【作者】 刘素；

【导师】 唐学玺；

【作者基本信息】 中国海洋大学 ， 生态学， 2009， 博士

【摘要】 本文综合运用实验生态学、统计学及电镜技术与方法,探讨了大型褐藻—海带(Laminaria japonica Aresch)早期发育对UV-B辐射增强及与其它环境因子交互作用的响应,为明确全球环境变化,特别是UV-B辐射持续增强对大型海藻早期发育的影响作用提供科学依据。1.海带早期发育对UV-B辐射增强的响应剂量为11.7和23.4 J m-2 d-1UV-B辐射对游孢子的附着无显著影响,而当UV-B辐射剂量大于35.1 J m-2 d-1时,游孢子的附着率显著低于对照组。低剂量UV-B辐射组(11.7-35.1 J m-2 d-1)中的胚孢子萌发率均大于93%,而高剂量组(46.8-70.2 J m-2 d-1)的萌发率在78.5%-88.5%之间,表明高剂量的UV-B辐射对胚孢子萌发的影响显著。游孢子释放120 h后,剂量为35.1-70.2 J m-2 d-1UV-B辐射处理组中仅有极少数胚孢子发育为配子体,大部分已死亡。与对照组相比,低剂量的UV-B辐射下幼孢子体发生率显著降低,雌配子体克隆发生率显著上升。然而,低剂量UV-B辐射对配子体性别比、雌配子体和幼孢子体的生长率无显著影响。研究表明,增强的UV-B辐射能显著影响海带早期发育阶段的多项指标(如游孢子附着、胚孢子萌发、配子体和幼孢子形成等),但对配子体性别、配子体和幼孢子体生长无明显影响。2.温度和UV-B辐射对海带早期发育的交互作用5℃下,UV-B辐射(11.7,23.4和35.1 J m-2 d-1)刺激了海带胚孢子的萌发;而10,15、20℃与UV-B辐射组合处理对胚孢子的萌发无显著影响。除15℃下配子体发生率与UV-B辐射剂量变化无显著关系外,其他温度(5,10和20℃)下,配子体发生率随UV-B辐射剂量的增加而显著降低。20℃和UV-B辐射(0,11.7,23.4和35.1 J m-2 d-1)之间存在显著交互作用,导致了20℃下雄配子体比例和雌配子体发育率随UV-B辐射剂量的增加而显著降低。第30d时,10℃下各实验组中的幼孢子体发生率均显著高于其它温度下相同水平的UV-B辐射组,而20℃下雌配子体克隆的发生率较高。研究表明,温度和UV-B辐射对海带早期发育的影响存在显著的交互作用,改变了海带配子体形成、生长、发育以及幼孢子体和雌配子体的发生等发育进程。3.温度与UV-B辐射对海带配子体细胞超微结构的影响温度和UV-B辐射组合处理对海带配子体细胞超微结构的影响,主要表现在细胞壁厚度、色素体结构以及蛋白核的数量和形态变化上。5和10℃下UV-B辐射导致配子体细胞壁明显减薄,而15℃下细胞壁明显增厚。上述3个温度下,UV-B辐射组中配子体的色素体片层结构均模糊不清,且类囊体出现断裂或粘联。配子体细胞中的蛋白核数量在UV-B辐射的刺激下明显增加,UV-B辐射组中的配子体细胞中均含2个以上的蛋白核。此外,在配子体线粒体大小、质体小球数量以及产生畸形细胞的形态等方面,各温度与UV-B辐射处理组合组与空白组之间均存在一定程度的差异。综合前一章的实验结果表明,高温下UV-B辐射能刺激配子体细胞壁厚度增加,在一定程度上能减轻UV-B辐射对色素体、线粒体等细胞器的伤害。4.营养元素(氮、磷)和UV-B辐射组合处理对海带生活史早期生长发育的交互作用UV-B辐射能显著影响胚孢子萌发、配子体形成、幼孢子体和雌配子体克隆发生,且与不同的氮、磷浓度之间存在显著的交互作用。配子体形成的最适条件为氮浓度N-0,磷浓度P-0且UV-B辐射水平为UVB-0;氮浓度为N-1,磷浓度为P-2或P-1,UV-B辐射水平为UVB-0时最有利于幼孢子体发生;氮浓度为N-0,磷浓度为P-1且UV-B辐射为UVB-2时是雌配子体克隆形成的最佳条件。UV-B辐射对雌配子体大小和相对生长率(RGR)影响的主效应不显著,而雌配子体的相对生长率受氮、磷浓度和UV-B辐射剂量间二维交互作用(N*P,N*UVB,P*UVB)的影响显著。海水中氮、磷浓度变化对雄配子体比例无显著影响,而UV-B辐射以及UV-B辐射与N、P浓度间的二维(N*P,N*UVB,P*UVB)和三维(N*P*UVB)交互作用显著影响了雄配子体比例。研究表明,UV-B辐射和海水中氮、磷浓度对海带早期发育阶段的交互作用十分明显,且交互作用会随着海带发育时期的变化而呈现出较大差异。5.不同光合有效辐射(PAR)强度和光质条件下海带早期发育对UV-B辐射增强的响应方差分析显示,PAR强度为35μmol photons m-2 s-1时,UV-B辐射对配子体形成、雌配子体发育和叶绿素含量的不利影响最小,且对雌配子体克隆的发生有一定的促进作用,不利于幼孢子体的形成。光质与UV-B辐射之间的交互作用显著影响了配子体形成、雌配子体发育、幼孢子体和雌配子体克隆发生及叶绿素a的含量。与白光相比,蓝光能显著缓解UV-B辐射对配子体发生率、雌配子体发育和叶绿素a含量的不利影响;红光下UV-B辐射对配子体发生率的不利影响小于白光,却加剧了UV-B辐射对雌配子体发育和叶绿素a含量的不利影响;绿光对海带早期发育最为不利。蓝光、红光和绿光均显著抑制了幼孢子体的形成。蓝光对雌配子体克隆发生有一定的刺激作用,蓝光与UV-B辐射剂量为23.4 J m-2 d-1的处理组合是本实验中雌配子体克隆发生的最适条件。研究表明,不同的PAR强度、光质与UV-B辐射之间存在显著的交互作用,对配子体形成、雌配子体发育、幼孢子体和雌配子体克隆发生及叶绿素a含量产生明显的影响。6. UV-B辐射对海带幼孢子体生长和生理的影响辐射处理期间(第2-10 d),3个辐射剂量(低剂量:11.7;中剂量:46.8;高剂量:93.6 J m-2 d-1)处理组的海带幼孢子体体长和体重的相对增长率显著低于对照组(即0 J m-2 d-1);第6-10 d内,低剂量处理组和高剂量处理组的叶绿素a含量与对照组相比呈现出完全相反的变化趋势,前者显著高于对照组,后者显著低于对照组;中、高剂量处理组中的ATP酶活性在整个实验期间均显著低于对照组,而低剂量组与对照组无显著差异。培养海水中氮、磷元素缺乏与中剂量UV-B辐射联合作用条件下的海带幼孢子体体长、体重相对增长率与中剂量UV-B辐射单独处理组无显著差异;辐射处理初期(第2-4 d),氮、磷缺乏与中剂量UV-B辐射共同处理组的ATP酶活性明显高于单独辐射处理组,后期(第10 d)则显著低于单独辐射处理组;氮、磷元素的缺乏加剧了中剂量UV-B辐射对幼孢子体叶绿素a含量的影响,氮、磷缺乏与中剂量UV-B辐射组合处理组的叶绿素a含量显著低于中剂量UV-B辐射单独处理组。在高剂量UV-B辐射处理过程中附加一定强度的光合有效辐射(photosynthetically active radiation,PAR,400-700nm)能在一定程度上减轻UV-B辐射对幼孢子体生长和生理状况的影响。更多还原

