School of Science

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Research at AUT's School of Science is focused on key scientific issues with regional and global significance. The common theme connecting all research areas is sustainability – in the broadest sense as it relates to environmental and human health. Our research is closely allied to teaching and learning opportunities at undergraduate and postgraduate level within the school. Research is organised in three thematic areas:

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New nematode species and genera (Chromadorida, Microlaimidae) from the deep sea of the eastern tropical South Pacific
(Natural History Museum Vienna, 1999) Bussau, C; Vopel, K
Six new nematode species are described from the sediment of a manganese nodule area of the abyssal eastern South Pacific: Aponema nympha sp.n., Caligocanna mirabilis gen.n. sp.n., Microlaimus discolensis sp.n., M. clancularius sp.n., M. porosus sp.n., and Bathynox clavata gen.n. sp.n.. The new genera Caligocanna and Bathynox are considered to belong to the Microlaimidae MICOLETZKY, 1922. The genus Caligocanna gen.n. differs from all other genera of the family Microlaimidae in combining the following characters: The six cephalic setae of the second circlet longer than the four cephalic setae of the third circlet. Annulated cuticle; annules with numerous longitudinal bars. Monospiral amphids turn ventrally. The genus Bathynox gen.n. differs from all other genera of the family Microlaimidae in having projecting, club-shaped corpora gelata and somatic setae positioned on peduncles.
Microclimate of the brown alga Feldmannia caespitula interstitium under zero-flow conditions
(Inter Research, 2001) Pohn, M; Vopel, K; Grunberger, E; Ott, J
The microclimate of the brown alga Feldmannia caespitula (J. Agardh) Knoepffler-Peguy interstitium was studied using microelectrode techniques. Zero water flow and irradiances of 170 and 1500 mu mol photons m(-2) s(-1) cause steep O-2 gradients peaking 3 to 4 mm below the outer surface of the tufts at 310 and 506% atmospheric saturation, respectively. The mean fluxes of O-2 from the interstitium to the surrounding bulk water were 87 +/- 21 and 262 +/- 68 nmol cm(-2) h(-1) at low and high quantum flux density. Except for the outer 2 to 4 mm thick margin, the alga interstitium became anoxic within 52 min after abrupt darkening. The rate of dark oxygen uptake was 52 +/- 5 nmol cm(-2) h(-1). The tufts were populated by 9 metazoan taxa: nematodes, harpacticoid copepods, ostracods, gastropods, bivalves, polychaetes, amphipods, isopods and halacarids. Our results suggest that the interstitium of fine-textured algal thalli is a microhabitat of variable water chemistry with temporary anoxia and hyperoxia in an otherwise relatively stable water column. Although the tufts are attractive for meiofauna by providing food and protection from currents and predators, rapid fluctuations in oxygen concentration probably cue temporal emigration of the algal infauna.
Self-organising Maps to Study the Effects of Urbanisation at Long Bay in New Zealand
(Knowledge Engineering Lab, the University of Otago, 2001) Shanmuganathan, S; Sallis, P; Buckeridge, JS
Biologically inspired Artificial Neural Network (ANN) modelling methods provide a means of problem solving that incorporates heuristics with conventional algorithmic processing Over the last few decades, nell' techniques for neuron relationship modelling and network architecture algorithms have been introduced to solve a ll'ide range of problems across many fields. This paper looks into the aspects of using SOMs to a biological example to permit understanding of a complex environmental process. The preliminmy research results to study the effects of urbanisation on marine life at the Long Bay-Okura Marine Reserve, situated in northern Nell' Zealand is discussed in detail. This was the count1y 's first urban, marine resen1e to be established (1995), and resulted from groll'ing concern of environmental groups and general public of the area. Since then many institutions have conducted research to find the cause for the observed environmental change. All these data sets are fused and analysed collectively to study the patterns in them. The use of SOMs to industrial process monitoring has been ve1y successful in many areas and is applied here to study the process dynamics in environmental process modelling with SOM trajectories. The analyses show the relationships found in the data sets from different sources in easily perceivable formats without having to model the complex physical process.
