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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Male-female Coevolution in Bruchid Seed Beetles

Liljestrand Rönn, Johanna January 2009 (has links)
Male-female coevolution is at the heart of biology. It is responsible for much of the diversity we see in behaviour and morphology, and it is thought to be an important engine of speciation. The pattern of intersexual coevolution is well established in many taxa, yet understanding of the processes responsible for male-female coevolution remains incomplete. By studying interspecific variation within a closely related group of species, we can gain important information about how traits and behaviours have evolved. In the work done for this thesis, we studied a group of seed beetle species. Our results show that male-female coevolution has been a strong force in shaping both behaviour and morphological traits that are associated with mating and reproduction such as, morphology of male and female genitalia and remating behaviour. The evolution of harmful male genitalia has often been suggested to be a product of sexually antagonistic coevolution, but understanding of these extraordinary adaptations is limited. By combining comparative and experimental methods we show that as seed beetle males evolve more spiny genitalia, harm to females is elevated. We provide evidence for the correlated evolution between these antagonistic adaptations in males, and a female counter adaptation (the amount of connective tissue in the copulatory duct). We also demonstrate that imbalance of relative armament of the sexes affects evolution of the costs and benefits of reproduction. As males evolve genitalia that are more harmful relative to the level of female counteradaptation, costs associated with mating for females increase and population fitness is depressed. Our results unveil a coevolutionary arms race between the sexes and are consistent with a proposed link between sexual conflict, species’ viability and the risk of extinction.
72

Comparative Seed Morphology and Phylogenetics : Case Studies in Basal Angiosperms (ANITA) and Asterids (Lysimachia, Ericales)

Oh, Il-Chan January 2009 (has links)
The first half of the thesis deals with the seed morphology of members of the ANITA grade at the base of the angiosperm phylogeny (Amborella, Nymphaeales, Illiciales, Trimeniaceae, and Austrobaileyaceae), especially Illiciaceae and Schisandraceae. Seed characters support a major division between the New World and Old World species of Illicium. Fossil seeds previously assigned to Illiciaceae were re-evaluated. In Schisandraceae, seed and leaf epidermal characters were added to a previously published morphological data matrix. Phylogenetic analysis using the extended data matrix shows that Kadsura and Schisandra appear to be supported as monophyletic sister taxa by a number of synapomorphies in reproductive and vegetative characters. Fossil seeds from the Eocene of North America show some similarities to the modern Schisandra glabra from North America, whereas fossils from Europe are more similar to modern Asian species. In the second half of the thesis, seed morphology of Lysimachia and closely related taxa (Anagallis, Ardisiandra, Asterolinon, Glaux, Pelletiera, Trientalis) was investigated. The phylogenetic relationships among the endemic Hawaiian species of Lysimachia was also studied, using nuclear ribosomal DNA (ETS, ITS) and chloroplast DNA (rpl16, rpl20-rps12, rps16, trnH-psbA, trnS-G) sequence data. The seeds in Lysimachia and related taxa vary in, e.g., shape, seed coat structure and surface patterns. Seed surface patterns are mostly congruent with molecular phylogenetic relationships. A reticulate surface pattern is diagnostic for, e.g., the subgenus Palladia and the Hawaiian endemic subgenus Lysimachiopsis. Mapping seed characters onto a recent molecular-based phylogenetic tree, reveals that they provide potentially synapomorphic character states for various subclades of Lysimachia. The phylogenetic analysis based on the combined data set using nuclear ribosomal DNA and chloroplast DNA data provides new insights into the relationships within the Hawaiian subgenus Lysimachiopsis. Here our results indicate that earlier taxonomic treatments of the group need to be partially revised.
73

Neonatal Exposure to Highly Brominated Diphenyl Ethers and Perfluorinated Compounds : Developmental Dependent Toxicity and Interaction

