Decline In Sperm Viability Research Articles

End of the Season Blues: Senescence and Reproductive Trade-Offs in Male Scorpions

Seasonal reproductive dynamics and senescence have profound impacts on male fertility, yet these processes remain understudied in scorpions. This study investigates how reproductive parameters—such as testicular mass, sperm quantity, and viability—change over the course of the reproductive season in Urophonius achalensis males. We found that early-season males exhibited higher sperm quality and testicular mass compared to their older counterparts, suggesting that senescence, rather than reproductive effort, drives the decline in sperm viability. Interestingly, isolated males accumulated more sperm without a reduction in viability, highlighting potential mechanisms that preserve sperm quality despite senescence. Body condition also played a key role, with males in better condition showing higher sperm counts but facing a sharper decline in sperm viability as the season progressed, suggesting trade-offs between early reproductive success and later-life reproductive costs. Our findings offer novel insights into the reproductive strategies of scorpions, emphasizing the interplay between senescence, environmental stressors, and reproductive investment. This work provides new insights into the reproductive biology of scorpions, with broader implications for understanding the role of senescence and mating systems in shaping reproductive strategies.

Influence of Storage Time on the DNA Integrity and Viability of Spermatozoa of the Spider Crab Maja brachydactyla.

Natural populations of the spider crab Maja brachydactyla constitute a fishery resource of great economic importance in many countries. As in the rest of eubrachyurans, the females of this species have ventral-type seminal receptacles where they store sperm from copulations. Sperm can be stored in these structures for months and even years before egg fertilisation, with the consequent degradation of the sperm cells during the time. In this work, we analyse the viability and the possible genetic damage in sperm accumulated in the seminal receptacles of M. brachydactyla females as a function of the storage time (from 0 to 14 months) using the comet assay technique. On one hand, we developed an algorithm for comet image analysis that improves the comet segmentation compared with the free software Open comet v1.3.1 (97% vs. 76% of detection). In addition, our software allows the manual modification of the contours wrongly delimited via the automatic tool. On the other hand, our data show a sharp decline in sperm viability and DNA integrity in the first four months of storage, which could lead to a decrease in the fecundity rate and/or viability of the embryos or larvae from the second and third clutches of the annual cycle if the repair capacity in these gametic cells is low.

Polymyxin B neutralizes endotoxin and improves the quality of chicken semen during liquid storage

Despite its importance in gamete utilization for livestock production, poultry semen cryopreservation in a liquid state, is limited in the poultry industry due to a significant decline in sperm viability and functionality during liquid storage. Lipopolysaccharide (LPS) is released from gram-negative bacteria and impairs sperm function in mammals. Using exogeneous LPS, we show this endotoxin compromises sperm viability and function, including motility and penetrability to the inner peri-vitelline layer (IPVL) during liquid storage at 4 °C. This outcome was supported by LPS quantification showing an extreme increase in the first 24 h of storage. Polymyxin B (PMB) is an LPS neutralizer previously shown to improve fertility in boar semen, thus we explored the effect of PMB on chicken semen quality during liquid storage. Sperm viability and penetrability tests showed that PMB completely abolishes the deleterious effect by LPS. However, co-addition of PMB with penicillin G (PenG), an antibiotic against gram positive bacteria, reduces IPVL-penetrability while improving sperm viability post-storage. Furthermore, artificial insemination trials showed that PMB addition improves semen fertility at the post liquid storage. Our results show that chicken semen quality during liquid storage is impaired by bacterial LPS, but improved by PMB addition due to cancelled endotoxic effects, which offers a new approach for prolonged fertility of poultry semen storage in a liquid state.

The Effects of Olive Leaf Extract on The Testis, Sperm Quality and Testicular Germ Cell Apoptosis in Male Rats Exposed to Busulfan.

