Typescript. Includes vita and abstract. Also available for download via the World Wide Web; free to University of Oregon users. Bibliography: Includes bibliographical references (leaves 125-138). Description: xii, 138 leaves : ill. (some col.) ; 29 cm.

The ribonucleotides in the chorioallantoic membrane of 12-day-old chick embryos have been isolated by ion-exchange chromatography and characterized by their spectrophotometric and paper chromatographic properties. The following nucleotides were identified: adenosine-5' phosphate (AMP), uridine-5' phosphate (UMP), cytidine-5' phosphate (CMP), uridine-5' diphosphate galactose (UDPGal), uridine-5' diphosphate N-acetyl hexosamine (UDPNAHexosamine), guanosine-5' phosphate (GMP), cytidine-5' diphosphate (CDP), uridine-5' diphosphate (UDP), adenosine-51 diphosphate (ADP), guanosine-5' diphosphate (GDP), cytidine-5' triphosphate (CTP), uridine-5' triphosphate (DTP), adenosine-5' triphosphate (ATP), and guanosine-5' triphosphate (GTP). Quantitative determinations of these nucleotides were made on the basis of their ultraviolet absorption at 260 mμ. Similarly, concentrations of these nucleotides were estimated in 12-day-old chorioallantoic membranes after infection with vaccinia virus. Larger amounts of ribonucleoside-5' phosphates were present in the infected tissue at 4 and 12 hours after infection. The amounts of ribonucleoside-5' triphosphates were decreased. In tissues where, it is believed, synchronous infection occurred, the amounts of ribonucleoside-5' diphosphates and triphosphates were markedly lower than in controls after 12 hours of infection. Infection in the presence of tritium₌labelled thymidine showed that the amount of labelled thymidine-5' mono-, di-, and triphosphates had increased after 4 hours and that the amounts of these nucleotides subsequently decreased. / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

Fecundity data were obtained for twelve species of British Columbia freshwater fishes by use of a displacement method. Data for an additional fourteen species were obtained from the literature. Fecundity relative to a unit body weight was considered superior to absolute fecundity for use in racial studies. Egg diameter was significantly larger in anterior than in posterior regions of ovaries from five species tested. Egg diameter was positively correlated with fork length within and between species. Amongst twenty-six freshwater species considered, egg diameter was found significantly correlated with reproductive characteristics. Fish with eggs of large mean diameter generally have amber to salmon colored eggs, non-adhesive eggs, long incubation periods, redd construction, stream spawning and variable spawning season. Fish with eggs of small mean diameter have white to yellow eggs, adhesive eggs, short incubation period, lack of redd construction, variable spawning location and spring or summer spawning season. / Science, Faculty of / Zoology, Department of / Graduate

Experiments on the viability of salmonoid eggs and sperm under conditions of artificial storage were conducted at Lloyd's creek, Nelson creek and Cultus lake, B.C., from May to November, 1948. In May and June, preliminary experiments on the holding of Salmo gairdnerii kamloops eggs at Lloyd’s creek indicated the feasibility of the storage, especially at low temperatures. In October, further experiments at Nelson creek on Oncorhynchus keta eggs and sperm resulted in the development of a storage technique which was subsequently employed at Cultus lake in November. At Cultus lake, mature O. keta eggs were held in sealed, sterile 500 cc. Mason jars, one third full of eggs, for multiples of 12 hours up to 192 hours (8 days) at temperatures averaging 3.5°C. The O. keta sperm were held in 2 ounce screw-cap jars, approximately 5cc. of milt in each jar, under conditions similar to those for the eggs. Controls were run in all cases. The stored eggs and sperm were fertilized with, or used to fertilize, fresh sperm and eggs. The fertilized eggs were incubated for 24 hours. The eggs were then examined under the dissecting microscope for, evidences of cleavage. Two hundred egg lots for each time period were examined and the percent infertility determined. The results showed that O. keta eggs may be stored for 108 hours, under these conditions, with less than 20% infertility. The O. keta sperm may be held for 36 hours with less than 10% infertility. Beyond 36 hours, under the conditions of this experiment, the sperm results were erratic. The use of these results for fish cultural practices and for the salvage of mature eggs and sperm is suggested. / Science, Faculty of / Zoology, Department of / Graduate

