101
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Insect stage-specific receptor adenylate cyclases are localized to distinct subdomains of the Trypanosoma brucei Flagellar membrane. EUKARYOTIC CELL 2014; 13:1064-76. [PMID: 24879126 DOI: 10.1128/ec.00019-14] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Increasing evidence indicates that the Trypanosoma brucei flagellum (synonymous with cilium) plays important roles in host-parasite interactions. Several studies have identified virulence factors and signaling proteins in the flagellar membrane of bloodstream-stage T. brucei, but less is known about flagellar membrane proteins in procyclic, insect-stage parasites. Here we report on the identification of several receptor-type flagellar adenylate cyclases (ACs) that are specifically upregulated in procyclic T. brucei parasites. Identification of insect stage-specific ACs is novel, as previously studied ACs were constitutively expressed or confined to bloodstream-stage parasites. We show that procyclic stage-specific ACs are glycosylated, surface-exposed proteins that dimerize and possess catalytic activity. We used gene-specific tags to examine the distribution of individual AC isoforms. All ACs examined localized to the flagellum. Notably, however, while some ACs were distributed along the length of the flagellum, others specifically localized to the flagellum tip. These are the first transmembrane domain proteins to be localized specifically at the flagellum tip in T. brucei, emphasizing that the flagellum membrane is organized into specific subdomains. Deletion analysis reveals that C-terminal sequences are critical for targeting ACs to the flagellum, and sequence comparisons suggest that differential subflagellar localization might be specified by isoform-specific C termini. Our combined results suggest insect stage-specific roles for a subset of flagellar adenylate cyclases and support a microdomain model for flagellar cyclic AMP (cAMP) signaling in T. brucei. In this model, cAMP production is compartmentalized through differential localization of individual ACs, thereby allowing diverse cellular responses to be controlled by a common signaling molecule.
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102
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Kantsler V, Dunkel J, Blayney M, Goldstein RE. Rheotaxis facilitates upstream navigation of mammalian sperm cells. eLife 2014; 3:e02403. [PMID: 24867640 PMCID: PMC4031982 DOI: 10.7554/elife.02403] [Citation(s) in RCA: 134] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
A major puzzle in biology is how mammalian sperm maintain the correct swimming direction during various phases of the sexual reproduction process. Whilst chemotaxis may dominate near the ovum, it is unclear which cues guide spermatozoa on their long journey towards the egg. Hypothesized mechanisms range from peristaltic pumping to temperature sensing and response to fluid flow variations (rheotaxis), but little is known quantitatively about them. We report the first quantitative study of mammalian sperm rheotaxis, using microfluidic devices to investigate systematically swimming of human and bull sperm over a range of physiologically relevant shear rates and viscosities. Our measurements show that the interplay of fluid shear, steric surface-interactions, and chirality of the flagellar beat leads to stable upstream spiralling motion of sperm cells, thus providing a generic and robust rectification mechanism to support mammalian fertilisation. A minimal mathematical model is presented that accounts quantitatively for the experimental observations. DOI:http://dx.doi.org/10.7554/eLife.02403.001 A sperm cell must complete a long and taxing journey to stand a chance of fertilising an egg cell. This quest covers a distance that is thousands of times longer than the length of a sperm cell. It also passes through the diverse environments of the cervix, the uterus and, finally, the oviduct, where there might be an egg to fertilise. How the sperm cells manage to stay on course over this distance is a mystery, although it has been suggested that many different factors, including chemical signals and fluid flow, are involved. The fluids that the sperm cells travel through are not static. Evidence suggests that contractions of the cervix and uterus help to pump sperm cells along the first part of their journey. However, mucus flows out of the oviduct in the opposite direction to way the sperm cells need to go. Sperm cells mostly move along the walls of the cervix, uterus, and oviduct. This means that sperm cells must contend with two properties of the fluids they travel through—the viscosity (or ‘thickness’) of the fluid, and the fact that different parts of the fluid will flow at different speeds, depending on how close it is to the wall (‘shear flow’). Kantsler et al. have now used a technique called microfluidics—which involves forcing tiny amounts of liquid to flow through very narrow channels—to study how the movement of human and bull sperm cells along a surface is affected by the viscosity and flow rate of the fluid they are swimming through. The sperm cells were found to swim upstream, moving along the walls of the channels in a spiral movement. This is likely to help the sperm cells to find the egg, because spiralling around the oviduct will increase the chances of meeting the egg. Kantsler et al. also built a mathematical model that describes how the sperm cells move. Although further work is needed to better understand the role played by chemical signals, understanding how fluid flow and viscosity influence sperm cells could lead to more effective artificial insemination techniques. DOI:http://dx.doi.org/10.7554/eLife.02403.002
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Affiliation(s)
- Vasily Kantsler
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jörn Dunkel
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | | | - Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
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103
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Sugiyama H, Chandler DE. Sperm guidance to the egg finds calcium at the helm. PROTOPLASMA 2014; 251:461-475. [PMID: 24085342 DOI: 10.1007/s00709-013-0550-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 09/05/2013] [Indexed: 06/02/2023]
Abstract
Sperm respond to multiple cues during guidance to the egg including chemical attractants, temperature, and fluid flow. Of these, sperm chemotaxis has been studied most extensively-over 100 years-but only recently has it started to be understood at the molecular level. The long gestation in this understanding has largely been due to technical limitations that include the detection of calcium signal dynamics in a relatively small structure-the flagellum, measurement of actual chemoattractant gradients, the fact that only subpopulations of sperm respond at any given time, and the diversity in swimming behaviors that sperm exhibit from different species. Today, measurements of flagellar calcium signals on a fast time scale, discovery of the ion channels and organelles that may regulate these signals, and better understanding and quantitation of sperm swimming behaviors involved have given more certainty to our understanding of sperm directional swimming and its control by characteristic, calcium-directed asymmetric flagellar bends. Future research will need to apply these technical advances to other forms of sperm guidance such as thermotaxis and rheotaxis as well as gaining an understanding of how the flagellar apparatus is controlled by calcium.
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Affiliation(s)
- Hitoshi Sugiyama
- Science and Technology Group, Okinawa Institute of Science and Technology, Okinawa, 904-0495, Japan
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104
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Tung CK, Ardon F, Fiore A, Suarez SS, Wu M. Cooperative roles of biological flow and surface topography in guiding sperm migration revealed by a microfluidic model. LAB ON A CHIP 2014; 14:1348-56. [PMID: 24535032 PMCID: PMC4497544 DOI: 10.1039/c3lc51297e] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Successful reproduction in mammals requires sperm to swim against a fluid flow and through the long and complex female reproductive tract before reaching the egg in the oviduct. Millions of them do not make it. Despite their clinical importance, the roles played in sperm migration by the diverse biophysical and biochemical microenvironments within the reproductive tract are largely unknown. In this article, we present the development of a double layer microfluidic device that recreates two important biophysical environments within the female reproductive tract: fluid flow and surface topography. The unique feature of the device is that it enables one to study the cooperative roles of fluid flow and surface topography in guiding sperm migration. Using bull sperm as a model system, we found that microfluidic grooves embedded on a channel surface facilitate sperm migration against fluid flow. These findings suggest ways to design in vitro fertilization devices to treat infertility and to develop non-invasive contraceptives that use a microarchitectural design to entrap sperm.
