Essential Trace Metals Research Articles

Can the level of copper in the hippocampus witness type-II diabetes versus Alzheimer's disease?

Copper is an essential trace metal ion involved in many key physiological processes and is the co-factor of the related enzymes, including the cytochrome c oxidase of the respiratory chain and the superoxide dismutases that takes part in the fight against oxidative stress. As for most of other trace elements, a proper copper homeostasis is crucial for a good health.1 Copper deficiency or excess represents pathologic conditions, as exemplified by the two genetic disorders, Menkes and Wilson diseases corresponding to a failure in copper absorption and distribution and to a failure in copper excretion, respectively.

Elemental and Proximate Compositions of Sesame Seeds and the Underlying Soil from Tsegede, Ethiopia.

The proximate compositions and elemental contents of sesame (Sesamum indicum) seeds and the underlying soil from different cultivation areas of Tsegede, Ethiopia, were investigated. The ash, protein, fiber, fat, and carbohydrate contents of the sesame seeds were determined following standard methods. Essential major (Ca and Mg) and trace metals (Fe, Zn, Cu, Mn, and Ni) in the sesame seeds and the underlying soil were determined by using flame atomic absorption spectroscopy. The sesame seeds contained high levels of fat (52.9 ± 1.5%), followed by protein (23.5 ± 0.9%). The seeds contained 525 ± 1 and 453 ± 38 mg/kg of Mg and Ca, respectively. Iron was the most abundant (37.8 ± 1.4 mg/kg) of the trace metals, followed by Zn (14.6 ± 2.2 mg/kg) and Cu (7.26 ± 0.84). Manganese and Ni were found only in minute amounts. The concentrations of the trace metals varied significantly across the different cultivation areas. Similar to the sesame seeds, iron was found in higher amounts (212.6 ± 2.6 mg/kg) in the underlying soil followed by Zn and Cu, which were both 28.8 mg/kg. The amounts of the trace elements, Fe, Cu, and Zn found in the soils were about 2 to 6 times higher than that found in the sesame seeds. Whereas, the concentrations of Mg and Ca present in the seeds were comparable with that determined in the soils. Correlation analysis indicated that the Fe and Cu contents of the sesame seeds are negatively influenced by the amounts of Mg and Ca present in the soil. Ca in the seeds was also negatively associated with the Mg levels in soil.

Urinary metal profiles in mother-offspring pairs and their association with early dysglycemia in the International Hyperglycemia and Adverse Pregnancy Outcome Follow Up Study (HAPO-FUS).

Variations in dietary intake and environmental exposure patterns of essential and non-essential trace metals influence many aspects of human health throughout the life span. To examine the relationship between urine profiles of essential and non-essential metals in mother-offspring pairs and their association with early dysglycemia. Herein, we report findings from an ancillary study to the international Hyperglycemia and Adverse Pregnancy Outcome Follow-Up Study (HAPO-FUS) that examined urinary essential and non-essential metal profiles from mothers and offspring ages 10-14 years (1012 mothers, 1013 offspring, 968 matched pairs) from 10 international sites. Our analysis demonstrated a diverse exposure pattern across participating sites. In multiple regression modelling, a positive association between markers of early dysglycemia and urinary zinc was found in both mothers and offspring after adjustment for common risk factors for diabetes. The analysis showed weaker, positive, and negative associations of the 2-h glucose value with urinary selenium and arsenic respectively. A positive association between 2-h glucose values and cadmium was found only in mothers in the fully adjusted model when participants with established diabetes were excluded. There was a high degree of concordance between mother and offspring urinary metal profiles. Mother-to-offspring urinary metal ratios were unique for each metal, providing insights into changes in their homeostasis across the lifespan. Urinary levels of essential and non-essential metals are closely correlated between mothers and their offspring in an international cohort. Urinary levels of zinc, selenium, arsenic, and cadmium showed varying degrees of association with early dysglycemia in a comparatively healthy cohort with a low rate of preexisting diabetes. Our data provides novel evidence for a strong correlation between mother and offspring urinary metal patterns with a unique mother-to-offspring ratio for each metal. The study also provides new evidence for a strong positive association between early dysglycemia and urinary zinc, both in mothers and offspring. Weaker positive associations with urinary selenium and cadmium and negative associations with arsenic were also found. The low rate of preexisting diabetes in this population provides the unique advantage of minimizing the confounding effect of preexisting, diabetes related renal changes that would alter the relationship between dysglycemia and renal metal excretion.

