Decreased synthesis of mitochondrial protein in the senescent cells of pear fruit

Romani, Roger J.; Fisher, L.K.

doi:10.1016/0024-3205(66)90040-3

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…1 where the dashed line could be taken t o represent the course of the homeostatic response. This interpretation is consonant with the earlier observations that RNA (Richmond and Bide 1967), protein (Richmond and Bide 1966) and mitochondrial (Romani and Fisher 1966) synthesis in ripening fruit tissues is highest in the early phases of the climacteric and low or non-existent at the climacteric peak. The fact that mitochondria (Bain and Mercer 1964) and mitochondrial function (Theologis and Laties 1978) remain largely unaffected throughout the climacteric, and beyond, may reflect the quasi-autonomy of mitochondria (Mahler et al 1975) and their apparent capacity for self-maintenance (Romani et al 1974).…”

Section: Homeostasis and The Climactericsupporting

confidence: 89%

Metabolic Integrity and Postharvest Homeostasis ? A Brief Review

Romani

1978

J Food Biochemistry

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Metabolism in fruit, as in all forms of life, encompasses the maintenance of cellular integrity and responsiveness to stress. It is proposed that this homeostatic tendency may, when combined with improved control (genetic, molecular) of ontogenetic development, provide a basis for prolonged storage life. Homeostasis may also be the underlying cause of increased metabolic activity in ripening tissues as manifested by the respiratory climacteric.

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Section: Homeostasis and The Climactericsupporting

confidence: 89%

Metabolic Integrity and Postharvest Homeostasis ? A Brief Review

Romani

1978

J Food Biochemistry

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“…In particular, intracellular events in ripening avocado (2), apple (11), and pear (8) fruits have been examined with reference to the well characterized but little understood climacteric phase. A transition from an active to a more quiescent state has been suggested for the climacteric cells based on declining rates of total protein (27), mitochondrial protein (32) and total RNA synthesis (28). Since Decreases in total ribosomes, in their functional capacity, and in the proportion existing as polymeric forms have been observed in some aging mammalian and microbial cells (10,20,29).…”

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confidence: 99%

The Ribosomes of Pear Fruit

Romani

1970

Plant Physiol.

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Maceration at liquid nitrogen temperatures, use of polyvinylpyrrolidone, and careful pH control are essential to the isolation of ribosomes and polysomes from deciduous fruit tissue. Characteristics of the ribosomes and constituent RNA are described. Superimposed intracellular radiation injury stimulates the synthesis of new ribosomes and underscores a major transition in the dynamics of the ribosomal system coincident with the climacteric rise.Fruits and leaves have often been used as sources of tissue committed to senescence and death. In particular, intracellular events in ripening avocado (2), apple (11), and pear (8)

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“…(21) and in synthesis of mitochondrial protein (22) coincident with the climacteric rise in pear fruit. Moreover, Romani et al (26) have demonstrated that the ability of pear cells to compensate for radiation damage to the mitochondrial system is lost or markedly impaired as fruits reach the climacteric peak.…”

Section: Discussionmentioning

confidence: 99%

Ripening and in Vitro Retention of Respiratory Control by Avocado and Pear Mitochondria

Ozelkok¹,

Romani²

1975

Plant Physiol.

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The retention of respiratory control ("surv-ival") The absence, or near absence, of ultrastructural change in the mitochondria of ripening pear (1), apple (17), and tomato (9) fruits plus the persistent capacity of mitochondria to oxidize substrates and demonstrate respiratory control throughout the climacteric of many fruits, including avocado (10, 14), tomato (8), apple (11-13), and banana (7) attest to the fact that mitochondria in senescing fruit cells remain functionally sound. Nonetheless, Romani et al. (26) discerned a ripening, age-related change in the mitochondrial system based on the observation that mitochondria in climacteric pears can neither withstand nor recover from doses of ionizing radiation that are tolerated by mitochondria in preclimacteric fruit.It has since been shown that isolated pear and avocado mitochondria can maintain RC' at 25 C for several hr (23,24). In analogy to experiments with long lived chloroplasts (6, 18), the maintenance of RC at 25 C has been referred to (24) as "survival." It seems reasonable to assume that survival is a more critical index of organelle integrity than a single point-in-time assessment of RC and should be helpful in understanding the status of mitochondria in ripening fruit. In the present study, the possible relationship between the capacity of mitochondria to survive in vitro and fruit ripening and senescence was investigated. 5 mM ,B-mercaptoethanol; 0.2%c PVP). The hard tissues of preclimacteric avocados were macerated by using a porcelain hand grater submerged in the isolation medium. A ratio of 1:3 (w/v), tissue to isolation medium, was used. After sedimentation at 14,000g the mitochondria were dispersed in wash medium (0.25 M sucrose; 50 mM K phosphate, pH 7.2; 0.1C% BSA; 5 mM 3-mercaptoethanol), centrifuged for 5 min at 1,200g to remove clumped particles and then at 8,000g for 10 min. The final pellets were dispersed in a few tenths ml of wash medium resulting in mitochondrial suspensions containing 20 to 30 mg protein /ml. Similar procedures were followed in the isolation of mitochondria from Bartlett pears with the exceptions, based on prior experiments (25), that the PVP concentration was increased from 0.2 to 0.5% (w,/v) and the pH during maceration was maintained within 6.7 to 7 by dropwise addition of I M KOH.Assay and Incubation. Oxidative activity of mitochondria at 25 C was measured with a Clark-type polarographic electrode. The sequence of additions into the cuvette was as follows: 3 ml of reaction medium, mitochondrial suspension, and repeated additions of ADP until anaerobiosis. The reaction mixture consisted of 0.25 M sucrose, 66 mm potassium phosphate buffer (pH 7.2), 1 mM MgCl,, 3.3 J.M CoA, 33 J.M thiamine pyrophosphate, 0.1 mM NAD, 1 mg/ml BSA, 100 j.g'ml chloramphenicol, and 10 mM substrate. Unless otherwise indicated, a-KG was supplied as substrate for both incubation and assay.For incubation at 25 C, done according to Romani and Ozelkok (24), 3 ml of reaction medium were placed in a 20-ml beaker 239 www.plantphysiol....

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Decreased synthesis of mitochondrial protein in the senescent cells of pear fruit

Cited by 7 publications

References 7 publications

Metabolic Integrity and Postharvest Homeostasis ? A Brief Review

Metabolic Integrity and Postharvest Homeostasis ? A Brief Review

The Ribosomes of Pear Fruit

Ripening and in Vitro Retention of Respiratory Control by Avocado and Pear Mitochondria

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