【Abstract】 ? For comprehensive understanding the effects of global enviromental changes, especially of increasing UV-B radiation, on the growth and development of macroalgae, the responses of the early developmental stages of Laminaria japonica Aresch to the interaction between enhanced UV-B radiation and other environmental factors were studied in the laboratory based on the integrated techniques and methods with experimental ecology, data statistics analysis and electronic microscopy.1. The response of the early developmental stages of L.japonica to enhanced UV-B radiationThe low UV-B radiations (11.7-23.4 J m-2 d-1) had no significant effects on zoospores attachment, but when the UV-B dose > 35.1 J m-2 d-1 the attachment decreased significantly compared with the control. Germination of embryospores was >93% under the low (11.7 - 35.1 J m-2 d-1) doses, and in the range of 78.5% - 88.5% under the high (46.8 - 70.2 J m-2 d-1) UV-B doses, indicating a significant radiation effect. Under the higher UV-B exposure (35.1 - 70.2 J m-2 d-1), all of the few gametophytes formed from embryospores died 120 h post-release. After exposure to the low UV-B radiation (11.7 - 23.4 J m-2 d-1), the formation of sporophytes decreased and the female gametophyte clones increased compared with the control. However, the sex ratio and the relative growth of female gametophytes/sporophytes had not significantly changed. According to the results, enhanced UV-B radiation has a significant effect on the early development of L. japonica under laboratory conditions, suggesting that the UV-B radiation could not be overlooked as one of the important environmental factors influencing the ontogeny of macroalgae living in marine ecosystems.2. The interaction between temperature and UV-B radiation on the early development of L.japonicaEmbryospore germination was stimulated by UV-B radiation (11.7,23.4 and 35.1 J m-2 d-1) at 5℃, and UV-B radiations had no significant effects on embryospore germination at 10,15 and 20℃. Gametophytes incidences were irrelevant to the doses of UV-B radiation at 15℃, however, the incidences of gametophytes significantly decreasing as UV-B doses increasing at the three other temperatures. Both the percentage male gametophytes and the fecundity of female gametophytes decreasing with UV-B radiation dose increasing at 20℃showed that the significant interaction existed between 20℃and UV-B radiation(0,11.7,23.4 and 35.1 J m-2 d-1). At 30th d, the incidences of sporophytes in all experimental groups at 10℃were obviously higher than that of the other combinations of the same UV-B doses and other temperatures respectively. However, the highest incidences of female gametophytes clones occured at 20℃.The results suggested that significant interactions existed between temperature and UV-B radiation, which significantly influenced the early development of L.japonica, such as the incidence and development of gametophytes, incidences of both sporophytes and female gametophytes clones.3. The interaction between temperature and UV-B radiation on gametophyte ultrastructuresThe main ultrastructural