Zn In Milk Research Articles

A genetic variant in SLC30A2 causes breast dysfunction during lactation by inducing ER stress, oxidative stress and epithelial barrier defects

SLC30A2 encodes a zinc (Zn) transporter (ZnT2) that imports Zn into vesicles in highly-specialized secretory cells. Numerous mutations and non-synonymous variants in ZnT2 have been reported in humans and in breastfeeding women; ZnT2 variants are associated with abnormally low milk Zn levels and can lead to severe infantile Zn deficiency. However, ZnT2-null mice have profound defects in mammary epithelial cell (MEC) polarity and vesicle secretion, indicating that normal ZnT2 function is critical for MEC function. Here we report that women who harbor a common ZnT2 variant (T288S) present with elevated levels of several oxidative and endoplasmic reticulum (ER) stress markers in their breast milk. Functional studies in vitro suggest that substitution of threonine for serine at amino acid 288 leads to hyperphosphorylation retaining ZnT2 in the ER and lysosomes, increasing ER and lysosomal Zn accumulation, ER stress, the generation of reactive oxygen species, and STAT3 activation. These changes were associated with decreased abundance of zona occludens-1 and increased tight junction permeability. This study confirms that ZnT2 is important for normal breast function in women during lactation, and suggests that women who harbor defective variants in ZnT2 may be at-risk for poor lactation performance.

Energy dispersive X-ray fluorescence detection of heavy metals in Bangladesh cows' milk.

It is considered that cow's milk is almost complete food for human as it provides most of the micronutrients and macronutrients. The cow's milks are essential for the growth and development especially for children. The main compositions of cow's milk are protein, fat, carbohydrates, vitamins and minerals which are well defined. Presently, the study of micronutrients and toxic elements in cow's milk has been widely carried out particularly in the industrialized and polluted regions because of its possibility of contamination, and thereby health risk of the consumers. The elemental composition in local cow's milk samples in Bangladesh is not well studied yet. The present study was therefore aimed to determine the level of heavy metals (Cr, Ni, As, Cd, Hg, Pb, Mn, Cu, Zn and Fe) in cow's milk using EDXRF technique. Subsequently, the experimental data was used to calculate the human health risk through the intake of both powder and liquid cows’ milk available in Bangladesh. The results showed that powder milk contains significantly higher concentration of heavy metals than liquid milk samples. The HRI (health risk index) and HI (hazard index) values for most of the elements in all milk samples were within the safe limit (<1.0) or close to safe limit (≤1.0) with an exception of Hg. However, HRI value for Hg in powder milk samples for both children and adult showed a value higher than one (>1). MPI (metal pollution index) value for powder milk samples are very high compared to other type of milk samples analyzed in this study. Therefore, it has been suggested that heavy metal contamination through local powder milk samples might have significant negative impact (threat) on human health.

Determination of Heavy Metal Ions (As, Pb, Cd) and Zinc Mineral (Zn) in Humans and Cows Milk in Bitlis (Turkey)

Human�s milk and cow�s milk fed-infants, long before the mother is exposed heavy metals are potentially dangerous for both mother and baby. Concentrations of toxic heavy metals (Pb, Cd, As) and major nutritional trace element (Zn) which collected center Bitlis, Tatvan and various villages in the 75 volunteer nursing mothers received 6 months after the birth human�s milks and 75 cow milks were analyzed. This study was measured by Inductively Coupled Plasma-Mass Spectrometer. Work was measured in accredited laboratory. In the samples As and Cd were under detectable leves although Zn and Pb were measured. Survey conducted, Zn and Pb levels in the mother milk which collected Tatvan borough were determined the highest. The all metal levels in the mother milk and cow milk which collected Bitlis center higher than villages. Zn levels in the cow milks which collected Bitlis center the highest. As a results of analysis, the avarege values of the lead in the human milks respectively (Bitlis center, Tatvan borough and villages) were found 0.0003�0.00004 mg/kg, 0.00045�0.000052 mg/kg, 0.0002�0.00003 mg/kg; the avarege values of the zinc 3.2�0.64 mg/kg, 3.34�0.57 mg/kg, 2.5�0.37 mg/kg. The avarege values of the lead in the cow milks respectively (Bitlis center, Tatvan borough and villages) were found 0.002�0.0004 mg/kg, 0.003�0.0004 mg/kg, 0.001�0.0003 mg/kg; the avarege values of the zinc 3.7�0.51 mg/kg, 3.6�0.49 mg/kg, 3.0�0.41 mg/kg. As a results of analysis between groups weren�t found significant relationship (P]0.05).

