WWW.ABSTRACT.DISLIB.INFO
FREE ELECTRONIC LIBRARY - Abstracts, online materials
 
<< HOME
CONTACTS



Pages:     | 1 |   ...   | 19 | 20 ||

«Connectivity, Organization, and Network Coordination of the Drosophila Central Circadian Clock by Zepeng Yao A dissertation submitted in partial ...»

-- [ Page 21 ] --

Furthermore, I have found that the Drosophila clock neuron network features diverse modes of coupling between the various clock neuron classes. Lastly, I revealed that the Drosophila clock neuron network consists of multiple independent oscillators and requires network-wide coherence for robust circadian rhythms in activity and sleep. My thesis research greatly advances our understanding of how the circadian clock neuron network is wired, organized, and coordinated. Given that disruption of circadian rhythms is associated with increased risks of a large spectrum of diseases, including obesity, heart diseases, cancer, and mood disorders (Albrecht, 2012), my thesis research may help address the widespread adverse effects of circadian rhythm disorders. Here, I summarize the key findings and implications of my thesis research as follows.

6.1 A new approach to address functional neuronal connectivity in the Drosophila brain Chapter 2 describes a new experimental approach that my colleagues and I developed for analyzing functional neuronal connections in the Drosophila brain. In this approach, the mammalian ATP-gated cation channel P2X2 is genetically expressed in neurons of interest to render them excitable by ATP on demand, while genetically encoded fluorescent sensors are simultaneously expressed in putative postsynaptic neurons to monitor their response upon the excitation of P2X2-expressing neurons. This approach has proved powerful, versatile, yet technically facile, and is now being widely used in the field of Drosophila neurobiology (e.g., Haynes et al., 2015; Kallman et al., 2015).

6.2 Physiological connectivity within the Drosophila clock neuron network Using the experimental approach my colleagues and I developed for neuronal connectivity analysis, I have confirmed a long predicted peptidergic connection from the LNvs to the LNds mediated by PDF, and showed that it is a modulatory connection that results in cAMP increases without causing acute excitation in the LNds (Chapter 2). Furthermore, I show that within the LNv group, PDF secreted from the l-LNvs acts to specifically increase cAMP levels but not calcium levels in the s-LNvs (Fig. 6.1 and Chapter 2). Lastly, using ATP/P2X2-mediated excitation of the glutamatergic DN1ps in conjunction with whole-cell patch-clamp recording of the LNds and l-LNvs, I uncover inhibitory connections from the DN1ps to the LNds and to the lLNvs (Chapter 3). Together, I have begun to delineate the neuronal connections between important groups of clock neurons. An extension of this experimental approach will allow the characterization of functional connectivity between other groups of clock neurons, and between clock neurons and potential input and output pathways.

6.3 Electrophysiological characterization of the critical LNd clock neurons In Chapter 3, I have provided the first electrophysiological analysis of the critical LNd clock neurons, which are considered collectively as the evening oscillator of the clock neuron network (Grima et al., 2004; Stoleru et al., 2004). I found that the LNds fire spontaneous tonic and bursting patterns of action potentials, and that the LNd neuronal activity is modulated by multiple fast neurotransmitters. Specifically, the LNds are excited by acetylcholine via nicotinic acetylcholine receptors, and inhibited by GABA and glutamate via GABAA receptors and the glutamate-gated chloride channel GluClα, respectively. The LNds’ receptivity to multiple fast neurotransmitters is in striking similarity to that of the LNvs (McCarthy et al., 2011; Lelito and Shafer, 2012). Using genetic and behavioral approaches, I found that while GABAergic inhibition of the lateral clock neurons functions to promote sleep at night, glutamatergic inhibition of the same neurons functions to promote wakefulness during specific times of the day. These results advance our understanding of the neurophysiological properties of central clock neurons and reveal how the various clock neuron classes integrate distinct synaptic inputs to orchestrate circadian rhythms in sleep and activity.