influences on gametophytes of L.japonica by the combinations of temperature and UV-B radiation were thickness of cell wall, chloroplast structures and the changes in number and morphology of pyrenoid. At both 5 and 10℃, UV-B radiation caused gametophyte cell wall thin significantly, however, cell wall became thicken obviouly at15℃. The lamellar structure of chloroplast was unclear and thylakoid appeared fracture or stick under the treatments ?of combinations of the above three temperatures and UV-B radiation. The number of pyrenoid seemed to be stimulated by UV-B radiation and more than two pyrenoids in gametophyte cells were detected. Meanwhile, the differences in the size of mitochondria, the number of lipid globuli and the morphology of abnormal cells were also discovered between the control groups and the combination groups of temperature and UV-B radiation. Considering the results of the previous chapter, we concluded that proper high temperature could reduce the damages on chloroplast, mitochondria and other organelles caused by the UV-B radation due to the thickness of cell wall increased at high temperature.4. The interaction of nutrient elements (nitrogen, phosphorus) and UV-B radiation on the growth and development of L.japonica in its early life historyOur data suggested that there were significant interactions between UV-B radiation and different nitrogen and phosphorus concentration, which significantly affected the embryospores germination, gametophytes formation, young sporophyte and female gametophyte clones incidence. The optimal conditions for gametophytes formation, young sporophyte incidence and female gametophyte colones incidence were the combination of N-0, P-0 and UVB-0, the combination of N-1, P-2 or P-1 and UVB-0, and the combination of N-0, P-1 and UVB-2 respectively. The main influence caused by UV-B radiation alone on the female gametophyte size and relative growth rate (RGR) was not significant, but the RGR was affected significantly by the two-dimensional interaction of nitrogen, phosphorus concentration and UV-B radiation (N * P, N * UVB, P * UVB). The proportion of male gametophytes was significantly affected by UV-B radiation, the two-dimensional (N * P, N * UVB, P * UVB) and the three-dimensional ( N * P * UVB) interactions, but the nitrogen or phosphorus concentrations had no significant effects. The results indicated that the interactions between UV-B radiation and nitrogen or phosphorus concentration in seawater may change the growth and development of L.japonica in its early life history. 5. The response of the early developmental stages of L.japonica to enhanced UV-B radiation under different PAR intensity and light quality conditionsVariance analysis showed that the adverse effects of UV-B radiation on the formation of gametophyte, female gametophyte development and chlorophyll content were smallest when PAR intensity was at 35μmol photons m-2 s-1, and the PAR intensity could promote the incidence of female gametophytes clones which would