DOCSLIB.ORG

Guidance Mechanisms in Bacteria and Sperm

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Guidance Mechanisms in Bacteria and Sperm Department of Biological Chemistry uidance mechanisms in Prof. Michael Eisenbach Rina Barak, Anat Bahat, Gbacteria and sperm Yaki Davidov, Leah Armon, Orna Liarzi, Peter Reuven, Gabriel Zarbiv Signal transduction in bacterial AcCoA serving as an acetyl donor, or chemotaxis by the enzyme acetyl-CoA synthetase We explore signal transduction (Acs), with acetate as the acetyl donor. strategies using chemotaxis of the In both cases the acetylation sites are bacteria Escherichia coli and Salmonella six lysine residues (Lys91, 92, 109, 119, 972 8 934 3923 typhimurium as a model. Bacterial 122 and 126), all located on the surface chemotaxis is a sophisticated system that binds to CheA, CheZ and FliM. FAX 972 8 947 2722 that integrates many different signals Mutational interference with either of [email protected] into a common output — a change in these processes results in defective www.weizmann.ac.il/~Eisenbach the direction of flagellar rotation. The chemotaxis. We even succeeded to signal transduction in E. coli chemotaxis detect CheY acetylation in vivo, finding is between two supramolecular that, on average, every molecule of complexes: the receptor supramolecular CheY is acetylated by autoacetylation. complex at the poles, and the flagellar- Our current studies are aimed at to fumarate and vice versa, mediates motor supramolecular complexes identifying the function of CheY fumarate to the switch. We established around the cell. The receptor acetylation in chemotaxis. that FRD forms a 1:1 complex with supramolecular complex includes One of the major questions in the switch-protein FliG, and that this the receptors and the enzymes that bacterial chemotaxis is how the interaction is required both for flagellar modulate the receptor activities as well switch of the bacterial flagellar motor assembly and switching the direction as the enzymes that are modulated functions. It is composed of multiple of flagellar rotation. We further by the receptors. The flagellar-motor copies of three proteins: FliM, FliG and showed that fumarate affects the supramolecular complex includes the FliN. Although some information on direction of flagellar rotation via FRD. motor and its gearbox, termed a switch. the structure of the switch proteins is This unexpected finding of functional A small protein, the excitatory response available, there is hardly any information interaction between an energy regulator CheY, shuttles back and about how the switch functions. Our conversion protein and the switch forth between the two supramolecular earlier studies identified fumarate as opens major intriguing questions, complexes and transduces sensory a switching factor, i.e., a molecule that currently addressed by us. In addition, information between them (Figure 1). enables the switch to shift from its using sophisticated single-cell imaging, Our research is focused on CheY and default state, counterclockwise, to the we study the behavior of the switch the switch. clockwise state. We used this finding as as a function of the intracellular level It is well established that the an end of a thread to investigate the of CheY. We also investigate the activity of CheY is regulated by switch function. Although our studies switching mechanism by quantitatively i its phosphorylation, the level of demonstrated that fumarate affects the studying events occurring at the switch, phosphorylation being determined switch, we could not detect its binding employing bioluminescence resonance by the histidine kinase, CheA, and to the switch complex or to individually energy transfer. the phosphatase, CheZ. We found isolated switch proteins (and to CheY, that CheY can also be activated by too). We, found, however, that the Sperm guidance in mammals acetylation. CheY acetylation can either membrane protein fumarate reductase Contrary to a prevalent belief, be carried out by autocatalysis, with (FRD), known to convert succinate there appears to be no competition in the mammalian female genital tract between large numbers of sperm cells racing towards the egg. Instead, small numbers of the ejaculated sperm cells enter the Fallopian tube and these few Weizmann Institute of ScienceWeizmann must be guided in order to make the ∙ remaining long, obstructed way to the egg. We revealed two active guidance (taxis) mechanisms: chemotaxis 2008 ∙ and thermotaxis. Both mechanisms