• Fourier-transform Raman spectroscopic study of a Neolithic waterlogged wood assemblage

      Petrou, M.; Edwards, Howell G.M.; Janaway, Robert C.; Thompson, Gill B.; Wilson, Andrew S. (2009)
      The use of Fourier-transform Raman spectroscopy for characterising lignocellulosics has increased significantly over the last twenty years. Here, an FT-Raman spectroscopic study of changes in the chemistry of waterlogged archaeological wood of Pinus sp. and Quercus sp. from a prehistoric assemblage recovered from northern Greece is presented. FT-Raman spectral features of biodeteriorated wood were associated with the depletion of lignin and/or carbohydrate polymers at various stages of deterioration. Spectra from the archaeological wood are presented alongside spectra of sound wood of the same taxa. A comparison of the relative changes in intensities of spectral bands associated with lignin and carbohydrates resulting from decay clearly indicated extensive deterioration of both the softwood and hardwood samples and the carbohydrates appear to be more deteriorated than the lignin. The biodeterioration of the archaeological timbers followed a pattern of initial preferential loss of carbohydrates causing significant loss of cellulose and hemicellulose, followed by the degradation of lignin.
    • Förster Resonance Energy Transfer across interpolymer complexes of poly(acrylic acid) and poly(acrylamide)

      Swift, Thomas; Paul, N.; Swanson, L.; Katsikogianni, Maria G.; Rimmer, Stephen (2017-08-11)
      Interpolymer complexes of homopolymer macromolecules are often described as ‘laddered’ or ‘ribbon’ type structures. The proposition of the existence of these ladder structures seems to us not reasonable and here we examine this hypothesis. To address this we have used polymers enabled for Förster Energy Transfer (FRET). Chromophores bound to a macromolecular backbone can transfer energy across short distances via FRET. The close binding of poly(acrylamide) and poly(acrylic acid) interpolymer complex formation at low pH forms a structure compact enough for significant energy transfer to occur between different chains containing naphthalene and anthracene labels. In the context of the proposition that ladder polymers can form it was surprising that the distance between labels on the same polymer back-bone was equivalent regardless of whether the polymer was complexed or not. The data indicated that the bicomponent structure may be more compact than previously supposed: I.e. the complexes are not ladders composed of extended chains. This evidence suggests formation not of ordered ‘ladder’ systems but colloidal ‘co-globules’.
    • Förster resonance energy transfer confirms the bacterial-induced conformational transition in highly-branched poly(N-isopropyl acrylamide with vancomycin end groups on binding to Staphylococcus aureus

      Sarker, P.; Swindells, K.; Douglas, C.W.I.; MacNeil, S.; Rimmer, Stephen; Swanson, L. (2014)
      We describe a series of experiments designed to investigate the conformational transition that highly-branched polymers with ligands undergo when interacting with bacteria, a process that may provide a new sensing mechanism for bacterial detection. Fluorescent highly-branched poly(N-isopropyl acrylamide)s (HB-PNIPAM) were prepared by sequential self-condensing radical copolymerizations, using anthrylmethyl methacrylate (AMMA) and fluorescein-O-acrylate (FA) as fluorescent comonomers and 4-vinylbenzyl pyrrole carbodithioate as a branch forming monomer. Differences in reactivity necessitated to first copolymerize AMMA then react with FA in a separate sequential monomer feed step. Modifications of the chain ends produced vancomycin-functional derivatives (HB-PNIPAM-Van). The AMMA and FA labels allow probing of the conformational behaviour of the polymers in solution via Forster resonance energy transfer experiments. It was shown that interaction of this polymer's end groups with Staphylococcus aureus induced a macromolecular collapse. The data thus provide conclusive evidence for a conformational transition that is driven by binding to a bacterium.
    • Förster resonance energy transfer in fluorophore labeled poly(2-ethyl-2-oxazoline)s†

