海带（Saccharina japonica）碘代谢对海水温度升高和酸化的应答与调控机制
发布时间：2019-05-23 04:12
【摘要】：海带是一种重要的大型海洋经济藻类,具有富集碘元素的生物学特性,是生物界中重要的碘存储器之一,其吸收、储存与释放过程是碘生物地球化学循环的重要组成部分。海带中碘积累的主要形态是碘化物,它参与藻体的免疫反应,可以有效清除体内的活性氧(ROS),所以,海带中的碘是一种非常有效的无机抗氧化剂。在逆境条件的刺激下,藻体中的碘会释放,在海带叶片表面以及质外体,碘化物可以和体内产生的氧化剂或者空气中的臭氧反应,从而导致大量的分子碘释放到体表。分子碘随后会被臭氧O3氧化成高吸湿性的碘氧化物,逐步形成云凝集核,从而影响O3的含量。由此可见,海带对碘元素的生物地球化学循环起到不可或缺的作用。另外,在海带的碘代谢过程中有一种关键酶—钒依赖型卤代过氧化物酶(vanadium-dependent haloperoxidase,vHPOs),在催化卤素离子与过氧化氢反应生成卤素的氧化形态的过程中发挥着重要的催化作用。此外,vHPOs还可能参与调控海带游孢子体和配子体附着发育及细胞壁增厚机制。因此,研究海带中的碘代谢机制具有一定的可行性和较高的研究价值。受人类活动与全球气候变化的双重影响,大气中二氧化碳(CO2)排放量持续增加,造成温室效应,引起了全球变暖。海洋作为一个天然的CO2储存库,吸收了人类排放CO2总量的约30%,又引起海洋酸化现象。海洋系统在碘元素的生物地球化学循环中是重要的组成部分,而海带作为海洋中重要的碘储存器,全球气候变化所引起的海洋酸化及温度升高可能会影响海带中碘元素的含量,从而影响人类食用碘的含量。另外,低潮状态下的海带会将碘释放到空气中,而我国又是世界上海带栽培面积和养殖产量最大的国家,主要养殖品种为日本真海带(Saccharina japonica),由海洋酸化引起的海带中碘含量的改变会影响碘的生物地球化学循环。由于海带中碘含量随气候变化会对人类健康及碘的生物地球化学循环两方面均有重要影响,本研究从实验生态学和分子生物学两方面探究海带(S.japonica)中碘代谢对气候变化的应答与调控机制。首先,我们通过设置不同的温度及酸化梯度,探究海带(S.japonica)对海水温度升高和酸化的应答;其次,我们对海带中碘的抗氧化机制进行了研究;最后由于vHPOs在海带碘代谢中重要的催化作用,我们在海带(S.japonica)全基因组测序的基础上,对其中的vHPOs基因家族进行鉴定和结构功能分析。本文的主要研究结果如下:1)采用单因子实验,分别研究温度和酸化诱导对海带碘代谢的影响。实验结果表明,温度变化和酸化诱导均对海带中碘含量有显著影响,在实验温度5℃,10℃,15℃,20℃,23℃范围内,海带中碘含量呈现出先升高后下降的趋势,在15℃取得最大值;酸化实验结果表明,在海水pCO2(二氧化碳分压)(400μatm,700μatm,1000μatm,1500μatm,2000μatm)范围内,海带中碘含量也呈现先升高后下降的趋势,在1000μatm取得最大值,且酸化培养对海带碘吸收具有促进作用。此外,15℃和20℃与酸化耦合在一定程度上对海带中的碘含量具有促进作用。在海区中开展的中试酸化实验也验证了海洋酸化条件下海带的个体大小以及总碘含量明显高于正常条件下的海带,但总体上随着海带的生长其碘含量逐渐下降。另外,本研究通过对海带中无机形态碘的测定发现,碘离子的变化趋势与总碘的变化趋势一致,而碘酸根离子不在检测限度内。最后,通过在海带的培养体系中添加100μg/m L的低聚古罗糖醛酸,发现在3h时海带中碘释放速率达到最大。结果显示当海带在氧化应激状态时,体内碘离子大量释放与活性氧反应来消除活性氧,起到了抗氧化作用。2)通过生物信息学方法在S.japonica基因组中检索鉴定出75个vHPO基因,其中58个钒依赖型碘过氧化物酶(vanadium-dependent iodoperoxidase,vIPO),17个钒依赖型溴过氧化物酶(vanadium-dependent bromoperoxidase,vBPO)。通过与其他真核和原核生物的vHPOs全长蛋白质序列构建系统进化树,发现所有的vHPOs蛋白质被分为三个不同的亚家族:钒依赖型氯过氧化物酶(vanadium-dependent chloroperoxidase,vCPO)、vBPOs和vIPOs。通过进一步分析进化树拓扑结构发现海洋藻类中的vHPO起源于真菌的vCPO,其中vBPO在红藻和褐藻中独立进化,海带中vIPO由褐藻中的vBPO祖先进化而来。3)通过对海带(S.japonica)雌雄配子体、小孢子体及成熟孢子体不同部位的转录组数据分析发现,vHPOs在海带不同世代及组织中具有明显的表达特异性。在海带不同世代中,雌、雄配子体中表达的vHPO的数目最多,其次是小孢子体世代,最后是成熟孢子体。在成熟孢子体的不同组织中,梢部和根茎表达的vHPO数目最多。另外,为了从分子生物学水平上揭示胁迫条件下vHPOs基因表达量的变化,我们对高温及CO2充气培养3h下S.japonica的荧光定量PCR结果分析发现高温及CO2充气培养条件下各有8个vHPO基因表达量明显增加,推测这些基因在高温及酸化胁迫条件下的海带碘的吸收中发挥重要作用。
[Abstract]:Zosterae marinae is an important large-scale marine economic algae, which has the biological characteristics of enriching the iodine element, is one of the important iodine storage in the biological community, and the absorption, storage and release process of the kelp is an important part of the biogeochemical cycle of the iodine. The main form of iodine accumulation in the kelp is iodide, which participates in the immune response of the algae body and can effectively remove the active oxygen (ROS) in the body, so the iodine in the kelp is a very effective inorganic antioxidant. Under the stimulation of the stress condition, the iodine in the algae body is released, and in the surface of the laminaria leaf and the mass outer body, the iodide can react with an oxidizing agent or an ozone generated in the body to cause a large amount of molecular iodine to be released to the body surface. The molecular iodine is then oxidized to the high-hygroscopic iodine oxide by the ozone O3, and the cloud aggregation core is gradually formed, so that the content of the O3 is affected. It can be seen that kelp plays an indispensable role in the biogeochemical cycle of iodine. In addition, in the