are restricted to capacitated sperm cells, namely to cells that reached a maturation stage at which they can penetrate the egg and fertilize it. Fig. 1 Simplified scheme of signal transduction in bacterial chemotaxis of E. coli and S. Recently we found that both the egg typhimurium. Black arrows stand for regulated protein-protein interactions. CheY is a and its surrounding cumulus cells response regulator, CheA is a histidine kinase, and CheZ is a phosphatase. The scheme is secrete sperm chemoattractants, and not drawn to scale. Life Science Open Day determined that progesterone is the Mol. Cell. Biol. 7, 276-285.. Barak, R., Yan, J., Shainskaya, A. and Eisenbach, M. (2006) The chemotaxis response regulator CheY can catalyze its own acetylation. J. Mol. Biol. 359, 251-265. Eisenbach, M. (2007) A hitchhiker’s guide through advances and conceptual changes in chemotaxis. J. Cell. Physiol. 231, 574-580. Oren-Benaroya, R., Kipnis, J. and Eisenbach, M. (2007) Phagocytosis of human post-capacitated spermatozoa by macrophages. Hum. Reprod. 22, 2947-2955. Gakamsky, A, Schechtman, E., Caplan, S.R. and Eisenbach, M. (2008) Fig. 2 A scheme of the female genital tract demonstrating the location of sperm thermotaxis Analysis of chemotaxis when the and chemotaxis. fraction of responsive cells is small — application to mammalian sperm only chemoattractant secreted from isolated, intact switch complex of guidance. Int. J. Dev. Biol. In press. the cumulus cells. In addition we the bacterial flagellar motor: Lack found that a temperature difference of cooperativity. J. Biol. Chem. 278, Yan, J., Barak, R., Liarzi, O., is established at ovulation in the 25867-25871. Shainskaya, A. and Eisenbach, M. female’s oviduct as a consequence of Barak, R., Prasad, K., Shainskaya, (2008) In vivo acetylation of CheY, a temperature drop at its lower part A., Wolfe, A. J. and Eisenbach, M. a response regulator in chemotaxis (isthmus). Our pharmacological studies (2004) Acetylation of the chemotaxis of Escherichia coli. J. Mol. Biol. 376, 2+ 1260-1271. indicate that the IP3R Ca channel, response regulator CheY by acetyl- located on internal Ca2+ stores, CoA synthetase from Escherichia Cohen-Ben-Lulu, G.N., Francis, N.R., operates in human sperm thermotaxis coli. J. Mol. Biol. 342, 383-401. Shimoni, E., Noy, D., Davidov, Y., and that the response is mediated by Barak, R. and Eisenbach, M. (2004) Prassad, K., Sagi, Y., Cecchini, G., 2+ PLC and requires intracellular Ca . We Co-regulation of acetylation Johnstone, R.M. and Eisenbach, M. ii hypothesize that, in vivo, thermotaxis is and phosphorylation of CheY, a (2008) The bacterial flagellar switch a long-range mechanism, guiding sperm response regulator in chemotaxis of complex is getting more complex. cells in the Fallopian tube towards the Escherichia coli. J. Mol. Biol. 342, EMBO J. 27, 1134-1144. fertilization site, and chemotaxis is a 375-381. short-range mechanism that is mainly Eisenbach, M. (2004) Towards functional at close proximity to the understanding the molecular Acknowledgements egg (Figure 2). Our current efforts mechanism of sperm chemotaxis. J. are focused on identification of the M.E. is an incumbent of the Jack and Gen. Physiol. 124, 105-108. chemoattractant secreted by the egg Simon Djanogly Professorial Chair and on revealing the behavioral and Sun F., Bahat A., Gakamsky A., Girsh in Biochemistry. External support molecular mechanisms of mammalian E., Katz N., Giojalas L. C., Tur-Kaspa, from the Israel Science Foundation, sperm chemotaxis and thermotaxis. I. and Eisenbach, M. (2005) Human Binational Science Foundation, and sperm chemotaxis: Both the oocyte Minerva Foundation Institute of ScienceWeizmann and its surrounding cumulus cells ∙ Selected publications secrete sperm chemoattractants. INTERNAL support Bahat, A., Tur-Kaspa, I., Gakamsky, Hum. Reprod. 20, 761-767. Benoziyo Institute of Molecular 2008 A., Giojalas, L. C., Breitbart, H. and ∙ Bahat, A., Eisenbach, M. and Tur-Kaspa, Medicine and the Cohn Minerva Center Eisenbach, M. (2003) Thermotaxis of I. (2005) Periovulatory increase in for Biomembrane Research mammalian sperm cells: A potential temperature difference within the navigation mechanism in the female rabbit oviduct. Hum. Reprod. 20, genital tract. Nature Med. 9, 149-150. 2118-2121. Sagi, Y., Khan, S. and Eisenbach, M. Eisenbach, M. and Giojalas, L.C. (2006) (2003) Binding of the chemotaxis Sperm guidance in mammals — an response regulator CheY to the unpaved road to the egg. Nature Rev. Life Science Open Day.
