Articoli di riviste: "Spermatozoa Physiology"

1

Aitken, RJ. "Free radicals, lipid peroxidation and sperm function". Reproduction, Fertility and Development 7, n. 4 (1995): 659. http://dx.doi.org/10.1071/rd9950659.

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The cellular generation of reactive oxygen species was first observed in mammalian spermatozoa in the late 1940s. The field then remained dormant for 30 years until Thaddeus Mann and Roy Jones published a series of landmark papers in the 1970s in which the importance of lipid peroxidation as a mechanism for damaging mammalian spermatozoa was first intimated. The subsequent demonstration that human spermatozoa produce reactive oxygen species and are susceptible to peroxidative damage has triggered intense interest in the role of oxidative stress in the aetiology of male infertility. Moreover, data have recently been obtained to indicate that, although excessive exposure to reactive oxygen species may be harmful to spermatozoa, in physiological amounts these molecules are of importance in the control of normal sperm function. This review considers the dualistic role of reactive oxygen species and sets out the current understanding of the importance of oxidative processes in both the physiology and the pathology of the human spermatozoon. Extra keywords: human spermatozoa, reactive oxygen species.

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Ishijima, S., M. S. Hamaguchi, M. Naruse, S. A. Ishijima e Y. Hamaguchi. "Rotational movement of a spermatozoon around its long axis". Journal of Experimental Biology 163, n. 1 (1 febbraio 1992): 15–31. http://dx.doi.org/10.1242/jeb.163.1.15.

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The rotational movement of a spermatozoon around its longitudinal axis was investigated by two methods: by observing a spermatozoon attached vertically to a coverslip by the tip of its head, and by observing a spermatozoon freely swimming in a medium by means of ‘double-focal microscopy’, which yielded simultaneous images at two different focal planes. Similar results were obtained by these two methods. Sea urchin, starfish, medaka, human, golden hamster and bull spermatozoa rolled in both clockwise and counterclockwise directions, although there was a large difference in the proportion of spermatozoa rolling in each direction in the different species. The majority of sea urchin and starfish spermatozoa rolled in a clockwise direction when an observer viewed the cell from its anterior end, whereas the majority of medaka, golden hamster, human and bull spermatozoa rolled in a counterclockwise direction relative to the same observer. Moreover, some spermatozoa occasionally changed their rotational direction. These results suggest that the mechanism regulating the direction of rotation of the spermatozoa is lax. As rotational movement of a spermatozoon around its longitudinal axis is due to the three-dimensional component of the beat of the flagellum, the direction of the three-dimensional movement presumably changes as the spermatozoa swim.

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3

Rajalakshmi, M. "Physiology of the epididymis and spermatozoa". Journal of Biosciences 7, n. 2 (marzo 1985): 191–95. http://dx.doi.org/10.1007/bf02703587.

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4

Seubparu, Lucksanaveejit, Mingkwan Nipitwathanaphon, Wijit Wisoram, David Merritt e Lertluk Ngernsiri. "Morphology of testes, spermatogenesis, sperm bundles, and spermatozoa ofKerria chinensis(Hemiptera: Kerriidae)". Canadian Entomologist 150, n. 5 (19 settembre 2018): 594–609. http://dx.doi.org/10.4039/tce.2018.39.

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AbstractThe filamentous spermatozoa of scale insects (Hemiptera) are highly modified compared with those of typical insects. Here, we investigate the morphology of the testes, sperm bundles, spermatozoa, and spermatogenesis of the winglessKerria chinensis(Mahdihassan) (Hemiptera: Kerriidae), a shellac-producing scale insect. Each testis contains two antiparallel groups of several hundred syncytial sperm bundles. In each spermatocyte cyst, 16 primary spermatocytes divide via inverted meiosis, resulting in 16 quadrinucleated spermatids, each having two euchromatic and two heterochromatic nuclei. During spermiogenesis, each spermatid produces two spermatozoa protruding out of the spermatid close to the two euchromatic nuclei and their tails then grow in opposite directions. In each cyst, the 32 spermatozoa form two sperm bundles lying in an antiparallel direction oriented to different ends of the testis. Each spermatozoon has three distinct regions, an apex, a filamentous region and a tail. The spermatozoa have long thread-like nuclear cores that occupy about one-fourth of the sperm body length, located primarily in the posterior half. At the anterior end of the spermatozoon is a translucent, swollen vesicle and a distal, densely-stained structure; a putative acrosome of a type not previously reported in the spermatozoa of scale insects.

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Wayman, C., S. Phillips, C. Lunny, T. Webb, L. Fawcett, R. Baxendale e G. Burgess. "Phosphodiesterase 11 (PDE11) regulation of spermatozoa physiology". International Journal of Impotence Research 17, n. 3 (31 marzo 2005): 216–23. http://dx.doi.org/10.1038/sj.ijir.3901307.

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6

Seftel, Allen D. "Phosphodiesterase 11 (PDE11) Regulation of Spermatozoa Physiology". Journal of Urology 174, n. 3 (settembre 2005): 1043–44. http://dx.doi.org/10.1016/s0022-5347(01)68504-5.

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7

Chaykin, S. "Non-fertilizing spermatozoa: Initiators of gestational physiology". Medical Hypotheses 23, n. 2 (giugno 1987): 153–55. http://dx.doi.org/10.1016/0306-9877(87)90151-4.

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8

Wang, Xiaona, Hua Qian, Xiaoyuan Huang, Jinjing Li, Jiayan Zhang, Nan Zhu, Hua Chen et al. "UCP2 Mitigates the Loss of Human Spermatozoa Motility by Promoting mROS Elimination". Cellular Physiology and Biochemistry 50, n. 3 (2018): 952–62. http://dx.doi.org/10.1159/000494479.

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Background/Aims: To demonstrate the function of uncoupling protein 2 (UCP2) in the regulation of human spermatozoa motility. Methods: Semen samples were collected from donors with either normal spermatozoa motility (normospermia [NS]) or poor spermatozoa motility (asthenospermia [AS]). UCP2 protein in spermatozoawas quantified by Western blotting. The level of mitochondrial reactive oxygen species (mROS) was evaluated by MitoSOX Red. The activity of mitochondrial membrane potential (MMP) in spermatozoa was evaluated by a JC-1 assay and the ATP level was monitored by a luciferin-luciferase assay. Results: UCP2 was expressed in both NS and AS groups, with the former exhibiting a higher level than the latter. Immunofluorescence analysis shows that UCP2 is mainly located at the mid-region of human spermatozoa. The inhibition of UCP2 by a highly selective inhibitor, Genipin, results in not only impaired spermatozoa mobility (P<.05) but also an elevated level of mROS (P<.05), suggesting that UCP2 is involved in the maintenance of the spermatozoa mobility, which probably is achieved by promoting mROS elimination. Furthermore, H2O2 treatment of spermatozoa increases the mROS level coupled with the loss of spermatozoa mobility. Unexpectedly, this treatment also has a positive impact on the expression of UCP2 within a certain range of supplemental H2O2, indicating the moderate mROS level possibly serves as a feedback signal to stimulate the expression of UCP2. Finally, the treatment of spermatozoa by an ROS scavenger, N-acetyl-l-cysteine (NAC),decreases the level of mROS and increases the curvilinear velocity (VCL) of spermatozoa, but the UCP2 level is not affected. Conclusion: These results suggest an UCP2–mROS–motility regulatory system exists for maintaining spermatozoa mobility in humans. In such a system, UCP2 fulfills its function by promoting mROS elimination, and slightly over-produced mROS in turn serves as a signal to stimulates the expression of UCP2. This regulatory system represents a new potential target for the discovery of novel pharmaceuticals for the treatment of patients with low spermatozoa motility.