Ciliate-generated advective seawater transport supplies chemoautotrophic ectosymbionts
(Inter-Research, 2001-01-26) Vopel, K; Pohn, M; Sorgo, A; Ott, J
Variations of [O2] and [H2S] in seawater surrounding laboratory reared sessile ciliates with ectosymbiotic chemoautotrophic bacteria were studied at high spatial and temporal resolutions using amperometric microsensors. We show how suspension feeding by the colonial Zoothamnium niveum and the solitary Vorticella sp. in the chemocline (O2/H2S-interface) of near-natural and artificial H2S-releasing substrates generates the physico-chemical microenvironment for the ectobiotic bacteria. Continuous recordings revealed a steep increase of [O2] and decrease of [H2S] in the proximal region of Z. niveum colonies during rapid stalk contraction. Hydrogen sulphide concentrations 2.5 mm above the substrate (upper end of the fully extended colony) increased when the contracted colony extended, followed by a decrease after the colony attained the fully upright position. Multiple contractions without complete extension successively transported sulphidic seawater upwards. The solitary Vorticella sp. maintained high ambient [O2] and low [H2S] 350 μm above the H2S-releasing membrane by generating a vertical flow field that drew seawater from above toward the ciliate. Oxygen concentration at the proximal part of Vorticella sp. did not increase during contraction, whereas during slow extension deoxygenated seawater was transported upwards and rapidly mixed with the surrounding oxygenated seawater when the ciliate started to beat its cilia. In both species rapid stalk contraction and subsequent slow extension enhanced the mixing of oxygenated and deoxygenated, H2S-containing seawater; the feeding currents (toroidal vortices) drew the surrounding seawater within reach of the zooid’s external surface at high speed. It is suggested that this advective fluid transport supplies the ectobiotic bacteria with O2 and H2S simultaneously. The high fluid velocity may cause a decrease in cell boundary layer thickness, thereby enhancing rates of nutrient uptake by the ectobiotic bacteria.
Flow microenvironment of two marine peritrich ciliates with ectobiotic chemoautotrophic bacteria
(Inter-Research, 2002-09-03) Vopel, K; Reick, CH; Arlt, G; Pohn, M; Ott, JA
The flow microenvironment of 2 marine peritrich ciliates, Vorticella sp. and Zoothamnium niveum, with ectobiotic sulfur bacteria was studied with frame-by-frame analyses of video sequences and a microsensor for fluid velocity. Both species populate the chemocline above H2Sreleasing mangrove peat. Vorticella sp. moves the surrounding seawater up to a horizontal and vertical distance of at least 400 μm with a maximum flow velocity of 18 mm s–1 close to its peristomial edge. The feather-shaped colonies of Z. niveum generate a unidirectional flow of seawater passing the colony perpendicular to the stalk; the convex side of the feather faces upstream. The flow velocity increased exponentially towards the colony, up to 11 mm s–1 at a distance of 100 μm. Contraction of the stalk forces the zooids of Vorticella sp. and Z. niveum towards the substrate at a high velocity of 71 and 520 mm s–1, respectively. During contraction of Vorticella sp., only little seawater is dragged along towards the surface to which the ciliates are attached whereas the contraction of Z. niveum resulted in a clear increase in the velocity of the seawater both surrounding the colony and above the substrate. Extension of the species proceeds 700 to 1000 times more slowly than contraction, and the surrounding seawater sticks to the cells and therefore is dragged along. The measurements given here support our earlier data indicating the importance of the feeding current for the bacteria-ciliate association, i.e. the cilia beat drives H2S- and O2-containing seawater toward the zooid at high velocity and thus, supports the growth of the ectobiotic sulfide-oxidizing bacteria. Rapid movement, shrinkage (Vorticella sp.) and bunching (Z. niveum) of the zooids during stalk contraction apparently cause sufficient shear stress to abrade ectobiotic bacteria that, once suspended, could enter the feeding currents.
