No description available.

<p> In my thesis I investigated whether loss of growth hormone receptor (GHR) signaling affects post-natal skeletal muscle development and regenerative ability in adult male mice, and whether the effect is via insulin-like growth factor-1 receptor (IGF-1R) signaling. Mouse models were used that had a post-natal muscle-specific loss of GHR signaling (<b>mGHRKO</b>), insulin-like growth factor receptor/ insulin receptor (IGF-1R/IR) signaling (<b>MKR </b>), and loss of both GHR and IGF-1R/IR signaling (<b>mGHRKO/MKR</b>). The loss of GHR signaling did not alter muscle <i>igf-1</i> expression, fiber cross sectional area, fiber type proportions, or regenerative fusion ability. Further more, loss of IGF-1R/IR signaling decreased regenerative ability. In conclusion, my data suggests that GHR signaling does not play a role in post-natal skeletal muscle development or regenerative fusion ability, and that IGF-1R/IR signaling has an effect that is independent of direct GH effects on muscle, though may be affected by systemic GH/IGF-1 function.</p>

No description available.

x, 193 leaves : ill., tables, photos ; 26 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1977

Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Pathology, 1977.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 91-104).

Thesis (Ph. D.)--University of Wisconsin, 1964. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaf vi.

A brief summary of previous literature on vertebrate chromatic responses is presented. The influence of pituitary preparations on the responses of the melanophores of teleosts and of other chromatic vertebrates is examined and a new classification of teleost melanophore responses proposed. The time relations of melanophore and erythrophore response in Phoxinus and melanophore responses in Ameiurus and Rana to injections of teleost pituitary material have been examined. A method of assay, using Phoxinus as test animal, for the melanophore-aggregating hormone is proposed. The distribution of minnow melanophore-aggregating and erythrophore-dispersing, and frog melanophore-dispersing activity in the minnow pituitary closely mirrors the distribution of the meta-adenohypophyseal cells. Experiments with peptic and tryptic digestion suggest that these factors are polypeptide in nature. The influence of alkaline extraction on these factors has been examined and it is suggested that the results can be interpreted in terms of a single polypeptide hormone. All three factors are substantially soluble in alcohol. Electrophoretic analysis of teleost pituitary material failed to separate the minnow melanophore-aggregating activity from the minnow erythrophore-dispersing and frog melanophore-dispersing factors. Similar results were obtained with paper and column chromatography. The responses of hypophysectomised spinal-sectioned Phoxinus are, qualitatively, the same as those of spinal-sectioned fish with intact pituitarios. The erythrophore response of Phoxinus is stronger in black-adapted than in white-adapted fish. The fbihumoral hypothesis' of Hogben and Slome (1931,1936) has been critically examined. The time relations of colour change provide no evidence in favour of a two-hormone control. It is concluded that the evidence in favour of a bihumoral control of teleost melanophores is insufficient to deny the possibility that these responses are in fact under the control of a single, polypeptide, hormone.

The structure and histology of the pituitary gland of two species of teleost, Herichthys cyanoguttatus and Cichlasoma nigrofasciatum, is described. Seven cell types can be recognised. Two groups of P.A.S.+ve, A.F.+ve cyanophils in the meso-adenohypophysis are associated with the production of the thyrotrophic and gonadotrophic hormones; it is suggested that the P.A.S.+ve acidophils in the metaadenohypophysis produce a chromatophorotrophic hormone. The blood supply of the pituitary in cichlids of different ages has been studied. The development of the pituitary of Herichthys and the time at which the cell-types become histologically differentiated is described; comparisons are drawn with the developing pituitary of Cichlasoma. Histological differentiation of the first thyrotrophs coincides with the initial secretion of colloid in the thyroid but the results of experiments in which specimens of Herichthys were reared in thiourea solution indicate that pituitary influence on thyroid activity is not established until a later stage. Thiourea treatment from an early age affects not only the development of the thyroid and thyrotrophs but also that of the swim-bladder, melanophores and skin. The mechanism of these disturbances is discussed. The effect on the pituitary of long-term adaptation to both white and black backgrounds has been studied in several species ofteleost and in Rana. Chromatic adaptation is accompanied by cytological changes in the pars intermedia of Rana, and in certain cells in the meta-adenohypophysis of Phoxinus, Salmo and Cichlasoma but not in Carassius or Ameiurus. The cell types in this region of the pituitary are not histologically comparable in different species; the cellular changes in Phoxinus and Rana can be related to the release of melanophore concentrating- and dispersing hormones respectively but such a correlation has not proved possible for other species. Interpretations of the cytological appearance of the meta-adenohypophysis and intermediate lobe under different conditions are suggested and the functions of the chromatophore-regulating hormone are discussed.

The structure, histology and blood supply of the pineal organ of the minnow are described. Its nerve connections are studied and their possible role in the colour response of the fish is suggested. No evidence is found for hormonal activity of the pineal organ in the colour change of the minnow. The structural modifications of the pineal organ in normal and blind fish in conditions of constant light, temperature, darkness and different background tints are described. Constant illumination together with constant temperature in the blind fish result in a very much folded pineal organ. It is suggested that a non-functioning photoreceptive state of the eyes (condition present in these blind fish and the normal and blind fish kept in darkness at a higher temperature) is responsible for the stimulation of the pineal organ at a constant higher temperature. The antagonistic reaction to the pituitary in relation to the ovaries is also described. Changes following hypophysectomy also suggest an antagonistic relation between the pineal organ and the pituitary. The relations of the hypothalamo-hypophyseal system and its vascular supply are discussed with regard to the neurosecretory function of the nucleus preopticus and itspreoptico-hypophyseal tract and the transport and storage of the neurosecretory material. The developmental differentiation of the system is studied. Seasonal changes in the hypothalamo-hypophyseal neurosecretory system, especially the NPO-activity, are correlated with the reproductive cycle and their significance is discussed. An attempt is made to interpret the relation of the optic nerves with the preoptico-hypophyseal tract. The relation of the latter with the commissura transversa is described, especially with regard to the possible relaying of messages from the cerebellum to the pituitary gland. Aspects of the structure and cytology of the pituitary are described. Seasonal changes, especially in the meso-adenohypophysis, can be correlated with the reproductive cycle. Some effects of hypophysectomy on the hypothalamic complex and on the gonads and thyroid gland are described. In this connection some study is made of the morphology and blood supply of the thyroid gland. Possible interrelationships are further investigated by observing the effects of gonadectomy on the pineal organ, nucleus preopticus, pituitary and thyroid glands. The effects upon these structures in normal and blinded fish of illumination, background tint and temperature are also studied.