A three-step process of manganese acquisition and storage in the microalga Chlorella sorokiniana.

Metabolism of metals in microalgae and adaptation to metal excess are of significant environmental importance. We report a three-step mechanism that the green microalga Chlorella sorokiniana activates during the acquisition of and adaptation to manganese (Mn), which is both an essential trace metal and a pollutant of waters. In the early stage, Mn2+ was mainly bound to membrane phospholipids and phosphates in released mucilage. The outer cell wall was reorganized and lipids were accumulated, with a relative increase in lipid saturation. Intracellular redox settings were rapidly altered in the presence of Mn excess, with increased production of reactive oxygen species that resulted in lipid peroxidation and a decrease in the concentration of thiols. In the later stage, Mn2+ was chelated by polyphosphates and accumulated in the cells. The structure of the inner cell wall was modified and the redox milieu established a new balance. Polyphosphates serve as a transient Mn2+ storage ligand, as proposed previously. In the final stage, Mn was stored in multivalent Mn clusters that resemble the structure of the tetramanganese-calcium core of the oxygen-evolving complex. The present findings elucidate the bioinorganic chemistry and metabolism of Mn in microalgae, and may shed new light on water-splitting Mn clusters.

Alpha Lipoic Acid and Monoisoamyl-DMSA Combined Treatment Ameliorates Copper-Induced Neurobehavioral Deficits, Oxidative Stress, and Inflammation.

Copper (Cu), being an essential trace metal, plays several roles in biological processes, though exposure to Cu can be potentially toxic to the brain and a few other soft organs. In the present study, we investigated the effects of the combined administration of monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA), which is a new chelator, and alpha lipoic acid (ALA) and an antioxidant that is made naturally in the body and is also found in foods, against Cu-induced oxidative stress in rats. Rats were exposed to 20 mg/kg copper sulfate for 16 weeks once a day via the oral route. After 16 weeks of exposure, animals were divided into different sub-groups. Group I was divided into three subgroups: Group IA, control; Group IB, MiADMSA (75 mg/kg, oral); Group IC, ALA (75 mg/kg, oral), while Group II was divided into four subgroups: Group IIA, Cu pre-exposed; Group IIB, Cu+ MiADMSA; Group IIC, Cu+ ALA; Group IID, Cu+ ALA+ MiADMSA. Exposure to Cu led to significant neurobehavioral abnormalities; treatment with MiADMSA, and in particular MiADMSA + ALA, significantly ameliorated the neurobehavioral parameters and restored the memory deficits in rats. Oxidative stress variables (ROS, nitrite, TBARS, SOD, catalase) and inflammatory markers (TNF-α, and IL-1β), which were altered on Cu exposed rats, also responded favorably to ALA+ MiADMSA combined treatment. Thus, combined administration of MiADMSA and ALA might be a better treatment strategy than monotherapy with MiADMSA or ALA against Cu-induced neurotoxicity, particularly in reducing oxidative stress, neurobehavioral abnormalities, and inflammatory markers.

