Excretion of radioiodide by Gasterosteus aculeatus has been shown to vary directly with increases in salinity and inversely with size of fish. Erroneous excretion values may be produced by an apparent laboratory diuresis which seems to vary with season and salinity. During the initial stages of sexual maturation in sea water temporary changes in excretion occur which result in an increased retention of radioiodide by the fish. These changes show a greater development at lower salinities. The demonstrated dependence of thyroid uptake upon available radioiodide make this parameter an unreliable estimate of thyroid activity. The conversion ratio, except for errors which occur under conditions where the rate of radioiodide excretion is not constant over the period of the measurements, seems to be a valid estimate of thyroid activity. Technical factors, such as the binding of inorganic radioiodide to precipitated protein, can also produce erroneous conversion ratio values. Differences in the protein binding of inorganic radioiodide suggest that changes in blood proteins occur during sexual maturation. Although a seasonal increase in thyroid activity occurs there is no correlation between this and the increase in radioiodide retention. There is therefore no reason to believe that the thyroid is responsible for the observed changes in retention of radioiodide. / Science, Faculty of / Zoology, Department of / Graduate

The role of prolactin in osmotic and ionic regulation of the marine threespine stickleback (Gasterosteus aculeatus L., form trachurus) in fresh water has been investigated in winter (or late autumn) and spring. Sticklebacks in late autumn or early winter, when transferred from sea water to fresh water, suffered a high mortality which could be reduced by prolactin treatment. The fish also displayed a greater fall in plasma osmolality and a smaller fall in urine osmolality than late-spring fish transferred to fresh water in the same way; this seasonal difference was apparently triggered by photoperiodic changes and could be eliminated by prolactin treatment of the late-autumn or early-winter fish. Similarly, a seasonal difference exists in the histological picture of the glomeruli of late-autumn and late-spring sticklebacks, and this difference could be eliminated by prolactin treatment of the former fish. The fall in plasma osmolality in late-autumn and winter fish after transfer to fresh water was paralleled by a rapid drop in plasma sodium and chloride, which could be corrected by a single injection of prolactin given 24 hr before the transfer. Plasma potassium, however, seemed unaffected by prolactin treatment. The evidence suggests that prolactin is essential for freshwater survival of sticklebacks and that prolactin undergoes seasonal changes in secretion associated with photoperiodic changes; the secretion is minimal in the autumn and winter when the fish live in sea water or brackish water, and maximal in the spring and summer when the fish migrate to (or are in) fresh water, to breed. Thus prolactin may be involved in the freshwater migration of sticklebacks. Next, the mechanism of action of prolactin was studied. Prolactin seems to exert its effects (in fresh water) on the three recognized organs of osmotic and ionic regulation in teleosts, viz. kidneys, gills and gut. In the kidneys, prolactin increased urine flow, apparently as a result of an increased GFR. Prolactin reduced the apparent increase in intracapsular space in the glomeruli of the late-autumn and winter sticklebacks, and, consequently, increased the percentage frequency of glomeruli with no evident intracapsular space. The data are interpreted to mean that prolactin rendered glomeruli more functional or more glomeruli fully functionaland, hence, increased GFR. Since the increase in urine flow and GFR was paralleled by a decrease in urine osmolality and urine concentrations of sodium and chloride, prolactin must also increase renal tubular reabsorption of sodium and chloride (A) and/or decrease water reabsorption (B); and since the total renal loss of sodium and chloride did not appear to be significantly increased despite an increase in GFR, A must occur with or without B. Prolactin, however, apparently increased the total renal loss of potassium and did not affect the tubular potassium reabsorption, although there was a suggestion that prolactin actually decreased tubular reabsorption of potassium. In the gills (or other regions around the head), prolactin reduced the net osmotic influx of water and the net loss of sodium, chloride and C¹⁴ (from injected C¹⁴ -inulin); the latter was probably because prolactin reduced the outflux. These changes were accompanied by the behaviour of the gill mucous cells, which were increased in density by prolactin treatment, suggesting a cause-or-effect relationship. In the gut, prolactin reduced water absorption and, at the same time, seemed to reduce the freshwater drinking rate. Thus, it appears that prolactin was able to reduce or prevent osmotic flooding of sticklebacks in fresh water by reducing extrarenal osmotic influx of water and increasing renal loss of water via an increase in GFR and urine flow, and also, possibly, by reducing drinking rate and water absorption by the gut; at the same time, prolactin reduced extrarenal loss of sodium and chloride but did not apparently affect renal loss of the ions, which was small compared to the extrarenal loss. By these mechanisms, prolactin maintained plasma osmolality and sodium and chloride levels after transfer of the fish to fresh water, and, consequently, was able to promote freshwater survival of the fish in the autumn and winter. / Science, Faculty of / Zoology, Department of / Graduate

