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- Cavender, James C., et al.
(author)
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New dictyostelid cellular slime molds from South Africa
- 2018
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In: Phytotaxa. - : MAGNOLIA PRESS. - 1179-3155 .- 1179-3163. ; 383:3, s. 233-251
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Journal article (peer-reviewed)abstract
- A distributional study of the dictyostelid cellular slime molds (dictyostelids) of South Africa was carried out during 2006 as part of the Global Biodiversity of Eumycetozoans project based at the University of Arkansas and funded by the National Science Foundation Samples of soil/humus collected from 31 study sites yielded a total of 881 clones, with an average density of 210 clones/gram for all samples in which dictyostelids were detected. Eighteen different species were represented by one or more clones, and six of these could not be identified. These six species are described herein as new to science. In addition, information is provided on the ecological distribution of all of the species of dictyostelids now known to occur in South Africa.
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- Grapensparr, Liza, et al.
(author)
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Co-transplantation of Human Pancreatic Islets With Post-migratory Neural Crest Stem Cells Increases beta-Cell Proliferation and Vascular And Neural Regrowth
- 2015
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In: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 100:4, s. E583-E590
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Journal article (peer-reviewed)abstract
- Context: Neural crest stem cells (NCSCs) are capable of substantially improving murine islet function by promoting beta-cell proliferation. Objective: The present study aimed to investigate the potential of NCSCs to stimulate human beta-cell proliferation, and improve neural and vascular engraftment of human islets. Design, Setting, and Subjects: Human pancreatic islets from 18 brain-dead cadaveric donors (age range, 19-78 y) were obtained through the Nordic Network for Clinical Islet Transplantation. beta-cell proliferation and graft function was investigated at our experimental laboratory. Intervention and Main Outcome Measures: Human islets were transplanted, either alone or together with spheres of NCSCs. beta-cell proliferation, as well as islet neuralandvascular densities, were assessed by immunohistochemistry. Graft blood perfusion and oxygen tension were measured using laser-Doppler flowmetry and Clark microelectrodes, respectively. Results: Two days posttransplantation, the number of Ki67-positive beta-cells was doubled in human islets that had been exposed to NCSCs. Similar findings were obtained in vitro, as well as with EdU as proliferation marker. Four weeks posttransplantation, NCSC-exposed human islet grafts had much higher neural and vascular densities. The newly formed blood vessels were also functional, given that these human islets had a substantially higher blood perfusion and oxygen tension when compared with control transplants. Conclusion: We conclude that exposure to NCSCs stimulates human beta-cell proliferation, andthat these cells improve both the neural and vascular engraftment of transplanted human islets. NCSCs are a promising cellular therapy for translation into clinical use.
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- Khalil, Sammar
(author)
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Resilience of growing media
- 2014
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In: Acta Horticulturae. - 0567-7572 .- 2406-6168. ; 1034, s. 371-378
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Conference paper (peer-reviewed)abstract
- Growing media in horticultural cropping systems inhabit a number of microorganisms including bacteria and fungi. This number is low at the beginning of the growing period and increase rapidly after the introduction of the plants. Analyses using viable count indicated stability of growing media at the bacterial amount of 1010 cfu/g of fresh root and at 106 cfu/ ml for the nutrient solution. Microflora inhabiting growing media can be of beneficial or harmful character. Root pathogens such as Pythium, Phytophthora and Fusarium are common pathogens in these media. In reaction disease control has focused on beneficial microorganisms as a tool for disease management. The natural role of the resident microflora, manipulation of the growing media by addition of different biocontrol strains separately or in combination or nutritional amendments to enhance the antagonistic capacity of the microflora are aspects in focus. A reduction in disease incidence by 50-100% by the resident microflora was reported. In different investigations introduction of biocontrol strains has shown a positive effect on disease reduction. However, the type of growing medium has shown to have an impact on the performance of such strains. Moreover, nutritional amendments using organic material such as compost, other C or N sources in order to increase the size of the microbial community and activity have been reported. Special attention has also been directed towards the activity of microbial communities in growing media as well as in compost during processing. Measurements of microbial respiration, nitrification process and enzyme activity have been used as indicators for microbial activity. Further, assessments of microbial communities, during the cultivation period indicated dominance of bacteria in inorganic growing media such as rockwool and fungi in the organic ones like peat. Although the microflora in the growing media plays an important role in disease control, other factors such as water content, pH and nutrients are also of importance. To define sustainable horticultural production systems, mathematical models may help to combine widely differing data as mentioned above. This might result in early warning systems. Information on molecular basis as well as bioinformatics information about disease management in growing media and composts is needed.