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9

O’Flaherty, Cristian. "Peroxiredoxin 6: The Protector of Male Fertility". Antioxidants 7, n. 12 (24 novembre 2018): 173. http://dx.doi.org/10.3390/antiox7120173.

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The spermatozoon is a terminal cell with the unique purpose of delivering the paternal genome to the oocyte during fertilization. Once spermatozoa enter into the female reproductive tract, they count on only the antioxidant protection that they received during spermatogenesis and epididymal maturation. Peroxiredoxins (PRDXs), particularly PRDX6, are important players in the antioxidant protection and regulation of reactive oxygen species (ROS) levels in spermatozoa. PRDX6, through its peroxidase and calcium-independent phospholipase A2 activities, plays a major role in the regulation of ROS to maintain viability and motility and allow the spermatozoon to achieve fertilizing ability during the complex process of capacitation. The absence of PRDX6 is sufficient to promote abnormal reproductive outcomes in mice that resemble what we observe in infertile men. Indeed, Prdx6−/− spermatozoa display low motility and severe DNA damage, which is translated into reduced ability to fertilize oocytes in vitro or produce a low number of pups compared to wild-type controls. This review focuses on the role of PRDX6 as the primary antioxidant enzyme that protects the spermatozoon from oxidative-stress-associated damages to protect the paternal genome and assure fertility.

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10

Fernández-Alegre, Estela, Indira Álvarez-Fernández, Juan Carlos Domínguez, Adriana Casao e Felipe Martínez-Pastor. "Melatonin Non-Linearly Modulates Bull Spermatozoa Motility and Physiology in Capacitating and Non-Capacitating Conditions". International Journal of Molecular Sciences 21, n. 8 (13 aprile 2020): 2701. http://dx.doi.org/10.3390/ijms21082701.

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Bull spermatozoa physiology may be modulated by melatonin. We washed ejaculated spermatozoa free of melatonin and incubated them (4 h, 38 °C) with 0-pM, 1-pM, 100-pM, 10-nM and 1-µM melatonin in TALP-HEPES (non-capacitating) and TALP-HEPES-heparin (capacitating). This range of concentrations encompassed the effects mediated by melatonin receptors (pM), intracellular targets (nM–µM) or antioxidant activity (µM). Treatment effects were assessed as motility changes by computer-assisted sperm analysis (CASA) of motility and physiological changes by flow cytometry. Melatonin effects were more evident in capacitating conditions, with 100 pM reducing motility and velocity (VCL) while increasing a “slow” subpopulation. All concentrations decreased apoptotic spermatozoa and stimulated mitochondrial activity in viable spermatozoa, with 100 pM–1 µM increasing acrosomal damage, 10 nM–1 µM increasing intracellular calcium and 1 pM reducing the response to a calcium-ionophore challenge. In non-capacitating media, 1 µM increased hyperactivation-related variables and decreased apoptotic spermatozoa; 100 pM–1 µM increased membrane disorders (related to capacitation); all concentrations decreased mitochondrial ROS production. Melatonin concentrations had a modal effect on bull spermatozoa, suggesting a capacitation-modulating role and protective effect at physiological concentrations (pM). Some effects may be of practical use, considering artificial reproductive techniques.

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11

GRIVEAU, J. F., e D. LE LANNOU. "Reactive oxygen species and human spermatozoa: physiology and pathology". International Journal of Andrology 20, n. 2 (luglio 1997): 61–69. http://dx.doi.org/10.1046/j.1365-2605.1997.00044.x.

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12

Olabarrieta, Estibaliz, Lide Totorikaguena, Jon Romero-Aguirregomezcorta, Naiara Agirregoitia e Ekaitz Agirregoitia. "Mu opioid receptor expression and localisation in murine spermatozoa and its role in IVF". Reproduction, Fertility and Development 32, n. 4 (2020): 349. http://dx.doi.org/10.1071/rd19176.

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The endogenous opioid peptides are reported to be involved in the regulation of reproductive physiology. Many of the studies conclude with statements on the harmful effect of opioids on male fertility but, in fact, there are no studies regarding the real fertilisation potential of spermatozoa that have been exposed to opioids. The aim of the present study was to examine if modulation of mu opioid receptor (OPRM1) in murine spermatozoa during capacitation influenced embryo production after IVF. The presence of OPRM1 in murine mature spermatozoa was analysed by reverse transcription–polymerase chain reaction and immunofluorescence. We analysed the involvement of OPRM1 on IVF and pre-implantational embryo development by incubating the spermatozoa with the opioid agonist morphine and/or antagonist naloxone. We verified the presence of OPRM1 in murine mature spermatozoa, not only at the mRNA level but also the protein level. Moreover, incubation of the spermatozoa with morphine, before IVF, had an effect on the fertilisation rate of the spermatozoa and reduced the numbers of blastocysts, which was reversed by naloxone. Considering that opioids are widely used clinically, it is important to take into account their effect, via OPRM1, on the fertility of patients.

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13

Dangott, Lawrence J., e David L. Garbers. "Eggs Affect the Activity of Spermatozoa". Physiology 1, n. 4 (1 agosto 1986): 128–30. http://dx.doi.org/10.1152/physiologyonline.1986.1.4.128.

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It has been known for several decades that animal spermatozoa respond to substances associated with or produced by eggs and/or the female reproductive tract. Sperm motility and metabolism are affected, and, in addition, chemotaxis has been reported in various invertebrates and lower vertebrates. The mechanisms of communication begin to be understood, receptors on the sperm cell have been identified, and early biochemical events following receptor activation have been defined.

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14

Tushnova, M. P. "Spermotoxins and their role in the physiology and pathology of the body". Kazan medical journal 20, n. 2 (11 agosto 2021): 196–202. http://dx.doi.org/10.17816/kazmj76230.

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15

Cruz, Daniel Filipe, e Margarida Fardilha. "Relevance of peroxynitrite formation and 3-nitrotyrosine on spermatozoa physiology". Porto Biomedical Journal 1, n. 4 (settembre 2016): 129–35. http://dx.doi.org/10.1016/j.pbj.2016.07.004.

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16

Berby, Benoit, Cynthia Bichara, Aurélie Rives-Feraille, Fanny Jumeau, Pierre Di Pizio, Véronique Sétif, Louis Sibert, Ludovic Dumont, Chistine Rondanino e Nathalie Rives. "Oxidative Stress Is Associated with Telomere Interaction Impairment and Chromatin Condensation Defects in Spermatozoa of Infertile Males". Antioxidants 10, n. 4 (12 aprile 2021): 593. http://dx.doi.org/10.3390/antiox10040593.