6.4 Diverse modes of coupling between the various clock neuron groups In Chapter 4 and Chapter 5, using a genetic strategy to specifically speed-up or slowdown the LNv molecular clocks, I experimentally investigated if and how molecular clocks of the various clock neuron classes are coupled to the critical LNv clocks. I found that the molecular clocks of the 5th s-LNv and most of the LNds are not coupled to the LNvs, while the two pairs of sNPF-expressing LNds can only be delayed but not advanced by the LNvs. In contrast, the CRYexpressing DN1ps can be both delayed and advanced by the LNvs. These results reveal that the various classes of clock neurons do not display a uniform mode of coupling. Rather, they display unique and complex coupling relationships that vary from group to group. This may have important implications in the clock network plasticity in the face of changing environments.

6.5 The Drosophila clock neuron network consists of multiple oscillators and requires network-wide coherence for robust free-running rhythms Despite the fact that the clock neuron network features a diversity of cell types that are anatomically and neurochemically distinct, it has been long modeled as a hierarchical twooscillator network, in which the morning oscillator (the LNvs) functions as a master pacemaker in the absence of environmental cues. In Chapter 4, through the genetic speeding-up and slowing-down the LNv clocks to different extents, I find that the LNvs can set the pace of the clock network only when their intrinsic period differs less than ~2.5 hours from that of the rest of the network. In contrast to the widely accepted “Master Pacemaker” model, my results demonstrate that the clock network consists of multiple oscillatory units, each of which drives rhythms in activity. Furthermore, I find that each oscillatory unit is unified by its neuropeptide output, which might be a general organizing principle that might apply to the circadian clock neuron networks of other animals. Lastly in Chapter 5, by genetically altering the clock speed in different subsets of clock neurons, I show that coherent free-running activity rhythms require molecular clock synchrony at least in all of the lateral clock neurons as well as the DN1ps, which constitute a much larger proportion of the clock neuron network than previously thought. These findings provide insights into the organization and network coordination of the Drosophila circadian clock.





Figure 6.1.

The l-LNvs modulate cAMP levels in the s-LNvs.

(A) Averaged Epac1-camps inverse FRET plot (±SEM) of l-LNvs imaged in c929-Gal4/PdfLexA,LexAop-Epac1-camps;UAS-P2X2/+ brains, before, during and after 30s perfusion of 1mM ATP (indicated on the bottom plot in each column). ATP/P2X2 mediated excitation caused clear inverse FRET increases. (B) Averaged Epac1-camps inverse FRET plot (±SEM) of s-LNvs from the same brains as (A). Excitation of the c929 network produced inverse FRET increases in the s-LNvs. (C) Averaged Epac1-camps inverse FRET plot (±SEM) of l-LNvs imaged in a Pdfr mutant background using han5304;c929-GAL4/Pdf-LexA,LexAop-Epac1-camps;UAS-P2X2/+ brains. c929 network excitation caused clear inverse FRET increases in these neurons. (D) Averaged Epac1-camps plot (±SEM) of s-LNvs from the same brains as (C). Excitation of the c929 network failed to produce inverse FRET increases in the s-LNvs in the absence of PdfR function. (E) Averaged Epac1-camps inverse FRET plot (±SEM) of l-LNvs imaged in PdfLexA,LexAop-Epac1-camps/+;UAS-P2X2/+ brains. ATP failed to produce inverse FRET increases in the absence of the GAL4 driver. The scale bars in (E) also apply to (A) and (C). (F) Averaged Epac1-camps inverse FRET plot (±SEM) of s-LNvs from the same brains as (E). ATP caused no obvious inverse FRET increases. The scale bars in (F) also apply to (B) and (D). (G) Comparison of maximum Epac1-camps responses for the l-LNv data shown in (A), (C), and (E).

ATP (1mM) perfusion caused significant inverse FRET increases in both the experimental (“Exp” c929-GAL4/Pdf-LexA,LexAop-Epac1-camps;UAS-P2X2/+) and PdfR mutant (“-PDFR” han5304 ;c929-GAL4/Pdf- LexA,LexAop-Epac1-camps;UAS-P2X2/+) conditions, relative to the negative control lacking the GAL4 driver for P2X2 expression (“-P2X2” Pdf-LexA,LexAopEpac1-camps/+;UAS-P2X2/+). (H) Comparison of maximum Epac1-camps responses for the sLNv data shown in (B), (D), and (F). ATP (1mM) perfusion caused significant inverse FRET increases in experimental (Exp) flies relative to both PdfR mutant (-PDFR) and -P2X2 controls.