      Merckx, R.; Swift, Thomas; Rees, R.; Van Guyse, J.F.R.; Schoolaert, E.; De Clerck, K.; Thienpont, H.; Jerca, V.V. (Royal Society of Chemistry, 2020)
      Dye-functionalized polymers have been extensively studied to understand polymer chain dynamics, intra or inter-molecular association and conformational changes as well as in practical applications such as signal amplification in diagnostic tests and light-harvesting antennas. In this work, the Förster resonance energy transfer (FRET) of dye-functionalized poly(2-ethyl-2-oxazoline) (PEtOx) was studied to evaluate the effect of dye positioning and polymer chain length on the FRET efficiency. Therefore, both α (initiating terminus)- or ω (terminal chain end)-fluorophore single labeled and dual α,ω-fluorescent dye labeled PEtOx were prepared via cationic ring opening polymerization (CROP) using 1-(bromomethyl)pyrene as the initiator and/or 1-pyrenebutyric acid or coumarin 343 as the terminating agent, yielding well-defined PEtOx with high labeling efficiency (over 91%). Fluorescence studies revealed that intramolecular FRET is most efficient for heterotelechelic PEtOx containing both pyrene and coumarin 343 fluorophores as chain ends, as expected. A strong dependence of the energy transfer on the chain length was found for these dual labeled polymers. The polymers were tested in both dilute organic (chloroform) and aqueous media revealing a higher FRET efficiency in water due to the enhanced emissive properties of pyrene. The application of dual labeled polymers as fluorescent probes for temperature sensing was demonstrated based on the lower critical solution temperature behavior of the PEtOx. Furthermore, these polymers could be successfully processed into fibers and thin films. Importantly, the fluorescence properties were retained in the solid state without decreasing the FRET efficiency, thus opening future possibilities for application of these materials in solar cells and/or sensors.
    • Fragmentation of N-linked glycans with a matrix-assisted laser desorption/ionization ion trap time-of-flight mass spectrometer.

      Harvey, D.J.; Martin, R.L.; Jackson, K.A.; Sutton, Chris W. (Wiley, 2004)
      N-Linked glycans were ionized from several matrices with a Shimadzu-Biotech AXIMA-QIT matrix-assisted laser desorption/ionization quadrupole ion trap time-of-flight mass spectrometer. [M+Na]+ ions were produced from all matrices and were accompanied by varying amounts of in-source fragmentation products. The least fragmentation was produced by 2,5-dihydroxybenzoic acid and the most by -cyano-4-hydroxycinnamic acid and 6-aza-2-thiothymine. Sialic acid loss was extensive but could be prevented by formation of methyl esters. Fragmentation produced typical low-energy-type spectra dominated by ions formed by glycosidic cleavages. MSn spectra (n = 3 and 4) were used to probe the pathways leading to the major diagnostic ions. Thus, for example, an ion that was formed by loss of the core GlcNAc residues and the 3-antenna was confirmed as being formed by a B/Y rather than a C/Z mechanism. The proposed structures of several cross-ring cleavage ions were confirmed and it was shown that MS3 spectra could be obtained from as little as 10 fmol of glycan
    • Fragmentation of the Body: Comestibles, Compost or Customary Rite?

      Knüsel, Christopher J.; Outram, A.K. (2009-11-30)
      One of the most inimical ways to debase a people is to declare them cannibals - eaters of their own kind. The association between cannibalism and immorality, depravity, and base iniquity has contributed to the long-term interest in the behaviour. It has become a commonplace pejorative applied to exotic peoples, enemies, and strangers - sometimes and, more innocuously perhaps, to titillate fascination and, more sinisterly and more often, to dehumanise another group. Tuzin (1983, 62) characterises the Ilahita Arapesh's (of northeastern New Guinea) attitude towards the cannibalism of the downstream Sepik, "... as an amused, faintly condescending interest that is morally neutral in tone...'and that those who engage in such consumption are described as an 'another kind of man'. The apparent relativism of this statement, although lacking in obvious contempt or fear, provides the basis upon which difference could be accentuated to justify actions at another time or under different circumstances. The use of the term 'cannibalism' among both Europeans and non-Europeans (see Strathern 1982, Rumsey 1999) to make a people less than human - with real social and political consequences for those so-labeled - prompted Arens (1979) to deny that the behaviour had ever been practised. Others have argued that it did occur upon occasion in a number of circumstances and for a variety of reasons.
    • Frailty and the Microbiome

