Summary• The effects are shown here of genetic manipulation of invertase on fruit sugar metabolism in tomato.• Introgression of the acid invertase gene on chromosome 3 from Lycopersicon pimpinellifolium (an accession containing high invertase activity) into Lycopersicon esculentum (with relatively low activity) was used to study effects on fruit development and both sugar composition and content.• The L. pimpinellifolium parent fruit had higher fruit invertase activities, greater hexose contents and lower sucrose accumulation that the L. esculentum parent. A strong correlation between fruit invertase activity and soluble sugar content was observed only in the L. pimpinellifolium parent and not in the homozygous fruit from either cross. In all cases high soluble acid invertase activities prevented sucrose accumulation and led to the build-up of hexoses.• The introgression of the invertase locus from L. pimpinellifolium into L. esculentum did not result in higher soluble solids in the progeny than in the L. esculentum parent, but it did modify their relative composition. Changes in the invertase gene composition alone are not sufficient to increase fruit soluble solids in tomato.

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Sucrose is the photoassimilate transported from the leaves to the fruit of tomato yet the fruit accumulates predominantly glucose and fructose. Hydrolysis of sucrose entering the fruit can be accomplished by invertase or sucrose synthase. Early in tomato fruit development there is a transient increase in sucrose synthase activity and starch which is correlated with fruit growth and sink strength suggesting a regulatory role for sucrose synthase in sugar import. Using an antisense sucrose synthase cDNA under the control of a fruit-specific promoter we show that sucrose synthase activity can be reduced by up to 99% in young fruit without affecting starch or sugar accumulation. This result calls into question the importance of sucrose synthase in regulating sink strength in tomato fruit.

In red blood cells as well as in platelets there appears to be a decrease in adenine nucleotides during storage under blood bank conditions. This can be decreased by use of anticoagulant preservatives with higher phosphate content than the standard ACD solution, through the addition of adenine and inosine. Maintenance of higher ATP levels appears to be related to longer circulating life span after transfusion into patients in the case of red blood cells but not platelets. Inosine and more alkaline preservative medium also contribute to the maintenance of 2,3-DPG levels in red blood cells, and with it to the maintenance of normal hemoglobin dissociation curves and thus oxygen-carrying capacity. Certain nucleoside analogs may contribute to the preservation of platelets and of whole blood by their platelet-aggregation inhibitory activity. Platelet-aggregation inhibitors may also be useful in preventing thromboembolic episodes with potentially greater safety than anticoagulants.