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Affiliation(s)
- Chih-kuan Tung
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Florencia Ardon
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA
| | - Alyssa Fiore
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
| | - Susan S. Suarez
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA
| | - Mingming Wu
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA
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105
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Brenker C, Zhou Y, Müller A, Echeverry FA, Trötschel C, Poetsch A, Xia XM, Bönigk W, Lingle CJ, Kaupp UB, Strünker T. The Ca2+-activated K+ current of human sperm is mediated by Slo3. eLife 2014; 3:e01438. [PMID: 24670955 PMCID: PMC3966514 DOI: 10.7554/elife.01438] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sperm are equipped with a unique set of ion channels that orchestrate fertilization. In mouse sperm, the principal K+ current (IKSper) is carried by the Slo3 channel, which sets the membrane potential (Vm) in a strongly pHi-dependent manner. Here, we show that IKSper in human sperm is activated weakly by pHi and more strongly by Ca2+. Correspondingly, Vm is strongly regulated by Ca2+ and less so by pHi. We find that inhibitors of Slo3 suppress human IKSper, and we identify the Slo3 protein in the flagellum of human sperm. Moreover, heterologously expressed human Slo3, but not mouse Slo3, is activated by Ca2+ rather than by alkaline pHi; current–voltage relations of human Slo3 and human IKSper are similar. We conclude that Slo3 represents the principal K+ channel in human sperm that carries the Ca2+-activated IKSper current. We propose that, in human sperm, the progesterone-evoked Ca2+ influx carried by voltage-gated CatSper channels is limited by Ca2+-controlled hyperpolarization via Slo3. DOI:http://dx.doi.org/10.7554/eLife.01438.001 A sperm that has been ejaculated into the female reproductive tract must complete a number of tasks to pass on its genes to the next generation. First it must travel along a meandering route to encounter an egg, before pushing through a jelly-like coating that surrounds the egg and then, finally, fusing with the egg’s surface membrane. In order to complete these steps and fertilise the egg, a sperm must undergo a process called ‘capacitation’. This process, and a variety of other sperm functions, involves the controlled flux of positive ions into and out of the sperm via specific ion channels that are located in the cell membrane. The properties of the ion channels that allow protons and calcium ions to move into and out of human sperm are well understood, but less is known about the channels that control the movement of potassium ions. In mice, a channel called Slo3 allows potassium ions to flow out of the sperm and makes the membrane voltage of these cells more negative. Also, in mice, this channel is essential for the sperm to function correctly, and for fertilization. However, in humans, it is unclear if the Slo3 channel is present in sperm and if it performs the same role. Now, Brenker et al. have shown that the flow of potassium ions out of human sperm occurs via the Slo3 channel, and that human Slo3 is responsible for setting the membrane voltage of these cells. However, whereas the mouse Slo3 channel is opened in response to a decrease in the concentration of protons within the sperm (i.e., an increase of the pH inside the cell), human Slo3 is largely controlled by changes in the levels of calcium ions. An increase in the calcium concentration within the cell opens the human Slo3 channel, more than a decrease in the proton concentration does. Altogether, Brenker et al. identify Slo3 as the principal potassium channel in human sperm and reveal more fundamental differences between human sperm and mouse sperm. Thereby, this work further stresses the need to be cautious about using mice as a model of male fertility in humans. DOI:http://dx.doi.org/10.7554/eLife.01438.002
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Affiliation(s)
- Christoph Brenker
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, Bonn, Germany
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106
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T-type Ca2+ channels in spermatogenic cells and sperm. Pflugers Arch 2014; 466:819-31. [DOI: 10.1007/s00424-014-1478-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 02/08/2014] [Indexed: 12/14/2022]
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107
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Taste Receptor Gene Expression Outside the Gustatory System. TOPICS IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1007/7355_2014_79] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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108
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Alvarez L, Friedrich BM, Gompper G, Kaupp UB. The computational sperm cell. Trends Cell Biol 2013; 24:198-207. [PMID: 24342435 DOI: 10.1016/j.tcb.2013.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Revised: 10/13/2013] [Accepted: 10/14/2013] [Indexed: 10/25/2022]
Abstract
Sperm are guided to the egg by a gradient of chemical attractants - a process called chemotaxis. The binding of the chemoattractant to receptors on the surface of the flagellum triggers a cascade of signaling events that eventually lead to an influx of Ca(2+) ions. Based on these Ca(2+) surges, which control the waveform of the flagellar beat, sperm adjust their swimming path toward the egg. In past years, many components of chemotactic signaling have been identified. Moreover, kinetic spectroscopy and imaging techniques unraveled the sequence of cellular events controlling swimming behavior. During navigation in a chemical gradient, sperm perform a surprising variety of computational operations. Here we discuss theoretical concepts of navigation strategies and the cellular underpinnings.
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Affiliation(s)
- Luis Alvarez
- Center of Advanced European Studies and Research (CAESAR), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - Benjamin M Friedrich
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - Gerhard Gompper
- Research Centre Jülich, Institute of Complex Systems (ICS-2), 52425 Jülich, Germany
| | - U Benjamin Kaupp
- Center of Advanced European Studies and Research (CAESAR), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
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109
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Shiba K, Shibata D, Inaba K. Autonomous changes in the swimming direction of sperm in the gastropod Strombus luhuanus. ACTA ACUST UNITED AC 2013; 217:986-96. [PMID: 24311809 DOI: 10.1242/jeb.095398] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The sperm of the gastropod Strombus luhuanus show dimorphism. The eusperm have a nucleus and fertilize the egg, whereas the other type of sperm, parasperm, are anucleate and are thought to assist fertilization. Here we report the autonomous changes in the swimming pattern of S. luhuanus eusperm. In artificial seawater, the eusperm collected from S. luhuanus sperm ducts formed sperm bundles and initially swam backward with asymmetric flagellar waveforms to detach from the bundles. One hour later, the sperm began to swim forward and in a circle. After an additional 1 h incubation, the sperm swam straight, with a change in the flagellar waveforms from asymmetric to symmetric. Spontaneous backward swimming with symmetric waveforms was also observed. The eusperm stored in the female seminal receptacle were motile and showed forward symmetric swimming with spontaneous backward swimming, which appeared necessary for detachment from the wall of receptacle. All of these motility changes were observed in the absence of parasperm, suggesting that these changes autonomously occur in eusperm. Our waveform analysis of these swimming patterns revealed that only the swimming with symmetric waveform showed reverse propagation of the flagellar waveforms. Both types of backward swimming were diminished in Ca(2+)-free seawater and in seawater containing Ni(2+), indicating the regulation of swimming direction by Ca(2+)-dependent signal transduction.
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Affiliation(s)
- Kogiku Shiba
- Shimoda Marine Research Center, University of Tsukuba, 5-10-1 Shimoda, Shizuoka 415-0025, Japan
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110
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CRIS-a novel cAMP-binding protein controlling spermiogenesis and the development of flagellar bending. PLoS Genet 2013; 9:e1003960. [PMID: 24339785 PMCID: PMC3854790 DOI: 10.1371/journal.pgen.1003960] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 09/30/2013] [Indexed: 12/17/2022] Open
Abstract
The second messengers cAMP and cGMP activate their target proteins by binding to a conserved cyclic nucleotide-binding domain (CNBD). Here, we identify and characterize an entirely novel CNBD-containing protein called CRIS (cyclic nucleotide receptor involved in sperm function) that is unrelated to any of the other members of this protein family. CRIS is exclusively expressed in sperm precursor cells. Cris-deficient male mice are either infertile due to a lack of sperm resulting from spermatogenic arrest, or subfertile due to impaired sperm motility. The motility defect is caused by altered Ca(2+) regulation of flagellar beat asymmetry, leading to a beating pattern that is reminiscent of sperm hyperactivation. Our results suggest that CRIS interacts during spermiogenesis with Ca(2+)-regulated proteins that--in mature sperm--are involved in flagellar bending.
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111
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van der Horst G, Maree L. Sperm form and function in the absence of sperm competition. Mol Reprod Dev 2013; 81:204-16. [DOI: 10.1002/mrd.22277] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 10/30/2013] [Indexed: 01/08/2023]
Affiliation(s)
- Gerhard van der Horst
- Department of Medical Bioscience; University of the Western Cape; Bellville South Africa
| | - Liana Maree
- Department of Medical Bioscience; University of the Western Cape; Bellville South Africa
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112
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Liu Z, Wang B, He R, Zhao Y, Miao L. Calcium signaling and the MAPK cascade are required for sperm activation in Caenorhabditis elegans. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:299-308. [PMID: 24239721 DOI: 10.1016/j.bbamcr.2013.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 10/28/2013] [Accepted: 11/05/2013] [Indexed: 12/20/2022]
Abstract
In nematode, sperm activation (or spermiogenesis), a process in which the symmetric and non-motile spermatids transform into polarized and crawling spermatozoa, is critical for sperm cells to acquire fertilizing competence. SPE-8 dependent and SPE-8 independent pathways function redundantly during sperm activation in both males and hermaphrodites of Caenorhabditis elegans. However, the downstream signaling for both pathways remains unclear. Here we show that calcium signaling and the MAPK cascade are required for both SPE-8 dependent and SPE-8 independent sperm activation, implying that both pathways share common downstream signaling components during sperm activation. We demonstrate that activation of the MAPK cascade is sufficient to activate spermatids derived from either wild-type or spe-8 group mutant males and that activation of the MAPK cascade bypasses the requirement of calcium signal to induce sperm activation, indicating that the MAPK cascade functions downstream of or parallel with the calcium signaling during sperm activation. Interestingly, the persistent activation of MAPK in activated spermatozoa inhibits Major Sperm Protein (MSP)-based cytoskeleton dynamics. We demonstrate that MAPK plays dual roles in promoting pseudopod extension during sperm activation but also blocking the MSP-based, amoeboid motility of the spermatozoa. Thus, though nematode sperm are crawling cells, morphologically distinct from flagellated sperm, and the molecular machinery for motility of amoeboid and flagellated sperm is different, both types of sperm might utilize conserved signaling pathways to modulate sperm maturation.