Zinc concentrations in human milk and infant serum during the first six months of lactation

Normal supply of zinc to the newborn via milk is essential for normal development. Using ICP-OES, we analyzed changes in the level of Zn in milk and infant serum in the neonatal period (Day 1 and Day 28 post partum) and at 6 months after delivery, in the cohort of 60 mothers and exclusively breastfed babies. Zn level in the serum showed increase (significant at 6 months) during this period (mg/mL): Day 1: 0.52±0.12; Day 28: 0.59±0.19; 6 months: 0.68±0.28. The concentration of Zn in the milk showed an opposite (decreasing) trend during the follow up: Day 1: 4.70±1.74mg/L; Day 28: 2.65±1.06; 6 months: 0.46±0.36. A significant negative correlation was established between serum and milk [Zn] at day 28 (R=−0.338; p=0.008), whereas a positive correlation was found at 6 months between these parameters (R=0.306; p=0.018). There was no significant correlation between [Zn] in the milk and serum and infants' body mass, mothers' age and mass at delivery. The level of Zn in the milk at 6 months of lactation is not sufficient to meet the recommended values. This implies that in Serbian population, Zn supplementation might be needed in the later phase of lactation.

Atomic Absorption Spectrophotometery Detection of Heavy Metals in Milk of Camel, Cattle, Buffalo and Goat from Various Areas of Khyber- Pakhtunkhwa (KPK), Pakistan

The determination of the seven elements was performed by Perkin Elmer Atomic Absorption (AA) spectrophotometer. The present study highlights the importance of seven heavy metals residual concentration including Cd, Cr, Cu, Fe, Mn, Ni and Zn in milk of Camel, Cattle, Buffalo, Sheep and Goat from various areas of Khyber Pakhtunkhwa (KPK), Pakistan. It revealed that milk of camel comprising of high levels of Zn (5.150 ± 0.021 mg/kg), Mn (0.094 ± 0.003 mg/kg) and Fe (1.580 ± 0.530 mg/kg) with a definite correlation. In the milk of buffalo, high concentration of noxious heavy metals including Cu (0.223 ± 0.010 mg/kg) and Cd (0.117 ± 0.086 mg/kg) were found whereas in goat milk, high Ni (1.152 ± 0.045 mg/kg) and Cr (1.152 ± 0.045 mg/kg) was observed and detected. The analysis showed that camel and buffalo have similar high concentration of heavy metals. Overall results showed that milk of cattle shows higher concentration of Zn, Mn and Fe along with Buffalo.

Infrared Radiation Applied as a Heating Source in Milk Sample Preparation for the Determination of Trace Elements by Inductively Coupled Plasma-Optical Emission Spectroscopy

0 0 1 140 799 Federal University of Ceara 6 1 938 14.0 96 800x600 Normal 0 false false false PT-BR JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Table Normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman;} The use of infrared (IR) radiation as a heating source for milk sample preparation in trace element analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES) was investigated. Three strategies were studied: 1) a system that combined IR and microwave radiation (IR-MW); 2) partial digestion using only IR radiation (IR); and 3) partial digestion using IR radiation and vanadium pentoxide as a catalyst (IR-V 2 O 5 ). Precision and accuracy varied according to the element determined. The procedure using only IR radiation presented 15.1 ± 0.3 mg g -1 Ca, 0.76 ± 0.03 µg g -1 Cu, 217 ± 2 µg g -1 Fe, 14.8 ± 0.7 mg g -1 K, 1.17 ± 0.03 mg g -1 Mg, 4.41 ± 0.08 mg g -1 Na, 16.2 ± 0.1 mg g -1 P and 30.5 ± 0.6 µg g -1 Zn in non-fat milk. The use of IR radiation for sample preparation in trace element analysis is an easy to implement and a low-cost alternative for laboratories of food analysis that do not have a microwave available.