Effect of the brittle star Amphiura filiformis (Amphiuridae, Echinodermata) on oxygen flux into the sediment
(American Society of Limnology and Oceanography (ASLO) - Blue Policies in RoMEO, 2003-09-01) Vopel, K; Thistle, D; Rosenberg, R
O-2 plays a key role in early sedimentary diagenetic processes, but the effect of most macrofaunal species on the pathways and rates of supply of O-2 into the seabed are not well known. We investigated the effect of the ophiuroid Amphiura filiformis, one of the dominant macrobenthic species on soft bottoms in the northeast Atlantic, at depths of similar to15-100 m, in a laboratory environment. We determined how the presence of the ophiuroid changed the total O-2 uptake of macrofauna-free sediment by combining measurements from a microcosm approach and an approach that uses microelectrodes and a flushed aquarium. We suggest that natural populations of A. filiformis can account for 80% of the total flux of O-2 into the soft bottom. At least 67% of this portion is due to the diffusion of O-2 across additional sediment-water interfaces excavated by the brittle star.
The timing of benthic copepod emergence
(American Society of Limnology and Oceanography (ASLO), 2004-05-01) Teasdale, M; Vopel, K; Thistle, D
We investigated emergence of marine benthic harpacticoid and cyclopoid copepods from subtidal sediment into the bottom water. Previous studies that used traps in the field found that copepods emerged from the sediment within 2 h of dusk. We examined emergence in 20-min sampling periods over 13 h from 1200 to 0100 h in a laboratory flume under conditions of constant flow speed. The light intensity was adjusted to field conditions every 20 min. We observed a peak in emergence during the 20-min sampling period after the onset of darkness, greatly increasing the accuracy with which the timing of emergence is known. This result will help to set the stage for studies of emergence cues.
More than just a crab hole
(NIWA, 2005) Vopel, K; Hancock, N
Mangrove trees trap fine sediment brought in by rivers and the tide. This sediment is the home of various bacteria, algae, protozoa, and invertebrates (such as marine worms) that cope well with the challenges of an intertidal mudflat, including the risk of desiccation, overheating, oxygen deficiency, and regular exposure to air and hydrogen sulphide. These organisms modify their environment and interact with other organisms by exchanging materials in the form of food, waste material, and respiratory gases. However, some larger species are especially important in the ecosystem. Going beyond these relatively straightforward transactions, they alter the nature of the sediment in ways that affect organisms other than their direct competitors, predators, or prey. Ecologists call such species 'ecosystem engineers' because they create new habitats and change the availability of nutrients to other species.
Breathing sediments: microbes, waves, and hidden animal pumps
(NIWA, 2005) Funnell, G; Vopel, K
Kay Vopel and Greig Funnell look into the mechanisms and creatures that help maintain the seabed’s life-support system. Aquatic sediment provides an important ecosystem service: the decomposition of organic matter and the associated regeneration of nutrients for algae and plants. In coastal marine ecosystems, more than half of the nutrients available for primary production in the water column and at the sediment surface can be supplied by the sedimentary processes of aerobic and anerobic decomposition. The most important (and abundant) players in this service are aerobic and anaerobic bacteria, which transform organic into inorganic matter using oxidants such as oxygen and nitrate. 49710 Fluid-dynamic animal pumps on the sediment surface of Mahurangi Harbour. (Click for enlargement and details)(Photos: K. Vopel) 49711 Kay Vopel uses a microelectrode mounted onto a micromanipulator to measure oxygen concentrations in the sediment immediately surrounding a buried echinoderm. (Photo: G. Funnell) To supply the bacteria with oxidants, the sediment breathes, just like we do to supply our cells. When we breathe, we transport oxygen into our lungs and from there into the bloodstream by air flow and molecular diffusion. We draw our diaphragm down to inhale air and up to exhale. This maintains an oxygen concentration in the alveoli of our lungs that is sufficiently high to let oxygen molecules diffuse from the alveoli into our blood. A similar principle applies to aquatic sediment.