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Affiliation(s)
- Zhiyu Liu
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bin Wang
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ruijun He
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanmei Zhao
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Long Miao
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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113
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Abstract
We report the discovery of an entirely new three-dimensional (3D) swimming pattern observed in human and horse sperms. This motion is in the form of ‘chiral ribbons’, where the planar swing of the sperm head occurs on an osculating plane creating in some cases a helical ribbon and in some others a twisted ribbon. The latter, i.e., the twisted ribbon trajectory, also defines a minimal surface, exhibiting zero mean curvature for all the points on its surface. These chiral ribbon swimming patterns cannot be represented or understood by already known patterns of sperms or other micro-swimmers. The discovery of these unique patterns is enabled by holographic on-chip imaging of >33,700 sperm trajectories at >90–140 frames/sec, which revealed that only ~1.7% of human sperms exhibit chiral ribbons, whereas it increases to ~27.3% for horse sperms. These results might shed more light onto the statistics and biophysics of various micro-swimmers' 3D motion.
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114
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De Lisa E, Salzano AM, Moccia F, Scaloni A, Di Cosmo A. Sperm-attractant peptide influences the spermatozoa swimming behavior in internal fertilization in Octopus vulgaris. J Exp Biol 2013; 216:2229-37. [DOI: 10.1242/jeb.081885] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Marine invertebrates exhibit both chemokinesis and chemotaxis phenomena, induced in most cases by the release of water-borne peptides or pheromones. In mollusks, several peptides released during egg-laying improve both male attraction and mating. Unlike other cephalopods, Octopus vulgaris adopts an indirect internal fertilization strategy. We here report on the identification and characterization of a chemoattractant peptide isolated from mature eggs of octopus females. Using two-chamber and time-lapse microscopy assays, we demonstrate that this bioactive peptide is able to increase sperm motility and induce chemotaxis by changing the octopus spermatozoa swimming behavior in a dose-dependent manner. We also provide evidence that chemotaxis in the octopus requires the presence of extracellular calcium and membrane protein phophorylation at tyrosine. This study is the first report on a sperm-activating factor in a non-free-spawning marine animal.
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Affiliation(s)
- Emilia De Lisa
- Department of Structural and Functional Biology, University of Napoli ‘Federico II’, 80126 Napoli, Italy
| | - Anna Maria Salzano
- Proteomics and Mass Spectrometry Laboratory, ISPAAM, National Research Council, 80147 Naples, Italy
| | - Francesco Moccia
- Department of Biology and Biotechnology ‘Lazzaro Spallanzani’, Laboratory of Physiology, University of Pavia, 27100 Pavia, Italy
| | - Andrea Scaloni
- Proteomics and Mass Spectrometry Laboratory, ISPAAM, National Research Council, 80147 Naples, Italy
| | - Anna Di Cosmo
- Department of Structural and Functional Biology, University of Napoli ‘Federico II’, 80126 Napoli, Italy
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115
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Publicover S. Telling sperm to sort themselves out. Mol Hum Reprod 2013; 19:545-6. [PMID: 23741062 DOI: 10.1093/molehr/gat041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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116
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Shang Y, Chen L, Liu Z, Wang X, Ma X, Miao L. Cytosolic Ca(2+) as a multifunctional modulator is required for spermiogenesis in Ascaris suum. Protein Cell 2013; 4:456-66. [PMID: 23686736 DOI: 10.1007/s13238-013-3019-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 04/07/2013] [Indexed: 10/26/2022] Open
Abstract
The dynamic polar polymers actin filaments and microtubules are usually employed to provide the structural basis for establishing cell polarity in most eukaryotic cells. Radially round and immotile spermatids from nematodes contain almost no actin or tubulin, but still have the ability to break symmetry to extend a pseudopod and initiate the acquisition of motility powered by the dynamics of cytoskeleton composed of major sperm protein (MSP) during spermiogenesis (sperm activation). However, the signal transduction mechanism of nematode sperm activation and motility acquisition remains poorly understood. Here we show that Ca(2+) oscillations induced by the Ca(2+) release from intracellular Ca(2+) store through inositol (1,4,5)-trisphosphate receptor are required for Ascaris suum sperm activation. The chelation of cytosolic Ca(2+) suppresses the generation of a functional pseudopod, and this suppression can be relieved by introducing exogenous Ca(2+) into sperm cells. Ca(2+) promotes MSP-based sperm motility by increasing mitochondrial membrane potential and thus the energy supply required for MSP cytoskeleton assembly. On the other hand, Ca(2+) promotes MSP disassembly by activating Ca(2+)/calmodulin-dependent serine/threonine protein phosphatase calcineurin. In addition, Ca(2+)/camodulin activity is required for the fusion of sperm-specifi c membranous organelle with the plasma membrane, a regulated exocytosis required for sperm motility. Thus, Ca(2+) plays multifunctional roles during sperm activation in Ascaris suum.
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Affiliation(s)
- Yunlong Shang
- Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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117
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Chang H, Kim BJ, Kim YS, Suarez SS, Wu M. Different migration patterns of sea urchin and mouse sperm revealed by a microfluidic chemotaxis device. PLoS One 2013; 8:e60587. [PMID: 23613731 PMCID: PMC3628882 DOI: 10.1371/journal.pone.0060587] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 02/28/2013] [Indexed: 12/17/2022] Open
Abstract
Chemotaxis refers to a process whereby cells move up or down a chemical gradient. Sperm chemotaxis is known to be a strategy exploited by marine invertebrates such as sea urchins to reach eggs efficiently in moving water. Less is understood about how or whether chemotaxis is used by mammalian sperm to reach eggs, where fertilization takes place within the confinement of a reproductive tract. In this report, we quantitatively assessed sea urchin and mouse sperm chemotaxis using a recently developed microfluidic model and high-speed imaging. Results demonstrated that sea urchin Arbacia punctulata sperm were chemotactic toward the peptide resact with high chemotactic sensitivity, with an average velocity Vx up the chemical gradient as high as 20% of its average speed (238 μm/s), while mouse sperm displayed no statistically significant chemotactic behavior in progesterone gradients, which had been proposed to guide mammalian sperm toward eggs. This work demonstrates the validity of a microfluidic model for quantitative sperm chemotaxis studies, and reveals a biological insight that chemotaxis up a progesterone gradient may not be a universal strategy for mammalian sperm to reach eggs.
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Affiliation(s)
- Haixin Chang
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - Beum Jun Kim
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, United States of America
| | - Yoon Soo Kim
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, United States of America
| | - Susan S. Suarez
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
- * E-mail: (SSS); (MW)
| | - Mingming Wu
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, United States of America
- * E-mail: (SSS); (MW)
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118
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Chen SJ, Allam JP, Duan YG, Haidl G. Influence of reactive oxygen species on human sperm functions and fertilizing capacity including therapeutical approaches. Arch Gynecol Obstet 2013; 288:191-9. [PMID: 23543240 DOI: 10.1007/s00404-013-2801-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 03/12/2013] [Indexed: 12/31/2022]
Abstract
BACKGROUND Reactive oxygen species (ROS) are an array of molecules including oxygen-centered radicals, which are endowed with one or more unpaired electrons and non-radical oxygen derivatives such as hydrogen peroxide, which behave, to a large extent, like a double-edged sword in human sperm biology. This study aimed to overview the current knowledge of ROS in sperm physiology and pathology, as well as related therapies in spermatozoal dysfunction. METHODS We performed this study by searching for keywords from PUBMED, including reactive oxygen species, oxidative stress, sperm function, and antioxidant therapy. RESULTS AND CONCLUSIONS Low levels of ROS exert critical function in normal sperm physiology, such as fertilizing ability (acrosome reaction, hyperactivation, capacitation, and chemotaxis) and sperm motility; while increased ROS generation and/or decreased antioxidant capacity leads to the imbalance between oxidation and reduction in living systems, which is called sperm oxidative stress. This condition was widely considered to be a significant contributory factor to sperm DNA damage/apoptosis, lipid peroxidation, and reduced motility, which in turn, increased risk of male factor infertility/subfertility and birth defects. Under the current status quo, numerous subsequent studies have concentrated on antioxidant therapy. Although utility of such a therapeutic strategy significantly improved sperm function and motility in a myriad of experimental and clinical reports, the overall effectiveness still remains controversial mainly due to non-standardized assay to measure the level of ROS and sperm DNA damage, various antioxidant supplementation strategies, and inadequate fertilization and pregnancy data after clinical treatment. Therefore, standardized assessment and evaluation of ROS and total antioxidant capacity in semen should be established to keep ROS in a physiological level and prevent over-treatment of antioxidants toward reductive stress, which should be kept in mind, especially in assisted reproductive procedure. Moreover, the significance of large sample size populations, double-blind randomized, placebo-controlled clinical trials of antioxidant therapies is emphasized in this review to achieve optimal ingredients and dosage of antioxidants for patients with reactive oxygen-induced male fertility/subfertility.
