Dietary Zinc Levels Research Articles

Zinc Deficiency Is associated With Depressive Symptoms-Results From the Berlin Aging Study II.

Zinc plays an important role for behavioral and mental function, maintaining the correct functions of intracellular signal transduction, cellular and trans-membrane transport, protein synthesis, and antioxidant system. We investigated both dietary zinc intake and plasma zinc levels and the correlation with depressive symptoms in a large sample of community-dwelling old. One thousand five hundred fourteen older people (aged 60-84 years, 772 women) from the Berlin Aging Study II were included. Zinc intake was assessed by the EPIC Food Frequency Questionnaire. Plasma zinc levels were assessed with atomic-absorption spectrophotometry. Depressive symptoms were assessed with the "Center for Epidemiological Studies Depression Scale" and the "Geriatric Depression Scale." Zinc deficiency in blood plasma was found in 18.7% of participants, and depressive symptoms in 15.7%. Participants with depressive symptoms had lower energy-adjusted zinc intake (median 11.1 vs 11.6 µmol/L; p = .048) and lower plasma zinc levels (median 12.2 vs12.3 mg/dL; p = .037). Even after adjustment for known predictors of depression, plasma zinc deficiency remained significantly associated with depressive symptoms (odds ratio: 1.490, 95% confidence interval: 1.027-2.164; p = .036). In the multiple logistic regression model stratified by sex, we found that plasma zinc deficiency was strongly associated with a higher risk for depressive symptoms in women (odds ratio: 1.739, 95% confidence interval: 1.068-2.833; p = .026). Plasma zinc deficiency was common in our old study population. An increase in dietary zinc and higher plasma zinc levels may reduce the risk of depressive symptoms. A screening for reduced dietary zinc intake or plasma zinc deficiency might be beneficial in older people at risk of depressive symptoms.

Rice NICOTIANAMINE SYNTHASE 2 expression improves dietary iron and zinc levels in wheat

Key messageIron and zinc deficiencies negatively impact human health worldwide. We developed wheat lines that meet or exceed recommended dietary target levels for iron and zinc in the grains. These lines represent useful germplasm for breeding new wheat varieties that can reduce iron and zinc deficiency-associated health burdens in the affected populations.Micronutrient deficiencies, including iron and zinc deficiencies, have negative impacts on human health globally. Iron-deficiency; anemia affects nearly two billion people worldwide and is the cause of reduced cognitive development, fatigue and overall low productivity. Similarly, zinc deficiency causes stunted growth, decreased immunity and increased risk of respiratory infections. Biofortification of staple crops is a sustainable and effective approach to reduce the burden of health problems associated with micronutrient deficiencies. Here, we developed wheat lines expressing rice NICOTIANAMINE SYNTHASE 2 (OsNAS2) and bean FERRITIN (PvFERRITIN) as single genes as well as in combination. NAS catalyzes the biosynthesis of nicotianamine (NA), which is a precursor of the iron chelator deoxymugeneic acid (DMA) required for long distance iron translocation. FERRITIN is important for iron storage in plants because it can store up to 4500 iron ions. We obtained significant increases of iron and zinc content in wheat grains of plants expressing either OsNAS2 or PvFERRTIN, or both genes. In particular, wheat lines expressing OsNAS2 greatly surpass the HarvestPlus recommended target level of 30 % dietary estimated average requirement (EAR) for iron, and 40 % of EAR for zinc, with lines containing 93.1 µg/g of iron and 140.6 µg/g of zinc in the grains. These wheat lines with dietary significant levels of iron and zinc represent useful germplasm for breeding new wheat varieties that can reduce micronutrient deficiencies in affected populations.

Effect of dietary zinc on the growth and metabolic enzyme activities of golden mahseer (Tor putitora) fry

The golden mahseer (Tor putitora) is an important and high valued sport and food fish of national and international importance. Therefore for promotion of golden mahseer, proper mineral supplementation in early developmental stages is very important. The present study evaluated the effects of dietary zinc on growth, survivaland physiological response of Tor putitora fry. One thousand eight hundred fry (avg.wt 54.35±3.09 mg) were randomly distributed into 6 treatment groups with triplicates each. Six iso-nitrogenous (40±0.02% to 41.44±0.01% crude protein) semi-purified diets were prepared with graded levels of dietary zinc. Zinc sulphate was added as the dietary zinc source to the basal diet. The results indicated that specific growth rate (SGR) was of value 2.52 ±0.23 gm of T. putitora fry which increased with dietary zinc levels up to a concentration of 40 mg Zn Kg-1 in diet. The zinc dependent metabolic enzymes and antioxidant enzymes was also observed to be highest in groups supplemented with 40 mg zinc/kg feed. The overall results of the present study suggest the efficacy of dietary zinc on growth, survival and physiological response of golden mahseer fry in order to garner the possibility of establishing the species to commercial aquaculture.

