Mastergradsoppgaver i biologi
DSpace/Manakin Repository
Mastergradsoppgaver i biologi
Recent additions
-
Pálsdóttir, Elínborg Sædís (Master thesis; Mastergradsoppgave, Feb-2012)[+][-]
Abstract: The carcass use of juveniles, subadults and adults of the two eagle species in Norway, the White-tailed Eagle (Haliaeetus albicilla) and the Golden Eagle (Aquila chrysaetos) was studied in Finnmark, the northernmost county of Norway for two winters, in 2009 and 2010. Artificial carrion was laid out as bait on four peninsulas, along with automatic digital cameras which took picture on 5-15 minutes interval. The pattern of carcass use was evaluated in relation to distance from coast and forest, altitude, peninsula, year and day of the year. Furthermore, I investigated whether there were differences in the time spent scavenging each day. Juvenile eagles of both species and subadult White-tailed Eagles were rare on the carcasses, while subadult Golden Eagles and adults of both species occurred at similar, but overall, rather low frequencies. In general, occupancy on carcass decreases with distance from coast for both species, most clearly so for adult White-tailed Eagles. Subadult Golden Eagles were fairly evenly distributed across the peninsulas. Adult Golden Eagles were more common on the Sværholt and Varanger peninsulas, while adult White-tailed eagles were most common on the Nordkinn and Sværholt peninsulas. I detected no differences between the age groups in time period spent scavenging per day. The intensity of use of the carrion was too low in both eagle species for interference competition for such food resources to be a likely determinant of the spatial and temporal distribution of eagles during the winters in Finnmark. URI: http://hdl.handle.net/10037/4105 File(s) in this item: 1
thesis.pdf (1.485Mb) -
Jakobsen, Jonas (Master thesis; Mastergradsoppgave, Nov-2011)[+][-]
Abstract: The introduction of new hosts into new habitats can bring along hitchhiking parasites, i.e. parasites being introduced with the host. This in particular can be an important dispersal mechanism for autogenic parasites that are otherwise restricted by the natural movement of their fish hosts. In this study, the effect of a local host introduction on the parasite communities of three-spined sticklebacks in two subarctic lakes, was examined by comparing the parasite communities of the “introduced” (Takvatn), versus that of the “founder” (Sagelvvatn) population. Seasonal variation and inter-lake differences in abundance was also integrated in the study. The study revealed great similarity between the parasite communities du to similar ecosystems, close geographical proximity, and the facts that the only two autogenic stickleback specialists present in the systems had been introduced with its host. The subtle differences in parasite species richness were explained by accidental infections of parasites of sympatric fish species. URI: http://hdl.handle.net/10037/3812 File(s) in this item: 1
thesis.pdf (4.216Mb) -
Moe, Are Andreassen (Master thesis; Mastergradsoppgave, Nov-2011)[+][-]
Abstract: Ressursdeling og ontogenetisk nisjeskift ble undersøkt hos sympatrisk ørret og røye ved å inkludere stabile karbon- og nitrogenisotoper for å få et mer langtidsintegrert bilde av fiskens næringshabitat og diettbruk. I begge innsjøene benyttet ørreten seg primært av littoralsonen, mens røya tok i bruk alle tilgjengelige habitater. Det ble funnet en tydelig ressursdeling i diett mellom ørret og røye i begge innsjøene. Både diettanalysene og δ13C` viste at ørreten primært benyttet seg av littorale næringsemner i begge innsjøene. Ved økende lengde hos ørret, økte både andelen stingsild i dietten og ørretens trofiske posisjon beregnet ut i fra δ15N. Det var primært de minste lengdegruppene av røye som benyttet seg av profundale næringsemner, som støttes av både diettanalyser og stabile isotoper i begge vann. Både δ13C` og δ15N verdier viser at røya i Sagelvvatn beitet på profundale næringsemner, men med økende lengde gikk de over til pelagiske næringsemner. Det samme mønsteret ble funnet i Takvatnet, men δ13C`verdier gir indikasjoner på at profundale næringsemner utgjorde en mindre andel av dietten hos de minste lengdegruppene. Det konkluderes med at forskjellene i ressursdeling i habitat og diett både innen røye og ørret populasjoner og mellom ørret og røye populasjoner i stor grad kan forklares ut i fra interaktiv segregering mellom artene og ørretens konkurransefortrinn i som bunndyrspiser i littoralsonen. URI: http://hdl.handle.net/10037/3720 File(s) in this item: 1
thesis.pdf (2.553Mb) -
Zhong, Zhijian (Master thesis; Mastergradsoppgave, 16-May-2011)[+][-]
