【摘要】 于 1 999年 1 0月 ,采用pH漂移技术研究了海带幼孢子体的无机碳源利用途径以及无机碳对幼孢子体光合碳利用的影响。结果表明 ,在天然海水中 (pH =8 1— 8 3 ) ,海带幼孢子体外源无机碳的利用形式主要是HCO-3 ,HCO-3 由质膜外碳酸酐酶 (CA)将HCO-3 水解成CO2 ,以游离CO2 形式扩散进入细胞 ,占全部无机碳供应的 75 %。游离CO2 只占所吸收总无机碳的 2 5 % ;在游离CO2 浓度接近于零 (pH =9 1 )时 ,幼孢子体的全部无机碳源均来自于HCO-3 的水解。提高海水中无机碳的浓度能增加海带对无机碳的利用量 ,当无机碳浓度达到3 5mmol L时 ,无机碳的利用速率达到最大值 ,说明天然海水中的无机碳不能满足其最大生长的需要更多还原

【Abstract】 Adopting the pH drift technique in Oct. 1999, different forms and mechanisms of inorganic carbon utilization have been investigated on the juvenile sporophyte of L. japonica×L. longissima in a closed system by means of various inhibitors: acetazolamide (Az), 4′,4′ diisothiocyanatosilbene 2, 2 disulfonic acid (DIDS) and 4 acetamido 4′ isothiocyano 2,2′ stibene disulfonate (SITS). The results suggest that (1) the light saturation point of juvenile sporophyte of L. japonica×L. longisima is 200μE/(m 2·s). (2) juvenile sporophyte of L. japonica×L. longissima has a higher pH compensation point--9.79 which is not affected by the weight of material and light intensity, showing HCO - 3 is useful. Az, an inhibitor of external CA, can strongly inhibit carbon uptake of juvenile sporophyte of L. japonica×L. longissima . External CA dehydrating HCO - 3 to free CO 2 is the main pathway of inorganic carbon utilization by juvenile sporophyte of L. japonica×L. longissima , accounting for 75% of total inorganic carbon acquisition in natural seawater (pH=8.1-8.3) and 100% when the concentration of free CO 2 is close to zero (pH=9.1). (3) With regard to the effect of different concentrations of inorganic carbon on carbon acquisition by juvenile sporophyte of L. japonica×L. longissima has been studied, the rate of inorganic carbon acquisition by juvenile sporophyte of L. japonica×L. longissima would increase with an increase in the concentration of inorganic carbon from 2.0mmol/L to 3.5mmol/L, indicating that the concentration of inorganic carbon in natural seawater cannot meet the need of optimal growth of L. japonica×L. longissima .更多还原