Miguel Ángel León-Galván

MALE REPRODUCTIVE CYCLE OF MEXICAN BIG-EARED BATS, CORYNORHINUS MEXICANUS (CHIROPTERA: VESPERTILIONIDAE)

Abstract Morphological observations of male genital tracts obtained from wild, adult Mexican big-eared bats (Corynorhinus mexicanus) revealed only one but long annual reproductive cycle showing the existence of temporal asynchrony of its reproductive functions, as is characteristic of temperate-zone vespertilionid and rhinolophid chiropterans. Testes were largest in August, whereas maximum development of epididymides and accessory sex glands complex was observed 1 and 3 months later. High value of relative body condition of individuals was observed from May to June, when testicular enlargement commenced, suggesting that recrudescence of spermatogenesis in the adult bats is dependent on a good body condition.

Echolocation calls and a noteworthy record of Pteronotus gymnonotus (Chiroptera, Mormoopidae) from Tabasco, Mexico

Echolocation calls of the big naked-backed bat, Pteronotus gymnonotus, are poorly known. At present, only the predominant frequencies have been described from calls emitted by indoor or hand held specimens (Griffin and Novick, 1955; Grinnell, 1970; Simmons, 1973) and a single sonogram (Pye, 1980). We present the first description of echolocation characteristics of P gymnonotus, recorded from a freeflying specimen from Tabasco, Mexico. Distributional implications of this record also are discussed.

DNA Mismatch Repair System: Repercussions in Cellular Homeostasis and Relationship with Aging

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.

DNA MMR systems, microsatellite instability and antioxidant activity variations in two species of wild bats: Myotis velifer and Desmodus rotundus, as possible factors associated with longevity

The accumulation of oxidative damage to biomolecules, such as DNA, is known to induce alterations in the cells mechanisms and structure that might lead to the aging process. DNA mismatch repair system (MMR) corrects base mismatches generated during DNA replication that have escaped the proofreading process. In addition, antioxidant enzymes can reduce reactive oxygen species effects in order to protect cells from oxidizing damage. In order to determine the importance of these associated factors during the aging process, in this study, levels of MMR proteins MSH2 and MLH1, as well as microsatellite markers, were compared in liver, lung, and brain of juvenile, adult, and old, both female and male, individuals from two species of wild bats: the short-lived Myotis velifer and the longer lived Desmodus rotundus. Catalase, glutathione peroxidase, and superoxide dismutase were also analyzed to determine if the antioxidant protection correlates negatively with DNA damage. Antioxidant activities were higher in the longer lived D. rotundus than in M. velifer. Furthermore, old M. velifer but not old D. rotundus bats had reduced MMR levels and increased microsatellite instability. Therefore, although our results correlate the reduced MMR efficiency, the deficient antioxidant activity, and the increase in DNA damage with the aging process, this is not always true for all living organisms.

Serotonin in Testes of Bat Myotis velifer During Annual Reproductive Cycle: Expression, Localization, and Content Variations

The mechanism of reproduction in mammals is very complex and in some cases is quite particular. For example in some bat species, the male presents a reproductive mechanism characterized by an annual testicular cycle that goes from recrudescence to regression (spermatogenesis to inactivity period, respectively). After recrudescence, the spermatozoa arrive at epididymis and wait to be expelled at the time of ejaculation during the mating period, which occurs some months later. Because serotonin (5-HT) has gained reproductive importance in the last years, the aim of the present study was to analyze the expression of this indolamine and both tryptophan hydroxylase and monoamine oxidase isoform A-enzymes involved in its metabolism-in Myotis velifer testes, a seasonal reproductive bat species that shows temporal asynchrony in its sexual cycle, across the principal periods of their reproductive cycle. By using both Falck-Hillarp histochemistry and immunofluorescence techniques, we found serotonin in vesicles of Leydig cells and probably Sertoli cells too; interestingly, both intracellular localization and concentration was variable across the different stages of the reproductive cycle, being lower during spermatogenesis phase and increasing during the mating phase. These results suggest that 5-HT is present in bat testes and it could play an important role in testicular function during their reproductive cycle.