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Telomere length can be influenced by reactive oxygen species (ROS) generated by lifestyle factors or environmental exposure. We sought to determine whether oxidative stress has an impact on sperm nuclear alterations, especially on chromatin organization and telomere interactions in the spermatozoa of infertile males. We performed an observational and prospective study including fifty-two males, allocated in the “case group” (30 infertile males presenting conventional semen parameter alterations) and the “control group” (22 males with normal conventional semen parameters). ROS detection was determined on spermatozoa using CellROX© probes. Sperm nuclear damage was assessed using quantitative fluorescence in situ hybridization (Q-FISH) for relative telomere length and telomere number, aniline blue staining for chromatin condensation, terminal deoxynucleotidyl transferase dUTP nick-end labeling for DNA fragmentation, and FISH for aneuploidy and 8-hydroxy-2′-deoxyguanosine immunostaining for oxidative DNA damages. Infertile males had significantly increased levels of cytoplasmic ROS and chromatin condensation defects as well as a higher mean number of telomere signals per spermatozoon in comparison with controls. In addition, the mean number of sperm telomere signals were positively correlated with the percentage of spermatozoa with chromatin condensation defect. In infertile males with conventional semen parameter alterations, oxidative stress is associated with telomere interaction impairment and chromatin condensation defects.

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Pinart, Elisabeth. "Ion Channels of Spermatozoa: Structure, Function, and Regulation Mechanisms". International Journal of Molecular Sciences 23, n. 11 (24 maggio 2022): 5880. http://dx.doi.org/10.3390/ijms23115880.

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Ion transport is essential for sperm physiology, being involved in sperm-cell differentiation and maturation, motility activation, chemotaxis towards the oocyte, and fertilization, as well as in sperm adaptation to the surrounding medium [...]

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Shen, Meng-Ru, Joel Linden, Shun-Sheng Chen e Sheng-Nan Wu. "IDENTIFICATION OF ADENOSINE RECEPTORS IN HUMAN SPERMATOZOA". Clinical and Experimental Pharmacology and Physiology 20, n. 7-8 (agosto 1993): 527–34. http://dx.doi.org/10.1111/j.1440-1681.1993.tb01736.x.

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Sullivan, Robert, e Fabrice Saez. "Epididymosomes, prostasomes, and liposomes: their roles in mammalian male reproductive physiology". REPRODUCTION 146, n. 1 (luglio 2013): R21—R35. http://dx.doi.org/10.1530/rep-13-0058.

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Mammalian spermatozoa are unique cells in many ways, and the acquisition of their main function, i.e. fertilization capacity, is a multistep process starting in the male gonad and ending near the female egg for the few cells reaching this point. Owing to the unique character of this cell, the molecular pathways necessary to achieve its maturation also show some specific characteristics. One of the most striking specificities of the spermatozoon is that its DNA is highly compacted after the replacement of histones by protamines, making the classical processes of transcription and translation impossible. The sperm cells are thus totally dependent on their extracellular environment for their protection against oxidative stress, for example, or for the molecular changes occurring during the transit of the epididymis; the first organ in which post-testicular maturation takes place. The molecular mechanisms underlying sperm maturation are still largely unknown, but it has been shown in the past three decades that extracellular vesicles secreted by the male reproductive tract are involved in this process. This review will examine the roles played by two types of naturally occurring extracellular vesicles, epididymosomes and prostasomes, secreted by the epididymis and the prostate respectively. We will also describe how the use of artificial vesicles, liposomes, contributed to the study of male reproductive physiology.

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Wallimann, Theo, Hanni Moser, Beat Zurbriggen, Gabi Wegmann e Hans M. Eppenberger. "Creatine kinase isoenzymes in spermatozoa". Journal of Muscle Research and Cell Motility 7, n. 1 (febbraio 1986): 25–34. http://dx.doi.org/10.1007/bf01756199.

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21

Zheng, X., M. Geiger, S. Ecke, E. Bielek, P. Donner, U. Eberspacher, W. D. Schleuning e B. R. Binder. "Inhibition of acrosin by protein C inhibitor and localization of protein C inhibitor to spermatozoa". American Journal of Physiology-Cell Physiology 267, n. 2 (1 agosto 1994): C466—C472. http://dx.doi.org/10.1152/ajpcell.1994.267.2.c466.

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Protein C inhibitor (PCI) is synthesized by cells throughout the male reproductive tract and is present in high concentrations (220 micrograms/ml) in seminal plasma. Seminal plasma as well as the acrosome of spermatozoa are rich in possible target proteases for PCI. We analyzed the interaction of PCI with acrosin, a serine protease stored in its zymogen form in the acrosome of spermatozoa. Purified human PCI inhibited the amidolytic activity of purified boar acrosin with an apparent second-order rate constant of 3.7 x 10(4) M-1.s-1. Inhibition was paralleled by the degradation of PCI from its 57- to its 54-kDa form. Human PCI also inhibited the amidolytic activity of activated human sperm extracts and formed complexes with acrosin as determined by an enzyme-linked immunosorbent assay. Immunocytochemistry revealed that morphologically abnormal spermatozoa stained for PCI antigen, whereas morphologically normal spermatozoa were negative. In immunoelectron microscopy, PCI was exclusively localized in the immediate vicinity of disrupted acrosomal membranes of sperm heads. These data suggest that PCI might function as a scavenger of prematurely activated acrosin, thereby protecting intact surrounding cells and seminal plasma proteins from possible proteolytic damage.

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KVIST, ULRIK, LARS BJÖRNDAHL, GODFRIED M. ROOMANS e CHRISTER LINDHOLMER. "Nuclear zinc in human epididymal and ejaculated spermatozoa". Acta Physiologica Scandinavica 125, n. 2 (ottobre 1985): 297–303. http://dx.doi.org/10.1111/j.1748-1716.1985.tb07719.x.

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23

Caballero, Julieta, Gilles Frenette e Robert Sullivan. "Post Testicular Sperm Maturational Changes in the Bull: Important Role of the Epididymosomes and Prostasomes". Veterinary Medicine International 2011 (2011): 1–13. http://dx.doi.org/10.4061/2011/757194.

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After spermatogenesis, testicular spermatozoa are not able to fertilize an oocyte, they must undergo sequential maturational processes. Part of these essential processes occurs during the transit of the spermatozoa through the male reproductive tract. Since the sperm become silent in terms of translation and transcription at the testicular level, all the maturational changes that take place on them are dependent on the interaction of spermatozoa with epididymal and accessory gland fluids. During the last decades, reproductive biotechnologies applied to bovine species have advanced significantly. The knowledge of the bull reproductive physiology is really important for the improvement of these techniques and the development of new ones. This paper focuses on the importance of the sperm interaction with the male reproductive fluids to acquire the fertilizing ability, with special attention to the role of the membranous vesicles present in those fluids and the recent mechanisms of protein acquisition during sperm maturation.

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Li, Yunlei, Yanyan Sun, Aixin Ni, Lei Shi, Panlin Wang, Adamu Mani Isa, Pingzhuang Ge et al. "Seminal Plasma Proteome as an Indicator of Sperm Dysfunction and Low Sperm Motility in Chickens". Molecular & Cellular Proteomics 19, n. 6 (20 aprile 2020): 1035–46. http://dx.doi.org/10.1074/mcp.ra120.002017.

