Polyribosomes from Aging Apple and Cherry Fruit

Abstract

The sequence of events which occurs during the ripening of the PasseCrassane pear fruit have been previously studied. In this work, we have investipted the ripening of another climacteric fruit (Pyrus maims L. cv Golden Delicious) and of a nonclimacteric fruit (Prunus avium L. cv Bigarreau Napoleon). We show that both climacteric fruits exhibit the same precimacteric sequence of events. Differences exist, however, between the Golden Delicious apple and the Passe-Crassane pear in that the protein synthesis capacity of the two fruits is not the same during the over-ripening period. On the other hand, a noncimacteric fruit, the Bigarreau Napoleon cherry, does not show an increase in its protein synthesis capacity during the over-ripening period.The discovery by Kidd and West (14) ofclimacteric respiration in apples, has allowed fruits to be separated into two classes (1) on the basis of their respiratory behavior during ripening: climacteric fruits, such as apples, which undergo a large increase in respiration (climacteric rise) accompanied by marked changes in composition and texture, and nonclimacteric fruits such as cherries, which show no changes in respiration associated with distinct changes in the composition of the fruit.Ripening fruit undergoes changes in RNA and protein metabolism (2,8,12, 19, 20 Extraction of Polyribosomes. Procedures described elsewhere (5, 6), for the extraction and purification of polyribosomes from 5-g samples of lyophilized pear tissues were modified as follows to maximize polyribosomal yield. With apple pulp tissues, the pellet obtained after ultracentrifugation at 105,000g was resuspended in buffer up to 0.9 ml and aliquots (0.3 ml) of resuspended polyribosomes were layered on linear (15-60% w/v) sucrose gradients. With apple peel tissues, the extraction solution contained j3-mercaptoethanol (55 mM) and the pellet obtained after ultracentrifugation at 105,000g was resuspended in buffer up to 0.6 ml. With cherries, extraction was performed on 4 g of pulverized material by homogenization in 25 ml of cold extraction solution containing 0.6 M Tris (pH 9), 55 mm ,3-mercaptoethanol, 3% PEG, 160 mM KCI, 35 mM MgCI2, 7% sucrose, 5 mM EGTA, and 2.5 g insoluble PVP (Polyclar AT

Changes in mRNA and Protein during Ripening in Apple Fruit (Malus domestica Borkh. cv Golden Delicious)

“…In conclusion, the suggestion that apple fruit ripening involves changes in gene expression (10,12) is confirmed here. The results indicate changes at both the mRNA and protein level which coincide with increasing internal ethylene concentration and decreasing fruit firmness.…”

“…During apple ripening there is an increase in the activity ofenzymes such as ,B-galactosidase (2) and 1 -aminocyclopropane-1 -carboxylic acid synthase (16), and commercial storage practices have been shown to delay such increases (3,5). Hulme et al (12) found that the incorporation of radioactive precursors into RNA production is preceded by a burst in mRNA synthesis and ribosome production (10). The aim of the present study was to investigate the role ofgene expression in apple fruit ripening by examining changes in fruit mRNA and protein populations during the ripening process.…”

Aging of Cylinders Excised from Pulp Tissues of the `Golden Delicious' Apple

“…After the 'wound peak' of mRNA and ribosomes, which occurs on day 3, a sharp increase in mRNA and large polysomes occurs on day 6. After the respiratory peak which takes place on day 1 Figure 6 and Table I show that, without prior storage at 4C, apple fruits stored at 1 5C exhibit a synthesis ofribosomes (found only in pulp tissues) on day 11 which has been previously linked with ethylene synthesis prior to increased malic enzyme activity and the respiratory climacteric on day 15 (6). After this sequence of events, post-climacteric apples show two different increases in amounts of linked mRNA ribosomes on days 29 and 47.…”