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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.
1

An Evaluation of Two Presumptive Blood Tests and Three Methods to Visualise Blood

Andersson, Rebecca January 2017 (has links)
The aim of this study was to validate the two presumptive blood tests LMG, LCV and the three visualising blood methods Bluestar Forensics, Lumiscene and the Ruhoff method. The methods’ sensitivity, durability, matrices effects, false positive results and the methods effect on subsequent DNA analysis were studied. DNA analyses were also performed to assess the detection limit of the forensic DNA analysis. Drops of diluted blood were applied on different absorptive matrices and the sensitivity was investigated. The solutions were also placed under different conditions to investigate the durability of the solutions. The solutions were applied upon panels using different chemicals and materials and the false positive results were studied. The DNA analyses were performed by diluting the blood with Bluestar Forensics, the hydrogen peroxide method, the Ruhoff method and deionised water. The study showed that the LMG with a 3 % H2O2 concentration performs the best and it is suited for practical casework. The positive results of LMG was easier to interpret than those of LCV, this is probably due to the fixative agent of the used LCV solution. Bluestar Forensics and Lumiscene did perform similar on the different matrices tested, but the Lumiscene solution had a slightly higher durability. The results strongly indicate that the Ruhoff method can be used without luminol, hence only as a hydrogen peroxide solution (the hydrogen peroxide method). All three visualising blood methods decreases chances of retrieving a positive DNA profile, however the visualising blood methods could be used if the blood cannot be found in any other way. A DNA profile was obtained from the one blood sample analysed at dilution of 1:256 in deionized water.
2

CHARACTERIZING CYST MYCOBIOME AND BIOLOGICAL CONTROL OF THE POTATO AND SOYBEAN CYST NEMATODES

Blaise Jumbam (13175475) 29 July 2022 (has links)
<p>  </p> <p>Plant-parasitic nematodes are amongst the most important pathogens impacting crops. Potatoes and soybean are vital crops for rural livelihoods and essential for food security, but their cyst nematode parasites remain a significant constraint globally. <em>Globodera</em> and <em>Heterodera </em>species are amongst the most damaging and internationally recognized quarantine pests of these crops, causing up to 80% yield loss. Their second stage juveniles (J2s) penetrate the host plant root tips and establish a residence close to the vascular bundle from where they extract nutrients as they complete their life cycle. Restrictions of control chemicals have led to an urgent need for alternative control strategies for cyst nematodes. Biological control is a promising alternative control measure, and fungi possess many characteristics that could make them great biological control agents of cyst nematodes. Most nematode populations are thought to be regulated by their natural enemy community. It is unclear which fungi are best adapted as natural enemies of these parasites and how they might do this. This project aimed to (a) characterize and compare the mycobiome diversity of cyst nematode species; (b) isolate and characterize fungi associated with potato and soybean cyst nematodes (c) screen isolated fungi for their efficacy as biocontrol agents against cyst nematodes; and (d) describe any isolated fungi identified as new and having potential for cyst nematode antagonism. Cyst populations were collected from different regions and screened for fungi using culture-based methods. For our next-generation sequence data analysis, we found differences in fungal community assemblages between center of origin of the potato cyst nematode (Peru; South America) and the regions where these nematodes were introduced such as Europe and North America.  There was no significant difference in fungal community assemblages of cysts collected between the years 2019 and 2020. We characterized fungi associated with the cyst nematodes and found that the most frequently isolated genera were <em>Fusarium, Penicillium, Cylindrocarpon, Phoma, Aspergillus </em>and<em> Verticillium</em>. Filtrates from <em>Trichoderma</em> sp. 2, <em>Alternaria alternata, </em>and <em>Fusarium acaciae-mearnsii </em>were toxic on SCN eggs while <em>Purpureucillium lilacinum, Fusarium proliferatum</em> and <em>Aureobasidium</em> <em>ellingtonae </em>sp. nov. were toxic on PCN eggs and juveniles. A new species of <em>Aureobasidium</em> isolated from the potato cyst nematode (<em>Globodera ellingtonae</em>) for the first time, and having biocontrol potentials against this nematode, was also identified, and described. </p>

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