Abstract
Gamma radiation from a 60Co source at a dose of 10 Kr caused no visible algal cell damage in podetia of Cladonia verticillata up to weeks after irradiation. One after a 1,000 Kr dose algal cell damage was evident; 4 weeks later cytoplasmic breakup was apparent in 20-30% of the cells. When compared with a non-irradiated control, 10 Kr irradiated podetia had a stimulated phosphorous uptake, and 1,000 Kr irradiated podetia had a decreased uptake 24 hours and 6 weeks after irradiation. Algal cultures were only obtained from normal and 10 Kr irradiated lichen segments. During the incubation period for algal isolation squamule growth appeared on the nonand 10 Krirradiated segments. Certain lichen species have been shown to be quite resistant to chronic and acute doses of radiation that would normally kill most other plants within a few months (Brodo, 1964; Hale, 1967; Woodwell & Gannutz, 1967; Jones & Platt, 1969). Lichens also have the unusual ability to absorb ions from various sources beyond their expected needs and without apparent harm. Radioactive fallout (Gorham, 1959) and naturally occuring radioisotopes (Beasley & Palmer, 1966) are accumulated and concentrated by some lichens without any apparent damage. In an effort to understand the manner in which radiation affects the lichen, we studied Cladonia verticillata (Hoffm.) Schaer. to determine the effects of acute gamma irradiation in regard to 1) cellular damage, 2) phycobiont growth, and 3) 32P uptake. MATERIALS AND METHODS Cladonia verticillata podetia and squamules were collected during July and August in Keweenaw and Houghton counties of Michigan's Upper Peninsula. The specimens were Study supported in part by NSF-URP grant number GY 7552 and in part by AEC grant number AT( 11-1 )-2085. 2 Department of Biological Sciences, Michigan Technological University, Houghton, Michigan 49931. FIGURES 1-8. Algal cells of Cladonia verticillata. All approximately X200. 1. Cells of a 1 week control. 2-3. Cells of a 5 week control. 4. Cells after receiving a 10 Kr dose. 5. Cells weeks after receiving a 10 Kr dose. One damaged cell (arrow) is evident. 6. Cells after receiving a 1,000 Kr dose. 7. Cells weeks after receiving a 1,000 Kr dose. All cells but two (arrow) appear damaged. 8. Cells weeks after receiving a 1,000 Kr dose. All cells but one (arrow) appear normal. This content downloaded from 157.55.39.195 on Tue, 26 Apr 2016 05:08:00 UTC All use subject to http://about.jstor.org/terms 1972] PULLUM & ERBISCH: RADIATION OF CLADONIA VERTICILLATA 49
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