Effect of different levels of dietary zinc, manganese, and copper from organic or inorganic sources on performance, bacterial chondronecrosis, intramuscular collagen characteristics, and occurrence of meat quality defects of broiler chickens

The aim of the experiment was to assess the effects of 2 dietary levels of trace minerals (TM) zinc, manganese, and copper either from organic (OTM) or inorganic (ITM) sources on broiler performance, carcass traits, intramuscular collagen (IMC) properties, occurrence of hock burns (HB), foot pad dermatitis (FPD), femoral and tibia head necrosis, and breast muscle abnormalities (white striping, WS; wooden breast, WB; poor cohesion, PC). A total of 3,600 one-day-old male chicks were randomly assigned to one of 4 dietary treatments in a 2 × 2 factorial arrangement (9 replicates of 100 birds/dietary treatment). Birds were slaughtered at 31 (thinning) and 51d of age. Body weight, daily weight gain (DWG), feed intake, feed conversion rate (FCR), and mortality were determined. A significant effect of the source of TM supplementation was found only in 51-day-old chickens. Birds of the OTM groups were heavier (P < 0.05), with a higher (P < 0.05) DWG and a better FCR (P < 0.05) compared with those of the ITM groups. OTM significantly reduced the lesion scores of femoral head (P = 0.004) and total leg (femur + tibia, P = 0.02) compared to ITM, which is mainly caused by the reduction of the percentages of femoral head transitional degeneration (FHT, P = 0.04) and femoral head necrosis (FHN, P = 0.07). Carcass traits were similar among the experimental groups. No alleviating effect of TM administration on the incidence of FPD and HB in 31- and 51-day-old chickens was found. Similarly, the occurrence and the degrees of WS and WB in 51-day-old chickens was affected neither by the doses nor by the source of TM supplied. IMC characteristics of broiler pectoral muscle were not affected (P > 0.05) by the different sources and doses of TM administrated.

Extensive Literature Search on the ‘Effects of Copper intake levels in the gut microbiota profile of target animals, in particular piglets’

Extensive Literature Search on the ‘Effects of Copper intake levels in the gut microbiota profile of target animals, in particular piglets’

The protective effects of dietary zinc on dietary copper toxicity in large yellow croaker Larimichthys croceus

A study was carried out to test the responses of juvenile large yellow croaker to dietary copper and zinc intakes. Four experimental diets (coded as: −Cu−Zn, −Cu+Zn, +Cu−Zn and +Cu+Zn) were formulated containing two levels of Cu (4 and 24mg/kg diet) and two levels of Zn (0 and 120mg/kg diet), and each diet was fed to fish in triplicate for 10weeks. Fish fed with +Cu diets (+Cu−Zn and +Cu+Zn) had lower final body weight, weight gain, superoxide dismutase, catalase, glutathione peroxidase (GPX), 6-phosphogluconate dehydrogenase, malic enzyme, isocitrate dehydrogenase and fatty acid synthase activities than fish fed with −Cu diets (−Cu−Zn and −Cu+Zn), but fish fed with +Cu diets had higher liver Cu, muscle Cu and thiobarbituric acid reactive substance (TBARS) contents, and lipoprotein lipase (LPL) activity than fish fed with −Cu diets. By contrast, fish fed with +Zn diets (+Cu+Zn and −Cu+Zn) had greater GPX activities than fish fed with −Zn diets (+Cu−Zn and −Cu−Zn), but fish fed with +Zn diets had lower TBARS content and LPL activity than fish fed with −Zn diets. This study indicated that high copper intake reduced growth of juvenile large yellow croaker, inhibited activities of antioxidant enzymes and lipid synthetases. The high levels of dietary zinc could mitigate the adverse effect of high copper toxicity on fish performance. Statement of relevanceThis study will be useful in developing mineral-balanced diets for intensive culture of large yellow croaker.