further restrain the incidence of young sporophytes. The interaction between light quality and UV-B radiation had significant impacts on the formation of the gametophytes, female gametophytes development, young sporophytes or female gametophyte clones happened and Chl-a content. Compared with white light, blue light could significantly alleviate the adverse effects of UV-B radiation on the incidences of gametophytes, female gametophytes development and Chl-a content. The adverse effects of UV-B radiation under red light on the incidences of gametophytes were less than white light, and green light was the most disadvantaged for the early development of L.japonica. Blue light could stimulate the incidence of female gametophytes clones and the optimum condition for clones happen was the combination of blue light and 23.4 J m-2 d-1 dose of UV-B in our experiments. The results suggested that the interaction of PAR intensity, light quality and UV-B radiation could significantly effect the formation of the gametophytes, female gametophytes development, young sporophytes or female gametophyte clones incidence and Chl-a content.6. The effect of UV-B radiation on the growth and physiological of the young sporophytes of L.japonicaDuring the period from the 2th d to 10th d post UV-B radiation, the length and weight relative growth rates of young sporophytes under three doses of UV-B radiation treatments(11.7 J m-2 d-1, 46.8 J m-2 d-1, 93.6 J m-2 d-1) were significantly lower than that of the control (0 J m-2 d-1); the changes of Chl-a content from the 6th to the 10th day under the UV-B doses 11.7 J m-2 d-1 and 93.6 J m-2 d-1 showed inverse, which indicated that low UV-B dose could provoke the increase of Chl-a content and high dose could inhibit; the ATPase activities of young sporophytes treated with the two doses 46.8 J m-2 d-1 and 93.6 J m-2 d-1 were significantly lower than that of the control, and no obviously differences detected between the low dose 11.7 J m-2 d-1 and the control. Under the conditions of the shortage of N/P element accompanying with the UV-B dose 46.8 J m-2 d-1, there were no significantly difference between the relative growth rate of young sporopytes and that of just under the UV-B dose 46.8 J m-2 d-1; During the early period of the experiment (from 2th d to 4th d), the ATPase activities treated with the shortage of N/P element and the UV-B dose 46.8 J m-2 d-1 simultaneously were obviously higher than that of treated with the UV-B dose 46.8 J m-2 d-1 only, however, inverse changes appeared at the late stage; the Chl-a content under the coation of the shortage of N/P and UV-B radiation was significantly lower than that of the UV-B dose 46.8 J m-2 d-1 only, which suggested that the shortage of N/P intensified the impact of UV-B radiation on Chl-a content. Our results also suggested that a certainly intensity of photosynthetically active radiation could relieve the influence of the high UV-B dose 93.6 J m-2 d-1 on the growth and physiology of the young sporophytes.更多还原