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Biomedical subjects

Malcolm Potts

Publications and source records attributed to Malcolm Potts.

14 recordsLinked to original sources
PubMed2003

Genomic DNA of Nostoc commune (Cyanobacteria) becomes covalently modified during long-term (decades) desiccation but is protected from oxidative damage and degradation.

Genomic DNA of Nostoc commune (Cyanobacteria) became covalently modified during decades of desiccation. Amplification of gene loci from desiccated cells required pretreatment of DNA with N-phenacylthiazolium bromide, a reagent that cleaves DNA- and protein-linked advanced glycosylation end-products. DNA from 13 year desiccated cells did not show any higher levels of the commonly studied oxidatively modified DNA damage biomarkers 8-hydroxyguanine, 8-hydroxyadenine and 5-hydroxyuracil, compared to commercially available calf thymus DNA. Different patterns of amplification products were obtained with DNA from desiccated/rehydrating cells and a liquid culture derived from the dried material, using the same set of primers. In contrast, a reproducible fingerprint was obtained, irrespective of time of rehydration of the DNA, using a primer (5'-GWCWATCGCC-3') based upon a highly iterated palindromic repeat sequence present in the genome. In vitro, the desiccation of cccDNA led to loss of supercoiling, aggregation, loss of resolution during agarose gel electrophoresis and loss of transformation and transfection efficiency. These changes were minimized when DNA was desiccated and stored in the presence of trehalose, a non-reducing disaccharide present in Nostoc colonies. The response of the N.commune genome to desiccation is different from the response of the genomes of cyanobacteria and Deinococcus radiodurans to ionizing radiation.

Cyanobacteria↗
PubMed2003

Clustering mass spectrometry data using order statistics.

Mass spectrometry data is inherently uncertain. Rather than compare peak heights across samples, a comparison can be made of the relative ordering of the peak height across samples. Order statistics are used to provide a distance metric between each ordered list of peak heights from the samples. A principal component analysis is performed on the set of distance vectors to highlight to important components.

Mass Spectrometry↗
PubMed2003

Two pills, two paths: a tale of gender bias.

In Japan, it took over 30 years to register the contraceptive Pill, but it took only six months to approve Viagra. The Pill was developed in an academic institution and no large pharmaceutical manufacturer wished to market it. Viagra was developed inside a big company and actively promoted. In the USA, the Pill was almost removed from the market because of widely publicized reports of deaths, but mortalities associated with Viagra do not make the headlines. Viagra has been promoted by the famous, whilst those who use the Pill do not appear in advertisements. Even theologians have treated these two drugs according to different standards. It is suggested that this asymmetry is not accidental, but is an expression of a deep-seated dual standard that is ultimately driven by biosocial differences in male and female power, and reproductive agendas rooted in human evolution.

Biomedical Research↗
PubMed2003

Unusual water flux in the extracellular polysaccharide of the cyanobacterium Nostoc commune.

The speed of water uptake by desiccated Nostoc commune was found to depend upon the duration of desiccation. The rehydration of desiccated colonies led to marked, time-dependent changes in structure and ultrastructure and fluctuations in the composition of the transcriptome. Physical evaporative water loss is an active process that was influenced by inhibitors of transcription and translation.

Base Sequence↗
PubMed2003

Hypersaline cyanobacterial mats as indicators of elevated tropical hurricane activity and associated climate change.

The Atlantic hurricanes of 1999 caused widespread environmental damage throughout the Caribbean and US mid-Atlantic coastal regions. However, these storms also proved beneficial to certain microbial habitats; specifically, cyanobacteria-dominated mats. Modern mats represent the oldest known biological communities on earth, stromatolites. Contemporary mats are dominant biological communities in the hypersaline Bahamian lakes along the Atlantic hurricane track. We examined the impacts of varying levels of hypersalinity on 2 processes controlling mat growth, photosynthesis and nitrogen fixation, in Salt Pond, San Salvador Island, Bahamas. Hypersalinity (> 5 times seawater salinity) proved highly inhibitory to these processes. Freshwater input from Hurricane Floyd and other large storms alleviated this salt-inhibition. A predicted 10 to 40 year increase in Atlantic hurricane activity accompanied by more frequent "freshening" events will enhance mat productivity, CO2 sequestration and nutrient cycling. Cyanobacterial mats are sensitive short- and long-term indicators of climatic and ecological changes impacting these and other waterstressed environments.

Carbon Dioxide↗
PubMedDate not supplied

Life and death of dried prokaryotes.

The removal of water through air drying damages membranes, proteins and nucleic acids and is lethal to the majority of organisms. Nevertheless, some vegetative cells of bacteria and cyanobacteria survive extreme desiccation. Understanding the mechanisms of their desiccation tolerance is an important issue in cell biology and holds promise for the metabolic engineering of desiccation-sensitive cells.

Adaptation, Physiological↗