Johansson, Niclas January 2009 (has links)
This thesis investigated the developmental neurotoxic effects of neonatal exposure to highly brominated diphenyl ethers (PBDEs) and perfluorinated compounds (PFCs), alone or in combinations, during a critical period of the brains’ rapid growth and development, in mice. The compounds investigated were the decaBDE (PBDE 209), nonaBDE (PBDE 206), octaBDE (PBDE 203), heptaBDE (PBDE 183), and three PFCs, PFOS, PFOA, and PFDA. PBDEs and PFCs have been identified as emerging classes of persistent environmental compounds, present in wildlife as well as humans, and present at higher levels in infants/children, compared to older persons. Individuals can be exposed to these compounds throughout her/his lifetime and newborn/children can be exposed to toxicants both via the mothers’ milk and directly via ingestion and inhalation. The brain growth spurt (BGS) is defined by rapid growth and developmental of the brain. For rodents (mice and rats), the BGS is postnatal spanning the first 3-4 weeks after birth. In humans this period begins during the third trimester of pregnancy and continues throughout the first two years of life. It has been shown that several environmental toxicants can induce permanent disorders in brain function when administered to the neonatal mouse, during the BGS. This thesis shows that highly brominated PBDEs, including PBDE 209, PBDE 206, and PBDE 203 can cause developmental neurotoxic effects, when given directly to the neonatal mouse. Of the investigated PFCs, PFOS and PFOA were shown to cause similar effects as the PBDEs. Furthermore, PBDE 209 and PFOA can at low doses interact and enhance the neurotoxic effects in mice. Effects in the adult animal included; deranged spontaneous behavior, reduced or lack of habituation, decreased learning and memory abilities, and increased susceptibility of the cholinergic system. Both classes of compounds were shown to affect proteins (CaMKII, GAP-43, synaptophysin, and tau) important for neuronal growth and synaptogenesis in the neonatal mouse brain.
74

Methods and Applications in Comparative Bacterial Genomics

Fuxelius, Hans-Henrik January 2007 (has links)
Comparative studies of bacterial genomes, now counting in the hundreds, generate massive amounts of information. In order to support a systematic and efficient approach to genomic analyses, a database driven system with graphic visualization of genomic properties was developed - GenComp. The software was applied to studies of obligate intracellular bacteria. In all studies, ORFs were extracted and grouped into ORF-families. Based on gene order synteny, orthologous clusters of core genes and variable spacer ORFs were identified and extracted for alignments and computation of substitution frequencies. The software was applied to the genomes of six Chlamydia trachomatis strains to identify the most rapidly evolving genes. Five genes were chosen for genotyping, and close to a 3-fold higher discrimination capacity was achieved than that of serotypes. With GenComp as the backbone, a massive comparative analysis were performed on the variable gene set in the Rickettsiaceae, which includes Rickettsia prowazekii and Orientia tsutsugamushi, the agents of epidemic and scrub typhus, respectively. O. tsutsugamushi has the most exceptional bacterial genome identified to date; the 2.2 Mb genome is 200-fold more repeated than the 1.1 Mb R. prowazekii genome due to an extensive proliferation of conjugative type IV secretion systems and associated genes. GenComp identified 688 core genes that are conserved across 7 closely related Rickettsia genomes along with a set of 469 variably present genes with homologs in other species. The analysis indicates that up to 70% of the extensively degraded and variably present genes represent mobile genetic elements and genes putatively acquired by horizontal gene transfer. This explains the paradox of the high pseudogene load in the small Rickettsia genomes. This study demonstrates that GenComp provides an efficient system for pseudogene identification and may help distinguish genes from spurious ORFs in the many pan-genome sequencing projects going on worldwide.
75