Wave-induced H2S flux sustains a chemoautotrophic symbiosis
(American Society of Limnology and Oceanography (ASLO), 2005-01-01) Vopel, K; Thistle, D; Ott, J; Bright, M; Roy, H
Symbioses involving sulfur-oxidizing bacteria and invertebrate hosts require a source of reduced sulfur, a source of O-2, and transport mechanisms that ensure them a supply of both. We investigated these mechanisms using the symbiosis between the sessile ciliate Zoothamnium niveum (Hemprich and Ehrenberg 1831) and bacteria living on its surface. The stalked colonies of Z niveum grow on peat walls around the openings of centimeter-scale conduits created when mangrove rootlets decompose. Using in situ, time-series measurements with fast-responding amper-ometric microelectrodes, we found that the conduits were charged with H2S by diffusion from the decaying rootlets during periods of low boundary-layer flow speed. During these times, the feeding current of the zooids transported oxygenated seawater from outside the peat wall toward the ectobiotic bacteria. During periods of high flow speed, H2S-rich seawater from the conduits was drawn along the colonies and over the bacteria. We conclude that this symbiosis exploits a combination of two transport mechanisms: (1) venting of H2S-rich seawater due to pulsating boundary-layer current over ciliate groups and (2) the continuous and rapid feeding current generated by the host's cilia. This discovery raises the possibility that other systems in which pockets of decay are exposed to pulsating flow could support similar symbioses.
NIWA news: going under ice to measure microbial mats
(NIWA, 2006) Vopel, K
The Dry Valley region of Southern Victoria Land, the largest icefree region of Antarctica, is one of the coldest and driest deserts in the world. There are numerous meltwater lakes in this region thanks to two regional features, the Transantarctic Mountain Range that blocks the flow of ice from the polar plateau and eliminates precipitation, and the very low mean air temperature (–15 to –30 ºC) that provides perennial ice cover, 3–6 m thick, to the lakes. Scientists have always been interested in the bacteria and microscopic algae inhabiting the lakes: they may offer insights into where and how life originated on earth, and where evidence of life – past or present – might occur on other planets on our solar system.
Deposition of terrigenous sediment on subtidal marine macirobenthos: response of two contrasting community types
(Inter-Research, 2006-01-24) Lohrer, AM; Thrush, SF; Lundquist, CJ; Vopel, K; Hewitt, JE; Nicholls, PE
Changes in patterns of land-use associated with human population growth throughout the world have altered the regime of terrigenous material export from catchments to rivers and, subsequently, to estuarine and marine communities. Although terrigenous sediment is now widely recognised as a disturbance agent in estuarine and marine communities, experimental studies on its impacts in subtidal habitats are rare. Terrigenous deposits in the intertidal zone de-water at low tide and are subjected to erosion by waves during emersion, so experimental results in spatially widespread subtidal habitats where these processes are muted may differ substantially. We deposited terrigenous sediment into replicate experimental plots at 6 m depth at 2 subtidal sites, creating 3 treatment levels (magnitudes of terrigenous material addition) inside and outside a small harbour in northern New Zealand. We tracked the persistence of the terrigenous deposits (3 and 7 mm thickness) over time and sampled macrobenthic communities at both sites on Days 7, 14 and 30, to compare and contrast their responses relative to controls. The diverse coarse sand community outside the harbour (Site MI) was more sensitive to terrigenous materials than that which lived in muddier sediments inside the harbour (Site TK), as indicated by multivariate and univariate analyses: both the 3 and 7 mm treatments caused significant change at Site MI, whereas only the more severe 7 mm treatment caused significant change at Site TK. The terrigenous sediments we added matched the grain size of Site TK sediments better, and macrobenthic animals living in turbid tidal estuaries are probably better conditioned to cope with high suspended sediment concentrations and sediment deposition rates. However, beyond a critical threshold, terrigenous sediment had a negative influence on communities at both sites, and they had not recovered by the time the experiment was terminated 30 d later.
