Role of iron plaque in Cd uptake by and translocation within rice (Oryza sativa L.) seedlings grown in solution culture

A hydroponics culture experiment was conducted to investigate the effect of iron plaque on Cd uptake by and translocation within rice seedlings grown under controlled growth chamber conditions. Rice seedlings were pre-cultivated for 43 days and then transferred to nutrient solution containing six levels of Fe (0, 10, 30, 50, 80 and 100 mg L⁻¹) for 6 days to induce different amounts of iron plaque on the root surfaces. Seedlings were then exposed to solution containing three levels of Cd (0, 0.1 and 1.0 mg L⁻¹) for 4 days. In order to differentiate the uptake capability of Cd by roots with or without iron plaque, root tips (white root part without iron plaque) and middle root parts (with iron plaque) of pre-cultivated seedlings treated with 0, 30 and 50 mg L⁻¹ Fe were exposed to ¹⁰⁹Cd for 24 h. Reddish iron plaque gradually became visible on the surface of rice roots but the visual symptoms of the iron plaque on the roots differed among treatments. In general, the reddish color of the iron plaque became darker with increasing Fe supply, and the iron plaque was more homogeneously distributed all along the roots. The Fe concentrations increased significantly with increasing Fe supply regardless of Cd additions. The Cd concentrations in dithionite–citrate–bicarbonate (DCB)-extracts and in shoots and roots were significantly affected by Cd and Fe supply in the nutrient solution. The Cd concentrations increased significantly with increasing Cd supply in the solution and were undetectable when no Cd was added. The Cd concentrations in DCB-extracts with Fe supplied tended to be higher than that at Fe₀ at Cd_0.1, and at Cd_1.0, DCB-Cd with Fe supplied was significantly lower. Cd concentrations in roots and shoots decreased with increasing Fe supply at both Cd additions. The proportion of Cd in DCB-extracts was significantly lower than in roots or shoots. Compared to the control seedlings without Fe supply, the radioactivity of ¹⁰⁹Cd in shoots of seedlings treated with Fe decreased when root tips were exposed to ¹⁰⁹Cd and did not change significantly when middle parts of roots were exposed. Our results suggest that root tissue rather than iron plaque on the root surface is a barrier to Cd uptake and translocation within rice plants, and the uptake and translocation of Cd appear to be related to Fe nutritional levels in the plants.     

Genotypic variability within Tunisian grapevine varieties (Vitis vinifera L.) facing bicarbonate-induced iron deficiency

Morpho-physiological responses to bicarbonate-induced Fe deficiency were investigated in five Vitis vinifera L. Tunisian varieties (Khamri, Blanc3, Arich Dressé, Beldi, and Balta4). One-month-old woody cuttings were cultivated for 85 days on a free calcareous soil irrigated with tap water containing increasing bicarbonate levels (0, 4, 8, 12, and 16 mM NaHCO₃). After this screening, a second experiment compared root biochemical responses of two contrasting genotypes (tolerant-sensitive) dealing with bicarbonate-induced iron deprivation (20 μM Fe ± 10 mM HCO₃⁻) for 75 days. Using morpho-physiological criteria, grapevine tolerance to HCO₃⁻-induced Fe shortage appeared to be genotype-dependent: Balta4 and Beldi varieties showed the highest leaf-chlorosis score (especially at the extreme HCO₃⁻ levels), in contrast to Khamri variety. Growth parameters (shoot height, total leaf area, leaf number, and biomass production) as well as juvenile leaf chlorophyll content were also differently affected depending on both genotype and bicarbonate dose. At 16 mM HCO₃⁻, Khamri was the less sensitive variety, contrasting with Balta4. On the other hand, chlorophyll content correlated positively with HCl-extractible Fe content of the juvenile leaves, suggesting that the grapevine response to iron deficiency may partly depend on to the plant ability to adequately supply young leaves with this element. Root biochemical responses revealed a relatively higher root acidification capacity in Khamri (tolerant) under Fe-deficiency while no significant changes occurred in Balta4 (sensitive). In addition, Fe(III)-reductase and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activities were strongly stimulated by Fe-deficiency in Khamri, while remaining constant in Balta4. These findings suggest that biochemical parameters may constitute reliable criteria for the selection of tolerant grapevine genotypes to iron chlorosis.     

