ix, 179 leaves xxiv : ill. / 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 Microbiology, 1970

xxiii, 171 leaves : ill. + appendix / 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 Animal Physiology, 1973

Thesis (Ph.D.) -- University of Adelaide, Dept. of Microbiology, 1970.

Thesis (Ph.D.)--Flinders University, School of Biological Sciences. / Typescript bound. Includes bibliographical references: (leaves 135-157) Also available online.

Nonmammalian vertebrates possess some unusual features in their hormonal systems/ when compared to mammals. As a consequence, they can make an important contribution in investigations concerning the fundamental mechanisms operating in endocrinology. Such studies concerning androgens include inter alia their effects on developmental aspects in the brain of birds and related singing behaviour; the role of neural enzymes in reproductive processes in fish; and the relation between androgens and the stages of spermatogenesis in amphibia, The present thesis examines the biochemistry of androgens in the Australian lizard Tiliqua rugosa. The major compounds studied were testosterone and epitestosterone, which are known to be present in high concentrations in the plasma of the male animal. Previous investigations are expanded, particularly in the areas of steroid identification and testicular biosynthesis. In addition, preliminary studies on the metabolism in the brain (and other tissues) and plasma protein binding are reported. The presence of epitestosterone as a major free androgen in the plasma of the male lizard was confirmed. Other steroids were found in the sulphate fraction. Testosterone sulphate was the most rigorously identified compound, while some evidence was also found for the presence of conjugated 5-androstene-3β,17-diols, etiocholanolone and dehydroepiandrosterone (DHA). Epitestosterone does not appear to be extensively conjugated in this animal. Steroids were not found to be conjugated as glucuronides. The identification studies employed a novel method of electrochemical detection of steroids. This technique was investigated and extended in the current thesis. Biosynthetic studies were carried out on androgen interconversions in the testis, in vitro. The major enzyme activities detected were 17α-arid 17β-oxidoreductases (17α-OR and l7β-OR) and 3β-hydroxysteroid dehydrogenase (3β-HSD)/isonerase. No evidence was found for the presence of a steroid-17-epimerase that would directly interconvert testosterone and epitestosterone. The 17-oxidoreductases were found to be dependent on the cofactor NBDFH. Testosterone appears to be formed mainly via the 4-ene pathway, whereas epitestosterone is formed from both the 4- and 5-ene routes. The compound 5-androstene-3β, 17α-diol was found to be an intermediate in the synthesis of epitestosterone from DHA. Temperature was found to significantly affect 17α-OR activity (maximum at 32°C). In contrast,17β-OR activity was independent of this factor in the testis. Androgen metabolism in the testis was found to be regulated by cofactors, temperature and season. The major enzyme activities found in the male brain were 17α- and 17β-OR. 3βHSD/isomerase was not found; however a low activity of 5α-reductase was identified. Aromatase activity was not positively identified, but preliminary results suggest that it may be present at low levels. The 17-oxidoreductases were widespread throughout the brain. The 17α-OR was significantly lower in the forebrain than other brain sections. The 170-OR activity did not vary significantly throughout the organ, although there was a trend for its activity to be higher in the midbrain region (containing the hypothalamus in these sections). The concentration of endogenous steroids in brain tissue was estimated by radioimmunoassay. Epitestosterone was found throughout the organ structure, whereas testosterone was found mainly in the midbrain (containing hypothalamic regions in these sections). Correlations between enzyme activities and steroid concentrations in brain regions suggested that the main function of 17α-OR is to produce epitestosterone, whereas the 17β-OR may catalyse a more reversible reaction in vivo. Temperature was found to significantly affect both 17α- and 17β-OR activities in the brain. In contrast to the testis, the maximum activity of the brain enzymes occurred at 37°C. The level of 17α-OR activity in the male lizard (100 nmol/g tissue/h) is the highest reported for this enzyme in vertebrates. Both activities were found to be quantitatively similar in the whole brain homogenates of male and female animals, and did not vary seasonally when examined in the male. The 17-oxidoreductases were also found in most other tissues in T.rugosa, including epididymis, adrenal, kidney and liver (but not blood). This suggests that the high activities of both 17α-OR and 17β-OR are dominant features of the steroid system in this animal. The formation of 11-oxygenated compounds was found in the adrenal, in addition to the formation of polar metabolites in the kidney and liver (possibly polyhydroxylated and conjugated steroids). A preliminary investigation into the plasma binding of androgens was carried out. The insults suggest that there are several binding sites for testosterone; one with high affinity and low capacity; the other with low affinity and high capacity. Binding experiments were carried out at 32°C. At this temperature, specific binding was greater than at 25 or 37°C. From the results of competition studies it was suggested that epitestosterone (with a K(i)= 3 X 10 (-6)M for testosterone binding) regulates the binding of testosterone (K(i)=10(-7)M) and hence the concentrations of the latter steroid as a free compound in plasma. In general, the study has shown that the biochemistry of androgens in the reptile T.rugosa is largely similar to that found in other vertebrates. The major difference is a greatly increased activity of 17α-OR, which causes a higher concentration of 17α-compounds to be present in the tissues of this lizard. The physiological roles for epitestosterone are not yet clear. However it appears from this study that this steroid regulates testosterone concentrations in several tissues by either steroidogenic or binding mechanisms. Several major influences on this regulation include temperature, availability of cofactors and seasonal effects.