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Molecular mechanisms underlying sperm motility have not been fully explained, particularly in chickens. The objective was to identify seminal plasma proteins associated with chicken sperm motility by comparing the seminal plasma proteomic profile of roosters with low sperm motility (LSM, n = 4) and high sperm motility (HSM, n = 4). Using a label-free MS-based method, a total of 522 seminal plasma proteins were identified, including 386 (∼74%) previously reported and 136 novel ones. A total of 70 differentially abundant proteins were defined, including 48 more-abundant, 15 less-abundant, and seven proteins unique to the LSM group (specific proteins). Key secretory proteins like less-abundant adhesion G-protein coupled receptor G2 (ADGRG2) and more-abundant serine peptidase inhibitor Kazal-type 2 (SPINK2) in the LSM suggested that the corresponding secretory tissues played a crucial role in maintaining sperm motility. Majority (80%) of the more-abundant and five specific proteins were annotated to the cytoplasmic domain which might be a result of higher plasma membrane damage and acrosome dysfunction in LSM. Additionally, more-abundant mitochondrial proteins were detected in LSM seminal plasma associated with lower spermatozoa mitochondrial membrane potential (ΔΨm) and ATP concentrations. Further studies showed that the spermatozoa might be suffering from oxidative stress, as the amount of spermatozoa reactive oxygen species (ROS) were largely enhanced, seminal malondialdehyde (MDA) concentrations were increased, and the seminal plasma total antioxidant capacity (T-AOC) were decreased. Our study provides an additional catalogue of chicken seminal plasma proteome and supports the idea that seminal plasma could be as an indicator of spermatozoa physiology. More-abundant of acrosome, mitochondria and sperm cytoskeleton proteins in the seminal plasma could be a marker of sperm dysfunction and loss of motility. The degeneration of spermatozoa caused by the reduced seminal T-AOC and enhanced oxidative stress might be potential determinants of low sperm motility. These results could extend our understanding of sperm motility and sperm physiology regulation.

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Nixon, Brett, Amanda L. Anderson, Elizabeth G. Bromfield, Jacinta H. Martin, Shenae L. Cafe, David A. Skerrett-Byrne, Matthew D. Dun, Andrew L. Eamens, Geoffry N. De Iuliis e Stephen D. Johnston. "Post-testicular sperm maturation in the saltwater crocodile Crocodylus porosus: assessing the temporal acquisition of sperm motility". Reproduction, Fertility and Development 33, n. 9 (2021): 530. http://dx.doi.org/10.1071/rd20204.

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Conservation efforts to secure the long-term survival of crocodilian species would benefit from the establishment of a frozen sperm bank in concert with artificial breeding technologies to maintain genetic diversity among captive assurance populations. Working towards this goal, our research has focused on the saltwater crocodile Crocodylus porosus as a tractable model for understanding crocodilian sperm physiology. In extending our systematic characterisation of saltwater crocodile spermatozoa, in this study we examined the development of motility during sperm transport through the excurrent duct system of the male crocodile. The results show that approximately 20% of crocodile testicular spermatozoa are immediately motile but experience a gradient of increasing motility (percentage motile and rate of movement) as they transit the male reproductive tract (epididymis). Moreover, we confirmed that, as in ejaculated crocodile spermatozoa, increased intracellular cAMP levels promoted a significant and sustained enhancement of sperm motility regardless of whether the cells were isolated from the testis or epididymis. Along with the development of artificial reproductive technologies, this research paves the way for the opportunistic recovery, storage and potential utilisation of post-mortem spermatozoa from genetically valuable animals.

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Omori, Toshihiro, e Takuji Ishikawa. "Swimming of Spermatozoa in a Maxwell Fluid". Micromachines 10, n. 2 (24 gennaio 2019): 78. http://dx.doi.org/10.3390/mi10020078.

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It has been suggested that the swimming mechanism used by spermatozoa could be adopted for self-propelled micro-robots in small environments and potentially applied to biomedical engineering. Mammalian sperm cells must swim through a viscoelastic mucus layer to find the egg cell. Thus, understanding how sperm cells swim through viscoelastic liquids is significant not only for physiology, but also for the design of micro-robots. In this paper, we developed a numerical model of a sperm cell in a linear Maxwell fluid based on the boundary element slender-body theory coupling method. The viscoelastic properties were characterized by the Deborah number (De), and we found that, under the prescribed waveform, the swimming speed decayed with the Deborah number in the small-De regime (De < 1.0). The swimming efficiency was independent of the Deborah number, and the decrease in the swimming speed was not significantly affected by the wave pattern.

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Peña, Fernando J., Cristian O’Flaherty, José M. Ortiz Rodríguez, Francisco E. Martín Cano, Gemma L. Gaitskell-Phillips, María C. Gil e Cristina Ortega Ferrusola. "Redox Regulation and Oxidative Stress: The Particular Case of the Stallion Spermatozoa". Antioxidants 8, n. 11 (19 novembre 2019): 567. http://dx.doi.org/10.3390/antiox8110567.

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Redox regulation and oxidative stress have become areas of major interest in spermatology. Alteration of redox homeostasis is recognized as a significant cause of male factor infertility and is behind the damage that spermatozoa experience after freezing and thawing or conservation in a liquid state. While for a long time, oxidative stress was just considered an overproduction of reactive oxygen species, nowadays it is considered as a consequence of redox deregulation. Many essential aspects of spermatozoa functionality are redox regulated, with reversible oxidation of thiols in cysteine residues of key proteins acting as an “on–off” switch controlling sperm function. However, if deregulation occurs, these residues may experience irreversible oxidation and oxidative stress, leading to malfunction and ultimately death of the spermatozoa. Stallion spermatozoa are “professional producers” of reactive oxygen species due to their intense mitochondrial activity, and thus sophisticated systems to control redox homeostasis are also characteristic of the spermatozoa in the horse. As a result, and combined with the fact that embryos can easily be collected in this species, horses are a good model for the study of redox biology in the spermatozoa and its impact on the embryo.

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Minelli, A., P. Miscetti, A. Proietti, L. Luzi e I. Mezzasoma. "Adenosine triphosphate catabolism in bovine spermatozoa". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology 110, n. 3 (marzo 1995): 605–11. http://dx.doi.org/10.1016/0305-0491(94)00180-3.

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Maxwell, W. M. C., e L. A. Johnson. "Physiology of spermatozoa at high dilution rates: the influence of seminal plasma". Theriogenology 52, n. 8 (dicembre 1999): 1353–62. http://dx.doi.org/10.1016/s0093-691x(99)00222-8.

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Ishijima, S., e H. Mohri. "A quantitative description of flagellar movement in golden hamster spermatozoa". Journal of Experimental Biology 114, n. 1 (1 gennaio 1985): 463–75. http://dx.doi.org/10.1242/jeb.114.1.463.

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Abstract (sommario):

Flagellar movement of golden hamster spermatozoa obtained from the testis and the caput and cauda epididymides was observed by a light microscope while holding them at their heads with a micropipette. Flagellar movement of capacitated spermatozoa and of reactivated spermatozoa demembranated with Triton X-100 was also observed. Testicular and caput epididymal spermatozoa showed weak movement in Tyrode's solution, whereas cauda epididymal spermatozoa showed vigorous movement. The flagellar bends of the cauda epididymal spermatozoa were almost planar. Capacitated spermatozoa moved with waves of a large amplitude. Demembranated spermatozoa reactivated with ATP only had a latent period before the initiation of flagellar movement, and beat at low frequency, whereas demembranated spermatozoa reactivated with both ATP and cAMP began to move immediately at high frequency. Thrust and hydrodynamic power output were calculated using the parameters for the typical waveforms of cauda epididymal spermatozoa before and after capacitation. The possible role of the large amplitude beat in capacitated spermatozoa is discussed. A comparison of the ‘principal’ and ‘reverse’ bends in golden hamster sperm flagella as defined by Woolley (1977) with those in sea urchin sperm flagella suggests that the so-called ‘principal’ bend in golden hamster sperm flagella corresponds to the reverse bend in sea urchin sperm flagella and vice versa.