      Meehan, Conor J.; Langille, M.G.I.; Beiko, R.G. (Karger, 2015)
      From the moment of birth, the human body plays host to a rich diversity of microbes. Body sites such as the skin, the gut and the mouth support communities of microorganisms (collectively known as the microbiome) that are both numerous and diverse. As our understanding of the microbiome advances, it is evident that these microbial populations participate in a multitude of symbiotic associations with us. The disruption of these associations can lead to a range of diseases beyond mere pathogenesis as microbial nutrition, signaling, and immune defense break down. It is known that changes in microbial composition occur as the human host ages and that diet and living conditions influence the microbiome of older individuals. However, the link between the microbiome and frailty is as yet mostly unexplored. Although the microbiome is likely to influence health factors that contribute to frailty, further work is needed to determine whether overall microbial signatures of frailty exist and, if so, what the diagnostic and therapeutic utility of these signatures might be.
    • Frequent p16-independent inactivation of p14ARF in human melanoma

      Freedberg, D.E.; Rigas, S.H.; Russak, J.; Gai, W.; Kaplow, M.; Osman, I.; Turner, F.; Randerson-Moor, J.A.; Houghton, A.; Busam, K.; et al. (2008)
      BACKGROUND: The tumor suppressors p14(ARF) (ARF) and p16(INK4A) (p16) are encoded by overlapping reading frames at the CDKN2A/INK4A locus on chromosome 9p21. In human melanoma, the accumulated evidence has suggested that the predominant tumor suppressor at 9p21 is p16, not ARF. However, recent observations from melanoma-prone families and murine melanoma models suggest a p16-independent tumor suppressor role for ARF. We analyzed a group of melanoma metastases and cell lines to investigate directly whether somatic alterations to the ARF gene support its role as a p16-independent tumor suppressor in human melanoma, assuming that two alterations (genetic and/or epigenetic) would be required to inactivate a gene. METHODS: We examined the p16/ARF locus in 60 melanoma metastases from 58 patients and in 9 human melanoma cell lines using multiplex ligation-dependent probe amplification and multiplex polymerase chain reaction (PCR) to detect deletions, methylation-specific PCR to detect promoter methylation, direct sequencing to detect mutations affecting ARF and p16, and, in a subset of 20 tumors, immunohistochemistry to determine the effect of these alterations on p16 protein expression. All statistical tests were two-sided. RESULTS: We observed two or more alterations to the ARF gene in 26/60 (43%) metastases. The p16 gene sustained two or more alterations in 13/60 (22%) metastases (P = .03). Inactivation of ARF in the presence of wild-type p16 was seen in 18/60 (30%) metastases. CONCLUSION: Genetic and epigenetic analyses of the human 9p21 locus indicate that modifications of ARF occur independently of p16 inactivation in human melanoma and suggest that ARF is more frequently inactivated than p16.
    • From dates to demography in later prehistoric Ireland? Experimental approaches to the meta-analysis of large 14C data-sets

      Armit, Ian; Swindles, Graeme T.; Becker, Katharina (2013)
      We present a series of iterative methods to examine the problems associated with summed probability functions (SPFs) based on archaeological radiocarbon data. As a case study we use an SPF generated from a substantial radiocarbon data-set from the Irish Later Bronze and Iron Ages. We use simple numerical methods to show that real patterns can be deciphered from SPFs that can be used to trace and evaluate patterns of change. However, our results suggest that SPFs should not be used as a simple index of past human activity.
    • From Macro to Micro: Multi-scalar Digital Approaches at the Sculptor’s Cave, North-East Scotland

      Büster, Lindsey; Armit, Ian; Evans, Adrian A.; Sparrow, Thomas; Kershaw, Rachael; Wilson, Andrew S. (2019-02-08)
      Excavations in the 1920s and 1970s at the Sculptor’s Cave, North-East Scotland, revealed that the site was used for mortuary rituals during the Late Bronze Age (c. 1100–800 BC) and Roman Iron Age (late first to fourth centuries AD), whilst a series of Pictish symbols carved into its entrance walls suggest that the cave’s importance continued into the Early Medieval Period. A new programme of analysis has utilised advanced 3D digital documentation and 3D metrology (specifically, 3D laser scanning) to enable this inaccessible site to be appreciated by wider audiences and analysed remotely. Detailed in situ recording of the Pictish symbols was undertaken using macro-level structured light scanning and the high-fidelity digital models blended with terrestrial laser scan data of the cave interior to show the location and detail of the carvings. This chapter examines the value of emerging digital approaches in the analysis, presentation and management of the Sculptor’s Cave, from the elucidation of additional carved details and the monitoring of surface degradation, to the dissemination of this difficult-to-access site to the wider public via online platforms.
    • From Picts to Parish: Stable isotope evidence of dietary change at medieval Portmahomack, Scotland