Photosynthetic performance of benthic microbial mats in Lake Hoare, Antarctica
(American Society of Limnology and Oceanography (ASLO), 2006-07-01) Vopel, K; Hawes, I
We measured in situ photosynthesis of benthic microbial mats at various depths in Lake Hoare, a permanently ice-covered lake of the McMurdo Dry Valleys, Antarctica, using oxygen (02) microelectrodes. We further investigated the vertical distribution and activity of pigments in the microbial mats using an imaging pulse-amplitude-modulated fluorometer. Microbial mats to at least 16.6-m water depth are net producers Of 02 during the summer period. Net 02 production ranges from 100-500 mu mol m(-2) h(-1) at incident downwelling irradiances of photosynthetically active radiation (PAR) of 1.0-4.6 mu mol quanta m(-2) s(-1). Photosynthesis of mat-forming cyanobacteria and diatoms occurs at all lake depths at or close to maximum efficiency. We measured absorption by the pigment arrays at a single water depth and, by assuming that absorption is water-depth invariant, we estimated an area-specific maximum community quantum yield of 0.073 mol carbon per mol photons. A community compensation irradiance of 0.1 mu mol quanta m(-2) s(-1) was estimated, reflecting extreme shade acclimation. These results confirm estimates previously derived from laboratory gas-exchange measurements and imply that even minor changes in the intensity of the incident downwelling irradiance of PAR caused by, for example, changes in the transparency of the ice cover or the optical properties of the water column can significantly alter rates of benthic carbon fixation. In situ measurements were confined to mats with flat surfaces. Laboratory measurements at the surface of mats with pinnacled surfaces revealed a complex small-scale chemical structure at the mat-water interface.
Colourful seafloor
(National Institute of Water and Atmospheric Research Ltd (NIWA), 2007) Vopel, K; Giles, H; Zeldis, J
Kay Vopel, Hilke Giles,, and John Zeldis have combined three existing tools to come up with a new way of assessing change in coastal ecosystems. Sediments in coastal ecosystems have the job of breaking down organic matter. In a complex system of microbial activities and chemical reactions, organic matter is transformed to inorganic forms through a variety of pathways. Some of these paths return dissolved nutrients for the growth of algae living on the sediment or in the water; others produce ‘unwanted’ gases, such as the odorous hydrogen sulphide and methane. Bacteria play the most important part in the breakdown of organic matter but other organisms, such as worms, crustaceans, and larger bottom-dwelling creatures, also have important roles.
Effects of spatangoid heart urchins on O-2 supply into coastal sediment
(Inter-Research, 2007-03-21) Vopel, K; Vopel, A; Thistle, D; Hancock, N
Spatangoid heart urchins are key bioturbators in the marine environment. They pump seawater from the sediment surface around their tests and, at the same time, constantly displace the surrounding sediment. To improve our understanding of the effects of this activity on the oxygenation of coastal sediment, we studied for the first time in situ [O-2] around Echinocardium cordatum at sub-millimeter resolution under different hydraulic conditions. In the laboratory, we investigated the effects of E. cordatum on pore-water pH and sediment apparent diffusivity. Individuals advancing 1 to 3 cm h(-1) through the upper 4 cm of the sediment displaced a greater volume of seawater than sediment per unit time. The O-2 uptake of the sediment surrounding E. cordatum was at least twice the respiration of the echinoids. Besides creating additional sediment contact with oxygenated seawater, E. cordatum affected the Supply of O-2 to the sediment by altering photosynthetic O-2 production at the sediment surface, and increasing the exchange area of the sediment-seawater interface and apparent diffusivity of the uppermost sediment layer. After the passage of an individual, pore-water [O-2] profiles indicative of benthic photosynthesis recovered rapidly from the disturbance, but the pH of deeper pore water was altered. In situ, time series measurements of [O-2] and hydrostatic pressure indicated that wind waves can increase the transport of O-2 across both the sediment-seawater interface and the interface between the seawater surrounding E. cordatum and the adjacent sediment.