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31

Miller, Jr, R. R., F. Beranek, A. L. Anderson, S. D. Johnston e B. Nixon. "Plasma and acrosomal membrane lipid content of saltwater crocodile spermatozoa". Reproduction, Fertility and Development 33, n. 9 (2021): 596. http://dx.doi.org/10.1071/rd21007.

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Abstract (sommario):

This study describes the chemical lipid composition of the sperm plasma and acrosomal membranes of the saltwater crocodile Crocodylus porosus with the aim of providing new insights into sperm physiology, particularly that associated with their preservation ex vivo. The specific fatty acid composition of the sperm plasma and acrosomal membranes is documented. The mean (±s.d.) ratio of unsaturated to saturated membrane fatty acids within the plasma membrane was 2.57±0.50, and was determined to be higher than a similar analysis of the lipids found in the acrosomal membrane (0.70±0.10). The saltwater crocodile sperm plasma membrane also contained remarkably high levels of cholesterol (mean (±s.d.) 40.7±4.5 nmol per 106 sperm cells) compared with the spermatozoa of other amniote species that have so far been documented. We suggest that this high cholesterol content could be conferring stability to the crocodile sperm membrane, allowing it to tolerate extreme osmotic fluxes and rapid changes in temperature. Our descriptive analysis now provides those interested in reptile and comparative sperm physiology an improved baseline database for interpreting biochemical changes associated with preservation pathology (e.g. cold shock and cryoinjury), epididymal sperm maturation and capacitation/acrosome reaction.

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32

Bintara, S. "Rasio Spermatozoa X:Y dan Kualitas Sperma pada Kambing Kacang dan Peranakan Ettawa". Sains Peternakan 9, n. 2 (6 febbraio 2017): 65. http://dx.doi.org/10.20961/sainspet.9.2.65-71.

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Abstract (sommario):

The objective of the study was to know the difference of X:Y spermatozoa ratio and sperm quality of Kacang and Ettawa-crossed breed goats. It was conducted at Laboratory of Animal Physiology and Reproduction, Faculty of Animal Science Universitas Gadjah Mada for three months, starting December 2009 to February 2010. Materials of the study were sperm collected from six two-year Ettawa-crossed breed goats weighing 31.5±2.2 kg and from six two-year Kacang goats weighing 18.0±2.1 kg. The sperm was collected using artificial vagina with frequency of twice a week for each goat and it was repeated eight times. The quality and quantity of the sperm was immediately evaluated by its volume, concentration, motility, viability and abnormality. To determine the ratio of X:Y spermatozoa, smear preparation was made and spermatozoa head was then measured using Scion Image software. The results of the measurement were used for identification of X or Y spermatozoa. Spermatozoa having bigger head than the average were identified as X and those having smaller head as Y. The result showed that the ratio of X:Y spermatozoa of Ettawa-crossed breed goats (50.6±1.8:49.4±1.8 %) was not significantly difference with that of Kacang goats (49.7±1,7:50.3±1.7 %). Sperm volume of Ettawa-crossed breed goats (1.00±0.2 ml) was higher than that of Kacang goats (0.62±0.2 ml). Sperm concentration of Ettawa-crossed breed goats (2,865±431 million/ml) was not significantly difference compared to that of Kacang goats (2,840±383 million/ml). Spermatozoa motility of Ettawa-crossed breed goats (66.7±9.8 %) was higher (P<0.05) than that of Kacang goats (50.0±7.1 %). Spermatozoa viability of Ettawa-crossed breed goats (80.0±7.1 %) was higher (P<0.05) than that of Kacang goats (67.5±9.4 %). Spermatozoa abnormality of Ettawa-crossed breed goats (8.2±3.3 %) was not significantly difference compared to that of Kacang goats (8.6±2.4 %). The study was concluded that the breeds of Ettawa-crossed breed and Kacang goats have indifferent ratio of X:Y spermatozoa, while the sperm volume, motility and viability of Ettawacrossed breed goats was better than that of Kacang goats.Key words: XY spermatozoa, quality and quantity, Ettawa-crossed breed, Kacang.

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33

Bintara, S. "Rasio Spermatozoa X:Y dan Kualitas Sperma pada Kambing Kacang dan Peranakan Ettawa". Sains Peternakan 9, n. 2 (6 febbraio 2017): 65. http://dx.doi.org/10.20961/sainspet.v9i2.4792.

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Abstract (sommario):

The objective of the study was to know the difference of X:Y spermatozoa ratio and sperm quality of Kacang and Ettawa-crossed breed goats. It was conducted at Laboratory of Animal Physiology and Reproduction, Faculty of Animal Science Universitas Gadjah Mada for three months, starting December 2009 to February 2010. Materials of the study were sperm collected from six two-year Ettawa-crossed breed goats weighing 31.5±2.2 kg and from six two-year Kacang goats weighing 18.0±2.1 kg. The sperm was collected using artificial vagina with frequency of twice a week for each goat and it was repeated eight times. The quality and quantity of the sperm was immediately evaluated by its volume, concentration, motility, viability and abnormality. To determine the ratio of X:Y spermatozoa, smear preparation was made and spermatozoa head was then measured using Scion Image software. The results of the measurement were used for identification of X or Y spermatozoa. Spermatozoa having bigger head than the average were identified as X and those having smaller head as Y. The result showed that the ratio of X:Y spermatozoa of Ettawa-crossed breed goats (50.6±1.8:49.4±1.8 %) was not significantly difference with that of Kacang goats (49.7±1,7:50.3±1.7 %). Sperm volume of Ettawa-crossed breed goats (1.00±0.2 ml) was higher than that of Kacang goats (0.62±0.2 ml). Sperm concentration of Ettawa-crossed breed goats (2,865±431 million/ml) was not significantly difference compared to that of Kacang goats (2,840±383 million/ml). Spermatozoa motility of Ettawa-crossed breed goats (66.7±9.8 %) was higher (P<0.05) than that of Kacang goats (50.0±7.1 %). Spermatozoa viability of Ettawa-crossed breed goats (80.0±7.1 %) was higher (P<0.05) than that of Kacang goats (67.5±9.4 %). Spermatozoa abnormality of Ettawa-crossed breed goats (8.2±3.3 %) was not significantly difference compared to that of Kacang goats (8.6±2.4 %). The study was concluded that the breeds of Ettawa-crossed breed and Kacang goats have indifferent ratio of X:Y spermatozoa, while the sperm volume, motility and viability of Ettawacrossed breed goats was better than that of Kacang goats.Key words: XY spermatozoa, quality and quantity, Ettawa-crossed breed, Kacang.

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34

Regnier, Glenn, Elke Bocksteins, Waleed F. Marei, Isabel Pintelon, Jean-Pierre Timmermans, Jo L. M. R. Leroy e Dirk J. Snyders. "Targeted deletion of the Kv6.4 subunit causes male sterility due to disturbed spermiogenesis". Reproduction, Fertility and Development 29, n. 8 (2017): 1567. http://dx.doi.org/10.1071/rd16075.