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Affiliation(s)
- Shu-Jian Chen
- Department of Dermatology/Andrology Unit, Rheinische Friedrich-Wilhelms University, 53105 Bonn, Germany
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119
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Decreased Perception of Bourgeonal May Be Linked to Male Idiopathic Infertility. Chem Senses 2013; 38:439-45. [DOI: 10.1093/chemse/bjt009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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120
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Miki K, Clapham DE. Rheotaxis guides mammalian sperm. Curr Biol 2013; 23:443-52. [PMID: 23453951 DOI: 10.1016/j.cub.2013.02.007] [Citation(s) in RCA: 260] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 01/23/2013] [Accepted: 02/04/2013] [Indexed: 01/17/2023]
Abstract
BACKGROUND In sea urchins, spermatozoan motility is altered by chemotactic peptides, giving rise to the assumption that mammalian eggs also emit chemotactic agents that guide spermatozoa through the female reproductive tract to the mature oocyte. Mammalian spermatozoa indeed undergo complex adaptations within the female (the process of capacitation) that are initiated by agents ranging from pH to progesterone, but these factors are not necessarily taxic. Currently, chemotaxis, thermotaxis, and rheotaxis have not been definitively established in mammals. RESULTS Here, we show that positive rheotaxis, the ability of organisms to orient and swim against the flow of surrounding fluid, is a major taxic factor for mouse and human sperm. This flow is generated within 4 hr of sexual stimulation and coitus in female mice; prolactin-triggered oviductal fluid secretion clears the oviduct of debris, lowers viscosity, and generates the stream that guides sperm migration in the oviduct. Rheotaxic movement is demonstrated in capacitated and uncapacitated spermatozoa in low- and high-viscosity media. Finally, we show that a unique sperm motion, which we quantify using the sperm head's rolling rate, reflects sperm rotation that generates essential force for positioning the sperm in the stream. Rotation requires CatSper channels, presumably by enabling Ca(2+) influx. CONCLUSIONS We propose that rheotaxis is a major determinant of sperm guidance over long distances in the mammalian female reproductive tract. Coitus induces fluid flow to guide sperm in the oviduct. Sperm rheotaxis requires rotational motion during CatSper channel-dependent hyperactivated motility.
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Affiliation(s)
- Kiyoshi Miki
- Howard Hughes Medical Institute, Department of Cardiology, Manton Center for Orphan Disease Research, Boston Children's Hospital, 320 Longwood Avenue, Enders 1309, Boston, MA 02115, USA
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121
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Kashikar ND, Alvarez L, Seifert R, Gregor I, Jäckle O, Beyermann M, Krause E, Kaupp UB. Temporal sampling, resetting, and adaptation orchestrate gradient sensing in sperm. ACTA ACUST UNITED AC 2013; 198:1075-91. [PMID: 22986497 PMCID: PMC3444779 DOI: 10.1083/jcb.201204024] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Sperm use temporal sampling, resetting of intracellular calcium level, and adaptation of their sensitivity to respond to a wide range of chemoattractant concentrations during their voyage toward the egg. Sperm, navigating in a chemical gradient, are exposed to a periodic stream of chemoattractant molecules. The periodic stimulation entrains Ca2+ oscillations that control looping steering responses. It is not known how sperm sample chemoattractant molecules during periodic stimulation and adjust their sensitivity. We report that sea urchin sperm sampled molecules for 0.2–0.6 s before a Ca2+ response was produced. Additional molecules delivered during a Ca2+ response reset the cell by causing a pronounced Ca2+ drop that terminated the response; this reset was followed by a new Ca2+ rise. After stimulation, sperm adapted their sensitivity following the Weber–Fechner law. Taking into account the single-molecule sensitivity, we estimate that sperm can register a minimal gradient of 0.8 fM/µm and be attracted from as far away as 4.7 mm. Many microorganisms sense stimulus gradients along periodic paths to translate a spatial distribution of the stimulus into a temporal pattern of the cell response. Orchestration of temporal sampling, resetting, and adaptation might control gradient sensing in such organisms as well.
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Affiliation(s)
- Nachiket D Kashikar
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, 53175 Bonn, Germany
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122
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Hoang HD, Prasain JK, Dorand D, Miller MA. A heterogeneous mixture of F-series prostaglandins promotes sperm guidance in the Caenorhabditis elegans reproductive tract. PLoS Genet 2013; 9:e1003271. [PMID: 23382703 PMCID: PMC3561059 DOI: 10.1371/journal.pgen.1003271] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 12/10/2012] [Indexed: 11/25/2022] Open
Abstract
The mechanisms that guide motile sperm through the female reproductive tract to oocytes are not well understood. We have shown that Caenorhabditis elegans oocytes synthesize sperm guiding F-series prostaglandins from polyunsaturated fatty acid (PUFA) precursors provided in yolk lipoprotein complexes. Here we use genetics and electrospray ionization tandem mass spectrometry to partially delineate F-series prostaglandin metabolism pathways. We show that omega-6 and omega-3 PUFAs, including arachidonic and eicosapentaenoic acids, are converted into more than 10 structurally related F-series prostaglandins, which function collectively and largely redundantly to promote sperm guidance. Disruption of omega-3 PUFA synthesis triggers compensatory up-regulation of prostaglandins derived from omega-6 PUFAs. C. elegans F-series prostaglandin synthesis involves biochemical mechanisms distinct from those in mammalian cyclooxygenase-dependent pathways, yet PGF2α stereoisomers are still synthesized. A comparison of F-series prostaglandins in C. elegans and mouse tissues reveals shared features. Finally, we show that a conserved cytochrome P450 enzyme, whose human homolog is implicated in Bietti's Crystalline Dystrophy, negatively regulates prostaglandin synthesis. These results support the model that multiple cyclooxygenase-independent prostaglandins function together to promote sperm motility important for fertilization. This cyclooxygenase-independent pathway for F-series synthesis may be conserved. A fundamental question in cell and developmental biology is how motile cells find their target destinations. One of the most important cell targeting mechanisms involves the sperm and oocyte, which unite during fertilization to produce the next generation of offspring. We have been using the nematode C. elegans to delineate these mechanisms. Our prior studies have shown that oocytes secrete F-series prostaglandins that stimulate sperm motility. Prostaglandins are widespread signaling molecules derived from polyunsaturated fatty acids or PUFAs. Mammals are not capable of synthesizing PUFAs and must receive them in the diet. C. elegans was not thought to synthesize prostaglandins because the genome lacks cyclooxygenases, enzymes that catalyze the rate-limiting step in mammalian prostaglandin synthesis. Here we show that C. elegans oocytes synthesize a heterogenous mixture of structurally related F-series prostaglandins derived from different PUFA classes, including the enantiomer of PGF2α. These prostaglandins function collectively and redundantly to guide sperm to the fertilization site. Our results indicate that F-series prostaglandins can be synthesized independent of cyclooxygenase enzymes. This novel pathway may be evolutionarily conserved. Evidence is emerging that prostaglandins regulate sperm motility in the female reproductive tract of humans.
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Affiliation(s)
- Hieu D. Hoang
- Department of Cell Biology, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Jeevan K. Prasain
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Dixon Dorand
- Department of Cell Biology, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Michael A. Miller
- Department of Cell Biology, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
- * E-mail:
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123
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Abstract
Sperm intracellular pH and calcium concentration ([Ca(2+)]i) are two central factors that control sperm activity within the female reproductive tract. As such, the ion channels of the sperm plasma membrane that alter intracellular sperm [Ca(2+)] and pH play important roles in sperm physiology and the process of fertilization. Indeed, sperm ion channels regulate sperm motility, control sperm chemotaxis toward the egg in some species, and may trigger the acrosome reaction. Until recently, our understanding of these important molecules was rudimentary due to the inability to patch-clamp spermatozoa and directly record the activity of these ion channels under voltage clamp. Recently, we overcame this technical barrier and developed a method for reproducible application of the patch-clamp technique to mouse and human spermatozoa. This chapter covers important aspects of application of the patch-clamp technique to spermatozoa, such as selection of the electrophysiological equipment, isolation of spermatozoa for patch-clamp experiments, formation of the gigaohm seal with spermatozoa, and transition into the whole-cell mode of recording. We also discuss potential pitfalls in application of the patch-clamp technique to flagellar ion channels.
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Affiliation(s)
- Polina Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA.
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124
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Abstract
To succeed in fertilization, spermatozoa must decode environmental cues which require a set of ion channels. Recent findings have revealed that K(+) and Cl(-) channels participate in some of the main sperm functions. This work reviews the evidence indicating the involvement of K(+) and Cl(-) channels in motility, maturation, and the acrosome reaction, and the advancement in identifying their molecular identity and modes of regulation. Improving our insight on how these channels operate will strengthen our ability to surmount some infertility problems, improve animal breeding, preserve biodiversity, and develop selective and secure male contraceptives.