Load more

Recommended publications
  • Structure-Based Redesigning of Pentoxifylline Analogs Against
    www.nature.com/scientificreports OPEN Structure‑based redesigning of pentoxifylline analogs against selective phosphodiesterases to modulate sperm functional competence for assisted reproductive technologies Mutyala Satish1,5, Sandhya Kumari2,5, Waghela Deeksha1, Suman Abhishek1, Kulhar Nitin1, Satish Kumar Adiga2, Padmaraj Hegde3, Jagadeesh Prasad Dasappa4, Guruprasad Kalthur2* & Eerappa Rajakumara1* Phosphodiesterase (PDE) inhibitors, such as pentoxifylline (PTX), are used as pharmacological agents to enhance sperm motility in assisted reproductive technology (ART), mainly to aid the selection of viable sperm in asthenozoospermic ejaculates and testicular spermatozoa, prior to intracytoplasmic sperm injection (ICSI). However, PTX is reported to induce premature acrosome reaction (AR) and, exert toxic efects on oocyte function and early embryo development. Additionally, in vitro binding studies as well as computational binding free energy (ΔGbind) suggest that PTX exhibits weak binding to sperm PDEs, indicating room for improvement. Aiming to reduce the adverse efects and to enhance the sperm motility, we designed and studied PTX analogues. Using structure‑guided in silico approach and by considering the physico‑chemical properties of the binding pocket of the PDEs, designed analogues of PTX. In silico assessments indicated that PTX analogues bind more tightly to PDEs and form stable complexes. Particularly, ex vivo evaluation of sperm treated with one of the PTX analogues (PTXm‑1), showed comparable benefcial efect at much lower concentration—slower
    [Show full text]
  • Bimodal Rheotactic Behavior Reflects Flagellar Beat Asymmetry in Human Sperm Cells
    Bimodal rheotactic behavior reflects flagellar beat asymmetry in human sperm cells Anton Bukatina,b,1, Igor Kukhtevichb,c,1, Norbert Stoopd,1, Jörn Dunkeld,2, and Vasily Kantslere aSt. Petersburg Academic University, St. Petersburg 194021, Russia; bInstitute for Analytical Instrumentation of the Russian Academy of Sciences, St. Petersburg 198095, Russia; cITMO University, St. Petersburg 197101, Russia; dDepartment of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139-4307; and eDepartment of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom Edited by Charles S. Peskin, New York University, New York, NY, and approved November 9, 2015 (received for review July 30, 2015) Rheotaxis, the directed response to fluid velocity gradients, has whether this effect is of mechanical (20) or hydrodynamic (21, been shown to facilitate stable upstream swimming of mamma- 22) origin. Experiments (23) show that the alga’s reorientation lian sperm cells along solid surfaces, suggesting a robust physical dynamics can lead to localization in shear flow (24, 25), with mechanism for long-distance navigation during fertilization. How- potentially profound implications in marine ecology. In contrast ever, the dynamics by which a human sperm orients itself relative to taxis in multiflagellate organisms (2, 5, 18, 26, 27), the navi- to an ambient flow is poorly understood. Here, we combine micro- gation strategies of uniflagellate cells are less well understood. fluidic experiments with mathematical modeling and 3D flagellar beat For instance, it was discovered only recently that uniflagellate reconstruction to quantify the response of individual sperm cells in marine bacteria, such as Vibrio alginolyticus and Pseudoalteromonas time-varying flow fields. Single-cell tracking reveals two kinematically haloplanktis, use a buckling instability in their lone flagellum to distinct swimming states that entail opposite turning behaviors under change their swimming direction (28).