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Abstract (sommario):

Electrically silent voltage-gated potassium (KvS) channel subunits (i.e. Kv5–Kv6 and Kv8–Kv9) do not form functional homotetrameric Kv channels, but co-assemble with Kv2 subunits, generating functional heterotetrameric Kv2–KvS channel complexes in which the KvS subunits modulate the Kv2 channel properties. Several KvS subunits are expressed in testis tissue but knowledge about their contribution to testis physiology is lacking. Here, we report that the targeted deletion of Kv6.4 in a transgenic mouse model (Kcng4–/–) causes male sterility as offspring from homozygous females were only obtained after mating with wild-type (WT) or heterozygous males. Semen quality analysis revealed that the sterility of the homozygous males was caused by a severe reduction in total sperm-cell count and the absence of motile spermatozoa in the semen. Furthermore, spermatozoa of homozygous mice showed an abnormal morphology characterised by a smaller head and a shorter tail compared with WT spermatozoa. Comparison of WT and Kcng4–/– testicular tissue indicated that this inability to produce (normal) spermatozoa was due to disturbed spermiogenesis. These results suggest that Kv6.4 subunits are involved in the regulation of the late stages of spermatogenesis, which makes them a potentially interesting pharmacological target for the development of non-hormonal male contraceptives.

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35

Rotem, Ronit, Nadav Zamir, Nurit Keynan, Dalit Barkan, Haim Breitbart e Zvi Naor. "Atrial natriuretic peptide induces acrosomal exocytosis of human spermatozoa". American Journal of Physiology-Endocrinology and Metabolism 274, n. 2 (1 febbraio 1998): E218—E223. http://dx.doi.org/10.1152/ajpendo.1998.274.2.e218.

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Abstract (sommario):

Acrosomal exocytosis in mammalian spermatozoa is a process essential for fertilization. We report here that atrial natriuretic peptide (ANP) markedly stimulates acrosomal exocytosis of capacitated human spermatozoa. Typically, ANP exerts some of its actions via activation of the ANP receptor (ANPR-A), a particulate guanylyl cyclase-linked receptor, and subsequent formation of guanosine 3′,5′-cyclic monophosphate (cGMP). We found that ANP-stimulated acrosome reaction was inhibited by the competitive ANPR-A antagonist anantin, indicating a receptor-mediated process. A linear fragment of ANP, ANP-(13—28), and another ANP-like compound, brain natriuretic peptide, were inactive. The stimulatory effect of ANP on acrosome reaction was mimicked by the permeable cGMP analog, 8-bromo-cGMP (8-BrcGMP). Addition of the protein kinase C (PKC) inhibitors, staurosporine and GF-109203X, resulted in a dose-related inhibition of ANP-induced acrosome reaction. Also, downregulation of endogeneous PKC activity resulted in inhibition of ANP- but not 8-BrcGMP-induced acrosome reaction. Removal of extracellular Ca2+ abolished ANP-induced acrosome reaction. Thus ANP via Ca2+ influx, PKC activation, and stimulation of particulate guanylyl cyclase may play a role in the induction of acrosome reaction of human spermatozoa.

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36

De Angelis, A., S. Managò, M. A. Ferrara, M. Napolitano, G. Coppola e A. C. De Luca. "Combined Raman Spectroscopy and Digital Holographic Microscopy for Sperm Cell Quality Analysis". Journal of Spectroscopy 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/9876063.

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Abstract (sommario):

The diagnosis of male infertility is vastly complex. To date, morphology, motility, and concentration have been used as key parameters to establish the sperm normality and achieve pregnancy both in natural and in assisted fecundation. However, spermatozoa from infertile men could present a variety of alterations, such as DNA fragmentation, alterations of chromatin structure, and aneuploidy, which have been demonstrated to decrease reproductive capacity of men. Therefore, the ability to see detailed relationships between morphology and physiology in selected spermatozoa with submicrometric resolution in a nondestructive and noninvasive way and within a functional correlated context could be extremely important for the intracytoplasmic sperm injection procedure. In this review, we describe label-free optical spectroscopy and imaging techniques, based on the combination of Raman spectroscopy/imaging with holographic imaging, which are able to noninvasively measure the (bio)chemistry and morphology of sperm cells. We discuss the benefits and limitation of the proposed photonic techniques, with particular emphasis on applications in detection/characterization of sperm cell morphological defects and photodamage, and the identification/sorting of X- and Y-bearing bovine spermatozoa.

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37

Penfold, Linda M., Steven L. Monfort, Barbara A. Wolfe, Scott B. Citino e David E. Wildt. "Reproductive physiology and artificial insemination studies in wild and captive gerenuk (Litocranius walleri walleri)". Reproduction, Fertility and Development 17, n. 7 (2005): 707. http://dx.doi.org/10.1071/rd05077.

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Abstract (sommario):

Gerenuk antelope in North American zoos are descended from 28 founders imported from Kenya ~20 years ago. Intensive management is required to prevent inbreeding depression. Artificial insemination has potential for augmenting genetic management, but successful application requires a thorough understanding of species’ reproductive norms. Semen collected from captive (n = 10) and wild (n = 6) gerenuk contained low numbers of morphologically normal spermatozoa (~40%). Age, but not season, influenced (P < 0.05) the proportion of morphologically normal spermatozoa (mean ± s.e.m., 12–17 months of age, 10.3 ± 1.9%; 18–26 months of age, 34.4 ± 6.2%; 3–6 years of age, 40.0 ± 4.7%). Seasonality was investigated by analysing faecal testosterone and progesterone in males and females, respectively, by radioimmunoassays. Females cycled all year (ovarian cycle length, 18.7 ± 0.9 days). Testosterone in males did not vary (P > 0.05) with time of year. Three females (3/9, 33%) became pregnant by insemination with 9.75–54.0 × 106 motile fresh or frozen sperm after oestrus synchronisation with two prostaglandin F2α injections, 12 days apart. One female inseminated with frozen–thawed sperm delivered a full-term stillborn calf after 213 days gestation. These results characterise gerenuk reproductive norms and indicate that artificial insemination may be a useful tool in the genetic management of gerenuk.

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38

Matás, C., M. Sansegundo, S. Ruiz e J. Gadea. "135 THE EFFECT OF DIFFERENT TREATMENTS OF PORCINE EJACULATED AND EPIDIDYMAL SPERMATOZOA ON ROS GENERATION". Reproduction, Fertility and Development 18, n. 2 (2006): 176. http://dx.doi.org/10.1071/rdv18n2ab135.

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Abstract (sommario):

The production of pig embryos in vitro is still relatively inefficient compared with results obtained with oocytes matured and fertilized in vivo. The main reasons for this limited performance are polyspermy after IVF and the poor developmental ability of embryos produced by IVM-IVF (Kikuchi et al. 2002 Biol. Reprod. 1033-1041). Between factors affecting polyspermy are the sperm procedures before IVF. Usually, these procedures including centrifugations that increase reactive oxygen species (ROS) formation in spermatozoa. ROS play an important role in sperm physiology including capacitation. Physiological concentrations of ROS have been proposed to enhance sperm capacitation by increasing cAMP synthesis and by inhibiting protein tyrosine phosphatases whilst activating tyrosine kinases. In general, epididymal spermatozoa appear to be able to capacitate and fertilize eggs in vitro much more easily than ejaculated spermatozoa (Yanagimachi Mammalian Fertilization. In: The Physiology of Reproduction, Raven Press 1988; 135-182). In this study, we investigated how different sources (ejaculated spermatozoa vs. epididymal spermatozoa) and sperm capacitating methods, usually employed in porcine IVF, could be affect ROS generation. Sperm-rich fractions from five fertile boars and sperm from five different epididyimides were used. The semen samples were then: (i) washed in Dulbecco's phosphate-buffered saline (DPBS) supplemented with 0.1% BSA, (ii) left unwashed, or (iii) washed on a Percoll (Pharmacia, Uppsala, Sweden) gradient (Mat�s et al. 2003 Reproduction 125, 133-141). Production of ROS was measured by incubating the spermatozoa in the in vitro fertilization medium (TALP) in the presence of 0.7 �m 22,72-dichlorodihydrofluorescein diacetate at 37�C under 5% CO2 in 100% humidified air. Every 15 min (from 15 to 135) the samples were analyzed and evaluated by flow cytometry. Measurements were expressed as the mean green intensity fluorescence units and it was used as index of ROS generation (Gadea et al. 2005 J. Androl. 26, 396-404). ANOVA analysis revealed a significant effect of sperm treatment on the ROS generation (P < 0.001). The highest value was obtained in sperm washed on a Percoll gradient and the lowest in unwashed semen. When ejaculated vs. epididymal semen was analyzed, the same tendency was observed in both. However, the values were always lower in epididymal semen than in ejaculated semen (P < 0.001). As a conclusion, ROS generation is different between treatments and between semen procedures for the time interval studied, and this finding may help to explain the different outcome in IVF among laboratories. This work was supported by Ministerio de Educaci�n y Ciencia, AGL2003-03144.

