Faculty-mentored researchers test the effects of vitamin A in prepubertal bulls

Research team (left to right): Maricela Andrade, Dr. Nicolas Negrin Pereira, and Marijo Wilkes
Research team (left to right): Maricela Andrade, Dr. Nicolas Negrin Pereira, and Marijo Wilkes

Undergraduate Biology students Marijo Wilkes and Maricela Andrade are learning important life lessons and applications of field and laboratory technologies, thanks to Dr. Nicolas ("Nico") Negrin Pereira. The research team is examining the effects of Vitamin A on several factors related to testicular growth and fertility in prepubertal beef bulls. Negrin Pereira (Assistant Professor in the Biology Department) has forged important partnerships with local beef farmers, including Arrin Baker, whose bull herd was used in this study. 

The researchers took weekly measurements of scrotal size in two groups of prepubertal bulls -- Vitamin A group and control group (no Vitamin A) -- and they used a portable Doppler ultrasound scanner to examine and image testicular parenchyma Pixel Intensity and Testicular Blood flow. Parameters of blood flow were measured by way of imagery, including flow velocity, Resistance Index (RI), and Pulsatility Index (PI). After a month, they castrated both groups of bulls and removed their testicles for morphometric measurements and cytology in the laboratory. 

Negrin Pereira has established key collaborations with researchers at NC State Animal Sciences Department, the Pathology Services Core at the Lineberger Comprehensive Cancer Center at the UNC School of Medicine (Chapel Hill), and the Biotechnology Research and Training Center at UNCP. Testicular parenchyma tissues were submitted to the Lineberger Comprehensive Cancer Center for processing. Counts of Sertoli and germ cells will be done by way of immunofluorescence and confocal microscopy at the Biotechnology Research and Training Center.

Negrin Pereira’s undergraduate researchers joined more than a hundred other students from across campus to present their research during the Eighteenth Annual UNC Pembroke Undergraduate Research and Creativity (PURC) Symposium on April 10th. Their poster caught the eye of the keynote speaker, Dr. Jennifer Gerz-Escandon (Assoc. Vice President for Academic Programs & Research, UNC System), who stopped by to chat with Maricela.

Marijo Wilkes is part of the UNC System Veterinary Education Access Scholars Program and will be entering NC State Veterinary College soon, while Maricela Andrade is a Biology major, considering different biomedical research career paths. Both students will be working over the summer analyzing ultrasonographic images and processing tissue samples for testicular cytology using immunofluorescent microscopy. Negrin Pereira added, “we are all excited to see our first data, but as a mentor it is gratifying to see your students progress and advance in their careers, where no doubt a brilliant future waits for these two young ladies”.

Negrin Pereira has mentored numerous students in research. Reflecting on the 2023-2024 academic year, however, he said, “I would like to recognize the awesome help from two of my research students Maricela Andrade and Marijo Wilkes.” 

Web manager’s note: Dr. Negrin Pereira, one of the newest members of the Biology faculty, teaches undergraduate courses in agricultural science, including Introduction to Animal Science, Principles of Animal Nutrition, and Animal Reproductive Physiology.