Detecting Sublethal Effects of Harmful Algal Blooms in Mammalian and Avian Cells

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USGS Researchers are collaborating to study avian and mammalian cells to detect sublethal toxin effects following exposure to harmful algal blooms. 

The Science Issue and Relevance:  Algal and cyanobacterial blooms pose risks to human and animal health and ecosystem sustainability around the world.  Some blooms produce toxins that can lead to illness or mortality when animals and humans are exposed; such blooms are thus referred to as harmful algal blooms (HABs).  Contact with recreational and drinking water provides an opportunity for inhalation, ingestion, and dermal exposures to cyanotoxins.  Microcystins are acutely hepatotoxic peptides produced by cyanobacteria in both marine and freshwater ecosystems.  Being among the most reported and chemically defined cyanotoxins, microcystin exposures can be acute or chronic.  The most common of these is microcystin LR (MC-LR), which has known effects on mammals, including liver cancer, neurodegenerative diseases, and fertility problems.  Effects are variable in other species.  Once exposed to MC-LR, animal cell structures and functions can be altered.  Thus, biomarkers can be used to measure the effect in target cells to indicate the magnitude of responses which may be occurring prior to health impairment.

Microcystin

Chemical structure of microcystin-LR (PubChem)

Methodology for Addressing the Issue:  Biomarkers of sublethal effects will be monitored by flow cytometry and epi-fluorescent microscopy.  Exposures will be performed at the avian organismal- and the mammalian cell levels.  First, adult mallard ducks (Anas platyrhynchos) will be dosed with MC-LR so that organ-level pathologies can be described.  Cell from perfused livers will be examined to assess hepatocyte metabolism and viability; testes may be obtained to measure sperm quality parameters, such as motility.  Secondly, mouse (Mus musculus) primary liver cell cultures will be exposed to MC-LR concentrations to develop a gradient of biomarker responses along the MC-LR adverse outcome pathway (e.g., cell metabolism, genotoxicity, viability, and cytoskeletal structure).  Thus, by studying avian and mammalian cells, detecting the sublethal toxin effects after exposure is possible.  Additionally, selected consumable chemical inhibitors will be tested to determine their ability to interrupt pathways advancing toward cell damage.  By subjecting animal cells to known concentrations of this cyanotoxin, it will be possible to better diagnose animals exposed to HAB toxins in the wild.  Also, cell cultures exposed to HAB chemical mixtures in media under investigation can measure adverse effects and identify possible thresholds of concern. 

HAB in Lake Pontchartrain

Harmful Algal Bloom (HAB) in Lake Pontchartrain, Louisiana in 2019

Future Steps: By characterizing biomarkers of effect in mouse liver primary cell cultures exposed to defined levels of MC-LR, predictions on mammalian health outcomes can be projected and connected back to relevant threshold concentrations to better understand when effects might occur. Additionally, ameliorative effects of inhibitors may be candidate proactive preventatives that could be consumed should a human or animal need treatment prior to, or following, an exposure event. Environmental samples will be processed for cell culture exposures.  Moreover, this information will benefit veterinarians and wildlife health professionals as they diagnose and treat animals exposed to HABs.