      Curtis-Summers, Shirley; Pearson, J.A.; Lamb, A.L. (2020-06)
      In this study, period-specific dietary trends, along with socio-economic and religious influences on foods consumed by Pictish and medieval inhabitants from Portmahomack are investigated. Bone collagen from human adults (n = 137) and fauna (n = 71) were analysed for stable carbon and nitrogen isotope ratios to enable dietary reconstructions of the whole adult skeletal assemblage. Adult mean δ13C and δ15N values from all periods (6th to 17th century) were −19.5‰ ± 1.3‰ and 13.3‰ ± 1.7‰ respectively. A diachronic change in diet between early medieval Pictish lay and monastic communities (periods 1–3) and the later medieval parish layfolk (periods 4–5) was found that suggests changing socio-economic and religious influences, along with age and gender differences in diet that reflect possible divisions in labour and status. Faunal data also reflected a diachronic change in diet, most likely related to a change in animal husbandry practices over time. This is the first large-scale study on the Portmahomack assemblage and presents new isotope data to provide a more comprehensive insight into Pictish and medieval subsistence patterns, along with evidence of how religious and social foci may influence diet over time. Such comprehensive investigations can only be adopted by analysing the whole skeletal assemblage, providing robust faunal baselines and inter- and intra-site comparisons. Most importantly, this significant new evidence fundamentally changes our knowledge of diet and subsistence in medieval Scotland and the potential influences therein.
    • From Plastered Skulls to Palliative Care: What the Past Can Teach Us About Dealing with Death

      Büster, Lindsey S.; Croucher, Karina T.; Dayes, Jennifer E.; Green, Laura I.; Faull, C. (2018)
      Modern, advanced healthcare detects and monitors long-term and life-limiting illness more comprehensively than ever before. However, death is now often considered medical failure, and is a virtually taboo topic of conversation in daily life. At a time when the societal relevance of archaeology is under scrutiny more than ever before, the AHRC-funded Continuing Bonds Project – a collaboration between archaeology and palliative care – explores the potential of the past to promote discussion. Not only does archaeology illuminate the diversity of practice surrounding death, the past provides a safe, distanced platform for considering death, dying and bereavement today. Through archaeological and ethnographic case studies, health and social care professionals and students consider topics such as place, choice and identity, in both personal and professional life. This article examines participant responses to a variety of archaeological material and presents post-workshop reflections which demonstrate the success of archaeology in opening up conversations and increasing confidence in discussing this most enduring and problematic of life events.
    • From Susa to Anuradhapura: Reconstructing aspects of trade and exchange in bitumen-coated ceramic vessels between Iran and Sri Lanka from the Third to the Ninth Centuries AD.

      Stern, Ben; Connan, J.; Blakelock, Eleanor S.; Jackman, R.; Coningham, Robin A.E.; Heron, Carl P. (2008)
      In contrast with artefactual studies of long-distance trade and exchange in South Asia during the Prehistoric and Early Historic periods (Ardika et al . 1993; Gogte 1997; Krishnan and Coningham 1997; Tomber 2000; Gupta et al . 2001; Ford et al . 2005), few scientifically orientated analyses have focused on artefacts from the region¿s Historic period. During excavations at the ancient city of Anuradhapura, Sri Lanka, a number of buff ware ceramics with a putative organic coating on the interior were recovered (Coningham 2006). Dated stylistically to between the third and ninth centuries AD , analysis of the coatings using gas chromatography¿mass spectrometry (GC¿MS) and stable isotope analysis (carbon and deuterium) confirmed that the coatings are bitumen¿an organic product associated with petroleum deposits. There are no known bitumen sources in Sri Lanka, and biomarker distributions and isotopic signatures suggest that the majority of the samples appear to have come from a single bitumen source near Susa in Iran. The relationship between the bitumen coatings and the vessels is discussed, and it is suggested that the coatings were used to seal permeable ceramic containers to allow them to transport liquid commodities. This study enhances our knowledge of networks of trade and exchange between Sri Lanka and western Asia during Historic times.
    • From ‘fixed dose combinations’ to ‘a dynamic dose combiner’: 3D printed bi-layer antihypertensive tablets

