Each of two affinity isolation methods, the first based on biotinylated porcine transferrin plus streptavidin-agarose, and the second on Sepharose-coupled porcine transferrin, followed by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE), allowed the isolation and identification of two potential porcine-transferrin-binding polypeptides (∼64 kDa and 99 kDa) from total membranes of Actinobacillus pleuropneumoniae grown under iron-restricted conditions. Both polypeptides were iron-repressible and were identified as potential receptor candidates as they were not isolated when biotinylated human transferrin was used instead of biotinylated porcine transferrin. The 64 kDa polypeptide was the more easily removed from Sepharose-coupled porcine transferrin and only the 99 kDa polypeptide appeared to be an outer membrane protein. These results suggest that the 99 kDa polypeptide represents the porcine transferrin receptor of A. pleuropneumoniae, and that the 64 kDa polypeptide represents an associated protein serving an accessory role. Fe+3 uptake studies using plate assays and attempted isolation of a putative lactoferrin receptor using biotinylated porcine lactoferrin plus streptavidin-agarose, followed by SDS-PAGE, showed that A. pleuropneumoniae lacks a mechanism for the use of porcine lactoferrin as an iron source.

Three species of photosynthetic flagellates capable of phagotrophy (mixotrophic species) were tested for their abilities to use inorganic iron colloids for growth. Ochromonas sp., Chrysochromulina ericina (a coastal strain) and C. ericina (an oceanic strain) were grown in iron-free seawater supplemented with 1 muM goethite, hematite, magnetite/maghemite or ferrihydrite (90°) in the presence and absence of desferrioxamme B, an iron-binding siderophore. Both strains of Chrysochromulina grew at 35--70% of their maximum rates with goethite, hematite, and magnetite/maghemite, but were unable to use ferrihydrite. Ochromonas, however, grew well with ferrihydrite, but could not use any of the other forms. All the flagellates were able to acquire iron from ingested bacteria. Diatoms that were known only to take up dissolved forms of iron, Thalassiosira oceanica (clone 1003) and T. pseudonana (clone 3H), were unable to use any of the colloids tested. The mechanism of iron acquisition by the flagellates appeared to involve ingestion of the iron colloids as DFB had no effect on colloidal iron availability and bacteria resident in the cultures were unable to use the iron contained in the colloids. Variations in the size of the colloids were hypothesized to account for differences in their availability, independent of colloid chemical stability. The results provide the first strong evidence for direct utilization (i.e. without prior dissolution) of colloidal iron by mixotrophic phytoplankton and document a new pathway of iron acquisition that may be important for their survival in low-iron waters of the sea.

Iron is essential in nearly all organisms. It is a cofactor in many proteins and enzymes. This transition metal can also be toxic because it participates in reactions which produce reactive oxygen species. To avoid these toxic effects while still being used for essential processes, the cell must regulate tightly iron import, metabolism, trafficking, and homeostasis. These processes were studied using biophysical methods centered on Mossbauer spectroscopy supplemented by electron paramagnetic resonance, electronic absorption spectroscopy, and inductively coupled plasma mass spectrometry. This integrated biophysical approach was applied to yeast cells, isolated yeast mitochondria, and mouse brains. We determined the concentration of Fe, and the proportion of that Fe present as iron-sulfur clusters, heme centers, mononuclear nonheme centers, and as Fe3+ oxyhydroxide (phosphate) nanoparticles for each system. In yeast, the dependence of metabolic mode of growth and iron in the growth medium on this distribution was studied. Approximately three-quarters of the iron in fermenting cells was located in vacuoles, where it was present as high-spin mononuclear Fe3+ species with rhombic symmetry. The remaining quarter was present in the mitochondria. In fermenting mitochondria 4 distinct species of iron were observed, including [Fe4S4]2+ clusters and low-spin Fe2+ hemes arising from respiratory complexes, non-heme high spin (NHHS) Fe2+ species, high spin nonheme Fe3+ species, and nanoparticles. These distributions (in both the cells and mitochondria) change when the cells are grown on iron deficient medium but remained relatively unaltered as iron in the growth medium was increased. Respiring cells had less Fe associated with vacuoles, and more Fe present as HS Fe2+. Respiring mitochondria contain more [Fe4S4]2+ clusters and low-spin Fe2+ hemes, more S = 1/2 [Fe2S2]1+ clusters, and less NHHS Fe2+, HS Fe3+ species and Fe3+ nanoparticles. These changes were rationalized by assuming that the NHHS Fe2+ and Fe3+ species, and the nanoparticles were in equilibrium within the matrix of the mitochondria, and that the Fe2+ species served as feedstock for the synthesis of iron-sulfur clusters and heme centers. The iron in the mouse brain consisted mostly of [Fe4S4]2+ clusters and Fe2+ hemes from mitochondria respiratory complexes, and of ferritin, an Fe storage protein complex. NHHS Fe2+ and Fe3+ species were also observed. The ratio of stored Fe to mitochondrial Fe was sensitive to age. The brains of prenatal animals were dominated by ferritin. Following birth up to the first 4 weeks of life, there was an increase in mitochondrial Fe and a decline of ferritin Fe. Beyond 4 weeks up to 58 weeks, levels of ferritin increased and mitochondrial Fe remained constant. The brains of mice fed an Fe-deficient diet were also studied; most of the Fe in these brains was present as mitochondrial Fe, with little stored as ferritin. A model was developed to explain these changes.

