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Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted as partial fulfillment of the requirements for the Doctor of Philosophy in History." Bibliography: leaves 213-217.

The aim of this thesis has been to investigate the individual decision making abilities of schooling fish in order to understand the composition of fish schools. Do individuals choose particular school-mates, and if so, on what basis are these decisions made? The null hypothesis, that schools are composed of random assortments of individual fish, has been rejected. School membership and structure are profoundly affected by the cognitive abilities and partner choice decisions of fish. Field work carried out in Trinidad and Dorset, UK (on guppies, Poecilia reticulata, and European minnows, Phoxinus phoxinus, respectively) has demonstrated that familiarity does indeed influence choice of schooling partner. Individual guppies under laboratory conditions and in the wild recognise and prefer school-mates with whom they are familiar, and schools of minnows are composed of a significant proportion of individuals which are familiar to one another. Preference for familiar conspecifics develops gradually (over at least 12 days in the case of guppies) and observations of wild guppies shows that this schooling preference is mediated by group size. Tendency to school with familiar fish is strong when group size is small, but declines thereafter, no preference being made as group size increases beyond ~40 individual females. The effect of group size on these partner choice decisions suggests that individual recognition may be possible. Intriguingly, a gender difference in the partner choice decisions of guppy schools in the wild has also been identified. Females spend more time schooling with individuals from their natural schools than males. This has important evolutionary consequences in terms of population differentiation and speciation. It seems, therefore, that schools are by no means composed of a random assortment of individuals. Indeed school structure and membership are profoundly affected by the remarkable discriminatory abilities of individual fish.

An osmoregulatory role for angiotensin II was investigated in the euryhaline European eel Anguilla anguilla L., plaice (Pleuronectes platessa) and dab (Limanda limanda). 1. Ile5 - and val5 -AII increased blood pressure in all species. Ile5 -AII produced a greater effect than val5 - AII, at equal concentrations, in eels, however in plaice and dab, this trend was reversed. Papaverine reduced blood pressure, followed by recovery to control in all cases. 2. Both AII sequences increased drinking rates except ile5 -AII in dab. ile5 -AII again proved more potent than val5-AII in eels and val5 - was greater than ile5- AII in flatfish. Papaverine increased drinking in all species. Captopril had no effect on eel or dab drinking rates, but reduced those of plaice. 3. 1.0nM and 10.0nM AII increased ANP release from isolated eel myocytes, except from FW atria. At 1.0nM, ventricular release was greater than atrial, however at 10.0nM, AII ANP secretion was similar in both types of myocyte. In all cases ANP release was greater from SW than FW myocytes. 4. Tissue/plasma ratios revealed greatest binding in SW eel liver. Tissue receptor specific binding was also greatest in FW eel liver membranes, however in SW tissues gill was slightly greater than liver. A FW eel liver membrane radioreceptor assay was developed. Binding was optimal at 22°C, 25mM calcium, protein concentration of 700ug, 125I-AII concentration of 25pM and an incubation period of 60 minutes. 6. Initial FW eel liver binding studies indicated two receptor classes with Kd=1. 5x10-11M and 2.46x10-10. However subsequent studies reveal Kd =3.31x10-8M in FW liver and Kd=1.09x10-7M in SW liver preparations. 7. 125I-ile5 -AII produced greater binding than 125I-val5 -AII in eel liver preparations. 125I-val5 -AII produced greater binding in flatfish membranes. Investigations of 125I-ile5 -AII displacement from FW eel liver membranes revealed peptide potencies in the following order, sar-AII > ile5-AII > 5-8AII > ile5-AI > val5-AI > ile4-AIII > val4-AIII > bradykinin > 1-4AII.

This is a study of the structure and functions of the endocrine tissues in the head-kidney of the teleost fish, the homologous tissues to the mammalian adrenal cortex (=adrenocortical tissue) and adrenal medulla (=chromaffin tissue). The study is divided into three main sections: 1.The first section comprises a study of the general morphology, at the anatomical and histological level, of the different types of head-kidney which occur in teleost fish. The range of types is illustrated by studies on twenty-four species, some of which have been previously investigated, and including in particular sixteen marine species from the Red Sea coast of Saudi Arabia collected by the author. 2. The second section of this thesis comprises a detailed study of the morphology of the head-kidney of one particular species, Phoxinus phoxinus (Linnaeus), and a two year study of seasonal variations in the activity of its adrenocortical and chromaffin tissue. Samples of fish were collected from a population in the Walton Reservoir, Scotland, at monthly intervals. The activity of the adrenocortical tissue was assessed by measuring nuclear diameter of the adrenocortical cells, a criterion already widely used for this purpose. The activity of the chromaffin cells was similarly assessed, though the methodology is less well established in this case. The effects were compared of electro-fishing followed by anaesthesis and immersion in Bouin's fixative while still under electronarcosis. Both proved to be relatively stress-free methods. 3. The third section of this thesis comprises a study of the fine structure of the endocrine tissues of the head-kidney of Phoxinus phoxinus and Salmo qairdnerii. Electron micrographs were prepared using fish caught under stress-free conditions in the Walton Reservoir, and from aquarium-maintained fish. The adrenocortical cells in both species are characterised by having a great many conspicuous mitochondria with tubule-vesicular internal structure. The nucleus is circular in section, and centrally situated in the cell. There is an extensive smooth endoplasmic reticulum and numerous ribosomes, Microvilli occur on cell surfaces in contact with veins. There is a wide range in the structure of the adrenocortical cells of individual fish; mitochondria range from small, elongated structure, with dark matrix to large, circular structures in which the internal structures eventually breaks down. The cytoplasm as a whole tends to be pale in cells with small dense mitochondria, and dense in cells with large, paler mitochondria. Pale highly vacuolated cytoplasm is associated with cells in which the mitochondria are breaking down; the vacuoles are probably associated with cells in which the mitochondria are breaking down; the vacuoles are probably associated with the degenerating mitochondria, In Phoxinus maintained in aquaria for twenty-four hours before killing, the proportion of adrenocortical cells with small mitochondria with dark matrices, -. as compared to fish caught by stress-free methods and fixed immediately. In Salmo which had been maintained in aquaria for longer periods, the proportion oft- cells showing mitochondrial degeneration and cytoplasmic vacuolation is higher. It is concluded that small, dark matrix mitochondria are typical of early stages of adrenal activity; dense cytoplasm and an increased number of large, circular mitochondria are typical of maximum activity; and mitochondrial degeneration and vacuolation of the cytoplasm is typical of exhaustion. Chromaffin cells, not hitherto described in teleost fish, are of the type found in other vertebrates, with many chromaffin vesicles containing varying amounts of granular inclusion. Synaptic contacts occur commonly, apparently all of cholinergic type. In Salmo the chromaffin and adrenocortical cells lie separately, but in Phoxinus the adrenocortical cells form a sheath round the posterior cardinal veins and their main tributaries, and the chromaffin cells lie beyond them, against the haemopoietic tissue. These chromaffin cells communicate with the vein by elongated projections running amongst the adrenocortical cells.