Abstract: Three mechanisms have been implicated for plant microRNAs (miRNAs) to regulate gene expression, i.e. directing target RNA cleavage, transcriptional silencing and translational repression. A great number of target genes of plant miRNAs were predicted using different algorithms and verified through experimental methods. In the present work, one miRNA from Arabidopsis, microRNA 840 (miR840) was initially analyzed through the high-through put sequencing and bioinformatic method (Rajagopalan et al., 2006). MiR840 expresses from the complementary strand of its predicted target gene, AtWhirly3. AtWhirly3 encodes a homolog of the potato transcriptional regulator p24. MiR840 is located between 2 genes, At2g02740 (Whirly 3, Why 3) and At2g02750 (Pentatricopeptide Repeat Protein, PPR). Whirly 3 protein belongs to the Whirly protein family which is one of the main interesting topics in our group. Understanding the potential regulative function of miR840 related to Whirly 3 gene is important to deeply analyze the Whirly 3 protein. Searching the TAIR (http://www.arabidopsis.org) and TIGR (http://plantta.jcvi.org), the two databases give different annotation versions for this AtWhirly3 gene, differing at the length of the 3’ untranslated region. According to the annotation from TAIR, the target of miR840 is only at the 3’ untranslated region (3’ UTR) of Why 3 gene, so this means miR840 only down-regulate the Why 3 gene. But the information from TIGR gives another annotation, Why 3 gene (At2g02740) and its neighbor gene, a PPR gene (At2g02750) overlap with their 3’ UTR where the target site of the miR840 is. This means the miR840 may also be able to down-regulate both the Why 3 and PPR gene, depending on what annotation you take. Therefore experimental analysis is necessary to determine the miR840 target. My master project here is to perform the biological experiments for analyzing the function of miR840. To verify the target genes and study the biological function of miR840. 4 vectors have been firstly constructed and then introduced into Arabidopsis thaliana by Agrobacterium-mediated transformation (1: overexpressed precursors of miR840; 2: overexpressed mutated miR840 target for directing the miR840 lost its normal function; 3: overexpressed Why 3; 4: overexpressed PPR). The mutated miR840 was constructed by the mechanism of target mimicry which through artificial insertion of a mismatch-loop into the cleavage site at the miRNAs target, for making mutated miRNAs targets. The mutated target sites will direct the miRNAs cannot cleave their targets (miRNAs lost their normal function). The expression level of the transgenic plants will be analyzed, the changes of the expression levels observed in the transgenic plant lines could imply the possible role of miR840. The subcellular location of the PPR (At2g02750) protein which is still unknown yet, so the bioinformatic method was used to predicted its subcellular location. URI: http://hdl.handle.net/10037/3719 File(s) in this item: 1
thesis.pdf (1.808Mb) -
Olsson, Elin Anita Maria (Master thesis; Mastergradsoppgave, 16-May-2011)[+][-]
Abstract: Reindeer (Rangifer tarandus tarandus) inhabit the Arctic and have evolved adaptions to meet the climatic challenges in this region. Peripheral heterothermia, which is a heat conserving mechanism in homeotherms during cold exposure, is well documented in the reindeer and manifests itself in tissue temperatures in the extremities well below 10°C. It is, however, unknown whether peripheral heteothermia in reindeer requires efficient vascular counter-current heat exchange, or is simply a result of reduced blood flow to the extremities. Vascular corrosion casts, x-ray pictures, dissections and electron microscopy did not reveal any counter-current rete in the front legs, but the vascular anatomy, with arteria brachialis and vena brachialis running in intimate contact with each other for the full length of the leg, still seems to allow quite efficient counter-current heat exchange. Recordings of brachial blood flow and subcutaneous temperature (Tsc) in the front legs of winter insulated reindeer subjected to ambient temperatures (Ta) of 20°C, -10°C and -30° suggest that the initial drop in Tsc seen in reindeer when exposed to moderate cold (-10°C) is primarily the result of use of a circulatory pattern enabling counter-current heat exchange, while decreasing blood flow appears to be a secondary mechanism when Ta falls further towards -30°C. URI: http://hdl.handle.net/10037/3718 File(s) in this item: 1
thesis.pdf (2.169Mb)
Search Munin
Browse
-
All of Munin
-
This Collection
Help
Munin is powered by DSpace 1.6.2
The University Library of Tromsø, N-9037 Tromsø
Tel: +47 77 64 40 00, E-mail: munin@ub.uit.no