Maria Elizabeth Donkin

Maria Elizabeth Donkin
University of Plymouth | UoP · School of Biological Sciences

BSc Biochemistry, PhD

About

48
Publications
7,495
Reads
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1,319
Citations
Additional affiliations
January 2008 - present
University of Plymouth
Position
  • Project Leader OPAL SW
Description
  • OPAL is a UK Project involving 9 universities and other institutions such as the Met Office, Open university, NBN , EA. It is a Citizen Science Research Project involving the public in measuring the health of their environment.
January 1995 - December 1997
University of Plymouth
September 1972 - September 1974
The University of Sheffield
Position
  • PostDoc Position
Description
  • I worked in the Photosynthesis Research group of Professor David Walker FRS for two years after my first degree. We were investigating the performance of chloroplasts isolated from different species of plants.

Publications

Publications (48)
Article
Full-text available
Most beginners are introduced to plant diversity through identification keys, which develop differentiation skills but not species memorisation. We propose that mnemonics, memorable ‘name clues’ linking a species name with morphological characters, are a complementary learning tool for promoting species memorisation. In the first of two experiments...
Conference Paper
With the last pure botany degree closing its doors in 2011, the prospect of a generation unable to identify native plants becomes ever more real. We tested novel botanical identification methods and a grassland survey protocol as part of the participatory project 'Open Air Laboratories.' Experiences in the field 82 novices participated in a grassla...
Article
Full-text available
Bryophytes are a rewarding study group in field biology and the UK bryophyte flora has international importance to biodiversity conservation. We designed an identification key to common woodland moss species and compared the usability of two formats, web-based multi-access and printed dichotomous key, with undergraduate students. The rate of correc...
Article
Full-text available
Taxonomic education and botany are increasingly neglected in schools and universities, leading to a ‘missed generation’ of adults that cannot identify organisms, especially plants. This study pilots three methods for teaching identification of native plant species to forty-three adults engaged in the participatory science project ‘Open Air Laborato...
Article
Reference 13 Kn/Ki = (0.048/0.114) + 1 = 1.419 This shows the non-ionised drug is absorbed faster than the ionised, although, in common with the findings with many other comparatively large, hydrophobic molecules, the effect is not absolute. Phosphate buffer proved to be superior to Tris-chloride buffer since Tris had a pH-dependent effect of its o...
Conference Paper
The use of antifouling booster biocides on boats and ships is of environmental concern as the leached products can affect non-target, highly susceptible phytoplankton organisms. Assessment of phytoplankton health in coastal environments should include a combination of approaches, investigating toxic effects from biochemical level to changes in comm...
Article
Full-text available
Phytoplankton were exposed to 4 antifouling booster biocides (Sea-Nine 211(R), Irgarol 1051(R), diuron and zinc pyrithione) to investigate toxicological responses. Initially, single species/single biocide exposure experiments revealed changes in pigment ratios under all biocide exposures for the prymnesiophyte Emiliania huxleyi, but not for the cya...
Article
Measurements of the stress imposed by a PSII inhibiting herbicide (Irgarol 1051) on the composition of a phytoplankton community was investigated by comparing chemotaxonomy, as determined by high performance liquid chromatography (HPLC), optical microscopy and analytical flow cytometry (AFC). Changes in community structure were induced in microcosm...
Article
The herbicides Irgarol 1051 (2-(tert-butylamino)-4-cyclopropylamino)-6-(methylthio)-1,3,5-triazine) and Diuron (3-(3',4'-dichlorophenyl)-1,1-dimethylurea) are commonly incorporated into antifouling paints to boost the efficacy of the compound towards algae. Previous investigations have identified environmental concentrations of these herbicides as...
Article
A selection of herbaceous plants representing the ground flora around a typical chemical installation in the UK was exposed continuously for 7 weeks to a mixture of six VOCs (acetone, acetonitrile, dichloromethane, ethanol, methyl t-butyl ether and toluene) in open-top chambers. Exposure concentrations were based on predictions of atmospheric dispe...
Article
The relative sensitivity of the reproductive cells of the seaweed Enteromorpha intestinalis to UV-B was assessed by measuring in vivo chlorophyll fluorescence (F(v) variable fluorescence), germination success and growth rates. Zoospores (the asexual reproductive cells) exhibit up to a 6 fold higher sensitivity to UV-B exposure than the mature thall...
Article
Numerous studies have indicated that stress proteins have potential as biomarkers of exposure to environmental contaminants. Analysis of stress proteins in animals, especially Hsp70, has dominated this research area despite increasing interest in the use of plants as pollution monitors. In the present study Hsp70 expression in Enteromorpha intestin...