Transcription Associated Recombination in Mammalian Cells

Savolainen, Linda January 2010 (has links)
There is increasing evidence that the movement of the transcription machinery through DNA has profound effects on the genomic stability. One such example is a phenomenon known as Transcription Associated Recombination (TAR). Transcription enhances recombination levels to a high degree in all organisms studied, from bacteria to mammals. The underlying causes of the high recombination levels observed are unknown, as are the rationale for the rather riskyhazardous recombination event in this context. Recombination is not a risk-free event; there is e.g. the chancerisk for of loss of heterozygozity, which may eventually lead to tumour formation. So, why is TAR so ubiquitous? This thesis deals with the factors inducing TAR, trying to elucidate the mechanisms catalyzing this event. The proteins involved in executing TAR are unknown in mammals, and one of the aims of this thesis havehas been to investigate the role of well-known DNA repair proteins in TAR. In order to do so, cell lines deficient in crucial DNA repair proteins were stably transfected with a novel recombination construct. Transcription can be controlled over this recombination construct, enabling the detection of transcription associated recombination. We found that TAR is dependent on replication and that inhibition of transcription elongation had no further effect on TAR levels in our system. Further, we found that TAR employs a recombination pathway mechanistically separate from the recombination pathway induced by DNA double strand breaks. This pathway is dependent on BRCA2, a protein required for homologous recombination, but independent of the RAD51 paralog XRCC2. In subsequent studies, we found that the XPD subunit of the combined transcription and repair factor TFIIH is required for TAR, but is dispensable for DNA DSB repair by HR. We went on to investigate the connection between HR repair of UV damages and transcription and found that repair of UV damages requires transcription, but not via the transcription-coupled repair pathway. In conclusion, we found that TAR operates by a recombination pathway separate from DNA double strand break induced recombination. We found a connection with stalled replication, and revealed several of the proteins required for TAR in mammals. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.
76

What is known about genetic variation among Baltic Sea blue mussels and the promise of proteomics. A literature review.

Obaid, Jian January 2009 (has links)
The Baltic Sea is an evolutionary young sea that have developed a low salinity in its water from the fresh water that flows from the north and saltwater that flows from the south of the sea. The low salinity is too low for many marine organisms and too high for many freshwater organisms. Species like the blue mussel, which have adapted to the low salinity, may have developed different protein expression as a result. To study which protein that have been expressed in the organism proteome analysis is often used. 2-dimensional electrophoresis may be the only method that can do this kind of analysis.
77

Klimatanpassade lignoser för Norrland : en studie med historisk tillbakablick, nutidsanalys och blick mot framtiden

Didriksson, Annica January 2009 (has links)
Varför är utbudet av lignoser så begränsat för Norrland? Vilka faktorer spelar in för en växts härdighet, och hur bedrivs och prioriteras arbetet för att bredda produktutbudet av lignoser för växtzonerna V-VIII? Anser personer inom branschen att det idag finns behov av några speciella sorters lignoser för de högre växtzonerna? Hur ser forskarna på klimatförändringar­nas påverkan på klimatet och växterna i framtiden? Detta examensarbete grundar sig på en litteraturstudie och telefonintervjuer, och har till syfte att kartlägga det arbete som gjorts och görs för ett breddat produktutbud av lignoser för Norrland. Syftet har också varit att undersöka vilka sorts lignoser det idag finns ett behov av i växtzonerna V-VIII, vilka svårigheter som finns samt undersöka vilka lignoser som några personer i branschen ser som framtidens lignoser för dessa växtzoner. Avslutningsvis har detta resulterat i några upprättade växtlistor över de lignoser som litteraturstudien och i intervjupersonerna anser vara lignoser på frammarsch eller framtidens lignoser för Norrland.
78

Ett designförslag på en trädgård vid ett särskilt boende för personer med demenssjukdom : en pocessbeskrivning