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125
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Guerrero A, Espinal J, Wood CD, Rendón JM, Carneiro J, Martínez-Mekler G, Darszon A. Niflumic acid disrupts marine spermatozoan chemotaxis without impairing the spatiotemporal detection of chemoattractant gradients. J Cell Sci 2013; 126:1477-87. [DOI: 10.1242/jcs.121442] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In many broadcast-spawning marine organisms, oocytes release chemicals that guide conspecific spermatozoa towards their source through chemotaxis. In the sea urchin Lytechinus pictus, the chemoattractant peptide speract triggers a train of fluctuations of intracellular Ca2+ concentration in the sperm flagella. Each transient Ca2+ elevation leads to a momentary increase in flagellar bending asymmetry, known as a chemotactic turn. Furthermore, chemotaxis requires a precise spatiotemporal coordination between the Ca2+-dependent turns and the form of chemoattractant gradient. Spermatozoa that display Ca2+-dependent turns while swimming down the chemoattractant gradient, and conversely suppress turning events while swimming up gradient, successfully approach the center of the gradient. Previous experiments in Strongylocentrotus purpuratus sea urchin spermatozoa showed that niflumic acid (NFA), an inhibitor of several ion channels, drastically altered the speract-induced Ca2+ fluctuations and swimming patterns. In this study, mathematical modeling of the speract-dependent Ca2+ signaling pathway suggests that NFA, by potentially affecting HCN, CaCC and CaKC channels, may alter the temporal organization of Ca2+ fluctuations, and therefore disrupt chemotaxis. Here we investigate our hypothesis using a novel automated method for analyzing sperm behavior. We show that NFA does indeed disrupt chemotactic responses of L. pictus spermatozoa, although the temporal coordination between the Ca2+-dependent turns and the form of chemoattractant gradient is unaltered. Instead, NFA disrupts sperm chemotaxis by altering the arc length traveled during each chemotactic turning event. This alteration in the chemotactic turn trajectory disorientates spermatozoa at the termination of the turning event. We conclude that NFA disrupts chemotaxis without affecting how the spermatozoa decode environmental cues.
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126
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Fluid dynamic model of invertebrate sperm chemotactic motility with varying calcium inputs. J Biomech 2012; 46:329-37. [PMID: 23218141 DOI: 10.1016/j.jbiomech.2012.11.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 11/09/2012] [Indexed: 12/29/2022]
Abstract
In a marine environment, invertebrate sperm are able to adjust their trajectory in response to a gradient of chemical factors released by the egg in a process called chemotaxis. In response to this chemical factor, a signaling cascade is initiated that causes an increase in intracellular calcium (Ca(2+)). This increase in Ca(2+) causes the sperm flagellar curvature to change, and a change in swimming direction ensues. In previous experiments, sperm swimming in a gradient of chemoattractant have exhibited Ca(2+) oscillations of varying peaks and frequency. Here, we model a simplified sperm flagellum with mechanical forces, including a passive stiffness component and an active bending component that is coupled to the time varying Ca(2+) input. The flagellum is immersed in a viscous, incompressible fluid and we use a fluid dynamic model to investigate emergent trajectories. We investigate the sensitivity of the model to the frequency of Ca(2+) oscillations. In this coupled model, we observe that longer periods of Ca(2+) oscillation corresponds to circular paths with greater drift. In contrast, shorter periods of Ca(2+) oscillations corresponded to tighter search patterns. These outcomes shed light on the relation between Ca(2+) oscillations and different searching trajectories and strategies that invertebrate sperm may utilize to reach and fertilize the egg in a marine environment.
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127
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Aguilera LU, Galindo BE, Sánchez D, Santillán M. What is the core oscillator in the speract-activated pathway of the Strongylocentrotus purpuratus sperm flagellum? Biophys J 2012; 102:2481-8. [PMID: 22713563 DOI: 10.1016/j.bpj.2012.03.075] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 03/06/2012] [Accepted: 03/29/2012] [Indexed: 12/31/2022] Open
Abstract
Sperm chemotaxis has an important role in fertilization. Most of our knowledge regarding this phenomenon comes from studies in organisms whose fertilization occurs externally, like sea urchins. Sea urchin spermatozoa respond to sperm-activating peptides, which diffuse from the egg jelly coat and interact with their receptor in the flagellum, triggering several physiological responses: changes in membrane potential, intracellular pH, cyclic nucleotide levels, and intracellular Ca2+ concentration ([Ca2+]). In particular, flagellar [Ca2+] has been shown to oscillate. These [Ca2+] oscillations are correlated with changes in the flagellar shape and so with the regulation of the sperm swimming paths. In this study, we demonstrate, from a mathematical modeling perspective, that the reported speract-activated signaling pathway in Strongylocentrotus purpuratus (speract being a sperm-activating peptide specific to this species) has the necessary elements to replicate the reported [Ca2+] oscillations. We further investigate which elements of this signaling pathway constitute the core oscillator.
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Affiliation(s)
- Luis U Aguilera
- Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Monterrey, Parque de Investigación e Innovación Tecnológica, Apodaca, Mexico
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128
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Caille AM, Berta CL, Cuasnicú PS, Munuce MJ. Peritoneal fluid modifies the response of human spermatozoa to follicular fluid. Reprod Biomed Online 2012; 24:466-73. [DOI: 10.1016/j.rbmo.2011.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 12/14/2011] [Accepted: 12/22/2011] [Indexed: 01/10/2023]
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129
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Casas I, Torner E, Yeste M, Bonet S. Boar sperm thawing practices: The number of straws does matter. Theriogenology 2012; 77:1487-94. [DOI: 10.1016/j.theriogenology.2011.10.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 10/28/2011] [Accepted: 10/30/2011] [Indexed: 10/14/2022]
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130
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Armon L, Caplan SR, Eisenbach M, Friedrich BM. Testing human sperm chemotaxis: how to detect biased motion in population assays. PLoS One 2012; 7:e32909. [PMID: 22412947 PMCID: PMC3297605 DOI: 10.1371/journal.pone.0032909] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 02/07/2012] [Indexed: 11/24/2022] Open
Abstract
Biased motion of motile cells in a concentration gradient of a chemoattractant is frequently studied on the population level. This approach has been particularly employed in human sperm chemotactic assays, where the fraction of responsive cells is low and detection of biased motion depends on subtle differences. In these assays, statistical measures such as population odds ratios of swimming directions can be employed to infer chemotactic performance. Here, we report on an improved method to assess statistical significance of experimentally determined odds ratios and discuss the strong impact of data correlations that arise from the directional persistence of sperm swimming.
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Affiliation(s)
- Leah Armon
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - S. Roy Caplan
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Michael Eisenbach
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Benjamin M. Friedrich
- Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, Israel
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- * E-mail:
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131
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Meyer D, Voigt A, Widmayer P, Borth H, Huebner S, Breit A, Marschall S, de Angelis MH, Boehm U, Meyerhof W, Gudermann T, Boekhoff I. Expression of Tas1 taste receptors in mammalian spermatozoa: functional role of Tas1r1 in regulating basal Ca²⁺ and cAMP concentrations in spermatozoa. PLoS One 2012; 7:e32354. [PMID: 22427794 PMCID: PMC3303551 DOI: 10.1371/journal.pone.0032354] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 01/25/2012] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND During their transit through the female genital tract, sperm have to recognize and discriminate numerous chemical compounds. However, our current knowledge of the molecular identity of appropriate chemosensory receptor proteins in sperm is still rudimentary. Considering that members of the Tas1r family of taste receptors are able to discriminate between a broad diversity of hydrophilic chemosensory substances, the expression of taste receptors in mammalian spermatozoa was examined. METHODOLOGY/PRINCIPAL FINDINGS The present manuscript documents that Tas1r1 and Tas1r3, which form the functional receptor for monosodium glutamate (umami) in taste buds on the tongue, are expressed in murine and human spermatozoa, where their localization is restricted to distinct segments of the flagellum and the acrosomal cap of the sperm head. Employing a Tas1r1-deficient mCherry reporter mouse strain, we found that Tas1r1 gene deletion resulted in spermatogenic abnormalities. In addition, a significant increase in spontaneous acrosomal reaction was observed in Tas1r1 null mutant sperm whereas acrosomal secretion triggered by isolated zona pellucida or the Ca²⁺ ionophore A23187 was not different from wild-type spermatozoa. Remarkably, cytosolic Ca²⁺ levels in freshly isolated Tas1r1-deficient sperm were significantly higher compared to wild-type cells. Moreover, a significantly higher basal cAMP concentration was detected in freshly isolated Tas1r1-deficient epididymal spermatozoa, whereas upon inhibition of phosphodiesterase or sperm capacitation, the amount of cAMP was not different between both genotypes. CONCLUSIONS/SIGNIFICANCE Since Ca²⁺ and cAMP control fundamental processes during the sequential process of fertilization, we propose that the identified taste receptors and coupled signaling cascades keep sperm in a chronically quiescent state until they arrive in the vicinity of the egg - either by constitutive receptor activity and/or by tonic receptor activation by gradients of diverse chemical compounds in different compartments of the female reproductive tract.