ASSESSMENT OF DAIRY PRODUCTS HEAVY METALS CONTENT IN SOME AREAS SURROUNDING BAIA MARE TOWN

The paper investigated Cu, Ni, Co, Zn and Cd content in milk and cream collected from: Băiţa (13 km from Baia Mare), Ferneziu (a neighborhood of the city) and Nadiş (60 km from Baia Mare). The results showed the presence of these heavy metals in the studied dairy product in different concentrations. Thus, Cu, Co and Zn acumulated mostly in milk, while Ni and Cd had the highest levels in cream. Also, Zn had the highest level of concentration, of 10,82 mg ·kg -1 , in the milk collected from Băiţa and Cd the lowest one, of 0,11 mg ·kg -1 , in the milk obtained from Nadiş.

Influence of Processing and Fermentation on Concentrations of Zn, Ca, Mg, and Phosphate in Goat Milk

The aim of this study was to determine the influence of the manufacturing and fermentation process on the mineral composition of different types of goat milk and fermented products. Zn, Ca, Mg, and P concentrations were determined in 47 samples of raw, commercial, and commercial fermented goat milk from Southern Spain. Significantly higher P and Mg levels and significantly lower Zn levels were found in the raw goat milk than in the processed samples. P and Zn levels did not differ among the commercial fermented goat milks, which use different species of fermenting bacteria. Commercial fermented goat milk produced with species of probiotic starter bacteria increased Zn and Ca levels. This is one of first studies to report the influence of processing and fermentation on levels of Zn, Ca, Mg, and P in goat milk. These data should be considered in the estimation of daily dietary intakes of these elements.

Investigation of macro, micro and toxic element concentrations of milk and fermented milks products by using an inductively coupled plasma optical emission spectrometer, to improve food safety in Turkey

In this study, the quantification of macro, micro and toxic elements in milk and its products was carried out using inductively coupled plasma optical emission spectrometry (ICP-OES) after using sample preparation procedures (wet digestion, dry digestion, and microwave digestion). Samples were collected from farms and markets in Edirne, Turkey. Ca, Mg, Na, K, Cu, Fe, Mn, Zn, Al, and Ba concentrations in the farm milk and its products ranged from 823 to 1499, 109–476, 218–1498, 905–1694, 0.094–0.26, 2.0–3.7, 0.014–0.105, 1.2–5.2, 0.192–0.35 and 0.075–0.191mgkg−1 respectively. The results in commercial milk and milk based products (minimum-maximum in mg·kg−1) were: Ca 791–1518, Mg 107–518, Na 221–1594, K 901–1692, Cu 0.068–0.23, Fe 2.2–4, Mn 0.019–0.087, Zn 2–5, Al 0.124–0.40 and 0.080–0.197. Macro, micro and toxic element contents of the commercial milk and its products in this study generally were higher than that of the natural samples. However, a tolerable daily diet of these elements by the Trakya region is well below the Turkish Food Codex (TFC) levels of macro, micro and toxic elements.

Zinc, lead, and cadmium levels in serum and milk of lactating women in Ibadan, Nigeria.

Zinc (Zn) is known to interact with lead (Pb) and cadmium (Cd) reversing their toxicity and reducing their concentrations. However, lactating women are at high risk of developing Zn deficiency, which may result in Pb and Cd intoxication or increased exposure of breast-fed infants to Pb and Cd from breast milk. The aim of this study was to determine Zn, Pb, and Cd concentrations and examine their relationship in serum and breast milk of lactating women in Ibadan, Nigeria. Ninety-two lactating women were recruited into this study. Anthropometric measurements were assessed by standard methods while serum and breast milk concentrations of Zn, Pb, and Cd were assessed by atomic absorption spectrophotometry. Data analyzed statistically by Student's t test, Pearson's correlation coefficient, and a multiple regression model were significant at p < 0.05. Zn deficiency was observed in 12 (17.1%) of lactating women. Breast milk levels of Zn, Pb, and Cd were significantly higher than their levels in serum, whereas the ratios Zn:Pb and Zn:Cd in milk were significantly less than serum ratios. Significant negative correlation was observed between milk Pb and serum Zn:Pb while milk Cd correlated positively with milk Zn. Significant positive correlations were observed between serum Zn and serum Zn:Pb, serum Zn and serum Zn:Cd, as well as serum Zn:Cd and serum Zn:Pb. Serum Cd and serum Zn were significantly negatively related. Significant negative correlations between serum Pb and serum Zn:Pb as well as milk Zn:Pb. Serum Cd and serum Zn:Pb as well as serum Zn:Cd correlated negatively. Milk Cd and Zn/Cd positively related with milk Pb while milk Zn was a negatively related with milk Pb in a multiple regression model ( R2 = 0.333; p = 0.023). Breast milk may be contaminated by toxic metals. However, Zn supplementation in deficient mothers may protect maternal and infant health.