CHAPTER 1. The organisation and anatomical design of fish myotomal muscles. The literature on the anatomy, physiology and biochemistry of fish muscle is reviewed. CHAPTER 2. The effect of thermal acclimation on the metabolism of the swimming musculature of flounder (Platichthys flesus L.) Chapter 3. The effect of epinephrine administration on phosphorylase activity of the slow and fast muscles of flounder (Platichthys flesus L.) The results suggest glycogenolysis in flounder due to increased formation of phosphorylase a resulting from epinephrine activation of membrane bound adenyl cyclase. Chapter 4. Effects of hypoxia acclimation on anaerobic metabolism in the plaice (Pleuronectes platessa L.) There were no detectable levels of alcohol dehydrogenase activities, matched by the absence of ethanol pathway utilization. This may contribute to the failure of plaice to survive anoxia exposure. Chapter 5. Effects of acclimation to periodic anoxia exposure on the utilization of the ethanol pathway in goldfish (Carassius auratus L.). Chapter 6. Effects of acclimation to periodic anoxia exposure on the ultrastructure of goldfish (Carassius auratus L.) . CHAPTER 7. General Discussion. This section contains a general discussion of the biochemical responses to thermal acclimation and hypoxia. These responses precede ultrastructural changes which are stimulated to partially offset the adverse effects to normal homoeostasis. It includes a critical survey of current techniques and suggestions for future research.

Previous electrophysiological research on the fish olfactory system is reviewed and the conclusion reached that present knowledge concerning, in particular, the fundamental physiology of neuronal connections within the olfactory bulb, was rudimentary and confused. Field potentials were evoked in the olfactory bulb of teleost fish by electrical stimulation of the olfactory tract and nerve. The potential wave recorded at the bulbar surface consists of four components, N1, N2, N3, AND P, all of which appear to be of post-synaptic origin when the nerve is stimulated, whence they are usually preceded by a triphasic potential thought to represent the compound action potential of olfactory nerve fibres. The N1 wave evoked by olfactory tract stimulated is not of synaptic origin. It probably represents the synchronous antidromic activation of secondary neurons. The waves analysed with respect to voltage and time related to the underlying histology. The results indicate that the extracellular current flow around bulbar neuronal elements is essentially similar to that already described for mammals and is probably generated by similar pathways. This is surprising in view of fundamental anatomical dissimilarities, particularly regarding the dendritic field of mitral cells. The field potentials proved to be useful in the identification of single units at the time of recording. The spontaneous and evoked activity of identified mitral and granule cells could often be inhibited by stimulation of either the nerve or tract. The evoked field potentials could usually be similarly inhibited. Evidence has been obtained that this inhibition is mediated GABA and that it may well take place via a recurrent pathway involving reciprocal dendrodendritic synapses as in the mammalian system. Evidence was also obtained that this inhibition may, in part, result from the activation of granule cells by andrenergic centrifugal fibres when the olfactory tract is stimulated. Natural chemical stimulation of the olfactory mucosa with amino acid solutions produced a complex pattern of responses. Each odorant normally produced a unique pattern of excitatory and inhibitory responses across all units. Chi-square values were calculated for stimulatory effectiveness between forty-five pairs of odours. L-serine and L-alanine consistently showed a high degree of similarity with several other odours. The converse was true for GABA and L-histidine, although this pair had a high chi-square value when mutually compared. Enantiomeric pairs of amino acids were often found to have opposite stimulatory effects on bulbar units. These results are discussed in relation to the possible properties and configurations of odorant receptor sites for amino acids in the fish olfactory mucosa.

ix, 128 leaves, : ill. Thesis (Ph.D.)--University of Oregon, 1973 Vita Bibliography: l. [122]-128