Differential modes of response to zinc chloride in the marine rotifers Brachionus plicatilis and Brachionus rotundiformis: Reproductive flexibility and stress-defensive activity

Zinc is an essential trace metal used extensively as a dietary supplement in the cultivation of aquatic organisms. This practice can expose species such as rotifers, which are essential live food sources for rearing larvae in aquaculture, to zinc overexposure, which can inhibit rotifer reproduction. However, rotifers with distinct ecological features may respond differently to exposure. This study investigates the tolerance, reproduction, behavior, and mitochondria-mediated stress and energy defenses of two species of rotifers, the temperate and relatively large Brachionus plicatilis and the tropical and smaller Brachionus rotundiformis, following acute exposure (0–72 mg/L) and seven days of chronic exposure (0–2 mg/L) to zinc chloride. The 24 h and 48 h median lethal concentrations of ZnCl2 for B. plicatilis and B. rotundiformis were 29.9 and 9.0 mg/L and 13.3 and 3.6 mg/L, respectively. Long-term exposure to ZnCl2 at concentrations of 0.0125–0.1 mg/L had no adverse effects on survival and fecundity in either species. However, higher levels of ZnCl2 induced different reproductive phenomena, particularly in sexual reproduction. In B. plicatilis, ZnCl2 at concentrations ≥1 mg/L accelerated maturation, shortened life expectancy, and inhibited mixis induction and resting egg production, while similar ZnCl2 treatments stimulated sexual reproduction in B. rotundiformis. Subsequently, we detected different metabolic patterns between the two rotifers: decreased lipid storage and sperm viability and overcompensated antioxidant reactions (e.g., copper‑zinc superoxide dismutase, catalase, and glutathione S-transferase) with significantly low reactive oxygen species (ROS) levels in B. plicatilis and enhanced copper‑zinc superoxide dismutase activity, ATP generation, and sperm viability in B. rotundiformis. In behavioral tests, ZnCl2 exposure enhanced the swimming speeds of males and females of both species, potentially affecting the energy available for reproduction and male-female encounter rates. In conclusion, chronic exposure to ZnCl2 (≥1 mg/L) caused reductive stress with low ROS levels in B. plicatilis, possibly inhibiting sexual reproduction. However, the positive effects on reproduction in tropical B. rotundiformis revealed a potential requirement for nutritional zinc. Species-specific reproductive sensitivity to zinc in temperate and tropical rotifers may reflect ecological adaptations.

Investigation of imbalances in essential/toxic metal levels in the blood of laryngeal cancer patients in comparison with controls.

Laryngeal carcinoma is one of the common types of head and neck cancer, with men being more likely than women to develop it. Diet, age, gender, smoking habits, and environmental factors play important roles in its development. The goal of this study was to ascertain if there were imbalances in essential and toxic trace metals owing to the initiation and progression of laryngeal cancer. Atomic absorption spectrometry was employed to quantify selected macroelements, and essential/toxic trace metals in blood of the cancerous patients and matching controls. Significantly higher concentrations of Pb, Cu, Fe, and Sr while substantially lower levels of Na, K, Ca, and Mg were observed in the cancer patients compared with the controls. Considerably disparate mutual relationships among the macroelements, and essential/toxic trace metals in the patients and controls were manifested by their correlation coefficients. Similarly, multivariate apportionment of the metal levels showed appreciably diverse associations and grouping in the patients and controls. The laryngeal cancer patients exhibited significant disparities in the metal levels among various sub-types (supraglottic, subglottic, transglottic, and glottic cancer) and stages (I, II, III, and IV) of the disease. Most of the metals revealed distinct differences based on the gender, habitat, age, eating preferences, and smoking habits in both donor groups. Overall, the study demonstrated significant imbalances among the macroelements, and essential/toxic trace metal levels in the blood of laryngeal cancer patients compared to the controls.

The Molecular Mechanisms of Defective Copper Metabolism in Diabetic Cardiomyopathy.

Copper is an essential trace metal element that significantly affects human physiology and pathology by regulating various important biological processes, including mitochondrial oxidative phosphorylation, connective tissue crosslinking, and antioxidant defense. Copper level has been proved to be closely related to the morbidity and mortality of cardiovascular diseases such as atherosclerosis, heart failure, and diabetic cardiomyopathy (DCM). Copper deficiency can induce cardiac hypertrophy and aggravate cardiomyopathy, while copper excess can mediate various types of cell death, such as autophagy, apoptosis, cuproptosis, pyroptosis, and cardiac hypertrophy and fibrosis. Both copper excess and copper deficiency lead to redox imbalance, activate inflammatory response, and aggravate diabetic cardiomyopathy. This defective copper metabolism suggests a specific metabolic pattern of copper in diabetes and a specific role in the pathogenesis and progression of DCM. This review is aimed at providing a timely summary of the effects of defective copper homeostasis on DCM and discussing potential underlying molecular mechanisms.

