Nav: Home

Weathered oil from DW Horizon spill may threaten fish embryos and larvae development

July 12, 2016

MIAMI-A research team led by scientists at the University of California, Riverside and the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science have found that ultraviolet light is changing the structure of the Deepwater Horizon (DWH) oil components into something more toxic, further threatening numerous commercially and ecologically important fishes. The DWH oil spill, in which more than three million barrels of crude oil got released in 2010 into the northern Gulf of Mexico, is the worst oil disaster in US history, contaminating the spawning habitats for many fishes.

"Ours is the first experiment evaluating the effects of DWH oil on the genetic responses of mahi-mahi embryos and larvae," said Daniel Schlenk, a professor of aquatic ecotoxicology, who led the study published in Environmental Science and Technology. "It is also the first experiment of this nature on a lifestage and species that was likely exposed to the oil. We found that the weathering of oil had more significant changes in gene expression related to critical functions in the embryos and larvae than the un-weathered oil. Our results predict that there are multiple targets of oil for toxicity to this species at the embryonic life stage."

First, the researchers exposed the fish embryos to the oils at three different time points: 24 hour post fertilization, 48-hours post fertilization, and 96-hours post fertilization. (Hatching to larvae in mahi-mahi occurs at 48-hours post fertilization; the researchers bracketed this time point at 24-hours post fertilization and 96-hours post fertilization.) Then, the researchers collected transcripts of all the genetic information at each time point and evaluated these transcripts using novel bioinformatic methods. Finally, they evaluated the toxicity and heart functions in animals using the embryos' gene expression to predict biochemical, cellular, and tissue targets where the oil was causing an effect.

For their experiments, Schlenk and UM Rosenstiel School scientists caught the mahi-mahi off the coast of Miami, Fla., and exposed embryos to two types of oil: one set of embryos was exposed to slick oil (weathered) from the spill while another set was exposed to oil that came from the source of the spill. The researchers carried out the experiment this way because fish in the northern Gulf of Mexico had been exposed during the spill to both types of oil. Their study attempted to understand which of the two oils - slick oil or source oil - is worse for the fish and how oil affects development.

"This study exemplifies a fruitful collaboration between UC Riverside and the UM Rosenstiel School to identify molecular targets for oil toxicity," said UM Rosenstiel School Professor Martin Grosell, lead of the RECOVER (the Relationship of Effects of Cardiac Outcomes in fish for Validation of Ecological Risk) consortium and co-author of the study. "In addition to impacts on heart development and function, the gene expression results illustrate the peripheral components of the nervous system involved in sensory function is impaired by oil exposure during early development."

Sensory function is important for prey detection and predator avoidance.

"We found that the heart, eye and neurological function were affected," Schlenk said. "In collaboration with other consortia members from the Universities of Miami, Texas, and North Texas, we are now following up on these results. Previous studies have shown that the heart is the primary target for oil. Our study shows that in addition to heart function, risk and recovery should also examine eye and neuronal function."

Video: https://youtu.be/g6GuocAXCbk

The approximately four-month study was expedited by a unique software, On-RAMP, that the researchers used to identify the gene signatures from the fish.

"Normally, it can take months to annotate the genes and identify the regulatory directions of expression," Schlenk explained. "But by using On-RAMP, we could identify the genomic responses in a matter of weeks, allowing pathway analyses with sophisticated software normally only used for human/mice responses."
-end-
The research was funded by the Gulf of Mexico Research Initiative, Grant No: SA-1520, as well as the Relationship of Effects of Cardiac Outcomes in fish for Validation of Ecological Risk (RECOVER) consortium.

The co-authors of the study include: Schlenk, Elvis Genbo Xu, Graciel Diamante and Juliane Freitas from UC Riverside; Edward M. Mager, Martin Grosell, Christina Pasparakis, Lela S. Schlenker, John D. Stieglitz, and Daniel Benetti from the UM Rosenstiel School; and E. Starr Hazard, Sean M. Courtney and Gary Hardiman at the Medical University of South Carolina.

Next, the research team will follow up with whole animal physiological and behavioral effects to see if the newly identified molecular responses can be linked to function.

About the University of Miami's Rosenstiel School

The University of Miami is one of the largest private research institutions in the southeastern United States. The University's mission is to provide quality education, attract and retain outstanding students, support the faculty and their research, and build an endowment for University initiatives. Founded in the 1940's, the Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, visit: http://www.rsmas.miami.edu.

University of Miami Rosenstiel School of Marine & Atmospheric Science

Related Embryos Articles:

Turtle embryos play a role in determining their own sex
In certain turtle species, the temperature of the egg determines whether the offspring is female or male.
Early in vitro testing for adverse effects on embryos
ETH researchers have combined embryonic cells and liver cells in a new cell culture test.
Embryos' signals take multiple paths
Rice University bioscientists uncover details about how embryonic stem cells respond to the collection of signals that direct their differentiation into blood, bone and tissue.
Are mosaic embryos the 'dark horse' of IVF?
New research conducted by scientists at the Oregon National Primate Research Center at OHSU is the first to confirm in a nonhuman primate model, that mosaic embryos can adapt to their abnormalities and persist in development, resulting in positive IVF outcomes.
Embryos' signaling proteins go with the flow
Protein signaling in the rapidly differentiating cells of embryos is far more complex than previously thought, as pathways take cues from many other players.
More Embryos News and Embryos Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...