      Sadia, M.; Isreb, Abdullah; Abbadi, I.; Isreb, Mohammad; Aziz, D.; Selo, A.; Timmins, P.; Alhnan, M.A. (2018-10)
      There is an increased evidence for treating hypertension by a combination of two or more drugs. Increasing the number of daily intake of tablets has been reported to negatively affect the compliance of patients. Therefore, numerous fixed dose combinations (FDCs) have been introduced to the market. However, the inherent rigid nature of FDCs does not allow the titration of the dose of each single component for an individual patient's needs. In this work, flexible dose combinations of two anti-hypertensive drugs in a single bilayer tablet with a range of doses were fabricated using dual fused deposition modelling (FDM) 3D printer. Enalapril maleate (EM) and hydrochlorothiazide (HCT) loaded filaments were produced via hot-melt extrusion (HME). Computer software was utilised to design sets of oval bi-layer tablets of individualised doses. Thermal analysis and x-ray diffractometer (XRD) indicated that HCT remained crystalline in the polymeric matrix whilst EM appeared to be in an amorphous form. The interaction between anionic EM and cationic methacrylate polymer may have contributed to a drop in the glass transition temperature (Tg) of the filament and obviated the need for a plasticiser. Across all tablet sets, the methacrylate polymeric matrix provided immediate drug release profiles. This dynamic dosing system maintained the advantages of FDCs while providing a superior flexibility of dosing range, hence offering an optimal clinical solution to hypertension therapy in a patient-centric healthcare service.
    • FT-Raman Spectroscopic Study of Calcium-Rich and Magnesium-Rich Carbonate Minerals

      Munshi, Tasnim; Edwards, Howell G.M.; Jenlicka, J.; Jorge Villar, Susana E. (2005)
      Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.
    • FT-Raman spectroscopy of the Candelaria and Pyxine lichen species: A new molecular structural study

      Fernandes, R.F.; Ferreira, G.R.; Spielmann, A.A.; Edwards, Howell G.M.; de Oliveira, L.F.C. (2015-12)
      In this work the chemistry of the lichens Candelaria fibrosa and Pyxine coccifera have been investigated for the first time using FT-Raman spectroscopy with the help of quantum mechanical DFT calculations to support spectral band assignments. The non-destructive spectral vibrational analysis provided evidence for the presence of pulvinic acid derivatives and conjugated polyenes, which probably belong to a carotenoid with characteristic signatures at ca. 1003, 1158 and 1525 cm−1 assigned respectively to δ(C–CH3), ν(C–C) and ν(Cdouble bond; length as m-dashC) modes. The identification of features arising from chiodectonic acid in the Pyxine species and calycin and pulvinic dilactone pigments in C. fibrosa were assisted by the quantum mechanical DFT calculations. Raman spectroscopy can provide important spectroscopic data for the identification of the biomarker spectral signatures nondestructively for these lichen pigments without the need for chemical extraction processes.
    • A fully functional proopiomelanocortin/melanocortin-1 receptor system regulates the differentiation of human scalp hair follicle melanocytes.

      Kauser, Sobia; Thody, Anthony J.; Schallreuter, Karin U.; Gummer, C.L.; Tobin, Desmond J. (2005)
      The proopiomelanocortin (POMC)-derived peptides, ACTH and alpha-MSH, are the principal mediators of human skin pigmentation via their action at the melanocortin-1 receptor (MC-1R). Recent data have demonstrated the existence of a functionally active beta-endorphin/mu-opiate receptor system in both epidermal and hair follicle melanocytes, whereby beta-endorphin can regulate melanogenesis, dendricity, and proliferation in these cells. However, a role for ACTH and alpha-MSH in the regulation of the human follicular pigmentary unit has not been determined. This study was designed to examine the involvement of ACTH and the alpha-MSH/MC-1R system in human follicular melanocyte biology. To address this question we employed RT-PCR and immunohisto/cytochemistry, and a functional role for these POMC peptides was assessed in follicular melanocyte cultures. Human scalp hair follicle melanocytes synthesized and processed POMC. ACTH and alpha-MSH in association with their processing enzymes and MC-1R are expressed in human follicular melanocytes at the message level in vitro and at the protein level both in situ and in vitro. The expression of the POMC/MC-1R receptor system was confined only to subpopulations of poorly and moderately differentiated melanocytes. In addition, functional studies revealed that ACTH and alpha-MSH are able to promote follicular melanocyte differentiation by up-regulating melanogenesis, dendricity, and proliferation in less differentiated melanocyte subpopulations. Thus, these findings suggest a role for these POMC peptides in regulating human hair follicle melanocyte differentiation.
    • Function and Antagonism of beta3 integrins in the development of cancer therapy

