The competitive dynamics of toxic and non toxic ribotypes of the harmful dinoflagellate Alexandrium tamarense

有害甲藻亚历山大藻的有毒和无毒核糖体的竞争动态

• 批准号: NE/G011362/1
• 金额: $ 8.83万
• 依托单位: Scottish Association For Marine Science
• 依托单位国家: 英国
• 项目类别: Training Grant
• 财政年份: 2009
• 资助国家: 英国
• 起止时间: 2009 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FG011362%2F1
• 关键词: competitive; dynamics; toxic; non; ribotypes

A number of species of marine phytoplankton produce natural biotoxins. Filter feeding shellfish ingest these phytoplankton without any apparent negative effects. However, bio-accumulation of the toxins in the shellfish flesh allows concentrations to reach sufficiency elevated levels that serious health consequences may result for humans that ingest the shellfish. Owing to the severity and possible fatality of the symptoms, paralytic shellfish poisoning (PSP) is perhaps the globally most important shellfish poisoning syndrome. PSP is caused by potent neurotoxins (saxitoxins) produced by the dinoflagellate genus Alexandrium. PSP occurs worldwide, with toxicity of shellfish in UK waters being characterised by frequent low level toxicity (monitoring programs indicating 100's of occurrences annually) and sporadic major toxicity events. Blooms of the causative species vary both spatially and temporally, and as yet we have very little understanding of the environmental factors that govern them. Human health is safeguarded by government biotoxin and phytoplankton monitoring programmes operated by Food Safety Authorities at significant cost to the economy. Of the various species of Alexandrium, the species complex Alexandrium tamarense is of particular concern in UK waters. Non toxic, group III, A.tamarense have historically been found in France, Spain and Portugal with their northernmost extent being the south of the UK. In contrast, toxic cells of group I A.tamarense are characteristic of northerly latitudes. However, recent studies have indicated changing distributions, with the non toxic group III cells now being found as far north as Shetland. Waters around the UK are known to be warming, suggesting that this, or other associated environmental changes (e.g. localised salinity, pH or light conditions), have allowed group III cells to 'invade' northern waters, where they now compete with group I. This is consistent with monitoring observations of reduced PSP events in recent years, but with no significant change in the total abundance of A.tamarense. Study of the factors driving the changing distributions of A.tamarense will provide better understanding and predictive ability of PSP events. This will allow more targeted biotoxin monitoring and better safeguard human health. Furthermore, such study will allow us to investigate how climate change is influencing the distribution of marine phytoplankton in UK waters. Recently we have isolated into laboratory culture strains of both group I and group III A.tamarense providing, for the first time, cultures of both toxic and non toxic strains of the organism from a single region. We shall study the influence of environmental conditions on strain growth and toxicity both individually and in competition. In addition, as A.tamarense forms an overwintering resting stage (a cyst) which settles to the sea floor and only germinates when conditions are favourable, we shall study the effect of environmental conditions on cyst germination. As both A.tamarense strains are of a single species, it is not possible to discriminate between them based on morphology. We will therefore utilise recently developed oligonucleotide probes for A.tamarense. After treatment with these molecular probes, and viewed under ultra violet light on a flourescence microscope, the non-toxic group III cells glow green and the toxic groups I cells glow gold, allowing for easy discrimination and enumeration even when cells are grown in combination to study their competition. Finally, we shall use our experimental results to derive and parameterise mathematical models for A.tamarense. These models will be used to simulate in situ data on the abundance of the different strains of A.tamarense we are currently collecting at a number of sites. Once developed, these models will increase our ability to predict the likelihood of a PSP event based on knowledge of the environmental conditions.

许多海洋浮游植物会产生天然生物毒素。过滤喂食贝类摄入这些浮游植物，没有任何明显的负面影响。然而，贝类肉体中毒素的生物蓄积使浓度可以达到足够的水平，从而使摄入贝类的人类可能导致严重的健康后果。由于症状的严重程度和可能的死亡，瘫痪贝类中毒（PSP）也许是全球最重要的贝类中毒综合征。 PSP是由Alexandrium鞭毛藻属产生的有效神经毒素（saxitoxins）引起的。 PSP发生在全球范围内，英国水域中贝类的毒性为特征，其特征是频繁的低水平毒性（监测表明每年发生100次发生的计划）和零星的重大毒性事件。因果关系的花朵在空间和时间上都不同，但我们对控制它们的环境因素的了解很少。食品安全当局运营的政府生物毒素和浮游植物监测计划为经济付出了巨大的代价，由政府生物毒素和浮游植物监测计划保护人类健康。在各种亚历山大种类中，在英国水域中，物种复杂的亚历山大tamarense特别关注。在法国，西班牙和葡萄牙历史上发现了无毒的III组，A.tamarense，其最北端是英国南部。相比之下，a a.tamarense的有毒细胞是北纬度的特征。然而，最近的研究表明分布发生了变化，现在发现非毒性组III细胞北部至设得兰群岛。众所周知，英国各地的水域正在变暖，这表明这种或其他相关的环境变化（例如局部盐度，pH或光条件）使III组细胞可以“入侵”北水域，现在它们与In组竞争。这与近年来PSP事件的监测观察结果一致，但在A. Tamarensens brundance bundancarensemensens bundamarensens beclance bundamarensen beclance bundamarens in the PSP却没有显着变化。研究推动A.tamarense变化分布的因素将提供PSP事件的更好理解和预测能力。这将允许更多针对性的生物毒素监测并更好地保护人类健康。此外，此类研究将使我们能够研究气候变化如何影响英国水域海洋浮游植物的分布。最近，我们已经分离成I组和III组的实验室培养菌株，这首先提供了来自单个区域的有机体和非毒性菌株的培养物。我们将研究环境条件对分别和竞争中应变生长和毒性的影响。此外，由于A.tamarense形成了一个越冬的静息阶段（囊肿），该阶段（囊肿）沉降到海底，只有在条件良好的情况下才会发芽，我们将研究环境条件对囊肿发芽的影响。由于两种a.tamarense菌株都是一个单一的物种，因此不可能根据形态区分它们。因此，我们将利用最近开发的寡核苷酸探针进行A.tamarense。用这些分子探针处理后，并在粉料显微镜上观察到在超紫罗兰色的光线下，无毒组III细胞发光绿色和有毒基团I细胞发光，即使在组合结合生长细胞以研究其竞争中，也可以轻松辨别和枚举。最后，我们将使用我们的实验结果来得出A.tamarense的数学模型。这些模型将用于模拟我们目前在许多站点收集的a.tamarense菌株的丰度的原位数据。一旦开发，这些模型将提高我们根据对环境条件的知识来预测PSP事件的可能性的能力。