BackgroundBusulfan (BU) has a destructive effect on the male reproductive system. The goal of this study was to assess the effects of olive leaf extract (OLE) as a source of antioxidants and phenolic compounds, on BU-induced damages in rat testes.Materials and MethodsIn this experimental study, 40 male Wistar rats were randomly divided into 5 groups. The control group (CTL) received a single intraperitoneal (i.p.) injection of dimethyl sulfoxide (DMSO), followed by oral administration of distilled water for 5 weeks. In BU group, BU (10 mg/kg) was administrated i.p. once. In co- treatment groups, first, received BU (10 mg/kg, a single i.p. injection) then, OLE was administrated orally at different doses of 250 mg/kg (BU+OLE 250), 500 mg/kg (BU+OLE 500) and 750 mg/kg (BU+OLE 750), for 5 weeks. Next, blood and sperm samples were collected. The left testis was removed to investigate testicular parameters and apop- tosis by using H&E and TUNEL staining, respectively. All data were analyzed by SPSS software and a P<0.05 was considered significant.ResultsThere was a significant decline in sperm viability (P=0.017), number of primary spermatocyte (PS) (P=0.001) and Leydig cells (P=0.023) in the BU group versus the CTL group. OLE at three doses could repair these defects ver- sus BU group. Increases in apoptotic spermatogonia cells (SG) due to BU were significantly reduced by OLE 250 and 500 mg/kg (P<0.01). A reduction in germinal epithelium height and an increase in apoptotic SG were observed in BU+OLE 750 group vs. other groups (P<0.01) and alkaline phosphatase (ALP) was at the highest level, also Aspartate aminotransferase (AST) increased markedly vs. CTL (P=0.024).ConclusionOral administration of OLE at the doses of 250 and 500 mg/kg could be helpful in ameliorating BU- induced toxicity in rat testes, while OLE 750 mg/kg not only did not cause positive effects, but also could exacerbate the harmful effects.

More Pitfalls with Sperm Viability Staining and a Viability-Based Stress Test to Characterize Sperm Quality

Sperm viability (SV) is a widely applied measure of sperm quality but our review of the ecological literature revealed that previously identified methodological pitfalls have not been overcome, including low cross-study standardisation of protocols, inadequate statistical treatment, and unaccounted for within-sample heterogeneity. SV is additionally affected by biological variation such as between species, reproductive organs, or sperm age cohorts. Using SV per se as a surrogate for sperm quality may, therefore, be problematic. Sperm viability (SV), the proportion of live sperm in a sample, is a widely applied measure of sperm quality but few studies test its robustness. At least three reasons make SV problematic as a surrogate for sperm quality. First, reviewing the ecological literature revealed that previously identified methodological pitfalls have not been overcome, including low cross-study standardisation of protocols, inadequate statistical treatment, and unaccounted for within-sample heterogeneity. Second, SV is affected by biological variation such as between species, reproductive organs, or sperm age cohorts. Third, the proportion of live sperm extracted from males appears more related to male than to sperm quality in the sense of the future performance of sperm. We propose an alternative method to assess sperm quality by characterising the temporal decrease of SV in a stressor medium and illustrate in two species, the common bedbug (Cimex lectularius) and the fruit fly (Drosophila melanogaster) how some common methodological pitfalls may be circumvented. Our data empirically support the well-known but little-considered facts that i) non-blind measurements alter SV and ii) that SV frequently have non-significant repeatability within one sample. iii) Cross-sectional sampling of ejaculates showed that this heterogeneity even masked a biological pattern - the sperm stratification within males. We show iv) that this shortcoming can be overcome by following the temporal decline of SV of a sperm subsample in a stress test. To measure sperm quality, we advocate analysing the temporal decline in SV in a stressor medium over current protocols that use SV per se and blinding samples for SV measurements. As cell viability is widely used in biological and medical laboratory studies, our protocol may be useful to characterise cell quality beyond

Silver nanoparticle induced toxicity to human sperm by increasing ROS(reactive oxygen species) production and DNA damage

Silver nanoparticles (AgNPs) have been used in medical products and industrial coatings, due to their antimicrobial properties. Excessive use of AgNPs can have adverse effects on the human body, however, their toxicity characteristics to human sperm and the potential mechanisms are not entirely clear. In this study, we exposed human sperm to different doses of AgNPs (0, 50μgml−1, 100μgml−1, 200μgml−1 or 400μgml−1) for various times (15min, 30min, or 60min), followed by analyses of the sperm viability, motility and the ratio of abnormal to normal sperm.Then, transmission electron microscopy(TEM) was used to explore the sperm ultrastructural characteristics. Reactive oxygen species production and DNA fragmentation were tested using standard kits and the sperm chromatin dispersion method, respectively. The results showed a dose- and time-dependent decline in sperm viability and motility and an increased ratio of abnormal to normal sperm after 30min and 60min of exposure to AgNPs at 200μgml−1 and 400μgml−1. The most common abnormalities were sperm heads with disrupted chromatin or absent acrosomes, bent tails, and curved mid-pieces. The ultrastructural characteristics of AgNP-treated sperm included disrupted, swollen, granular and vacuolar defects of the chromatin. In addition, ROS(reactive oxygen species)production and DNA fragmentation were markedly increased after 60min of exposure to AgNPs at 200μgml−1 and 400μgml−1. Our results indicated that AgNPs caused detrimental changes in human sperm characteristics, and the excessive use of AgNPs should be carried out with caution.

