S. M. Glidewell’s research while affiliated with Royal Botanic Gardens, Kew and other places

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Publications (35)


NMR imaging as a tool for noninvasive taxonomy: Comparison of female cones of two Podocarpaceae
  • Article

April 2002

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86 Reads

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17 Citations

S. M. Glidewell

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G. Duncan

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B. Williamson

Summary • Nuclear magnetic resonance (NMR) imaging was investigated as a tool for the detailed morphological comparison of two species of Podocarpaceae of taxonomic interest; these were difficult to investigate by conventional methods. • Two- and three-dimensional NMR images of female cones of Afrocarpus falcatus and Prumnopitys ferruginea were acquired using a range of protocols. Conventional sectioning and microscopic techniques and low-temperature scanning electron microscopy were used where possible, to corroborate the assignments of the NMR images. • A three-dimensional network of resin canals in Prumnopitys ferruginea was revealed and the presence of resin confirmed by chemical shift imaging. Similar canals in cones of Afrocarpus falcatus did not contain resin but the presence of spoke-like vascular traces passing through the sclerotesta was demonstrated. Marked differences in the structure of the sarcotesta of the two species were readily discernible. • NMR imaging allowed noninvasive retrieval of both internal morphological and histochemical information from single specimens in their natural state in a much shorter time than conventional methods would allow and provides useful data for taxonomic purposes in the Podocarpaceae.


The development of blackcurrant fruit from flower to maturity: A comparative study by 3D nuclear magnetic resonance (NMR) micro-imaging and conventional histology

January 2002

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51 Reads

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20 Citations

The development of fruits of blackcurrant (Ribes nigrum) cv. Ben Alder from flower to maturity was studied non-invasively by nuclear magnetic resonance (NMR) microscopy, using attached and detached fruits, and the images were compared with those from low temperature scanning electron microscopy (LTSEM) and conventional resin histology. The NMR images derived from 2-D and 3-D datasets showed the previously unreported growth of arillar tissues to the extent that they almost completely occlude the locular cavity, but LTSEM and resin histology revealed that no fusion occurs between the arillar tissues and the gelatinous sheath surrounding each seed, or between the arillar tissues and the endocarp. The discontinuities between these tissues cause magnetic inhomogenities which result in these structures being clearly resolved by gradient echo imaging sequences. During seed maturation the endosperm changed from high (bright) to low (dark) signal intensity as lipid reserves formed and solidified, whereas the gelatinous sheath had high signal intensity throughout maturation. The high lipid concentration in the seed was manifested by chemical shift effects in the images and the increasing viscosity of the endosperm was reflected in the decrease in spin–lattice (T1) relaxation times. The funiculi, throughout development of seeds, appeared in NMR images with low signal intensity and 3-D surface-rendered reconstructions illustrated the complexity of the spatial array of seeds and funiculi arising from parietal placentas within the loculus. All other vascular tissues in the pericarp and placentas were resolved as a small bright core surrounded by a dark region, within a matrix of moderate signal intensity. Conventional microscopical studies then showed that the bright core discernible by NMR imaging encompassed an entire vascular bundle whereas the darker surrounding region represented small parenchyma cells with pronounced intercellular gas spaces. Other regions of the pericarp which included extremely large parenchyma cells, however, had few intercellular spaces and consequently gave rise to brighter regions of the image.


The application of multivariate statistical methods to NMR imaging

August 2001

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18 Reads

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1 Citation

Computers and Electronics in Agriculture

Statistical methods are used to integrate the information content in multivariate NMR images which had been obtained using different instrumental settings. Empirical and mechanistic models of multivariate pixel values are compared, making use of a novel reparametrisation of the mechanistic parameters to improve numerical stability. A new approach is presented to integrating the information using colour image displays. Projection pursuit is used to identify optimal instrumental settings in synthetic images. Methods are illustrated using seven cross-sectional NMR microscopy images of a blackberry, which was chosen as typical of fruit specimens with hard tissue distributed in a soft matrix.