Article
The random amplified polymorphic DNA (RAPD) technique was used to detect DNA damage in the sublittoral macroalgae Palmariapalmata (Rhodophyta) exposed to both ambient and elevated irradiances of UV-B (280–315 nm). To investigate the potential of this method in ecotoxicological assessments, the qualitative and quantitative modifications in RAPD prof...
Article
A field survey and an outdoor experiment were conducted to evaluate the potential of chlorophyll fluorescence and in vivo absorptance spectra as biomarkers of short-term experimental and long-term solar UV radiation exposure in macroalgae. The eulittoral macroalga Porphyra umbilicalis (L.) (Rhodophyta) and the sublittoral macroalga Palmaria palmata...
Article
Irgarol 1051 (2-(tert-butylamino)-4-cyclopropylamino)-6-(methylthio)-1,3,5-triazine) is a triazine herbicide that is increasingly being used to boost the effectiveness of antifouling paints. Estuarine plants, such as the marine angiosperm Zostera marina L. (eelgrass) may accumulate, and be affected by, Irgarol 1051, in locations with high boat dens...
Article
Enteromorpha intestinalis was exposed to a range of copper concentrations (0-500 μg−1) for 5 days, to assess the effect of copper exposure on stress proteins (Stress-70 levels) and physiology of the seaweed. A second experiment investigated the combined effects of copper and heatshock on Stress-70. Stress-70 was induced by copper exposure, but is n...
Article
Freeze-fracture/cytoplasmic maceration (FF/CM) to expose chloroplast ultrastructure for the SEM was developed for the green alga Enteromorpha intestinalis (Linnaeus) Link, and the results were compared with conventional TEM preparation. Preliminary investigations showed that the method used for higher plants was inadequate to expose algal chloropla...
Article
The photosynthetic fluorescence ratio Fv:Fm, in vivo absorption spectra and ion leakage were evaluated as biomarkers of ambient and elevated UV-B (280 to 320 nm) exposure of the intertidal alga Enteromorpha intestinalis (Chlorophyta) and the sublittoral alga Palmaria palmata (Rhodophyta). Measurements of thallus growth were also used to assess adve...
Article
Water samples taken from the Plymouth Sound locality were analysed for the presence of the s-triazine herbicide Irgarol 1051, which is an ingredient of antifouling paints used on pleasure boats and ships. Irgarol 1051 was detected at all sampling sites within the Sound; the highest levels were found in close proximity to areas of high boat density,...
Article
Two methods for measuring the effect of organic toxicants on the marine macroalga Enteromorpha intestinalis were compared. EC50 data for the effect of C1−C8n−alcohols on neutral red dye retention and ion leakage were used to construct QSARs with log Kow as the only physicochemical parameter. The two QSARs were statistically indistinguishable sugges...
Article
The transmission, reflection and absorption spectra of pods of Pisum sativum L. variety JI 141 were measured at various stages of senescence. These optical properties were correlated with the percentage water content and levels of chlorophyll a, b and total chlorophyll of the pod wall at each stage. Photomorphogenic effects of pod senescence on the...
Article
The effect of alcohols on the retention of neutral red, a vital stain, was investigated for the marine macroalga Enteromorpha intestinalis. The algae were incubated for 24 hrs in a series of non-specific narcotic alcohols, and subsequently exposed to a neutral red solution for 3 hrs. On removal, the stain was extracted into a solvent and the result...
Article
The transmission, reflection and absorption spectra of a range of legumes including Pisum sativum L. were compared. The optical properties of the pea pod appeared to be within the middle of the range of species studied. The optical properties of the pod walls of five different varieties of Pisum sativum were investigated at three stages of developm...
Article
The %transmission, reflection and absorption of the carpel wall of Pisum sativum L. has been compared with other pea tissues: leaf, testa and cotyledon. Although considerable overall differences were found, especially in the levels of light that were transmitted, there were qualitative similarities which correlated with the presence of chlorophyll...
Article
The pod space CO2 was measured in three varieties of Pisum sativum L. which had green, yellow and purple pods. Pod CO2 concentrations were measured under different light intensities and alternating light/dark conditions, as well as during a diurnal cycle, during different stages of development. Results showed that in the green podded varieties the...
Article
After removal of the pod wall, seeds of Pisum sativum L. still attached to the peduncle and vascular tissue were grown from a very early stage in a simple in vitro system supplying a basic nutrient medium. Light was found to enhance growth in this system.
Article
Trifluoperazine and Compound 48/80 are drugs which bind to the calcium activated form of the calcium binding protein calmodulin. In this study these drugs were applied to epidermal strips of Commelina communis L. to see whether stomatal apertures under a range of incubation conditions could be affected by their presence. Significant effects of both...
Article