Ovarian Fluid Mediates the Temporal Decline in Sperm Viability in a Fish with Sperm Storage

A loss of sperm viability and functionality during sperm transfer and storage within the female reproductive tract can have important fitness implications by disrupting fertilization and impairing offspring development and survival. Consequently, mechanisms that mitigate the temporal decline in sperm function are likely to be important targets of selection. In many species, ovarian fluid is known to regulate and maintain sperm quality. In this paper, we use the guppy Poecilia reticulata, a highly polyandrous freshwater fish exhibiting internal fertilization and sperm storage, to determine whether ovarian fluid (OF) influences the decline in sperm viability (the proportion of live sperm in the ejaculate) over time and whether any observed effects depend on male sexual ornamentation. To address these questions we used a paired experimental design in which ejaculates from individual males were tested in vitro both in presence and absence of OF. Our results revealed that the temporal decline in sperm viability was significantly reduced in the presence of OF compared to a saline control. This finding raises the intriguing possibility that OF may play a role in mediating the decline in sperm quality due to the deleterious effects of sperm ageing, although other possible explanations for this observation are discussed. Interestingly, we also show that the age-related decline in sperm viability was contingent on male sexual ornamentation; males with relatively high levels of iridescence (indicating higher sexual attractiveness) exhibited a more pronounced decline in sperm viability over time than their less ornamented counterparts. This latter finding offers possible insights into the functional basis for the previously observed trade-off between these key components of pre- and postcopulatory sexual selection.

Effects of frequency of semen collection on quantitative and qualitative characteristics of semen in turkey breeder males

The effects of various frequencies of semen collection on several quantitative and qualitative semen characteristics were investigated in adult turkey breeder males (30 to 40 wk of age). In Experiment 1, a total of 35 males were first trained for semen collection (twice a week for 2 consecutive wk), and then divided into five groups (seven males each), each group being collected either once every 2 wk, once every week, twice every week, three times every week (each for 4 wk) or five to seven times per week (each for 2 wk). Volume, sperm concentration, and sperm number per ejaculate were determined for each ejaculate. No significant differences between groups were observed for sperm concentration (P > 0.05), but males collected once every 2 wk, once per week, or twice per week had larger volumes than males collected at higher frequencies (P < 0.05). Thus there were significant differences for sperm number per ejaculate between groups (P < 0.05). Also, daily semen output (DSO) was markedly increased in males collected at the highest frequencies (e.g., DSO = 0.62 x 10(9) and 1.93 x 10(9) in males collected once and five times per week). Finally, in euthanatized birds (36 wk) no differences between groups were observed for body weight (25.8 +/- 1.7 kg), testicular weight (51.5 +/- 2.2 g), or total number of elongated spermatids per male (14.0 +/- 0.8 x 10(9)). In Experiment 2, 35 males were distributed into groups and collected under the same conditions as in Experiment 1. Besides quantitative analyses of ejaculates (volume, sperm concentration, and sperm per ejaculate), sperm viability between groups was also tested using the Sybr14/PI fluorescence test. Our results demonstrated: 1) a favorable effect of high semen collection frequencies on sperm viability and, 2) a marked decline in sperm viability during the first 2 d following a 2-d resting period in males collected five times a week. We concluded that turkey males express their optimal reproductive capacity more efficiently when semen collection is undertaken at a high rather than a low frequency.

Chemical Mediation of Sperm Activity and Longevity in the Solitary Ascidians Ciona intestinalis and Ascidiella aspersa.

Sperm chemotaxis to compounds originating from eggs is common in solitary ascidians. This chemotactic response is associated with an increase in the activity level of the sperm. Here we examine the hypothesis that the period of sperm viability is reduced by the stimulation of increased activity by compounds associated with the eggs of solitary ascidians. The activity level and longevity of sperm from two species of solitary ascidian, Ciona intestinalis and Ascidiella aspersa, were measured after incubation in water that had been stored with homospecific eggs. Our results showed that the proportion of active sperm increased in homospecific egg water. This increase corresponded to a sharp decline in sperm longevity, which suggests a causal link between sperm activity and longevity. We suggest that sperm energy reserves are conserved in the absence of compounds associated with homospecific eggs, and that this may have significant ecological consequences for these organisms. Cross-reactivity in the chemotactic response of sperm from one species to the chemoattractant of another is common in ascidians, and increased sperm activity is associated with this response. Therefore, we investigated cross-reactivity in the activation of C. intestinalis and A. aspersa sperm to heterospecific egg water. Our results showed that A. aspersa sperm were activated by the egg water of C. intestinalis, resulting in a decline in sperm viability, but that this response was not reciprocated between the sperm of A. aspersa and the egg water of C. intestinalis. This suggests either that sperm of A. aspersa respond to compounds associated with the eggs with a higher degree of specificity than C. intestinalis sperm, or that compounds associated with A. aspersa eggs have more generalized activity than those of C. intestinalis.