Thesis--University of Göteborg, 1970.

Thesis--University of Göteborg, 1970.

Corrigenda tipped to title page. Bibliography: leaves 313-353. This study investigated the iron status and dietary intakes in 6-24 month old children in Australia and Ghana and assessed the effects of dietary calcium on intestinal iron absorption. The true prevalence of non-anaemic iron deficiency (NAID) and iron deficiency anaemia (IDA) and dietary intakes in infants and toddlers from a broad socio-economic background were assessed by haematological and biochemical parameters, semi-quantitative diet recall and anthropometric measurements. The high prevalence of iron deficiency and anaemia found in Australian and Ghanaian children can be attributed to the low intake of bioavailable iron in weaning diets which are often ingested with large amounts of calcium. While calcium has been shown to inhibit the absorption of iron, its mechanism of interaction with iron absorption at the intestinal level is not known. The rat was used as an experimental model to investigate the effects of dietary calcium on duodenal iron uptake. The results indicate there is a critical period during weaning when the consumption of high dietary calcium with low iron can retard growth potential. Dietary calcium significantly inhibits non-haem iron absorption at the intracellular level by up-regulating villus enterocyte ferritin concentrations under iron deficiency conditions.

Thesis (MSc (Genetics))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Oesophageal cancer (OC) is characterised by the development of malignant tumours in the epithelial cells lining the oesophagus. It demonstrates marked ethnic variation, with squamous cell carcinoma (SCC) being more prevalent in the Black population and adenocarcinoma (ADC) occurring more often in Caucasians. The aetiology of this complex disease has been attributed to a variety of factors, including an excess of iron (resulting in increased tumourigenesis), oesophageal injury and inflammation. The present study attempted to determine the mutation spectrum of the regulatory and coding regions of the ceruloplasmin (CP) gene, involved in iron metabolism, in the Black South African OC population. The patient cohort was comprised of 96 (48 male and 48 female) unrelated individuals presenting with SCC of the oesophagus. The control group consisted of 88 unrelated, healthy population-matched control individuals. The techniques employed for mutation detection in this study included polymerase chain reaction (PCR) amplification, heteroduplex single-strand conformation polymorphism (HEX-SSCP) analysis, restriction fragment length polymorphism (RFLP) analysis followed by bidirectional semi-automated DNA sequencing analysis to verify the variants identified. Mutation detection of CP resulted in the identification of fourteen previously described (5’UTR-567C→G, 5’UTR-563T→C, 5’UTR-439C→T, 5’UTR-364delT, 5’UTR-354T→C, 5’UTR-350C→T, 5’UTR-282A→G, V223, Y425, R367C, D544E, IVS4-14C→T, IVS7+9T→C and IVS15-12T→C) and four novel (5’UTR-308G→A, T83, V246A and G633) variants. Statistical analysis revealed that two of the novel variants were significantly associated with OC in this study; the promoter variant 5’UTR-308G→A (P=0.012) and the exonic variant G633 (P=0.0003). It is possible that these variants may contribute to OC susceptibility in the Black South African population. OC symptoms generally present late in the development of the disease, and as a result treatment after diagnosis is highly ineffective. Early