    [Show full text]
  • Mechanisms of the Sperm Guidance, an Essential Aid for Meeting the Oocyte
    430 Editorial Mechanisms of the sperm guidance, an essential aid for meeting the oocyte Raquel Lottero-Leconte*, Carlos Agustín Isidro Alonso*, Luciana Castellano, Silvina Perez Martinez Laboratory of Biology of Reproduction in Mammals, Center for Pharmacological and Botanical Studies (CEFYBO-CONICET), School of Medicine, University of Buenos Aires (UBA), Buenos Aires, Argentina *These authors contributed equally to this work. Correspondence to: Silvina Perez Martinez, Senior Investigator. Center for Pharmacological and Botanical Studies, University of Buenos Aires (UBA), School of Medicine, National Scientific and Technical Research Council-Argentina (CONICET), Paraguay 2155, 15th Floor, C1121ABG, Ciudad de Buenos Aires, Argentina. Email: [email protected]. Provenance: This is an invited Editorial commissioned by Section Editor Weijun Jiang (Nanjing Normal University, Department of Reproductive and Genetics, Institute of Laboratory Medicine, Jinling Hospital, Nanjing University School of Medicine, Nanjing, China). Comment on: De Toni L, Garolla A, Menegazzo M, et al. Heat Sensing Receptor TRPV1 Is a Mediator of Thermotaxis in Human Spermatozoa. PLoS One 2016;11:e0167622. Submitted Mar 07, 2017. Accepted for publication Mar 14, 2017. doi: 10.21037/tcr.2017.03.68 View this article at: http://dx.doi.org/10.21037/tcr.2017.03.68 In mammals, ejaculated spermatozoa must migrate into the to a temperature gradient (towards the warmer temperature) female reproductive tract in order to reach and fertilize the (Figure 1). Spermatozoa can sense both the absolute ambient oocyte (Figure 1). The number of spermatozoa that reach temperature and the temperature gradient. Previous studies the oviductal isthmus (where they attach to oviductal cells showed that, at peri-ovulation stage, there is a temperature and form the sperm reservoir) is small (1,2) and only ~10% difference between the sperm reservoir site (cooler) and the of these spermatozoa in humans become capacitated (3) fertilization site (warmer).
