Grazing-activated chemical defence in a unicellular marine alga

The understanding of deep chlorophyll layers (DCLs) in the Great Lakes—largely reported as a mix of picoplankton and mixotrophic nanoflagellates—is predominantly based on studies of deep (>30 m), offshore locations. Here, we document and characterize nearshore DCLs from two meso-oligotrophic embayments, Twelve Mile Bay (TMB) and South Bay (SB), along eastern Georgian Bay, Lake Huron (Ontario, Canada) in 2014, 2015, and 2018. Both embayments showed the annual formation of DCLs, present as dense, thin, metalimnetic plates dominated by the large, potentially toxic, and bloom-forming cyanobacteria Planktothrix cf. isothrix. The contribution of P. cf. isothrix to the deep-living total biomass (TB) increased as thermal stratification progressed over the ice-free season, reaching 40% in TMB (0.6 mg/L at 9.5 m) and 65% in South Bay (3.5 mg/L at 7.5 m) in 2015. The euphotic zone in each embayment extended down past the mixed layer, into the nutrient-enriched hypoxic hypolimnia, consistent with other studies of similar systems with DCLs. The co-occurrence of the metal-oxidizing bacteria Leptothrix spp. and bactivorous flagellates within the metalimnetic DCLs suggests that the microbial loop plays an important role in recycling nutrients within these layers, particularly phosphate (PO4) and iron (Fe). Samples taken through the water column in both embayments showed measurable concentrations of the cyanobacterial toxins microcystins (max. 0.4 µg/L) and the other bioactive metabolites anabaenopeptins (max. ~7 µg/L) and cyanopeptolins (max. 1 ng/L), along with the corresponding genes (max. in 2018). These oligopeptides are known to act as metabolic inhibitors (e.g., in chemical defence against grazers, parasites) and allow a competitive advantage. In TMB, the 2018 peaks in these oligopeptides and genes coincided with the P. cf. isothrix DCLs, suggesting this species as the main source. Our data indicate that intersecting physicochemical gradients of light and nutrient-enriched hypoxic hypolimnia are key factors in supporting DCLs in TMB and SB. Microbial activity and allelopathy may also influence DCL community structure and function, and require further investigation, particularly related to the dominance of potentially toxigenic species such as P. cf. isothrix.

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A PEPTIDE FROM A MARINE ALGA

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)56595-9 ◽

1949 ◽

Vol 181 (2) ◽

pp. 719-729

Author(s):

Charles A. Dekker ◽

David. Stone ◽

Joseph S. Fruton

Keyword(s):

Marine Alga

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Integrative analysis of chloroplast DNA methylation in a marine alga—Saccharina japonica

Plant Molecular Biology ◽

10.1007/s11103-020-01113-9 ◽

2021 ◽

Author(s):

Linhong Teng ◽

Wentao Han ◽

Xiao Fan ◽

Xiaowen Zhang ◽

Dong Xu ◽

...

Keyword(s):

Dna Methylation ◽

Chloroplast Dna ◽

Marine Alga ◽

Saccharina Japonica ◽

Integrative Analysis

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Growing up aspen: ontogeny and trade-offs shape growth, defence and reproduction in a foundation species

Annals of Botany ◽

10.1093/aob/mcaa070 ◽

2020 ◽

Author(s):

Christopher T Cole ◽

Clay J Morrow ◽

Hilary L Barker ◽

Kennedy F Rubert-Nason ◽

Jennifer F L Riehl ◽

...

Keyword(s):

Intraspecific Variation ◽

Genotypic Variation ◽

Chemical Defence ◽

Extrafloral Nectaries ◽

Foundation Species ◽

Community Genetics ◽

Indirect Defence ◽

Juvenile Period ◽

Trade Offs ◽

Sex Marker

Abstract Background and Aims Intraspecific variation in foundation species of forest ecosystems can shape community and ecosystem properties, particularly when that variation has a genetic basis. Traits mediating interactions with other species are predicted by simple allocation models to follow ontogenetic patterns that are rarely studied in trees. The aim of this research was to identify the roles of genotype, ontogeny and genotypic trade-offs shaping growth, defence and reproduction in aspen. Methods We established a common garden replicating >500 aspen genets in Wisconsin, USA. Trees were measured through the juvenile period into the onset of reproduction, for growth, defence chemistry (phenolic glycosides and condensed tannins), nitrogen, extrafloral nectaries, leaf morphology (specific leaf area), flower production and foliar herbivory and disease. We also assayed the TOZ19 sex marker and heterozygosity at ten microsatellite loci. Key Results We found high levels of genotypic variation for all traits, and high heritabilities for both the traits and their ontogenetic trajectories. Ontogeny strongly shaped intraspecific variation, and trade-offs among growth, defence and reproduction supported some predictions while contradicting others. Both direct resistance (chemical defence) and indirect defence (extrafloral nectaries) declined during the juvenile stage, prior to the onset of reproduction. Reproduction was higher in trees that were larger, male and had higher individual heterozygosity. Growth was diminished by genotypic allocation to both direct and indirect defence as well as to reproduction, but we found no evidence of trade-offs between defence and reproduction. Conclusions Key traits affecting the ecological communities of aspen have high levels of genotypic variation and heritability, strong patterns of ontogeny and clear trade-offs among growth, defence and reproduction. The architecture of aspen’s community genetics – its ontogeny, trade-offs and especially its great variability – is shaped by both its broad range and the diverse community of associates, and in turn further fosters that diversity.