detection of symptoms and subsequent treatment is therefore the most effective manner of disease intervention. In high incidence areas, such as the Transkei region of South Africa, the implementation of a screening programme would be the ideal way to achieve this goal. The information that can be gathered from the identification of potential modifier genes for OC can lead to improvements in early detection, which in turn may lead to advancements in the treatment and counselling to individuals with OC. To our knowledge, this is the first study concerning CP and its effects on iron dysregulation in the Black South African population with oesophageal cancer. / AFRIKAANSE OPSOMMING: Oesofageale kanker word gekenmerk deur die ontwikkeling van kwaardaardige gewasse in die epiteelweefsel van die oesofageale voering. Hierdie siekte demonstreer opvallende etniese variasie, met plaveisel selkarsinoom meer algemeen in die Swart populasie en adenokarsinoom meer algemeen in die Kaukasiese populasie. Die ontwikkeling van hierdie komplekse siekte word aan ‘n aantal faktore toegeskryf, insluitend ‘n oormaat yster (wat lei tot ‘n vermeerdering van gewasse) en oesofageale besering en -ontsteking. Die doel van die hierdie studie was om die mutasie spektrum van die regulatoriese- en koderingsarea van die ceruloplasmin (CP) geen, betrokke in yster metabolisme, in die Swart Suid Afrikaanse oesofageale kanker populasie te bepaal. Die pasiënt groep het bestaan uit 96 (48 manlik en 48 vroulik) onverwante individue met plaveisel selkarsinoom van die oesofagus. Die kontrole groep het uit 88 nie-geaffekteerde onverwante, populasie spesifieke individue bestaan. Die tegnieke aangewend vir mutasie deteksie in hierdie studie sluit in polimerase kettingsreaksie amplifikasie, heterodupleks enkelstring konformasie polimorfisme analise en restriksie fragment lengte polimorfisme analise, gevolg deur tweerigting semi-geoutomatiseerde DNS volgorde-bepalingsanalise om die geïdentifiseerde variante te bevestig. Mutasie deteksie van CP het tot die identifikasie van veertien reeds beskryfde (5’UTR-567C→G, 5’UTR-563T→C, 5’UTR-439C→T, 5’UTR-364delT, 5’UTR-354T→C, 5’UTR-350C→T, 5’UTR-282A→G, V223, Y425, R367C, D544E, IVS4-14C→T, IVS7+9T→C en IVS15-12T→C) en vier nuwe (5’UTR-308G→A, T83, V246A en G633) variante gelei. Statistiese analise het getoon dat twee van die nuwe variante betekenisvol geassosieerd was met oesofageale kanker in hierdie studie; die promotor variant 5’UTR-308G→A (P=0.012) en die eksoniese variant G633 (P=0.0003). Dit is moontlik dat hierdie variante mag bydra tot oesofageale kanker vatbaarheid in die Swart Suid Afrikaanse populasie. Oesofageale kanker simptome vertoon gewoonlik op ‘n latere stadium in die ontwikkelingsproses van die siekte, en as ‘n gevolg is behandeling na diagnose hoogs oneffektief. Vroegtydige identifikasie van die simptome en daaropvolgende behandeling is die mees effektiewe manier vir ingryping. In hoë voorkoms streke, soos die Transkei gebied van Suid Afrika, sal die implementasie van ‘n siftingsprogram die ideale manier wees om hierdie doel te bereik. Die inligting wat dan versamel word, insluitend identifisering van modifiserende gene vir oesofageale kanker, kan lei tot ‘n verbetering in vroegtydige deteksie van die siekte. In effek kan dit dan lei tot beter behandeling en berading vir individue met oesofageale kanker. So ver ons kennis strek, is hierdie die eerste studie wat CP en sy effek op yster disregulasie in die Swart Suid-Afrikaanse populasie met oesofageale kanker behels.

