Tyrosine phosphorylation as evidence of epididymal cauda participation in the sperm maturation process of Corynorhinus mexicanus bat

Abstract

The bat Corynorhinus mexicanus provides an interesting experimental model for the study of epididymal sperm maturation because after spermatogenesis and the regression of the testes, this bat stores sperm in the epididymal cauda for several months. Earlier research conducted by our group suggested that sperm maturation in this species must be completed in the caudal region of the epididymis. One of the major signal transduction events during sperm maturation is the tyrosine phosphorylation of sperm proteins. The aim of the present study was to comparatively evaluate tyrosine phosphorylation in spermatozoa obtained from the caput, corpus and cauda of the epididymis during the sperm storage period. The maturation status of the sperm was determined by the percentage of capacitation and tyrosine phosphorylation in sperm obtained from the epididymis. The highest proportion of tyrosine phosphorylation was registered after the sperm had reached the cauda epididymis during the middle of the storage period. In conclusion, in Corynorhinus mexicanus and most likely in other chiropteran species with an asynchronous male reproductive pattern, epididymal sperm maturation ends in the caudal region of the epididymis and is related to the time that the sperm remains in the epididymis before mating activity.

Changes in membrane carbohydrates distribution associated to epididymal sperm maturation during the prolonged sperm storage period of Corynorhinus mexicanus bat (Chiroptera: Vespertilionidae)

“…All captures were done before the animals left their roost (12:00 -16:00 hours) using an expanded hand-net (Bioquip Tropic net). The adult category and the reproductive condition of the individuals included in this study were stablished in accordance with reports by León-Galván et al (2005), Cervantes et al (2008), and Rodríguez-Tobón et al (2016, taking into account the following variables: body weight, recorded using an Ohaus® (Ohaus Corporation, Parsippany, NJ, USA) portable electronic balance (±0.01 g); forearm length, measured with a vernier caliper (±0.1 mm); and by the external aspects of the sexual organs. A total of 26 bats were included in the study.…”

“…To extract of the sperm, every couple of epididymal regions were placed in 500 µL of Ringer at 37.8°C, finely minced and kept under agitation for 5 min to allow the spermatozoa to break free from the epididymal tubules. Subsequently, the minced material was collected with a Pasteur pipette and filtered by passage through a 20-µm-diameter-weft Lycra mesh (98% nylon/polyamide, 2% Lycra/elastane), and the fluid was collected in a 2 mL Eppendorf tube (Arenas-Ríos et al, 2005;Rodríguez-Tobón et al, 2016). The sperm suspension was washed by centrifugation at 500 g for 5 min; then, the supernatant was removed, and the cell pellet was re-suspended in 1 mL of Ringer.…”

“…In most of the studied species of mammals, the finish of epididymal maturation process occurs at the end of the corpus region of the epididymis. However, the seasonal bat Corynorhinus mexicanus (G. M. Allen, 1916) which is characterized by a long period of epididymal sperm storage (León-Galván et al, 2005), the sperm maturation culminate in the cauda region, probably as a time-dependent adaptation of the prolonged phase of sperm storage (Cervantes et al, 2008;Rodríguez-Tobón et al, 2016), what makes this mammalian species, an interesting model to study the changes in the distribution of carbohydrates present in the membrane of sperm. Therefore, the objective of this study was to analyze changes in the distribution of N-acetylglucosamine and/or sialic acid (NacG-AcS), Fucose (Fuc) and Mannose (Man) carbohydrates in the different domains of the membrane of sperm cells as they advance from the caput to the cauda of the epididymis in C. mexicanus.…”

Gamma GlutamylTranspeptidase Activity Determination in Epididymis of Corynorhinusmexicanus Bat Throughout Its Annual Cycle

“…However, it has been reported that, unlike other mammalian species in C. mexicanus, the epididymal sperm maturation ends in caudal region [24,35], showing that it is the month of October, the most important, as it was in that month, in which, an important tyrosine phosphorylation of protein in sperm increase, was detected [35], and it is from this date, that sperm were found with the ability of capacitation and to experience acrosome reaction [24,35].…”

Epididymal Sperm Maturation in Bats with Prolonged Sperm Storage

“…However, studies of tyrosine phosphorylation have been conducted mainly in species in which the sperm maturation process is seen to end before the spermatozoa enter the epididymal cauda. In the case of C. mexicanus, it has been determined that tyrosine phosphorylation increases in sperm obtained from the cauda [31], clearly indicating that the sperm maturation process continues there. And this finding, in turn, may be related to the time that the sperm are stored in the cauda.…”