Effect of sulfate and iron on physico-chemical characteristics of anaerobic granular sludge

This research investigated the effect of the substrate composition (no substrate, glucose, glucose + sulfate or glucose + sulfate + iron) on the physico-chemical characteristics of two different anaerobic granular sludges as a function of time. The sludges were fed batch wise (pH 7, 30 °C) at an organic loading rate of 1.2 g COD l⁻¹ d⁻¹ (0.04 g COD g VSS⁻¹ day⁻¹) for 30 days. The presence of sulfate (COD/sulfate ratio = 1) in the feed of glucose fed anaerobic sludges did not change the physico-chemical characteristics throughout the incubation. In contrast, the presence of iron in the feed (in addition to glucose and sulfate, COD/iron ratio = 1) reduced the protein and carbohydrate content in the SMP and EPS with about 50% after 30 days incubation compared to the other feeding conditions. The sludge grown on glucose + sulfate + iron contained much more iron (+300–500%) and sulfur (+200–350%) than the other incubated sludges both after 14 and 30 days. The higher mineral content (lower VSS content) and the decrease of the EPS content contributed to the disintegration of iron fed granules, as shown by their lower size particles. However, the iron fed sludge displayed a higher granule strength than the other incubated sludges. Although an appreciable variation in the granule strength was noticed between the sludges investigated, it was not possible to relate these differences to their inorganic composition, the chemical composition of the extracted polymers or to the physical characteristics investigated.     

Coupled effects of irradiance and iron on the growth of a harmful algal bloom-causing microalga Scrippsiella trochoidea

Effects of irradiance and iron on the growth of a typical harmful algal blooms (HABs) causative dinoflagellate, Scrippsiella trochoidea, were investigated under various irradiances (high light: 70 μmol m^?2 s^?1 and low light: 4 μmol m^?2 s^?1) and iron concentrations (low iron: 0.063 mg L^?1, medium iron: 0.63 mg L^?1 and high iron: 6.3 mg L^?1), and evaluated by the parameters of algal cell density, specific growth rate, optical density and chlorophyll a content. The results indicated that there was significant difference in the cell density of dinoflagellate S. trochoidea between high light and low light intensity treatments across the entire experiments, 7-fold higher at high irradiance as compared with low irradiance, which was further enhanced by the iron concentration. It was found that the maximum cell density of 25 × 10⁴ cell mL^?1 occurred under the combination of high light intensity and high iron concentration, followed by 23 × 10⁴ cell mL^?1 in the combination of high light and medium iron, and 20 × 10⁴ cell mL^?1 in the combination of high light and low iron. There was no significant effect of iron concentration on the cell density under low light intensity. The cell density maintained about 3 × 10⁴ cell mL^?1 across all combinations of iron concentrations and low light in the end of experiments. Such interactive effects of light intensity and iron level dependent were also observed for the specific growth rate, OD₆₈₀ and chlorophyll a content of S. trochoidea. The maximum values of specific growth rate, OD₆₈₀ and chlorophyll a content peaked at the condition of high irradiance and high iron, which were 0.22 d^?1, 0.282 and 0.673 mg L^?1, respectively. In general, their values increased significantly with the increasing of iron concentration at high irradiance, whereas no significant difference was observed among three iron concentrations at low irradiance, all remaining approximately 0.06 d^?1, 0.03 and 0.050 mg L^?1, respectively. Those results suggest that there may be a strong interactive effect between irradiance and iron on microalgal growth and their physiological characteristics. The combination of high light and high iron concentration may accelerate algal cell growth and pigment biosynthesis, thus leading to massive occurrence of HABs.     