    [Show full text]
  • SPERM THERMOTAXIS Anat Bahatand Michael Eisenbach
    SPERM THERMOTAXIS Anat Bahat and Michael Eisenbach∗ Department of Biological Chemistry, The Weizmann Institute of Science, 76100 Rehovot, Israel Abstract Thermotaxis — movement directed by a temperature gradient — is a prevalent process, found from bacteria to human cells. In the case of mammalian sperm, thermotaxis appears to be an essential mechanism guiding spermatozoa, released from the cooler reservoir site, towards the warmer fertilization site. Only capacitated spermatozoa are thermotactically responsive. Thermotaxis appears to be a long-range guidance mechanism, additional to chemotaxis, which seems to be short-range and likely occurs at close proximity to the oocyte and within the cumulus mass. Both mechanisms probably have a similar function — to guide capacitated, ready-to- fertilize spermatozoa towards the oocyte. The temperature difference between the site of the sperm reservoir and the fertilization site is generated at ovulation by a temperature drop at the former. The molecular mechanism of sperm thermotaxis waits to be revealed. Keywords: Thermotaxis (sperm); Guidance (sperm); Thermosensing (sperm); Fertilization; Spermatozoa (mammalian); Female genital tract. ∗ Corresponding author. Tel: +972-8-934-3923; fax: +972-8-947-2722. E-mail address: [email protected] (M. Eisenbach). 1. Introduction A new life begins after the sperm cell (spermatozoon) meets the oocyte and initiates a series of processes that leads to sperm penetration, sperm-oocyte fusion, and zygote division. However, the chance of an incidental encounter between the gametes is very slim (Eisenbach and Tur-Kaspa, 1999; Hunter, 1993) due to a number of reasons. First, the number of ejaculated spermatozoa that reach the oviductal isthmus [where they become trapped and form a sperm reservoir (Suarez, 2002)] is small (Harper, 1982).
    [Show full text]
  • Sperm Selection by Thermotaxis Improves ICSI Outcome in Mice
    www.nature.com/scientificreports OPEN Sperm selection by thermotaxis improves ICSI outcome in mice Serafín Pérez-Cerezales1, Ricardo Laguna-Barraza1, Alejandro Chacón de Castro1, María Jesús Sánchez-Calabuig1, Esther Cano-Oliva2, Francisco Javier de Castro-Pita2, 2 1 1 1 Received: 3 October 2017 Luis Montoro-Buils , Eva Pericuesta , Raúl Fernández-González & Alfonso Gutiérrez-Adán Accepted: 29 January 2018 The ejaculate is a heterogeneous pool of spermatozoa containing only a small physiologically adequate Published: xx xx xxxx subpopulation for fertilization. As there is no method to isolate this subpopulation, its specifc characteristics are unknown. This is one of the main reasons why we lack efective tools to identify male infertility and for the low efciency of assisted reproductive technologies. The aim of this study was to improve ICSI outcome by sperm selection through thermotaxis. Here we show that a specifc subpopulation of mouse and human spermatozoa can be selected in vitro by thermotaxis and that this subpopulation is the one that enters the fallopian tube in mice. Further, we confrm that these selected spermatozoa in mice and humans show a much higher DNA integrity and lower chromatin compaction than unselected sperm, and in mice, they give rise to more and better embryos through intracytoplasmic sperm injection, doubling the number of successful pregnancies. Collectively, our results indicate that a high quality sperm subpopulation is selected in vitro by thermotaxis and that this subpopulation is also selected in vivo within the fallopian tube possibly by thermotaxis. Before reaching the fertilization site, mammalian spermatozoa need to overcome a series of hurdles in the female genital tract1,2.
    [Show full text]
  • In Vitro Maturation of Cumulus–Oocyte Complexes and In
    animals Article In Vitro Maturation of Cumulus–Oocyte Complexes and In Vitro Sperm Capacitation Significantly Increase the Expression and Enhance the Location of the CXCL12 and CXCR4 Anchoring Attractant Complex in Pigs Cristina A. Martinez 1,* , Manuel Alvarez-Rodriguez 1 , Maite Casado-Bedmar 2 and Heriberto Rodriguez-Martinez 1 1 Department of Biomedical & Clinical Sciences (BKV), BKH/Obstetrics & Gynaecology, Faculty of Medicine and Health Sciences, Linköping University, SE-58185 Linköping, Sweden; [email protected] (M.A.-R.); [email protected] (H.R.-M.) 2 Department of Biomedical & Clinical Sciences (BKV), KOO/Surgery, Orthopedics and Oncology, Faculty of Medicine and Health Sciences, Linköping University, SE-58185 Linköping, Sweden; [email protected] * Correspondence: [email protected] Simple Summary: The process of mammalian fertilization is dependent on many mechanisms mediated by regulatory genes and proteins expressed in the gametes and/or the female genital tract. This study aimed to determine the expression and location of the cytokine complex CXCL12:CXCR4 in the porcine gametes: oocytes and spermatozoa. This complex is known to play a pivotal role for sperm attraction towards the oocyte prior to internal fertilization in several mammalian species. Gene Citation: Martinez, C.A.; and protein expressions were analyzed in female and male porcine gametes. The results showed Alvarez-Rodriguez, M.; Casado-Bedmar, M.; Rodriguez- that the CXCL12 gene expression was higher in mature cumulus cells, and CXCR4 was higher in Martinez, H. In Vitro Maturation of capacitated spermatozoa, both being requisites for gametes to accomplish fertilization. Moreover, Cumulus–Oocyte Complexes and In for the first time, the CXCL12 protein was located in the cytoplasm of cumulus cells from mature Vitro Sperm Capacitation COCs, and the CXCR4 protein was expressed in the midpiece and principal piece of uncapacitated Significantly Increase the Expression spermatozoa and also in the sperm head of capacitated spermatozoa.
