Using quantitative real-time PCR to study competition and community dynamics among Delaware Inland Bays harmful algae in field and laboratory studies

Handy, Sara M.; Demir, Elif; Hutchins, David A.; Portune, Kevin J.; Whereat, Edward B.; Hare, Clint E.; Rose, Julie M.; Warner, Mark E.; Farestad, Muns; Cary, S. Craig; Coyne, Kathryn J.

doi:10.1016/j.hal.2007.12.018

Cited by 64 publications

(39 citation statements)

References 66 publications

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“…These species inhabit coastal estuarine environments where nitrogen availability can fluctuate widely (c.f. Handy et al 2008). Both species have also been shown to produce high concentrations of extracellular and intracellular NO (Zhang et al 2006;Kim et al 2008) during normal cell growth which may represent a significant loss of nitrogen to these species in an environment where nitrogen is limiting.…”

Section: Discussionmentioning

confidence: 99%

Analysis of raphidophyte assimilatory nitrate reductase reveals unique domain architecture incorporating a 2/2 hemoglobin

Stewart

Coyne

2011

Plant Mol Biol

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Eukaryotic assimilatory nitrate reductase (NR) is a multi-domain protein that catalyzes the rate-limiting step in nitrate assimilation. This protein is highly conserved and has been extensively characterized in plants and algae. Here, we report hybrid NRs (NR2-2/2HbN) identified in two microalgal species, Heterosigma akashiwo and Chattonella subsalsa, with a 2/2 hemoglobin (2/2Hb) inserted into the hinge 2 region of a prototypical NR. 2/2Hbs are a class of single-domain heme proteins found in bacteria, ciliates, algae and plants. Sequence analysis indicates that the C-terminal FAD/NADH reductase domain of NR2-2/2HbN retains identity with eukaryotic NR, suggesting that the 2/2Hb domain was inserted interior to the existing NR domain architecture. Phylogenetic analysis supports the placement of the 2/2Hb domain of NR2-2/2HbN within group I (N-type) 2/2Hbs with high similarity to mycobacterial 2/2HbNs, known to convert nitric oxide to nitrate. Experimental data confirms that H. akashiwo is capable of metabolizing nitric oxide and shows that HaNR2-2/2HbN expression increases in response to nitric oxide addition. Here, we propose a mechanism for the dual function of NR2-2/2HbN in which nitrate reduction and nitric oxide dioxygenase reactions are cooperative, such that conversion of nitric oxide to nitrate is followed by reduction of nitrate for assimilation as cellular nitrogen.

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Section: Discussionmentioning

confidence: 99%

Analysis of raphidophyte assimilatory nitrate reductase reveals unique domain architecture incorporating a 2/2 hemoglobin

Stewart

Coyne

2011

Plant Mol Biol

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“…Eutrophication of Delaware's inland bays (DIB), which consist of Rehoboth Bay, Indian River Bay, and Little Assawoman Bay, has increased over the last several decades, with high concentrations of nutrient inputs from agricultural and urban sources (16,17). Several harmful or potentially harmful algal bloom species (HABs) have been identified in DIB, and blooms of harmful algal species occur frequently (18). Among these are several species of harmful dinoflagellates, including Gyrodinium instriatum (19), Karlodinium veneficum (19), and Prorocentrum minimum (20), as well as raphidophytes, a group of species distributed globally in temperate coastal waters and freshwater environments.…”

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confidence: 99%

Community-Level and Species-Specific Associations between Phytoplankton and Particle-Associated Vibrio Species in Delaware's Inland Bays

Main

Salvitti

Whereat

et al. 2015

Appl Environ Microbiol

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Vibrio species are an abundant and diverse group of bacteria that form associations with phytoplankton. Correlations between Vibrio and phytoplankton abundance have been noted, suggesting that growth is enhanced during algal blooms or that association with phytoplankton provides a refuge from predation. Here, we investigated relationships between particle-associated Vibrio spp. and phytoplankton in Delaware's inland bays (DIB). The relative abundances of particle-associated Vibrio spp. and algal classes that form blooms in DIB (dinoflagellates, diatoms, and raphidophytes) were determined using quantitative PCR. The results demonstrated a significant correlation between particle-associated Vibrio abundance and phytoplankton, with higher correlations to diatoms and raphidophytes than to dinoflagellates. Species-specific associations were examined during a mixed bloom of Heterosigma akashiwo and Fibrocapsa japonica (Raphidophyceae) and indicated a significant positive correlation for particle-associated Vibrio abundance with H. akashiwo but a negative correlation with F. japonica. Changes in Vibrio assemblages during the bloom were evaluated using automated ribosomal intergenic spacer analysis (ARISA), which revealed significant differences between each size fraction but no significant change in Vibrio assemblages over the course of the bloom. Microzooplankton grazing experiments showed that losses of particle-associated Vibrio spp. may be offset by increased growth in the Vibrio population. Moreover, analysis of Vibrio assemblages by ARISA also indicated an increase in the relative abundance for specific members of the Vibrio community despite higher grazing pressure on the particle-associated population as a whole. The results of this investigation demonstrate links between phytoplankton and Vibrio that may lead to predictions of potential health risks and inform future management practices in this region. Bacteria within the genus Vibrio are naturally abundant in marine and estuarine environments (1), where they exhibit two alternative growth strategies: (i) association with particles as a biofilm or (ii) as free-living bacterioplankton (2). Association with planktonic organisms plays an important role in the ecology of Vibrio (3) by providing an enriched microenvironment for Vibrio spp. (4-6). Previous research demonstrated that planktonic copepods, in particular, enhance the survival and distribution of Vibrio in temperate and tropical areas (7,8). Associations with plankton may also provide a refuge from grazing by bacterivorous protozoa (9, 10), which can be substantial in some areas (11). Matz et al. (9), for example, showed that the cell density of Vibrio cholerae within a biofilm remained stable in the presence of protozoa, whereas planktonic cells were rapidly eliminated. However, particle association may not always be advantageous, as it may subject the cells to sinking forces or losses through "collateral damage" when host cells are preyed upon (10).In addition to copepods, Vibrio spp. also form attach...

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“…Smayda (1998) noted that the raphidophyte suite of Heterosigma, Fibrocapsa, and Chattonella often co-occur, and speculated that a global niche may be opening up for this HAB group. Interestingly, the same raphidophyte taxa also appeared beginning in 2000 in the Delaware Bays (Bourdelais et al, 2002;Handy et al, 2008). The ultimate source of these new HAB taxa in Georgia and South Carolina estuaries is enigmatic, but it may be significant that the shipping port of Savannah, which lies on the Savannah River bordering the two states, is one of the top five container ports in the USA (http://www.logisticsatlanta.com/marine.asp) and the largest USA South Atlantic gateway for Asian cargo (http:// www.shippingdigest.com/portinformation/portinformation.asp).…”

Section: Discussionmentioning

confidence: 87%

Expansion of potentially harmful algal taxa in a Georgia Estuary (USA)

Verity

2010

Harmful Algae

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Using quantitative real-time PCR to study competition and community dynamics among Delaware Inland Bays harmful algae in field and laboratory studies

Cited by 64 publications

References 66 publications

Analysis of raphidophyte assimilatory nitrate reductase reveals unique domain architecture incorporating a 2/2 hemoglobin

Analysis of raphidophyte assimilatory nitrate reductase reveals unique domain architecture incorporating a 2/2 hemoglobin

Community-Level and Species-Specific Associations between Phytoplankton and Particle-Associated Vibrio Species in Delaware's Inland Bays

Expansion of potentially harmful algal taxa in a Georgia Estuary (USA)

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