Effect of phytic acid,tannic acid and pectin on fasting iron bioavailability both in the presence and absence of calcium

ObjectiveTo determine the effect of phytic acid, tannic acid and pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.Research methodsTwenty-eight apparently healthy adult females participated in two iron absorption studies using radioactive iron isotopes (⁵⁹Fe and ⁵⁵Fe). One group received 5 mg of iron (as FeSO₄) alone (control), together with 10 mg of phytic acid, 100 mg of tannic acid and 250 mg of pectin (study A), on different days. The second group received the same iron doses and compounds as the other group, plus 800 mg of calcium (CaCl₂) (study B). The compounds were administered after an overnight fast, and no food or beverages were consumed for the following 3 h. Iron status and circulating radioactivity were measured in venous blood samples.ResultsThe geometric means of iron bioavailability (range ± 1SD) for iron alone, iron with phytic acid, iron with tannic acid, and iron with citrus pectin were 25.0% (11.9–52.0); 18.9% (9.9–35.8); 16.8% (8.7–32.3); and 21.1% (10.2–43.9), respectively (repeated-measures ANOVA, p < 0.02 (Dunnett's post hoc: control vs tannic acid p < 0.05). When 800 mg of calcium was added (study B), iron bioavailability was 16.7% (10.1–27.5); 13.2% (7.1–24.6); 14.8% (8.8–25.1); and 12.6% (5.5–28.8), respectively (repeated-measures ANOVA, NS).ConclusionsTannic acid decreases the fasting bioavailability of non-heme iron, however this effect did not exist in the presence of calcium. No effect was observed by phytic acid or citrus pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.     

Body mass index,iron absorption and iron status in childbearing age women

BackgroundThe prevalence of obesity has increased at an alarming rate worldwide. Some studies have observed an association between iron (Fe) deficiency (ID) and obesity, however more research is needed.ObjectiveTo assess whether body mass index (BMI) is associated with both Fe absorption and Fe status.MethodsA cross sectional sample of 318 Chilean childbearing age women was studied. The women received either a single dose of 0.5 mg of Fe (n = 137, group 1) or 3 mg of Fe plus ascorbic acid (1:2 molar ratio) (n = 181, group 2), both as FeSO₄ with labeled radioisotopes. Fe absorption was assessed through radio Fe erythrocyte incorporation. Fe status was determined by hemoglobin (Hb), mean corpuscular volume, serum Fe, total iron binding capacity, transferrin saturation, erythrocyte Zn protoporphyrin and serum ferritin (SF).Results29%, 47% and 24% of the women were classified as normal, overweight or obese, respectively. Fe absorption was significantly lower in obese women (p < 0.05). In group 1, the geometric mean and range ±1 SD of the percentage of Fe absorption for normal-weight women was 32.9% vs. 19.7% in obese. For group 2, this percentage was 36% vs. 30%, respectively (2-way ANOVA: BMI classification and Fe dose p < 0.05; interaction p = 0.34). Although Fe absorption was lower in obese women, they had higher SF (p < 0.01) and Hb (p < 0.05) concentrations.ConclusionAlthough we did not observe a relationship between BMI and Fe status, obese women displayed lower Fe absorption compared with overweight and normal weight women, possibly due to subclinical inflammation associated with obesity.     

Preparation of active corn peptides from zein through double enzymes immobilized with calcium alginate–chitosan beads

Double enzymes (alcalase and trypsin) were effectively immobilized in a composite carrier (calcium alginate–chitosan) to produce immobilized enzyme beads referred to as ATCC. The immobilization conditions for ATCC were optimized, and the immobilized enzyme beads were characterized. The optimal immobilization conditions were 2.5% of sodium alginate, 10:4 sodium alginate to the double enzymes, 3:7 chitosan solution to CaCl₂ and 2.5 h immobilization time. The ATCC beads had greatly enhanced stability and good usability compared with the free form. The ATCC residual activity was retained at 88.9% of DH (degree of hydrolysis) after 35 days of storage, and 36.0% of residual activity was retained after three cycles of use. The beads showed a higher zein DH (65.8%) compared with a single enzyme immobilized in the calcium alginate beads (45.5%) or free enzyme (49.3%). The ATCC kinetic parameters V_max and apparent K_m were 32.3 mL/min and 456.62 g⁻¹, respectively. Active corn peptides (CPs) with good antioxidant activity were obtained from zein in the ethanol phase. The ATCC might be valuable for preparing CPs and industrial applications.     

