The fate of diatoms in future acidified oceans could have dramatic implications on marine ecosystems, because they account for ~40% of marine primary production. Here, we quantify resilience of
- Award ID(s):
- 2050550
- NSF-PAR ID:
- 10329527
- Date Published:
- Journal Name:
- Frontiers in Marine Science
- Volume:
- 8
- ISSN:
- 2296-7745
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract Thalassiosira pseudonana in mid-20th century (300 ppm CO2) and future (1000 ppm CO2) conditions that cause ocean acidification, using a stress test that probes its ability to recover from incrementally higher amount of low-dose ultraviolet A (UVA) and B (UVB) radiation and re-initiate growth in day–night cycles, limited by nitrogen. While all cultures eventually collapse, those growing at 300 ppm CO2succumb sooner. The underlying mechanism for collapse appears to be a system failure resulting from “loss of relational resilience,” that is, inability to adopt physiological states matched to N-availability and phase of the diurnal cycle. Importantly, under elevated CO2conditions diatoms sustain relational resilience over a longer timeframe, demonstrating increased resilience to future acidified ocean conditions. This stress test framework can be extended to evaluate and predict how various climate change associated stressors may impact microbial community resilience. -
High‐affinity nitrate transporters are considered to be the major transporter system for nitrate uptake in diatoms. In the diatom genus
Skeletonema , three forms of genes encoding high‐affinity nitrate transporters ( ) were newly identified from transcriptomes generated as part of the marine microbial eukaryote transcriptome sequencing project. To examine the expression of each form ofNRT 2 under different nitrogen environments, laboratory experiments were conducted under nitrate‐sufficient, ammonium‐sufficient, and nitrate‐limited conditions using three ecologically importantNRT 2Skeletonema species:S. dohrnii ,S. menzelii, andS. marinoi . Primers were developed for each form and species and Q‐NRT 2RT ‐PCR was performed. For each form, the threeNRT 2Skeletonema species had similar transcriptional patterns. The transcript levels of were significantly elevated under nitrogen‐limited conditions, but strongly repressed in the presence of ammonium. The transcript levels ofNRT 2:1 were also repressed by ammonium, but increased 5‐ to 10‐fold under nitrate‐sufficient and nitrogen‐limited conditions. Finally, the transcript levels ofNRT 2:2 did not vary significantly under various nitrogen conditions, and behaved more like a constitutively expressed gene. Based on the observed transcript variation amongNRT 2:3 forms, we propose a revised model describing nitrate uptake kinetics regulated by multiple forms of nitrate transporter genes in response to various nitrogen conditions inNRT 2Skeletonema . The differential transcriptional responses among species suggest that species‐specific adaptive strategies exist within this genus to cope with environmental changes.NRT 2 -
Summary The post‐transcriptional regulation involved in the responses of diatoms to silicon is poorly understood. Using a poly(A)‐tag sequencing (
PAT ‐seq) technique that interrogates only the junctions of 3′‐untranslated region (UTR) and the poly(A) tails at the transcriptome level, a comprehensive comparison of alternative polyadenylation (APA ) was performed to understand the role of post‐transcriptional regulation in various silicon‐related cellular responses for the marine diatomThalassiosira pseudonana . In total, 23 701 poly(A) clusters and 6894APA genes, treated with silicon starvation and replenishment, were identified at nine time points. SignificantAPA was found in numerous genes (e.g. five cingulin genes) closely associated with the silicon‐starvation response, girdle bands and valve synthesis, suggesting that many genes participated in the responses to silicon availability and biosilica formation through changes in transcript isoforms. The poly(A) site usage profiles were distinct during various stages of silicon biomineralization responses. Moreover, a correlation betweenAPA and expression levels ofAPA switching genes was also discovered. This is an interesting study that presents a genome‐wide profile of transcript ends in diatoms, which is distinct from that of higher plants, animals and other microalgae. This work provides an important resource to understand a different aspect of cell‐wall synthesis. -
High‐affinity nitrate transporters are considered to be the major transporter system for nitrate uptake in diatoms. In the diatom genus Skeletonema, three forms of genes encoding high‐affinity nitrate transporters (NRT2) were newly identified from transcriptomes generated as part of the marine microbial eukaryote transcriptome sequencing project. To examine the expression of each form of NRT2 under different nitrogen environments, laboratory experiments were conducted under nitrate‐sufficient, ammonium‐sufficient, and nitrate‐limited conditions using three ecologically important Skeletonema species: S. dohrnii, S. menzelii, and S. marinoi. Primers were developed for each NRT2 form and species and Q‐RT‐PCR was performed. For each NRT2 form, the three Skeletonema species had similar transcriptional patterns. The transcript levels of NRT2:1 were significantly elevated under nitrogen‐limited conditions, but strongly repressed in the presence of ammonium. The transcript levels of NRT2:2 were also repressed by ammonium, but increased 5‐ to 10‐fold under nitrate‐sufficient and nitrogen‐limited conditions. Finally, the transcript levels of NRT2:3 did not vary significantly under various nitrogen conditions, and behaved more like a constitutively expressed gene. Based on the observed transcript variation among NRT2 forms, we propose a revised model describing nitrate uptake kinetics regulated by multiple forms of nitrate transporter genes in response to various nitrogen conditions in Skeletonema. The differential NRT2 transcriptional responses among species suggest that species‐specific adaptive strategies exist within this genus to cope with environmental changes.more » « less
-
Abstract The importance of zinc (Zn) as a nutrient and its ability to be substituted for by cobalt (Co) have been characterized in model marine diatoms. However, the extent to which this substitution capability is distributed among diatom taxa is unknown. Zn/Co metabolic substitution was assayed in four diatom species as measured by the effect of free ion concentrations of Zn2+and Co2+on specific growth rate. Analysis of growth responses found substitution of these metals can occur within the northwest Atlantic isolate
Thalassiosira pseudonana CCMP1335, the northeast Atlantic isolatePhaeodactylum tricornutum CCMP632, and within the northeast Pacific isolatesPseudo‐nitzschia delicatissima UNC1205 andThalassiosira sp. UNC1203. Metabolic substitution of Co in place of Zn in the Atlantic diatoms supports their growth in media lacking added Zn, but at the cost of reduced growth rates. In contrast, highly efficient Zn/Co substitution that supported growth even in media lacking added Zn was observed in the northeast Pacific diatoms. We also present new data from the northeast Pacific Line P transect that revealed dissolved Co and Zn ratios (dCo : dZn) as high as 3.52 : 1 at surface (0–100 m) depths. We posit that the enhanced ability of the NE Pacific diatoms to grow using Co is an adaptation to these high surface dCo : dZn ratios. Particulate metal data and single‐cell metal quotas also suggest a high Zn demand in diatoms that may be partially compensated for by Co.