Acrosome reaction of fowl sperm: evidence for shedding of the acrosomal cap in intact form to release acrosomal enzyme

Zinc mitigates cadmium-induced sperm dysfunction through regulating Ca2+ and metallothionein expression in the freshwater crab Sinopotamon henanense

Cadmium (Cd) is a highly toxic heavy metal element that might adversely affect sperm function such as the acrosome reaction (AR). Although it is widely recognized that zinc (Zn) plays a crucial role in sperm quality, the complete elucidation of how Zn ameliorates Cd-induced sperm dysfunction is still unclear. In this study, we aimed to explore the protective effects of Zn against the sperm dysfunction induced by Cd in the freshwater crab Sinopotamon henanense. The results demonstrated that Cd exposure not only impaired the sperm ultrastructure, but also caused sperm dysfunction by decreasing the AR induction rate, acrosome enzyme activity, and Ca2+ content in sperm while elevating the activity and transcription expression of key Ca2+ signaling pathway-related proteins Calmodulin (CAM) and Ca2+-ATPase. However, the administration of Zn was found to alleviate Cd-induced sperm morphological and functional disorders by increasing the activity and transcription levels of CaM and Ca2+-ATPase, thereby regulating intracellular Ca2+ homeostasis and reversing the decrease in Ca2+ contents caused by Cd. Furthermore, this study was the first to investigate the distribution of metallothionein (MT) in the AR of S. henanense, and it was found that Zn can reduce the elevated levels of MT in crabs caused by Cd, demonstrating the significance of Zn in inducing MT to participate in the AR process and in metal detoxification in S. henanense. These findings offer novel perspectives and substantiation regarding the utilization of Zn as a protective agent against Cd-induced toxicity and hold significant practical implications for mitigating Cd-induced sperm dysfunction.

p53 Protein Evaluation on Spermatozoa DNA in Fertile and Infertile Males

Introduction and Objectives:

Protein p53 role in the spermatogenesis is demonstrated, it guarantees both the appropriate quality and quantity of mature spermatozoa. In this observational study we evaluate the eventual correlation between “corrected” p53 concentration on human spermatozoa DNA and male fertility potential.

Materials and Methods:

Our work is based on an observational study made of 169 male in a period between March 2012 and February 2017. The entire study group is composed by 208 male partners aged between 26-38 years with ejaculate volume from 0.6 to 5.8 mL and heterogeneous seminal valuation: 86/208 (41,3%) normospermic; 19/208 (9,1%) mild oligospermic; 51/208 (24,5%) moderate oligospermic to; 52/208 (25,1%) with severe oligospermic. The “control” group A includes 39 male partners considered “fertile”, because we did the p53 “corrected” test on their spermatozoa after 28 ± 3,5 days from the positives of their partners pregnancy test (betaHCG> 400 m U/m L). The group B, subdivided in B1, B2 and B3, includes 169 male partners for a observational period of 60 months. This partners don't report previous conceptions, they aren't smokers, don't make use neither of alcohol nor drugs and don't present pathologic varicocele studied with ecoColorDoppler. They are all married or stable cohabitants from a period of 27-39 months and report to have frequent sex without protection with their partners. Determination of p53 procedure: To separate the spermatozoa from seminal fluid we utilized the Differex™ kit System and the DNA IQ™ kit (Promega). For the p53 test we used the direct DuoSet IC kit and quantitative (R&D System). The p53 values were corrected in respect to the spermatozoa concentration expressed in ng/millions of spermatozoa.

Results:

Group A (39 male) presents “correct” p53 values that vary from 0.35 to 3.20 ng/millions of spermatozoa and group B presents values that vary from 0.68 to 14.53. From group B (48 male) in the observational period we have recorded 21 pregnancies with initial “correct” p53 values that vary from a minimum of 0.84 to a maximum of 3.29. In the subgroup B1 we obtained 8 pregnancies from male partners with a “correct” p53 concentration included between 0.84 to 1.34. In the subgroup B2 we obtained 13 pregnancies from male partners with a “correct” p53 concentration included between 1.66 and 3.29. In the subgroup B3 (121 male) there weren't neither pregnancies nor miscarriages and “correct” p53 values were included between 3.58 and 14.53.

Conclusion:

The results show that the member of the group A with values of 'corrected' p53 between 0.35 and 3.20 were considered “Fertile”, although in the observational period 3 miscarriages happened for 3 partners. 36 partners on 39 (92,3%) had a p53 concentration inferior to 1.65, this value were considered as the extreme to identify this group. The member of the group B1 had “corrected” p53 concentration that were included in the group. In the group B2 were observe 13 pregnancies, so its member were considered “potentially fertile” In the group B3 (121 male) weren't observe neither pregnancies nor miscarriages, so its member were considered “potentially infertile”. If further studies confirm these data, we will consider the p53 test ELISA inspected in “correct” p53 as a new and accurate marker of the potential of male fertility.