Decolorization of azo dye by immobilized Pseudomonas luteola entrapped in alginate–silicate sol–gel beads

Pseudomonas luteola was immobilized by entrapment in alginate–silicate sol–gel beads for decolorization of the azo dye, Reactive Red 22. The influences of biomass loading and operating conditions on specific decolorization rate and dye removal efficiency were studied in details. The immobilized cells were found to be less sensitive to changes in agitation rates (dissolved oxygen levels) and pH values. Michaelis–Menten kinetics could be used to describe the decolorization kinetics with the kinetic parameters being 36.5 mg g⁻¹ h⁻¹, 300.1 mg l⁻¹ and 18.2 mg g⁻¹ h⁻¹, 449.8 mg l⁻¹ for free and immobilized cells, respectively. After five repeated batch cycles, the decolorization rate of the free cells decreased by nearly 54%, while immobilized cells still retained 82% of their original activity. The immobilized cells exhibited better thermal stability during storage and reaction when compared with free cells. From SEM observation, a dense silicate gel layer was found to surround the macroporous alginate–silicate core, which resulted in much improved mechanical stability over that of alginate beads when tested under shaking conditions. Alginate–silicate matrices appeared to be the best matrix for immobilization of P. luteola in decolorization of Reactive Red 22 when compared with previous results using synthetic or natural polymer matrices.     

Mitochondrial calcium uniporter blocker effectively prevents brain mitochondrial dysfunction caused by iron overload

AimsAlthough iron overload induces oxidative stress and brain mitochondrial dysfunction, and is associated with neurodegenerative diseases, brain mitochondrial iron uptake has not been investigated. We determined the role of mitochondrial calcium uniporter (MCU) in brain mitochondria as a major route for iron entry. We hypothesized that iron overload causes brain mitochondrial dysfunction, and that the MCU blocker prevents iron entry into mitochondria, thus attenuating mitochondrial dysfunction.Main methodsIsolated brain mitochondria from male Wistar rats were used. Iron (Fe^2 + and Fe^3 +) at 0–286 μM were applied onto mitochondria at various incubation times (5–30 min), and the mitochondrial function was determined. Effects of MCU blocker (Ru-360) and iron chelator were studied.Key findingsBoth Fe^2 + and Fe^3 + entered brain mitochondria and caused mitochondrial swelling in a dose- and time-dependent manner, and caused mitochondrial depolarization and increased ROS production. However, Fe^2 + caused more severe mitochondrial dysfunction than Fe^3 +. Although all drugs attenuated mitochondrial dysfunction caused by iron overload, only an MCU blocker could completely prevent ROS production and mitochondrial depolarization.SignificanceOur findings indicated that iron overload caused brain mitochondrial dysfunction, and that an MCU blocker effectively prevented this impairment, suggesting that MCU could be the major portal for brain mitochondrial iron uptake.     

Magnetic susceptibility of iron in malaria-infected red blood cells

During intra-erythrocytic maturation, malaria parasites catabolize up to 80% of cellular haemoglobin. Haem is liberated inside the parasite and converted to haemozoin, preventing haem iron from participating in cell-damaging reactions. Several experimental techniques exploit the relatively large paramagnetic susceptibility of malaria-infected cells as a means of sorting cells or investigating haemoglobin degradation, but the source of the dramatic increase in cellular magnetic susceptibility during parasite growth has not been unequivocally determined. Plasmodium falciparum cultures were enriched using high-gradient magnetic fractionation columns and the magnetic susceptibility of cell contents was directly measured. The forms of haem iron in the erythrocytes were quantified spectroscopically. In the 3D7 laboratory strain, the parasites converted approximately 60% of host cell haemoglobin to haemozoin and this product was the primary source of the increase in cell magnetic susceptibility. Haemozoin iron was found to have a magnetic susceptibility of (11.0 ± 0.9) × 10^? 3 mL mol^? 1. The calculated volumetric magnetic susceptibility (SI units) of the magnetically enriched cells was (1.88 ± 0.60) × 10^? 6 relative to water while that of uninfected cells was not significantly different from water. Magnetic enrichment of parasitised cells can therefore be considered dependent primarily on the magnetic susceptibility of the parasitised cells.     

