'N vergelykende studie van vismeel, sonneblomoliekoekmeel en formaldehiedbehandelde sonneblomoliekoekmeel as proteïen supplemente vir skape

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Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics

Harmful algal blooms (HABs) cause significant economic and ecological damage worldwide. Despite considerable efforts, a comprehensive understanding of the factors that promote these blooms has been lacking, because the biochemical pathways that facilitate their dominance relative to other phytoplankton within specific environments have not been identified. Here, biogeochemical measurements showed that the harmful alga Aureococcus anophagefferens outcompeted co-occurring phytoplankton in estuaries with elevated levels of dissolved organic matter and turbidity and low levels of dissolved inorganic nitrogen. We subsequently sequenced the genome of A. anophagefferens and compared its gene complement with those of six competing phytoplankton species identified through metaproteomics. Using an ecogenomic approach, we specifically focused on gene sets that may facilitate dominance within the environmental conditions present during blooms. A. anophagefferens possesses a larger genome (56 Mbp) and has more genes involved in light harvesting, organic carbon and nitrogen use, and encoding selenium- and metal-requiring enzymes than competing phytoplankton. Genes for the synthesis of microbial deterrents likely permit the proliferation of this species, with reduced mortality losses during blooms. Collectively, these findings suggest that anthropogenic activities resulting in elevated levels of turbidity, organic matter, and metals have opened a niche within coastal ecosystems that ideally suits the unique genetic capacity of A. anophagefferens and thus, has facilitated the proliferation of this and potentially other HABs

Peptide Hydrolysis, Amino Acid Oxidation, and Nitrogen Uptake in Communities Seasonally Dominated by Aureococcus Anophagefferens

Elevated levels of dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) are among the factors implicated in the initiation of algal blooms. However, the degree to which phytoplankton augment their autotrophic metabolism with heterotrophic uptake of organic carbon that is associated with DON is unknown. We evaluated the relative importance of peptide hydrolysis, amino acid oxidation, and amino acid uptake over a seasonal cycle in an embayment on Long Island, New York, that had high concentrations of dissolved organic matter (DOM) and a bloom of the brown tide pelagophyte, Aureococcus anophagefferens. Amino acids were a significant component (up to 50%) of the total N uptake, particularly during the late summer. About half of the associated amino acid C was also taken up. Amino acid oxidation rates were an order of magnitude lower than free amino acid uptake rates, but still supplied up to 32.5% of the NH4+ taken up. Up to 75% of the amino acid oxidation was in the bacterial size fraction (\u3c1.2 μm), and rates were significantly correlated with bacterial densities. Peptide hydrolysis rates were high, and most (up to 72%) occurred in the brown tide size fraction (1.2–5 μm). The high rates of peptide hydrolysis and amino acid uptake measured in cultures of A. anophagefferens confirm that this species can readily hydrolyze peptides and take up N and C from amino acids. Laboratory findings and size-fractionation studies in the field suggest that A. anophagefferens plays a major role in consumption of both C and N from DOM

Cooling of a gram-scale cantilever flexure to 70 mK with a servo-modified optical spring

A series of recent articles have presented results demonstrating optical cooling of macroscopic objects, highlighting the importance of this phenomenon for investigations of macroscopic quantum mechanics and its implications for thermal noise in gravitational wave detectors. In this Letter, we present a measurement of the off-resonance suspension thermal noise of a 1 g oscillator, and we show that it can be cooled to just 70 mK. The cooling is achieved by using a servo to impose a phase delay between oscillator motion and optical force. A model is developed to show how optical rigidity and optical cooling can be interchangeable using this technique

De novo assembly of Aureococcus anophagefferens transcriptomes reveals diverse responses to the low nutrient and low light conditions present during blooms

