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September 2011

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NIEHS mentoring makes summer special for Hispanic intern

By Eddy Ball
September 2011

Yasmin Crespo-Mejias

Crespo-Mejias, above, works with an automatic tissue processor, one of several advanced laboratory instruments her internship gave her an opportunity to access this summer. (Photo courtesy of Steve McCaw)

left to right, Yasmin Crespo-Mejias, Humphrey Yao, Ph.D., and Karina Rodriguez, Ph.D.

Crespo-Mejias, left, was joined at her microscope by Yao, center, and Rodriguez, right. (Photo courtesy of Steve McCaw)

From her first contact with NIH up to her last day at NIEHS Aug. 12, summer intern Yasmin Crespo-Mejias enjoyed the support and encouragement of quality mentors -from her colleagues in her lab, the NIEHS Summer Internship Program(, and the NIH Hispanic Employment Program.

Crespo-Mejias, a junior at the University of Puerto Rico (UPR)( Exit NIEHS, was the first intern to train in the NIEHS Reproductive Developmental Biology Group headed by Humphrey Yao, Ph.D. She was one of six interns, five of them working at NIH labs in Bethesda, Md., who benefited from outreach efforts led this spring and summer by Gerard Roman, the NIH equal opportunity and diversity management specialist on-site at NIEHS and manager of the NIH Hispanic Employment Program.

Describing her experience at NIEHS, Crespo-Mejias said, “The resources here are incredible, much better than what's available for undergraduates at the university. I was able to follow through with designing and carrying out a controlled experiment, as I got to see how real-world scientific discoveries happen.”

Designing and carrying out a study of endocrine disruption

Crespo-Mejias worked with Yao and others in the group, especially biologist Karina Rodriguez, Ph.D., from June 7, one day after her final exam of the year, to Aug. 12, when she returned home to get ready to begin the fall semester at her university's Rio Piedras Campus the following Monday. During her ten-week internship, she was involved in her summer project, a pilot study testing the hypothesis, “In Utero Exposure to Bisphenol A Disrupts Testis Development in Mouse Embryos,” as first author on an abstract displayed at the SIP annual poster session July 28 (see related story(

Using CD-1 mice, Crespo-Mejias administered four treatments to pregnant mice - the synthetic estrogen diethylstilbestrol (DES), which has known effects on testis development, as a positive control; BPA in high and low concentrations as experimental dose; and corn oil as a vehicle control. Her preliminary data bore out the hypothesis, suggesting that BPA exposure has an adverse effect on the embryonic development of the testes as shown by histological as well as gene expression analysis.

Taking the next steps

Yao, who was lead researcher on the study, said he was impressed by Crespo-Mejias' understanding of what's necessary for designing an effective study with preliminary data that can be replicated in other laboratories. “Because of Yasmin's careful design,” Yao said, “there is strong support for her hypothesis, and we plan to pursue the study with a larger sample size.”

The next step for Crespo-Mejias could be presenting her findings at the national conference of the Society for Advancement of Chicanos and Native Americans in Science (SACNAS) Oct. 27-30 in San Jose, Calif. She has applied for a travel grant to display her poster at the meeting, whose theme in 2011 is “Empowering Innovation and Synergy Through Diversity.”

Crespo-Mejias said she'd like to come to NIEHS next summer. Then, the next big decision for her will be whether to apply to graduate school or medical school following graduation.

Promoting diversity in science

For Roman, reaching out to young Hispanics is well worth the effort. “It's clear that diversity makes for better science,” he explained. “We benefit as a whole from the diverse perspectives that people from different backgrounds and heritages bring to scientific discovery, as well as their often keener awareness of the health disparities that exist in different communities.” Roman added that the NIH leadership has repeatedly affirmed its commitment to building an ever more diverse scientific workforce.

A winning combination for quality mentoring

As helpful as the NIH Hispanic Employment Program was for helping Crespo-Mejias find the right scientific fit for her internship at NIEHS, she had little idea that she would also find a perfect match for her mentoring needs here.

This summer, Crespo-Mejias worked side by side with Rodriguez who first came to NIEHS as an undergraduate student at North Carolina State University. She went on to complete her undergraduate work, her Ph.D., and postdoctoral training while affiliated with the Institute. Since joining NIEHS as a permanent employee, Rodriguez has been involved in mentoring postdocs and interns in the Laboratory of Reproductive and Developmental Toxicology. Roman said of her, “If anyone knows something about good science and good mentoring at the NIEHS, Karina does.” 

Although this was Yao's first year mentoring a summer intern at NIEHS, in his previous position as an associate professor at the University of Illinois at Urbana-Champaign, he had been a mentor in a summer program for minority students that included three young scientists from Puerto Rico.

Other members of the close-knit group, which includes postdoctoral fellows Heather Franco, Ph.D., and Erica Ungewitter, Ph.D., as well as predoctoral fellow Chang Liu, guided her through her summer project. As Yao said, “Yasmin's pilot study involved a lot of work for her in such a short period of time.”

Her success, as Rodriguez observed, was rooted in her positive attitude and work ethic. “She was very interested, eager to learn and understand her experiments, and she worked very, very hard this summer on a tough project.”

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