scholarly journals Ca2+-stores in sperm: their identities and functions

Reproduction ◽  
2009 ◽  
Vol 138 (3) ◽  
pp. 425-437 ◽  
Author(s):  
Sarah Costello ◽  
Francesco Michelangeli ◽  
Katherine Nash ◽  
Linda Lefievre ◽  
Jennifer Morris ◽  
...  
Keyword(s):  
Acrosome Reaction ◽  
Somatic Cells ◽  
Functional Interaction ◽  
Mammalian Sperm ◽  
Intracellular Ca ◽  
Principal Piece ◽  
Oscillations And Waves ◽  
Molecular Components ◽  
Cellular Ca ◽  
Discrete Functions

Intracellular Ca2+stores play a central role in the regulation of cellular [Ca2+]iand the generation of complex [Ca2+] signals such as oscillations and waves. Ca2+signalling is of particular significance in sperm cells, where it is a central regulator in many key activities (including capacitation, hyperactivation, chemotaxis and acrosome reaction) yet mature sperm lack endoplasmic reticulum and several other organelles that serve as Ca2+stores in somatic cells. Here, we review i) the evidence for the expression in sperm of the molecular components (pumps and channels) which are functionally significant in the activity of Ca2+stores of somatic cells and ii) the evidence for the existence of functional Ca2+stores in sperm. This evidence supports the existence of at least two storage organelles in mammalian sperm, one in the acrosomal region and another in the region of the sperm neck and midpiece. We then go on to discuss the probable identity of these organelles and their discrete functions: regulation by the acrosome of its own secretion and regulation by membranous organelles at the sperm neck (and possibly by the mitochondria) of flagellar activity and hyperactivation. Finally, we consider the ability of the sperm discretely to control mobilisation of these stores and the functional interaction of stored Ca2+at the sperm neck/midpiece with CatSper channels in the principal piece in regulation of the activities of mammalian sperm.

scholarly journals A caged progesterone analog alters intracellular Ca2+ and flagellar bending in human sperm

Reproduction ◽  
2012 ◽  
Vol 144 (1) ◽  
pp. 101-109 ◽  
Author(s):  
M Rocio Servin-Vences ◽  
Yoshiro Tatsu ◽  
Hisanori Ando ◽  
Adán Guerrero ◽  
Noboru Yumoto ◽  
...  
Keyword(s):  
Time Lag ◽  
Human Sperm ◽  
Human Spermatozoa ◽  
Mammalian Sperm ◽  
Intracellular Ca ◽  
Stroboscopic Illumination ◽  
Initial Action ◽  
Principal Piece ◽  
Short Time ◽  
First Time

Progesterone is a physiological agonist for mammalian sperm, modulating its flagellar movement and facilitating the acrosome reaction. To study the initial action of progesterone, we developed a caged analog with a photosensitive group: nitrophenylethanediol, at position 20. Using this compound combined with stroboscopic illumination, we performed Ca2+imaging of human spermatozoa and analyzed the effects of progesterone on the intracellular Ca2+concentration ([Ca2+]i) of beating flagella for the first time. We observed a transient [Ca2+]iincrease in the head and the flagellum upon photolysis of the caged progesterone and an increase in flagellar curvature. Detailed kinetic analysis revealed that progesterone elicits an increase in the [Ca2+]iimmediately in the flagellum (mid-piece and principal piece), thereafter in the head with a short time lag. This observation is different from the progesterone-induced Ca2+mobilization in mouse spermatozoa, where the Ca2+rise initiates at the base of the sperm head. Our finding is mostly consistent with the recent discovery that progesterone activates CatSper channels in human spermatozoa, but not in mouse spermatozoa.

scholarly journals Localization of sperm intracellular Ca2+ keeps fertilizability in the newt vas deferens

Reproduction ◽  
2020 ◽  
Vol 159 (3) ◽  
pp. 339-349
Author(s):  
Nanae Makino ◽  
Nozomi Sato ◽  
Eriko Takayama-Watanabe ◽  
Akihiko Watanabe
Keyword(s):  
Sperm Motility ◽  
Salt Solution ◽  
Acrosome Reaction ◽  
Vas Deferens ◽  
Sperm Quality ◽  
Ethylene Glycol Tetraacetic Acid ◽  
Channel Blockers ◽  
Tetraacetic Acid ◽  
Intracellular Ca ◽  
Principal Piece