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MESH Headings
- Animals
- Blotting, Western
- Calcium/metabolism
- Cyclic AMP/metabolism
- Female
- Gene Expression
- Humans
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Male
- Mice
- Mice, 129 Strain
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Microscopy, Confocal
- Models, Biological
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Rats, Wistar
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, G-Protein-Coupled/physiology
- Reverse Transcriptase Polymerase Chain Reaction
- Sperm Head/metabolism
- Spermatozoa/metabolism
- Testis/cytology
- Testis/metabolism
- Red Fluorescent Protein
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Affiliation(s)
- Dorke Meyer
- Walther-Straub Institute of Pharmacology and
Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Anja Voigt
- German Institute of Nutrition,
Potsdam-Rehbruecke, Germany
- Institute for Neural Signal Transduction,
Center for Molecular Neurobiology, Hamburg, Germany
| | - Patricia Widmayer
- Institute of Physiology, University of
Hohenheim, Stuttgart, Germany
| | - Heike Borth
- Walther-Straub Institute of Pharmacology and
Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Sandra Huebner
- German Institute of Nutrition,
Potsdam-Rehbruecke, Germany
| | - Andreas Breit
- Walther-Straub Institute of Pharmacology and
Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Susan Marschall
- Institute of Experimental Genetics,
Helmholtz-Zentrum, Munich, Germany
| | | | - Ulrich Boehm
- Institute for Neural Signal Transduction,
Center for Molecular Neurobiology, Hamburg, Germany
| | | | - Thomas Gudermann
- Walther-Straub Institute of Pharmacology and
Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Ingrid Boekhoff
- Walther-Straub Institute of Pharmacology and
Toxicology, Ludwig-Maximilians-University, Munich, Germany
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132
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Alvarez L, Dai L, Friedrich BM, Kashikar ND, Gregor I, Pascal R, Kaupp UB. The rate of change in Ca(2+) concentration controls sperm chemotaxis. ACTA ACUST UNITED AC 2012; 196:653-63. [PMID: 22371558 PMCID: PMC3307702 DOI: 10.1083/jcb.201106096] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sperm navigate in a chemoattractant gradient by translating changes in intracellular calcium concentration over time into changes in curvature of the swimming path. During chemotaxis and phototaxis, sperm, algae, marine zooplankton, and other microswimmers move on helical paths or drifting circles by rhythmically bending cell protrusions called motile cilia or flagella. Sperm of marine invertebrates navigate in a chemoattractant gradient by adjusting the flagellar waveform and, thereby, the swimming path. The waveform is periodically modulated by Ca2+ oscillations. How Ca2+ signals elicit steering responses and shape the path is unknown. We unveil the signal transfer between the changes in intracellular Ca2+ concentration ([Ca2+]i) and path curvature (κ). We show that κ is modulated by the time derivative d[Ca2+]i/dt rather than the absolute [Ca2+]i. Furthermore, simulation of swimming paths using various Ca2+ waveforms reproduces the wealth of swimming paths observed for sperm of marine invertebrates. We propose a cellular mechanism for a chemical differentiator that computes a time derivative. The cytoskeleton of cilia, the axoneme, is highly conserved. Thus, motile ciliated cells in general might use a similar cellular computation to translate changes of [Ca2+]i into motion.
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Affiliation(s)
- Luis Alvarez
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research (caesar), 53175 Bonn, Germany.
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133
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Burnett LA, Sugiyama H, Bieber AL, Chandler DE. Egg jelly proteins stimulate directed motility in Xenopus laevis sperm. Mol Reprod Dev 2012; 78:450-62. [PMID: 21692128 DOI: 10.1002/mrd.21325] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Previously we have shown that extracts from Xenopus egg jelly (egg water) increase the passage of sperm through a porous membrane in a dose-dependent manner. Although this assay has shown that sperm accumulation occurs only in the presence of an egg water gradient, it has not revealed the dynamic features of how Xenopus sperm swim in such gradients. Here, we use video microscopic observations to trace sperm trajectories in a Zigmond chamber. Our results show that Xenopus sperm swim in linear and gently curving paths and only infrequently perform turns. In the presence of an egg water gradient, however, the percent of sperm swimming up the gradient axis and the net distance traveled by each sperm along this axis was increased significantly. There was no change in curvilinear velocity. Rather, the orientation of sperm travel was shifted to more closely match that of the gradient axis. In addition, using a porous filter assay, we demonstrate that the egg water protein allurin, in both purified and recombinant forms, stimulates directed motility of sperm. Finally, we use Oregon Green 488-conjugated allurin to show that this protein binds primarily to the sperm midpiece; binding of allurin to the entire head was observed in a minor subpopulation of sperm. Dose dependence of allurin binding occurred over the 0-1 µg/ml range and correlated well with previously published dose-dependent sperm attraction data. Binding was rapid with a half-time of about 10 sec. These data suggest that egg water proteins bind to sperm and modify sperm-orienting behavior.
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Affiliation(s)
- Lindsey A Burnett
- Molecular and Cellular Biology Program, School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501, USA
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134
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The CatSper channel: a polymodal chemosensor in human sperm. EMBO J 2012; 31:1654-65. [PMID: 22354039 DOI: 10.1038/emboj.2012.30] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 01/18/2012] [Indexed: 01/10/2023] Open
Abstract
The sperm-specific CatSper channel controls the intracellular Ca(2+) concentration ([Ca(2+)](i)) and, thereby, the swimming behaviour of sperm. In humans, CatSper is directly activated by progesterone and prostaglandins-female factors that stimulate Ca(2+) influx. Other factors including neurotransmitters, chemokines, and odorants also affect sperm function by changing [Ca(2+)](i). Several ligands, notably odorants, have been proposed to control Ca(2+) entry and motility via G protein-coupled receptors (GPCRs) and cAMP-signalling pathways. Here, we show that odorants directly activate CatSper without involving GPCRs and cAMP. Moreover, membrane-permeable analogues of cyclic nucleotides that have been frequently used to study cAMP-mediated Ca(2+) signalling also activate CatSper directly via an extracellular site. Thus, CatSper or associated protein(s) harbour promiscuous binding sites that can host various ligands. These results contest current concepts of Ca(2+) signalling by GPCR and cAMP in mammalian sperm: ligands thought to activate metabotropic pathways, in fact, act via a common ionotropic mechanism. We propose that the CatSper channel complex serves as a polymodal sensor for multiple chemical cues that assist sperm during their voyage across the female genital tract.
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135
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Evolutionary genomics reveals the premetazoan origin of opposite gating polarity in animal-type voltage-gated ion channels. Genomics 2012; 99:241-5. [PMID: 22326743 DOI: 10.1016/j.ygeno.2012.01.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 01/21/2012] [Accepted: 01/26/2012] [Indexed: 11/22/2022]
Abstract
Electrical signaling in animals ensures the rapid and accurate transmission of information, often carried by voltage-gated Na(+), Ca(2+) and K(+) channels that are activated by membrane depolarization. In heart and neurons, a distinct type of ion channel called the hyperpolarization-activated, cyclic nucleotide-regulated (HCN) channel is activated by membrane hyperpolarization. Recent genomic studies have revealed that animal-type voltage-gated Na(+) channels (Liebeskind BJ, et al. 2011. Proc Natl Acad Sci U S A. 108:9154) had evolved in choanoflagellates, one of the unicellular relatives of animals. To date, HCN channels have been considered to be animal-specific. Here, we demonstrate the presence of an HCN channel homolog (SroHCN) in the choanoflagellate protist Salpingoeca rosetta. SroHCN contains highly conserved functional domains and sequence motifs that are correlated with the unique biophysical activities of HCN channels. These findings provide novel genomic insights into the evolution of complex electrical signaling before the emergence of multicellular animals.