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| 7. |
- Khalil, W. K. B., et al.
(author)
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Genotoxicity Evaluation of Nanomaterials : DNA Damage, Micronuclei, and 8-Hydroxy-2-deoxyguanosine Induced by Magnetic Doped CdSe Quantum Dots in Male Mice
- 2011
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In: Chemical Research in Toxicology. - : American Chemical Society (ACS). - 0893-228X .- 1520-5010. ; 24:5, s. 640-650
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Journal article (peer-reviewed)abstract
- Quantum dots (QDs) are a novel class of inorganic fluorophores which are gaining widespread recognition as a result of their exceptional photophysical properties and their applications as a biomarker and in molecular biomedical imaging. The aim of this study was to evaluate the in vivo genotoxicity in mice exposed to CdSe quantum dots of average size 5.0 +/- 0.2 nm and CdSe doped with 1% cobalt ions of similar size. The quantum dots are surface modified using mercaptoacetic acid (MAA) in order to be biocompatible and water-soluble. The MAA-QDs were given to the mice orally at doses of 500, 1000, and 2000 mg/kg by weight of MAA-QDs. Bone marrow and liver samples were collected after two and seven days of treatment. The results indicated that after two days of treatment, the high dose of doped MAA-QDs was significantly able to induce DNA damage, formation of micronuclei (MNs), and generation of DNA adduct (8-hydroxy-2-deoxyguanosine, 8-OHdG). However, increasing DNA damage and the frequency of MNs formation as well as the generation of DNA adducts were observed with both the undoped MAA-QDs (2000 mg/kg) and doped MAA-QDs (1000 and 2000 mg/kg) after seven days of treatment. The results of our study indicate that exposure to high doses of pure MAA-QDs or MAA-QDs doped with cobalt has the potential to cause indirect in vivo genetic damage, which may be attributed to free radical-induced oxidative stress in mice.
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- Khalili Ardali, Zohreh, et al.
(author)
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Assessment of Recreational Value in a Protected Forest Area Considering the New Environmental Paradigm (Case Study: Helen Forest, Southwestern Iran)
- 2024
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In: Sustainability. - : MDPI. - 2071-1050. ; 16:7
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Journal article (peer-reviewed)abstract
- This study investigates the recreational value of the Helen protected forest area, incorporating the new environmental paradigm into economic valuation. Visitors’ willingness to pay and its association with scores reflecting the new environmental paradigm were assessed through contingent valuation and a dual-dimensional questionnaire. Two models are employed: a base model with socio-economic variables and a model integrating new environmental paradigm. Results indicate that 83.04% of visitors are willing to pay for recreational use. The proposed amount, visit frequency, new environmental paradigm, age, gender, education, and income were found to significantly influence the acceptance of willingness to pay. Results indicated a strong positive correlation exists between new environmental paradigm and willingness to pay, highlighting the influence of environmental perspective. Average willingness to pay per household per visit is IRR 190,390.4 (USD 0.53), translating to an annual recreational value of IRR 22,629,264,215 (USD 64,088) for the entire Helen forest. The average new environmental paradigm scores for visitors stand at 57.36, with the statement “plants and animals have similar rights to humans” receiving the highest score of 28.4. These findings emphasize the importance of considering environmental perspectives in managing recreational sites. Integrating a new environmental paradigm into valuation methods can inform sustainable management strategies that balance economic development with environmental conservation and social well-being.
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