Peanut agglutinin specifically binds to a sperm region between the nucleus and mitochondria in tunicates and sea urchins

Peanut agglutinin (PNA) is an established marker of the mammalian acrosome. However, we observed that PNA specifically binds to a unique intracellular structure alongside the nucleus in ascidian sperm. Here, we characterize the PNA-binding structure in sperm of marine invertebrates. PNA bound to the region between the mitochondrion and nucleus in spermatozoa of ascidians, sea urchins, and an appendicularian. However, PNA-binding substances were not exposed by the calcium ionophore ionomycin in three ascidian species, indicating that it is a distinct structure from the acrosome. Instead, the ascidian PNA-binding region was shed with the mitochondrion from the sperm head via an ionomycin-induced sperm reaction. The ascidian PNA-binding substance appeared to be solubilized with SDS, but not Triton X-100, describing its detergent resistance. Lectins, PHA-L₄ , SSA, and MAL-I were detected at an area similar to the PNA-binding region, suggesting that it contains a variety of glycans. The location and some of the components of the PNA-binding region were similar to known endoplasmic reticulum (ER)-derived structures, although the ER marker concanavalin A accumulated at an area adjacent to but not overlapping the PNA-binding region. Therefore, we conclude that ascidian sperm possess a non-acrosomal, Triton-resistant, glycan-rich intracellular structure that may play a general role in reproduction of tunicates and sea urchins given its presence across a wide taxonomic range.

Impact of induced levels of specific free radicals and malondialdehyde on chicken semen quality and fertility

Over the past decades, scientists endeavored to comprehend oxidative stress in poultry spermatozoa and its relationship with fertilizing ability, lipid peroxidation (LPO), free-radical scavenging systems, and antioxidant therapy. Although considerable progress has been made, further improvement is needed in understanding how specific reactive oxygen species (ROS) and malondialdehyde (MDA, a toxic byproduct of LPO) disrupt organelles in avian spermatozoon. Hence, this study examined functional changes in chicken spermatozoa after incubation with different ROS, and their implications for the fertility. First, semen samples from 14 roosters were individually diluted and aliquoted into five equal parts: control, superoxide anion, hydrogen peroxide (H₂O₂), hydroxyl radicals, and MDA. After incubation with these molecules, aliquots were analyzed for motility, plasma membrane and acrosome integrity, mitochondrial activity, and LPO and DNA damage. Hydrogen peroxide was more detrimental for sperm motility than hydroxyl radicals, whereas the superoxide anion and MDA exhibited no differences compared with controls. In turn, plasma membrane and acrosome integrity, mitochondrial activity, LPO and DNA integrity rates were only affected by hydroxyl radicals. Thereafter, semen aliquots were incubated under the same conditions and used for artificial insemination. In accordance to our in vitro observations, H₂O₂ and hydroxyl radicals sharply reduced egg fertility, whereas superoxide anion and MDA only induced slight declines. Thus, chicken sperm function was severely impaired by H₂O₂ and hydroxyl radicals, but their mechanisms of action seemingly comprise different pathways. Further analysis regarding susceptibility of spermatozoon organelles to specific radicals in other poultry will help us to understand the development of interspecific differences in scavenging systems and to outline more oriented antioxidant approaches.

Organization of Membrane Rafts in Chicken Sperm

Being transcriptionally and translationally inactive, sperm must utilize preassembled pathways into specific compartments in which they function to fertilize ovum. Membrane rafts are specific membrane regions enriched in sterols and glycosphingolipids such as ganglioside G_M1 (G_M1) and play an important role in a variety of cellular functions. Recent findings have demonstrated that membrane rafts are present in mammalian sperm and are involved in regulating the induction of acrosome exocytosis. However, no information is available on whether avian sperm possess membrane rafts. Thus, we investigated the organization of membrane rafts in chicken sperm. Our localization experiments for G_M1 and sterols showed that the plasma membrane overlaying the sperm head possesses specific membrane domains enriched in both aforementioned lipids. Caveolin-1, which localizes into membrane rafts in other systems, was localized only to the sperm tail. Based on the biochemical definition that membrane rafts are insoluble membranes when subjected to a Triton X-100 treatment, we isolated detergent-insoluble membranes from chicken sperm and quantified the G_M1 content, which showed an enrichment of G_M1 in the membrane fraction relative to the detergent-soluble fraction. Together with the results of localization and biochemical experiments, we demonstrate for the first time that membrane rafts exist in chicken sperm. Thus, our results provide a foundation for investigating a novel cellular pathway inherent in avian sperm membranes that might be involved in functions necessary to achieve fertilization.