VHF radio-telemetry was used to study individual and seasonal variation in common seal haul-out behaviour in a study area in Orkney, Scotland. The timing of the annual cycle was also described and seasonal changes in behaviour, distribution and abundance were related to the constraints of breeding and the moult. There were consistent seasonal trends in site-use, with some sites being used during the breeding season, and others during the winter. Sex differences in site-use also occurred during the summer, with mothers and pups being seen regularly at some sites, and males predominating at others. A high degree of individual, sex-related and seasonal variation in haul-out behaviour was found. In general, seals spent most time in inshore waters, and hauled out frequently, during the summer. For males, this was especially marked during the moult, whereas females came ashore most regularly during the pupping period. Outside the breeding season, seals left the study area for longer periods, of several days, but regularly returned between trips to haul out. These longer winter trips are believed to represent periods of more intense feeding activity, and it is suggested that the constraints of breeding and the moult restrict seals to shorter feeding trips during the summer. Changes in haul-out behaviour during the moult resulted in common seals being most abundant on land in August. Behaviour was also less variable during the moult, and it is suggested that population surveys should be made at this time of year. An aerial survey was made over Orkney in August 1985 and, in conjunction with telemetric data on haul-out frequency, the results were used to produce a preliminary estimate of the size of the population in this area.

Heat stress inhibits spermatogenesis partly by inducing apoptosis in the testicular germ cells. Using a cryptochid rat model, we identified a temperature-related ESTs 4 (TRS4) transcript from rat testis. Trs4 mRNA is specifically expressed in the mouse and rat testis from postnatal day 21 and 28 days onwards, respectively. Trs4 protein is located mainly in the elongating spermatids and mature spermatozoa at the acrosome and tail regions. Using a yeat-2-hybrid screening, Trs4 was found to bind Gstmu1, Rslh-2 and Ddc8 proteins. To further characterize the functional role of Trs4 in spermatogenesis, and study how Trs4 interacts its binding proteins for cellular functions, we aimed (1) to screen putative ES cells with Trs4 floxed allele for knockout mice generation, (2) to generate Trs4 deletion constructs and study the cellular localization of Trs4 and its putative binding partners in transfected spermatocyte GC-2spd(s) cell line, (3) to study how heat-treatment regulates the expression of Trs4 and apoptotic molecules. The Trs4 conditional targeting vector was constructed by flanking exons 4-6 with two LoxP sites and electroporated into ES cells. After screening of 480 clones, positive ES cell clones were identified by Southern blotting using 5’- and 3’- probes. Three putative positive clones were identified carrying the floxed allele. Trs4 protein contains putative ubiquitin-like motif (a.a. 119-224), IQ-calmodulin binding motif (a.a. 334-362) and a overlapping bipartite nuclear localization signal (BNL) (a.a. 346-362). Transfection of EGFP fused Trs4 truncated protein demonstrated that the IQ-calmodulin binding motif and BNL signal was important for localization of Trs4 protein in the cytoplasmic/Golgi regions; while the N-terminal contains ubiquitin-like motif and the C-terminal regions direct the expression of the EGFP-fusion protein mainly to the nucleus. The full-length sequence of Trs4 binding partners: Gstmu1, Rshl-2 and Ddc8 were cloned into the pDsRedmonomer-C1 vector, giving red fluorescence protein in the transfected cells. They were colocalized with EGFP-Trs4 in the cytoplasm of the cells, confirming that Trs4 and its interacting protein is likely interact with each other in vivo. As Trs4 colocalize with Gstmu1, a modulator of mitochondrial-dependent pathway in apoptosis, it is suggested that Trs4 is an upstream regulator of apoptosis under heat treatment in germ cells. The functional roles of Trs4 protein Trs4 and apoptotic molecules. The Trs4 conditional targeting vector was constructed by flanking exons 4-6 with two LoxP sites and electroporated into ES cells. After screening of 480 clones, positive ES cell clones were identified by Southern blotting using 5’- and 3’- probes. Three putative positive clones were identified carrying the floxed allele. Trs4 protein contains putative ubiquitin-like motif (a.a. 119-224), IQ-calmodulin binding motif (a.a. 334-362) and a overlapping bipartite nuclear localization signal (BNL) (a.a. 346-362). Transfection of EGFP fused Trs4 truncated protein demonstrated that the IQ-calmodulin binding motif and BNL signal was important for localization of Trs4 protein in the cytoplasmic/Golgi regions; while the N-terminal contains ubiquitin-like motif and the C-terminal regions direct the expression of the EGFP-fusion protein mainly to the nucleus. The full-length sequence of Trs4 binding partners: Gstmu1, Rshl-2 and Ddc8 were cloned into the pDsRedmonomer-C1 vector, giving red fluorescence protein in the transfected cells. They were colocalized with EGFP-Trs4 in the cytoplasm of the cells, confirming that Trs4 and its interacting protein is likely interact with each other in vivo. As Trs4 colocalize with Gstmu1, a modulator of mitochondrial-dependent pathway in apoptosis, it is suggested that Trs4 is an upstream regulator of apoptosis under heat treatment in germ cells. The functional roles of Trs4 protein / published_or_final_version / Obstetrics and Gynaecology / Master / Master of Philosophy