Five populations of the threespine stickleback, Gasterosteous aculeatus,from the upper Cowichan River system (Vancouver Island, British Columbia) were surveyed to assess interpopulation levels of variability in trophic morphology. Phenotypic divergence is assumed to be a post-glacial event. Nine characters were scored; eight were related to feeding and the ninth character was lateral plate number. All populations surveyed were the low plate morph; however populations of Gasterosteus in lakes lacking piscivorous fish had significantly fewer lateral plates than populations in lakes with predatory fish species. Three trophic 'morphotypes' were identified, each associated with one of three lake environments. Populations inhabiting benthic dominated environments ('benthic morph') were found to possess reduced gill raker number and reduced gill raker length but increased upper jaw length relative to populations from lentic environments ('limnetic morph'). An intermediate morph may also exist and is characterized by a morphology suitable to either trophic regime. Analysis of stomach contents showed diet type (benthic or limnetic) to be significantly dependent on morph. The functional significance of differences in trophic morphology was investigated in three feeding experiments using a representative population from each morphotype. The longer jaw of the benthic and intermediate morphs allowed them to ingest a larger benthic prey than the limnetic. No behavioural component to benthic foraging success between populations was identified, although increased jaw length shortened the time spent manipulating prey. Both the intermediate and limnetic morphs were better foragers on an experimental limnetic prey than was the benthic. Head length, snout length, gill raker density and gill raker number were strongly correlated with limnetic foraging success. The quantitative genetics governing the eight trophic characters were investigated using the same three representative populations. Broad sense estimates of character heritabilities ranged from 0.132 to 0.677; all estimates were significant. Character genetic correlations were reasonably strong (0.3 ≤ |rG| ≤ 0.9), while character correlations arising through environment tended to be lower. Cluster analyses of the genetic correlation matrices defined two character suites, the first grouped measures of head shape, the second grouped measures of gill raker structure. The patterns of genetic correlations suggest the three populations are distinct races. Selection gradients for divergence between morphotype indicated that directional selection had operated hardest on head length, snout length, gill raker number, head depth and upper jaw length; hence selection has operated to modify characters related to food size. The benthic-limnetic and intermediate-limnetic morphs were separated by the greatest selection distance while the intermediate-benthic morphs were separated by the shortest selection distance. These results support the conclusion that directional selection, arising from trophic resource differences between lakes, has organized interpopulation variability for Gasterosteus within the upper Cowichan drainage. The racial distinction of each population coupled with the functional significance of some components of trophic morphology indicate that at least the benthic and limnetic morphs must be considered 'ecotypes'. / Science, Faculty of / Zoology, Department of / Graduate

Testis-specific protein (TSP) variability has been examined in the three-spined stickleback, Gasterosteus aculeatus and related species including Gasterosteus wheatlandi, Punqitius pungitius, and Aulorhynchus flavidus, in order to determine if such proteins can act as molecular markers for different species of Gasterosteiformes and for different populations of a single species. Cytochemistry of the sperm histones of Gasterosteus aculeatus revealed that these basic proteins can be classified as intermediate sperm histones according to Bloch's (1969 and 1976) categories. Electron microscopy indicates that the chromatin in the nucleus condenses in a granular pattern as the somatic histones of the spermatogonia are replaced by the sperm histones in the spermatid during spermiogenesis in this teleost. The testis specific proteins (TSP's) of G. aculeatus and related species were characterized by electrophoresis on polyacrylamide gels and by hydrolysis of the amidoblack stained bands from the gel and subsequent amino acid analysis. The compositional analysis revealed that all the TSP's of the fish in the order Gasterosteiformes were intermediate type containing histidine, lysine, and arginine amino acid residues. However, the TSP's of different species could be distinguished by their electrophoretic mobilities on polyacrylamide gels and by differences in the amino acid composition. Apparently TSP's can act as molecular markers to distinguish these particular teleosts. To establish the electrophoretic pattern for the TSP's of mature, breeding G. aculeatus, the developmental profile was investigated over the course of a season for a population of these fish in Jericho Pond, Vancouver, B.C. As the testis matures, somatic histones are replaced gradually by one or several rapidly moving TSP's. Some protein bands that are present in fish with immature testes are removed by the time the electrophoretic pattern typical for mature males occurs during the breeding season. This pattern shows only rapidly moving TSP's and very low levels of somatic histones. Experiments using alkaline phosphatase indicated that the