No description available.

No description available.

Typescript, etc. / Digitized by Kansas State University Libraries

The objective of this research was to indirectly determine the existence of a possible retinal-endocrine pathway activated, or Inhibited, by artificial fluorescent light as evidenced by it subsequent effects on bone metabolism. Forty-eight male Long-Evans post-breeder rats, half of which were bilaterally orbitally enucleated, were used in this experiment. A 21-day pretreatment diet contained calcium and phosphorus, each at a level of 0.2% of the diet, with no dietary vitamin D. During the last seven days of this period the animals were in complete darkness. For the 12-week experimental period, the diet contained 0.6% calcium and 0.4% phosphorus, and oholecalciferol wets administered the first day by intubation. During this time, four groups of 12 animals each, half of which were bilaterally orbitally enucleated, were exposed to either ultraviolet lights, cool green lights, Vita-Lite (full spectrum) lamps, or kept in complete darkness in specially constructed environmental boxes. On the first and last day of the experimental period, the left femurs were x-rayed and blood was sampled. The serum of the animals was analyzed for alkaline phosphatase, total calcium and total phosphorus. Bone density was determined. Femur ash was measured for total calcium and total phosphorus. Under all lighting conditions, for both the sighted and enucleated rats, the parameters measured in the serum declined. For serum alkaline phosphatase, the sighted rats under the cool green lights had the least change; the sighted in darkness had the greatest decline. The least change in serum total calcium occurred for both the sighted and enucleated rats under the cool green lights, whereas the greatest decline was for the sighted rats under the Vita-Lite lamps and the enucleated under ultraviolet lights. The sighted rats under the cool green lights had the highest percent ash per gram of dry fat-free weight; the sighted under the Vita-Lite lamps had the lowest. The highest ash calcium was in the sighted rats under the cool green and the Vita-Lite lamps. By both methods of bone density measurements, specific gravity and densitometry, the sighted rats under the cool green lights had the greatest loss. Overall there appeared to be more significant differences among the sighted animals for the various lighting conditions than for the enucleated. Also the enucleated rats had less extreme variations from the mean than the sighted. The results of this study suggest that the light mediated by the pbotoreceptors of the retina of the sighted rats produced an effect on bone metabolism. / Graduation date: 1982

No description available.

Experiments were designed to study the effects of various intensities and durations of light during early development on meristic variation in kokanee and sockeye salmon (Oncorhynchus nerka), pink salmon (O. gorbuscha) and in rainbow trout (Salmo gairdneri). An experiment with sockeye was designed exclusively to test the period of fixation of vertebrae. Among the salmon species rates of hatching and yolk-sac absorption were fastest under the longer light durations and higher intensities. In sockeye and pink an increasing rate of yolk-sac absorption was correlated with increasing amount of light. In trout the rate of yolk-sac absorption showed the opposite results. Mortalities were high under all the experimental conditions. Although meristic variability observed was deemed to be phenotypic yet the affects of selective mortality could not be entirely excluded. Abnormalities in the vertebral column were prevalent in the ‘pre-urostylic' region. The occurrence of abnormal vertebrae was correlated with light only in sockeye. The activities of the pituitary and thyroid glands of trout showed a positive correlation with higher amounts of light. Sockeye scale counts, along the lateral line and on the oblique rows from the origin of dorsal and anal fins to lateral line, were lowest under conditions of higher light and longer durations. Fin ray numbers in all species were the lowest at high light intensities and longer durations. Vertebral counts were lowest at high light intensities and long durations in pink salmon and rainbow trout, but higher in sockeye. At lower light intensities and durations results were variable. Vertebral counts of sockeye increased with increasing light at temperatures of both 8°C and 12°C. Differences among lots at 8°C were significant but those among comparable lots at 12°C were not. The action of light on meristic variability was weak at the higher temperature. It was found in sockeye that vertebral numbers were not fixed before 142 D° and that the period of sensitivity was prolonged (142 D° to 300 D°). / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Call number: LD2668 .T4 1960 M33

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

Female golden Syrian hamsters are seasonally breeding animals, capable of maintaining continuous estrous cycles when the daylength is 12.5 hrs. or longer. In shorter photoperiod (SP) the ovaries of anovulatory animals are characterized by few small growing follicles, an absence of corpora lutea and extensive hypertrophied interstitium. Steroid-histochemical studies revealed that enzymes related to steroidogenesis show intense activity in the interstitial tissue of SP-exposed animals. The major objectives of these studies were to examine SP-induced hormonal and ovarian changes which occur prior to onset of the acyclic condition in inbred LSH/SsLak hamsters. Other experiments explored hormonal changes in the absence of ovarian hormones and the interaction of SP and steroids. Initial results revealed that the LSH/SsLak hamster ceased estrous cyclicity between 14 and 31 days of SP exposure, a response far more uniform than generally seen in outbred hamsters. Experiments carried out in SP-exposed cyclic animals indicated that the secondary FSH surge and follicular recruitment were not affected by SP treatment, follicular recruitment were not affected by SP treatment, and that no major changes in gonadotropin levels and ovarian steroids were present on individual days of the estrous cycle. Once the animals were anestrous, daily gonadotropin surges were present and pituitary gonadotropin contents increases. Serum PRL levels showed a slight, yet significant, decrease in SP cycling animals followed by a further reduction in pituitary and serum levels after animals ceased cycling. Medial basal hypothalamic LHRH contents did change in SP, yet there was a significant increase in the preoptic area, and LHRH became significantly elevated in both areas after the animals became anestrous. Ovarian histology revealed fewer corpora lutea and a slight shift from healthy to atretic antral follicles. Experiments carried out in ovariectomized SP-treated animals showed that serum gonadotropin levels were significantly reduced, and that estrogen treatment was either equally or less effective in reducing levels in SP animals. In contrast, PRL levels did not change and responded in a dose dependent way to estrogen treatment. Although the studies yielded no definite proof, the result suggest that SP impairs the maintenance of follicular growth leading eventually to the acyclic state.