Copies of author's previously published articles inserted. / Includes bibliographies. / 3 v. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to provide a comprehensive study of the cytology, innervation and blood supply of the pineal complex in Tiliqua rugosa, a large desert dwelling skink (family: Scincidae), commonly known as the sleepy or stumpy-tailed lizard. The study complements the physiological work already reported and expands the knowledge of the epithalamic region in lizards. Various histological techniques, at both light and electron microscopic levels, are utilised. / Thesis (Ph.D.)--University of Adelaide, Dept. of Anatomy and Histology, 1997

Copies of author's previously published articles inserted. / Includes bibliographies. / 3 v. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The aim of this thesis is to provide a comprehensive study of the cytology, innervation and blood supply of the pineal complex in Tiliqua rugosa, a large desert dwelling skink (family: Scincidae), commonly known as the sleepy or stumpy-tailed lizard. The study complements the physiological work already reported and expands the knowledge of the epithalamic region in lizards. Various histological techniques, at both light and electron microscopic levels, are utilised. / Thesis (Ph.D.)--University of Adelaide, Dept. of Anatomy and Histology, 1997

This research project examined the role of environmental time cues and circadian rhythms in mediating seasonal adjustments in the body temperature and locomotoractivity patterns in the Australian sleepy lizard, Tiliqua rugosa (Gray 1827). The first component of this study investigated whether daily rhythms of behavioural thermoregulation and locomotor activity that T. rugosa displays in the field are endogenous circadian rhythms. In each season, there was significant variation in each of these rhythms in lizards released on laboratory thermal gradients under prevailing light-dark (LD) cycles. Both rhythms persisted when lizards were released in constant darkness (DD) and exhibited the same free-running period suggesting a single circadian pacemaker drives both rhythms. The first component of this study revealed that seasonal changes in the expression of daily behavioural thermoregulatory and locomotor activity rhythms are mediated by the circadian system in T. rugosa. The second component of this project comprised three experiments that determined the relative importance of 24 h LD and temperature cycles (TCs) in entraining the locomotor activity rhythm. In the first experiment, lizards were held under LD 12:12 and were subjected to either a TC of 33:15C in phase with the LD cycle or a reversed TC. Following LD 12:12, lizards were maintained under the same TCs but were subjected to DD. Activity was restricted to the thermophase in LD irrespective of the lighting regime and during the period of DD that followed, suggesting entrainment by the TC. In the second experiment, lizards were held under LD 12.5:11.5 and were subjected to one of three treatments; (1) constant 30C, (2) normal TC (30:20C), or (3) reversed TC. Following LD, all lizards were subjected to DD and constant 30C. Post-entrainment free-run records revealed that LD cycles and TCs both entrain locomotor activity rhythms of T. rugosa. Although there was large variation in the phasing of the rhythm in relation to the LD cycle in reversed TC lizards, TCs presented in phase with the LD cycle most accurately synchronised the rhythm to the photocycle. In the third experiment, lizards were held in DD at constant 30C before being subjected to a further period of DD and one of four treatments; (1) normal TC (06:00 h to 18:00 h thermophase), (2) delayed TC (12:00 h to 00:00 h thermophase), (3) advanced TC (00:00 h to 12:00 h thermophase) or (4) control (no TC, constant 30C). While control lizards continued to free-run in DD at constant temperature, locomotor rhythms of lizards subjected to TCs rapidly entrained to TCs irrespective of whether TCs were phase advanced or delayed by 6 h. The results of this experiment excluded the possibility that masking effects were responsible for locomotor responses of lizards to TCs. This study demonstrated that seasonal changes in the expression of this species‟ daily behavioural thermoregulatory and locomotor rhythms are mediated by a circadian system that is sensitive to both light and temperature. The sensitivity of the circadian system to temperature, in particular, may allow T. rugosa to restrict its activity to times of the year that are thermally favourable. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1521959 / Thesis(Ph.D.)-- University of Adelaide, School of Medical Sciences, 2010