Use of human milk in the assessment of toxic metal exposure and essential element status in breastfeeding women and their infants in coastal Croatia

Pregnant and lactating women and infants are vulnerable population groups for adverse effects of toxic metals due to their high nutritional needs and the resultant increased gastrointestinal absorption of both, essential and toxic elements. Although breastfeeding is recommended for infants worldwide, as human milk is the best source of nutrients and other required bioactive factors, it is also a pathway of maternal excretion of toxic substances including toxic metals and thus a source of infant exposure. The aim of this research was to assess health risks in breastfeeding women in the coastal area of the Republic of Croatia and their infants (N=107) due to maternal exposure to Cd and Pb via cigarette smoking, and Hg via seafood and dental amalgam fillings, and their interaction with essential elements. Biological markers of exposure were the concentrations of main toxic metals Pb, Cd and Hg in maternal blood and three types of breast milk throughout lactation stages. Biological markers of effects were the levels of essential elements Ca, Fe, Cu, Zn and Se in maternal serum and breast milk. With regard to cigarette smoking as a source of exposure to Cd and Pb, there were effects of smoking on Cd concentration in blood and correlations between the smoking index and Cd concentrations in maternal blood (Ͽ=0.593; P<0.001) and mature milk (Ͽ=0.271; P=0.011) and Pb concentration in transitional milk (Ͽ=0.280; P=0.042). Regarding fish, we found correlations between weekly consumption frequency and total Hg concentrations in maternal blood (Ͽ=0.292; P=0.003) and mature milk (Ͽ=0.303; P=0.003). The number of dental amalgam fillings correlated with total Hg concentrations in colostrum (Ͽ=0.489; P=0.005) and transitional milk (Ͽ=0.309; P=0.018). As for the essential element status, only Se levels in maternal serum decreased by 10% in persons who continued smoking during pregnancy compared to non-smokers. In conclusion, the levels of main toxic metals Cd, Pb and Hg and essential elements Ca, Fe, Cu, Zn and Se in maternal blood and three types of breast milk samples in the studied area of coastal Croatia showed no risk of disrupted essential element levels with regard of toxic metal exposure in both breastfeeding women and their infants.

Concentrations of macroelements and trace elements in milk of Jersey cows

The aim of the study was to determine concentration of macroelements (P, Ca, Mg, Na, K), and some microelements, including toxic heavy metals (Cr, Fe, Mn, Zn, Cu, Co, Pb, Cd and Hg) in milk of Jersey cows. Milk samples were collected from Jersey cows kept in tie-stall barn in Greater Poland Province. The feeding was based on total mixed ration mixture. The maximum permitted level of Pb concentration in raw milk (0.02 mg/kg wet weight)was significantly exceeded (0.063±0.035 mg/dm3). The content of Hg was very low (0.106±0.057 μg/dm3).Significant (P£0.05) Spearman coefficient correlations were observed between contents of some elements in milk. Especially interesting were positive correlations of heavy metals: Cd-Cr, Co-Mn, Cr-Zn, Mn-Zn. Additionally the content of Ca was positively correlated with numerous elements: Hg, Cr, Cu, Mn, Zn, Mg, and negatively correlated with the content of Fe.

Erratum to: Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction.

