Related Experiment Video
Updated: Feb 10, 2026

Fluorimetric Techniques for the Assessment of Sperm Membranes
Published on: November 28, 2018
Effect of Heat Stress on Sperm DNA: Protamine Assessment in Ram Spermatozoa and Testicle
Thais Rose Dos Santos Hamilton1, Adriano Felipe Perez Siqueira1, Letícia Signori de Castro1
1Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of Sao Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, 05508 270, Cidade Universitária, Sao Paulo, SP, Brazil.
Abstract:
Sperm DNA fragmentation is considered one of the main causes of male infertility. The most accepted causes of sperm DNA damage are deleterious actions of reactive oxygen species (ROS), defects in protamination, and apoptosis. Ram sperm are highly prone to those damages due to the high susceptibility to ROS and to oxidative stress caused by heat stress. We aimed to evaluate the effects of heat stress on the chromatin of ejaculated and epididymal sperm and the activation of apoptotic pathways in different cell types in ram testis. We observed higher percentages of ejaculated sperm with increased chromatin fragmentation in the heat stress group; a fact that was unexpectedly not observed in epididymal sperm. Heat stress group presented a higher percentage of spermatozoa with DNA fragmentation and increased number of mRNA copies of transitional protein 1. Epididymal sperm presented greater gene expression of protamine 1 on the 30th day of the spermatic cycle; however, no differences in protamine protein levels were observed in ejaculated sperm and testis. Localization of proapoptotic protein BAX or BCL2 in testis was not different. In conclusion, testicular heat stress increases ram sperm DNA fragmentation without changes in protamination and apoptotic patterns.
Related Concept Videos
Responses to Heat and Cold Stress
Sperm Transport
The maturation phase occurs in the epididymis, where sperm...
Specific Heat
For example, increasing the temperature of one gram of water by 1°C requires one calorie of heat energy and can be written as 1 cal/g-°C, or...
Quantifying Heat
Heat Flow and Specific Heat
Heating and Cooling Curves
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...