Morphology, Anatomy and Ontogeny of Female Cones in Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)

July 2001

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188 Reads

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28 Citations

Annals of Botany

The developmental morphology and anatomy of the female cones of Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae) are described and illustrated, based on observations, histology, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) imaging. Ovulate development is typically podocarpaceous. Ovules are unitegmic, and horizontal or inclined upwards throughout ontogeny; the pollination drop is inverted because of the declinate micropyle. Ontogeny of the epimatium-ovule complex is acropetal, the epimatium developing first. A terminal, distal sterile bract creates a pollen-scavenging area. During development, the whole cone re-orientates through some 270°, and the seed realigns approx. 60° with respect to the receptacle axis. The ‘receptacle’ or podocarpium supporting the seed is formed by gradual fusion of initially free bracts. The structures adnate to these bracts represent homologues of ovuliferous scales; they bear vestigial epimatia which may develop into supernumerary ovules or non-functional epimatia. Thus, female cones ofA. pancheri are vestigially multi-ovulate. NMR imaging effectively and non-invasively revealed the three-dimensional arrangement of vascular bundles and resin canals in the cones. Copyright 2001 Annals of Botany Company


Non-destructive examination of herbarium material for taxonomic studies using NMR imaging
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  • Full-text available

March 2001

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72 Reads

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9 Citations

Edinburgh Journal of Botany

Many taxonomic distinctions are made or refined on the basis of herbarium material that is either dried or preserved in spirit medium. Hitherto, examination of internal structure has only been possible by the destructive sectioning of the preserved material. In this paper, the use of nuclear magnetic resonance (NMR) imaging for the non-destructive, non-invasive, complete three-dimensional structural examination of herbarium material is demonstrated for the first time. The experimental materials were the fruiting structures of two species of Southern Hemisphere Podocarpaceae: Acmopyle pancheri and Podocarpus nivalis. Material dried in accordance with standard herbarium techniques was used, as well as material preserved in spirit and freshly gathered fruits. The dried material was subsequently rehydrated using standard techniques, and protocols established for the specimens. Appropriate selection of NMR imaging parameters allowed a variety of anatomical features to be highlighted on a single specimen. Fresh specimens from living material gave the best NMR signals. Dry specimens gave no signal except from the lipid in the seed, but when rehydrated the images yielded almost as much information about internal structure as did a fresh specimen of the same taxon. Thus, NMR imaging has great potential value as a non-invasive method for obtaining details of the internal structure of fruits and seeds and is particularly useful when, as in the case of Acmopyle, the sclerotesta of the seed is too lignified for sectioning by conventional methods.

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FIG. 1. Morphology of pollen and female cones. Acmopyle pancheri: A, SEM image of saccate pollen; B, microphotograph of a longitudinal section through a female cone showing the obliquely erect ovule and the hook-like micropylar opening. Phyllocladus hypophyllus: C, SEM image of pollen with vestigial sacci (vs); D, microphotograph of a female cone showing an individual erect ovule with attached pollination drop; E, pollination drop after pollination showing sinking pollen (same scale as D). Bars ˆ 10 mm (A and C); 0 . 5 mm (D); 1 mm (B). e, Epimatium; fb, fertile bract; i, integument; lsb, last sterile bract; mf, micropylar fork; mh, micropylar hook; mo, micropylar ori®ce; o, ovule; pd, pollination drop; rc, `resin' canal; s, sacci; vb, vascular bundle.
FIG. 2. Time sequences illustrating the dynamics of pollination drop resorption after experimental pollination. Acmopyle pancheri: shape and size of pollination drop (arrow) prior to pollination (A), immediately after pollen application (B), 30 min (C), 1 h (D) and 1 d (E) after pollination (E, di€erent cone). Phyllocladus hypophyllus: F, a single segment of a phylloclade illustrating dimensions and area displayed in G±J (open box). G, Shape and size of pollinated drop (arrow), unpollinated control drop (cd) and detachedèvaporation control' drop (dd) prior pollination. H±J, Pollination drop immediately after (H), 15 min after (I) and 30 min after (J) pollination. Bars ˆ 1 mm (A and G); 5 mm (F).
FIG. 3. Morphology of female cones. Acmopyle pancheri: A, photograph of a single cone. B, Single slice NMR image in LS plane, labelling as in Fig. 1B. Phyllocladus hypophyllus: C, photograph of a single segment of the compound phylloclade used in NMR pollination experiment prior to exudation of pollination drops. D, Single slice NMR image with control (left) and pollinated (right) pollination drop (arrows), outline drawn manually. Bars ˆ 1 mm. co, Control ovule; o/s, additional ovule/scale complex; po, pollinated ovule.
FIG. 5. Plot of mean intensities of indicated`regionsindicated`regions of interest' (ROIs) on Phyllocladus hypophyllus segment as a function of time since pollination. The inset shows the position of the ROIs on the phylloclade segment. A, Red, pollinated drop; yellow, control drop; cyan, pollinatedside ovule; green, control-side ovule; blue, bract-scale complex; grey, background. B, Magenta, midrib (2nd order axis); red, prib1 ( ®rst 3rd order axis on pollinated drop side of midrib); orange, prib2 (second 3rd order axis on pollinated drop side of midrib); gold, prib3 (third 3rd order axis on pollinated drop side of midrib); bright green, crib1 ( ®rst 3rd order axis on control drop side of midrib); dark green, crib2 (second 3rd order axis on control drop side of midrib); dark cyan, crib3 (third 3rd order axis on control drop side of midrib); grey, background. C, Red, poll1 (area between midrib and prib1); magenta, poll2 (area between prib1 and prib2); violet, poll3 (area between prib2 and prib3); bright green, cont1 (area between midrib and crib1); dark green, cont2 (area between crib1 and crib2); dark cyan, cont3 (area between crib2 and crib3); grey, background. (Terminology adapted from Tomlinson et al., 1989.) The dashed lines are parallel to the time axis to allow easier visualization of changes in intensity as a function of time while displaying several plots on common axes.  
Comparison of pollination mechanisms among Acmopyle, Podocarpaceae (excluding Acmopyle) and Phyllocladus (data for Podocarpaceae and Phyllocladus modi®ed after Tomlinson et al., 1997)
Comparative Biology of the Pollination Mechanisms in Acmopyle pancheri and Phyllocladus hypophyllus(Podocarpaceae s. l.)