The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36% of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D(103)E and T(288)S) were identified with high frequency (9 and 16%, respectively) and expression of T(288)S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A(28)D, K(66)N, Q(71)H, D(103)E, A(105)P, Q(137)H, T(288)S and T(312)K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either 'loss-of-function' or 'gain-of-function', and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.

Milk protein composition and stability changes affected by iron in water sources

Water makes up more than 80% of the total weight of milk. However, the influence of water chemistry on the milk proteome has not been extensively studied. The objective was to evaluate interaction of water-sourced iron (low, medium, and high levels) on milk proteome and implications on milk oxidative state and mineral content. Protein composition, oxidative stability, and mineral composition of milk were investigated under conditions of iron ingestion through bovine drinking water (infused) as well as direct iron addition to commercial milk in 2 studies. Four ruminally cannulated cows each received aqueous infusions (based on water consumption of 100L) of 0, 2, 5, and 12.5mg/L Fe2+ as ferrous lactate, resulting in doses of 0, 200, 500 or 1,250mg of Fe/d, in a 4×4Latin square design for a 14-d period. For comparison, ferrous sulfate solution was directly added into commercial retail milk at the same concentrations: control (0mg of Fe/L), low (2mg of Fe/L), medium (5mg of Fe/L), and high (12.5mg of Fe/L). Two-dimensional electrophoresis coupled with matrix-assisted laser desorption/ionization–tandem time-of-flight (MALDI-TOF/TOF) high-resolution tandem mass spectrometry analysis was applied to characterize milk protein composition. Oxidative stability of milk was evaluated by the thiobarbituric acid reactive substances (TBARS) assay for malondialdehyde, and mineral content was measured by inductively coupled plasma mass spectrometry. For milk from both abomasal infusion of ferrous lactate and direct addition of ferrous sulfate, an iron concentration as low as 2mg of Fe/L was able to cause oxidative stress in dairy cattle and infused milk, respectively. Abomasal infusion affected both caseins and whey proteins in the milk, whereas direct addition mainly influenced caseins. Although abomasal iron infusion did not significantly affect oxidation state and mineral balance (except iron), it induced oxidized off-flavor and partial degradation of whey proteins. Direct iron addition to milk led to lipid oxidation during storage at 4°C. Oxidation level was positively associated with the concentration of added iron. Minerals (Mg, P, Na, K, Ca, Zn) in milk were not affected by the added iron in milk. This study indicated that a small amount of iron contamination in bovine drinking water at the farm or incidental iron addition from potable water sources causes oxidation, affects milk protein composition and stability, and affects final milk quality.

Women with a Common Genetic Variant in ZnT2 (T288S) Have Altered Breast Milk Composition: Implications for Suboptimal Lactation

Few studies have explored the role of nutrigenomics in lactation biology. Recent studies from our lab found that non‐synonymous genetic variation in the zinc (Zn) transporter ZnT2 (SLC30A2) is common in women and is associated with both low and elevated milk Zn concentrations. Of those variants, a threonine to serine substitution at amino acid 288 (T288S) was detected in 12% of women and milk from these women had abnormally low milk Zn and significantly elevated milk sodium levels. Because elevated milk sodium has been associated with breast dysfunction, in this study, we characterized the functional consequence of expressing the T288S variant on breast milk composition in women and in mammary epithelial cells (MECs) ectopically expressing this variant in vitro. We hypothesized that mothers with T288S variant would express biological factors in milk that reflect suboptimal lactation performance. We found that protein, lactose and fat concentrations in milk from women with T288S were similar to women expressing wild‐type ZnT2. However, milk from women expressing T288S had significantly higher levels of citrate, lactoferrin, MMP‐2 activity, 4‐HNE, mucin‐4 and endoplasmin, all of which increase in response to reactive oxygen species (ROS). Consistent with the milk analyses, MECs transfected to express T288S in vitro had significantly greater ROS levels and expression of oxidative stress markers, mucin‐4 and endoplasmin, compared to MECs expressing wild‐type ZnT2. To determine if this increase in oxidative stress is associated with mammary gland involution, we measured p‐STAT3, a marker of involution and found that STAT3 activation was significantly increased in T288S‐expressing MECs compared to MECs expressing wild‐type ZnT2. Collectively, our data suggest that women expressing the T288S variant in ZnT2 may have enhanced oxidative stress in the breast that may lead to precocious involution and suboptimal lactation. Importantly, this study suggests that nutrigenomics may have important implications for breast function and implicates factors in breast milk as useful bioreporters of breast (dys)function and lactation performance.Support or Funding InformationIntramural funds to SLK

