The effect of amino acid deprivation on the transfer of iron through Caco-2 cell monolayers

Funding Source Rural and Environmental Scientific and Analytical Services, the Scottish Government Acknowledgments We thank Dr Helen Hayes for her technical support during this project. We also thank Dr Christine Kennedy for her involvement at the beginning of this project. This study was funded by Rural and Environmental Scientific and Advisory Service of Scottish Government.Peer reviewedPostprin

Transcriptional regulation of copper metabolism genes in the liver of fetal and neonatal control and iron-deficient rats

Acknowledgments The authors’ work is supported by Scottish Government (Rural and Environmental Scientific and Analytical Services). We are grateful to Ms Val Stevens for analytical and technical assistance and to the Biological Resource Facility staff for husbandry and maintenance of the experimental animals. The authors declare no conflicts of interest. Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Peer reviewedPublisher PD

Comparative studies on the sarcoplasmic reticulum of fish muscle

1. The sarcoplasmic reticulum from fish red and white muscle has been isolated and compared with that of mammalian sarcoplasmic reticulum (SR). The white muscle SR is shown to be similar to mammalian fast muscle with the majority of the protein being accounted for by a band with molecular weighty of approximately 100,000. This has been demonstrated in several species to correspond to the calcium pump protein. The red muscle SR pumps Ca2+ ions and hydrolyses ATP at approximately half the rate of the white SR. Gel electrophoresis of the SR vesicles shows that there is not sufficient 100,000 dalton protein in the red muscle SR to account for the relative rates of pumping. It is suggested that fish red muscle SR resembles mammalian slow fibres in that the pump protein's molecular weight is not the same as the white. Unlike mammalian SR, vesicles isolated from trout red muscle or not stimulated by commercially available cAMP dependent protein kinases. 2. The microsomal pellet of muscle is generally contaminated with mitochondrial fragments and sarcolemmal vesicles. Pure sarcoplasmic reticulum fractions have been obtained from plaice 2+ 2+ muscle and the characteristics of the Ca2+ ATPase and Ca2+ uptake studied. The protein composition of the vesicles, the dependence on Mg2+, Ca2+, K+ and ADP are demonstrated to be similar to that of rabbit muscle. A comparison of the levels of the phosphorylated enzyme intermediate with those obtained by other workers shows that the pump protein concentration is similar to rabbit fast skeletal muscle. 3. The effect of evolutionary temperature adaptation on the sarcoplasmic reticulum of different species of fish has been examined. The Ca2+ ATPase shows an inverse h correlation with the cell temperature of the species at O°C, and this difference is reflected in the relative rates of Ca2+ uptake. Activation enthalpy increases with increasing environmental temperature, while activation entropy goes from negative values in .the cold adapted to positive values in the hot adapted species. Unlike other enzyme systems, the activation energy shows no correlation with temperature. Acclimation to seasonal temperature changes has also been studied. Unlike adaptation on evolutionary time scales, acclimation does not affect the activation entropy of the ATPase, and there is no significant difference in the rates of ATP hydrolysis. It is concluded that the mechanisms of compensation are different in adaption to evolutionary and seasonal temperature changes. Evidence for acclimation to low temperatures involving an increase in the amount of sarcoplasmic reticulum is reviewed. 4. The enzyme-substrate affinity has been monitored by measuring the KCa of the Ca2+ ATPase at different temperatures for four different species of teleost. As with the Vmax estimations, compensatory changes are shown in the ATPase. KCa values, estimated at O°C are found to be inversely related Ca. to the animal's cell temperature. When estimated at that temperature, the values are similar. These results are discussed in relation to the observed prepondence of parvalbumins in fish muscle, and a possible role of the parvalbumins is considered. 5. In even the purest of SR preparations, i.e. those with no contaminating marker enzymes, a Ca2+ independent ATPase activity can be demonstrated. Unlike the Ca2+-ATPase the Ca2+ -independent ATPase activity is not related to habitat temperature, and the activation entropy is not proportional to cell temperature. As shown in the, rabbit, incubation of the SR in the presence of 0.1% Triton X-100 converts the basal ATPase activity in all except the lightest fractions to Ca2+ dependence. It is suggested that the Ca2+ independent ATPase represents a form of the pump protein uncoupled from Ca2+ transport, with the two forms of the ATPase in thermal equilibrium. Supportive evidence is provided for this theory. The ratio of Ca2+ dependent to total ATPase is temperature dependent, increasing to maximal value at and above the animal's cell temperature. For example, the ratio of approximately 0.25 at O°C in Tilapia mariae (a tropical species), increasing to 0.85 at 25°0. In contrast, the ratio for Myoxocephalus scorpius (North Sea) is only slightly affected by assay temperature and remains at about 0.95 throughout the range O - 33°C. The activation energy for the conversion has been estimated for two species and compared with that of rabbit. It is possible that the contribution of the activation energy for the conversion may account for the poor correlation of the DeltaG# of the Ca2+-dependent ATPase with environment temperature

The effect of maternal iron deficiency on zinc and copper levels and on genes of zinc and copper metabolism during pregnancy in the rat

