(Sept. 24, 2012) -- In collaboration with scholars at the University of Hawaii and the University of Pennsylvania School of Medicine, a group of researchers led by John McCarrey, the UTSA College of Sciences' Kleberg Distinguished Chair in Cellular and Molecular Biology, and his graduate student Eric de Waal, who recently received his Ph.D. degree from UTSA, have demonstrated that the hormones known as gonadotropins lead to an increase in epimutations in mice produced in vitro.
The findings are important because they call into question the safety of the methods that are commonly used when couples use the in vitro fertilization process to have children.
The epigenome is the mechanism that programs the genome to control gene expression in each type of cell, and this ultimately decides one's outward appearance and influences development. Epimutations can lead to changes in appearance, development or cellular function when they disrupt the normal function of one or more genes in a cell.
Assisted reproductive technologies (ART) such as in vitro fertilization are a commonly accepted practice and account for more than four million children born worldwide so far, however caution persists among some scholars who point out that the long-term safety of these methods remains generally unknown. Most of the people conceived with the help of ART are currently still under the age of 35.
To better understand how ART and epimutations are linked, the scholars compared the frequency of epimutations in mice produced through an ART process called intracytoplasmic sperm injection (ICSI). They found the epimutation rate to be elevated in mice produced by this method when compared to that in naturally conceived mice.
Next, they compared the frequency of epimutations in three groups of mice: (1) mice produced by natural conception, (2) ICSI-derived mice and (3) mice derived through a process called somatic cell nuclear transfer (SCNT), also known as "cloning". They expected the epimutation rates in the cloned SCNT-derived mice to be higher than those in the ICSI mice. They were surprised, however, to find that the ICSI-derived mice had a higher rate of epimutations than the SCNT-derived mice.
The scholars then reasoned that since gonadotropin-stimulated eggs were used to produce both the ICSI and SCNT-derived offspring, but the nucleus in the egg used for SCNT was then replaced with another nucleus that had not been stimulated with gonadotropin, the lingering effects of gonadotropin exposure in the ICSI-derived offspring must be related to the higher incidence of epimutations in these mice. To test this idea, they subjected female mice to gonadotropin stimulation and then allowed the mice to reproduce naturally to isolate the effects of gonadotropins.
Ultimately, they found that the offspring produced from females subjected to gonadotropin stimulation displayed the same elevated incidence of epimutations they observed in the mice produced by ICSI, confirming that gonadotropin stimulation is a significant factor in inducing epimuations.
Although the mouse sample size the researchers used was small, McCarrey says the findings warrant some caution about the methods associated with ART and call for additional study to determine if the findings hold true in humans.
"ART now accounts for one to four percent of all births in developed countries, so we must work to make this process as completely safe as possible" said McCarrey. "Our results suggest that gonadotropin stimulation, which is typically used in every ART procedure, contributes to the formation of epimutations in the offspring produced. We want to understand why this happens, how it happens and what long-term effects this causes."
The research is available in Human Molecular Genetics.
Celebrate 40 years of BestFest, an annual event hosted by Roadrunner Productions as a part of UTSA Homecoming festivities. The event will feature a carnival, food and drink booths, a golf cart parade, firework and live music from Anthem.
Brackenridge Lot 1, Main Campus
Celebrate homecoming as the Roadrunners take on Rice. Come early for the Spirit Walk, tailgating, games, music and food. Stick around for a halftime show with SOSA and the crowning of Mr. and Ms. UTSA.
Alamodome, 100 Montana St., Downtown San Antonio
The Leadership Storytelling Homecoming Brunch brings together UTSA alumni and students to share a delicious meal as well as a roundtable conversation about how experiences in college carry us forward on unique leadership journeys.
University Center, Denman Room (UC 2.01.28), Main Campus
The conference is dedicated to sharing recent knowledge and experiences gained in the area of Big Data by researchers in academia, industry and the government sectors within the areas of business, national security, infrastructure, healthcare and visualization.
H-E-B University Center Ballroom (HUC 1.104), Main Campus
Former National Security Advisor Susan Rice, via webcast, will examine America’s economic, political and security relations with China during CHINA Town Hall, an 80-city live discussion and Q&A on China and Sino-American relations.
Building Building, Richard Liu Auditorium (BB 2.01.02), Main Campus
The African American Studies program proudly presents William "Cruz" Shaw, San Antonio City Councilman and UTSA Alumnus. Event is free and open to the public.
University Center, Retama Auditorium (UC 2.02.02), Main Campus
The graduate fair is an opportunity for the UTSA student body and local San Antonio community to learn about graduate education opportunities. The event is free and open to the public.
H-E-B University Center Ballroom (1.104), Main Campus
President Taylor Eighmy is inviting all UTSA students to "Pizza With The Prez." Come grab a slice of pizza and take the opportunity to introduce yourself to the President. Pizza while supplies last.
Frio Street Building, Food Court Commons Area, Downtown Campus
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