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136
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Beirão J, Zilli L, Vilella S, Cabrita E, Schiavone R, Herráez MP. Improving Sperm Cryopreservation with Antifreeze Proteins: Effect on Gilthead Seabream (Sparus aurata) Plasma Membrane Lipids1. Biol Reprod 2012; 86:59. [DOI: 10.1095/biolreprod.111.093401] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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137
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KO YJ, MAENG JH, LEE BC, LEE S, HWANG SY, AHN Y. Separation of Progressive Motile Sperm from Mouse Semen Using On-chip Chemotaxis. ANAL SCI 2012; 28:27-32. [DOI: 10.2116/analsci.28.27] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Yong-Jun KO
- Department of Mechanical Engineering, Graduate School, Hanyang University
| | - Joon-Ho MAENG
- Department of Biochemistry, Graduate School, Hanyang University
| | - Byung-Chul LEE
- Department of Biochemistry, Graduate School, Hanyang University
| | - Seungwoo LEE
- Department of Mechanical Engineering, Graduate School, Hanyang University
| | - Seung Yong HWANG
- Division of Molecular and Life Science, Hanyang University and GenoCheck Co. Ltd
| | - Yoomin AHN
- Department of Mechanical Engineering, Hanyang University
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138
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Burnett LA, Washburn CA, Sugiyama H, Xiang X, Olson JH, Al-Anzi B, Bieber AL, Chandler DE. Allurin, an amphibian sperm chemoattractant having implications for mammalian sperm physiology. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 295:1-61. [PMID: 22449486 DOI: 10.1016/b978-0-12-394306-4.00007-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Eggs of many species are surrounded by extracellular coats that emit ligands to which conspecific sperm respond by undergoing chemotaxis and changes in metabolism, motility, and acrosomal status in preparation for fertilization. Here we review methods used to measure sperm chemotaxis and focus on recent studies of allurin, a 21-kDa protein belonging to the Cysteine-RIch Secretory Protein (CRISP) family that has chemoattraction activity for both amphibian and mammalian sperm. Allurin is unique in being the first extensively characterized Crisp protein found in the female reproductive tract and is the product of a newly discovered amphibian gene within a gene cluster that has been largely conserved in mammals. Study of its expression, function, and tertiary structure could lead to new insights in the role of Crisp proteins in sperm physiology.
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Affiliation(s)
- Lindsey A Burnett
- Department of Animal Science, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA
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139
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Konno A, Setou M, Ikegami K. Ciliary and flagellar structure and function--their regulations by posttranslational modifications of axonemal tubulin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 294:133-70. [PMID: 22364873 DOI: 10.1016/b978-0-12-394305-7.00003-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Eukaryotic cilia and flagella are evolutionarily conserved microtubule-based organelles protruding from the cell surface. They perform dynein-driven beating which contributes to cell locomotion or flow generation. They also play important roles in sensing as cellular antennae, which allows cells to respond to various external stimuli. The main components of cilia and flagella, α- and β-tubulins, are known to undergo various posttranslational modifications (PTMs), including phosphorylation, palmitoylation, tyrosination/detyrosination, Δ2 modification, acetylation, glutamylation, and glycylation. Recent identification of tubulin-modifying enzymes, especially tubulin tyrosine ligase-like proteins which perform tubulin glutamylation and glycylation, has demonstrated the importance of tubulin modifications for the assembly and functions of cilia and flagella. In this chapter, we review recent work on PTMs of ciliary and flagellar tubulins in conjunction with discussing the basic knowledge.
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Affiliation(s)
- Alu Konno
- Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, Hamamatsu, Japan
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140
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Sperm preparation: state-of-the-art--physiological aspects and application of advanced sperm preparation methods. Asian J Androl 2011; 14:260-9. [PMID: 22138904 DOI: 10.1038/aja.2011.133] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
For assisted reproduction technologies (ART), numerous techniques were developed to isolate spermatozoa capable of fertilizing oocytes. While early methodologies only focused on isolating viable, motile spermatozoa, with progress of ART, particularly intracytoplasmic sperm injection (ICSI), it became clear that these parameters are insufficient for the identification of the most suitable spermatozoon for fertilization. Conventional sperm preparation techniques, namely, swim-up, density gradient centrifugation and glass wool filtration, are not efficient enough to produce sperm populations free of DNA damage, because these techniques are not physiological and not modeled on the stringent sperm selection processes taking place in the female genital tract. These processes only allow one male germ cell out of tens of millions to fuse with the oocyte. Sites of sperm selection in the female genital tract are the cervix, uterus, uterotubal junction, oviduct, cumulus oophorus and the zona pellucida. Newer strategies of sperm preparation are founded on: (i) morphological assessment by means of 'motile sperm organelle morphological examination (MSOME)'; (ii) electrical charge; and (iii) molecular binding characteristics of the sperm cell. Whereas separation methods based on electrical charge take advantage of the sperm's adherence to a test tube surface or separate in an electrophoresis, molecular binding techniques use Annexin V or hyaluronic acid (HA) as substrates. Techniques in this category are magnet-activated cell sorting, Annexin V-activated glass wool filtration, flow cytometry and picked spermatozoa for ICSI (PICSI) from HA-coated dishes and HA-containing media. Future developments may include Raman microspectrometry, confocal light absorption and scattering spectroscopic microscopy and polarization microscopy.
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141
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PIMENTEL J, CARNEIRO J, DARSZON A, CORKIDI G. A segmentation algorithm for automated tracking of fast swimming unlabelled cells in three dimensions. J Microsc 2011; 245:72-81. [DOI: 10.1111/j.1365-2818.2011.03545.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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142
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Lishko PV, Kirichok Y, Ren D, Navarro B, Chung JJ, Clapham DE. The control of male fertility by spermatozoan ion channels. Annu Rev Physiol 2011; 74:453-75. [PMID: 22017176 DOI: 10.1146/annurev-physiol-020911-153258] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ion channels control the sperm ability to fertilize the egg by regulating sperm maturation in the female reproductive tract and by triggering key sperm physiological responses required for successful fertilization such as hyperactivated motility, chemotaxis, and the acrosome reaction. CatSper, a pH-regulated, calcium-selective ion channel, and KSper (Slo3) are core regulators of sperm tail calcium entry and sperm hyperactivated motility. Many other channels had been proposed as regulating sperm activity without direct measurements. With the development of the sperm patch-clamp technique, CatSper and KSper have been confirmed as the primary spermatozoan ion channels. In addition, the voltage-gated proton channel Hv1 has been identified in human sperm tail, and the P2X2 ion channel has been identified in the midpiece of mouse sperm. Mutations and deletions in sperm-specific ion channels affect male fertility in both mice and humans without affecting other physiological functions. The uniqueness of sperm ion channels makes them ideal pharmaceutical targets for contraception. In this review we discuss how ion channels regulate sperm physiology.
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Affiliation(s)
- Polina V Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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143
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Burnett LA, Anderson DM, Rawls A, Bieber AL, Chandler DE. Mouse sperm exhibit chemotaxis to allurin, a truncated member of the cysteine-rich secretory protein family. Dev Biol 2011; 360:318-28. [PMID: 22008793 DOI: 10.1016/j.ydbio.2011.09.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 09/23/2011] [Accepted: 09/26/2011] [Indexed: 12/14/2022]
Abstract
Allurin, a 21 kDa protein isolated from egg jelly of the frog Xenopus laevis, has previously been demonstrated to attract frog sperm in two-chamber and microscopic assays. cDNA cloning and sequencing has shown that allurin is a truncated member of the Cysteine-Rich Secretory Protein (CRISP) family, whose members include mammalian sperm-binding proteins that have been postulated to play roles in spermatogenesis, sperm capacitation and sperm-egg binding in mammals. Here, we show that allurin is a chemoattractant for mouse sperm, as determined by a 2.5-fold stimulation of sperm passage across a porous membrane and by analysis of sperm trajectories within an allurin gradient as observed by time-lapse microscopy. Chemotaxis was accompanied by an overall change in trajectory from circular to linear thereby increasing sperm movement along the gradient axis. Allurin did not increase sperm velocity although it did produce a modest increase in flagellar beat frequency. Oregon Green 488-conjugated allurin was observed to bind to the sub-equatorial region of the mouse sperm head and to the midpiece of the flagellum. These findings demonstrate that sperm have retained the ability to bind and respond to truncated Crisp proteins over 300 million years of vertebrate evolution.
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Affiliation(s)
- Lindsey A Burnett
- Molecular and Cellular Biology Graduate Program, School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA
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144
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Hoell C, Löwen H. Theory of microbe motion in a poisoned environment. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:042903. [PMID: 22181211 DOI: 10.1103/physreve.84.042903] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 09/01/2011] [Indexed: 05/31/2023]
Abstract
The motility of a microorganism which tries to avoid a poisoned environment by chemotaxis is studied within a simple model which couples its velocity to the concentration field of the poison. The latter is time independent but inhomogeneous in space. The presence of the poison is assumed to irreversibly reduce the propulsion speed. The model is solved analytically for different couplings of the total poison dose experienced by the microbe to the propulsion mechanism. In a stationary poison field resulting from a constant emission of a fixed point source, we find a power law for the distance traveled by the microbe as a function of time with a nonuniversal exponent which depends on the coupling in the model. With an inverted sign in the couplings, the acceleration of microbe motion induced by a food field can also be described.