297 Effects of dietary zinc source and level on nursery pig performance

Citation: Jordan, K. E., Gourley, K. M., Tokach, M. D., Goodband, R. D., Dritz, S. S., DeRouchey, J. M., . . . Usry, J. L. (2016). Effects of dietary zinc source and level on nursery pig performance. Journal of Animal Science, 94, 139-139. doi:10.2527/msasas2016-297

Development, validity, and reliability of a food frequency questionnaire for antioxidants in elderly Iranian people.

Background:The food frequency questionnaire (FFQ), as a way to assess the dietary intake in comparison with other methods, is easier to analyze and takes less time and is less costly. Our aim in this study was to develop and validate an FFQ for estimating the intakes of selected antioxidants in elderly Iranian people.Materials and Methods:A total of 185 elderly people were randomly selected. Three-day food records were completed by the subjects and collected every 2 months and dietary intake levels of zinc, selenium, carotenes and vitamins C and E were estimated. Based on the food records data, geographic location, and age, an FFQ was designed to estimate antioxidant intakes during 1 year. In addition, for controlling energy intake, 2-day food records were also collected with the food frequency questionnaire. To assess the reliability, 40 individuals were asked to complete the FFQ twice with an interval of 3 months in between.Results:Intraclass correlation coefficient (ICC) between the two FFQs for antioxidant C, antioxidant E, carotene, selenium, and zinc were 0.62, 0.47, 0.51, 0.54, and 0.58, respectively (P < 0.05). In addition, Pearson correlation coefficients between the FFQ and the food records, after controlling energy for vitamin C, vitamin E, carotene, selenium, and zinc, were 0.46, 0.48, 0.38, 0.55, and 0.47 respectively (P < 0.001).Conclusion:According to the results of this study, considering the fact that the FFQ was designed for the elderly and the special conditions (patience, memory, etc.) and vulnerability of this age group, the questionnaire is relatively valid and reliable to use.

Effects of Dietary Zinc Source and Level on Mammary Epithelia and Dairy Food Chemistry

Effects of Dietary Zinc Source and Level on Mammary Epithelia and Dairy Food Chemistry

Dietary zinc supplementation increased TNFα and IL1β-induced RANKL expression, resulting in a decrease in bone mineral density in rats.

We investigated the effect of dietary zinc supplementation on bone metabolism in rats. Four-week-old male Wistar rats were fed a 30.0 mg zinc/kg diet (C), a 300.0 mg zinc/kg diet (HZ) or a 3,000.0 mg zinc/kg diet (EZ) for 4 weeks. The zinc content of the femur gradually increased in accordance with the gradual increase in the dietary zinc level. Although the mRNA expression of zinc transporters in bone did not differ between the groups, the mRNA expression of metallothioneins was increased in the HZ and EZ groups compared to the C group. Moreover, the bone mineral density was significantly decreased in the HZ and EZ groups compared to the C group. Furthermore, the mRNA expression of tumor necrosis factor α, Interleukin-1β and osteoclastogenesis-related genes such as receptor for activator of nuclear factor-κB (NF-κB) ligand, tumor necrosis factor receptor-associated factor 6, and nuclear factor of activated T cells cytoplasmic 1 was significantly increased in the HZ and EZ groups compared to the C group. These findings suggested that dietary zinc supplementation reduced bone mineral density through the promotion of bone resorption via an increase in the expression of receptor for activator of NF-κB ligand induced by tumor necrosis factor α and Interleukin-1β.