process of iodine metabolism of the kelp, a key enzyme, such as vanadium-dependent haloperoxidase (vHPOs), plays an important catalytic role in the process of generating the oxidation state of the halogen by the reaction of the catalytic halogen ion and the hydrogen peroxide. In addition, vHPOs may also be involved in the regulation of the attachment and development of the sporophytes and gametophytes of Laminaria japonica and the mechanism of cell wall thickening. Therefore, the study of the iodine metabolism mechanism in the kelp has a certain feasibility and higher research value. The double effects of human activities and global climate change, the continued increase in carbon dioxide (CO2) emissions in the atmosphere, contributing to global warming. The oceans, as a natural CO2 repository, absorb about 30% of the total amount of CO2 emitted by humans and cause ocean acidification. The marine system is an important part of the biogeochemical cycle of the iodine element, while the sea tangle is an important iodine storage in the ocean, and the ocean acidification and the temperature rise caused by the global climate change can affect the content of the iodine element in the kelp, thereby affecting the content of the human edible iodine. in addition, the kelp in the low-water state can release the iodine into the air, and the country is the country with the largest culture area and the breeding yield in the world, and the main breeding variety is the Saccharina japonica, The change of iodine content in the kelp caused by ocean acidification can affect the biogeochemical cycle of iodine. Since the content of iodine in the sea tangle has an important influence on the biological and geochemical cycle of human health and iodine, the response and regulation mechanism of iodine metabolism in the sea tangle (S. japonica) to climate change is explored from the aspects of experimental ecology and molecular biology. First, we study the response of the sea-tangle (S. japonica) to the temperature rise and the acidification of the sea water by setting different temperature and acidification gradients; secondly, we study the anti-oxidation mechanism of iodine in the kelp; and finally, because of the important catalytic effect of vHPOs in the iodine metabolism of the kelp, On the basis of the whole genome sequencing of the S. japonica, we identified and structure the vHPOs gene family. The main results of this paper are as follows:1) The effect of temperature and acidification on the metabolism of kelp iodine was studied by single factor experiment. The experimental results show that the change of temperature and the induction of acidification have a significant effect on the content of iodine in the kelp, and the content of iodine in the kelp is at the temperature of 5 鈩，
本文编号：2483590
[Abstract]:Zosterae marinae is an important large-scale marine economic algae, which has the biological characteristics of enriching the iodine element, is one of the important iodine storage in the biological community, and the absorption, storage and release process of the kelp is an important part of the biogeochemical cycle of the iodine. The main form of iodine accumulation in the kelp is iodide, which participates in the immune response of the algae body and can effectively remove the active oxygen (ROS) in the body, so the iodine in the kelp is a very effective inorganic antioxidant. Under the stimulation of the stress