was noted. This small peak may be associated with the initiation of female flowers in monoecious phenotypes.

Hybrids from single and 3-way crosses involving gynoecious, hermaphroditic, monoecious, and androecious parent lines of cucumber (Cucumis sativus L.) were grown for 2 summers near East Lansing, Michigan. Frequencies of gynoecious hybrid plants varied significantly between years for most crosses. The femaleness (% gynoecious plants) of most single cross hybrids from gynoecious × androecious crosses was greater than ‘Pioneer’ for 1973 but not as clear-cut in 1974. The same differences were observed for 3-way crosses derived from gynoecious-hermaphroditic F1 seed parents crossed with an androecious pollen parent The differences were more marked for 1973 than 1974. However, when the femaleness of 3-way hybrids derived from the same F1 seed parents crossed with either androecious or monoecious pollen parents were compared, the androecious crosses were consistently more female. Overall, hybrids derived from androecious pollen parents were as highly female, or more so, than hybrids derived from monoecious pollen parents including hybrid ‘Pioneer’.