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Durham E-Theses Durham E-Theses Adaptive responses to temperature and photoperiod in neuromuscular transmissionin carcinus maenas (l) Qari, Suhaila How to cite: Qari, Suhaila (2004) Adaptive responses to temperature and photoperiod in neuromuscular transmissionin carcinus maenas (l), Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/3024/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk 2 ADAPTIVE RESPONSES TO TEMPERATURE AND PHOTOPERIOD IN NEUROMUSCULAR TRANSMISSION IN CARCINUS MAENAS (L). By Suhaila Qari A copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. Being a Thesis presented in candidature for a Degree of Doctor in Philosophy University Of Durham Department of Biological Sciences 2004 2 0 A. ~ 2005 j I rY DO(..~-; Druz DECLARATION I hereby declare that the work presented in this document is based on research wholly carried out by me, and that this document has not been presented anywhere else in any format for a degree. Suhaila Qari. 11 STATEMENT OF COPYRIGHT The copyright of this thesis rests with the author. No quotation from it should be published without the authors prior written consent. Any information derived from this thesis should be acknowledged. lll ACKNOWLEDGEMENTS I would like to give my warmest thanks to the following people who have supported me in different ways through the research and writing up periods of this thesis: Ill Dr. David Hyde who was my supervisor and guide, advised me not only on the writing of this thesis but was also an immeasurable help and support through the time I spent in Durham University. • Professor Ken Bowler for supervision and help with part of my project and also on the writing of this part. • Dr. Richard Hopkin for his interest and help with support me during 3 years at Durham University. He was a post doctoral researcher and introduced me to many experimental techniques and data processing methods and advised me in different ways. s Dr. Mirella Cuculescu, from the University ofNorthumbria, who guided me during 3months that I spent with her at the Northumbria University. I also extend my thanks. m Leena who gave me a back up and support with computer skills. • Many other colleagues from the Department who were always very prompt with all my requests of help. • On a personal basis I would like to express my thanks to my husband and my family who have been a continuous support through my study. Also to my parents who were a help with support during all my years of studying. iv ABSTRACT Neuromuscular synaptic transmission in the ectothermal crab Carcinus maenas was used to assess the extent to which photoperiod affected the attainment of temperature acclimation. A separate series of experiments were carried out to determine thermotolerance to high temperature (CTMax) and its dependence on prior heat shock and heat shock proteins. Dactylopodite closer muscle resting potentials and the characteristics of evoked excitatory junction potentials in response to stimulation of the excitatory tonic axon were recorded with intracellular microelectrodes and the extent of acclimation to temperature under different photoperiodic regimes was measured. Animals were acclimated for at least two week to either 8°C or 25°C with short day (8hr: 16hr, LID) or long day (16hr: 8hr, LID) photoperiods. Photoperiod differences had a marked effect on acclimation to temperature as measured by muscle resting potential and excitatory junction potential amplitude and facilitation. In short day photoperiods there was an acclimatory shift of muscle resting potential in crabs acclimated to 25°C compared with those acclimated to 8°C. Such an acclimatory shift of muscle resting potential was not seen in animals from long day photoperiods. By contrast facilitation showed acclimatory changes to temperature in long day but not in short day photoperiods. Excitatory junction potential amplitudes were increased in cold acclimation; this increase was larger from long day acclimated groups compared with short day groups. Furthermore photoperiod had a large effect on closer muscle tension in animals acclimated at low temperatures but little effect on animals acclimated at high temperatures. Heat shock reduced the amplitude of EJPs recorded in the closer muscle but enabled the EJP to be maintained for much higher temperatures. Heat shock also resulted in an increase in thermotolerance as measured by an elevation of CTMax from 33.04°C to 34.17°C. v TABLE OF CONTENTS Title Page ............................................................................................. .i Declaration ............................................................................................ ii Statement of Copyright ............................................................................ .iii Acknowledgements ................................................................................. iv Abstract. ...............................................................................................v Table of Contents ...................................................................................vi Chapter One. General Introduction ............................................................. 1 Chapter Two. General Material And Methods ............................................. , ... 30 Chapter Three. Effect Of Temperature And Photoperiod On Neurophysiological Properties OfNeuromuscular Transmission In Carcinus maenas. Introduction .............................................................................. 39 Methods ..................................................................................44 Results ....................................................................................45 Discussion ............................................................................... 50 Chapter Four. Heat Shock: Changes Critical Thermal Maximum (CTMax) And The Response OfThe Neuromuscular System In Shore Crab Carcinus maenas. Introduction .............................................................................. 57 Methods .................................................................................. 67 Result. ....................................................................................69 Vl Discussion ................................................................................73 Chapter Five. Muscle Tension: Effects Of Temperature, Photoperiod And Heat Shock. Introduction ..............................................................................82 Methods .................................................................................. 85 Results .................................................................................... 86 Discussion ......................................................................................................... 88 Chapter Six. General Discussion ............................................................... 92 Bibliography ................................................................................................................... 94 Vll Chapter One General Introduction The external environment has many physical variables, the abiotic environment and the biotic environment such as animals and plants. Some of the major abiotic variables are temperature, water availability and salinity, air humidity, light intensity, photoperiod, ambient pressure, gaseous composition of air. Temperature is an important environmental parameter which limits the distribution of living organisms and is an important determinant of their activity, particularly significant for animals whose body temperature fluctuates with changes in environmental temperature (Prosser and Heath, 1991 ). Environmental temperature variation will have a profound effect on rate processes of their biochemistry and physiology, and will result in changes at different levels of organization from the molecular to the behavior of the whole organism (Hochachka and Somero, 1984; Somero 1997). Life activities occur within a range of -0 to +40°C; most animals live within much narrower limits. But the range of temperatures on earth is greater than the range within which life is possible, air temperatures range from -70°C in polar regions to +85°C in hot deserts. Whereas surface waters range from -1.82°C in Arctic and Antarctic waters to +30°C in tropical landlocked bodies of water (Prosser and Heath, 1991). Although regions of relative constancy are the deep oceans and polar seas where temperature is 2-4°C at all times (Prosser and Heath, 1991 ), animals living at depths greater than fifty meters may experience almost constant temperatures over an annual period (Nicol, 1964). Polar environments both terrestrial and aquatic are less varied and species diversity is less than in the
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