July 2000

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575 Reads

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22 Citations

Annals of Botany

The pollination mechanisms of Acmopyle pancheri(Brongn. & Gris) Pilg. andPhyllocladus hypophyllus Hook.f. were investigated by conventional microscopical techniques and by nuclear magnetic resonance (NMR) imaging. Dissimilarities include the orientation of the ovule and type of pollen;Phyllocladus has erect ovules and wettable pollen with vestigial sacci, whereas Acmopyle has more-or-less erect ovules and non-wettable, functionally saccate pollen. Similarities include the mode of formation of the pollination drop and its response upon pollination. In both genera, pollination triggers pollination drop retraction and drop secretion ceases. Neither NMR imaging nor conventional histology of Phyllocladus ovules revealed any specific tissue beneath the ovule which could be responsible for pollination drop retraction. It is more likely, therefore, that the drop is channelled into the vascular supply or the apoplast. These findings invalidate the taxonomic value of the pollination mechanism as a suite of characters traditionally used to separate Phyllocladaceae from Podocarpaceae. Copyright 2000 Annals of Botany Company


Use of EPR and ENDOR spectroscopy in conjunction with the spin trapping technique to study the high-temperature oxidative degradation of fatty acid methyl esters †

February 1998

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12 Reads

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12 Citations

Journal of the Chemical Society Perkin Transactions 2

Free radicals produced during the autoxidation of unsaturated edible oils are extremely short-lived, but are able to react with spin traps to produce adducts with sufficient stability for spectroscopic characterisation at (near) cooking temperatures (353–443 K). EPR spectra have shown that the model esters methyl oleate, linoleate and linolenate each formed three distinct radical adducts with N-tert-butyl-α-phenylnitrone (PBN). These adducts have been further characterised by obtaining spectra under conditions of limited oxygen availability and in the presence of α-tocopherol; two of these adducts corresponded to peroxyl and alkyl radical adducts of PBN, whereas the other was an alkyl adduct of 2-methyl-2-nitrosopropane (MNP), which was formed as a result of decomposition of the PBN peroxyl radical adduct. The origins of the various 1H hyperfine splittings have been determined by using selectively and fully deuterated PBN and selectively deuterated oleate and some of their magnitudes have been confirmed by ENDOR spectroscopy. The results obtained clearly confirm the high temperature oxidation of fatty acid esters to proceed via a different mechanism from that observed at low temperature, and point to significant differences in oxidation mechanisms of monounsaturated fatty acid esters relative to polyunsaturated.


An NMR microscopic study of grape (Vitis vinifera L.)

March 1997

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40 Reads

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27 Citations

Protoplasma

Mature healthy grape berries and berries wound-inoculated with the fungusBotrytis cinerea were examined by1H NMR microimaging using 2D and 3D spin echo and gradient echo procedures. These NMR images were compared with representations obtained by conventional histology, where possible using the same specimens. 3D imaging datasets from excised seeds were reconstructed by surface rendering and maximum intensity projection to allow interpretation of their internal structure. T2-weighted spin echo images revealed the major features of the pericarp, septum and loculi of whole berries. T1-weighted images were less discriminatory of parenchyma tissues in the fruit but revealed the endosperm in seeds as a chemically shifted feature. A non-invasive study by T1-weighted spin echo NMR imaging of infection byB. cinerea over a 6-day period showed that the disease spread throughout the exocarp but failed to spread in the mesocarp, a result confirmed by histological examination of the same specimen. Surface rendering of 3D datasets of excised seeds revealed the two ruminations of the endosperm and the distal location of the chalaza. The position of the embryonic axis was revealed in T2-weighted maximum intensity projections. This noninvasive study revealed the need to apply a range of imaging techniques and parameters to visualise the structural features of the different parts of the grape berry.