Sperm intracellular Ca2+ is crucial for the induction of sperm-egg interaction, but little is known about the significance of Ca2+ maintenance prior to induction. In sperm of the newt Cynops pyrrhogaster, intracellular Ca2+ is localized to the midpiece during storage in the vas deferens, while extracellular Ca2+ is influxed in modified Steinberg’s salt solution to promote a spontaneous acrosome reaction related to the decline of sperm quality. In the present study, sperm from the vas deferens were loaded with the Ca2+ indicator Fluo8H, and changes in Ca2+ localization in modified Steinberg’s salt solution were examined. Calcium ions expanded from the cytoplasmic area of the midpiece to the entire tail in most sperm during a 1-h incubation and localized to the principal piece in some sperm within 24 h. Similar changes in Ca2+ localization were observed in reconstructed vas deferens solution that included ions and pH at equivalent levels to those in the vas deferens fluid. Sperm with Ca2+ localization in the entire tail or the principal piece weakened or lost responsiveness to sperm motility-initiating substances, which trigger sperm motility for fertilization, but responded to a trigger for acrosome reaction. The change in Ca2+ localization was delayed and transiently reversed by ethylene glycol tetraacetic acid or a mixture of Ca2+ channel blockers including Ni2+ and diltiazem. These results suggest that C. pyrrhogaster sperm localize intracellular Ca2+ to the midpiece through Ca2+ transport in the vas deferens to allow for responses to sperm motility-initiating substances.

scholarly journals Identification and spatial distribution of glycine receptor subunits in human sperm

Reproduction ◽  
2008 ◽  
Vol 136 (4) ◽  
pp. 387-390 ◽  
Author(s):  
Priyadarsini Kumar ◽  
Stanley Meizel
Keyword(s):  
Spatial Distribution ◽  
Western Blot ◽  
Blot Analysis ◽  
Acrosome Reaction ◽  
Glycine Receptor ◽  
Human Sperm ◽  
Equatorial Region ◽  
Mammalian Sperm ◽  
Principal Piece ◽  
Sperm Acrosome Reaction

The human sperm surface glycine receptor (GLR) plays a role in an important fertilization event, the sperm acrosome reaction. Here, by western blot analysis, we report the presence of GLRA1, GLRA2, GLRA3, and GLRB subunits in human sperm. Immunolocalization studies showed that the GLRA1 and GLRA2 subunits are present in the equatorial region, the GLRA3 subunit in the flagellar principal piece, and the GLRB subunit in the acrosomal region of sperm. This first demonstration of isoforms of the sperm GLRA subunit and of a differential spatial distribution of the α and β subunits on the surface of mammalian sperm suggests the possibility that human sperm GLRs have more than one function.

scholarly journals Molecular physiology and pathology of Ca2+-conducting channels in the plasma membrane of mammalian sperm

Reproduction ◽  
2005 ◽  
Vol 129 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Ricardo Felix
Keyword(s):  
Plasma Membrane ◽  
Acrosome Reaction ◽  
Current Evidence ◽  
Molecular Physiology ◽  
Mammalian Sperm ◽  
Fertilizing Ability ◽  
Intracellular Ca ◽  
Gene Defects ◽  
Sperm Fertilizing Ability ◽  
Sperm Functions

Current evidence indicates that mechanisms controlling the intracellular Ca2+concentration play pivotal roles in determining sperm fertilizing ability. Multiple Ca2+-permeable channels have been identified and characterized in the plasma membrane and in the acrosome membrane of mammalian sperm. This review summarizes the recent findings and assesses the evidence suggesting that these channels play roles in controlling a host of sperm functions ranging from motility to the acrosome reaction, and describes recent advances in the identification of the underlying gene defects of inherited sperm Ca2+channelopathies.

Cryopreservation alters the Ca2+ flux of bovine spermatozoa

1994 ◽  
Vol 74 (1) ◽  
pp. 45-51 ◽  
Author(s):  
J. L. Bailey ◽  
M. M. Buhr
Keyword(s):  
Key Words ◽  
Acrosome Reaction ◽  
Intracellular Ca ◽  
Bovine Spermatozoa ◽  
Free Media ◽  
Cellular Ca ◽  
Over Time

Capacitation and the acrosome reaction are Ca2+-dependent events that must be properly timed for successful fertilization to occur. To test the hypothesis that the cryopreservation procedures alter the ability of bovine spermatozoa to regulate Ca2+, the ability of Percoll-washed fresh and cryopreserved spermatozoa obtained from the same ejaculate (four ejaculates from each of six bulls) to regulate Ca2+ over time was monitored using the fluorescent Ca2+ chelator indo-1. The ability of spermatozoa to control Ca2+ levels varied among ejaculates from a bull, and among bulls; these effects were statistically accounted for in the analysis of the effects of cryopreservation. Initially, cryopreserved spermatozoa had lower viability, motility, and normal acrosome scores and more intra- and extra-cellular Ca2+ than fresh spermatozoa. Intra- and extra-cellular Ca2+ was monitored for 150 min, with 1 mM exogenous Ca2+ or buffer being added at 30 min to the spermatozoa being used to monitor intracellular Ca2+. By 30 min, extracellular Ca2+ was higher for fresh cells and then remained constant. Intracellular Ca2+ of fresh and cryopreserved spermatozoa in Ca2+-free media slowly increased. While both fresh and cryopreserved cells in Ca2+-supplemented media accumulated Ca2+ more rapidly, cryopreserved spermatozoa did so faster than fresh. Post-experimental viability was lower in cryopreserved spermatozoa that had been exposed to exogenous Ca2+. In conclusion, cryopreservation affects initial intra- and extra-cellular Ca2+ levels of bovine spermatozoa, and their ability to control subsequent rates of Ca2+ accumulation. Key words: Bovine, cryopreservation, calcium, indo–1, spermatozoa

