Browsing by Subject "Molecular"

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    Comparative metabolomic profiling of phenolics in the desiccation-tolerant “resurrection plant” Myrothamnus flabellifolia (Myrothamnaceae) using conventional and green chemistry-based solvent systems
    (2019) Bentley, Joanne; Verboom, Tony
    Myrothamnus flabellifolia (Myrothamnaceae) belongs to a group of ±300 angiosperm species known as “resurrection plants” that exhibit vegetative desiccation tolerance. They are able to survive dehydration to an air-dry state, tolerating up to 95% cellular water loss for a prolonged period of time followed by the rapid recovery of metabolism in the tissues within 24–72 h of rehydration. Prolonged cellular water loss is deleterious and is associated with the production of reactive oxygen species (ROS), which causes cellular degeneration, and ultimately, death. Resurrection plants have evolved various strategies to ameliorate this damage, including biochemical, ultrastructural, and anatomical modifications. Myrothamnus flabellifolia is widespread across southern Africa, and within its range it occurs in regions that experience high, moderate, and low rainfall; the low rainfall region also being associated with longer dry periods. Myrothamnus flabellifolia has historically been used for the treatment of chest infections, uterine pain, and gingivitis, and, more recently, has been shown to exhibit various phytochemical activities relating to the potential inhibition of diabetes, reverse transcriptases, and microbes. Previous studies have found M. flabellifolia extracts to contain high levels of polyphenolic compounds, which act as protectants against the ROS-induced damages caused by prolonged periods without moisture. However, a global assessment of the phenolic constituents, including anthocyanins, present in M. flabellifolia from across its geographic range is currently lacking. As the biosynthesis of compounds is likely to be subject to a fair amount of environmental control, an evaluation of the molecules present in this species from across its geographic range is warranted. Thus, in this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics approach was used to screen for phenolic compounds, including anthocyanins, from leaf material sampled in the field from eight populations representing the western, southern, and eastern range of the species distribution. Putative phenolic compounds were identified based on their MSE spectra in the negative ionisation and positive ionisation (for anthocyanins) modes. Their potential roles in the ROS-scavenging capacity of this plant were also discussed. Using this information, multivariate statistics were used to compare the phenolic profiles of the different populations in order to ascertain whether plants from the different regions were associated with any particular phenolic signature, and this was also evaluated against a phylogenetic hypothesis for species relationships based on three non-coding chloroplastic markers. Additionally, a preliminary green chemistry-based extraction protocol using Natural Deep Eutectic Solvents was also used to further screen for phenolic compounds, and this was compared against the conventional organic solvent system. Several phenolic compounds not previously detected in M. flabellifolia were putatively identified, many of which, based on an assessment of the literature, are associated with high antioxidant activity. The phylogenetic analyses suggested that the Namibian plants are more highly diverged than the South African and Malawian plants. The metabolomics analysis corroborated the DNA analysis, in that the most differentially expressed ions in the Namibian population were able to discriminate these samples from both the Malawian and South African samples. While the phenolic profiles of the samples collected from the same countries were similar, there was reasonable withinpopulation variability in those collected from South Africa and Malawi. Conversely, the Namibian samples exhibited far less variability, suggesting that a particular suite of protective compounds may be required for survival in that comparatively drier region. A Natural Deep Eutectic Solvent-based system successfully targeted phenolics in M. flabellifolia and thus constitutes a potential future green chemistry solution for phytochemical investigations in medicinal plants.