Use of Magnetic Resonance Techniques in the Study of Disease and Senescence Processes in Plants

January 1997

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48 Reads

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2 Citations

Phyton; Annales Rei Botanicae

S u m m a r y GOODMAN B.A. & GLIDEWELL S.M. 1997. Use of magnetic resonance techniques in the study of disease and senescence processes in plants.-Phyton (Horn, Austria) 37 (3): (81) -(94). Some applications of NMR microimaging and EPR spectroscopy to the study of disease and senescence processes in plant organs are presented, with emphasis on the non-invasive nature of the techniques. A particular strength of the use of NMR microimaging in research on live specimens is its ability to perform repeated measurements on the same specimen. Images can be generated in either two or three spatial dimensions, depending on the objectives and timescale of any particular experiment. Contrast is determined by a combination of mobile proton concentration and its physical and chemical properties, but at the present time only a very small amount of molecular information is generated. EPR spectroscopy produces information specifically on free radicals and paramagnetic metal-containing species on a whole sample basis. Biological sample volumes that can be used with most conventional spectrometers are extremely limited, however, due to a combination of the small physical dimensions of microwave cavities and the fact that water strongly absorbs microwaves; the latter problem can be overcome to a large extent by freezing the specimen, but this is then at the expense of repeated measurements to obtain dynamic information. Both techniques largely avoid the production of artifacts from sample preparation, which limits the validity of results obtained with destructive analytical techniques, where damage-induced responses may represent an appreciable and unavoidable complication.



Citations (27)


... However, determination of reactive oxygen species such as superoxide ion, hydroxyl radicals, and many more other radicals is relatively less possible in a simple laboratory. Identification and quantification of these active species would require sophisticated equipment to generate information about the nuclear magnetic resonance (NMR) and electron paramagnetic or spin resonance (EPR or ESR) of such species [29]. ...

Reference:

Importance of active oxygen-scavenging system in the recovery of rice seedlings after submergence
Use of Magnetic Resonance Techniques in the Study of Disease and Senescence Processes in Plants

Phyton; Annales Rei Botanicae

... These results were confirmed when the researchers used polyvinylpolypyrrolidone (PVPP) to reduce phenolics from the wine matrix and found a significant reduction of the radical signal measured. In 1995, EPR was used to measure the free radical scavenging capacity of phenolics; superoxide radicals were generated and then trapped with tetramethylpyrrolidine-1-oxide (TMPO) (Glidewell et al. 1995). A reduction in the measured TMPO EPR signals indicated that red and white wines were equally efficient in scavenging the superoxide, while commercial proanthocyanidins and anthocyanidin capsules did not reduce the superoxide free radical signal. ...

Free radical scavenging abilities of beverages
  • Citing Article
  • August 1995

... hirtum), savory and thyme produced ESR spectra accounted for free radicals generated by phenolics, carvacrol and thymol. The conclusion was based on previously known antioxidant properties of these molecules (Deighton, Glidewell, Goodman, & Deans, 1994;Deighton et al., 1993 (Table 4). Among the four oregano extracts, the OH-AO 100°C was the most effective at scavenging superoxide anion free radicals. ...

The chemical fate of the endogenous plant antioxidants carvacrol and thymol during oxidative stress
  • Citing Article
  • January 1994

Proceedings of the Royal Society of Edinburgh Section B Biological Sciences

... Degradation of Chl can have two visible effects on plant leaves (Hendry et al. 1987;Takamiya et al. 2000;Matile et al. 1996;Amir-Shapira et al. 1987;Merzlyak et al. 1999;Park et al. 2007;Pruzinská et al. 2005;Zimmermann and Zentgraf 2005;Kratsch and Wise 2000;Karuppanapandian et al. 2011;Hillman et al. 1994). The first is the colour change from green to yellow or red, which naturally occurs during the season change in autumn and is the most conspicuous and rapid event. ...

