No abstract

Plastid DNA was isolated from the chloroplasts of tomato (Lycopersicon esculentum var Traveler 76) leaves and the chromoplasts of ripe tomato fruit. Comparisons of the two DNAs were made by restriction endonuclease analysis using PvuII, HpaI, and BglI. No differences in the electrophoretic banding patterns of the restricted plastid DNAs were detected, indicating that no major rearrangements, losses, or gains of plastid DNA accompany the transition from chloroplast to chromoplast.Central to the ripening process in tomato fruit is the transition of chloroplasts in the green fruit to chromoplasts in the ripe fruit.In this process the morphology and biochemical activities of the plastids are profoundly altered. The granal thylakoids characteristic of chloroplasts degenerate and carotenoid inclusions form (5,13). Chl is lost and photosynthetic activities cease, whereas synthesis of carotenoid pigments increases dramatically (12).Chloroplasts contain DNA which encodes proteins functional in photosynthesis and protein and RNA components of the plastid protein synthesis apparatus (2, 17). Other plastids also contain DNA, sometimes in quantities greater than chloroplasts of the same plant (15). However, the role of plastid DNA in the function of these organelles is not known.This study addresses the question of whether changes in the plastid DNA are involved in the transition from chloroplast to chromoplast. Plastid DNAs were isolated from the leaves and from the red-ripe fruit of tomato. These DNAs were digested with restriction enzymes PvuII, HpaI, and Bgl I, and the electrophoretic banding patterns of the fragments were compared. Any rearrangements or other changes in plastid DNA that occur during the plastid transition would alter the pattern of restriction endonuclease cleavage sites and be detected as a change in size of restriction fragments. In previous work, Iwatsuki et al. (6)

A procedure using nutritionally minimal media is presented for the plating isolation, but not enumeration, of various catalase-negative microorganisms from soil. Casida (1) and Gledhill and Casida (3-5) described the isolation and characterization of certain numerically dominant catalase-negative microbial populations of soil. These included a

A procedure using nutritionally minimal media is presented for the plating isolation, but not enumeration, of various catalase-negative microorganisms from soil.