Some kinetic properties of partially purified phosphoenolpyruvate carboxylase (PEPCase) from guard-cell and mesophyll-cell protoplasts of Commelina communis are described. The PEPCase activity inherent to each cell type was determined and the apparent K m (phosphoenolpyruvate) and K i (malate) were compared. Malate sensitivity was much higher (K i...
Article
‘Wilty’ (JI 1069), a mutant of Pisum sativum, has been examined for its ability to produce abscisic acid (ABA) under water stress. ABA was measured using combined gas chromatography-mass spectrometry and multiple-ion-monitoring employing a deuterated internal standard. In intact droughted plants, ‘Wilty’ produced less ABA than a non-wilty line (JI...
Article
The water relations and stomatal behaviour of a wilty line of pea (JI 1069) were investigated and compared with those of several non-wilty lines (JI 1180, JI 1194, and JI 74). The leaves of the wilty line were found to have a lower percent water content, water potential and diffusive resistance and the dimensions of the stomatal cells were larger t...
Article
Stomata on both upper and lower epidermis of the Argenteum mutant of Pisum sativum were found to respond to light, with no significant difference in behaviour between the two types. Stomata on the lower epidermis also responded to CO2, exhibiting a larger CO2 response than light response. There appears to be a peak of response to light in the absen...
Article
Phosphoenolpyruvate (PEP) carboxylase activity in epidermal extracts of Commelina communis has been compared in the presence of malate and glucose-6-phosphate. The activity of PEP carboxylase was inhibited by increasing malate concentrations at several substrate (PEP) concentrations and changes in both the apparent K m (PEP) and V max values in the...
Article
Microspectrophotometric measurements of the absorption spectra of guard cells of Commelina communis and Allium cepa indicate a high absorbance in the blue region of the spectrum with a maximum at 340 nm. Maximum blue light absorption occurred in the polar regions of the guard cells, with significantly lower absorption in the subsidiary and epiderma...
Article
A comparison of the absorption spectra of both upper and lower epidermal guard cell chloroplasts and mesophyll chloroplasts has been made using microspectrophotometry. The spectra of both chloroplasts indicate that they are broadly similar, although a generally lower absorbance at 670 nm and a higher absorbance between 500-600 nm was observed in th...
Article
Abstract Starch levels in Commelina communis epidermis, were shown to be higher in the dark than in the light, from plants kept under an imposed photoperiodic regime. These changes were also inversely correlated with diffusive conductance (1/diffusive resistance, 1 /R) of the leaves used. Even after advancing the photoperiod by 7 h the changes in s...
Article
A spectrophotometric assay has been used to measure the activity of PEP carboxylase and RuBP carboxylase in the epidermal and mesophyll tissue of Commelina communis. On both a chlorophyll and protein basis the PEP carboxylase activity was always greater in the epidermis than in the mesophyll, whereas RuBP carboxylase activity was always highest in...
Article
Full-text available
Extracts from chloroplasts of spinach, sunflower and four other reductive pentose phosphate (C3)-pathway species were measured spectrophotometrically with or without a modified preactivation procedure. In all six species this modification yielded Km (CO2) values in the range of 7-15 micron and maximum velocities, at 20 degrees C, of 129-431 mumol o...
Article
It is shown that in susceptible barley DDT has a marked effect on cytochrome f responses, and on measurable levels of cytochromes b559LP, b559HP, and b6. These effects, not shown by treated resistant barley, are discussed in the light of known sites of inhibition by DDT of photosynthetic electron transport.
Article
Full-text available
An inhibition of photosynthetic electron transport in susceptible barley following treatment with DDT is accompanied by an accumulation of fructose, glucose, and, to lesser extent, sucrose. There is an accompanying deposition of polysaccharide grains in the chloroplasts, and these are maintained even after a dark period sufficiently long to deplete...
Article
The effect of DDT in resistant and susceptible barley on various photosynthetic electron transport activities involving photosystems 1 and 2 functioning alone and in series is reported. Whereas none of the measured activities in resistant barleys were affected by DDT treatment, in susceptible barley two sites of interaction of DDT with the photosyn...
Article
Intact chloroplasts of sunflower (Helianthus annuus) show only very low rates of 14CO2 fixation or CO2 dependent oxygen evolution, compared with intact chloroplasts of spinach. However, envelope-free sunflower chloroplasts will show good rates in a reconstituted chloroplast system using chloroplast extract. Sunflower chloroplasts can also be used i...
Article
Ferredoxin was isolated from the blue-green alga Anabaena flos-aquae. Its homogeneity was shown by conventional and SDS-polyacrylamide gel electrophoresis, and isoelectric focusing on polyacrylamide gel columns, the latter indicating a pI at ca pH 3·7. The absorption spectrum had, in the oxidized state, maxima at 462, 421, 327 and 276 nm, with a sh...

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