Department of Biology, Aquatic Ecology, Lund University, Sweden; Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Sweden.
Department of Biology, Aquatic Ecology, Lund University, Sweden.
Harmful Algae. 2016 Jun;56:67-76. doi: 10.1016/j.hal.2016.04.012. Epub 2016 May 25.
A number of marine and freshwater harmful algal bloom (HAB) species have colonized new areas and expanded their habitat range in recent years. Nevertheless it is notoriously difficult to establish when colonization first occurred, what the dispersal routes are, and to separate recent invasion from increases in existent but small populations. The freshwater raphidophyte Gonyostomum semen is a nuisance species that has expanded its habitat range and increased in abundance in northern Europe during the past decades. To evaluate to what extent sediments can be used for determining historic occurrence of G. semen, a quantitative real-time PCR method for detecting cysts of this algae was developed. This paper presents a qPCR protocol with a set of primers that are specific to Gonyostomum and with PCR conditions optimized for sediment samples from humic lakes, which are the common habitat of G. semen. With this sensitive method as few as 1.6 cysts per PCR reaction could be reliably quantified, corresponding to 320 cysts per g wet weight sediment. Cysts were present in sediments with ages ranging from years to decades and their persistence allows detection of historic populations up to at least 50 years old. With this qPCR assay it will be possible to trace the presence of G. semen in environments prior to the onset of algae-specific monitoring programs as well as for quantification in water column samples.
近年来，一些海洋和淡水有害藻华（HAB）物种已经在新的地区定居，并扩大了它们的栖息地范围。然而，要确定首次定居的时间、扩散途径，以及将最近的入侵与现存但数量较少的种群的增加区分开来，这是非常困难的。淡水甲藻 Gonystomum semen 是一种有害物种，它在过去几十年中已经扩大了其栖息地范围，并在北欧地区的数量增加。为了评估沉积物在确定 Gonystomum semen 的历史存在方面可以起到多大作用，开发了一种用于检测该藻类包囊的定量实时 PCR 方法。本文提出了一种 qPCR 方案，该方案使用了一组针对 Gonystomum 的特异性引物，并对腐殖质湖泊（Gonystomum semen 的常见栖息地）的沉积物样品进行了优化的 PCR 条件。使用这种敏感的方法，可以可靠地定量低至每 PCR 反应 1.6 个包囊，相当于每克湿重沉积物 320 个包囊。在年龄从数年到数十年的沉积物中存在包囊，其持久性允许检测到至少 50 年前的历史种群。通过这种 qPCR 检测方法，可以追踪 Gonystomum semen 在藻类特异性监测计划开始之前的存在情况，以及在水柱样品中的定量检测。