Effects of supplemental zinc source and level on antioxidant ability and fat metabolism-related enzymes of broilers

The objective of the present study was to investigate the effects of dietary supplemental Zinc (Zn) source and level on antioxidant ability and fat metabolism-related enzymes of broilers. Dietary treatments included the Zn-unsupplemented corn-soybean meal basal diet (control) and basal diets supplemented with 60, 120, or 180 mg Zn/kg as Zn sulfate, Zn amino acid chelate with a weak chelation strength of 6.5 quotient of formation (Qf) (11.93% Zn) (Zn-AA W), Zn proteinate with a moderate chelation strength of 30.7 Qf (13.27% Zn) (Zn-Pro M), or Zn proteinate with an extremely strong chelation strength of 944.0 Qf (18.61% Zn) (Zn-Pro S). The results showed that dietary supplemental Zn increased (P < 0.01) Zn contents in the liver, breast, and thigh muscles of broilers, and up-regulated mRNA expressions of copper and Zn containing superoxide dismutase (CuZnSOD) and metallothioneins (MT) in the liver (P < 0.01) and thigh muscle (P < 0.05), and also enhanced (P < 0.05) CuZnSOD activities in the breast and thigh muscles, which exerted antioxidant ability and a decreased malondialdehyde (MDA) level in the liver (P < 0.01) and breast and thigh muscles (P < 0.05) of broilers. Furthermore, supplemental Zn increased activities of malate dehydrogenase (MDH) and lipoprotein lipase (LPL) in the abdominal fat (P < 0.05), and fatty acid synthetase (FAS) and LPL in the liver (P < 0.01), which were accompanied with up-regulation (P < 0.01) of the mRNA expressions levels of these enzymes in the abdominal fat and liver of broilers. Dietary Zn source, and an interaction between Zn source and level, had no effects on any measurements. It is concluded that dietary Zn supplementation improved Zn status and resulted in promoting antioxidant ability and activities and gene expressions of fat metabolism-related enzymes of broilers regardless of Zn source and level, and the addition of 60 mg Zn/kg to the corn-soybean meal basal diet (a total dietary Zn of approximately 90 mg/kg) was appropriate for improving the above aspects of broilers.

Copper, zinc and iron levels in infants and their mothers during the first year of life: a prospective study.

BackgroundEssential micronutrients are important for maintenance of life. Deficiency of micronutrients is more likely to be encountered in children, and women studies are required to investigate the status of micronutrients in children and women. This study aimed to longitudinally evaluate changes in zinc, copper, and iron levels in breastfed infants and their mothers during the first year of life.MethodsSerum and hair samples were obtained from 35 healthy breastfed infants (51 % males, 49 % females) and their mothers 2, 6, and 12 months after delivery. All of the samples were assessed using an atomic absorption spectrophotometer. Serum iron levels were determined by a Roche/Hitachi/Modular analyzer. Statistical analyses were performed using SPSS-PC (Version 21.00) software.ResultsHair zinc (p < 0.05) and serum iron (p < 0.001) levels of infants were significantly decreased towards the end of the first year. Infants’ serum copper levels were increased towards the end of the first year. Maternal serum and hair copper levels and serum iron levels were significantly decreased towards the end of the first year. There were no significant correlations between dietary zinc, copper, iron intake, and trace element levels of infants and their mothers.ConclusionsInfants’ hair zinc levels, maternal and infants’ hair copper levels, and infants’ and maternal serum iron levels declined towards the end of the first year. Infants need more zinc after 6 months of age. Infants’ and mothers’ daily iron intake was less than the recommended intake.

A role for dZIP89B in Drosophila dietary zinc uptake reveals additional complexity in the zinc absorption process

Dietary zinc is the principal source of zinc in eukaryotes, with its uptake and distribution controlled by a complex network of numerous membrane-spanning transport proteins. Dietary absorption is achieved by members of the SLC39A (ZIP) gene family, which encode proteins that are generally responsible for the movement of zinc into the cytosol. ZIP4 is thought to be the primary mammalian zinc uptake gene in the small intestine, with mutations in this gene causing the zinc deficiency disease Acrodermatitis enteropathica. In Drosophila, dual knockdown of the major dietary zinc uptake genes dZIP42C.1 (dZIP1) and dZIP42C.2 (dZIP2) results in a severe sensitivity to zinc-deficient media. However, the symptoms associated with ZIP4 loss can be reversed by zinc supplementation and dZIP42C.1 and 2 knockdown has minimal effect under normal dietary conditions, suggesting that additional pathways for zinc absorption exist in both mammals and flies. This study provides evidence that dZIP89B is an ideal candidate for this role in Drosophila, encoding a low-affinity zinc uptake transporter active in the posterior midgut. Flies lacking dZIP89B, while viable and apparently healthy, show indications of low midgut zinc levels, including reduced metallothionein B expression and compensatory up-regulation of dZIP42C.1 and 2. Furthermore dZIP89B mutants display a dramatic resistance to toxic dietary zinc levels which is abrogated by midgut-specific restoration of dZIP89B activity. We postulate that dZIP89B works in concert with the closely related dZIP42C.1 and 2 to ensure optimal zinc absorption under a range of dietary conditions.