New insight on sediment processes
(National Institute of Water & Atmospheric Research (NIWA), 2007-11-15) Vopel, K
Bringing the harbour back to life. Postgraduate student Peter Wilson (left) and Dr Kay Vopel measuring microprofiles. (Photo: John Zeldis, NIWA) Coastal sediment acts as a biogeochemical reactor, breaking down organic matter through microbial activity and chemical processes, and releasing nutrients. Understanding the functioning of this reactor is key to predicting the effects of human activities, such as wastewater discharge, on coastal ecosystems. NIWA has developed a new tool to assess sediment functioning using a combination of two high-resolution measuring techniques and a numerical model of the processes involved in organic matter breakdown. We use a scanner to capture images of the different colour layers in sediments that result from a depth sequence of‘redox’ (reduction–oxidation) reactions. The interpretation of these colour profiles is aided by millimetre-scale profiling measurements of key pore-water solutes and the numerical model. “The model characterises the status quo of the sediment reactor and predicts its function under futurescenarios of human activities,” says NIWA aquatic ecologist Dr Kay Vopel. “The pore-water solute measurements help to fine-tune the performance of the model.” This three-pronged tool has many applications, including assessing the environmental effects of fish and mussel farming, urban development, and dredging on coastal regions. The tool has been developed with funding from NIWA and the Foundation for Research, Science & Technology.
Towards sustainable aquaculture
(National Institute of Water and Atmospheric Research (NIWA), 2008) Giles, H; Vopel, K; Pether, S
Development and validation of antibody screening cells specifically designed for Asian populations - the first example of the addition of peptide antigens to human red cells using KODE technology
(Blackwell Publishing Ltd, 2008-07-01) Heathcote, D; Henry, S; Flower, R
Background: Alloantibodies to antigens displayed on variant glycophorins are common in many Asian populations and have been shown to cause both transfusion reactions and haemolytic disease of the foetus and newborn new born. The detection of these antibodies is problematic as commercially available panels for antibody screening do not include the antigens necessary for detection of these antibodies. The use of naturally-occurring phenotype-positive cells is also problematic because not all antibodies detected are clinically significant, the specific epitope reactivity cannot be identified, and the RBC types required for full epitope analysis are of very limited availability. Aim: To use KODETM technology to add peptide epitopes to screening cells and to evaluate their stability and suitability for use in the detection of alloantibodies. The peptides investigated represented a series of defined variant MNS (Miltenberger) epitopes. These were used for the detection, identification and investigation of clinically significant alloantibodies, particularly alloantibodies found in Asian populations. Methods: Candidate carrier molecules were constructed and peptides attached. The epitope specificity of anti sera with generic anti-Mi(a) reactivity were characterized by ELISA. The candidate constructs were inserted into red cells and reactions in routine anti globulin test platforms were investigated. The stability of the transformed cells was also investigated. Results: There was no abnormal lysis of RBC expressing KODE -peptide antigens and the expression of these peptides on the transformed cells was stable with time. Detection of antibodies to other rbc antigens by IAT was the same for transformed and untransformed cells. Antibodies to variantMNS (Miltenberger) epitopes that have been reported to be clinically significant were detected for almost all serums for which a previous ELISA specificity had been defined. Summary: Various different KODE systems are suitable for addition of carbohydrate or protein antigens to human red blood cells. Under optimal conditions there is no change in the expression of other rbc blood group antigens. KODE technology allows for sensitive detection of clinically significant antibodies to vMNS antigens well as identification of their specific epitope reactivity.
