Effect of light and prey availability on gene expression of the mixotrophic chrysophyte, Ochromonas sp.
Effect of light and prey availability on gene expression of the mixotrophic chrysophyte, Ochromonas sp.
复制标题
DOI：
10.1186/s12864-017-3549-1
复制
发表时间：
2017-02-14
期刊：
影响因子：
4.4
通讯作者：
Caron DA
中科院分区：
文献类型：
--
作者：
Lie AA;Liu Z;Terrado R;Tatters AO;Heidelberg KB;Caron DA
Ochromonas 是混合营养型金藻植物的一个属，在许多水生环境中普遍存在。该属的物种可能是细菌的重要消费者，但其进行光合作用的能力各不相同。我们研究了光和细菌对主要吞噬型 Ochromonas 物种的生长和基因表达的影响。 Ochromonas sp 的无菌培养物。用热灭活细菌（HKB）喂养并在恒定光照或黑暗中生长。在存在 HKB 的光照或黑暗条件下（Light + HKB；Dark + HKB）以及 HKB 耗尽后的光照条件下（Light + 耗尽 HKB）从培养物中提取 RNA。在光照或黑暗条件下生长的藻类之间的生长或细菌摄入率没有显着差异。光的可用性导致转录组中仅 8% 的基因出现差异表达。与 Dark + HKB 处理相比，Light + HKB 处理中与光合作用、吞噬作用和四吡咯合成相关的许多基因上调。相反，Light + HKB和Light + 耗尽HKB处理之间的比较表明，HKB的存在导致59%的基因差异表达，包括涉及主要碳和氮代谢途径的大多数基因。 HKB 存在时，编码利用葡萄糖的单向酶的基因上调，这意味着吞噬过程中糖酵解活性增加。没有 HKB 的藻类上调了编码铵转运蛋白的基因表达，这意味着当猎物无法获得时，它们会从培养基中吸收无机氮。转录组结果与之前的观察一致，即光对 Ochromonas sp. 种群生长的影响极小。然而，光导致许多光养和吞噬相关基因的上调，而细菌猎物的可用性导致主要碳和氮代谢途径的显着变化。我们的研究证明了转录组学方法在提高我们对复杂混合营养生物的营养生理学的理解方面的潜力，并揭示了 Ochromonas sp. 的反应。从传统文化研究中看不出来。本文的在线版本 (doi:10.1186/s12864-017-3549-1) 包含补充材料，可供授权用户使用。
Ochromonas is a genus of mixotrophic chrysophytes that is found ubiquitously in many aquatic environments. Species in this genus can be important consumers of bacteria but vary in their ability to perform photosynthesis. We studied the effect of light and bacteria on growth and gene expression of a predominantly phagotrophic Ochromonas species. Axenic cultures of Ochromonas sp. were fed with heat-killed bacteria (HKB) and grown in constant light or darkness. RNA was extracted from cultures in the light or in the dark with HKB present (Light + HKB; Dark + HKB), and in the light after HKB were depleted (Light + depleted HKB). There were no significant differences in the growth or bacterial ingestion rates between algae grown in light or dark conditions. The availability of light led to a differential expression of only 8% of genes in the transcriptome. A number of genes associated with photosynthesis, phagotrophy, and tetrapyrrole synthesis was upregulated in the Light + HKB treatment compared to Dark + HKB. Conversely, the comparison between the Light + HKB and Light + depleted HKB treatments revealed that the presence of HKB led to differential expression of 59% of genes, including the majority of genes involved in major carbon and nitrogen metabolic pathways. Genes coding for unidirectional enzymes for the utilization of glucose were upregulated in the presence of HKB, implying increased glycolytic activities during phagotrophy. Algae without HKB upregulated their expression of genes coding for ammonium transporters, implying uptake of inorganic nitrogen from the culture medium when prey were unavailable. Transcriptomic results agreed with previous observations that light had minimal effect on the population growth of Ochromonas sp. However, light led to the upregulation of a number of phototrophy- and phagotrophy-related genes, while the availability of bacterial prey led to prominent changes in major carbon and nitrogen metabolic pathways. Our study demonstrated the potential of transcriptomic approaches to improve our understanding of the trophic physiologies of complex mixotrophs, and revealed responses in Ochromonas sp. not apparent from traditional culture studies. The online version of this article (doi:10.1186/s12864-017-3549-1) contains supplementary material, which is available to authorized users.