Production of very-high-amylose potato starch by inhibition of SBE A and B

High-amylose starch is in great demand by the starch industry for its unique functional properties. However, very few high-amylose crop varieties are commercially available. In this paper we describe the generation of very-high-amylose potato starch by genetic modification. We achieved this by simultaneously inhibiting two isoforms of starch branching enzyme to below 1% of the wild-type activities. Starch granule morphology and composition were noticeably altered. Normal, high-molecular-weight amylopectin was absent, whereas the amylose content was increased to levels comparable to the highest commercially available maize starches. In addition, the phosphorus content of the starch was increased more than fivefold. This unique starch, with its high amylose, low amylopectin, and high phosphorus levels, offers novel properties for food and industrial applications.

A minor form of starch branching enzyme in potato (Solanum tuberosum L.) tubers has a major effect on starch structure: cloning and characterisation of multiple forms of SBE A

Full length cDNAs encoding a second starch branching enzyme (SBE A) isoform have been isolated from potato tubers. The predicted protein has a molecular mass of 101 kDa including a transit peptide of 48 amino acids. Multiple forms of the SBE A gene exist which differ mainly in the length of a polyglutamic acid repeat at the C-terminus of the protein. Expression of the mature protein in Escherichia coli demonstrates that the gene encodes an active SBE. Northern analysis demonstrates that SBE A mRNA is expressed at very low levels in tubers but is the predominant isoform in leaves. This expression pattern was confirmed by Western analysis using isoform specific polyclonal antibodies raised against E. coli expressed SBE A. SBE A protein is found predominantly in the soluble phase of tuber extracts, indicating a stromal location within the plastid. Transgenic potato plants expressing an antisense SBE A RNA were generated in which almost complete reductions in SBE A were observed. SBE activity in the leaves of these plants was severely reduced, but tuber activity was largely unaffected. Even so, the composition and structure of tuber starch from these plants was greatly altered. The proportion of linear chains was not significantly increased but the average chain length of amylopectin was greater, resulting in an increase in apparent amylose content as judged by iodine binding. In addition, the starch had much higher levels of phosphorous.

Perforation of a Meckel's diverticulum during laparoscopic cholecystectomy

Laparoscopic procedures incur risks and complications that differ from their "open" counterparts. Although rare, injury to asymptomatic umbilical remnants (eg, Meckel's diverticulum) is one of these unique complications.

Production of embryogenic callus from nonembryonic explants of Norway Spruce Picea abies (L.) Karst

Callus has been induced on needle and bud explants from 2, 6 and 26 year old Picea abies (L.) Karst, trees. Seventy seven percent of the needle explants from the youngest material was productive compared to 0.2% for the old tree. New embryogenic sections appeared in the non-embryogenic callus derived from 2, 6 and 26 year old trees after prolonged culture and was promoted by the use of an established embryogenic callus line in a nurse culture system.

Multicenter evaluation of the hemodynamic effects of bisoprolol in patients with mild to moderate hypertension

Twenty-six patients with mild-to-moderate essential hypertension participated in a 6-week outpatient, multicenter, randomized, double-blind, placebo-controlled two-way crossover study to assess the hemodynamic effects of bisoprolol (20 mg QD) at steady state. Hemodynamic assessments included sitting blood pressure, heart rate, and left-ventricular ejection fraction by radionuclide ventriculography after 7 days of bisoprolol or placebo at trough (24 h post-dose) and peak (3 h post-dose) values. The group adjusted mean ejection fraction was not significantly different in patients receiving bisoprolol compared with the placebo group at either peak or trough measurements; in fact, means in patients taking bisoprolol were slightly higher than in the placebo group. No symptomatic hypotension was documented. Blood pressure, measured 24 hours after dosing, was significantly lower in those receiving bisoprolol when compared with the placebo group, by 7.7 mm Hg and 9 mm Hg for diastolic and systolic blood pressure, respectively. Similarly, mean values of heart rate were 10 beats/min lower in the bisoprolol patients than in the placebo group. Only headache and insomnia occurred as adverse events. Bisoprolol (20 mg QD) effectively lowered blood pressure over a 24-hour period without significantly reducing ejection fraction or causing adverse clinical or biochemical events.

Phenolic synthesis and phenylalanine ammonia-lyase activity in suspension cultures of Acer pseudoplatanus L

Phenolic metabolism is influenced by the levels of sucrose, nitrogen and 2,4 dichlorophenoxyacetic acid (2,4-D) in the growth medium. Chromatographic evidence suggests that the principle products are polymers of leucocyanin, (-) epicatechin and (+) catechin, constituting condensed tannins. Comparison of ethanolic cell extracts with extracts from plant organs shows that although these compounds are present in parts of the plant they are not the major phenolics.Cells maintained in a modified Heller's medium containing 9.0×10(-7) M 2,4-D produce increased levels of tannins from mid passage (day 12) onwards. The presence of 2,4-D at 9.0×10(-6) M supresses this response and increased initial sucrose levels cause the amount of tannins to be greater. At the period when tannin levels increase the standard medium is exhaused of its nitrogen sources, urea and nitrate. Increased initial nitrogen levels delay the beginning of increased tannin production and the addition of urea or 2,4-D to cultures already containing high levels of tannins causes the tannin content per gram fresh weight and per culture to decline. These results indicate an antagonism between tannin synthesis and nitrogen metabolism. The activity of phenylalanine ammonia-lyase EC 4.1.1.5. (PAL) estimated by a spectrophotometric method in acetone powders derived from Acer cells increases three to four fold at the onset of increased tannin synthesis and then declines sharply. The phase of high PAL activity correlates with the exhausion of the medium nitrogen sources.

Changes in the phenolic metabolism of suspension cultures of Acer pseudoplatanus L. Caused by the addition of 2-(chloroethyl)phosphonic acid (CEPA)

2-(Chloroethyl)phosphonic acid (CEPA) inhibited the rise in tannin production and phenylalanine ammonia-lyase EC 4.1.1.5 (PAL) activity shown by Acer cells in media containing 9.0×10(-7) M 2,4-D for a period of 2-3 days after its addtion.