      Sheldrake, Helen M.; Patterson, Laurence H. (2009-06)
      The integrin family of cell surface receptors integrates cell-extracellular matrix interactions with the cell cytoskeleton and signalling across the cell membrane, resulting in an important role in cell adhesion, mobility and migration, proliferation, and survival. Changes in the number and identity of integrin receptors are common in cancer cells resulting in alteration of the ability of malignant cells to interact with the extracellular matrix, and promoting migration as well as facilitating survival outside the tumour normal environment. Beta3 integrins are potentially involved in every step of the metastatic process and expression of both alphaIIbbeta3 and alphaVbeta3 is correlated with metastatic ability of tumour cells. The recognition of the RGD binding motif common to the disintegrins and natural integrin ligands such as fibrinogen allowed the development of small molecule beta3 integrin antagonists, progressing from linear peptides containing the RGD sequence to cyclic peptides with well-defined conformation, and hence to small molecule peptidomimetics with improved pharmacological properties. In this review, we summarize the role of the beta3-subfamily of integrins when expressed in normal and tumour tissue, the development of small-molecule antagonists of beta3 integrins and their potential anti-cancer applications
    • Functional evidence for cone-specific connectivity in the human retina

      Whitaker, David J.; McGraw, Paul V.; McKeefry, Declan J.; Vakrou, Chara (2009-06-09)
      Physiological studies of colour vision have not yet resolved the controversial issue of how chromatic opponency is constructed at a neuronal level. Two competing theories, the cone-selective hypothesis and the random-wiring hypothesis, are currently equivocal to the architecture of the primate retina. In central vision, both schemes are capable of producing colour opponency due to the fact that receptive field centres receive input from a single bipolar cell ¿ the so called `private line arrangement¿. However, in peripheral vision this single-cone input to the receptive field centre is lost, so that any random cone connectivity would result in a predictable reduction in the quality of colour vision. Behavioural studies thus far have indeed suggested a selective loss of chromatic sensitivity in peripheral vision. We investigated chromatic sensitivity as a function of eccentricity for the cardinal chromatic (L/M and S/(L + M)) and achromatic (L + M) pathways, adopting stimulus size as the critical variable. Results show that performance can be equated across the visual field simply by a change of scale (size). In other words, there exists no qualitative loss of chromatic sensitivity across the visual field. Critically, however, the quantitative nature of size dependency for each of the cardinal chromatic and achromatic mechanisms is very specific, reinforcing their independence in terms of anatomy and genetics. Our data provide clear evidence for a physiological model of primate colour vision that retains chromatic quality in peripheral vision, thus supporting the cone-selective hypothesis.
    • Functional Redundancy of two nucleoside transporters of the ENT family (CeENT1, CeENT2) required for development of Caenorhabditis elegans.

      Appleford, P.J.; Griffiths, M; Yao, S.Y.; Ng, A.M.; Chomey, E.G.; Isaac, R.E.; Coates, David; Hope, I.A.; Cass, C.E.; Young, J.D.; et al. (2009-11-25)
      The genome of Caenorhabditis elegans encodes multiple homologues of the two major families of mammalian equilibrative and concentrative nucleoside transporters. As part of a programme aimed at understanding the biological rationale underlying the multiplicity of eukaryote nucleoside transporters, we have now demonstrated that the nematode genes ZK809.4 (ent-1) and K09A9.3 (ent-2) encode equilibrative transporters, which we designate CeENT1 and CeENT2 respectively. These transporters resemble their human counterparts hENT1 and hENT2 in exhibiting similar broad permeant specificities for nucleosides, while differing in their permeant selectivities for nucleobases. They are insensitive to the classic inhibitors of mammalian nucleoside transport, nitrobenzylthioinosine, dilazep and draflazine, but are inhibited by the vasoactive drug dipyridamole. Use of green fluorescent protein reporter constructs indicated that the transporters are present in a limited number of locations in the adult, including intestine and pharynx. Their potential roles in these tissues were explored by using RNA interference to disrupt gene expression. Although disruption of ent-1 or ent-2 expression alone had no effect, simultaneous disruption of both genes yielded pronounced developmental defects involving the intestine and vulva.