In this work the use of the central nervous system (CNS) of the aquatic snail Lymnaea stagnalis on planar multi-electrode arrays (MEAs) was developed and analysis methods for the data generated were created. A variety of different combinations of configurations of tissue from the Lymnaea CNS were explored to determine the signal characteristics that could be recorded by sixty channel MEAs. In particular, the suitability of the semi-intact system consisting of the lips, oesophagus, CNS, and associated nerve connectives was developed for use on the planar MEA. The recording target area of the dorsal surface of the buccal ganglia was selected as being the most promising for study and recordings of its component cells during fictive feeding behaviour stimulated by sucrose were made. The data produced by this type of experimentation is very high volume and so its analysis required the development of a custom set of software tools. The goal of this tool set is to find the signal from individual neurons in the data streams of the electrodes of a planar MEA, to estimate their position, and then to predict their causal connectivity. To produce such an analysis techniques for noise filtration, neural spike detection, and group detection of bursts of spikes were created to pre-process electrode data streams. The Kohonen self-organising map (SOM) algorithm was adapted for the purpose of separating detected spikes into data streams representing the spike output of individual cells found in the target system. A significant addition to SOM algorithm was developed by the concurrent use of triangulation methods based on current source density analysis to predict the position of individual cells based on their spike output on more than one electrode. The likely functional connectivity of individual neurons identified by the SOM technique were analysed through the use of a statistical causality method known as Granger causality/causal connectivity. This technique was used to produce a map of the likely connectivity between neural sources.

Cephalopods first appeared around 500 million years ago. Since then they have developed from the external shelled ammonites, belemnites and nautiloid's to the soft bodied organisms we find today. By becoming soft bodied, protection which would have been provided by the shell was lost and a different approach to predator avoidance was adopted. Modern day cephalopods such as octopus, squid and cuttlefish frequently use camouflage techniques to avoid detection. In addition to countershading, which is an often used camouflage technique by aquatic species, the presence of chromatophores allow a versatile and rapid response in relation to stimuli. Cuttlefish expression of these chromatic responses can be categorised into chromatic components. It is the intensity and combination of the expression which makes them an interesting organism to study, when looking at how the environment influences camouflage decisions. In this thesis, I present six experiments looking at how external environmental factors influence camouflage in Sepia officinalis. The first experimental chapter looks at how 3D objects and proximity play a role in not only camouflage, but behavioural responses. The first set of experiments discuss how factors such as contrast and size of an object may elicit different responses both behaviourally and chromatically. The proximity of the cuttlefish to the object was then investigated to determine if visual input was a possible cause for the differences. Size of the object, proximity and contrast produced a differing response to that of a cuttlefish on a uniform background. The two subsequent chapters look at differing light information and whether cuttlefish treat these differences similar to that of low contrast. Reaction to turbid and low light levels show similar responses in camouflage, suggesting that similar mechanisms are employed when there is reduced light and high scatter information. In respect to luminance versus reflectance, cuttlefish seem to be able to differentiate between a projected and reflected image where they appear to treat projected images like a lower contrast value. The last experimental chapter investigates motion camouflage in respect to predation. Prey and distance had a large effect on behaviour and how camouflage was expressed. Over greater distances behavioural variance reduced. Darkening of the head region and arm waving was also present over a greater distance. Camouflage varied in relation to background with a more uniform background producing reduced expression when moving. Stationary predation therefore elicits a different response than that of motion camouflage in cuttlefish.

Endogenous nitric oxide (NO) produced by the enzyme NO synthase (NOS) has an important role in a variety of physiological processes. However, NO becomes noxious to cells if produced in excess. Therefore, the production of NO is tightly regulated. A particularly exciting and novel aspect of the regulation of NO signalling is the possibility that the expression of NOS genes is controlled by unconventional mechanisms that depend on the presence of natural antisense transcripts (NATs). In this thesis I investigate the important properties of two distinct NOS-related NATs: Lym-antiNOS2 and Mm-antiNOS1. I show that Lym-antiNOS2 RNA is widely expressed in the CNS of the pond snail Lymnaea stagnalis. Furthermore, I demonstrate that the expression of Lym-antiNOS2 is differentially regulated by training leading to long-term memory formation. Moreover, my results indicate that Lym-antiNOS2 RNA is subjected to peripheral trafficking in neurons. As for Mm-antiNOS1, I find that its expression is restricted to embryonic brain tissue and is almost undetectable in the adult brain of Mus musculus.

The effects of ionising radiation (IR) present in aquatic environments have been observed principally in vertebrate species but the potential biological impacts for aquatic invertebrate species are less clear. It is important to determine the influence of IR as a pollutant causing DNA damage in invertebrates at the molecular level since this may serve as an early warning of future population level repercussions. In this study, the biological effects of the IR as an environemntal contaminant at the molecular level was investigated by studying the induction of DNA damage, measured as mRNA expression of DNA repair genes and comet damage, in experimentally- and environmentally-exposed mussels, M. edulis. The experimental exposure consisted of different IR doses (1, 2, 10 and 50 Gy) and sampling at different post-exposure time points (1hr, 4 and 7 days). The environmental exposure was investigated using mussels collected from a contaminated site (Ravenglass Estuary) and a reference site (Brighton Marina). Two new molecular biomarkers were developed and employed. The first involves Rad51, a key protein in resynthesis, catalyzing and transferring of strands between broken sequences and its homologues in double strand break (DSBs) damage. The second biomarker involved a cell cycle checkpoint protein, check point kinase 1 (Chk1). To explore the activation of Rad51 and Chk1 mRNA activity as a result of exposure to IR, Rad51 and Chk1 mRNA in M. edulis were partially isolated and characterized and a quantitative assay developed to measure their expression using real-time PCR. Experimental exposure of M. edulis to IR (1, 2, 10 and 50 Gy) resulted in a statistically significant increase in the levels of Rad51 transcripts. Chk1 mRNA expression levels, initially investigated in the experimental group, were altered following exposure to IR. In the samples collected from the environment, Rad51 mRNA expression levels were increased in Ravenglass M. edulis gonad samples compared with the reference samples from Brighton Marina. In contrast, Chk1 transcripts decreased in Ravenglass M. edulis gonad samples compared to Brighton samples. The observed effects, and the potential role of both Rad51 and Chk1 in the IR DNA damage response of mussels are discussed.