Single-step purification of recombinant green fluorescent protein on expanded beds of immobilized metal affinity chromatography media

Immobilized metal ion affinity chromatography (IMAC) in expanded bed mode is used for purifying recombinant green fluorescent protein (GFP) overexpressed in Escherichia coli. The purification is carried out on two different matrices, i.e. Ni²⁺ Streamline™ and Ni²⁺ cross-linked alginate beads. The binding isotherms to both IMAC media followed the Langmuir model. The maximum binding capacity (q_max) of Ni²⁺ Streamline™ and Ni²⁺ cross-linked alginate for the GFP was 1,42,860 FU ml⁻¹ and 18,000 FU ml⁻¹, respectively. The expanded bed column chromatography using Ni²⁺ Streamline™ gave 2.7-fold purification with 89% of GFP recovery, while Ni²⁺ alginate gave 3.1-fold purification with 91% of GFP recovery. SDS-PAGE of purified GFP in both cases showed single band. The results obtained in the expanded bed chromatography are compared with those obtained in packed bed chromatography.     

Relaxation dynamics in three polypyridyl iron(II)-based complexes probed by nanosecond and sub-picosecond transient absorption spectroscopy

The results of a sub-picosecond transient absorption spectroscopy study on a mononuclear and two dinuclear low-spin iron(II) complexes is reported. The dinuclear derivatives are homonuclear (i.e. Fe–Fe) and heterodinuclear (Fe–Zn) in nature. The ligands we used were 2-pyridylmethyl-ketazine and 2-pyridylmethyl-hydrazone. Irradiation was made on the metal-to-ligand CT band occurring around 500 nm. The observed pattern of the relaxation decays is consistent with the population of the metastable ⁵T₂ ligand field state within the first 100 fs after the photon absorption from the three different chromophores. The suggested implication of triplet intermediate states was not detected. The ground state recovery was observed to occur with a time constant of 350 ps for the mononuclear complex and 1600–1800 ps for the two dinuclear complexes.     

Alginate embedding and subsequent sporulation of in vitro-produced Conidiobolus thromboides hyphae using a pressurised air-extrusion method

Conidiobolus thromboides is an entomophthoralean fungus with potential as a biological control agent of aphids. However, its application in biological control is limited due to its formulation requirements. The objective of this study was to develop and optimise a novel air-extrusion method to embed C. thromboides hyphae at high density in alginate pellets. An orthogonal experimental design was used to investigate selected combinations of parameters known to affect hyphal density within pellets. The diameter of pellets produced, and the calculated density of hyphae within them, ranged from 0.18 ± 0.09 to 3.17 ± 0.06 mm and from 0.02 to 350.56 mg/mm³ respectively. These data were used to predict the optimal parameter combination to deliver the greatest density of hyphae of C. thromboides per pellet: 1% sodium alginate, a 1:2 ratio of hyphae to sodium alginate, an orifice diameter of 0.232 mm and an air pressure of 0.05 MPa. Pellets made under the optimal conditions predicted produced a mean total of 4.3 ± 0.6 × 10⁵ conidia per pellet at 100% relative humidity which was significantly greater than the mean total number of conidia produced from infected aphid cadavers of comparable size (9.35 ± 0.85 × 10⁴) (p < 0.001). In conclusion, air-extrusion embedding appears to be a promising method for formulating in vitro-produced hyphae of C. thromboides for use in biological control.     

Polynuclear water-soluble dinitrosyl iron complexes with cysteine or glutathione ligands: Electron paramagnetic resonance and optical studies

