Life in Plastic, It’s not Fantastic

Samuel Daughenbaugh, DePauw University

2DA71FE7-975A-4AA8-8A78-DF3D1E545F05The Problem: We live in a plastic world. Plastics have saturated all aspects of our daily lives and, as a consequence, have also entered the natural world.  About 8.3 billion metric tons have been produced in the past 60 years, playing a pivotal role in the advancement of modern society (Parker, 2018). Although they are used to create many things we enjoy and benefit from, there are serious consequences for the health of humans and the environment that are associated with their use.

We have found plastics in unexpected places, everywhere from human guts to the most remote locations on earth (Schwabl, 2018; Woodall, 2014). Plastics have a long list of negative effects on living organisms, but their impact in the ocean is of special concern. Pictures of turtles with straws up their noses, bottle caps spilling out of dead bird stomachs, and penguins strangled in plastic beverage rings are often posted on social media sites. Less widely known are the chemical additives that leach from plastics. Phthalates are one such group of additives that pose threats to the health of humans and marine life.

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Current Fort Johnson REU Interns (Julianna Duran not pictured) collecting plastic and sand dollars on Otter Island. (Photo credit: R. Podolsky)

Phthalates have been valuable to the plastic industry because they promote flexibility and durability in many plastics (EPA, 2017). An astounding 470 million pounds of phthalates are used in the United States every year (EPA, 2017). This presents a significant problem because phthalates interfere with the production of important hormones that regulate growth and metabolism in humans and other animals (Boas et al., 2012).

This summer I am exploring the effects of three different phthalates– dimethyl phthalate (DMP), di-n-butyl phthalate (DBP), and di-2-ethylhexyl phthalate (DEHP)–on the larval development of marine invertebrates, using the purple-spined sea urchin (Arbacia punctulata) as a model. Sea urchin larvae float freely in the water column for an extended period of time and, therefore, are vulnerable to many marine pollutants.

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Purple-spined sea urchin (Arbacia punctulata)

Sea urchins are an important model because they are closely related to humans. Both humans and sea urchins use a signaling hormone called thyroxine, which is especially important for growth in early developmental stages (Heyland et al., 2006). Exposure to phthalates can disrupt the production of thyroxine. Additionally, larvae are very important to study because they form the base of food webs. Being at the bottom of the food chain means they feed animals at higher levels, many of which humans rely on for protein. Therefore, understanding how phthalates affect sea urchin growth and metabolism can lead to new insights into how these pollutants directly and indirectly impact human health.

 Acknowledgements

I would like to thank my mentor, Dr. Robert Podolsky, for his continued support, guidance, and encouragement. This project is supported by the Fort Johnson REU Program, NSF DBI-1757899.

References

Boas, M., Feldt-Rasmussen, U., & Main, K. M. (2012). Thyroid effects of endocrine disrupting chemicals. Molecular and Cellular Endocrinology, 355(2), 240-248. 

Environmental Protection Agency (Ed.). (2017). Phthalates. America’s Children and the Environment, 3, 1-19.

Heyland, A., Price, D. A., Bodnarova-Buganova, M., & Moroz, L. L. (2006). Thyroid hormone metabolism and peroxidase function in two non-chordate animals. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution, 306B(6), 551-566.

Parker, L. (2018, December 18). A whopping 91% of plastic isn’t recycled. Retrieved from  http://www.nationalgeographic.com

Schwabl, P. (2018, October). Assessment of Microplastic Concentrations in Human Stool. Conference on Nano and microplastics in technical and freshwater systems, Monte    Verità, Ascona, Switzerland.

Woodall, L. C., Sanchez-Vidal, A., Canals, M., Paterson, G. L., Coppock, R., Sleight, V., . . . Thompson, R. C. (2014). The deep sea is a major sink for microplastic debris. Royal      Society Open Science, 1(4), 140317-140317. doi:10.1098/rsos.140317

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Hiding in plain sight

Brian Wuertz, Warren Wilson College

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How much do we really know about all the chemicals that we are exposed to every day? Do we even know when we come into contact with them? How much do we know about what is in homogenized milk, soda, stool softeners, baby formula, and personal care products such as eyeliner? The answer may be “not enough” for one compound found in all of those products, dioctyl sodium sulfosuccinate, or DOSS. DOSS has recently been identified by my mentor, Dr. Spyropoulos and his Ph.D. student, Alexis Temkin, as a probable obesogen. Obesogens are a class of compounds that promote obesity by interfering with the body’s hormone signaling pathways related to energy use, fat cell regulation, and inflammation. These pathways are especially important in the developing fetus, where hormone signals influence development and may have long lasting effects on the health of the child after birth (Holder 2016).

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I am working on a High Performance Liquid Chromatography  (HPLC) system, in the early stages of developing a method to measure the amount of DOSS in cell extracts. (More to come in future posts!)

We are especially concerned with regards to the developing fetus and child because stool softeners containing DOSS are are commonly taken by pregnant women. Approximately 35% of over 20,000 women who gave birth at MUSC in recent years reported taking a stool softener containing DOSS during their pregnancy. I am working to help understand the biochemical pathways DOSS may follow to affect changes in the  developing fetus through a mother’s exposure to DOSS. I am also working on a method to measure the amount of DOSS in cells so that we can learn where in the body DOSS goes and how much of it there actually is.

