Effect of Irradiation of Carbon Ions Beam on the Photosynthetic Pigments and Oxidative Activity of Scenedesmus quadricauda

Abstract

Chlorophyll a,chlorophyll b,carotenoid,superoxide dismutase( SOD) and malondialdehyde( MDA) of Scenedesmus quadricauda were measured to study the injury mechanism of different doses( 10- 80 Gy) after irradiation by 80 MeV / u12C6 +of Heavy Ion Research Facility( HIRFL,Lanzhou,China). The obtained results were as follows: 1) Chlorophyll a( Chl a),chlorophyll b( Chl b) and carotenoid were measured in different culture times after irradiation. For low-dose groups( 10- 20 Gy),contents of Chla,Chlb and carotenoid decreased slightly or did not vary significantly; for middle-dose groups( 40- 60 Gy),contents of Chl a,Chl b and carotenoid increased apparently,and then went down to the level of control group; for high- dose group( 80 Gy),contents of Chl a,Chl b and carotenoid were impacted severely and did not show sign of recovery. 2) Malonaldehyde( MDA) was measured in different culture times after irradiation. For low-dose group( 10 Gy),the injury of membrane lipid appeared immediately after irradiation,it became lighten after 8 h, and then recovered to the level of control group within 24- 48 h; for the 20 Gy group,the content of MDA decreased immediately,and then came back to the normal level; for middle and high-dose groups( 40- 80 Gy), the injury of membrane lipid did not happen instantly,while it became obviously in 24- 48 h,and did not has the ability of recovery to the normal level. 3) Superoxide dismutase( SOD) was measured in different culture times after irradiation. For low-dose group( 10 Gy),the activity of SOD rose significantly,and then declined to the normal level in 8 h; for middle-dose groups( 20- 60 Gy),the activity of SOD ascended markedly and went back to the normal within 48 h; for high-dose group( 80 Gy),the activity of SOD did not has a sign of increment,while it descended obviously and did not recover to the normal within 48 h.