Eggs of Pacific herring were exposed to air for different periods of time in simulation of tidal effects on spawn deposits at varying beach heights. The maximum exposure range was 2/3 of a 24 hour day corresponding roughly to the exposure of eggs at 4 meters above mean low tide on the British Columbia coast. Egg size, spawning fish length, and egg clump size were examined as secondary factors modifying the effect of exposure. Incubation time dropped from 19 to 18 days with only two 2-hour periods of exposure per day and thereafter fell slowly. It is suggested that oxygen deprivation triggered a hatching response for the initial drop, whereas the gradual decrease was due to a higher air temperature increasing metabolism. Hatching mortality rose steadily from an unexposed 13% to 31% at maximum exposure time, with significantly higher contributions from eggs of smaller fish and smaller egg clumps. Larval length at hatching for the unexposed eggs was 7.7 mm.; lengths for all degrees of exposure were similar (7% less than for no exposure). Larval weight (body plus yolk) remained relatively constant (0.099 mg.) until the longest exposure period when it dropped to 0.087 mg. This decrease coincided with similar sharp trends in incubation time and hatching mortality, and suggests a "critical point" near the upper experimental range of exposure, above which eggs stand little chance of normal development or survival. Beach surveys to note possible egg size stratification, although suggesting the deposition of larger eggs at the top levels, proved inconclusive, but point up the possibility that a heavy fishing pressure which reduces mean fish size might detrimentally affect potential stock recruitment via the intertidal exposure effect on the spawn. / Science, Faculty of / Zoology, Department of / Graduate

Environmental factors (extracellular macromolecules) possibly operating in somite differentiation were examined by using an in vitro system with myogenesis as the end point. It was found that differentiation depended on the time of removal of the somitic tissue from the host, i.e. between stages 17 and 26 (2½ to 5 days of age), and the question was raised as to the relation of these observations and the appearance of glycosamino-glycans (mucopolysaccharides). A review of the literature revealed that no information was available on this subject so that an examination of the time of appearance, distribution, and nature of the glycosaminoglycans and neutral polysaccharides in the axial region (dermatome, myotome, scleratome, neural tube and notochord) of the developing chick embryo during early somite differentiation was necessary. It became apparent that both histochemical and biochemical analysis were required to identify, quantify, and localize the glycosaminoglycans since histochemical techniques alone limit the interpretations possible because interference from proteins and glycoproteins could not be ruled out. Histochemical analysis indicated that there was very little sulphated anionic glycosaminoglycan present in the early embryonic stages examined. The cytoplasm of cells in all axial areas contained strongly acidic material, but extracellularly, sulphated anionic glycosaminoglycans were almost all confined to the notochordal sheath. The extracellular matrix in all areas contained weakly acidic anionic glycosaminoglycans. With development, the weakly acidic anionic glycosaminoglycans increased in concentration in most areas, but most noticeably in the neural tube and scleratome. The concentration of sulphated anionic glycosaminoglycans also increased and they began to appear in the extracellular matrix in all areas although never attaining the deep staining intensity demonstrated by the weakly acidic anionic glycosamino-glycans. By stage 25, however, the extracellular matrix of the scleratome around the notochord was mostly sulphated anionic glycosaminoglycans. Testicular hyaluronidase digestion suggested that most of the stainable material was either hyaluronic acid or chondroitin 4- and/or 6-sulphate (chon-croitin sulphates A and/or C). A small amount of strongly acidic anionic glycosaminoglycan present in the scleratome, neural tube and notochord was polysulphated. Biochemical analysis confirmed that the weakly acidic anionic glycosaminoglycan was hyaluronic acid and that the sulphated anionic glycosaminoglycan was mainly chondroitin 4- and/or 6-sulphate (chondroitin sulphate A and/or C). Only trace amounts of dermatan sulphate (chondroitin sulphate B) were present. A small amount of heparin could be present since some glucosamine was present in the sulphated fractions. This heparin could account for the polysulphated material observed with histochemical staining. On a quantitative basis, the hyaluronic acid concentration (uronic acid/gm dry wt. of tissue) was at a peak between stages 21 to 25 and was greater than the chondroitin sulphate concentration up until stage 25. After that stage, the chondroitin sulphate concentration began to increase very rapidly, concomitant with the formation of cartilage around the notochord, and the hyaluronic acid concentration began to decline slowly. Thus, whereas the hyaluronic acid content was 2½ times greater than the chondroitin.sulphate content in stage 17 embryos, this ratio was almost completely reversed by stage 28 due to the rapid increase in chondroitin sulphate. Histochemical staining supported these findings. It would seem that the increase in sulphated anionic glycosaminoglycans is directly related to cartilage formation while the high hyaluronic acid content present during stages 21 to 25, a time in development when myotube formation and scleratome cell aggregation and orientation are occurring, may play some more general developmental role in somite differentiation. / Science, Faculty of / Zoology, Department of / Graduate

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