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Prolonged epididymal sperm storage in vespertilionid and rhinolophid bats, provides an interesting experimental model for the study of spermatozoa epididymal maturation. We examined the presence of the cytoplasmic droplet, and the sequential induction of capacitation and the acrosome reaction in spermatozoa obtained from different epididymal regions (caput, corpus, cauda) throughout the annual reproductive cycle of Corynorhinus mexicanus (C. mexicanus). This is a vespertilionid bat that stores spermatozoa in the epididymis for several months after testes regression. The number of sperm recovered from the different epididymal regions indicate that epididymal transit in C. mexicanus is rapid. The persistence of a high percentage of sperm cells with cytoplasmic droplet in cauda epididymis was observed in addition to a low index of capacitation and acrosome reaction in sperm cells obtained from the corpus epididymis. There was a significant increase in the percentage of capacitated and acrosome reacted spermatozoa during the storage of sperm cells in the cauda epididymis and the percentage of capacitated spermatozoa was consistently, and significantly, higher (p0.05) in cauda compared to the corpus epididymis at all studied dates. The process of epididymal maturation in C. mexicanus is completed in the caudal region of this organ encompassing a significant period. Our results also indicate that in C. mexicanus, and in other vespertilionid and rhinolophid bats that show the same temporal asynchrony in the function of male reproductive organs, the final phases of epididymal maturation and storage are, apparently, independent of testicular function.

Prolonged sperm storage in the epididymis of Corynorhinus mexicanus bats after testicular regression has been associated with epididymal sperm maturation in the caudal region, although the precise factors linked with this phenomenon are unknown. The aim of this work is to determine the role of reactive oxygen species (ROS) and changes in antioxidant enzymatic activity occurring in the spermatozoa and epididymal fluid over time, in sperm maturation and storage in the caput, corpus and cauda of the bat epididymis. Our data showed that an increment in ROS production coincided with an increase in superoxide dismutase (SOD) activity in epididymal fluid and with a decrease in glutathione peroxidase (GPX) activity in the spermatozoa in at different time points and epididymal regions. The increase in ROS production was not associated with oxidative damage measured by lipid peroxidation. The results of the current study suggest the existence of a shift in the redox balance, which might be associated with sperm maturation and storage.

The mechanisms that concern DNA repair have been studied in the last years due to their consequences in cellular homeostasis. The diverse and damaging stimuli that affect DNA integrity, such as changes in the genetic sequence and modifications in gene expression, can disrupt the steady state of the cell and have serious repercussions to pathways that regulate apoptosis, senescence, and cancer. These altered pathways not only modify cellular and organism longevity, but quality of life (“health-span”). The DNA mismatch repair system (MMR) is highly conserved between species; its role is paramount in the preservation of DNA integrity, placing it as a necessary focal point in the study of pathways that prolong lifespan, aging, and disease. Here, we review different insights concerning the malfunction or absence of the DNA-MMR and its impact on cellular homeostasis. In particular, we will focus on DNA-MMR mechanisms regulated by known repair proteins MSH2, MSH6, PMS2, and MHL1, among others.

Epididymal sperm maturation is the process through which sperm acquire the potential to fertilize the egg. For most mammals, studies report that this process is completed before the sperm enter the cauda region of the epididymis; however, in some bat species, such as the Mexican big-eared bat (Corynorhinus mexicanus), this does not occur, as the process does not end until the sperm are inside the cauda of the epididymis, and thus is associated with a long storage period.

GGT initiates the degradation of both oxidized and reduced glutathione at the cell surface by cleaving the unique gamma glutamyl bond. The successive hydrolysis of oxidized or reduced CysGly by aminopeptidase or dipeptidase releases Gly, and cysteine/cysteine is recovered for intracellular synthesis of glutathione. In addition, GGT plays a major physiological role in providing cysteine to cells for GSH synthesis and protein synthesis, thereby playing a major role in antioxidant defense and normal growth. GGT is present in the epididymis, principally in caput. The catalytic activity of GGT is highest in the proximal epididymal regions and decreases toward the distal regions; participating in the epididymal sperm maturation process.In most mammals, epididymal sperm maturation takes place in a period not exceeding ten days, ending in the distal part of the corpus of the epididymis, before reaching the caudal region, which is responsible only for sperm storage; however, in C. mexicanus the epididymal sperm maturation ends in caudal epididymalregion.For this reason, the main goal of the present study was to determine the relationship between the GGT activity through the caput and caudal epididymal regions, throughout annual cycle of Corynorhinusmexicanus bat.We found that the GGT activity appears to be important for epididymal sperm maturation in C. mexicanus bat in cephalic region, and important for protection against ROS epididymal caudal region.

In Chihuahuan Desert arid zone, particularly the states of Zacatecas and San Luis Potosi, Mexico, have been distinguished by its large mining activity, however, many of these mines are disuse, becoming potential refuges for various species of cave bats. Monitoring the potential roosts by Corynorhinus townsendii was made within the system of mines in the vicinity of the Sierra La Mojonera Flora and Fauna Protection Area, at Mexico’s Central Highlands in the states of Zacatecas and San Luis Potosi. Which consisted of visual inspection inside, and mist netting at the entrance of different mines during an annual cycle. The main reproductive roosts for C. townsendii were identified. Spermatogenesis takes place during May-September; the mating period in November-December, whereas the sequence of gestation-lactation occurred since March to August of the next year. These data confirm that C. townsendii in the area of study follow a seasonally monoestrous reproductive pattern, characterized by an asynchrony between the ovarian and spermatogenic cycles.