裙带菜配子体对三种重金属离子毒性耐受力的研究

A STUDY ON T0LERANT CAPACITY OF UNDARIA PINNATIFIDA GAMETOPHYTE T0 THE T0XICITY 0F THREE HEAVY METAL I0NS

裙带菜于1994年来自威海市俚岛养殖场．1995年2月—1997年3月，用不同浓度（0，1，10，100，1000μmol／U的Cu2+，Cd2+和Zn2+处理裙带菜配子体，研究这些重金属对其生长和代谢的影响。结果表明，Cu2+对裙带菜配子体生长的抑制效应最强：在1μmol／L时已出现抑制效应，叶绿素含量和光合作用速率明显下降，脯氨酸和丙二醇含量升高。10μmol／L时，配子体生长几乎停止；超过10μmol／L，配干体逐渐变绿，细胞解体死亡．Cd2+在1μmol／L浓度时，对裙带菜配子体生长有促进作用；100μmol／L时，对配子体生长、叶绿素含量、光合作用具较强的抑制作用，其抑制程度与Cu2+1μmol／L浓度相似；1000μmol／L下，配子体细胞很快死亡。Zn2+对裙带菜配子体的毒性很小1000μmol／L时，仍有缓慢生长．这3种金属闻子毒性强弱的顺序是Cu2+＞Cd2+＞Zn2+。

Sporophytes of U pinnaopda were collected from Lidao, Weiha in l994. Gajntophytes from the sporoPhtes were maintrined in enriched seawateL To inveshgate intO the effect of heavy metal ions on the growth from FebI-uary l995 to hah l997, the gametOPhtes were cultUred in PESI medium beated with CU+, Cd+ and zn+ at 0, l, l0, l0O, l O00pmol / L concenhaons. For the study of the influences of the metal ions on chioroPhll conten` Photosynthehc rate, proine and malondialdehyde (MDA) content of the gametoPhytes, the PESI medium beated with the i0ns at O,5, 20'40' 60, 80, l00pmol/L was employed. The culbe condihon was 25t, 3 OO0 lx, l2: l2h light: dark cycle. The intervals of measurement was 7 days fot growth and 4 days for Physiological study. CoPper, axnong the boe metal ions inveshgated. was the most toxic metal ion to the gamtophto- A 50% reduchon in growth took Plase when copper concentIation was slighuy higher than lymol / L. Growth of the gametophyte stopped after 4 days' beatmnt at l0pmol / L. The color of the cells changed from brown to green and the cells disintograted raghdly when CU+ concentration 10μmol / L. Cd2+ might facilitate the growth at low concentration (1μmol / L), but started to retard the growth at 10omol / L. The growth rate of the gametophyte was reduced by 50% at 100omol / L ca2+. The gametophytes died gradually at 1000omol / L Cd2+. Zn2+ had litile negative effect on the gametophyte even at 100omol / L but the growth was obviously inhibited at 1000omol / L (Eig. 1). After 12 days treatment at 5omol / L Cu2+, the chlorophyll content decreased by 20.3% and photosynthetic rate was 44.6% lower than that in the control. After 16,12 and 8days of the treatrment at 60,80, 100omol / L Cu2+ respechvely, the gametophytes died (Tab.1). The toxic effect of Cd2+ on the chlorophyll content and the photosynthetic rate was stronger in 5μmol / L 16 days' treatment group than in 80μmol / L 4days' heatment grouP. This result indicated that Cd2+ might accumulate in the gametophytes during the beatment period. Zn2+ had a much less toxic effect on the gametophyte than Cu2+ and Cd2+. 100μmol / L Cd2+, 16 days' heatment could make 42.9% and 36.5% reductions of chlorophyll content and photosynthetic rates of the gamtophytes, respectively. Proline and MDA contents in the gametophytes treated with 100μmol / L Cu2+ for4 days were 4.5 and 14 hmes higher than those in the controls. In the gametophytes beated with 100μmol / L Cd2+ or Zn2+ for 16 days, proline and MDA were 3 and 12 times or 1.7 and 2.7 times higher than those in the controls. The order of the metal ions toxicity is Cu2+>Cd2+ >Zn2+. The results showed that pollution of Cu2+ in coastal areasmay cause damages in the cultivation of the alga. The lethal Cu2+ and Cd2+ concentrations for the gametophyte have been identified; such concentrations can be used to screen the bosgenic cells of the gametophyte, which are integrated with metallothionein gene.