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Prostaglandin F2 (PGF2) secretion is lowest at mid-cycle and highest on day 15 at luteolysis in the cycling guinea pig uterus, and is inversely related to serum progesterone levels. An increase in 17- oestradiol (E2) occurs towards the end of the cycle. The guinea pig cDNAs for cyclooxygenase 2 (COX-2), 15-hydroxyprostaglandin dehydrogenase (PGDH) which catabolises PGF2, and a fragment of cyclooxygenase-1 (COX-1) were cloned. The effect of steroids on uterine PGF2 metabolism in endometrial primary cultures was investigated. COX-2 mRNA expression is correlated to PGF2 secretion. In epithelial cells steroid-modulated changes were observed; the addition of medroxyprogesterone acetate (MPA) to E2-primed cells led to a decrease, and the addition of E2 to MPA-primed cells to an increase, in COX-2 mRNA expression and PGF2 secretion. In contrast, steroid-modulated changes in PGDH transcripts were observed in stromal cells, and were upregulated by the addition of MPA to E2-primed cells. COX-1 transcripts were low and unaffected by treatment in both cell types. The in vitro observations were in keeping with the secretory profile seen in vivo in the cycling guinea pig uterus and suggest a differential role for the uterine stroma and epithelium, the former acting to remove (via PGDH), and the latter to produce (via COX-2) biologically active prostaglandin.;PGDH, COX-2 and COX-1 mRNA and protein expression were also analysed in uterine sections of the cycle and pregnancy. COX-1 mRNA expression was present during the cycle and pregnancy, and upregulated during late pregnancy. COX-1 protein was localised to the whole uterus except during early pregnancy. COX-2 mRNA was detected only at luteolysis. During pregnancy PGDH mRNA was expressed as a layer around the foetus, initially in the endometrial stroma (day 15) and later the luminal epithelium (day 50), providing a barrier between foetally derived PGs and the myometrium. The in vivo results confirmed the in vitro findings and indicate that COX-2 is responsible for the rise in uterine PG output seen during the cycle, and COX-1 during pregnancy.

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This study aimed to: (1) Establish if rodent populations in sewers are separate from surface ones (Sewer Interceptor study) (2) Investigate the numbers and distribution of rats in sewers (Preferred Location study/Long term study/Hot spot study) (3) Identify Rat behaviours that might affect numbers and control measures (Bait trial / Preferred Location study). To achieve these aims sewer rat populations were monitored in the London sewer systems over a 20-year period. More detailed studies on rat behaviour were carried out in sequestered sewer systems. The Interceptor study showed that rats are not confined in the system by water traps and cannot be viewed as a separate population from surface rats. They can, especially during periods of low flow, swim underwater, upstream, in the dark, to access or exit the system. The Preferred Location study showed that rats like to find and use dry locations within the sewer network. There are distinct sets of behaviours, which occur in dry locations and not in wet ones and vice versa. The Bait trial confirmed other studies showing that sewer rats are neophobic and this factor needs to be taken into account when dealing with them. The more rats there were, the shorter the avoidance period. In the experiment here, the mean time until consumption decreased from 8.5 for one rat to 5.5 days for three rats. The Long Term study found that the trend in rat numbers has been in decline over the whole twenty-year period of the study in the location studied. In the first thirteen years of the study, the proportion of bait takes decreased significantly from approximately 0.17 in 1986/87 to 0.03 in 1998/99 (F=17.75, P < 0.001: df 1,11). Since then, the decline has continued with an exponential curve best fitting the data. The Hot Spot study showed that Rats are not evenly distributed throughout the sewer network but occur, year on year in "Hotspots". These were locations, which showed up to 17 times more than the statistically significant level of rodent activity. This activity occurred in the same location year after year although not throughout the entire study period. These locations were statistically significant (p < 0.0001 after using the Bonferroni correction).

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Apodemus sylvaticus and A. flavicollis are distinct but sympatric species in Britain and parts of north-western Europe. Much data exists on the ecology of A. sylvaticus in areas where A. flavicollis is absent. This has been summarised and compared with a new study of a mixed A. sylvaticus / A. flavicollis population in central Essex. In the presence of A. flavicollis the winter average population densities of A. sylvaticus were significantly lower than in single species populations. In other respects investigated (survival, breeding season, movements, habitat selection within woods, annual population cycle) A. sylvaticus ecology did not appear to be affected by the presence of A. flavicollis . A. flavicollis ecology differed from that of A. sylvaticus in the following respects: a. It was rarer---representing about 1/4 to 1/5 of the Apodemus population. b. A. flavicoilis was less selective of habitat within woods but less likely to be resident outside woodland habitats. c. Individuals were more mobile. d. The breeding season may be shorter. In Essex both species of Apodemus are widespread but A. flavicollis does not spread so far into urban areas as does A. sylvaticus nor is it equally common in all woodland areas. There is some evidence that the most favourable woods are those in close proximity to arable land. On a national basis the restricted range of A. flavicollis is difficult to explain but the species seems to show some tendency to favour lowland areas with a mixture of woodland and arable land. If this relationship is genuine then large edge effects must occur. It is suggested that A. flavicollis can avoid competitive exclusion by A. sylvaticus when habitat conditions allow a partial separation of breeding habitat by the two species, and that the two species were brought into competition by man's fragmentation and intermixing of woodland and more open habitats.

Islands are extremely variable habitats, differing in shape, size, degree of isolation, geography and climate. They are often described as ‘natural laboratories’ and have proven beneficial for testing theories on evolution and adaptation. Rodents on islands are often characterised by differences in demography, morphology and behaviour compared to adjacent mainland populations. One of the most notable and extensively reported differences is in body size. Several adaptive theories have been suggested to explain these phenomena, which have been termed ‘island syndrome’, yet few have been empirically tested. The bank vole (Myodes glareolus) is a good model for studying the evolution of island syndrome, being present throughout the British mainland as well as on 13 small offshore islands. Voles on four of these islands exhibit the gigantism characteristic of island syndrome. The aim of this study was to compare insular and mainland populations of voles to determine whether island syndrome is truly an adaptive response to life in insular habitats, or whether it is driven by more random processes such as founder effects and genetic drift. In this thesis, I present data on body size, demography and skull morphology along with phylogenetic analyses based on mitochondrial DNA sequences from island and mainland populations of bank voles around the UK. Whilst I was able to demonstrate insular changes in body size, I was unable to demonstrate any demographic differences consistent with the predictions of island syndrome. Phylogenetic analyses revealed that body size differentiation on islands was not related to phylogeographic history. There was little evidence for a single unifying theory explaining the existence of island syndrome, thus I conclude that this biological pattern is probably caused by multiple environmental and genetic factors.