Spermatogenesis takes place in the seminiferous epithelium and it is a tightly regulated process that produces spermatozoa from spermatogonia. During spermatogenesis, germ cells have to traverse the seminiferous epithelium, from basal to adluminal compartment and finally reach the luminal edge of the seminiferous tubules at spermiation. During the transit of germ cells, they have to get across the blood-testis barrier (BTB), which is formed by adjacent Sertoli cells. Thus, although BTB is considered as one of the tightest blood-tissue barrier, the BTB undergoes cyclic restructuring to “open” transiently for the translocation of germ cells. However, the integrity of the BTB has to remain intact as the BTB is essential for the developing germ cells behind the barrier. For example, the BTB serves as an immunological barrier to “seal” developing germ cells from the systemic circulation. Since how the BTB restructuring is regulated remains elusive, the study herein aims to provide some information regarding to this events. The importance of the BTB to spermatogenesis was demonstrated by treating rats with 50 (lowdose) or 250 mg/kg b.w (high-dose) of adjudin. Although the BTB of rats was perturbed in both groups at week 6 post treatment, as shown by an in vivo BTB functional assay, the BTB of the low-dose group was found to have “resealed” at week 20 whereas the BTB of the high-dose group remained disrupted. Besides, despite almost all germ cells were depleted in both group of rats upon week 2 post treatment, spermatogonia were still present in the testis of rats no matter high- or low-dose of adjudin was used. However, spermatogenesis only recovered in low-dose treated group, which have an intact BTB. This suggests that after spermatogenesis is disrupted, its regeneration of spermatogenesis needs more than the existence of spermatogonia in which an intact BTB is required. After demonstrating the necessity of the BTB for spermatogenesis, the next question I addressed was how its restructuring was modulated. The involvement of mammalian target of rapamycin (mTOR) in manipulating the BTB was investigated. mTOR is able to form two distinct signaling complexes namely mTOR complex 1 (mTORC1) or mTORC2 by assembling with raptor or rictor, respectively. rpS6, which is a downstream molecule of mTORC1 was activated specifically during BTB restructuring and knockdown of rpS6 in cultured Sertoli cells was able to promote the TJ-barrier by inducing deposition of F-actin and BTB proteins at the cell-cell interface, suggesting the role of phosphorylated rpS6 is to “open” the BTB for the transit of spermatocytes. Moreover, the knockdown of rictor led to perturbation of TJ-barrier formed by cultured Sertoli cells via a PKC-α depending actin reorganization, causing internalization of BTB proteins. This indicates mTORC2 is necessary for the maintenance of the BTB and hence the two mTOR complexes work antagonistically to regulate the BTB in which mTORC1 is activated to promote the BTB restructuring while the expression of mTORC2 is essential to sustain the BTB integrity. / published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Although spatial navigation is predominantly guided by allothetic visual cues, idiothetic cues can obtain control when familiar visual cues are not available. In path integration, the current position and orientation are estimated and continuously updated using idiothetic cues, which are contributed by the vestibular system. Previous studies have revealed that vestibular lesioned rats were significantly impaired in path integration. Rats assessed in the current study received neonatal treatment with either VU0240551 (KCC2 blocker) or muscimol (GABAA receptors agonist) in the vestibular nuclei. Path integration ability appears to be intact in rats receiving either treatment. However, VU0240551-treated rats displayed impairments in their ability to resolve conflicting allothetic and idiothetic cues. Therefore, it is proposed that the ability to properly resolve a cue-conflict requires the normal polarity of GABA and/or glycine action in the vestibular nuclei during the neonatal period. / published_or_final_version / Physiology / Master / Master of Medical Sciences

published_or_final_version / Zoology / Master / Master of Philosophy

No description available.

No description available.

No description available.

No description available.