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39

Ruiz-Díaz, Sara, Sergio Grande-Pérez, Sol Arce-López, Carolina Tamargo, Carlos Olegario Hidalgo e Serafín Pérez-Cerezales. "Changes in the Cellular Distribution of Tyrosine Phosphorylation and Its Relationship with the Acrosomal Exocytosis and Plasma Membrane Integrity during In Vitro Capacitation of Frozen/Thawed Bull Spermatozoa". International Journal of Molecular Sciences 21, n. 8 (15 aprile 2020): 2725. http://dx.doi.org/10.3390/ijms21082725.

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Abstract (sommario):

During sperm capacitation, intracellular signaling leads to protein tyrosine phosphorylation (PTP) of multiple cellular structures. However, the connection of this molecular signaling to the physiology of capacitated spermatozoa is not completely understood. This is the case of the short lifespan of capacitated spermatozoa and their increased susceptibility to initiate acrosomal exocytosis (AE) during incubation. Herein, by employing frozen/thawed bull spermatozoa, we aimed to study the relationship between PTP with AE and with plasma membrane integrity (PMI) at the cellular level. For this, we employed double staining following immunofluorescence for PTP combined with fluorescence probes for the acrosome (PNA-FITC) and PMI (LIVE/DEAD Fixable Dead Cell Stain Kit). Our results revealed that the presence of PTP at sperm head was less abundant in the sperm fraction that triggered the AE after 3 h of incubation under capacitating conditions, or by its induction with calcium ionophore, compared to the unreacted fraction. Furthermore, PTP at the equatorial region of the head (PTP-EQ) was enriched in the fraction showing damaged membrane while induction of AE with calcium ionophore did not alter the PMI and its relation to PTP-EQ. These results suggest that spontaneous AE and induced AE trigger similar cellular events regarding PTP and the spermatozoa showing PTP-EQ are more prone to suffer plasma membrane damage.

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40

Kim, Jong, e Sampath Parthasarathy. "Oxidation and the Spermatozoa". Seminars in Reproductive Medicine 16, n. 04 (dicembre 1998): 235–339. http://dx.doi.org/10.1055/s-2007-1016283.

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41

Ogbuewu, I. P., U. E. Ogundu, M. N. Opara, I. C. Okoli, D. O. Umesiobi, U. Herbert e M. U. Iloeje. "Spermatozoa Manipulation Techniques: A Current Assisted Reproductive Technology Tool Kit in Reproductive Physiology". Journal of Medical Sciences 10, n. 5 (15 agosto 2010): 110–23. http://dx.doi.org/10.3923/jms.2010.110.123.

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42

Luconi, Michaela, Lorella Bonaccorsi, Gianni Forti e Elisabetta Baldi. "Signal transduction mechanisms in human spermatozoa: from physiology to possible new therapeutic applications". Emerging Therapeutic Targets 4, n. 2 (aprile 2000): 239–53. http://dx.doi.org/10.1517/14728222.4.2.239.

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43

Chłopik, Angelika, e Anna Wysokińska. "Canine spermatozoa—What do we know about their morphology and physiology? An overview". Reproduction in Domestic Animals 55, n. 2 (14 dicembre 2019): 113–26. http://dx.doi.org/10.1111/rda.13596.

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44

Wang, Hua-Feng, Meng Chang, Ting-Ting Peng, Yi Yang, Na Li, Tao Luo, Yi-Min Cheng, Meng-Zhi Zhou, Xu-Hui Zeng e Li-Ping Zheng. "Exposure to Cadmium Impairs Sperm Functions by Reducing CatSper in Mice". Cellular Physiology and Biochemistry 42, n. 1 (2017): 44–54. http://dx.doi.org/10.1159/000477113.

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Abstract (sommario):

Background: Cadmium (Cd), a common environmental heavy metal and endocrine disruptor, is known to exert toxic effects on the testes. However, the mechanisms accounting for its toxicity in mature spermatozoa remain unclear. Methods: Adult male C57BL/6 mice were orally administered with CdCl2 for 5 weeks at 3 mg·kg-1·day-1. Additionally, mouse spermatozoa were incubated in vitro with different doses of CdCl2 (0, 10, 50, 250 µM). Several sperm functions including the sperm motility, viability and acrosome reaction (AR) ratio were then examined. Furthermore, the current and expression levels of both the sperm-specific Ca2+ channel (CatSper) and the sperm-specific K+ channel (KSper) were evaluated by patch-clamping and western blotting, respectively. Results: Our data showed that the motility, viability and AR of sperm exposed to cadmium significantly decreased in vivo and in vitro. Interestingly, these changes were correlated with changes in CatSper but not KSper. Conclusion: The findings indicate sperm dysfunction during both chronic and acute cadmium exposure as well as a specific role for CatSper in the reproductive toxicity of cadmium.

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45

Bumanlag, Edrian, Eleonora Scarlata e Cristian O’Flaherty. "Peroxiredoxin 6 Peroxidase and Ca2+-Independent Phospholipase A2 Activities Are Essential to Support Male-Mouse Fertility". Antioxidants 11, n. 2 (25 gennaio 2022): 226. http://dx.doi.org/10.3390/antiox11020226.

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Abstract (sommario):

Human infertility is an important health problem that affects one in six couples worldwide. Half of these cases are due to male infertility. Oxidative stress is a common culprit of male infertility, promoting lipid peroxidation and the oxidation of proteins and DNA in spermatozoa, thereby impairing motility, capacitation and fertilization. Peroxiredoxin 6 (PRDX6) possesses peroxidase and Ca2+-independent-phospholipase-A2 (iPLA2) activities that scavenge ROS and repair oxidized sperm membranes, respectively. PRDX6 protects spermatozoa against oxidative stress. Infertile men’s spermatozoa have impaired motility, elevated lipid peroxidation levels and DNA damage due to low PRDX6 levels. A lack of PRDX6 is associated with male-mouse infertility. Here, we determined the impact of the absence of PRDX6 peroxidase or iPLA2 activities on male-mouse fertility. Two-month-old male C57Bl6/J (wild-type), Prdx6−/−, C47S and D140A knock-in (peroxidase- and iPLA2-deficient, respectively) male mice were challenged with an in vivo oxidative stress triggered by tert-butyl hydroperoxide (t-BHP). C47S and D140A males produced smaller litters compared to wild-type controls. The t-BHP treatment promoted a lower number of pups, high levels of lipid peroxidation, tyrosine nitration, and DNA oxidation in all mutant spermatozoa compared to wild-type controls. All mutant spermatozoa had impaired capacitation and motility. In summary, both PRDX6 peroxidase and iPLA2 activities are essential to support male-mouse fertility.