    [Show full text]
  • Sperm Chemotaxis Is Driven by the Slope of the Chemoattractant
    bioRxiv preprint doi: https://doi.org/10.1101/148650; this version posted June 10, 2017. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY 4.0 International license . 1 Sperm chemotaxis is driven by the slope of the chemoattractant 2 concentration field 3 Ramírez-Gómez H.V.1, Jiménez-Sabinina V.2, Tuval I.3, Velázquez-Pérez M.1, Beltrán 4 C.1, Carneiro J.4, Wood C.D.1, 5, Darszon A.1, *, Guerrero A.1, 5, *. 5 1 Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de 6 Biotecnología, Universidad Nacional Autónoma de México (UNAM), Cuernavaca, 7 Morelos, 62210, México. 8 2 Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), 9 Heidelberg, Germany. 10 3 Mediterranean Institute for Advanced Studies, IMEDEA (CSIC-UIB), Esporles, 11 Balearic Islands, Spain. 12 4 Instituto Gulbenkian de Ciência (IGC), Rua da Quinta Grande, 6 2780-156, Oeiras, 13 Portugal. 14 5 Laboratorio Nacional de Microscopía Avanzada, Instituto de Biotecnología, 15 Universidad Nacional Autónoma de México (UNAM), Cuernavaca, Morelos, 62210, 16 México. 17 * Correspondence and requests for materials should be addressed to A.G. or A.D. 18 (email: [email protected], [email protected]). 1 bioRxiv preprint doi: https://doi.org/10.1101/148650; this version posted June 10, 2017. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.
    [Show full text]
  • Sperm Chemotaxis Is Driven by the Slope of the Chemoattractant
    RESEARCH ARTICLE Sperm chemotaxis is driven by the slope of the chemoattractant concentration field He´ ctor Vicente Ramı´rez-Go´ mez1, Vilma Jimenez Sabinina2, Martı´nVela´ zquez Pe´ rez1, Carmen Beltran1, Jorge Carneiro3, Christopher D Wood4, Idan Tuval5,6, Alberto Darszon1*, Ada´ n Guerrero4* 1Departamento de Gene´tica del Desarrollo y Fisiologı´a Molecular, Instituto de Biotecnologı´a, Universidad Nacional Auto´noma de Me´xico (UNAM), Cuernavaca, Mexico; 2Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany; 3Instituto Gulbenkian de Cieˆncia (IGC), Rua da Quinta Grande, Oeiras, Portugal; 4Laboratorio Nacional de Microscopı´a Avanzada, Instituto de Biotecnologı´a, Universidad Nacional Auto´noma de Me´xico (UNAM), Cuernavaca, Mexico; 5Mediterranean Institute for Advanced Studies, IMEDEA (CSIC-UIB), Esporles, Spain; 6Department of Physics, University of the Balearic Islands, Palma, Spain Abstract Spermatozoa of marine invertebrates are attracted to their conspecific female gamete by diffusive molecules, called chemoattractants, released from the egg investments in a process known as chemotaxis. The information from the egg chemoattractant concentration field is 2+ 2+ decoded into intracellular Ca concentration ([Ca ]i) changes that regulate the internal motors that shape the flagellum as it beats. By studying sea urchin species-specific differences in sperm chemoattractant-receptor characteristics we show that receptor density constrains the steepness of the chemoattractant concentration gradient detectable by spermatozoa. Through analyzing *For correspondence: different chemoattractant gradient forms, we demonstrate for the first time that [email protected] (AD); Strongylocentrotus purpuratus sperm are chemotactic and this response is consistent with [email protected] (AG) frequency entrainment of two coupled physiological oscillators: i) the stimulus function and ii) the 2+ Competing interests: The [Ca ]i changes.