electrophoretic profile of the multiplicity of TSP'.s of mature fish was not due to differences in charge because of phosphorylation of serine side chains in TSP bands. In addition to acting as molecular markers for different species, the TSP's showed an electrophoretic profile in anadromous G. aculeatus that differed from the profile in freshwater fish with respect to band morphology and also the number of bands seen on long gels. Here, too, the similarity of the freshwater and anadromous TSP profiles was reinforced by similar digestion patterns with cyanogen bromide, confirming the presence of methionine in these proteins. However, different populations of anadromous G. aculeatus either from British Columbia or from Quebec were indistinguishable by electrophoretic analysis. Moreover the electrophoretic and amino acid analysis could not distinguish between G. aculeatus from different freshwater populations. There was no discernable trend for the multiplicity of TSP's from such populations. However, in the fish from two freshwater lakes there was an indication that the benthic forms (bottom dwellers) might have reached sexual maturity later than the limnetic forms (top dwellers) as the limnetic animals lost their somatic histones before the benthics did. From these analyses, TSP's apparently can act as molecular markers between different species of Gasterosteiformes, and to a lesser extent between anadromous and freshwater forms of G. aculeatus. This agrees with the findings of Mann et. al. ( 1982) that the spermatid/sperm-specific proteins of the frog genus Xenopus can distinguish between different species of the genus and somewhat between different subspecies of Xenopus laevis. Both the Gasterosteiformes and anuran TSP's are of the intermediate type. In several instances, particular species of fish gave anomalous results. For example, an anadromous G. aculeatus showed the presence of a band typical for the TSP of G. wheatlandi on polyacrylamide gel electrophoresis. Perhaps this is due to hybridization between Gasterosteidae of different species. Finally, incubation of TSP preparations at 37 °C indicated the presence of endogenous protease at neutral pH. Such a protease was not active at acid pH and therefore did not interfere with the electrophoretic analysis. / Science, Faculty of / Zoology, Department of / Graduate

Threespine sticklebacks (Gasterosteus aculeatus) inhabit both marine and freshwater environments along the Pacific coast of North America, In this study, sticklebacks collected from 73 locations on Vancouver Island, the Sechelt Peninsula and the lower Fraser River Valley of British Columbia, and six sites in northwestern Washington State, were assayed by starch gel electrophoresis in order to examine relationships among and between marine (trachurus) and freshwater (leiurus) populations. Six enzymes, coded for by eight genetic loci, were examined. Of these, two aere monomorphic for the same allele in all populations, the remainder were polymorphic to varying degrees. Laboratory breeding studies employing both marine and freshwater fish as parents confirmed the genetic interpretation of observed variability in isozyme banding patterns. One of the monomorphic enzytaes, isocitrate dehydrogenase, exhibited a sexually dimorphic isozyme pattern. Levels of polymorphism and heterozygosity were slightly higher than average, bat within the range of those characterizing other vertebrate species. In general, genotypic ratios conformed to Hardy-Heinberg expectations, and allele frequencies within populations did not shift over short time periods. Gene frequencies did not vary among sticklebacks of different sizes nor among those caught by different methods from the same population. Gene frequencies at all polymorphic loci were significantly heterogeneous among stickleback populations. Average frequencies at two loci (Pgm and Mdh-3) differed significantly between marine and freshwater fish. In addition, average frequencies at two other loci (Mdh-1 and Ck) were different among sticklebacks inhabiting different types of freshwater environments. Among freshwater populations the Ck ⁸⁵ and Pgm ⁹⁰ alleles displayed clinal geographic variability in frequency, possibly as a result of the differential sampling of various freshwater habitat types in different regions. Allele frequencies at three loci (Pgm, Ck and Pgi-2) differed between marine sticklebacks collected from the Strait of Georgia and those from waters off the vest coast of Vancouver Island. Calculation of Nei’s genetic distance indicated that while marine populations are relatively homogeneous at electrophoretic loci, freshwater populations are highly heterogeneous. The average genetic distance between marine and freshwater populations was similar to that separating pairs of freshwater populations. The genetic distance between freshwater populations was greater between than within watersheds, but allele distributions at individual loci did not differ significantly between two watersheds levels of polymorphism and heterozygosity were relatively high in populations from the ocean, large lakes and low-lying streams, and low in those from small lakes and isolated streams. Both deterministic (natural selection) and stochastic (founder effects and genetic drift) mechanisms can be invoked to explain these patterns. Morphologically and ecologically distinct benthic and limnetic sticklebacks within single lakes, and freshwater and marine sticklebacks within a stream, constituted genetically discrete populations. There was a striking congruence in the patterns of morphological and electrophoretic variability among the populations comprising such 'species pairs'. The results of this study are compatible with the suggestion that freshwater populations of the study area are polyphyletic, and have arisen independently from marine sticklebacks which invaded the region since the last ice age, about 10,000 years ago. / Science, Faculty of / Zoology, Department of / Graduate

