Production of cucumber fruits from the culture of ‘Marketmore-76’ plantlets
A procedure to produce fruits from cultured shoot tips of Cucumis sativus L. cultivar ‘Marketmore-76’ in vitro is described. Four-week-old shoot tips, derived from sterile germinated seedlings on a MS medium, were cultured in a 3.8-1 Mason jar using an automated plant culture system. Tips readily generated roots, leaves and flowers after another 4 to 8 weeks in culture. Administration of compressed air at a 300 ml/min flow rate for 30 min 10 or 15 times a day induced the development of parthenocarpic fruits from flowers. Fruits, up to 170 mm long by 35 mm diameter, were obtained within 30 to 45 d after flower opening.
In vitro flowering in regenerated shoots of spinach
Spinach (Spinacia oleracea L.) flowers in response to long photoperiods. It is considered to be a dioecious species, but monoecious types also occur (Janick and Stevenson, 1955). Isolated stem tips of spinach seedlings have flowered in response to long days, exhibiting the same photoperiodic reactions as the intact plants (Culafic, 1973). Several plant species have been induced to flower in vitro from shoot-tip explants (Al Wareh et al., 1989; Tang et al., 1983; Tisserat and Galletta, 1988) and nodes (Dickens and van Staden, 1985). The in vitro flowering of shoots derived from callus cultures has also been reported for a few species (Al Wareh et al., 1989; Yoshikawa and Furuya, 1983). Our objective was to establish a system for in vitro flower induction in regenerated spinach shoots. Modification of a previously described tissue culture method for the regeneration of ‘Fall Green’ spinach from leaf-derived callus (Al-Khayri et al., 1991) was employed. Leaves from 3-month-old ‘High Pack’ spinach were surface-sterilized in 70% ethanol for 30 set and 1% NaOCl (20% Clorox) for 5 min and then rinsed three times in sterile distilled water. Callus was induced from 5mm leaf disks on MS medium (Murashige and Skoog, 1962) containing (mg·liter-1) 2 kinetin and 0.5 (2,4-dichlorophenoxy)acetic acid (2,4-D). Shoots were regenerated under a 10-h photoperiod of cool-white fluorescent light (65 μmol·m -2·s-l) at 22 ± 3C on MS medium containing (mg·liter-1) 2 kinetin, 0.01 2,4-D, and 1 gibberellic acid (GA,). Callus induction and shoot regeneration media were supplemented with (mg·liter-1) 100 myo -inositol, 0.4 thiamine·HCl, 0.5 nicotinic acid, 0.5 pyridoxine·HCl, and 3% (w/v) sucrose. Media were solidified with 0.8% agar (agar-agar/gum agar; Sigma Chemical Co., St. Louis). The medium pH was adjusted to 5.8 before being autoclaved at 121C and 103 kPa for 15 min. After 8 to 12 weeks, regenerated shoots
On the fractionation of β-lactoglobulin and α-lactalbumin
Abstract Existing methods for the preparation of α-lactalbumin and β-lactoglobulin are examined critically. It is proposed that the most satisfactory method for the preparation of the whey protein fraction from bovine milk is (NH 4 ) 2 SO 4 fractionation. A number of new gentle procedures for the fractionation of the whey proteins are compared with some existing methods. The distribution of total protein at various stages is determined by total Kjeldahl nitrogen and the kind of protein by starch-gel electrophoresis. The effect of variables, such as pH, salt concentration and temperature on the separation of α-lactalbumin and serum albumin from β-lactoglobulin is studied. Differences in the behavior ( e.g. solubility) of genetic variants of β-lactoglobulin are noted. The solubility of each of the major whey proteins, under similar conditions to those used in the fractionation, is compared with its solubility in the whey protein mixture. The understanding gained of factors important in the fractionation is used in recommending new procedures for α-lactalbumin and β-lactoglobulin isolation.