    [Show full text]
  • The Micropyle: a Sperm Guidance System in Teleost Fertilization
    Development 109, 495-500 (1990) 495 Printed in Great Britain ©The Company of Biologists Limited 1990 The micropyle: a sperm guidance system in teleost fertilization DIALA AMANZE* and ARATIIYENGAR Department of Biology, University of Southampton, Medical and Biological Sciences Building, Bassett Crescent East, Southampton, SO9 3TU, UK * Present address for all correspondence: Division of Oral Biology, Institute of Dental Surgery, Eastman Dental Hospital, 256, Gray's Inn Road, London, WC1X 8LD, UK Summary The micropylar region of the Rosy barb, Barbus concho- guidance role of the micropylar region was calculated to nius, egg consists of 7-10 grooves and ridges, which enhance chances of egg penetration/fertilization by as drain directly into a funnel-shaped vestibule, the only much as 99.7 % once sperm were within the micropylar point on the chorion through which sperm-egg contact region, possibly in response to some form of chemo- is achieved during fertilization. Results of time-lapse attractant(s) from the egg. Sperm agglutination post- video microscope study and computer-aided analysis of fertilization was also found to occur preferentially along sperm motility pattern in the micropylar region snowed the grooves. Results of our in vitro fertilization exper- that the fertilizing sperm, usually the first to enter the iments showed association between point of sperm entry micropylar region, always travelled preferentially along and blastodisc formation: the blastodisc formed directly the grooves into the micropylar pit. Subsequently, 86 % beneath the micropyle in all undisturbed eggs. of sperm arriving the micropylar region within 30 s travelled preferentially along the grooves into the im- Key words: micropyle, sperm guidance, fertilization, mediate vicinity of the micropylar pit.
    [Show full text]
  • The Role of Taste Receptor Mtas1r3 in Chemical Communication of Gametes
    International Journal of Molecular Sciences Article The Role of Taste Receptor mTAS1R3 in Chemical Communication of Gametes Michaela Frolikova 1, Tereza Otcenaskova 1,2, Eliska Valasková 1, Pavla Postlerova 1,3, Romana Stopkova 2, Pavel Stopka 2 and Katerina Komrskova 1,2,* 1 Laboratory of Reproductive Biology, Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Prumyslova 595, 252 50 Vestec, Czech Republic; [email protected] (M.F.); [email protected] (T.O.); [email protected] (E.V.); [email protected] (P.P.) 2 Department of Zoology, Faculty of Science, Charles University, BIOCEV, Vinicna 7, 128 44 Prague 2, Czech Republic; [email protected] (R.S.); [email protected] (P.S.) 3 Department of Veterinary Sciences, Faculty of Agrobiology, Food and Natural Resources, University of Life Sciences Prague, Kamycka 129, 165 00 Prague 6, Czech Republic * Correspondence: [email protected]; Tel.: +420-325-873-799 Received: 27 February 2020; Accepted: 9 April 2020; Published: 10 April 2020 Abstract: Fertilization is a multiple step process leading to the fusion of female and male gametes and the formation of a zygote. Besides direct gamete membrane interaction via binding receptors localized on both oocyte and sperm surface, fertilization also involves gamete communication via chemical molecules triggering various signaling pathways. This work focuses on a mouse taste receptor, mTAS1R3, encoded by the Tas1r3 gene, as a potential receptor mediating chemical communication between gametes using the C57BL/6J lab mouse strain. In order to specify the role of mTAS1R3, we aimed to characterize its precise localization in testis and sperm using super resolution microscopy.
