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首页> 外文期刊>Marine biology >Effects Of Light Exposure On The Retention Of Kleptoplastic Photosynthetic Activity In The Sacoglossan Mollusc Elysia Viridis
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Effects Of Light Exposure On The Retention Of Kleptoplastic Photosynthetic Activity In The Sacoglossan Mollusc Elysia Viridis

机译：光照对Sacoglossan软体动物Elysia Viridis保持增生塑形光合活性的影响

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The effects of light exposure on the photosynthetic activity of kleptoplasts were studied in the sacoglossan mollusc Elysia viridis. The photosynthetic activity of ingested chloroplasts was assessed in vivo by non-destructively measuring photophysiological parameters using pulse amplitude modulation (PAM) fluorometry. Animals kept under starvation were exposed to two contrasting light conditions, 30 μmol photons m~(-2) s~(-1) (low light, LL), and 140 μmol photons m~(-2) s~(-1) (high light, HL), and changes in photosynthetic activity were monitored by measuring the maximum quantum yield of photosystem Ⅱ (PSII), F_v/F_m, the minimum fluorescence, F_o, related to chlorophyll a content, and by measuring rapid light-response curves (RLC) of relative electron transport rate (rETR). RLCs were characterised by the initial slope of the curve, α_(RLC), related to efficiency of light capture, and the maximum rETR level, rETR_(m,RLC), determined by the carbon-fixation metabolism. Starvation induced the decrease of all photophysiological parameters. However, the retention of photosynthetic activity (number of days for F_v/F_m > 0), as well as the rate and the patterns of its decrease over time, varied markedly with light exposure. Under HL conditions, a rapid, exponential decrease was observed for F_v/F_m, α_(RLC) and rETR_(m,RLC), F_o not showing any consistent trend of variation, and retention times ranged between 6 and 15 days. These results suggested that the retention of chloroplast functionality isrnlimited by photoinactivation of PSII reaction center protein Dl. In contrast, under LL conditions, a slower decrease in all parameters was found, with retention times varying from 15 to 57 days. F_v/F_m, α_(RLC) and rETR_(m,RLC) exhibited a bi-phasic pattern composed by a long phase of slow decrease in values followed by a rapid decline, whilst F_o decayed exponentially. These results were interpreted as resulting from lower rates of Dl photoinactivation under low light and from the gradual decrease in carbon provided by photosynthesis due to reduction of functional photosynthetic units.
机译：研究了在整枝软体动物Elysia viridis中光照对角膜基质的光合活性的影响。体内摄入的叶绿体的光合作用活性是通过使用脉冲幅度调制（PAM）荧光法非破坏性地测量光生理参数来评估的。使处于饥饿状态的动物暴露于两种相反的光照条件下：30μmol光子m〜（-2）s〜（-1）（弱光，LL）和140μmol光子m〜（-2）s〜（-1）通过测量光系统Ⅱ（PSII）的最大量子产量F_v / F_m，与叶绿素a含量有关的最小荧光F_o并测量快速光响应来监测高光（HL）和光合活性的变化。相对电子传输速率（rETR）的曲线（RLC）。 RLC的特征是曲线的初始斜率α_（RLC）与光捕获的效率有关，而最大rETR水平rETR_（m，RLC）由碳固定代谢确定。饥饿导致所有光生理参数降低。但是，光合作用的保留时间（F_v / F_m> 0的天数）以及其速率和其随时间下降的模式，随曝光量的变化而显着变化。在HL条件下，观察到F_v / F_m，α_（RLC）和rETR_（m，RLC）快速，指数下降，F_o没有显示出任何一致的变化趋势，保留时间为6到15天。这些结果表明，通过PSII反应中心蛋白D1的光灭活来限制叶绿体功能的保留。相反，在LL条件下，发现所有参数的下降较慢，保留时间从15天到57天不等。 F_v / F_m，α_（RLC）和rETR_（m，RLC）表现出一种双相模式，由值的缓慢下降和快速下降的长阶段组成，而F_o呈指数下降。这些结果被解释为是由于在弱光下D1光灭活的速率较低以及由于功能性光合作用单位的减少而使光合作用提供的碳逐渐减少所致。

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