Intracellular zinc in insulin secretion and action: a determinant of diabetes risk?

Zinc is an important micronutrient, essential in the diet to avoid a variety of conditions associated with malnutrition such as diarrhoea and alopecia. Lowered circulating levels of zinc are also found in diabetes mellitus, a condition which affects one in twelve of the adult population and whose treatments consume approximately 10 % of healthcare budgets. Zn2+ ions are essential for a huge range of cellular functions and, in the specialised pancreatic β-cell, for the storage of insulin within the secretory granule. Correspondingly, genetic variants in the SLC30A8 gene, which encodes the diabetes-associated granule-resident Zn2+ transporter ZnT8, are associated with an altered risk of type 2 diabetes. Here, we focus on (i) recent advances in measuring free zinc concentrations dynamically in subcellular compartments, and (ii) studies dissecting the role of intracellular zinc in the control of glucose homeostasis in vitro and in vivo. We discuss the effects on insulin secretion and action of deleting or over-expressing Slc30a8 highly selectively in the pancreatic β-cell, and the role of zinc in insulin signalling. While modulated by genetic variability, healthy levels of dietary zinc, and hence normal cellular zinc homeostasis, are likely to play an important role in the proper release and action of insulin to maintain glucose homeostasis and lower diabetes risk.

Effects of dietary zinc supplementation during a forced molt on subsequent hen performance and egg quality.

A total of 200 Hy- Line Brown commercial layer hens (64) weeks of age, were used in&#x0D; this study to investigate the impacts of different dietary zinc supplementation during a&#x0D; forced molt on subsequent hen performance and egg quality. The hens were randomly&#x0D; divided into (5) treatment groups of 40 hens each treatment. There were four replicate&#x0D; cages per treatment. The hens in the treatment 1 (control) were fed a layer ration&#x0D; containing 0 ppm ZnO, water and feed were provided ad libitum and received 16 hours&#x0D; of light/day, treatment (2) were fed a layer ration containing 28000 ppm Zn as zinc oxide&#x0D; for 11 days, treatment (3) 37000 ppm ZnO for 9 days, treatment (4) 46000 ppm ZnO for&#x0D; 7 days, and treatment (5)on-again, off-again program (ON-OFF).The experimental&#x0D; period was divided into seven periods (1) 64-66, (2) 67-69, (3) 70-72, (4) 73-75, (5) 76-&#x0D; 78, (6) 79-81, (7) 82-84 weeks. The results indicated that different levels of dietary zinc&#x0D; were improved Hen Day (H.D) egg production and egg weight at periods 70-72, 73-75,&#x0D; 76-78, 79-81, 82-84 weeks, except treatment 37000 ppm ZnO in period 70-72 was&#x0D; reduced in both egg production and egg weight, yolk and white weight improved also in&#x0D; these five periods above, feed intake was improved in two periods 70-72 and 73-75&#x0D; weeks, feed conversion ratio was decreased in two periods 73-75 and 76-78 weeks,&#x0D; compared to both control and ON-OFF program. Haugh unit was improved in dietary&#x0D; zinc treatments and ON-OFF program in all periods except period 64-66 weeks&#x0D; compared to control. The percentage of weight loss was increased in the period 64-67&#x0D; weeks for all treatments except control. Different dietary zinc supplementation was&#x0D; increased the concentration of zinc in yolk from 10.20 ppm (control) to 32.84, 29.61 and&#x0D; 51.08 and, white from 3.50 ppm (control) to 5.96, 5.90 and 6.37 ppm for 28000, 37000&#x0D; and 46000 ppm during fed them with Zn for 11, 9 and 7 days, respectively, but the&#x0D; concentration of zinc in yolk and white was reduced week by week after following the&#x0D; refeeding of a control diet and was normally by week 6.

Effects of Dietary Copper and Zinc Supplementation on Growth Performance, Tissue Mineral Retention, Antioxidant Status, and Fur Quality in Growing-Furring Blue Foxes (Alopex lagopus).