ZnT4 (SLC30A4)-null (“lethal milk”) mice have defects in mammary gland secretion and hallmarks of precocious involution during lactation

During lactation, highly specialized secretory mammary epithelial cells (MECs) produce and secrete huge quantities of nutrients and nonnutritive factors into breast milk. The zinc (Zn) transporter ZnT4 (SLC30A4) transports Zn into the trans-Golgi apparatus for lactose synthesis, and across the apical cell membrane for efflux from MECs into milk. This is consistent with observations in "lethal milk" (lm/lm) mice, which have a truncation mutation in SLC30A4, and present with not only low milk Zn concentration, but also smaller mammary glands, decreased milk volume, and lactation failure by lactation day 2. However, the molecular underpinnings of these defects are not understood. Here, we used lactating C57BL/6J(lm/lm) (ZnT4-null) mice to explore the consequences of a ZnT4-null phenotype on mammary gland function during early lactation. Lactating C57BL/6J(lm/lm) mice had significantly fewer, smaller, and collapsed alveoli comprising swollen, lipid-filled MECs during early lactation. These defects were associated with decreased Akt expression and STAT5 activation, indicative of defects in MEC secretion. In addition, increased expression of ZnT2, TNF-α, and cleaved e-cadherin concomitant with increased activation of STAT3 implicated the loss of ZnT4 in precocious activation of involution. Collectively, our study indicates that the loss of ZnT4 has profound consequences on MEC secretion and may promote tissue remodeling in the mammary gland during early lactation.

Contents of Trace Metal Elements in Cow Milk Impacted by Different Feedstuffs

Feedstuff intake plays key role in impacting the yield and quality of milk. In this study, we discussed the contents of trace metal elements in cow milk impacted by different feedstuffs. We detected the contents of Pb, Cd, As, Cu, Mg, Ca, Fe and Zn in different feedstuffs and milk by atomic absorption spectrophotometry. The determinations of Pb, Cd and As contents were by graphite furnace AAS and Cu, Mg, Ca, Fe and Zn was by flame atomic absorption spectrometry. The results showed that Pb, Cd, As and Cu presented in feedstuffs, but Pb, Cd and As were lowly detected in milk samples, and Cu was not detected in milk samples. The content of Mg in concentrates was lower than that in forages. However, the content of Mg in milk from concentrate feed was higher than that in forage feed. This suggested that the utilization of Mg in concentrate feed was higher than that in forage feed. The contents of Ca and Zn were opposite to Mg, and the utilization of Ca and Zn in forage feed was higher than that in concentrate feed. There was no obviously change law of Fe in different feedstuffs and milk samples. The relationship between the contents of trace metal elements in milk to feedstuffs would provide a theoretical basis for dairy farming. It would be useful for improving the milk yield and milk quality of dairy production.

Exome Sequencing of SLC30A2 Identifies Novel Loss- and Gain-of-Function Variants Associated with Breast Cell Dysfunction.