The senescence syndrome in plants: An overview of phytogerontology
  • Citing Article
  • January 1994

Proceedings of the Royal Society of Edinburgh Section B Biological Sciences

... The spectrum was composed of six peaks as a result of interaction of the unpaired electron with the 14 N (I = 1) of the nitroxide group and the 1 H (I = 1/2) on the a-carbon of the spin trap. The hyperfine coupling constants are a ( 14 N) = 15.5 G and a ( 1 H) = 2.6 G, which are consistent with a Å Ccentred free radical adduct of POBN (Buettner, 1987;Deighton et al., 1992;Muchenschnabel et al., 2001). Fig. 1A and B shows that free radical intensities decreased with increasing concentrations of Cd when Cd concentration was less than 3.3 mg kg À1 . ...

The involvement of oxygen-derived free radicals in the resistant response of potato tubers toErwinia carotovora
  • Citing Article
  • September 1992

Protoplasma

... When the epimatium is fused with the testa it is either fleshy or papery, forming a sarcotesta-like seed coat (Fig. 6), such as in Parasitaxus, Pectinopitys, Prumnopitys and Sundacarpus, and this also occurs in Retrophyllum, Afrocarpus and some species of Podocarpus (i.e. P. smithii, P. henkelii, P. madagascariensis and P. capuronii) in the Podocarpoid clade (Mill et al., 2001(Mill et al., , 2004Khan and Hill, 2021). ...

Morphology Anatomy and Ontogeny of Female Cones in Acmopyle pancheri
  • Citing Article

... Irradiation of various food products including spices by appropriate doses of g-rays has, for many years, been used for insect disinfestation and microbial decontamination , and as a means of preserving foods (Leonardi et al., 1993; Raffi, 1992; Meier and Stevenson, 1993; Pilbrow et al., 1996; Uchiyama et al., 1996; Desrosiers et al., 1996; Beczner et al., 1988; Glidewell et al., 1996; Goodman et al., 1994: De Jesus et al., 1996). ...

Optimization of experimental parameters for the EPR detection of the ‘cellulosic’ radical in irradiated foodstuffs
  • Citing Article
  • February 2007

... The number of seeds per cone varies in the Podocarpoid clade from one to two, which have, for example, been reported in Podocarpus [51]. Most genera in the Prumnopityoid clade (except Parasitaxus) possess one to two or else multiple seeds per cone, as does Acmopyle and the relict genera Microcachrys; Saxegothaea and Pherosphaera have multiovulate (seeded) cones [52]. Species with one or two seeds per cone generally have larger seed cones than the multiovulate cone. ...

Morphology, Anatomy and Ontogeny of Female Cones in Acmopyle pancheri(Brongn. & Gris) Pilg. (Podocarpaceae)
  • Citing Article
  • July 2001

Annals of Botany

... The tropical clade includes 11 genera, ca. 88% of the species diversity of the family (following Farjon 2010), and contains the most emblematic and wellknown genera of Podocarpaceae (Thomson 1909;Gibbs 1912;Sinnott 1913;Sahni 1920;Schoonraad and van der Schijff 1974;Tomlinson 1992;Del Fueyo 1999;Glidewell et al. 2001;Mill et al. 2001Mill et al. , 2004Restemeyer 2002;Tomlinson and Takaso 2002;Khan and Hill 2021). The prumnopityoid clade includes the remaining less explored taxa (e.g., Sahni and Mitra 1927;Khan et al. 2022) and presents little consensus in the resolution of internal relationships (Andruchow-Colombo et al. 2019a;Sudianto et al. 2019). ...

NMR imaging as a tool for noninvasive taxonomy: Comparison of female cones of two Podocarpaceae
  • Citing Article
  • April 2002

... The coupling constants obtained were consistent with those reported for 2-methyl-2-nitrosopropane (MNP), i.e. 14.8-14.9 G ( 14 N) and 2.1 G ( 1 H) (Vicente, Empis, Deighton, Glidewell, Goodman & Rowlands, 1998;Merkx et al., 2021), rather than with those for alkyl-PBN adducts, i.e. 14.7 G ( 14 N) and 3.26 G ( 1 H), found in fatty acid methyl esters oxidized in the presence of PBN (Vicente et al., 1998). Through ESR and ENDOR analyses, it has been found that MNP is a decomposition product of the highly unstable peroxyl-PBN spin adducts, whose 14 N and 1 H hyperfine splitting constants were 13.7 G and 2.0 G, respectively. ...

Use of EPR and ENDOR spectroscopy in conjunction with the spin trapping technique to study the high-temperature oxidative degradation of fatty acid methyl esters †
  • Citing Article
  • February 1998

Journal of the Chemical Society Perkin Transactions 2