A 4×2 factorial experiment with four supplemental levels of copper (0, 20, 40, or 60 mg copper per kg dry matter) from copper sulfate and two supplemental levels of zinc (40 or 200 mg zinc per kg dry matter) from zinc sulfate was conducted to investigate the effects of dietary copper and zinc supplementation on growth performance, tissue mineral retention, antioxidant status, and fur quality in growing-furring blue foxes. One hundred and twenty healthy 15-week-old male blue foxes were randomly allocated to eight dietary treatments with 15 replicates per treatment for a 70-day trial from mid-September to pelting in December. The average daily gain and feed conversion ratio were increased with copper supplementation in the first 35 days as well as the overall period (P<0.05). In addition, copper supplementation tended to increase feed intake during the first 35 days (P<0.10). Diets supplemented with 200 mg/kg zinc did not affect body gain (P>0.10) and feed intake (P>0.10) but improved feed conversion (P<0.05) compared with those supplemented 40 mg/kg zinc throughout the experiment. No copper×zinc interaction was observed for growth performance except that a tendency (P=0.09) was found for feed intake in the first 35 days. Supplementation of copper or zinc improved crude fat digestibility (P<0.01) but had no effects on the digestibility of other nutrients. Fecal copper was increased with both copper (P<0.01) and zinc addition (P<0.05). However, fecal zinc was affected only by dietary zinc addition (P<0.01). Mineral contents in serum and kidney were not affected by dietary treatments (P>0.05). However, the level of copper in the liver was increased with copper supplementation (P<0.05) and tended to decrease with zinc supplementation (P=0.08). Dietary zinc addition tended to increase the activity of alkaline phosphatase (P=0.07). The activities of copper-zinc superoxide dismutase and catalase tended to increase by copper (P=0.08) and zinc addition (P=0.05). Moreover, a copper×zinc interaction was observed for catalase in the experiment (P<0.05). Serum malondialdehyde concentration decreased with the increasing of dietary copper and zinc levels (P<0.05). The activity of glutathione peroxidase tended to increase by copper addition (P=0.09). For fur quality, foxes fed diets supplemented with high copper had larger skin length and darker pelts than those fed the basal diet without copper addition (P<0.05). In conclusion, this study demonstrated that dietary copper and zinc supplementation can improve growth by increasing feed intake and improving fat digestibility. Additionally, copper and zinc can enhance the antioxidant capacity of blue foxes. This study also indicates that additional zinc up to 200 mg/kg did not exert significant adverse effects on the copper metabolism of growing-furring blue foxes.

Impact of high dietary zinc on zinc accumulation, enzyme activity and proteomic profiles in the pancreas of piglets

The exocrine pancreas plays an important role in zinc homeostasis. Feeding very high (2000–3000mgzinc/kg diet) levels of zinc oxide to piglets for short periods is a common practice in the swine industry to improve performance and prevent diseases. The impact on pancreatic function and possible side effects during long-term feeding of high dietary zinc levels are still poorly understood. A total of 54 weaned piglets were either fed with low (57mg/kg, LZn), normal (164mg/kg, NZn) or high (2425mg/kg, HZn) zinc concentration in the diets. After 4 weeks of feeding, ten piglets per treatment were euthanized and pancreas samples were taken. Tissue zinc concentration and metallothionein abundance was greater with HZn compared with NZn and LZn (P<0.05). Similarly, activity of α-amylase, lipase, trypsin and chymotrypsin was higher with HZn as compared with NZn and LZn diets (P<0.05), whereas elastase activity was unchanged. Total trolox equivalent antioxidative capacity of pancreas tissue was higher with HZn diets compared with the other treatments (P<0.05). Pancreatic protein profiles of NZn and HZn fed piglets were obtained by 2D-DIGE technique and revealed 15 differentially expressed proteins out of 2100 detected spots (P<0.05). The differentially expressed proteins aldose reductase, eukaryotic elongation factor II and peroxiredoxin III were confirmed by immunoblotting. Identified proteins include zinc finger-containing transcription factors and proteins mainly associated with oxidative stress response and signal transduction in HZn compared with NZn pigs. Histologic examination however showed no morphologic changes. The results suggest that long-term supply of very high dietary zinc increases zinc and metallothionein concentration, and digestive enzyme activity, but also triggers oxidative stress reactions in the pancreas of young pigs. The data provide new insights into pancreatic function under outbalanced zinc homeostasis.