scholarly journals Asterosap, an Egg Jelly Peptide, Elevate Intracellular Ca2+ and Activate the Motility of Spermatozoa

2013 ◽  
Vol 19 (1) ◽  
pp. 79-88 ◽  
Author(s):  
MS Islam ◽  
T Akhter ◽  
M Matsumoto
Keyword(s):  
Plasma Membrane ◽  
Cyclic Gmp ◽  
Guanylyl Cyclase ◽  
Acrosome Reaction ◽  
Nickel Chloride ◽  
Selective Inhibitor ◽  
Ion Flux ◽  
Intracellular Ca ◽  
A Cell ◽  
Egg Jelly

Components from the outer envelopes of the egg that influence the flagellar beating and acrosome reaction of spermatozoa are regulated by ion flux across the plasma membrane. Asterosap, a sperm-activating peptide from the starfish egg jelly layer, causes a transient increase in intracellular cyclic GMP (cGMP) through the activation of the asterosap receptor, a guanylyl cyclase (GC), and causes an increase in intracellular Ca2+. Here we describe the pathway of asterosap-induced Ca2+ elevation using different Ca2+ channel antagonists. Fluo-4 AM, a cell permeable Ca2+ sensitive dye was used to determine the channel caused by the asterosap-induced Ca2+ elevation in spermatozoa. Different L-type Ca2+ channel antagonists, a non specific Ca2+ channel antagonist (nickel chloride), and a store-operated Ca2+ channel (SOC) antagonist do not show any significant response on asterosap-induced Ca2+ elevation, whereas KB-R7943, a selective inhibitor against Na+/Ca2+ exchanger (NCX) inhibited effectively. We also analyzed the flagellar movement of spermatozoa in artificial seawater (ASW) containing the asterosap at 100 nM ml?1. We found that spermatozoa swam vigorously with more symmetrical flagellar movement in asterosap than in ASW and KB-R7943 significantly inhibited the flagellar movement.DOI: http://dx.doi.org/10.3329/pa.v19i1.17358 Progress. Agric. 19(1): 79 - 88, 2008 

scholarly journals Discrete Dynamic Model of the Mammalian Sperm Acrosome Reaction: The Influence of Acrosomal pH and Physiological Heterogeneity

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrés Aldana ◽  
Jorge Carneiro ◽  
Gustavo Martínez-Mekler ◽  
Alberto Darszon
Keyword(s):  
Acrosome Reaction ◽  
Human Sperm ◽  
Extracellular Medium ◽  
Mammalian Sperm ◽  
Discrete Dynamic Model ◽  
Acrosomal Exocytosis ◽  
Mammalian Fertilization ◽  
Main Components ◽  
Discrete Mathematical Model ◽  
Physiological Heterogeneity

The acrosome reaction (AR) is an exocytotic process essential for mammalian fertilization. It involves diverse physiological changes (biochemical, biophysical, and morphological) that culminate in the release of the acrosomal content to the extracellular medium as well as a reorganization of the plasma membrane (PM) that allows sperm to interact and fuse with the egg. In spite of many efforts, there are still important pending questions regarding the molecular mechanism regulating the AR. Particularly, the contribution of acrosomal alkalinization to AR triggering physiological conditions is not well understood. Also, the dependence of the proportion of sperm capable of undergoing AR on the physiological heterogeneity within a sperm population has not been studied. Here, we present a discrete mathematical model for the human sperm AR based on the physiological interactions among some of the main components of this complex exocytotic process. We show that this model can qualitatively reproduce diverse experimental results, and that it can be used to analyze how acrosomal pH (pHa) and cell heterogeneity regulate AR. Our results confirm that a pHa increase can on its own trigger AR in a subpopulation of sperm, and furthermore, it indicates that this is a necessary step to trigger acrosomal exocytosis through progesterone, a known natural inducer of AR. Most importantly, we show that the proportion of sperm undergoing AR is directly related to the detailed structure of the population physiological heterogeneity.

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