THE EFFECTS OF LEAD ON DELTA-AMINOLEVULINIC-ACID DEHYDRATASE ACTIVITY, GROWTH, HEMOGLOBIN CONTENT, AND REPRODUCTION IN DAPHNIA-MAGNA

• The effects of continuous exposure to lead for various periods and recovery in clean water on δ-aminolevulinic acid dehydratase (ALA-D) activity, hemoglobin content, growth, and reproduction were studied in Daphnia magna. Steady-state inhibition of ALA-D activity was reached within 2 days in 16, 64, and 256 μg Pb liter−1, but restoration in clean water was prolonged in relation to previous exposure. In spite of the inhibition of ALA-D activity hemoglobin content increased after 2 days in 16 and 24 μg Pb liter−1. Furthermore, hemoglobin content in previously exposed animals increased during recovery in clean water. Maximum hemoglobin content (2.9 times control value) was found after 2 days recovery of animals exposed to 64 μg Pb liter−1. These findings suggest that some enzyme(s) other than ALA-D in the biosynthetic pathway of hemoglobin formation is (are) more sensitive to lead. Growth, in contrast to reproduction, was stimulated by low concentrations of lead (<64 μg Pb liter−1), although in 256 μg Pb liter−1 growth was also significantly impaired. After 19 days the 16 and 50% reproductive impairment concentrations were ⩽1 and 10 μg Pb liter−1, respectively.

Ämnesord

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Environmental Sciences & Ecology; Toxicology

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