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Environmental Factor

August 2011

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Interns participate in a series of scientific presentations

By Eddy Ball and Josh Zeldin
August 2011

Humphrey Yao, Ph.D.

Yao was obviously more comfortable moving around and working the crowd, often with humor and direct engagement. Three of his postdoctoral assistants laughed along with trainees, as Yao laced his science with wit and charm. (Photo courtesy of Steve McCaw)

Valerie Davis, Ph.D.

Postdoctoral fellow Valerie Davis, Ph.D., has participated in a number of outreach workshops this year, and she's developing an engaging teaching style of her own. (Photo courtesy of Steve McCaw)

Sabrina Murray

Intern Sabrina Murray, a veterinary student, looked right at home at the microscope. For some of the younger interns, this was one of the first times they've used scopes with this degree of magnification. (Photo courtesy of Steve McCaw)

Stavros Garantziotis, M.D.

Garantziotis underscored nature's elegant design when he told the interns that artificial lungs work only for a couple of days at best. (Photo courtesy of Steve McCaw)

Zack McCaw

Back for his second year as an intern, Zack McCaw, center, looks as though Garantziotis' enthusiasm was contagious. McCaw is all eyes and ears as he joined Garantziotis on the fantastic voyage through the lung. (Photo courtesy of Steve McCaw)

An important component of the NIEHS Summer Internship Program (SIP) spanned June and July, as interns attended four scientific presentations to complement their bench training experience this summer. The series began with a presentation by Acting Scientific Director David Miller, Ph.D., June 16 (see story(, continuing with talks by Principal Investigators Humphrey Yao, Ph.D., Laboratory of Reproductive and Developmental Toxicology; Stavros Garantziotis, M.D., Laboratory of Respiratory Biology; and Patricia Jensen, Ph.D., Laboratory of Neurobiology.

As she did last summer, SIP Coordinator Debbie Wilson drew heavily on resources provided by NIEHS postdoctoral fellows and laboratory staff, who gave presentations, led group activities, and helped the featured speakers with hands-on activities. Attendance was excellent, with each of the presentations attracting a full audience of young people eager to learn more about the science conducted by investigators across several laboratories at NIEHS.

The talks were also webcast to trainees at NIH.

Reproductive biology

Yao, a developmental biologist who heads the NIEHS Reproductive Developmental Biology Group, focused his June 30 presentation on embryo development and sexual differentiation, abnormalities of which are linked to birth defects, such as ambiguous genitalia and pseudohermaphroditism, and conditions with a fetal origin that develop in adulthood. “Birth defects in reproductive organs are rarely fatal,” Yao explained, “but may result in fertility problems and abnormal growth in tissue that could lead to tumor formation when individuals reach adulthood.”

Ambiguous external genitalia occurs roughly in 1 of 2000 births, Yao said, and infertility is an increasingly common public health issue. The financial burden of treating infertility is significant, but there is no accurate way to estimate the social and emotional implications of health problems caused by abnormalities in embryo development.

Following Yao's introduction, postdoctoral fellows Valerie Davis, Ph.D., Nisha Cavanaugh, Ph.D., and Tracy Clement Ph.D., took the podium and provided more details on the reproductive system and examples of what research on reproductive biology is conducted at NIEHS. The presentation ended with an informal exercise to get interns involved in designing an experiment to answer a typical research question, whether maternal exposure to a certain chemical affects testes development of the offspring.

When interns had correctly identified the seven things an investigator needs to consider, postdoctoral fellows Sarah Swerdlow, Ph.D., and Staton Wade, Ph.D., opened up the auditorium to a bank of microscopes with slides showing sperm mobility and mouse embryos. Yao and his assistants helped interns understand what they were seeing.

Respiratory biology

Garantziotis, a pulmonologist who heads the NIEHS Matrix Biology Group and also serves as medical director of the NIEHS Clinical Research Unit, gave a presentation July 7 that offered both a sweeping overview of the lung and a fantastic voyage through its progressively smaller and more numerous passageways. He revealed his bias early in his talk, when he said, “The lung is the coolest organ in the body.” To back up that statement, he wowed his audience with the sheer volume of the lung - its 300 million alveoli and its total surface area of 450-900 square feet - as well its daily ventilation of approximately 10,000 liters of air each day per day at rest, as it filters some 10,000 liters of blood.

The lung's vulnerability to inhaled particles as large as one millimeter in diameter to ones smaller than 10 micrometers led naturally into a discussion of environmental airway disease, such as asthma and chronic obstructive pulmonary diseases (COPD). Garantziotis emphasized the public health implications of lung disease, noting COPD, the fourth most common cause of death worldwide, costs $40 billion annually in the U.S. alone. In developed countries, the leading cause of COPD is lifestyle, primarily smoking, but in the developing world, the main cause is indoor cooking with biomass.

NIEHS Biologist Michelle Sever followed Garantziotis with a discussion of her doctoral thesis on the association between indoor air pollution and stress related to community violence, on the one hand, and asthma among inner city children, on the other.


Jensen, a neuroscientist who heads the Developmental Neurobiology Group, wrapped up the series with her presentation on the environment and the developing brain July 14. Like Garantziotis, she impressed interns with the size of what she described as “the most complex organ in the body [that] controls all of our senses, our actions, perceptions, and thoughts.” She described the brain's approximately 100 billion neurons and 60 trillion synapses that occupy a three-pound structure about the size of a grapefruit. She used the visual image of the 1.4 billion acre Amazon rain forest, comparing the number of neurons to the number of trees there, and the number of synapses to the number of leaves on those trees.

Emphasizing the vulnerability of the brain, Jensen told the audience that it begins developing three weeks into gestation and isn't fully developed until late adolescence. Over this period of time, she said, there are critical periods when the brain is especially vulnerable to environmental insult from exposure to heavy metals, smoke, pesticides, and other compounds. Diseases that may be caused or aggravated by environmental exposures, such as autism spectrum disorders and Parkinson's, Jensen added, create a heavy public burden in terms of treatment costs and loss of productivity.

Jensen spoke briefly of the interplay of epidemiological, behavioral, and cellular and molecular studies in neurobiological research, as well as her current project involving genetic fate mapping of molecularly defined subdomains within the noradrenergic primordium. Interns spent the last half of the presentation period touring the five labs that make up the Laboratory of Neurobiology, and interacting with postdoctoral fellows who discussed ongoing projects in their respective groups.

(Josh Zeldin is a summer intern with the NIEHS Office of Communications and Public Liaison. He is a student at the University of North Carolina at Chapel Hill.)

Michelle Sever

Sever developed her interest in indoor air pollution during her work as a biologist in the Laboratory of Respiratory Biology and decided to pursue a doctorate in epidemiology. She traced her interest in environmental health back to her own experiences as a summer intern at NIEHS. (Photo courtesy of Steve McCaw)

Patricia Jensen, Ph.D.

Jensen, shown in her lab, said she wants to understand how the diversity in brain neurons comes about and how subpopulations of cells in the brain differ from one another. She said that during critical periods of development, environmental exposures can influence the making and pruning of synapses in the brain. (Photo courtesy of Steve McCaw)

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