Thesis (MSc)--Stellenbosch University, 2010. / ENGLISH ABSTRACT: Oesophageal cancer (OC) is a disease characterised by development of malignant tumours in the cell lining of the oesophagus. The disease is divided into two subtypes, which shows marked ethinic variation, with adenocarcinoma (ADC) being more prevalent in Caucasians and squamous cell carcinoma (SCC) more prevalent in the Black population. There are several factors that have been associated with OC development, including oesophageal injury and inflammation, as well as excess iron, which contributes to increased tumour growth. Investigation into OC development is essential due to the rapidly increasing incidence rates and the poor survival rate of this complex disease. The present study aimed to investigate nucleotide variation in the promoter region of SLC40A1, a gene implicated in iron metabolism, in a Black South African OC population. The patient group encompassed 80 (41 males and 39 females) unrelated patients presenting with SCC of the oesophagus. The control group consisted of 71 unrelated, healthy population-matched control individuals. The techniques applied for mutation detection in this study included polymerase chain reaction (PCR) amplification, heteroduplex single stranded conformation polymorphism (HEXSSCP) analysis, restriction fragment length polymorphism (RFLP) analysis and hybridisation probe analysis. Identified variants were confirmed by bi-directional semi-automated DNA sequencing analysis. Statistical analysis was performed to determine associations between identified variants and disease incidence, as well as between identified variants and various iron parameters. Mutation analysis of the promoter region of SLC40A1 resulted in the identification of nine previously described (-1470C/T, -1461T/C, -1399G/A, -1355G/C, -1098G/A, -750G/A, -501T/C, - 23A/G and -8C/G) and three novel, (-1087G/C, -663C/T and -637G/A) variants as well as a previously described trinucleotide repeat. Statistical analyses revealed statistically significant association between -501T/C and OC in this population (P = 0.004). Statistical investigation of the effect of the variants on iron parameters revealed various statistically significant associations. The survival rate of OC remains poor due to absence of early symptoms and therefore late diagnosis of the disease, after which treatment is highly ineffective. Treatment of OC would significantly improve with earlier detection and treatment. This can be achieved by establishing a screening programme in the populations of high risk areas, such as the Transkei area in Southern Africa. Therefore investigation into nucleotide variation of potential modifier genes is of great importance to improved diagnosis, treatment and counselling to individuals presenting with OC. To our knowledge, this is the first study investigating the promoter region of SLC40A1 and possible associations with iron dysregulation in the Black South African population with OC. / AFRIKAANSE OPSOMMING: Oesofageale kanker is ‘n siekte wat gekenmerk word deur die ontwikkeling van kwaadaardige gewasse in the selvoering van die oesofagus. Die siekte word verdeel in twee subtipes wat opvallende etniese variasie toon, met adenokarsinoom wat meer algemeen in die Kaukasiese populasie voorkom en plaveisel selkarsinoom wat meer algemeen in die Swart populasie is. Daar is verskeie faktore wat verbind word met die ontwikkeling van oesofageale kanker, insluitend oesofageale besering en ontsteking, asook ‘n oormaat yster wat bydra tot verhoogde gewasgroei. Ondersoek met betrekking tot die ontwikkeling van oesofageale kanker is noodsaaklik as gevolg van die verhoogde voorkoms-tempo en die swak oorlewingsyfers van hierdie komplekse siekte. Die huidige studie het beoog om die nukleotied variasie in die promoter area van SLC40A1, ‘n geen betrokke in yster metabolisme, in ‘n Swart Suid-Afrikaanse oesofageale kanker populasie te ondersoek. Die pasiënt-groep het bestaan uit 80 (41 mans en 39 vrouens) onverwante pasiënte by wie plaveisel selkarsinoom van die oesofagus voorgekom het. Die kontrole groep het bestaan uit 71 onverwante, gesonde bevolkings-soortgelyke individue. Die tegnieke wat gebruik is vir mutasie opsporing in hierdie studie sluit in: polimerase kettingreaksie amplifikasie, heterodupleks enkelstring konformasie polimorfisme (HEX-SSCP) analise, restriksie fragment lengte polimorfisme (RFLP) analise en hibridisasie peiler analise. Geïdentifiseerde variante is bevestig deur tweerigting semi-geoutomatiseerde DNS volgorde-bepalingsanalise. Statistiese analise is uitgevoer om moontlike assosiasies tussen geïdentifiseerde variante en siekte voorkoms, sowel as tussen geïdentifiseerde variante en verskeie yster parameters te bepaal. Mutasie analise van die promoter area van SLC40A1 het gelei tot die identifikasie van nege voorheen bekende (-1470C/T, -1461T/C, -1399G/A, -1355G/C, -1098G/A, -750G/A, -501T/C, - 23A/G and -8C/G) en drie nuwe (-1087G/C, -663C/T and -637G/A) variante, sowel as ‘n bekende trinukleotied herhaling. Statistiese analise het getoon dat daar ‘n statistiese betekenisvolle assosiasie tussen -501T/C en oesofageale kanker in hierdie populasie voorkom (P = 0.004). Statistiese ondersoek van die effek van die geïdentifiseerde variante op yster parameters het verskeie statisties betekenisvolle assosiasies getoon. Die oorlewingsyfers van oesofageale kanker bly laag as gevolg van die afwesigheid van vroeë simptome en dus word die siekte eers op ‘n laat stadium gediagnoseer, waarna behandeling hoogs oneffektief is. Behandeling van oesofageale kanker sou betekenisvol verbeter met vroegtydige identifikasie en behandeling. Dit is bereikbaar deur die vestiging van ‘n siftingsprogram vir die populasies van hoë risiko areas, soos die Transkei area in Suidelike Afrika. Ondersoeke na die nukleotied variasie van potensiële modifiserende gene kan daarom van groot belang wees vir verbeterde diagnose, behandeling en berading van individue met oesofageale kanker. Sover as wat ons kennis strek, is hierdie die eerste studie wat die promoter area van die SLC40A1 geen en die moontlike effek op yster disregulasie in ‘n Swart Suid-Afrikaanse populasie met oesofageale kanker ondersoek.