Transcriptome profiling was performed on the harmful algal bloom-forming pelagophyte Aureococcus anophagefferens strain CCMP 1850 to assess responses to common stressors for dense phytoplankton blooms: low inorganic nitrogen concentrations, low inorganic phosphorus concentrations, low light levels, and a replete control. The de novo assemblies of pooled reads from all treatments reconstructed ~54,000 transcripts using Trinity, and ~31,000 transcripts using ABySS. Comparison to the strain CCMP 1984 genome showed that the majority of the gene models were present in both de novo assemblies and that roughly 95% of contigs from both assemblies mapped to the genome, with Trinity capturing slightly more genome content. Sequence reads were mapped back to the de novo assemblies as well as the gene models and differential expression was analyzed using a Bayesian approach called Analysis of Sequence Counts (ASC). On average, 93% of significantly upregulated transcripts recovered by genome mapping were present in the significantly upregulated pool from both de novo assembly methods. Transcripts related to the transport and metabolism of nitrogen were upregulated in the low nitrogen treatment, transcripts encoding enzymes that hydrolyze organic phosphorus or relieve arsenic toxicity were upregulated in the low phosphorus treatment, and transcripts for enzymes that catabolize organic compounds, restructure lipid membranes, or are involved in sulfolipid biosynthesis were upregulated in the low light treatment. A comparison of this transcriptome to the nutrient regulated transcriptional response of CCMP 1984 identified conserved responses between these two strains. These analyses reveal the transcriptional underpinnings of physiological shifts that could contribute to the ecological success of this species in situ: organic matter processing, metal detoxification, lipid restructuring, and photosynthetic apparatus turnover

A novel immunofluorescence flow cytometry technique detects the expansion of brown tides caused by Aureoumbra lagunensis to the Caribbean Sea

Author Posting. © American Society for Microbiology, 2014. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Applied and Environmental Microbiology 80 (2014): 4947-4957, doi:10.1128/AEM.00888-14.During the past 3 decades, brown tides caused by the pelagophytes Aureococcus anophagefferens and Aureoumbra lagunensis have caused ecological and economic damage to coastal ecosystems across the globe. While blooms of A. lagunensis had previously been confined to Texas, in 2012, an expansive brown tide occurred on Florida's East Coast, causing widespread disruption within the Indian River and Mosquito Lagoons and generating renewed interest in this organism. A major impediment to detailed investigations of A. lagunensis in an ecosystem setting has been the absence of a rapid and reliable method for cell quantification. The combination of their small size (3 to 5 μm) and nondescript extracellular features makes identification and enumeration of these cells with conventional methods a challenge. Here we report the development of an immunological-based flow cytometry method that uses a fluorescently labeled antibody developed against A. lagunensis. This method is species specific, sensitive (detection limit of 1.5 × 103 cells ml−1), precise (1% relative standard deviation of replicated samples), and accurate (108% ± 8% recovery of spiked samples) over a wide range of cell concentrations. Furthermore, this method effectively quantifies A. lagunensis in both glutaraldehyde- and formalin-preserved samples, yields a high throughput of samples (∼35 samples h−1), and is cost-effective, making it an ideal tool for managers and scientists. This method successfully documented the recurrence of a brown tide bloom in Florida in 2013. Bloom densities were highest in June (>2.0 × 106 cells ml−1) and spanned >60 km from the Ponce de Leon inlet in the northern Mosquito Lagoon south to Titusville in the Indian River Lagoon. Low levels of A. lagunensis cells were found >250 km south of this region. This method also quickly and accurately identified A. lagunensis as the causative agent of a 2013 brown tide bloom in Guantanamo Bay, Cuba, and thus should prove useful for both quantifying the dynamics of ongoing blooms of A. lagunensis as well as documenting new outbreaks of this harmful alga.This research was funded as part of an NOAA ECOHAB Event Response grant to C.J.G. Support for D.M.A. was provided by the Woods Hole Center for Oceans and Human Health, a National Science Foundation grant (OCE-1314642), and a National Institute of Environmental Health Sciences grant (1-P01-ES021923-01)

Marine harmful algal blooms (HABs) in the United States: History, current status and future trends

Harmful algal blooms (HABs) are diverse phenomena involving multiple. species and classes of algae that occupy a broad range of habitats from lakes to oceans and produce a multiplicity of toxins or bioactive compounds that impact many different resources. Here, a review of the status of this complex array of marine HAB problems in the U.S. is presented, providing historical information and trends as well as future perspectives. The study relies on thirty years (1990–2019) of data in HAEDAT - the IOC-ICES-PICES Harmful Algal Event database, but also includes many other reports. At a qualitative level, the U.S. national HAB problem is far more extensive than was the case decades ago, with more toxic species and toxins to monitor, as well as a larger range of impacted resources and areas affected. (...