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Brightly coloured tissues in limid bivalves chemically deter predators

Royal Society Open Science ◽

10.1098/rsos.191298 ◽

2019 ◽

Vol 6 (10) ◽

pp. 191298

Author(s):

Lindsey F. Dougherty ◽

Alexandria K. Niebergall ◽

Corey D. Broeckling ◽

Kevin L. Schauer ◽

Jingchun Li

Keyword(s):

Mass Spectrometry ◽

Chemical Defence ◽

Chemical Compositions ◽

Marine Bivalve ◽

Metabolomic Analysis ◽

Defence Mechanism ◽

Defensive Compounds ◽

Mantis Shrimp ◽

Metabolite Profiles ◽

Bivalve Tissues

Members of the marine bivalve family Limidae are known for their bright appearance. In this study, their colourful tissues were examined as a defence mechanism towards predators. We showed that when attacked by the peacock mantis shrimp ( Odontodactylus scyllarus ), the ‘disco’ clam, Ctenoides ales , opened wide to expose brightly coloured tissues to the predator. The predator also significantly preferred to consume the internal, non-colourful clam tissues than the external, colourful tissues. Mass spectrometry-based metabolomic analysis confirmed that colourful tissues had significantly different chemical compositions than the non-colourful ones. The internal, non-colourful tissues had metabolite profiles more similar to an outgroup bivalve than to the species' own colourful external tissues. A number of the compounds that differentiated the colourful tissues from the non-colourful tissues appeared to be peptide-like, which potentially serve as the underlying defensive compounds. This is the first study demonstrating that colourful bivalve tissues are used for chemical defence.

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Cold Steeping Infusion, a Novel Lectin Extraction Technique for the Isolation, Purification and Partial Characterization of Lectins from the Green Venezuelan Marine Alga Caulerpa serrulata

Natural Product Communications ◽

10.1177/1934578x1801301233 ◽

2018 ◽

Vol 13 (12) ◽

pp. 1934578X1801301

Author(s):

Pablo Djabayan-Djibeyan ◽

Brian Carpenter ◽

Gerardo Medina-Ramírez ◽

Felix Andueza-Leal ◽

Andrés León-Leal ◽

...

Keyword(s):

Molecular Weight ◽

Red Blood Cells ◽

Ammonium Sulfate ◽

Bioactive Compounds ◽

Blood Cells ◽

Marine Alga ◽

Continuous Production ◽

Isotonic Saline ◽

Size Exclusion ◽

Extraction Technique

A lectin from the green Venezuelan marine alga Caulerpa serrulata was extracted with phosphate buffered saline (PBS) using cold steeping infusion (CSI) and by grinding with liquid nitrogen (GLN). The proteins were precipitated using solid ammonium sulfate. Both the crude extracts and ammonium sulfate precipitated proteins were tested for hemagglutinins using native and papain-treated human red blood cell suspensions in isotonic saline solution. Purification of lectins was achieved using affinity chromatography-sugar-epoxy-sepharose 6B and molecular weight was assessed by size exclusion chromatography using Bio-gel® P-100 and SDS-PAGE with 2-mercaptoethanol. IEF-urea 8M was also evaluated. Using CSI it was shown that the marine alga released hemagglutinating compounds into the solutions; the same hemagglutinating compounds were also obtained by GLN. Ammonium sulfate precipitated proteins exhibited agglutinating activity against native and papain-treated human red blood cells. Temperature and EDTA were shown to affect dramatically the lectin activity towards red blood cells. A lectin was purified efficiently and the molecular weight calculated as approximately 78,000 Daltons. The CSI technique demonstrated that the alga could be returned to an active metabolic state by immersion in a simple buffer after having been kept dormant by freezing at −20°C for long periods. It was also shown that the alga was releasing bioactive compounds into the solutions and, therefore, this procedure is being suggested as a good, gentle, non-disruptive extraction technique and we postulate CSI as a possible bioreactor for the continuous production of bioactive compounds from green marine algae.

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