Philosophiae Doctor - PhD / Blood feeding is a habit exhibited by many insects. Considering the devastating impact of these insects on human health, it is important to focus research on understanding the biology behind blood-feeding, disease transmission and host-pathogen interactions. Such knowledge would pave the way for developing efficient preventative measures. Iron an important element for species survival, is at the center of events controlling tsetse’s fitness and reproductive success. Hence, targeting genes involved in iron trafficking and sequestration would present possible means of preventing disease transmission. Considering the dynamic and multi-factorial nature of iron metabolism, a well-coordinated regulatory system is expected to be at work. Despite extensive literature on the mechanism of iron regulation and key factors responsible in maintaining its homeostasis in human, less attention has been given to understand such system in insects, especially the blood-feeding insects. The availability of the genome sequences for several insect disease vectors allows for a more detailed analysis on the identification and characterization of events controlling and preventing iron-induced toxicity following a blood-meal. The International Glossina Genome Initiative (IGGI) has coordinated the sequencing and annotation of the Glossina morsitans genome that has led to the identification of 12220 genes. This knowledge-base along with current understanding of the IRE system in regulating iron metabolism, allowed for investigating the UTRs of Glossina genes for the presence of these elements. Using a combination of motif enrichment and IRE-stem loop structure prediction, an IRE-mediated regulation was inferred for 150 genes, among which, 72 were identified with 5’-IREs and 78 with 3’-IREs. Of the identified IRE-regulated genes, the ferritin heavy chain and MRCK-alpha are the only known genes to have IREs, while the rest are novel genes for which putative roles in regulating iron levels in tsetse fly have been assigned in this study. Moreover, the functional inference of the identified genes further points to the enrichment of transcription and translation. Furthermore, several hypothetical proteins with no defined functions were identified to be IRE-regulated. These include TMP007137, TMP009128, TMP002546, TMP002921, TMP003628, TMP004581, TMP008259, TMP012389, TMP005219, TMP005827, TMP007908, TMP009332, TMP01- 3384, TMP009102, TMP010544, TMP010707, TMP004292, TMP006517, TMP014030, TMP009821 and TMP003060 for which an iron-regulatory mechanism of action may be inferred. We further report 26 IRE-regulated secreted proteins in Glossina, that present good candidates for further investigation pertaining to the development of novel vector control strategies. Using the predicted data on the identified IRE-regulated genes and their functional classification, we derived at 29 genes with putative roles in iron trafficking, where several unknown and hypothetical proteins are included. Thus a novel role is inferred for these genes in cellular binding and transport in the context of iron metabolism. It is therefore possible that these genes may have evolved in Glossina, such that they compensate for the absence of an IRE- regulated mechanism for transferrin. Additionally, we propose 14 IRE-regulated genes involved in immune and stress response, which may indeed play crucial roles at the host pathogen interface through their possible mechanisms of iron sequestration. Using the subcellular localization analysis, we further categorized the putative IRE regulated genes into several subcellular localizations, where the majority of genes were found within the nucleus and the cytosol. The detection of the conserved motifs in a set of genes, is an interesting yet sophisticated area of research, that allows for identifying either co-regulated or orthologous genes, while further providing support for the putative function of a set of genes that would otherwise remain uncharacterized. This is based on the notion that co-regulated genes are often coexpressed to carry out a specific function. As such, 14 regulatory elements were identified in the 5’- and 3’-UTRs of IRE-regulated genes, involved in embryonic development and reproduction, inflammation and immune response, signaling pathways and neurogenesis as well as