A modular system of DNA enhancer elements mediates tissue-specific activation of transcription by high dietary zinc in C. elegans.

Zinc is essential for biological systems, and aberrant zinc metabolism is implicated in a broad range of human diseases. To maintain homeostasis in response to fluctuating levels of dietary zinc, animals regulate gene expression; however, mechanisms that mediate the transcriptional response to fluctuating levels of zinc have not been fully defined. Here, we identified DNA enhancer elements that mediate intestine-specific transcriptional activation in response to high levels of dietary zinc in C. elegans. Using bioinformatics, we characterized an evolutionarily conserved enhancer element present in multiple zinc-inducible genes, the high zinc activation (HZA) element. The HZA was consistently adjacent to a GATA element that mediates expression in intestinal cells. Functional studies using transgenic animals demonstrated that this modular system of DNA enhancers mediates tissue-specific transcriptional activation in response to high levels of dietary zinc. We used this information to search the genome and successfully identified novel zinc-inducible genes. To characterize the mechanism of enhancer function, we demonstrated that the GATA transcription factor ELT-2 and the mediator subunit MDT-15 are necessary for zinc-responsive transcriptional activation. These findings define new mechanisms of zinc homeostasis and tissue-specific regulation of transcription.

Determination Content of Zinc Element in Natural Huazi Mushroom by ICP-AES

Zinc is an essential trace element, zinc content in human body is 1.4~2.3g, is widely distributed in various tissues, including skeletal and skin are more, the nutritional status of zinc content in hair Znn reflect the long-term supply of dietary zinc level and human zinc. Using the high pressure nitrifying pot method and wet method and treatment of samples were determined in natural Huazi Mushroom samples Zn element content. High pressure nitrifying pot method relative standard deviation of Zn element is 5.82%; Wet method to determine the relative standard deviation of Zn elementt is 4.81%. Visible high pressure nitrifying pot method and treatment of samples of precision of the measuring precision and wet processing samples are relatively low. By comparison, high pressure nitrifying pot method specific humidity method to deal with the sample good measuring precision, higher accuracy, and the measurement process to save time.

The DAF-16 FOXO transcription factor regulates natc-1 to modulate stress resistance in Caenorhabditis elegans, linking insulin/IGF-1 signaling to protein N-terminal acetylation.

The insulin/IGF-1 signaling pathway plays a critical role in stress resistance and longevity, but the mechanisms are not fully characterized. To identify genes that mediate stress resistance, we screened for C. elegans mutants that can tolerate high levels of dietary zinc. We identified natc-1, which encodes an evolutionarily conserved subunit of the N-terminal acetyltransferase C (NAT) complex. N-terminal acetylation is a widespread modification of eukaryotic proteins; however, relatively little is known about the biological functions of NATs. We demonstrated that loss-of-function mutations in natc-1 cause resistance to a broad-spectrum of physiologic stressors, including multiple metals, heat, and oxidation. The C. elegans FOXO transcription factor DAF-16 is a critical target of the insulin/IGF-1 signaling pathway that mediates stress resistance, and DAF-16 is predicted to directly bind the natc-1 promoter. To characterize the regulation of natc-1 by DAF-16 and the function of natc-1 in insulin/IGF-1 signaling, we analyzed molecular and genetic interactions with key components of the insulin/IGF-1 pathway. natc-1 mRNA levels were repressed by DAF-16 activity, indicating natc-1 is a physiological target of DAF-16. Genetic studies suggested that natc-1 functions downstream of daf-16 to mediate stress resistance and dauer formation. Based on these findings, we hypothesize that natc-1 is directly regulated by the DAF-16 transcription factor, and natc-1 is a physiologically significant effector of the insulin/IGF-1 signaling pathway that mediates stress resistance and dauer formation. These studies identify a novel biological function for natc-1 as a modulator of stress resistance and dauer formation and define a functionally significant downstream effector of the insulin/IGF-1 signaling pathway. Protein N-terminal acetylation mediated by the NatC complex may play an evolutionarily conserved role in regulating stress resistance.