Chromosomal analysis of the leptodactylids Pleurodema diplolistris and Physalaemus nattereri (Amphibia, Anura)

Detailed characterizations of the karyotypes of the Brazilian leptodactylid frogs Pleurodema diplolistris, the only species of Pleurodema not studied cytogenetically so far, and Physalaemus nattereri, a species in the Ph. biligonigerus group, are presented. Both karyotypes had 2n = 22 and their chromosomes had a very similar morphology, except for pair 11, which was metacentric in Pl. diplolistris and telocentric in Ph. nattereri. The localization of nucleolar organizer regions (NORs) and heterochromatic bands allowed the differentiation of chromosomes that were morphologically indistinguishable between these species, such as pairs 1, 3 and 10, which showed interstitial C-bands in Ph. nattereri, and pair 8, that had an NOR and an adjacent C-band in Pl. diplolistris. Pair 8 also has NOR-bearing chromosomes in many other Pleurodema species. However, in these species, the NOR is located proximal to the centromere on the short arm, while in Pl. diplolistris it occurred distally on the long arm, a condition that may be considered a derived state. In Ph. nattereri, the NOR occurred on chromosome I 1 and differed from the other species of the Ph. biligonigerus group. In contrast, C-banding revealed a heterochromatic block near the centromere on the short arm of pair 3, a characteristic common to all members of this group of Physalaemus.27448148

The in vitro effect of levonorgestrel on the acrosome reaction of human spermatozoa from fertile men

The objective of the study was to evaluate the effect of levonorgestrel (LNG) on the occurrence of acrosome reaction (AR) of capacitated spermatozoa from fertile men. A total of 20 semen samples from four fertile men were evaluated. The spermatozoa were separated by swim-up, and subsequently incubated for 20 h under capacitating conditions. Capacitated spermatozoa were exposed to three different concentrations of LNG (200, 400 and 800 ng/mL), follicular fluid (20% v/v), and ethanol or human tubal fluid medium (HTF) as a control. The AR rate and the ratio of live to dead spermatozoa were assessed after 15 and 30 min of incubation at 37degreesC and 5% CO2. The different treatments were compared with follicular fluid and HTF medium as positive and negative controls. The main results showed that the AR rate after 15 min of exposure was not affected by LNG and was significantly higher with follicular fluid than with all the other treatments. At 30 min of exposure, the three LNG concentrations induced a greater rate of AR than the HTF and a trend of higher AR rate with greater concentration was observed. Follicular fluid induced a significantly higher rate of AR than the other treatments. In conclusion, the addition of LNG in vitro to capacitated human spermatozoa is associated with a dose-dependent increased rate of AR, but such increase was not as Great that induced by follicular fluid. (C) 2003 Elsevier Inc. All rights reserved.681555

In vitro effect of levonorgestrel on sperm fertilizing capacity and mouse embryo development

The objectives of this study were to assess the expression Of alpha-D-mannose binding sites in human spermatozoa, human sperm-oocyte interaction and the development of early stages of mouse embryo in the presence of levonorgestrel (LNG). Semen samples were obtained from 16 normozoospermic men. Spermatozoa were separated by Percoll gradient and incubated overnight for capacitation. The kinetic analysis of the expression of alpha-D-mannose binding sites was determined at 0, 4 and 22 h and in 22 h-capacitated spermatozoa that had been exposed to 1, 10 or 100 ng/mL of LNG or to a control medium for 30 min. Sperm binding sites for alpha-D-mannose were detected using commercial alpha-D-mannosylated bovine serum albumin conjugated with fluorescein isothiocyanate. To evaluate sperm-oocyte interaction, each oocyte was placed in a 100-mu L droplet containing one of the three doses of LNG or control medium and inseminated with 1.0X10(5) Motile spermatozoa/mL, after which the number of bound spermatozoa was evaluated. A total of 157 two-cell embryos recovered from eight mice was pooled and assigned randomly to treatment (1, 10 or 100 ng/mL of LNG) or control groups. There was a significant increase in the expression of specific alpha-D-mannose binding sites (Patterns II and III) during the incubation of spermatozoa under capacitating conditions. In the presence of LNG, results showed that there was no significant difference in the expression of specific alpha-D-mannose binding sites (Patterns II and III) at any LNG concentration tested compared with those spermatozoa in control medium. None of the LNG concentrations were capable of modifying the number of spermatozoa tightly bound to the human zona pellucida. There was no association between the presence or absence of LNG or the different doses of LNG evaluated and mouse embryo development. In conclusion, the hypothesis that in vitro exposure to LNG could interfere with sperm function and could contribute to the mechanism of action of this form of contraception was not confirmed but cannot be ruled out by the results of this study. (C) 2005 Elsevier Inc. All rights reserved.721717

In vivo assessment of the human sperm acrosome reaction and the expression of glycodelin-A in human endometrium after levonorgestrel-emergency contraceptive pill administration

BACKGROUND: The objectives were firstly to assess acrosome reaction (AR) status of spermatozoa following uterine flushing, secondly to measure levonorgestrel (LNG) levels in serum and in uterine flushing fluid and finally to measure endometrial glycodelin-A expression after administration of LNG as a form of emergency contraception (EC). METHODS: Forty-eight experiments were conducted on 15 regularly menstruating women. Four groups were formed based on different intercourse to treatment interval and treatment to recovery of spermatozoa and the biopsies. RESULTS: Twenty-four and forty-eight hours after treatment, there were 14.5 +/- 3.9 x 106 and 17.3 +/- 6.8 x 106 sperm recovered from the uterus, respectively. There were no differences between the AR rate and the endometrial glycodelin-A staining intensity in an LNG or placebo treated cycles. The LNG in uterine flushing medium represented 1.38% of the values observed in serum 24 h after the LNG intake. CONCLUSIONS: Twenty-four and forty-eight hours after administration of EC, neither the proportion of AR sperm, nor the glycodelin-A level was influenced by 1.5 mg of LNG. LNG did not impair the cervical mucus either because viable spermatozoa were found in the genital tract 36-60 h after coitus and 24-48 h after LNG intake. The mechanism of action of LNG as EC remains unknown.2282190219