Functional adaptation of diatoms to environmental conditions in sea ice of the Southern Ocean

硅藻对南大洋海冰环境条件的功能适应

• 批准号: NE/I001751/1
• 负责人: Thomas Mock
• 金额: $ 4.9万
• 依托单位: University of East Anglia
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FI001751%2F1
• 关键词: Functional; adaptation; diatoms; environmental; conditions

In winter sea ice covers an area of up to 7% of the earth surface, which clearly as such is one of the largest biomes on earth. Sea ice can be thought of as a thin blanket covering the ocean surface, which controls, but is also controlled by fluxes of heat and moisture. The life cycles of many marine organisms ranging from bacteria, algae, small animals, whales and even humans are influenced by large-scale cycles of sea ice formation. Thus, sea ice is recognized as a fundamental component of the system earth, which is key for our predictions of future climate conditions as has become increasingly apparent in the last decade due to rapid global warming. The possible implications of a gradual loss of sea ice due to higher global temperatures are not fully understood yet but pictures of shrinking Arctic sea ice in summer has become the focus of media and increasing attention from the general public. Focus of this grant application are microalgae that live inside the porous matrix of sea ice. Most of them belong to the group of diatoms, which in general play a key role on earth because they are responsible for 25% of primary fixation of carbon dioxide, which is as much as all tropical rain forests combined. Why especially diatoms dominate sea ice algal communities is not fully understood yet but we know that they are virtually the sole source of fixed carbon for higher trophical levels in ice-covered waters. In fact, the short food chain diatom-krill-whale is depend on ice algae because they provide food for young krill when other sources of food in winter are lacking. This food chain might be severely influenced by a reduction of sea ice due to global warming. Despite the significance of polar sea ice algae virtually nothing is know about their fundamental biology. This is why the US Department of Energy (DOE) has selected one of the most important sea ice diatom species (Fragilariopsis cylindrus) to sequence its genome under the guidance of the applicant. The genome sequence is now available and has brought exciting new insights into life at and below the freezing point of sea water. For instance, the genome encodes a previously unknown family of antifreeze proteins. It also encodes genes that were not anticipated to be present in this genome such as a gene that encodes a protein from bacteria for harvesting light to generate ATP. It was not anticipated because F. cylindrus has chloroplasts in which photosynthesis like in higher plants generates ATP. Thus, the function of this gene is not known yet as for many other genes in the genome as well. One first step to shed light on the function of genes is to study their expression under different environmental conditions, which is one main goal of this proposal. We propose to conduct experiments where we treat the cells under conditions that are present in sea ice (e.g. freezing temperatures, nutrient limitation) and which are predicted outcomes of global warming in polar regions (e.g. elevated temperatures and carbon dioxide concentrations). We will then sequence the transcriptome with high-throughput sequencing technology to identify genes that are differentially expressed under our experimental conditions. Selected genes will be confirmed by quantitative qPCR. This study will help to identify the short term acclimation of F. cylindrus to sea ice as it forms every autumn. Adaptation to sea ice will be studied by comparative genome analysis between F. cylindrus and the close relative F. kerguelensis, which lives also in cold polar sea water but doesn't thrive in sea ice. This comparison will not only shed light on specific adaptation necessary for thriving in sea ice but also the predicted outcomes of global warming in polar oceans because ice free waters will more and more dominate these habitats. High-throughput sequencing will be used to sequence the genome of F. kerguelensis and large and small scale genome analysis will reveal the differences.