Genotypes were identical to those in (G). For (G) and (H), *** indicates P 0.001 and n.s.

indicates no significant difference (P ≥ 0.05), by Kruskal—Wallis one-way ANOVA and Dunn's multiple comparison test. The methods and materials used in this figure are the same as those described in Chapter 2.

6.6 References

Albrecht, U. (2012). Timing to Perfection: The Biology of Central and Peripheral Circadian Clocks. Neuron 74, 246–260.

Grima, B., Chélot, E., Xia, R., and Rouyer, F. (2004). Morning and evening peaks of activity rely on different clock neurons of the Drosophila brain. Nature 431, 869–873.

Haynes, P.R., Christmann, B.L., and Griffith, L.C. (2015). A single pair of neurons links sleep to memory consolidation in drosophila melanogaster. Elife 2015, 1–24.

Kallman, B.R., Kim, H., and Scott, K. (2015). Excitation and inhibition onto central courtship neurons biases Drosophila mate choice. Elife 4, e11188.

Lelito, K.R., and Shafer, O.T. (2012). Reciprocal cholinergic and GABAergic modulation of the small ventrolateral pacemaker neurons of Drosophila’s circadian clock neuron network. J.

Neurophysiol. 107, 2096–2108.

McCarthy, E. V, Wu, Y., Decarvalho, T., Brandt, C., Cao, G., and Nitabach, M.N. (2011).

Synchronized bilateral synaptic inputs to Drosophila melanogaster neuropeptidergic rest/arousal neurons. J. Neurosci. 31, 8181–8193.

Stoleru, D., Peng, Y., Agosto, J., and Rosbash, M. (2004). Coupled oscillators control morning

Pages:     | 1 |   ...   | 19 | 20 ||


Similar works:

«Characterisation of the E.coli and Pseudomonas aeruginosa TolA-TolB interaction Eoin Cassels Doctor of Philosophy University of York Department of Biology December 2012 Abstract Abstract The Tol-Pal complex of Gram-negative bacteria is a highly conserved family of interacting proteins that span the periplasm, from inner to outer membrane. Despite decades of work on this protein complex, only the structure of a small part of the Tol complex in E.coli (TolB, Pal, TolB-Pal complex, TolA domain 3)...»

«PROLIFERATION OF BIOLOGICAL WEAPONS INTO TERRORIST HANDS BY RICHARD DANZIG1 NUNN PRIZE FELLOW, CENTER FOR STRATEGIC AND INTERNATIONAL STUDIES Because of their relative ease of purchase and development, biological weapons have been called “the poor man’s nuclear bomb.” This paper examines the extent to which such weapons are likely to spread – in particular, to terrorist hands – and whether the United States and its allies effectively control their proliferation. It concludes that...»

«John Moran, 2015 entry to The Byra J. and William P. Wreden Prize for Collecting Books and Related Materials Natural and Cultural Heritage of the Forgotten Coast and Red Hills I still remember, with a mix of embarrassment and grief, an afternoon when I was maybe fifteen, eating mullet with my mother at a mom-and-pop restaurant in Panacea, a destitute fishing hamlet near our hometown of Tallahassee, and she suggested she buy me a book on display, Jack Rudloe’s The Living Dock. At the register,...»

«Evolution: Fossils, Genes, and Mousetraps (2006) Dr. Kenneth R. Miller 1. Preamble: Kenneth Miller. (00:10) It's a pleasure to be here a special pleasure to speak to so many members of the scientific community of the future, because that's exactly who you are and I hope you, you take that role seriously. I hope you enjoy that role as well. One never really knows how one is gonna be introduced, so I figured I would introduce myself a little bit. I am a cell biologist, I work as he said on the...»

«Modeling Protein Structure From Its Sequence Marc A. Marti-Renom, Bozidar Yerkovich and Andrej Sali Laboratories of Molecular Biophysics Pels Family Center for Biochemistry and Structural Biology The Rockefeller University, 1230 York Ave, New York, NY 10021, USA KEYWORDS: Comparative Modeling, MODELLER, ModWeb, ModBase, ModView Corresponding authors: Andrej Sali Marc A. Marti-Renom The Rockefeller University, The Rockefeller University, 1230 York Ave, New York, NY 10021, USA. 1230 York Ave, New...»

