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Neurological illnesses associated with Florida red tide (Karenia brevis) blooms.

ABSTRACT: Human respiratory and gastrointestinal illnesses can result from exposures to brevetoxins originating from coastal Florida red tide blooms, comprising the marine alga Karenia brevis (K. brevis). Only limited research on the extent of human health risks and illness costs due to K. brevis blooms has been undertaken to date. Because brevetoxins are known neurotoxins that are able to cross the blood-brain barrier, it is possible that exposure to brevetoxins may be associated with neurological illnesses. This study explored whether K. brevis blooms may be associated with increases in the numbers of emergency department visits for neurological illness. An exposure-response framework was applied to test the effects of K. brevis blooms on human health, using secondary data from diverse sources. After controlling for resident population, seasonal and annual effects, significant increases in emergency department visits were found specifically for headache (ICD-9 784.0) as a primary diagnosis during proximate coastal K. brevis blooms. In particular, an increased risk for older residents (≥55 years) was identified in the coastal communities of six southwest Florida counties during K. brevis bloom events. The incidence of headache associated with K. brevis blooms showed a small but increasing association with K. brevis cell densities. Rough estimates of the costs of this illness were developed for hypothetical bloom occurrences.

SUBMITTER: Diaz RE

PROVIDER: S-EPMC9933543 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Neurological illnesses associated with Florida red tide (Karenia brevis) blooms.

Diaz Roberto Efrain RE Friedman Melissa A MA Jin Di D Beet Andrew A Kirkpatrick Barbara B Reich Andrew A Kirkpatrick Gary G Ullmann Steven G SG Fleming Lora E LE Hoagland Porter P

Harmful algae 20190201

Human respiratory and gastrointestinal illnesses can result from exposures to brevetoxins originating from coastal Florida red tide blooms, comprising the marine alga Karenia brevis (K. brevis). Only limited research on the extent of human health risks and illness costs due to K. brevis blooms has been undertaken to date. Because brevetoxins are known neurotoxins that are able to cross the blood-brain barrier, it is possible that exposure to brevetoxins may be associated with neurological illnes ...[more]

PMID: 30928012

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Project description:BACKGROUND:The role of coastal nutrient sources in the persistence of Karenia brevis red tides in coastal waters of Florida is a contentious issue that warrants investigation into the regulation of nutrient responses in this dinoflagellate. In other phytoplankton studied, nutrient status is reflected by the expression levels of N- and P-responsive gene transcripts. In dinoflagellates, however, many processes are regulated post-transcriptionally. All nuclear encoded gene transcripts studied to date possess a 5' trans-spliced leader (SL) sequence suggestive, based on the trypanosome model, of post-transcriptional regulation. The current study therefore sought to determine if the transcriptome of K. brevis is responsive to nitrogen and phosphorus and is informative of nutrient status. RESULTS:Microarray analysis of N-depleted K. brevis cultures revealed an increase in the expression of transcripts involved in N-assimilation (nitrate and ammonium transporters, glutamine synthetases) relative to nutrient replete cells. In contrast, a transcriptional signal of P-starvation was not apparent despite evidence of P-starvation based on their rapid growth response to P-addition. To study transcriptome responses to nutrient addition, the limiting nutrient was added to depleted cells and changes in global gene expression were assessed over the first 48 hours following nutrient addition. Both N- and P-addition resulted in significant changes in approximately 4% of genes on the microarray, using a significance cutoff of 1.7-fold and p ? 10-4. By far, the earliest responding genes were dominated in both nutrient treatments by pentatricopeptide repeat (PPR) proteins, which increased in expression up to 3-fold by 1 h following nutrient addition. PPR proteins are nuclear encoded proteins involved in chloroplast and mitochondria RNA processing. Correspondingly, other functions enriched in response to both nutrients were photosystem and ribosomal genes. CONCLUSIONS:Microarray analysis provided transcriptomic evidence for N- but not P-limitation in K. brevis. Transcriptomic responses to the addition of either N or P suggest a concerted program leading to the reactivation of chloroplast functions. Even the earliest responding PPR protein transcripts possess a 5' SL sequence that suggests post-transcriptional control. Given the current state of knowledge of dinoflagellate gene regulation, it is currently unclear how these rapid changes in such transcript levels are achieved.