在冬季，海冰覆盖了地球表面的7%，这显然是地球上最大的生物群落之一。海冰可以被认为是覆盖在海洋表面的薄毯，它控制着，但也受到热量和水分通量的控制。许多海洋生物的生命周期，包括细菌、藻类、小动物、鲸鱼甚至人类，都受到海冰形成的大规模周期的影响。因此，海冰被认为是地球系统的基本组成部分，这是我们预测未来气候条件的关键，由于全球快速变暖，这一点在过去十年中变得越来越明显。由于全球气温升高，海冰逐渐减少的可能影响尚未完全了解，但夏季北极海冰萎缩的照片已成为媒体关注的焦点，并越来越受到公众的关注。这项拨款申请的重点是生活在海冰多孔基质中的微藻。它们中的大多数属于硅藻类，通常在地球上起着关键作用，因为它们负责25%的二氧化碳初级固定，这相当于所有热带雨林的总和。为什么特别是硅藻主宰海冰藻类群落还没有完全理解，但我们知道，他们实际上是唯一的固定碳的来源，为更高的营养水平在冰封的沃茨。事实上，短食物链的磷虾-鲸鱼依赖于冰藻，因为它们在冬季缺乏其他食物来源时为年幼的磷虾提供食物。由于全球变暖，海冰减少，这一食物链可能受到严重影响。尽管极地海冰藻类的重要性，但实际上对它们的基本生物学一无所知。这就是为什么美国能源部（DOE）选择了一种最重要的海冰硅藻物种（Fragilariopsis cylindrus），在申请人的指导下对其基因组进行测序。基因组序列现在已经可用，并带来了令人兴奋的新的见解，生活在和低于海水的冰点。例如，基因组编码了一个以前未知的抗冻蛋白家族。它还编码预期不存在于该基因组中的基因，例如编码来自细菌的蛋白质的基因，用于捕获光以产生ATP。这是没有预料到的，因为F。圆柱藻有叶绿体，在叶绿体中光合作用像高等植物一样产生ATP。因此，该基因的功能还不清楚，因为基因组中的许多其他基因也是如此。阐明基因功能的第一步是研究它们在不同环境条件下的表达，这是本提案的主要目标之一。我们建议进行实验，我们在海冰中存在的条件下（例如冷冻温度，营养限制）处理细胞，这些条件是极地地区全球变暖的预测结果（例如升高的温度和二氧化碳浓度）。然后，我们将使用高通量测序技术对转录组进行测序，以确定在我们的实验条件下差异表达的基因。将通过定量qPCR确认选定的基因。本研究将有助于确定F.每年秋天形成的海冰上。对海冰的适应性将通过F. cylindrus和近缘种F.凯尔盖龙也生活在寒冷的极地海水中，但在海冰中不会茁壮成长。这种比较不仅将揭示在海冰中繁荣所必需的特定适应，而且还将揭示全球变暖在极地海洋中的预测结果，因为无冰沃茨将越来越多地主宰这些栖息地。高通量测序将用于F. kerguelensis和大规模和小规模基因组分析将揭示差异。

项目成果

Global discovery and characterization of small non-coding RNAs in marine microalgae.

海洋微藻中小非编码 RNA 的全球发现和表征。

• DOI: 10.1186/1471-2164-15-697
• 发表时间: 2014-08-20
• 期刊: BMC genomics
• 影响因子: 4.4
• 作者: Lopez-Gomollon S;Beckers M;Rathjen T;Moxon S;Maumus F;Mohorianu I;Moulton V;Dalmay T;Mock T
• 通讯作者: Mock T

Evolutionary genomics of the cold-adapted diatom Fragilariopsis cylindrus

• DOI: 10.1038/nature20803
• 发表时间: 2017-01-26
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Mock, Thomas;Otillar, Robert P.;Grigoriev, Igor V.
• 通讯作者: Grigoriev, Igor V.

The Marine Microbial Eukaryote Transcriptome Sequencing Project (MMETSP): illuminating the functional diversity of eukaryotic life in the oceans through transcriptome sequencing.

• DOI: 10.1371/journal.pbio.1001889
• 发表时间: 2014-06
• 期刊: PLoS biology
• 影响因子: 9.8
• 作者: Keeling PJ;Burki F;Wilcox HM;Allam B;Allen EE;Amaral-Zettler LA;Armbrust EV;Archibald JM;Bharti AK;Bell CJ;Beszteri B;Bidle KD;Cameron CT;Campbell L;Caron DA;Cattolico RA;Collier JL;Coyne K;Davy SK;Deschamps P;Dyhrman ST;Edvardsen B;Gates RD;Gobler CJ;Greenwood SJ;Guida SM;Jacobi JL;Jakobsen KS;James ER;Jenkins B;John U;Johnson MD;Juhl AR;Kamp A;Katz LA;Kiene R;Kudryavtsev A;Leander BS;Lin S;Lovejoy C;Lynn D;Marchetti A;McManus G;Nedelcu AM;Menden-Deuer S;Miceli C;Mock T;Montresor M;Moran MA;Murray S;Nadathur G;Nagai S;Ngam PB;Palenik B;Pawlowski J;Petroni G;Piganeau G;Posewitz MC;Rengefors K;Romano G;Rumpho ME;Rynearson T;Schilling KB;Schroeder DC;Simpson AG;Slamovits CH;Smith DR;Smith GJ;Smith SR;Sosik HM;Stief P;Theriot E;Twary SN;Umale PE;Vaulot D;Wawrik B;Wheeler GL;Wilson WH;Xu Y;Zingone A;Worden AZ
• 通讯作者: Worden AZ

Polar Microalgae: New Approaches towards Understanding Adaptations to an Extreme and Changing Environment.

• DOI: 10.3390/biology3010056
• 发表时间: 2014-01-28
• 期刊: Biology
• 影响因子: 4.2
• 作者: Lyon BR;Mock T
• 通讯作者: Mock T