Electron paramagnetic resonance and optical spectrophotometric studies have demonstrated that low-molecular dinitrosyl iron complexes (DNICs) with cysteine or glutathione exist in aqueous solutions in the form of paramagnetic mononuclear (М-DNICs) and diamagnetic binuclear complexes (B-DNICs). The latter represent Roussin’s red salt esters and can be prepared by treatment of aqueous solutions of Fe²⁺ and thiols (рН 7.4) with gaseous nitric oxide (NO) at the thiol:Fe²⁺ ratio 1:1. М-DNICs are synthesized under identical conditions at the thiol:Fe²⁺ ratios above 20 and produce an EPR signal with an electronic configuration {Fe(NO)₂}⁷ at g_aver. = 2.03. At neutral pH, aqueous solutions contain both M-DNICs and B-DNICs (the content of the latter makes up to 50% of the total DNIC pool). The concentration of B-DNICs decreases with a rise in pH; at рН 9–10, the solutions contain predominantly M-DNICs. The addition of thiol excess to aqueous solutions of B-DNICs synthesized at the thiol:Fe²⁺ ratio 1:2 results in their conversion into М-DNICs, the total amount of iron incorporated into M-DNICs not exceeding 50% of the total iron pool in B-DNICs. Air bubbling of cys-М-DNIC solutions results in cysteine oxidation-controlled conversion of М-DNICs first into cys-B-DNICs and then into the EPR-silent compound Х able to generate a strong absorption band at 278 nm. In the presence of glutathione or cysteine excess, compound Х is converted into B-DNIC/M-DNIC and is completely decomposed under effect of the Fe²⁺ chelator о-phenanthroline or N-methyl-d-glucamine dithiocarbamate (MGD). Moreover, MGD initiates the synthesis of paramagnetic mononitrosyl iron complexes with MGD. It is hypothesized that compound Х represents a polynuclear DNIC with cysteine, most probably, an appropriate Roussin’s black salt thioesters and cannot be prepared by simple substitution of М-DNIC cysteine for glutathione. Treatment of М-DNIC with sodium dithionite attenuates the EPR signal at g_aver. = 2.03 and stimulates the appearance of an EPR signal at g_aver. = 2.0 with a hypothetical electronic configuration {Fe(NO)₂}⁹. These changes can be reversed by storage of DNIC solutions in atmospheric air. The EPR signal at g_aver. = 2.0 generated upon treatment of B-DNICs with dithionite also disappears after incubation of B-DNIC solutions in air. In all probability, the center responsible for this EPR signal represents М-DNIC formed in a small amount during dithionite-induced decomposition of B-DNIC.     

Lipase in biphasic alginate beads as a biocatalyst for esterification of butyric acid and butanol in aqueous media

Esterification of organic acids and alcohols in aqueous media is very inefficient due to thermodynamic constraints. However, fermentation processes used to produce organic acids and alcohols are often conducted in aqueous media. To produce esters in aqueous media, biphasic alginate beads with immobilized lipase are developed for in situ esterification of butanol and butyric acid. The biphasic beads contain a solid matrix of calcium alginate and hexadecane together with 5 mg/mL of lipase as the biocatalyst. Hexadecane in the biphasic beads serves as an organic phase to facilitate the esterification reaction. Under optimized conditions, the beads are able to catalyze the production of 0.16 mmol of butyl butyrate from 0.5 mmol of butyric acid and 1.5 mmol of butanol. In contrast, when monophasic beads (without hexadecane) are used, only trace amount of butyl butyrate is produced. One main application of biphasic beads is in simultaneous fermentation and esterification (SFE) because the organic phase inside the beads is very stable and does not leach out into the culture medium. SFE is successfully conducted with an esterification yield of 6.32% using biphasic beads containing iso-octane even though the solvent is proven toxic to the butanol-producing Clostridium spp.     

Removal of iron,arsenic and coliform bacteria from water by novel constructed soil filter system

The present paper presents results of the study in removal of iron, arsenic and total coliform from drinking water using single-pass constructed soil filter (CSF). Results indicated that arsenic levels ranged from 0.5 to less than 10 μg l^?1 levels; iron from 5 to less than 0.3 mg l^?1 and coliform from 10^?5 to less than 5 CFU/100 ml. The results revealed very high removal efficiency, i.e., over 99% and water quality as per WHO standard.     

Dried alginate-entrapped enzymes (DALGEEs) and their application to the production of fructooligosaccharides

