(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.
UTSA researchers are exploring matter at the atomic level with Helenita. It's one of the most powerful microscopes in the world, with the ability to operate near the theoretical limit of resolution. At 9 feet, 2 inches tall and weighing more than two tons, Helenita can dissect almost anything. With Helenita's resolution, researchers can study particles atom by atom to see how they behave.
That's critical in developing nanotechnology that will help diagnosis early-stage breast cancer or make helmets that are uber strong. Moreover, the detail that Helenita provides will allow nanotechnology researchers to create new therapies and treatments to fight a wide range of human diseases.
Did you know? Helenita can magnify a sample 20 million times its size, which would make a strand of human hair the size of San Antonio.
Join AIA San Antonio’s Women in Architecture group for their networking and happy hour event, where all design professionals are welcome.
Liberty Bar, 1111 S. Alamo St.
This documentary, presented by the San Antonio Film Festival, documents the experience of re-entry after incarceration. The film features Michael Gilbert, associate professor in the department of criminal justice and director of the Office of Community and Restorative Justice program at UTSA.
Tobin Center for the Performing Arts, 100 Auditorium Circle
Discover resources and strategies for teaching Tejano history and culture and get a special educator's tour of the new long-term exhibit, Los Tejanos.
Institute of Texan Cultures, 801 E. César E. Chávez Blvd.
This cowboy-themed programming, offered in conjunction with Our Kids Magazine's Kidcation Week, gives families the opportunity to visit with cowboy docents, enjoy readings and visit activity tables.
Institute of Texan Cultures, 801 E. Cesar E. Chavez Blvd.
The UTSA Alumni Association hosts this annual gala honoring the Alumna of the Year, Alumnus of the Year and the Alumnus of the Year Lifetime Achievement award winners.
Hyatt Regency Hill Country Resort & Spa, 9800 Hyatt Resort Dr.
Victor Cyrus, Jr will see his first book of poetry published this fall
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