You might be wondering how this fits into the theme of marine organism health at this point since all I have talked about is human health and a compound found in products we put in our bodies, DOSS. A red flag was raised about DOSS through research on COREXIT, one of the agents used to clean up the Deepwater Horizon oil spill. Over 40 million gallons of COREXIT was dumped into the ocean as a part of the cleanup effort and DOSS is one of the major components (Temkin 2016).  DOSS was flagged as a potential human health hazard because of the research done on marine environmental degradation. It amazes me how a perhaps seemingly unrelated topic can end up having human health implications. I am excited to keep working on this puzzle to learn more about DOSS and how it interacts with the systems in our bodies!

Funding for this REU program is generously provided by the National Science Foundation and hosted by the College of Charleston. Dr Demetri Spyropoulos at the Medical University of South Carolina is graciously hosting my research project and providing mentorship.

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Sources:

Holder, B., Jones, T., Sancho Shimizu, V., Rice, T.F., Donaldson, B., Bouqueau, M., Forbes, K., and Kampmann, B. (2016). Macrophage Exosomes Induce Placental Inflammatory Cytokines: A Novel Mode of Maternal–Placental Messaging. Traffic 17, 168–178.
Temkin, A.M., Bowers, R.R., Magaletta, M.E., Holshouser, S., Maggi, A., Ciana, P., Guillette, L.J., Bowden, J.A., Kucklick, J.R., Baatz, J.E., et al. (2016). Effects of Crude Oil/Dispersant Mixture and Dispersant Components on PPARγ Activity in Vitro and in Vivo: Identification of Dioctyl Sodium Sulfosuccinate (DOSS; CAS #577-11-7) as a Probable Obesogen. Environ Health Perspect 124, 112–119.

 

 

 

Humans and gators and chickens, oh my!

Jimena B. Pérez-Viscasillas, University of Puerto Rico at Mayaguez

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When I first applied to this Marine Biology REU, in a lab that works mostly with alligators, at a Marine Science Campus right by the Charleston shore, I never thought I’d end up working with chickens. Yes, you read correctly: chickens, of the Chick-Fill-A and Kentucky Fried sort. I was surprised too, naturally, but it turns out the reason behind it is actually pretty important.

A couple of years ago, a group of scientists noticed some alligator populations in Florida weren’t doing too well. Their fertility levels were decreasing and a lower percentage of the eggs laid were hatching. Upon further study, evidence pointed towards a likely culprit: anthropogenic chemical contaminants in the environment. These contaminants were negatively affecting the gators’ hormone production and, in turn, their reproductive systems.

What do these gators have to do with chickens, though? Perhaps more importantly, what do they have to do with us? Let’s review some basic bio…

Figure 1: Vertebrate phylogenetic tree. Amniotes are organisms which have adapted to terrestrial reproduction. This group includes birds, reptiles, and mammals. (Graphic taken from: UCL)

There are some terrestrial animals which lay eggs (like chickens and gators) and some that carry their young in the womb, inside the placenta (like us). Both types of organisms, collectively called amniotes, have much of the same tissues surrounding their embryos during development. This shared characteristic means that we may be able to study some egg-laying animals to better understand our own reproductive systems.

Figure 2: A chick embryo and membrane. The membrane I’m going to be studying is that which lines the inside of the shell. Its called the chorioallantoic membrane, and it allows gas and waste exchange between the embryo and the environment. (Taken from Angiogenesis Laboratory Amsterdam)

Before we can use these organisms’ tissues as models of our own, however, we have to make sure we understand how they function. This is where I (and the chickens) come in. This summer, I’m going to be measuring how (and if), at different stages of development, the egg membrane of chickens produces hormones called prostaglandins. Prostaglandins play a major role in the immune system, as well as the body’s general regulation and reproduction. This preliminary research would help us better understand these sentinel species and allow us to later assess how their endocrine, immune and reproductive systems are being compromised by environmental pollutants. If we know how chemical contaminants in the environment are having negative effects on their reproduction, what might it tell us about how they’re affecting our health and reproduction?

To learn more about my project, check back for further posts!

Acknowledgements

This research, conducted at Dr. Louis Guillete’s MUSC Laboratory, is made possible thanks to funding from NSF and the College of Charleston. Further equipment and facilities are provided by the Hollings Marine Laboratory.

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References:

Bellairs, Ruth & Osmond, Mark. The Atlas of Chick Development.  San Diego, California: Elsevier Academic Press, 2005. Print.

Guillette LJ Jr. “The evolution of viviparity in amniote vertebrates—new insights, new questions.” J Zool  223 (1991): 521–526. Web. 10 June 2015.

Guillette LJ Jr. “The evolution of viviparity in lizards.” Bioscience 43 (1993): 742–751. Print.

Kalinski P. “Regulation of Immune Responses by Prostaglandin E2.” J Immunol 188 (2012):21-28. Web. 10 June 2015.

Kluge AG. Chordate Structure and Function. New York: Macmillan Publishing Co., Inc.; 1977. Print.

Milnes MR, Guillette LJ Jr. “Alligator Tales: New Lessons about Environmental Contaminants from a Sentinel Species.” BioScience 58.11 (2008): 1027-1036. Web. 15 June 2015.  doi:10.1641/B581106