The three general body armour forms of Gasterosteus aculeatus (Linnaeus), high, intermediate and low plate count forms, are found in nonbreeding marine populations. In breeding season initially the population in the nontidal portion of Bonsall Creek consisted of the low and intermediate plate count forms. Later when the tidal zone was occupied by breeding sticklebacks all three body armour forms were present and from the limit of the tidal influence the low and intermediate forms became less frequent seaward. In Chase Creek there exists an anadromous breeding population but there was no adjoining freshwater population. In Chase Creek however there did exist a zone where all three body armour form were present. Therefore, the development of the pattern of plate variation in the creek's tidal zone does not appear to be dependent upon the presence of both freshwater and marine population tyrjes. In Bonsall Creek where both a freshwater and a marine population bred, low plate count individuals from the freshwater zone and high plate count individuals from the adjoining tidal zone were reciprocally transferred in wire baskets. Mortalities of transferred fish were shown to be significantly higher than those of the controls indicating a possible barrier to gene exchange between the two populations. However, the presence of the intermediate plate count form in the freshwater zone of Bonsall creek strongly implicates gene flow between these two groups of fishes. all three forms collected from the tidal zone of Chase Creek. Showed the same mortality rate when placed in freshwater. This suggests that the low and intermediate plate count fish breeding in the tidal portion of Chase Creek were of marine origin. Ten morphological characters were combined in a discriminant function and used to classify breeding individuals from Bonsall Creek. The discriminant function showed a gradual change in morphology of the fish distributed from marine to freshwater. It is concluded that while there was considerable differentiation between adjoining freshwater and anadromous breeding populations of Gasterosteus aculeatus, no evidence of a morphological discontinuity as would be expected of separate species. However, the presences of the hybrid form in the freshwater zone of Bonsall Creek strongly implicates gene flow between those freshwater and marine groups of fish. Eleven populations ranging geographically from the Alaska Peninsula to Chehalis Biver in Washington State were similarly subject to discriminant function analysis. These samples did not show clinal variation in their scores, though the scores of the populations were significantly different suggesting local adaptation and possible restriction of gene flow within the marine environment. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Wisconsin. / Includes bibliographical references (leaves 42-46).

The present study investigated aspects of the biology of the cestode, Proteocephalus filicollis from the three-spined stickleback Gasterosteus aculeatus from Airthrey Loch, Scotland. The population biology study demonstrated that the parasite has an annual cycle of recruitment, which occur mostly in late summer and early autumn. The cestode did not show preference for any sex of the host. Maturation of the cestode also showed a seasonal cycle with the majority of worms maturing in late spring and early summer, but this period may be extended in different generations. Proteocephalus filicollis was overdispersed throughout the year in all sizes of fish, moreover variance to mean ratio always exceeded unity. No severe pathology was observed due to attachment of the worm to the intestine of the fish. The worm population in different sections of the intestine varied according to season and maturity stage. The P. filicollis migrate from the rectum to the anterior intestine as they mature and it is suggested that growth and maturation of the worm is a major stimulus for this migration. Proteocephalus filicollis has a high fecundity as indicated by the higher number of eggs per mm of gravid portion of the strobila and high fertility. Infrapopulation size did not show any relationship with length of worm, percentage gravid portion, number of gravid segments or mean length of gravid segments. Numbers of eggs are correlated to length of the worm, but not to infrapopulation size. Numbers of eggs per mm of the gravid portion are not correlated to length of worm or infrapopulation size. Acanthocyclops robustus was used as an experimental intermediate host. 15-16°C was the optimum experimental temperature for growth and a fully developed larva was formed in 23-27 days at this temperature. No growth was observed at 4°C, growth was slow at 10°C, but rapid at 21-22°C. The eggs are infective for 25 days at 4°C, 10°C and 15-16°C, but for only 15 days at 21-22°C. Prevalence and mortality of copepods are significantly correlated to their exposure time to parasite eggs, but mean intensity of infection did not show any relationship to the exposure time to the eggs. Ultrastructural studies demonstrated that a mature egg is surrounded by at least four embryonic envelopes, the capsule, the outer envelope, the inner envelope, and the oncospheral membrane. All these envelopes originate differently and undergo definite changes during their development.