DNA repair. This study further proposes several IRE-regulated genes as targets for micro-RNA regulation through identifying micro-RNA binding sites in their 3’UTRs. Using a motif clustering approach we clustered IRE-regulated genes based on the number of motifs they share. Significantly co-regulated genes sharing two or more motifs were determined as critical targets for future investigation. The expression map of IRE-regulated genes was analyzed to better understand the events taking place from 3 hours to 15 days following a blood meal. Re-analysis of Anopheles microarray chip showed the significant expression of three cell envelope and transport genes as early response and six as late response to a blood meal, which could indeed be assigned a putative role in iron trafficking. Genes identified in this study with implications in iron metabolism, whose timely expression allows for maintaining iron homeostasis, represent good targets for future work. Considering the important role of evolution in species adaptation to habits such as Hematophagy, it is of importance to identify evolutionary signatures associated with these changes. To distinguish between evolutionary forces that are specific to iron-metabolism in blood-feeding insects and those that are found in other insects, the IRE-regulated genes were clustered into orthologous groups using several blood feeding and non-blood feeding insect species. Assessment of different evolutionary scenarios using the Maximum Likelihood (ML) approach, points to variations in the evolution of IRE-regulated genes between the two insect groups, whereby several genes indicate an increased mutation rate in the BF-insect group relative to their non-blood feeding insect counterparts. These include TMP003602 (phosphoinositide3-kinase), TMP009157 (ubiquitin-conjugating enzyme9), TMP010317 (general transcription factor IIH subunit1), TMP011104 (serine-pyruvate mitochondrial), TMP013137 (pentatricopeptide Transcription and translation), TMP013886 (tRNA(uridine-2-o-)-methyl-transferase-trm7) and TMP014187 (mediator 100kD). Additionally, we have indicated the presence of positively selected sites within seven blood-feeding IRE-regulated genes namely TMP002520 (nucleoporin), TMP008942 (eukaryotic translation initiation factor 3), TMP009871(bruno-3 transcript) , TMP010317 (general transcription factor IIH subunit1), TMP010673 (ferritin heavy-chain protein), TMP011104 (serine-pyruvate mitochondrial) and TMP011448 (brain chitinase and chia). Thus the results of this study provides an in depth understanding of iron metabolism in Glossina morsitans and confers important targets for future validations based on which innovative control strategies may be designed.

Male weanling Wistar rats were fed a low-iron basal diet for 3 weeks. The iron depleted rats were then divided into 9 groups according to a randomized block design based on body weight. During the repletion period of 2 weeks, one group was fed the low-iron basal diet. The other eight groups received either the basal diet to which was added 5, 10, 15, 20 or 25 mg iron per kg diet as ferrous sulfate or test source diets formulated to provide a total of 15 mg iron per kg diet from either freeze-dried ground beef, textured defatted soy flour product or a 2.3:1 (w/w) mixture of beef and soy product. All diets were isocaloric and isonitrogenous. The relative biological value (RBV) of iron in the test source diet was calculated as the ratio of the amounts of iron from the reference source (ferrous sulfate) and the test source diet required to give the same response in hemoglobin or hematocrit. The RBVs ± 95% confidence limits, calculated on the basis of final hemoglobin levels and hematocrit values, were respectively: freeze-dried ground beef, 56 ± 7 % and 62 ± 7 %; fortified textured defatted soy flour product, 81 ± 10 % and 79 ± 10 %; 2.3:1 (w/w) mixture of freeze-dried ground beef and soy flour product, 65 ± 6 % and 68 ± 6 %. The RBVs obtained for the iron in beef and for that in the soy flour product suggest that the anemic rat might not be a suitable model for normal man when screening such foods for their available iron. In normal man, the absorption of the iron in beef is comparable to that of inorganic reference iron, while that in textured soy flour is about one third. / Land and Food Systems, Faculty of / Graduate