/library/oar/handle/123456789/57571 2025-11-05T21:15:40Z 2025-11-05T21:15:40Z /library/oar/handle/123456789/122375 2024-05-21T14:57:33Z 2020-01-01T00:00:00Z

Title: Isolation and characterization of mycorrhizae and mycorrhiza-like associations from soil of the Maltese Islands Abstract: Studies of soil fungal diversity in the Maltese Islands are still considered sporadic and limited. The aim of the present work was to carry out studies to investigate the presence of Trichoderma spp. within the ascomycota, ectomycorrhizae and arbuscular mycorrhizae in the Maltese Islands and eventually to effect their isolation and preservation on different substrates. Soils samples were initially cultured Potato Dextrose Agar medium at a temperature of 27°C in the light. After microscopic inspection, fast-growing colonies with phialides and conidiophores which are typical of Trichoderma growth, were selected for monoconidial isolation. In total, nine dinstinct isolates were made using a monoconidial isolation technique, and their growth patterns and rate of growth were measured and photographically recorded. To help in identification of isolates, micromorphological studies were carried out using different staining techniques for light microscopy. In addition, DNA barcoding was carried out. Seven strain of the Trichoderma harzianum complex were identified for different soils and media in the Maltese Islands as well as another two new records of Trichoderma species namely T. virens and T. citrinoviride. These Trichoderma isolates were preserved in sterile 99% glycerol, sterile distilled water, Synthetic Nutrient Agar, Potato Dextrose Agar, and spent coffee grounds. Spore and mycelium viability were confirmed after one year for all of them. The search for ectomychorrizae was conducted during the rainy season between 2015 and 2019. Ten records were confirmed, and of which two are new records for the Maltese Islands namely Russula ochrosporea and Hebeloma quercetorum were discovered. For Hebeloma quercetorum it was also possible to measure the rate of growth of the basidiocarp. For the arbuscular mycorrhizae study, plant-traps were set up and their presence was confirmed as vesicles within the roots of Daucus carota, Carya illinoinensis and Quercus ilex. As far as is known, this was the first record of arbuscular mycorrhizae detected in Maltese soils. Description: M.SC.BIOLOGY

2020-01-01T00:00:00Z /library/oar/handle/123456789/107482 2023-03-20T13:29:01Z 2020-01-01T00:00:00Z

Title: An integrated assessment of the impact of anchoring on seafloor integrity (MSFD Descriptor 6) within a major bunkering area of the Maltese islands Abstract: International shipping is a fundamental driver for the global economy. As the shipping industry grows, so does the demand for high-capacity vessels, which led to concerns on how these vessels interact with the marine environment. While waiting to access port facilities and services, vessels may anchor to reduce fuel consumption and to prevent the vessel from drifting. However, anchoring is one of the primary causes of mechanical disturbance to the seafloor and benthic habitats and ecosystems. Locating and quantifying anchoring pressure would enable the marine environment to be managed better so that damage to the seafloor as a result of anchoring is mitigated. The Automatic Identification System (AIS) can be used for identifying and quantifying the anchoring pressure in those areas under investigation. AIS transmits information (e.g. position, type, size) of a vessel to other vessels and coastal stations. This study aims to assess the anchoring pressure in one of the bunkering areas strategically located around the Maltese Islands by using the AIS data collected by the AIS antenna located at the University of Malta, Msida. Anchoring pressure is determined through the development of an arbitrary index using the AIS data. Additionally, the same AIS data is used to produce several GIS maps depicting the location and size of the vessels within the confines of the bunkering area as mentioned above as well as several plots depicting anchoring pressure based on vessel type, seasonality, and density. Description: M.Sc.(Melit.)

2020-01-01T00:00:00Z /library/oar/handle/123456789/107473 2024-01-30T10:07:26Z 2020-01-01T00:00:00Z

Title: Aspects of ecology of cladocora caespitosa Abstract: Cladocora caespitosa is a temperate, zooxanthellate scleractinian coral, which is endemic to the Mediterranean Sea and adjacent Atlantic areas. This coral occurs on hard substrata in a wide range of illumination conditions, from well-lit to dim light, and at depths ranging from shallow waters, down to around 40 m. Locally, the abundance and state of health of this legally protected species appears to be declining in pristine waters; however, this aspect has not been investigated previously. Therefore, the main aim of the present investigation was to determine the occurrence and abundance of C. caespitosa colonies in local pristine waters, and to assess their state of health. During the present study, C. caespitosa was found to be more abundant in well-lit areas and colony size did not appear to bear any relationship to the depth at which the colonies were found. The present results indicated that more than half (56.8%) of the total polyps assessed were pigmented, however, the remaining polyps (43.2%) appeared to be adversely affected in some way. Most of the latter were mainly dead polyps, while bleached and partially necrotic polyps occurred in fewer numbers. The state of health of the polyps varied between localities, apparently as a result of differences in edaphic factors. This study also assessed algal growth on the colonies of C. caespitosa. A significant relationship between the number of dead polyps and algal biomass was found. It is unclear whether the polyps died as a consequence of being overgrown by the algae or if their demise was caused by other factors, and algal growth occurred subsequently. Data from the present study can be used as a baseline for further investigations on the state of the local C. caespitosa population. Description: B.Sc. (Hons)(Melit.)

2020-01-01T00:00:00Z /library/oar/handle/123456789/96209 2022-05-23T13:05:23Z 2020-01-01T00:00:00Z

Title: Development of matrices for 3D spheroid culture and assessment of their metabolic activity Abstract: Major advancements being made for in vitro cellular studies on cancer are currently employing 3D spheroid models as these are capable of mimicking the behaviour of in vivo tumours and allow a better understanding of the complex mechanisms behind cancer cell progression. The matrix is a useful component as it can also promote biophysical and chemical cues which would resemble the behaviour of the natural extracellular matrix (ECM). The aim of this study was to compare the development of 3D spheroid cultures using different polymers as matrix supports and follow their progress by monitoring their metabolic activity. Specific objectives centred on the development of appropriate encapsulation techniques for 3D spheroid culture. Additionally, the extraction of collagen hydrogel from easily available raw materials was also attempted to reduce the cost. 3D spheroids were generated using the hanging drop technique and they were encapsulated in three different matrices, these being, calcium alginate, collagen and guar gum. The effect of these matrices on 3D spheroid growth and development was then investigated by measuring the diameter over a 7 day period, using 20 spheroids per sample in 2 independent trials. Additionally, the change in cell viability of the 3D spheroids was assessed using the Resazurin reduction assay, using 12 spheroids per sample in 2 independent trials. From the results obtained, it was shown that the calcium alginate promoted the largest increase in spheroid diameter, which on average resulted in a percentage increase of 40 % from days 1-7. This was followed by collagen with a percentage increase of 30 %. The values for the Resazurin reduction assay correspond with that of the growth curves as an increase in diameter was accompanied by a larger number of viable cells. Although collagen was extracted successfully, it was expected to promote a larger increase in size due to its protein content resembling that of the natural ECM. Additionally, the guar gum was not a successful matrix as it did not promote increase in spheroid size. Thus, for the latter two matrices further work is needed to make them optimal for 3D spheroid culture. However, this is still a step forward in bridging the gap for the development of spheroid encapsulation protocols. Description: B.Sc. (Hons)(Melit.)

2020-01-01T00:00:00Z