A comparative study of spermatozoal chromatin using acridine orange staining and flow cytometry

Acute exposure to isoflurane impairs sperm parameters in mice

Isoflurane, an inhalational anesthetic from the halogenated group, has been increasingly used in the medical and scientific fields. Due to its characteristics, it is capable of inducing anesthesia quickly and quietly; however, the adverse effects resulting from its use have not yet been fully elucidated, especially with regard to reproductive aspects. Considering its common use in research laboratories, whether for performing surgical procedures or for prior exposure to euthanasia, knowledge about its interference in sperm parameters of experimental models characterizes an important study goal. The aim of the present study was to determine the interference of acute exposure to isoflurane on the sperm quality of mice, both immediately previous to euthanasia and in later evaluation, twenty days after a single anesthetic exposure. Our results demonstrate that acute anesthetic exposure reduces sperm motility and is responsible for the formation of damaged sperm cells that are prone to apoptosis, which may affect the outcome of reproductive experiments even 20 days after exposure.

Assessment of different sperm functional tests in golden-headed lion tamarins (Leontopithecus chrysomelas)

The golden-headed lion tamarin (Leontopithecus chrysomelas) is an endangered species endemic to Brazil's Atlantic Forest, a shrinking biodiversity hotspot. As in other Neotropical primates, its semen characteristics and freezability are poorly studied. Hence, reproductive technologies for callitrichids would greatly benefit from reliable methods of semen analysis. In a bid to promote reproductive research in tamarins, we validated simple and inexpensive sperm function tests that can be used to monitor sperm-egg binding, plasma membrane and acrosome integrity, mitochondrial activity, and DNA fragmentation. Ejaculates from adult males were individually diluted and divided into control and damage-induced aliquots, and then samples comprising assorted amounts of damaged spermatozoa were examined by organelle-specific tests. Our findings showed that sperm-binding in chicken egg perivitelline membrane (EPM) positively correlated with the number of spermatozoa injured by snap-freezing. Eosin-nigrosin (EN) and propidium iodide readings were correlated with each other, and both provided robust measurements of plasma membrane integrity. A high correlation between expected and measured amounts of acrosome-intact spermatozoa was found using Fast Green-Rose Bengal (FG-RB), Coomassie Blue (CB), and FITC-PSA stains, and all three methods exhibited comparable results. Likewise, different percentages of UV-irradiated spermatozoa were accurately assessed for DNA integrity by Toluidine Blue (TB) and sperm chromatin dispersion (SCD) tests. Comparisons between 3,3'-diaminobenzidine (DAB) and JC-1 stains also indicated the reliability of the former assay to ascertain gradual increases in spermatozoa with greater mitochondrial function. These data confirmed that different parts of the tamarin spermatozoa can be simply and consistently evaluated by EPM, EN, FG-RB, CB, TB, and DAB protocols.

The role of amides in seminal cryopreservation of wild silverside, Odontesthes bonariensis

Amides were tested as internal cryoprotectants for the preservation of wild silverside (Odontesthes bonariensis) sperm. The semen was diluted in modified Mounib's medium and cryopreserved by adding 2, 5, 8 or 11% of dimethyl acetamide (DMA), dimethyl formamide (DMF) or methyl formamide (MF). Dimethyl sulfoxide (DMSO) at a concentration of 10% diluted in modified Mounib's medium was used as a control. The rate motility (17.7 ± 1.9%) and time motility (143.2 ± 9.7 s) (P < 0.05) of the sperm were higher with 2% DMF when compared with the other treatments. Despite the better motility results obtained with 2% DMF, the solution was not able to maintain cellular structure integrity of the cryopreserved sperm. The 10% DMSO and 8% MF treatment allowed for completeness of the plasma membrane (34.8% and 29%), functional mitochondria (19.8% and 16.2%) and plasma membrane fluidity (39.4% and 46.4%); furthermore, rate motility (11.8% and 10%) and time motility (81.4 s and 71.8 s) of the sperm were found to be at suitable levels when compared with 2% DMF. Thus, our evaluation suggests that 10% DMSO and 8% MF provide better cryopreservation of O. bonariensis sperm cells.