Project description:Nearly all annual blooms of the toxic dinoflagellate Karenia brevis (K. brevis) pose a serious threat to coastal Southwest Florida. These blooms discolor water, kill fish and marine mammals, contaminate shellfish, cause mild to severe respiratory irritation, and discourage tourism and recreational activities, leading to significant health and economic impacts in affected communities. Despite these issues, we still lack standard measures suitable for assessing bloom severity or for evaluating the efficacy of modeling efforts simulating bloom initiation and intensity. In this study, historical cell count observations along the southwest Florida shoreline from 1953 to 2019 were used to develop monthly and annual bloom severity indices (BSI). Similarly, respiratory irritation observations routinely reported in Sarasota and Manatee Counties from 2006 to 2019 were used to construct a respiratory irritation index (RI). Both BSI and RI consider spatial extent and temporal evolution of the bloom, and can be updated routinely and used as objective criteria to aid future socioeconomic and scientific studies of K. brevis. These indices can also be used to help managers and decision makers both evaluate the risks along the coast during events and design systems to better respond to and mitigate bloom impacts. Before 1995, sampling was done largely in response to reports of discolored water, fish kills, or respiratory irritation. During this timeframe, lack of sampling during the fall, when blooms typically occur, generally coincided with periods of more frequent-than-usual offshore winds. Consequently, some blooms may have been undetected or under-sampled. As a result, the BSIs before 1995 were likely underestimated and cannot be viewed as accurately as those after 1995. Anomalies in the frequency of onshore wind can also largely account for the discrepancies between BSI and RI during the period from 2006 to 2019. These findings highlighted the importance of onshore wind anomalies when predicting respiratory irritation impacts along beaches.

Project description:To investigate a Florida manatee (Trichechus manatus latirostris) mortality event following a red tide bloom in Southwest Florida, a RNA-Seq experiment was conducted. Cell processes such as immune response, cell proliferation and differentiation and apoptosis were among the most affected by red tide. These were involved in potential diseases such as neoplasms, inflammation, and wounds and injuries, among others. There were both up-regulated and down-regulated genes, but the highest fold changes relative to controls were for genes that were down-regulated. Piccolo presynaptic cytomatrix protein (PCLO) gene, the one most down-regulated (fold change -9.93; p-value 0.0009) is associated with neurotransmitter release, cognitive functioning, neuronal loss, and neuronal synapse function. Another gene that has a similar function, ankyrin 2, neuronal, transcript variant 1 (ANK2) was also down-regulated (fold change -8.66; p-value 0.0023). ANK2 is associated with the stability of neuron synapses. Two immune genes, interleukin 6 (interferon, beta 2) (IL6) and zinc finger protein 804B (ZNF804B), were down-regulated (fold change -9.31; p-value 0.000003 and fold change -8.90; p-value 0.0164, respectively). Interleukin 6 encodes proteins involved in acute phase response, inflammation, and autoimmune response. ZNF804B is associated with neuronal chemokine and cytokine regulation, autoimmune response, and immune activation. The family with sequence similarity 186, member A (FAM186A) gene was down-regulated (fold change -8.79; p-value 0.0143). FAM186A gene mutation is associated with tumor metastasis in colorectal cancer tumors. Among the most up-regulated genes, CCAAT/enhancer binding protein (C/EBP) is involved in granulocytic differentiation and also involved with the immune system. Determining the differentially expressed genes associated with red tide enhances our understanding of manatee immune response to red tide toxins and aids in the development of red tide biomarkers. This information will better assist clinicians and researchers in diagnosing and treating future illnesses.

Dataset Information

Neurological illnesses associated with Florida red tide (Karenia brevis) blooms.

Publications

Neurological illnesses associated with Florida red tide (Karenia brevis) blooms.

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