condition, the iodine in the algae body is released, and in the surface of the laminaria leaf and the mass outer body, the iodide can react with an oxidizing agent or an ozone generated in the body to cause a large amount of molecular iodine to be released to the body surface. The molecular iodine is then oxidized to the high-hygroscopic iodine oxide by the ozone O3, and the cloud aggregation core is gradually formed, so that the content of the O3 is affected. It can be seen that kelp plays an indispensable role in the biogeochemical cycle of iodine. In addition, in the process of iodine metabolism of the kelp, a key enzyme, such as vanadium-dependent haloperoxidase (vHPOs), plays an important catalytic role in the process of generating the oxidation state of the halogen by the reaction of the catalytic halogen ion and the hydrogen peroxide. In addition, vHPOs may also be involved in the regulation of the attachment and development of the sporophytes and gametophytes of Laminaria japonica and the mechanism of cell wall thickening. Therefore, the study of the iodine metabolism mechanism in the kelp has a certain feasibility and higher research value. The double effects of human activities and global climate change, the continued increase in carbon dioxide (CO2) emissions in the atmosphere, contributing to global warming. The oceans, as a natural CO2 repository, absorb about 30% of the total amount of CO2 emitted by humans and cause ocean acidification. The marine system is an important part of the biogeochemical cycle of the iodine element, while the sea tangle is an important iodine storage in the ocean, and the ocean acidification and the temperature rise caused by the global climate change can affect the content of the iodine element in the kelp, thereby affecting the content of the human edible iodine. in addition, the kelp in the low-water state can release the iodine into the air, and the country is the country with the largest culture area and the breeding yield in the world, and the main breeding variety is the Saccharina japonica, The change of iodine content in the kelp caused by ocean acidification can affect the biogeochemical cycle of iodine. Since the content of iodine in the sea tangle has an important influence on the biological and geochemical cycle of human health and iodine, the response and regulation mechanism of iodine metabolism in the sea tangle (S. japonica) to climate change is explored from the aspects of experimental ecology and molecular biology. First, we study the response of the sea-tangle (S. japonica) to the temperature rise and the acidification of the sea water by setting different temperature and acidification gradients; secondly, we study the anti-oxidation mechanism of iodine in the kelp; and finally, because of the important catalytic effect of vHPOs in the iodine metabolism of the kelp, On the basis of the whole genome sequencing of the S. japonica, we identified and structure the vHPOs gene family. The main results of this paper are as follows:1) The effect of temperature and acidification on the metabolism of kelp iodine was studied by single factor experiment. The experimental results show that the change of temperature and the induction of acidification have a significant effect on the content of iodine in the kelp, and the content of iodine in the kelp is at the temperature of 5 鈩，
本文编号：2483590
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