Giant-celled Characeae (Chara australis Brown), grown for 4 months on 12/12 hr day/night cycle and summer/autumn temperatures, exhibited distinct concentration maxima in auxin (indole-3-acetic acid; IAA), melatonin and serotonin about 4 hr after subjective daybreak. These concentration peaks persisted after 3 day pretreatment in continuous darkness: confirming a circadian rhythm, rather than a response to "light on." The plants pretreated for 3 d in continuous light exhibited several large IAA concentration maxima throughout the 24 hr. The melatonin and serotonin concentrations decreased and were less synchronized with IAA. Chara plants grown on 9/15 hr day/night cycle for 4 months and winter/spring temperatures contained much smaller concentrations of IAA, melatonin and serotonin. The IAA concentration maxima were observed in subjective dark phase. Serotonin concentration peaks were weakly correlated with those of IAA. Melatonin concentration was low and mostly independent of circadian cycle. The "dark" IAA concentration peaks persisted in plants treated for 3 d in the dark. The plants pretreated for 3 d in the light again developed more IAA concentration peaks. In this case the concentration maxima in melatonin and serotonin became more synchronous with those in IAA. The abscisic acid (ABA) and jasmonic acid (JA) concentrations were also measured in plants on winter regime. The ABA concentration did not exhibit circadian pattern, while JA concentration peaks were out of phase with those of IAA. The data are discussed in terms of crosstalk between metabolic pathways.

In June 2016, massive cyanobacterial blooms occurred in the St. Lucie River in Florida, caused by nutrient and cyanobacterial-laden water releases from Lake Okeechobee. We independently collected and analyzed bloom material for cyanotoxin diversity and concentrations. The concentrations of microcystins, potent hepatotoxins, present in the bloom material greatly exceeded World Health Organization Guideline Values for drinking and recreational water. We also detected the neurotoxins anatoxin-a(S) and β-N-methylamino-L-alanine (BMAA). The Florida State Governor declared a state of emergency, but many affected aquatic recreational areas in St. Lucie County remained open during the bloom event without adequate hazard notification to citizens. During the bloom event, issues with preparedness, communication, sampling, analysis, closures and contingencies were observed. We suggest better ways that cyanobacterial bloom events can be predicted, managed, and mitigated in the future throughout the world. As similar problems with cyanobacterial bloom frequency and occurrence present worldwide, understanding governmental responses to the 2016 Florida incident can help in the development of effective mitigation and management strategies for future bloom events.

β-N-Methylamino-L-alanine (BMAA) is a naturally occurring non-protein amino acid produced by cyanobacteria, accumulated through natural food webs, found in mammalian brain tissues. Recent evidence indicates an association between BMAA and neurological disease. The accurate detection and quantification of BMAA in food and environmental samples are critical to understanding BMAA metabolism and limiting human exposure. To date, there have been more than 78 reports on BMAA in cyanobacteria and human samples, but different methods give conflicting data and divergent interpretations in the literature. The current work was designed to determine whether orthogonal chromatography and mass spectrometry methods give consistent data interpretation from a single sample matrix using the three most common analytical methods. The methods were recreated as precisely as possible from the literature with optimization of the mass spectrometry parameters specific to the instrument. Four sample matrices, cyanobacteria, human brain, blue crab, and Spirulina, were analyzed as 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) derivatives, propyl chloroformate (PCF) derivatives separated by reverse phase chromatography, or underivatized extracts separated by HILIC chromatography. The three methods agreed on positive detection of BMAA in cyanobacteria and no detected BMAA in the sample of human brain matrix. Interpretation was less clear for a sample of blue crab which was strongly positive for BMAA by AQC and PCF but negative by HILIC and for four spirulina raw materials that were negative by PCF but positive by AQC and HILIC. Together, these data demonstrate that the methods gave different results and that the choices in interpretation of the methods determined whether BMAA was detected. Failure to detect BMAA cannot be considered proof of absence.

Premise of the Study Research in Amaranthaceae could be accelerated by developing methods for targeted gene silencing. Most amaranths, including Amaranthus tricolor, produce betalains. However, the physiological and ecological roles of these pigments are uncertain. We sought to establish a virus‐induced gene‐silencing (VIGS) method for amaranths, using silencing of betalain pigments as a proof‐of‐principle. Methods We targeted AtriCYP76AD1, a putative cytochrome P450 component of the betalain biosynthetic pathway, using VIGS, and compared two different methods of introducing the VIGS construct into plants. We measured transcript abundance and concentrations of betalains and their l‐DOPA precursor in VIGS‐treated plants, and compared these to controls. Results We observed that when AtriCYP76AD1 was targeted by VIGS in normally red plants, AtriCYP76AD1 and the related genes AtriCYP76AD6 and AtriCYP76AD5 had diminished transcript abundance. Furthermore, newly emergent petioles and leaves of VIGS‐treated plants appeared green, betacyanin accumulation was strongly reduced, and l‐DOPA accumulation was increased. No betaxanthin could be detected in this variety of A. tricolor, either before or after VIGS treatment. Discussion These results help to establish the genetic basis of betalain synthesis in amaranths. Furthermore, this is the first report of VIGS in amaranths and demonstrates the potential of this technique for basic and applied research in these species.