The zinc (Zn) transporter ZnT2 (SLC30A2) is expressed in specialized secretory cells including breast, pancreas and prostate, and imports Zn into mitochondria and vesicles. Mutations in SLC30A2 substantially reduce milk Zn concentration ([Zn]) and cause severe Zn deficiency in exclusively breastfed infants. Recent studies show that ZnT2-null mice have low milk [Zn], in addition to profound defects in mammary gland function during lactation. Here, we used breast milk [Zn] to identify novel non-synonymous ZnT2 variants in a population of lactating women. We also asked whether specific variants induce disturbances in intracellular Zn management or cause cellular dysfunction in mammary epithelial cells. Healthy, breastfeeding women were stratified into quartiles by milk [Zn] and exonic sequencing of SLC30A2 was performed. We found that 36% of women tested carried non-synonymous ZnT2 variants, all of whom had milk Zn levels that were distinctly above or below those in women without variants. We identified 12 novel heterozygous variants. Two variants (D(103)E and T(288)S) were identified with high frequency (9 and 16%, respectively) and expression of T(288)S was associated with a known hallmark of breast dysfunction (elevated milk sodium/potassium ratio). Select variants (A(28)D, K(66)N, Q(71)H, D(103)E, A(105)P, Q(137)H, T(288)S and T(312)K) were characterized in vitro. Compared with wild-type ZnT2, these variants were inappropriately localized, and most resulted in either 'loss-of-function' or 'gain-of-function', and altered sub-cellular Zn pools, Zn secretion, and cell cycle check-points. Our study indicates that SLC30A2 variants are common in this population, dysregulate Zn management and can lead to breast cell dysfunction. This suggests that genetic variation in ZnT2 could be an important modifier of infant growth/development and reproductive health/disease. Importantly, milk [Zn] level may serve as a bio-reporter of breast function during lactation.

Voltammetric determination of Pb, Cd, Zn, Cu and Se in milk and dairy products collected from Iran: An emphasis on permissible limits and risk assessment of exposure to heavy metals

This study was carried out to determine the concentrations of some heavy metals in dairy products, collected from five industrial regions in Iran (n=250 samples) during winter and summer in 2013. The samples were analyzed using the differential pulse anodic and cathodic stripping voltammetry technique. The obtained ranges of mean Pb, Cd, Cu, Zn and Se were as follow: in raw milk 14.0, 1.11, 427, 571, 2.19μgkg−1, in pasteurized milk 9.59, 1.0, 378, 447, 1.78μgkg−1, in cheese 14.5, 1.25, 428, 586, 1.68μgkg−1, in yoghurt 7.54, 0.99, 399, 431, 1.23μgkg−1 and in doogh 7.2, 0.84, 320, 369, 0.99μgkg−1, respectively. In nearly all cases the concentrations of the metals were below the international permissible limits and do not pose a health concern for the consumption of milk and dairy products in Iran.

Zn status of sows and piglets as affected by diet and sow parity

The objective of the present study was to evaluate if changes to dietary P, Ca and phytase concentrations and sow parity number affect mineral transfer to piglets during lactation and productive and reproductive performance in sows. In experiment 1, sows (n=112) received the same gestation and lactation diets, and were grouped according to parity number. Colostrum and milk on d 21 of lactation were sampled from sows and analyzed for Zn, Fe and Cu. Hair from piglets was also collected at the 21st day of lactation and analyzed for Zn. In experiment 2, sows (41) were distributed into 3 groups based on parity and 4 dietary lactation treatments: dietary treatments were a lactation diet with recommended concentrations of Ca, P and Zn (Rec), a lactation with reduced concentrations of Ca, P and Zn (Low0), the Low diet supplemented with 250FTU of phytase/kg feed (Low250), and the Low diet supplemented with 500FTU of phytase/kg feed (Low500). Titanium dioxide (TiO2) was added as indigestible marker to all diets. Fecal samples were obtained between d 21 and 25 of lactation and analyzed for Ca, P, Zn, Fe, Cu and Ti. Blood and colostrum samples were obtained on day of farrowing, and blood and milk samples were collected on d 21, for Zn, Fe and Cu analysis. In experiment 1, no differences in trace minerals were observed between parity groups for colostrum, milk and hair except milk Cu concentrations were greater in older sows (6th–10th parity number) and milk Zn concentrations tended to be greater in older (6th–10th parity number) sows. In experiment 2, sows fed Rec had greater intake and excretion of Ca, P and Zn than the other three treatments. Sows supplemented with phytase (Low250 and Low500) had greater P digestibility than those without phytase (Rec and Low0). Zn, Fe and Cu concentrations in plasma and milk did not change with treatment. Parity did not alter any of the variables measured except plasma Cu levels, which were greater following farrowing in youngest sows. Large amounts of Zn are secreted in milk in relation to the body Zn stores during lactation. This research suggests the amount of Zn secreted by sows appears to be constant and independent of parity or phytase use in lactation diets low in P and Ca.