To understand the function of ascorbic acid (ASC) in root development, the distribution of ASC, ASC oxidase, and glutathione (GSH) were investigated in cells and tissues of the root apex of Cucubita maxima. ASC was regularly distributed in the cytosol of almost all root cells, with the exception of quiescent centre (QC) cells. ASC also occurred at the surface of the nuclear membrane and corresp...

Interspecific hybridization among the three most economically important cultivated species of Cucurbita spp., Cucurbita pepo, C. moschata, and C. maxima can be made but not readily. By means of various pollination measures, different mating systems, and varying selection methods, nine advanced interspecific-bridge lines were developed, in which the crossing barrier among the species and the mal...

Attempts to increase protein stability by insertion of novel disulfide bonds have not always been successful. According to the two current models, cross-links enhance stability mainly through denatured state effects. We have investigated the effects of removal and addition of disulfide cross-links, protein flexibility in the vicinity of a cross-link, and disulfide loop size on the stability of ...

The relationships between damage-induced electropotential waves (EPWs), sieve tube occlusion, and stop of mass flow were investigated in intact Cucurbita maxima plants. After burning leaf tips, EPWs propagating along the phloem of the main vein were recorded by extra- and intracellular microelectrodes. The respective EPW profiles (a steep hyperpolarization/depolarization peak followed by a prol...

The assimilation of nitrate in plants involves the reduction of nitrate to ammonia in two steps. The first step requires nitrate reductase, a nitrate-inducible enzyme. When seedlings of squash (Cucurbita maxima L.) were treated with nitrate, both nitrate reductase activity and protein were induced in the cotyledons. Poly(A)(+) RNA was prepared from cotyledons of nitrate-treated seedlings and wa...

Energy dispersive x-ray analysis was used to study the composition of certain protein body components in Cucurbita maxima cotyledons. The globoid crystal was rich in phosphorus, potassium, and magnesium. This elemental composition provides further evidence that the globoid crystal in squash cotyledon protein bodies is composed of phytin, a myoinositol hexaphosphoric acid salt of potassium and m...

Twelve pumpkin cultivars (Cucurbita maxima D.), cultivated in Iowa, were studied for their seed oil content, fatty acid composition, and tocopherol content. Oil content ranged from 10.9 to 30.9%. Total unsaturated fatty acid content ranged from 73.1 to 80.5%. The predominant fatty acids present were linoleic, oleic, palmitic, and stearic. Significant differences were observed among the cultivar...