A population of three-spined stickleback, Gasterosteus aculeatus L., was sampled every two weeks for 14 months from Airthrey Loch on the campus of the University of Stirling. A total of 857 fish were collected and three species of parasites were studied. The monogenean Gyrodactylus gasterostei was found on the skin and fins and two myxosporean parasites, Sphaerospora elegans and Myxobilatus gasterostei, were present in the kidney. All parasite species were present throughout the year but abundance was correlated with the yearly life cycle of the host fish. Lower prevalence and intensity were observed in summer due to the large number of young fish in the samples. The comparative ultrastructure and development of the two myxosporeans was studied by light and transmission and scanning electron microscopy. Both myxosporeans followed the general pattern of myxosporean development but showed some novel features. Sphaerospora e/egans had two distinct developmental cycles. A proliferative cycle involving extrasporogonic stages occurred in the blood whereas spore production occurred in the kidney. Light microscopy of Giemsa stained blood smears suggested proliferation of extra-sporogonic stages by external budding or plasmotomy. Structural similarities between extra-sporogonic blood stages and sporogonic kidney stages are discussed. Although S. elegans mostly formed disporous plasmodia, monosporous plasmodia were also occasionally observed. Before the appearance of sporogonic cells within the early pseudoplasmodia, certain areas of pseudoplasmodial cytoplasm became electron lucent, eventually acquired cell organeUes and later appeared as sporogonic cells. Developing valvogenic cells contained protuberances at the posterolateral side of spores which disappeared in mature spores. Characteristic lipid bodies were seen in developing capsulogenic cells and developing uninucleated sporoplasmic cells contained abundant glycogen granules. The sporoplasmic cells were devoid of sporoplasmosomes. Plasmodia of M. gasterostei were mono, di or polysporous and showed features of both coelozoic and histozoic myxosporeans, including a unit surface membrane, simple pinocytosis aanand presence of a number of vegetative nuclei and generative cells, the latter which formed pansporoblasts before the initiation of sporogenesis. A membrane bound tubular structure and some electron dense fibrillar bundles are previously undiscovered cytoplasmic organelles of the plasmodia. Developing capsulogenic cells contained characteristic membrane bound vacuoles filled with electron dense (glycogen) material. Myxobilatus gasterostel attached to the epithelial cells by plasmodial surface projections and there were electron dense areas at the point of attachment. Sphaerospora elegans showed occasional hairlike processes projecting from the pseudoplasmodial surface to the microvillous brush border of the epithelial cells. There were no electron dense areas at the point of attachment to the epithelial cells of the kidney tubules. Early undifferentiated pre-sporogonic stages of both parasites were occasionally present intracellularly in the tubular epithelium suggesting this is a route of entry into the tubular lumen. Early stages of S. elegans were also seen in the capillary lumen of the glomerulus. Intracellular and intraluminal stages of S. elegans and M. gasterostel caused pathological changes in different ways. Histopathological changes associated with S. elegans included vacuolation and accumulation of electron dense material in the epithelium whereas M. gasterostei caused large vacuolation with necrosis of the epithelial layer. Both parasites caused destruction of glomerular tufts in heavy infections and an increased number of rodlet cells in the epithelial layer were common in both cases. The two myxosporean species were most abundant during the winter and spring. Extra-sporogonic stages of S. elegans were found only in January and June in the rete-mirabile of the eye, circulating blood and kidney. In infections with S. elegans sex of the host fish was apparently of no significance, whereas significantly lower infestations occurred in male sticklebacks infected with M. gasterostei compared with females. Host size was important in determining the prevalence and intensity of both myxosporean species. Older fish were less heavily infected, possibly due to an acquired immunity or pathogenic effects on the host. A high number of mixed infections indicated that there was no interspeciflc competition between the two parasites. There appeared to be a continuous recruitment of myxosporeans throughout the year. Studies on myxosporean spore shedding suggested that spore production and shedding was continuous throughout the year and was uninfluenced by temperature or season. Gyrodactylus gasterostel was generally more abundant in winter and spring than in summer and autumn, reflecting the greater numbers of small young of the year fish at these times. The age of the host fish was a significant factor influencing the prevalence and intensity of infestation with G. gasterostei. Sex of the host had no apparent influence on infestation. The parasite was highly overdispersed within the host population and its distribution was best fitted by the negative binomial.

x, 154 leaves : ill. ; 29 cm Typescript. (Another copy on microfilm is located in Archives) Thesis (Ph.D.)--University of Oregon Vita Bibliography: leaves 144-154