Contamination of Vegetation by Tetraethyl Lead

Cannon, Helen L.; Bowles, Jessie M.

doi:10.1126/science.137.3532.765

Cited by 185 publications

(39 citation statements)

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“…The large concentration of airborne lead accumulates in soils (9, 33). Lead pollutants are incorporated into animal tissues (4,8) and have been shown to inhibit various enzyme systems (12,29,31,34).…”

Section: Introductionmentioning

confidence: 99%

Inhibition of Photosystem II in Isolated Chloroplasts by Lead

Miles¹,

Brandle²,

Daniel³

et al. 1972

Plant Physiol.

102

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Inhibition of photosynthetic electron transport in isolated chloroplasts by lead salts has been demonstrated. Photosystem I activity, as measured by electron transfer from dichlorophenol indophenol to methylviologen, was not reduced by such treatment. However, photosystem II was inhibited by lead salts when electron flow was measured from water to methylviologen and Hill reaction or by chlorophyll fluorescence. Fluorescence induction curves indicated the primary site of inhibition was on the oxidizing side of photosystem II. That this site was between the primary electron donor of photosystem II and the site of water oxidation could be demonstrated by hydroxylamine restoration of normal fluorescence following lead inhibition.A great deal of interest has been generated recently by the effect of lead on plants and animals (7). The large concentration of airborne lead accumulates in soils (9, 33). Lead pollutants are incorporated into animal tissues (4,8) and have been shown to inhibit various enzyme systems (12,29,31,34).Despite these effects on animal systems, little is known about the effect of lead on plant enzymes. We know that lead is taken up and transported in plants (3. 4, 24, 32, 33) and can decrease cell division at very low concentration (13,14). Koeppe and Miller (23) examined the effect of lead salts on corn mitochondria and found an inhibition of electron transport, especially in the absence of phosphate.Because of the increasing concentration of lead in our environment, the toxigenic effects of lead on animal enzyme systems, the increasing reliance we have upon photosynthesis to sustain our environment, and the similarity of the electron transport chain of mitochondria to that of photosynthetic electron transport, we feel a preliminary investigation of the effects of lead upon the light reactions of photosynthesis seems to be warranted. Isolation of Chloroplasts. The procedure used was a modification of the technique of Jagendorf and Avron (19). Fresh leaves (20 g) were deveined and washed twice with distilled water. They were cut into small pieces and macerated in a cold blender (Eberbach No. 8475) operated at full speed for 10 sec with 60 ml of cold grinding medium which consisted of 0.8 M sucrose, 20 mm Tricine, and 10 mm NaCl adjusted to a final pH of 7.8. Defatted bovine serum albumin (50 mg) was included in the grinding medium during each extraction. The resulting homogenate was strained through Miracloth (Chicopee Mills, Inc., N.Y.) into chilled centrifuge tubes which were then placed into a refrigerated centrifuge and accelerated to 1,500g and immediately turned off. The supernatant obtained was centrifuged at 1,500g for 8 min to sediment chloroplasts which were resuspended in fresh grinding medium and diluted to a concentration of 1 mg of chlorophyll per ml as determined by the method of Arnon (2). MATERIALS AND METHODSHypotonic chloroplast fragments were prepared as described by Jagendorf and Uribe (22) by resuspension of chloroplasts in 25 ml of cold 10 mm NaCl for 20 min and ...

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Section: Introductionmentioning

confidence: 99%

Inhibition of Photosystem II in Isolated Chloroplasts by Lead

Miles¹,

Brandle²,

Daniel³

et al. 1972

Plant Physiol.

102

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“…The result of this process was a concentration of Pb deposits in the cell wall outside the plasmalemma. Similar deposits were observed in stems and leaves suggesting that Pb was transported and deposited in a similar manner.Many researchers have shown that plants will accumulate Pb either from soil, stem, or foliar application (1,3,8,9,13,14,16,25). However, the reports conflict as to the amounts accumulated and the amounts that can be translocated.…”

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Localization of Lead Accumulated by Corn Plants

Malone¹,

Koeppe²,

Miller³

1974

Plant Physiol.

172

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Light and electron microscopic studies of corn plants (Zea mays I.) exposed to Pb in hydroponic solution showed that the roots generally accumulated a surface Pb precipitate and slowly accumulated Pb crystals in the cell walls. The root surface precipitate formed without the apparent influence of any cell organelles. In contrast, Pb taken up by roots was concentrated in dictyosome vesicles. Dictyosome vesicles containing cell wall material fused with one another to encase the Pb deposit. This encased deposit which was surrounded by a membrane migrated toward the outside of the cell where the membrane surrounding the deposit fused with the plasmalemma. The material surrounding the deposit then fused with the cell wall. The result of this process was a concentration of Pb deposits in the cell wall outside the plasmalemma. Similar deposits were observed in stems and leaves suggesting that Pb was transported and deposited in a similar manner.Many researchers have shown that plants will accumulate Pb either from soil, stem, or foliar application (1,3,8,9,13,14,16,25). However, the reports conflict as to the amounts accumulated and the amounts that can be translocated. Little has been done to localize the Pb accumulated within an organ, although Hammett (5-7) indicated that much of the Pb was associated with cell walls and nuclei, and Suchodoller (24) found that it was concentrated in the root cortex.It was the purpose of this research to study the localization of accumulated Pb and characterize the method of accumulation as specifically as possible. MATEIUALS AND METHODSCorn (Zea mays L. Wf9 X M14) was grown by a standard hydroponic procedure (19) in a greenhouse or was grown on paper toweling in a moist chamber.

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“…In the open field, the Pb content of the upper 2 cm of soil declined from about 150 fig g" 1 at a point 0.3 m from the curb to 12 ng g" 1 at 18.3 m from the curb, and remained at that level to 30 m from the curb. In the 3 m between the curb and the near drip line of the windbreak, the Pb content of the soil diminished from 220 to 140 ng g" 1 . However, this range of Pb content was about 50% more than that of the open field at a similar distance from the road.…”

Section: Resultsmentioning

confidence: 99%

“…Commuter and truck traffic passed the windbreak at 65 to 73 km hr" 1 . A survey station maintained by the Connecticut Department of Transportation 1.6 km north of the windbreak recorded the traffic flow during 1973 (Table I).…”

Section: Traffic Flowmentioning

confidence: 99%