Upregulation of pyrophosphate: fructose 6-phosphate 1-phosphotransferase (PFP) activity in strawberry.

Pyrophosphate: fructose 6-phosphate 1-phosphotransferase (PFP) is a cytosolic enzyme catalyzing the first committed step in glycolysis by reversibly phosphorylating fructose-6-phosphate to fructose-1,6-bisphosphate. The position of PFP in glycolytic and gluconeogenic metabolism, as well as activity patterns in ripening strawberry, suggest that the enzyme may influence carbohydrate allocation to sugars and organic acids. Fructose-2,6-bisphosphate activates and tightly regulates PFP activity in plants and has hampered attempts to increase PFP activity through overexpression. Heterologous expression of a homodimeric isoform from Giardia lamblia, not regulated by fructose-2,6-bisphosphate, was therefore employed to ensure in vivo increases in PFP activity. The coding sequence was placed into a constitutive expression cassette under control of the cauliflower mosaic virus 35S promoter and introduced into strawberry by Agrobacterium tumefaciens-mediated transformation. Heterologous expression of PFP resulted in an up to eightfold increase in total activity in ripe berries collected over two consecutive growing seasons. Total sugar and organic acid content of transgenic berries harvested during the first season were not affected when compared to the wild type, however, fructose content increased at the expense of sucrose. In the second season, total sugar content and composition remained unchanged while the citrate content increased slightly. Considering that PFP catalyses a reversible reaction, PFP activity appears to shift between gluconeogenic and glycolytic metabolism, depending on the metabolic status of the cell.

Microbial, chemical and physical aspects of citrus waste composting.

Citrus waste supplemented with calcium hydroxide and with a C/N ratio of 24:1, pH of 6.3 and moisture content of 60% was composted by piling under shelter. With regular turning over of the pile and replenishment of moisture, the thermic phase lasted for 65-70 days and composting was completed after 3 months. Compost thus prepared had an air-filled porosity of 14%, water-holding capacity of 590 ml l(-1), bulk density of 1.05 g cm(-3) and conductivity of 480 mS m(-1). Phosphorus content (in mg l(-1)) was 15, potassium 1,170, calcium 362, magnesium 121, sodium 32, chloride 143, boron 0.31, and water-soluble nitrogen and organic matter 126 and 4788, respectively. Total carbon amounted to 8.85% and total nitrogen to 1.26% of the dry weight, giving a C/N ratio of 7. Mature compost showed some, but acceptable, levels of phytotoxicity. Raw citrus waste was predominantly colonised by mesophilic yeasts. Thermophilous microorganisms present during the thermic phase mainly comprised the bacterial species Bacillus licheniformis, B. macerans and B. stearothermophilus and, to a lesser extent, fungi such as Absidia corymbifera, Aspergillus fumigatus, Emericella nidulans, Penicillium diversum, Paecilomyces variotii, Rhizomucor pusillus, Talaromyces thermophilus and Thermomyces lanuginosus. Bacteria prevalent in the final product included B. licheniformis, B. macerans, Proteus vulgaris, Pseudomonas aeruginosa, P. fluorescens, P. luteola and Serratia marcescens, whereas fungi isolated most frequently comprised Aspergillus puniceus, A. ustus, E. nidulans. Paecilomyces lilacinus, T lanuginosus, yeasts and a basidiomycetous species, probably Coprinus lagopus.

The Phytoplasma Associated with Ramu Stunt Disease of Sugarcane Is Closely Related to the White Leaf Phytoplasma Group.

Ramu stunt disease of sugarcane (ScRS) was responsible for large yield losses in commercial sugarcane varieties (interspecific hybrids of Saccharum spp.) in the Ramu Valley in northeast Papua New Guinea during the late 1980s. Losses were total in the cultivar Ragnar; Q90 and Yasawa were also affected but Cadmus and Q107 were resistant. Since that time, replanting with resistant cultivars has kept the disease under control. The disease spreads rapidly in susceptible cultivars, where it results in severe stunting of the cane and a yellow mottled striping of the leaves. Although several attempts have been made to detect a viral pathogen, no evidence for viral etiology exists and the causal agent remains unknown. With a nested polymerase chain reaction (PCR) of general phytoplasma primers from the 16S rDNA (1), phytoplasma-specific products were consistently amplified from the leaves of field-grown sugarcane, from sugarcane with ScRS symptoms grown in the glasshouse at IACR-Rothamsted, UK, and from samples of the putative vector collected at Ramu, the delphacid plant hopper Eumetopina flavipes Muir, which had been found to transmit symptoms of Ramu stunt in pot trials (2). Digestion of the amplimers with restriction enzymes RsaI and HaeIII gave profiles that matched those of members of the sugarcane white leaf (SCWL) phytoplasma group. The DNA sequence of the intergenic spacer region of the phytoplasma associated with ScRS showed a 95.98% homology with that of SCWL, suggesting that this newly discovered phytoplasma can provisionally be placed in this group. The 16S-23S intergenic spacer sequence has been submitted to GenBank (accession no. AF 106061). References: (1) C. P. R. Cronjé et al. Ann. Appl. Biol. 133:177, 1998; (2) L. S. Kuniata et al. J. Aust. Entomol. Soc. 33:185, 1994.

Central venous catheterization for parenteral nutrition. Experience at Groote Schuur Hospital.

The aim of this study was to determine the incidence of complications of catheterization for total parenteral nutrition (TPN) in patients of the Parenteral Nutrition Unit of Groote Schuur Hospital. During the 2-year study period, 218 central venous catheters were inserted in 170 patients. The preferred technique of percutaneous infraclavicular subclavian venepuncture with subsequent subcutaneous tunnelling using a silicone elastomere catheter is described. The incidence of major complications of catheter insertion was 4,5% (pneumothorax 4, subclavian artery puncture 6). There was a 2,7% incidence of catheter malpositioning (requiring repositioning) at initial insertion. The mean duration of catheterization was 12,9 days. During this period there was a 6,9% incidence of mechanical complications (occluded lines 13, extravascular infusion 2). Catheter-related sepsis was suspected in 37 cases (16,9%) and all these catheters were removed, but in only 7 cases (3,2%) was the sepsis proved to be catheter-related. There was no correlation between the duration of catheterization and the development of catheter-related sepsis. Furthermore, there was no increase in the incidence of catheter sepsis in patients with sepsis before catheterization.

Home parenteral nutrition in a patient with Crohn's disease. A case report.

Total parenteral nutrition (TPN) carried out by the patient at home is a new concept in the treatment of intestinal failure. We describe a patient with Crohn's disease who has extensive involvement of the small intestine with resultant severe malabsorption, and who was therefore treated with 'home' TPN for 4 months. During this treatment there were no serious complications. The disabling symptoms present before hyperalimentation was commenced disappeared, and overall clinical improvement has been maintained for a further 6 months after TPN therapy. This case illustrates the feasibility of safe TPN at home in selected patients who have access to specialized hyperalimentation units.

Continuous positive pressure ventilation in children with bronchopneumonia.

The application of a small end-expiratory pressure of 5 cmH2O to the assisted ventilation of nineteen children (mean age 19 months) with bronchopneumonia was compared with intermittent positive pressure ventilation. Within 1 h of introducing continuous positive pressure ventilation the alveolar-to-arterial oxygen gradient was reduced in most patients, with an increase in functional residual capacity and a decrease in total pulmonary blood shunt. Physiological dead space was also reduced, a feature not observed in other studies, and the significance of this finding is discussed. The use of continuous positive pressure ventilation in broncho-pulmonary infection was shown to be effective even at small pressures, and can be recommended especially for patients requiring long-term ventilation.