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Affiliation(s)
- Christian Hoell
- Institut für Theoretische Physik II: Weiche Materie, Heinrich-Heine-Universität Universitätsstrasse 1, D-40225 Düsseldorf, Germany
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145
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Darszon A, Nishigaki T, Beltran C, Treviño CL. Calcium Channels in the Development, Maturation, and Function of Spermatozoa. Physiol Rev 2011; 91:1305-55. [DOI: 10.1152/physrev.00028.2010] [Citation(s) in RCA: 243] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A proper dialogue between spermatozoa and the egg is essential for conception of a new individual in sexually reproducing animals. Ca2+ is crucial in orchestrating this unique event leading to a new life. No wonder that nature has devised different Ca2+-permeable channels and located them at distinct sites in spermatozoa so that they can help fertilize the egg. New tools to study sperm ionic currents, and image intracellular Ca2+ with better spatial and temporal resolution even in swimming spermatozoa, are revealing how sperm ion channels participate in fertilization. This review critically examines the involvement of Ca2+ channels in multiple signaling processes needed for spermatozoa to mature, travel towards the egg, and fertilize it. Remarkably, these tiny specialized cells can express exclusive channels like CatSper for Ca2+ and SLO3 for K+, which are attractive targets for contraception and for the discovery of novel signaling complexes. Learning more about fertilization is a matter of capital importance; societies face growing pressure to counteract rising male infertility rates, provide safe male gamete-based contraceptives, and preserve biodiversity through improved captive breeding and assisted conception initiatives.
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Affiliation(s)
- Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Carmen Beltran
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Claudia L. Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
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146
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Espinal J, Aldana M, Guerrero A, Wood C, Darszon A, Martínez-Mekler G. Discrete dynamics model for the speract-activated Ca2+ signaling network relevant to sperm motility. PLoS One 2011; 6:e22619. [PMID: 21857937 PMCID: PMC3156703 DOI: 10.1371/journal.pone.0022619] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Accepted: 06/26/2011] [Indexed: 01/05/2023] Open
Abstract
Understanding how spermatozoa approach the egg is a central biological issue. Recently a considerable amount of experimental evidence has accumulated on the relation between oscillations in intracellular calcium ion concentration ([Ca]) in the sea urchin sperm flagellum, triggered by peptides secreted from the egg, and sperm motility. Determination of the structure and dynamics of the signaling pathway leading to these oscillations is a fundamental problem. However, a biochemically based formulation for the comprehension of the molecular mechanisms operating in the axoneme as a response to external stimulus is still lacking. Based on experiments on the S. purpuratus sea urchin spermatozoa, we propose a signaling network model where nodes are discrete variables corresponding to the pathway elements and the signal transmission takes place at discrete time intervals according to logical rules. The validity of this model is corroborated by reproducing previous empirically determined signaling features. Prompted by the model predictions we performed experiments which identified novel characteristics of the signaling pathway. We uncovered the role of a high voltage-activated channel as a regulator of the delay in the onset of fluctuations after activation of the signaling cascade. This delay time has recently been shown to be an important regulatory factor for sea urchin sperm reorientation. Another finding is the participation of a voltage-dependent calcium-activated channel in the determination of the period of the fluctuations. Furthermore, by analyzing the spread of network perturbations we find that it operates in a dynamically critical regime. Our work demonstrates that a coarse-grained approach to the dynamics of the signaling pathway is capable of revealing regulatory sperm navigation elements and provides insight, in terms of criticality, on the concurrence of the high robustness and adaptability that the reproduction processes are predicted to have developed throughout evolution.
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Affiliation(s)
- Jesús Espinal
- Instituto de Ciencias Fsicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Ciudad Universitaria, México, México
| | - Maximino Aldana
- Instituto de Ciencias Fsicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Ciudad Universitaria, México, México
| | - Adán Guerrero
- Departamento de Genética del Desarrollo y Fisiologa Molecular, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Christopher Wood
- Departamento de Genética del Desarrollo y Fisiologa Molecular, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiologa Molecular, Instituto de Biotecnologa, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Gustavo Martínez-Mekler
- Instituto de Ciencias Fsicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Ciudad Universitaria, México, México
- Centro Internacional de Ciencias, Cuernavaca, Morelos, México
- * E-mail:
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147
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Vacquier VD. Laboratory on sea urchin fertilization. Mol Reprod Dev 2011; 78:553-64. [PMID: 21805525 DOI: 10.1002/mrd.21360] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 06/27/2011] [Indexed: 12/16/2022]
Abstract
Since about 1880, the eggs and sperm of sea urchins have been used for the study of fertilization, the metabolic activation of development and gene regulatory mechanisms governing embryogenesis. Sea urchin gametes are a favorite material for observations of the process of fertilization in advanced high school, community college, and university biology laboratory courses. This article is a laboratory handout, designed for the student to follow in learning about fertilization. In addition to observations of sperm-egg interaction, simple experiments are described that demonstrate some mechanisms involved in the process. The hope is that by making simple observations of fertilization, the student will gain an appreciation for the fact that successive generations of higher organisms are bridged by the fusion of egg and sperm, two very different single cells.
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Affiliation(s)
- Victor D Vacquier
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, USA.
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148
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Sperm chemotaxis, fluid shear, and the evolution of sexual reproduction. Proc Natl Acad Sci U S A 2011; 108:13200-5. [PMID: 21788487 DOI: 10.1073/pnas.1018666108] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Chemical communication is fundamental to sexual reproduction, but how sperm search for and find an egg remains enigmatic. For red abalone (Haliotis rufescens), a large marine snail, the relationship between chemical signaling and fluid motion largely determines fertilization success. Egg-derived attractant plumes are dynamic, changing their size and shape in response to unique combinations of physical and chemical environmental features. Attractant plumes that promote sexual reproduction, however, are limited to a precise set of hydrodynamic conditions. Performance-maximizing shears are those that most closely match flows in native spawning habitats. Under conditions in which reproductive success is chronically limited by sperm availability, gametes are under selection for mechanisms that increase sperm-egg encounter. Here, chemoattraction is found to provide a cheap evolutionary alternative for enhancing egg target size without enlarging cytoplasmic and/or cell volume. Because egg signaling and sperm response may be tuned to meet specific fluid-dynamic constraints, shear could act as a critical selective pressure that drives gamete evolution and determines fitness.
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149
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Human sperm pattern of movement during chemotactic re-orientation towards a progesterone source. Asian J Androl 2011; 13:769-73. [PMID: 21765441 DOI: 10.1038/aja.2011.27] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Human spermatozoa may chemotactically find out the egg by following an increasing gradient of attractant molecules. Although human spermatozoa have been observed to show several of the physiological characteristics of chemotaxis, the chemotactic pattern of movement has not been easy to describe. However, it is apparent that chemotactic cells may be identified while returning to the attractant source. This study characterizes the pattern of movement of human spermatozoa during chemotactic re-orientation towards a progesterone source, which is a physiological attractant candidate. By means of videomicroscopy and image analysis, a chemotactic pattern of movement was identified as the spermatozoon returned towards the source of a chemotactic concentration of progesterone (10 pmol l⁻¹). First, as a continuation of its original path, the spermatozoon swims away from the progesterone source with linear movement and then turns back with a transitional movement that can be characterized by an increased velocity and decreased linearity. This sperm behaviour may help the spermatozoon to re-orient itself towards a progesterone source and may be used to identify the few cells that are undergoing chemotaxis at a given time.
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150
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Lockery SR. The computational worm: spatial orientation and its neuronal basis in C. elegans. Curr Opin Neurobiol 2011; 21:782-90. [PMID: 21764577 DOI: 10.1016/j.conb.2011.06.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Revised: 06/09/2011] [Accepted: 06/19/2011] [Indexed: 11/15/2022]
Abstract
Spatial orientation behaviors in animals are fundamental for survival but poorly understood at the neuronal level. The nematode Caenorhabditis elegans orients to a wide range of stimuli and has a numerically small and well-described nervous system making it advantageous for investigating the mechanisms of spatial orientation. Recent work by the C. elegans research community has identified essential computational elements of the neural circuits underlying two orientation strategies that operate in five different sensory modalities. Analysis of these circuits reveals novel motifs including simple circuits for computing temporal derivatives of sensory input and for integrating sensory input with behavioral state to generate adaptive behavior. These motifs constitute hypotheses concerning the identity and functionality of circuits controlling spatial orientation in higher organisms.
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Affiliation(s)
- Shawn R Lockery
- Institute of Neuroscience, 1254 University of Oregon, Eugene, OR 97403, USA.
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