«NATIONAL ACADEMY OF SCIENCES OF UKRAINE THE A.O. KOVALEVSKY INSTITUTE OF BIOLOGY OF THE SOUTHERN SEAS NAS UKRAINE V.N. Eremeev, A.R. Boltachev, B.G. Aleksandrov, S.V. Alyomov, Yu.A. Zagorodnya, E.P. Karpova, L.A. Manzhos, V.V. Gubanov BIOLOGICAL DIVERSITY OF THE COASTAL ZONE OF THE CRIMEAN PENINSULA: PROBLEMS, PRESERVATION AND RESTORATION PATHWAYS Sevastopol UDK 574.9(262.5+262.54) V.N. Eremeev, A.R. Boltachev, B.G. Aleksandrov, S.V. Alyomov, Yu.A. Zagorodnya, E.P. Karpova, L.A. Manzhos, V.V....»

«MCP Papers in Press. Published on April 9, 2014 as Manuscript M113.036392 Title: Ischemia in tumors induces early and sustained phosphorylation changes in stress kinase pathways but does not affect global protein levels Philipp Mertinsa,1,2, Feng Yangb,1, Tao Liub,1, DR Mania,1, Vladislav A. Petyukb,1, Michael A. Gillettea,1, Karl R. Clausera, Jana W. Qiaoa, Marina A. Gritsenkob, Ronald J. Mooreb, Douglas A. Levinec, Reid Townsendd, Petra Erdmann-Gilmored, Jacqueline E. Sniderd, Sherri R....»

«Frederica de Laguna 1906–2004 A Biographical Memoir by William W. Fitzhugh ©2013 National Academy of Sciences. Any opinions expressed in this memoir are those of the author and do not necessarily reflect the views of the National Academy of Sciences.FREDERICA DE LAGUNA October 3, 1906–October 6, 2004 Elected to the NAS, 1975 Among the many legendary characters who made the anthropology of the Arctic and Northwest Coast their calling, Frederica de Laguna stands as a towering figure,...»

«Subterranean A peer-reviewed open-access journal Subterranean Biology 19: 31–39 (2016) Hymenoptera from caves of Bakony Mountains, Hungary 31 RESEARCH ARTICLE doi: 10.3897/subtbiol.19.10016 Biology Published by http://subtbiol.pensoft.net The International Society for Subterranean Biology Hymenoptera from caves of Bakony Mountains, Hungary – an overlooked taxon in hypogean research Zoltán Vas1, Csaba Kutasi2 1 Hungarian Natural History Museum, Department of Zoology, Hymenoptera Collection,...»

«Conference Program November 22-24, 2016 Kyoto, Japan ACEAT Annual Conference on Engineering and Applied Science LSBE International Conference on Life Science & Biological Engineering APSSC Asia-Pacific Social Science Conference ICEAP International Conference on Education and Psychology ACEAT Annual Conference on Engineering and Applied Science ISBN 978-986-90827-7-8 LSBE International Conference on Life Science & Biological Engineering ISBN 978-986-89298-1-4 APSSC Asia-Pacific Social Science...»

«Biology of the Prokaryotes The following is a series of essays on selected aspects of prokaryote biology. These essays are ongoing, and the references are periodically updated, so do not assume completion (not that such works can ever be complete). The following topics are covered: · Motility in Prokaryotes o Bacterial flagella o Gliding motility o Chemosensing · Movement of materials within bacteria and cell size · Magnetotactic bactertia Motility in Prokaryotes 1. Motility Mode 1 Bacterial...»

«A permanence theorem for local dynamical systems Alessandro Fondaa,∗, Paolo Gidonib a Dipartimento di Matematica e Geoscienze, Universit` di Trieste, a P.le Europa 1, I-34127 Trieste, Italy b SISSA International School for Advanced Studies, Via Bonomea 265, I-34136 Trieste, Italy Abstract We provide a necessary and sufficient condition for permanence related to a local dynamical system on a suitable topological space. We then present an illustrative application to a Lotka–Volterra...»





 
<<  HOME   |    CONTACTS
2017 www.abstract.dislib.info - Abstracts, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.