    [Show full text]
  • Guidance Mechanisms in Bacteria and Sperm
    Guidance mechanisms in bacteria and sperm Michael Eisenbach Signal transduction in bacterial chemotaxis We explore signal transduction strategies using chemotaxis of the bacteria Escherichia Rina Barak coli and Salmonella typhimurium as a model. Bacterial chemotaxis is a sophisticated system that integrates many different signals into a common output — a change in the Rony Oren-Benaroya direction of flagellar rotation. The signal transduction in E. coli chemotaxis is between two supramolecular complexes: the receptor supramolecular complex at the poles, and the flagellar-motor supramolecular complex around the cell. The receptor supramolecular Anat Bahat complex includes the receptors and the enzymes that modulate the receptor activities as well as the enzymes that are modulated by the receptors. The flagellar-motor Galit Cohen-Ben-Lulu supramolecular complex includes the motor and its gearbox, termed a switch. A small protein, the excitatory response regulator CheY, shuttles back and forth between the two supramolecular complexes and transduces sensory information between them (Figure 1). Anna Gakamsky Our research is focused on CheY and the switch. Orna Liarzi CheY can rapidly be activated by phosphorylation and, slower, by acetylation. The outcome of either of these activation modes is an upward shift in the probability of the flagellar motor to rotate in clockwise direction. CheY is phosphorylated by the histidine Peter Rohac kinase, CheA, and dephosphorylated by the phosphatase, CheZ. The phosphorylation of CheY affects the direction of flagellar rotation by increasing the affinity of the protein to its target at the flagellar switch — the switch protein FliM. CheY is acetylated and deacetylated, depending on the conditions, by the enzyme acetyl-CoA synthetase (Acs).
    [Show full text]
  • The Biological Mechanisms Regulating Sperm Selection by the Ovine Cervix
    158 REPRODUCTIONREVIEW The biological mechanisms regulating sperm selection by the ovine cervix S Fair1, K G Meade2, K Reynaud3, X Druart3 and S P de Graaf4 1Laboratory of Animal Reproduction, School of Natural Sciences, Faculty of Science and Engineering, University of Limerick, Limerick, Ireland, 2Animal & Bioscience Research Department, Animal & Grassland Research and Innovation Centre, Teagasc, Grange, Co Meath, Ireland, 3UMR PRC, INRA 85, CNRS 7247, Université de Tours, IFCE, Physiologie de la Reproduction et des Comportements, Institut National de la Recherche Agronomique, Nouzilly, France and 4The University of Sydney, School of Life and Environmental Sciences, Faculty of Science, Sydney, New South Wales, Australia Abstract In species where semen is deposited in the vagina, the cervix has the unique function of facilitating progress of spermatozoa towards the site of fertilisation while also preventing the ascending influx of pathogens from the vagina. For the majority of species, advances in assisted reproduction techniques facilitate the bypassing of the cervix and therefore its effect on the transit of processed spermatozoa has been largely overlooked. The exception is in sheep, as it is currently not possible to traverse the ovine cervix with an inseminating catheter due to its complex anatomy, and semen must be deposited at the external cervical os. This results in unacceptably low pregnancy rates when frozen-thawed or liquid stored (>24 h) semen is inseminated. The objective of this review is to discuss the biological mechanisms which regulate cervical sperm selection. We assess the effects of endogenous and exogenous hormones on cervical mucus composition and discuss how increased mucus production and flow during oestrus stimulates sperm rheotaxis along the crypts and folds of the cervix.
    [Show full text]