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46

Wong, PY. "Abnormal fluid transport by the epididymis as a cause of obstructive azoospermia". Reproduction, Fertility and Development 2, n. 2 (1990): 115. http://dx.doi.org/10.1071/rd9900115.

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Abstract (sommario):

It has been known for more than a decade that in many mammalian species including man, spermatozoa once shed from the testis are immature, immotile and incapable of fertilizing the ovum. During their transit through the epididymis, they undergo various morphological and functional changes that confer on them the ability to ascend the female tract, to undergo an acrosome reaction, to penetrate the zona pellucida and to effect a successful fertilization. By the time spermatozoa have reached the cauda epididymidis, they are held in a quiescent state by factors in the epididymal fluid. The epididymis plays a vital role by creating a favourable fluid environment for sperm maturation and storage. The exact mechanisms underlying sperm maturation and storage are unclear and it appears that no single epididymal factor is held entirely responsible. In contrast, spermatozoa are directly bathed in the epididymal fluid; the fluidity of the microenvironmental has a direct effect on epididymal spermatozoa. The epididymal epithelium has been shown to transport electrolytes and water by processes involving ion pumps, ion carriers and ion channels. These components are under nervous, hormonal and paracrine control and are susceptible to interference by pharmacological agents. This paper reviews the physiology of electrolytes and fluid transport in the epididymis and describes how abnormal fluid transport across the epididymal duct could predispose towards epididymal obstruction, a condition that may occur in cystic fibrosis, Young's syndrome or other unexplained cases of male infertility.

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47

Zamir, N., D. Barkan, N. Keynan, Z. Naor e H. Breitbart. "Atrial natriuretic peptide induces acrosomal exocytosis in bovine spermatozoa". American Journal of Physiology-Endocrinology and Metabolism 269, n. 2 (1 agosto 1995): E216—E221. http://dx.doi.org/10.1152/ajpendo.1995.269.2.e216.

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Abstract (sommario):

The induction of acrosomal exocytosis in capacitated bull spermatozoa by atrial natriuretic peptide (ANP) was studied in vitro. ANP markedly stimulated acrosomal exocytosis in a calcium-dependent manner. Typically, ANP exerts its action via activation of the ANP receptor (ANPR-A), a particulate guanylyl cyclase-linked receptor, and subsequent formation of guanosine 3',5'-cyclic monophosphate (cGMP). We found that the ANP-induced acrosome reaction was inhibited by the competitive ANPR-A receptor antagonist-anantin, indicating a receptor-mediated effect. We could mimic the effect of ANP on the acrosome reaction by using 8-bromo-cGMP, suggesting that cGMP may serve as a signal transducer mediating the acrosome reaction. Indeed, the ANP-induced acrosome reaction was associated with elevation of cGMP levels. cGMP can also be formed by activation of the soluble form of guanylyl cyclase. Sodium nitroprusside (SNP) stimulated cGMP accumulation and acrosome reaction of capacitated spermatozoa. Thus ANP and the nitric oxide-releasing compound SNP, via activation of guanylyl cyclase (the former activating the particulate and the latter activating the soluble form of the enzyme), may play a significant role in the induction of the acrosome reaction.

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48

Aitken, Robert J., e Joel R. Drevet. "The Importance of Oxidative Stress in Determining the Functionality of Mammalian Spermatozoa: A Two-Edged Sword". Antioxidants 9, n. 2 (27 gennaio 2020): 111. http://dx.doi.org/10.3390/antiox9020111.

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Abstract (sommario):

This article addresses the importance of oxidative processes in both the generation of functional gametes and the aetiology of defective sperm function. Functionally, sperm capacitation is recognized as a redox-regulated process, wherein a low level of reactive oxygen species (ROS) generation is intimately involved in driving such events as the stimulation of tyrosine phosphorylation, the facilitation of cholesterol efflux and the promotion of cAMP generation. However, the continuous generation of ROS ultimately creates problems for spermatozoa because their unique physical architecture and unusual biochemical composition means that they are vulnerable to oxidative stress. As a consequence, they are heavily dependent on the antioxidant protection afforded by the fluids in the male and female reproductive tracts and, during the precarious process of insemination, seminal plasma. If this antioxidant protection should be compromised for any reason, then the spermatozoa experience pathological oxidative damage. In addition, situations may prevail that cause the spermatozoa to become exposed to high levels of ROS emanating either from other cells in the immediate vicinity (particularly neutrophils) or from the spermatozoa themselves. The environmental and lifestyle factors that promote ROS generation by the spermatozoa are reviewed in this article, as are the techniques that might be used in a diagnostic context to identify patients whose reproductive capacity is under oxidative threat. Understanding the strengths and weaknesses of ROS-monitoring methodologies is critical if we are to effectively identify those patients for whom treatment with antioxidants might be considered a rational management strategy.

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49

Morisawa, S., e M. Morisawa. "Acquisition of potential for sperm motility in rainbow trout and chum salmon". Journal of Experimental Biology 126, n. 1 (1 novembre 1986): 89–96. http://dx.doi.org/10.1242/jeb.126.1.89.

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Abstract (sommario):

The male reproductive organ of rainbow trout and chum salmon consists of a pair of testes and sperm ducts. Spermatozoa in the distal portion of the sperm ducts exhibit full motility in the K+-free medium. However, spermatozoa from the testis were almost immotile in this medium. This suggests that the spermatozoa acquire a capacity for movement during their passage from the testis along the sperm duct. In chum salmon migrating into a bay, the sperm duct was almost empty. However, after the fish have travelled upstream for 1 km to their spawning ground in the river, the spermatozoa have left the testis, moved into the sperm duct and are capable of becoming motile. Thus it is probable that the process of acquiring the ability to move occurs within a relatively short period in this simple reproductive organ. Additionally, testicular spermatozoa demembranated with Triton X-100 exhibited motility, although the motility was less than that of demembranated spermatozoa from the sperm duct, suggesting that the acquisition of motility may correspond with the development of some function of the plasma membrane.

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Morisawa, S., e M. Morisawa. "Induction of potential for sperm motility by bicarbonate and pH in rainbow trout and chum salmon". Journal of Experimental Biology 136, n. 1 (1 maggio 1988): 13–22. http://dx.doi.org/10.1242/jeb.136.1.13.

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Abstract (sommario):

Spermatozoa of rainbow trout and chum salmon, which have no potential for motility in the testis, acquire that potential in the sperm duct. This paper demonstrates that there is little difference between the levels of sodium, potassium, calcium, magnesium, chloride and osmolality of the seminal plasma in the testis and in the sperm duct. However, the bicarbonate concentration of the seminal plasma and the pH value of semen were higher in the sperm duct than in the testis. When immotile spermatozoa obtained from the testis were incubated in artificial seminal plasma with a high pH and containing HCO3-, spermatozoa became motile within 1 h. These results suggest that spermatozoa of salmonid fish acquire the potential for motility as a result of the increase in seminal bicarbonate concentration and pH that occurs as spermatozoa pass from the testis to the sperm duct.

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