Fe deficiency is relatively common in pregnancy and has both short- and long-term consequences. However, little is known about the effect on the metabolism of other micronutrients. A total of fifty-four female rats were fed control (50 mg Fe/kg) or Fe-deficient diets (7·5 mg/kg) before and during pregnancy. Maternal liver, placenta and fetal liver were collected at day 21 of pregnancy for Cu and Zn analysis and to measure expression of the major genes of Cu and Zn metabolism. Cu levels increased in the maternal liver (P=0·002) and placenta (P=0·018) of Fe-deficient rats. Zn increased (P&lt;0·0001) and Cu decreased (P=0·006) in the fetal liver. Hepatic expression of the Cu chaperones antioxidant 1 Cu chaperone (P=0·042) and cytochrome c oxidase Cu chaperone (COX17, P=0·020) decreased in the Fe-deficient dams, while the expression of the genes of Zn metabolism was unaltered. In the placenta, Fe deficiency reduced the expression of the chaperone for superoxide dismutase 1, Cu chaperone for superoxide dismutase (P=0·030), ceruloplasmin (P=0·042) and Zn transport genes, ZRT/IRT-like protein 4 (ZIP4, P=0·047) and Zn transporter 1 (ZnT1, P=0·012). In fetal liver, Fe deficiency increased COX17 (P=0·020), ZRT/IRT-like protein 14 (P=0·036) and ZnT1 (P=0·0003) and decreased ZIP4 (P=0·004). The results demonstrate that Fe deficiency during pregnancy has opposite effects on Cu and Zn levels in the fetal liver. This may, in turn, alter metabolism of these nutrients, with consequences for development in the fetus and the neonate.</p

Processes underlying the nutritional programming of embryonic development by iron deficiency in the rat

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Maternal iron status in early pregnancy and birth outcomes : insights from the Baby's Vascular health and Iron in Pregnancy study

Date of Acceptance: 16/03/2015 Acknowledgements N. A. A. was funded by a Wellcome Trust Research Training Fellowship (WT87789). H. J. M. and H. E. H. are supported by the Scottish Government’s Rural and Environment Science and Analytical Services. N. A. B. S. is supported by Cerebra. The authors’ contributions are as follows: N. A. A. was responsible for organising the study conduct, data collection and database management, performed the statistical analysis, interpreted the results and drafted the paper. N. A. A., N. A. B. S., J. E. C., H. J. M. and D. C. G. contributed to the study concept and design, and interpretation of results. H. J. M. and H. E. H. analysed the laboratory samples. J. E. C. and D. C. G. provided advice on statistical strategy and analysis. All authors have fully participated in the reporting stage and have critically reviewed and approved the final draft of the paper. The authors declare no conflict of interestPeer reviewedPublisher PD

The effect of feeding a low iron diet prior to and during gestation on fetal and maternal iron homeostasis in two strains of rat

Background Iron deficiency anaemia during pregnancy is a global problem, with short and long term consequences for maternal and child health. Animal models have demonstrated that the developing fetus is vulnerable to maternal iron restriction, impacting on postnatal metabolic and blood pressure regulation. Whilst long-term outcomes are similar across different models, the commonality in mechanistic events across models is unknown. This study examined the impact of iron deficiency on maternal and fetal iron homeostasis in two strains of rat. Methods Wistar (n=20) and Rowett Hooded Lister (RHL, n=19) rats were fed a control or low iron diet for 4 weeks prior to and during pregnancy. Tissues were collected at day 21 of gestation for analysis of iron content and mRNA/protein expression of regulatory proteins and transporters. Results A reduction in maternal liver iron content in response to the low iron diet was associated with upregulation of transferrin receptor expression and a reduction in hepcidin expression in the liver of both strains, which would be expected to promote increased iron absorption across the gut and increased turnover of iron in the liver. Placental expression of transferrin and DMT1+IRE were also upregulated, indicating adaptive responses to ensure availability of iron to the fetus. There were considerable differences in hepatic maternal and fetal iron content between strains. The higher quantity of iron present in livers from Wistar rats was not explained by differences in expression of intestinal iron transporters, and may instead reflect greater materno-fetal transfer in RHL rats as indicated by increased expression of placental iron transporters in this strain. Conclusions Our findings demonstrate substantial differences in iron homeostasis between two strains of rat during pregnancy, with variable impact of iron deficiency on the fetus. Whilst common developmental processes and pathways have been observed across different models of nutrient restriction during pregnancy, this study demonstrates differences in maternal adaptation which may impact on the trajectory of the programmed response

Safety of the extension of use of plant sterol esters as a novel food pursuant to Regulation (EU) 2015/2283

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How reliable and robust are current biomarkers for copper status?

Cu is an essential nutrient for man, but can be toxic if intakes are too high. In sensitive populations, marginal over- or under-exposure can have detrimental effects. Malnourished children, the elderly, and pregnant or lactating females may be susceptible for Cu deficiency. Cu status and exposure in the population can currently not be easily measured, as neither plasma Cu nor plasma cuproenzymes reflect Cu status precisely. Some blood markers (such as ceruloplasmin) indicate severe Cu depletion, but do not inversely respond to Cu excess, and are not suitable to indicate marginal states. A biomarker of Cu is needed that is sensitive to small changes in Cu status, and that responds to Cu excess as well as deficiency. Such a marker will aid in monitoring Cu status in large populations, and will help to avoid chronic health effects (for example, liver damage in chronic toxicity, osteoporosis, loss of collagen stability, or increased susceptibility to infections in deficiency). The advent of high-throughput technologies has enabled us to screen for potential biomarkers in the whole proteome of a cell, not excluding markers that have no direct link to Cu. Further, this screening allows us to search for a whole group of proteins that, in combination, reflect Cu status. The present review emphasises the need to find sensitive biomarkers for Cu, examines potential markers of Cu status already available, and discusses methods to identify a novel suite of biomarker