Short- and long-term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations

While larval bivalves are highly sensitive to ocean acidification, the basis for this sensitivity and the longer-term implications of this sensitivity are unclear. Experiments were performed to assess the short-term (days) and long-term (months) consequences of larval stage exposure to varying CO2 concentrations for calcifying bivalves. Higher CO2 concentrations depressed both calcification rates assessed using 45Ca uptake and RNA : DNA ratios in Mercenaria mercenaria and Argopecten irradians larvae with RNA : DNA ratios being highly correlated with larval growth rates (r2>0.9). These findings suggested that high CO2 has a cascading negative physiological impact on bivalve larvae stemming in part from lower calcification rates. Exposure to elevated CO2 during the first four days of larval development significantly depressed A. irradians larval survival rates, while a 10-day exposure later in larval development did not, demonstrating the extreme CO2 sensitivity of bivalve larvae during first days of development. Short- (weeks) and long-term (10 month) experiments revealed that individuals surviving exposure to high CO2 during larval development grew faster when exposed to normal CO2 as juveniles compared to individuals reared under ambient CO2 as larvae. These increased growth rates could not, however, overcome size differences established during larval development, as size deficits of individuals exposed to even moderate levels of CO2 as larvae were evident even after 10 months of growth under normal CO2 concentrations. This "legacy effect" emphasizes the central role larval stage CO2 exposure can play in shaping the success of modern-day bivalve populations

Global transcriptional responses of the toxic cyanobacterium, Microcystis aeruginosa, to nitrogen stress, phosphorus stress, and growth on organic matter

Whole transcriptome shotgun sequencing (RNA-seq) was used to assess the transcriptomic response of the toxic cyanobacterium Microcystis aeruginosa during growth with low levels of dissolved inorganic nitrogen (low N), low levels of dissolved inorganic phosphorus (low P), and in the presence of high levels of high molecular weight dissolved organic matter (HMWDOM). Under low N, one third of the genome was differentially expressed, with significant increases in transcripts observed among genes within the nir operon, urea transport genes (urtBCDE), and amino acid transporters while significant decreases in transcripts were observed in genes related to photosynthesis. There was also a significant decrease in the transcription of the microcystin synthetase gene set under low N and a significant decrease in microcystin content per Microcystis cell demonstrating that N supply influences cellular toxicity. Under low P, 27% of the genome was differentially expressed. The Pho regulon was induced leading to large increases in transcript levels of the alkaline phosphatase phoX, the Pst transport system (pstABC), and the sphX gene, and transcripts of multiple sulfate transporter were also significantly more abundant. While the transcriptional response to growth on HMWDOM was smaller (5–22% of genes differentially expressed), transcripts of multiple genes specifically associated with the transport and degradation of organic compounds were significantly more abundant within HMWDOM treatments and thus may be recruited by Microcystis to utilize these substrates. Collectively, these findings provide a comprehensive understanding of the nutritional physiology of this toxic, bloom-forming cyanobacterium and the role of N in controlling microcystin synthesis

The ability of macroalgae to mitigate the negative effects of ocean acidification on four species of North Atlantic bivalve

Coastal ecosystems can experience acidification via upwelling, eutrophication, riverine discharge, and climate change. While the resulting increases in pCO2 can have deleterious effects on calcifying animals, this change in carbonate chemistry may benefit some marine autotrophs. Here, we report on experiments performed with North Atlantic populations of hard clams (Mercenaria mercenaria), eastern oysters (Crassostrea virginica), bay scallops (Argopecten irradians), and blue mussels (Mytilus edulis) grown with and without North Atlantic populations of the green macroalgae, Ulva. In six of seven experiments, exposure to elevated pCO2 levels ( ∼ 1700&thinsp;µatm) resulted in depressed shell- and/or tissue-based growth rates of bivalves compared to control conditions, whereas rates were significantly higher in the presence of Ulva in all experiments. In many cases, the co-exposure to elevated pCO2 levels and Ulva had an antagonistic effect on bivalve growth rates whereby the presence of Ulva under elevated pCO2 levels significantly improved their performance compared to the acidification-only treatment. Saturation states for calcium carbonate (Ω) were significantly higher in the presence of Ulva under both ambient and elevated CO2 delivery rates, and growth rates of bivalves were significantly correlated with Ω in six of seven experiments. Collectively, the results suggest that photosynthesis and/or nitrate assimilation by Ulva increased alkalinity, fostering a carbonate chemistry regime more suitable for optimal growth of calcifying bivalves. This suggests that large natural and/or aquacultured collections of macroalgae in acidified environments could serve as a refuge for calcifying animals that may otherwise be negatively impacted by elevated pCO2 levels and depressed Ω.</p