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    From proteomics to biotechnology. using the resurrection plant eragrostis nindensis to genetically engineer drought tolerant crops
    (2024) Van Der Pas, Llewelyn; Farrant, Jill Margaret; Hitzeroth, Inga; Henk, Hilhorst; Rafudeen, Suhail
    Global climate change is increasingly putting pressure on finding innovative solutions to ensure future food security in particular to developing African nations. Of great relevance are regionally adapted crops, known as orphan crops, which tend to have very little economic value but can provide a source of alternative food security. Vegetative desiccation tolerance is a remarkable feat of selective evolution and is only present in a small number of angiosperms. The ability of some plants, such as Eragrostis nindensis to survive complete cellular water deficit provides an attractive model for discovery-based omics to not only understand the mechanisms involved in driving desiccation tolerance but to explore the feasibility of potential target genes for orphan crop improvement. The work presented herein was aimed at complementing a transcriptomic study using the same leaf tissue from that study to evaluate the changes from RNA to protein and to determine whether there were proteomic signatures that could differentiate the desiccation-tolerant non-senescent (NST) leaves from the desiccation-sensitive senescent (ST) leaves. The data presented here illustrate that several important metabolic pathways are significantly reprogrammed, that only a small subset of proteomic-matching transcripts were translated, and that proteomic differences between the NST and ST were noted despite their being significant similarities between the two in general oxidative and osmotic stress. For instance, the prevention of ferroptosis and accumulation of raffinose synthase and starch synthase in the NST exclusively illustrated that small and subtle increases in protein abundance are likely responsible for enabling resurrection in the NST and not in the ST, which we hypothesise here is likely due to sacrificing of ST upon rehydration as a means to act as a source of nutrition for the NST during resurrection. The study also focussed on functional characterisation of a heat shock 70 protein from E. nindensis as a target for genetic engineering. The selected EnHSP70 was shown to localise to the chloroplast and was able to undergo liquid-liquid phase separation in vitro in a protein concentration and polyethylene glycol dependent manner which could have broad impacts on its role in maintaining proteostasis. In Arabidopsis thaliana, overexpression of EnHSP70 resulted in a stunted germination phenotype whereas expression in BL21 Escherichia coli did not enhance tolerance towards salt or mannitol stress. Furthermore, incubation of EnHSP70 with lactate dehydrogenase did not confer improved thermotolerance. Taken together, the selected HSP70 from E. nindensis did not appear to be involved in stress response and is likely involved with general proteostasis. Lastly, a method for generating embryonic calli from Eragrostis tef is presented with the goal of using this developed protocol for the genetic improvement of the Ethiopian orphan crop.
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    Omics-based molecular techniques in oral pathology centred cancer: prospect and challenges in Africa
    (2017) Adeola, Henry A; Soyele, Olujide O; Adefuye, Anthonio O; Jimoh, Sikiru A; Butali, Azeez
    BACKGROUND: The completion of the human genome project and the accomplished milestones in the human proteome project; as well as the progress made so far in computational bioinformatics and "big data" processing have contributed immensely to individualized/personalized medicine in the developed world. MAIN BODY: At the dawn of precision medicine, various omics-based therapies and bioengineering can now be applied accurately for the diagnosis, prognosis, treatment, and risk stratification of cancer in a manner that was hitherto not thought possible. The widespread introduction of genomics and other omics-based approaches into the postgraduate training curriculum of diverse medical and dental specialties, including pathology has improved the proficiency of practitioners in the use of novel molecular signatures in patient management. In addition, intricate details about disease disparity among different human populations are beginning to emerge. This would facilitate the use of tailor-made novel theranostic methods based on emerging molecular evidences. CONCLUSION: In this review, we examined the challenges and prospects of using currently available omics-based technologies vis-à-vis oral pathology as well as prompt cancer diagnosis and treatment in a resource limited setting.
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    Omics-based molecular techniques in oral pathology centred cancer: prospect and challenges in Africa
    (BioMed Central, 2017-06-05) Adeola, Henry A; Soyele, Olujide O; Adefuye, Anthonio O; Jimoh, Sikiru A; Butali, Azeez
    Background: The completion of the human genome project and the accomplished milestones in the human proteome project; as well as the progress made so far in computational bioinformatics and “big data” processing have contributed immensely to individualized/personalized medicine in the developed world. Main body: At the dawn of precision medicine, various omics-based therapies and bioengineering can now be applied accurately for the diagnosis, prognosis, treatment, and risk stratifcation of cancer in a manner that was hitherto not thought possible. The widespread introduction of genomics and other omics-based approaches into the postgraduate training curriculum of diverse medical and dental specialties, including pathology has improved the profciency of practitioners in the use of novel molecular signatures in patient management. In addition, intricate details about disease disparity among diferent human populations are beginning to emerge. This would facilitate the use of tailor-made novel theranostic methods based on emerging molecular evidences. Conclusion: In this review, we examined the challenges and prospects of using currently available omics-based technologies vis-à-vis oral pathology as well as prompt cancer diagnosis and treatment in a resource limited setting.