Myhr, Malin January 2009 (has links)
Sammanfattning Syftet med examensarbetet var att utföra ett designförslag på en trädgård för personer med demenssjukdom. Genom litteraturstudier och enkätundersökning har jag fått kunskap om hur en trädgård för personer med demenssjukdom bör se ut och vad den bör innehålla. När man utformar en trädgård för personer med demenssjukdom är inte syftet att rehabilitera, utan att ge dem god livskvalitet. Detta kan man göra genom att skapa en trädgård med växter och material som stimulerar sinnet. Via enkätundersökningen har jag fått möjlighet att ta del av sådant som vårdpersonal tycker är viktigt i en trädgård för personer med demenssjukdom och vad de tror att de boende skulle vilja göra i en trädgård. Resultaten av enkätundersökningen och litteraturstudierna visar att olika egenskaper och karaktärer i trädgården stimulerar sinnen, skapar välbefinnande, bättre hälsa och livskvalitet. Examensarbetet kommer att resultera i en illustrationsplan och en växtlista innehållande förslag på växter man kan använda sig av i en trädgård för personer med demenssjukdom. Jag vill rikta ett tack till Benita Andersson, min handledare som har varit ett stort stöd. Min familj som stöttat mig under den här tiden och vårdpersonalen på Solgläntan och Skogsgläntan som tog sig tid att fylla i enkäterna som blev en viktig del i arbetet.
79

Hälsofrämjande utemiljöer vid seniorboenden.

Eriksson, Carina January 2009 (has links)
No description available.
80

Seasonal variability in group size of harbor seals (Phoca vitulina) hauled out on glacial ice in Johns Hopkins Inlet, Glacier Bay National Park, Alaska / Säsongsmässig variation i gruppstorlek hos knubbsäl (Phoca vitulina) på isflak i Johns Hopkins Inlet, Glacier Bay National Park, Alaska

Augustsson, Evelina January 2010 (has links)
Individuals are believed to benefit in various ways from living in groups. Some species aggregate to increase foraging efficiency and others for social benefits. Why pinnipeds rest in groups is yet not fully understood, but the most common ecological explanation is the benefit of enhanced predator detection. An alternative explanation for grouping, however, is limitation of resting sites, which might force individuals to aggregate on whatever sites are available, despite increased competition for food or mates. My study is focused on group size of harbor seals (Phoca vitulina) hauled out on glacial-ice sites in Glacier Bay National Park (GBNP), southeastern Alaska. Previous studies have focused on group size on terrestrial haul-out sites, and to date there have been few studies of group size on ice haul-out sites. In GBNP, peak numbers of harbor seals haul out during the pupping season (June) and the molting season (August). During the breeding season, glacial-ice haul-out sites are used primarily by females and pups, and during the molting season by molting seals. Because seals may group as an anti-predator strategy, I hypothesized that group size would differ between seasons, with smaller groups of mainly mothers and pups during June, and larger-sized groups during August. The aim of this study was to quantify seasonal differences in the group size of harbor seals hauled-out on glacial ice in Johns Hopkins Inlet (JHI), GBNP, southeastern Alaska, and in addition, map and evaluate the large-scale (inlet-level) spatial distribution of seals for both seasons. I used digital aerial survey photographs to map seal distributions. Four replicate aerial surveys were conducted in JHI during both June and August, 2007. Digital images were georeferenced and imported into ArcGIS 9.3 where the location of each seal was digitized, and group size calculated. To assess within- and between-season differences in spatial distribution of hauled-out seals, the location of each seal for each survey was plotted in ArcGIS, and compared to a visual assessment of ice coverage. My results show that harbor seals in JHI tend to haul out as single individuals during both seasons, with the exception of nursing mothers with pups in June, and a few larger-sized groups in August. There was no significant difference in group size between seasons. Group size during June varied very little, with almost all seals being either single or in mother-pup pairs. Group size varied more during August, and although most seals hauled out alone, there were a few larger-sized groups during each survey. The relative lack of grouping behavior is contrary to previous research, and it suggests that predation pressure on seals within JHI may be lower than at other sites. The greater frequency of larger-sized groups in August appeared to be related to reduced availability of glacial-ice haul-out sites. Long-term reduction in the availability of glacial-ice haul-out sites in JHI, therefore, might lead to shifts in haul-out behavior of harbor seals, with more seals being forced to haul out in larger groups.

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