A modification of the classical calcium alginate enzyme entrapment technique is described aiming to overcome some of the limitations of the former gel-based biocatalysts. Dried alginate entrapped enzymes (DALGEEs) were obtained dehydrating calcium alginate gel beads containing entrapped enzymes. A fructosyltransferase from Aspergillus aculeatus, present in Pectinex Ultra SP-L, was entrapped using this technique. The resulting DALGEEs were successfully tested both operating batchwise and in a continuous fixed-bed reactor for fructooligosaccharides (FOS) synthesis from sucrose. Interestingly, DALGEEs did not re-swell upon incubation in concentrated (600 g/L) sucrose solutions, probably due to the lowered water activity (a_w) of such media. Confocal laser scanning microscopy of DALGEEs revealed that the enzyme molecules accumulated preferably in the shell of the particles. DALGEEs showed an approximately 30-fold higher volumetric activity (300 U/mL) compared with the calcium alginate gel beads. Moreover, a significant enhancement (40-fold) of the space-time-yield of fixed-bed bioreactors was observed when using DALGEEs as biocatalyst compared with gel beads (4030 g/day L of FOS vs. 103 g/day L). The operational stability of fixed-bed reactors packed with DALGEEs was extraordinary, providing a nearly constant FOS composition of the outlet during at least 700 h. It was also noticeable their resistance against microbial attack, even after long periods of storage at room temperature. The DALGEEs immobilisation strategy may also be useful for other biotransformations, in particular when they take place in low a_w media.     

l-Lysine supplementation does not affect the bioavailability of copper or iron in rats

l-lysine (Lys) is an essential amino acid that is added to foods and dietary supplements. Lys may interact with mineral nutrients and affect their metabolism. This study examined the effect of dietary Lys supplementation on the bioavailability of copper (Cu) and iron (Fe). Weanling male Sprague-Dawley rats were fed one of five diets (20% casein) for 4 weeks containing normal Cu and Fe (control) or low Cu or Fe without (LCu, LFe) or with (LCu + Lys, LFe + Lys) addition of 1.5% Lys. Final body weights, body weight gains and food consumption of the rats did not differ (P ≥ 0.05) among diet groups. Rats fed the low Cu or Fe diets showed changes in nutritional biomarkers compared to control rats, demonstrating reduced Cu and Fe status, respectively. Hematological parameters, serum ceruloplasmin activity and Cu and Fe concentrations in serum, liver, kidney and intestinal mucosa were unaffected (P ≥ 0.05) by Lys supplementation. These results indicate that in the context of an adequate protein diet, Lys supplementation at a relatively high level does not affect Cu or Fe bioavailability in rats.     

Increased whole blood manganese concentrations observed in children with iron deficiency anaemia

A prospective observational study was carried out at Alder Hey Children's Hospital, Liverpool, England, UK on children aged 1–6 years attending the pathology department for routine blood tests (n = 225). Whole blood manganese concentrations were measured plus the following markers of iron status; haemoglobin, MCV, MCH, RBC count, ferritin, transferrin saturation and soluble transferrin receptors. Multiple regression analysis was performed, with blood manganese as the dependent variable and factors of iron status, age and gender as independent variables. A strong relationship between blood manganese and iron deficiency was demonstrated (adjusted R² = 34.3%, p < 0.001) and the primary contributing factors to this relationship were haematological indices and soluble transferrin receptors. Subjects were categorised according to iron status using serum ferritin, transferrin saturation and haemoglobin indices. Children with iron deficiency anaemia had higher median blood manganese concentrations (16.4 μg/L, range 11.7–42.4, n = 20) than children with iron sufficiency (11 μg/L, range 5.9–20.9, n = 59, p < 0.001). This suggests that children with iron deficiency anaemia may be at risk from manganese toxicity (whole blood manganese >20 μg/L), and that this may lead to neurological problems. Treatment of iron deficiency in children is important both to improve iron status and to reduce the risk of manganese toxicity.     

Iron bioavailability of common beans (Phaseolus vulgaris L.) intrinsically labeled with 59Fe

A radiobioassay was performed in rats with or without iron depletion to evaluate the iron bioavailability of diets enriched with common beans and with “multimixture”, a nutritional supplement based on parts of foods that are not usually eaten. The full-body ⁵⁹Fe level was determined after 5 h, the absorbed ⁵⁹Fe level was determined after 48 h, and the amount of ⁵⁹Fe retained was determined after 7 days. Iron bioavailability was assessed by the full-body radioactivity of the animals, determined using a solid scintillation detector. The iron bioavailability of common beans was higher in the iron-depleted animals (55.7%) than in the non-depleted animals (25.12%) because of the higher absorption rate in the iron-depleted animals. The multimixture did not influence dietary iron bioavailability. In addition, the iron bioavailability of common beans was similar to that observed in the standard source of iron for Wistar rats. Hence, common beans may be considered an adequate dietary iron source because of its high bioavailability.