Flow cytometric evaluation of red blood cells transformed with variable amounts of synthetic A and B glycolipids
(Blackwell Publishing Ltd, 2008-07-01) Hult, K; Frame, T; Henry, S; Olsson, ML
Background: According to national guidelines or directives, monoclonal ABO reagents may be required to detect Ax and B weak subgroup red blood cells (RBCs). Many routine laboratories do not have access to naturallyoccurring ABO subgroups that can be used as weak controls for these reagents. Group O RBCs modified with synthetic analogs of blood group A and/or B glycolipids (KODE technology) to mimic weak ABO subgroups could be used for quality control purposes. Aim: Extensive serological testing of KODE RBCs has previously been performed. An extended evaluation of KODE RBCs using flow cytometry was performed to explore the correlation between the concentrations of synthetic glycolipids and A/B site density of the resulting RBCs. The aim of this study was to examine if KODE RBCs mimic the distinct flow cytometric patterns of naturally-occurring ABO subgroups. Material and Methods: KODE RBCs were prepared according to a previously decribed procedure [Frame et al., Transfusion 2007; 47: 876–82]. RBCs were modified with 15 different concentrations of synthetic glycolipids, ranging from 1 mg/mL to 60 ng/mL for KODE-A and 5 mg/mL to 0.3 lg/mL for KODE-B. The concentration was decreased by doubling dilution steps. Sensitive and specific flow cytometry [Hult & Olsson. Transfusion 2006; 9S: 32A] was used to characterize and semiquantify the synthetic A and B antigen levels on RBCs. Relevant control RBCs (A1, A2, Ax, B, Bweak and O) were included in each run. For both KODE-A and KODE-B RBCs, repeat samples were produced for four selected concentrations and all KODE batches were tested in triplicate. Results: Flow cytometric testing of KODE RBCs modified with high concentrations of synthetic glycolipids revealed a uniform and even distribution of antigens in the cell population as shown by a single narrow peak in the FACS histograms. When lower concentrations were used, peaks tended to broaden to a pattern found in Ax and most B subgroups indicating a more variable antigen site density on the cells in the population. The concentrations of synthetic glycolipids that produced KODE cells that resembled the naturally-occurring subgroup control RBCs used in this study are ~2–4 lg/mL for KODE-A and ~10 lg/mL for KODEB. Repeat testing demonstrated good correlation between flow cytometric runs. Discussion and Conclusion: Using very low amounts of synthetic glycolipids, KODE-A and KODE-B RBCs can be made to mimic Ax and Bweak subgroup control RBCs, respectively, according to this flow cytometry method. With higher concentrations of synthetic glycolipids, the KODE RBCs demonstrated a more uniform and even distribution of antigens among the cells. This is in contrast to naturally-occurring subgroups in which some cells express almost no A or B antigen whilst others have close to normal levels. The reason for this is unknown. KODE RBCs obviously lack A carrying glycoproteins but it is not fully understood to what extent glycolipid versus glycoprotein epitopes contribute to the phenotype of weak subgroups. This study indicates that KODE RBCs with weak expression of A and/or B antigen have characteristics compatible with use as quality controls for monoclonal ABO reagents and could be a valuable addition in the serological laboratory.
The development of synthetic peptidolipids, glycolipids and other lipid-linked structures to create designer red cells
(John Wiley & Sons, 2008-09) Henry, S; Bovin, N
Background: Red cells used in immunohematology assays are restricted by their natural phenotype and membrane characteristics. More recently a technology has been developed which allows for the attachment of a large variety of specific carbohydrates, peptides and other structures to the surface of cells – known as FSL cell surface coating (KODETM technology). FSL constructs are water dispersible and consist of three components; a F functional head group, a S spacer and a L diacyl lipid tail. This technology allows users to introduce novel antigen profiles or characteristics at the membrane surface of cells. Methods: FSL constructs were synthesised bearing carbohydrates, peptides, and fluorophores. One part (0.05 ml) of FSL construct 1 mg/ml and one part of packed red cells were combined, mixed and incubated at 37°C for 2 hours, washed and then analysed for the presence of constructs by direct-indirect agglutination and fluorescence serological methods. Results: In all cases red cells were shown to be able to be precisely labelled with serologically detectable FSL construct. Red cells were modified to carry ABO, H, Lewis, acquired-B, the animal antigen Galili, hyaluronic acid, fluorophores and blood group peptides (Miltenberger). Conclusion: FSL cell surface coating technology allows for the creation of red cells expressing controlled levels of normal and/or novel antigens or structures. Such cells can be used for quality control, specialised antibody screening and identification panels and have potential for novel future applications.

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