Impaired XK recycling for importing manganese underlies striatal vulnerability in Huntington's disease.

Mutant huntingtin, which causes Huntington's disease (HD), is ubiquitously expressed but induces preferential loss of striatal neurons by unclear mechanisms. Rab11 dysfunction mediates homeostatic disturbance of HD neurons. Here, we report that Rab11 dysfunction also underscores the striatal vulnerability in HD. We profiled the proteome of Rab11-positive endosomes of HD-vulnerable striatal cells to look for protein(s) linking Rab11 dysfunction to striatal vulnerability in HD and found XK, which triggers the selective death of striatal neurons in McLeod syndrome. XK was trafficked together with Rab11 and was diminished on the surface of immortalized HD striatal cells and striatal neurons in HD mouse brains. We found that XK participated in transporting manganese, an essential trace metal depleted in HD brains. Introducing dominantly active Rab11 into HD striatal cells improved XK dynamics and increased manganese accumulation in an XK-dependent manner. Our study suggests that impaired Rab11-based recycling of XK onto cell surfaces for importing manganese is a driver of striatal dysfunction in Huntington's disease.

ASSESSMENT OF HEAVY METAL CONCENTRATION IN SEDIMENT AND FISH (Oreochromis Niloticus AND Clarias Gariepinus) IN BONNY ESTUARY, NIGER DELTA, NIGERIA, AND THEIR HUMAN HEALTH IMPLICATIONS

This study was carried out to examine the concentration of heavy metals in fishes, sediments, and their associated human health implications from Bonny Estuary, Rivers, Nigeria. A total of twenty-four (24) fish specimens and four (4) sediment specimens were gathered and tested using standardized procedures for essential and non-essential trace metals. Simple descriptive and inferential statistics were used to analyze the data. In fish specimens, health risk indices for both carcinogenic as well as non-carcinogenic impacts of heavy metals were evaluated. The result of metal concentrations in Oreochromis niloticus and Clarias Gariepinus revealed Pb (10.88±3.24 to 37.12±0.42 mg/kg) and Cd (0.94±0.66 to 1.16±0.10 mg/kg) were greater than Food and Agriculture Organization allowable limits. The bioaccumulation variable revealed Pb as the greatest metal accumulator in both O.niloticus and C.gariepinus from sediment specimens. Pb had a hazard quotient (HQ) greater than 1.0, indicative of non-carcinogenic side effects. Cancer Danger (CR) values of Lead (Pb) in Oreochromis niloticus varied from 1.1 × 10−2 to 2.7 × 10−2, while those in Clarias gariepinus ranged from 1.5 × 10−2 to 3.3 × 10−2, showing that both breeds are carcinogenic. The CR values of Cd were as well discovered to surpass the standard parameters of 1.0 × 10−4. The results of this study reveal worrisome levels of Pb and Cd, which need an immediate awareness and quick response to mitigate their associated health risk.

Lack of a Zn/Co substitution ability in the polar diatom Chaetoceros neogracileRS19

AbstractFunctional substitution of the essential trace metals zinc (Zn) and cobalt (Co) within metalloenzymes has been well documented in marine diatoms and is known to be prevalent among varying genera and species. In contrast to the majority of species studied to date, we find that the polar diatom Chaetoceros neogracile RS19, originally isolated from the Ross Sea, Antarctica, has a Zn requirement that cannot be met by Co and thus does not demonstrate a Zn/Co substitution ability as assessed by growth rate. We investigated this diatom's inability to use Co to alleviate Zn‐limited growth rates at the transporter, sensor/chaperone, and metalloenzyme level using metal quota and proteomic analyses of cultures grown over a range of Zn and Co availability. Analysis of total cellular metal quotas revealed that, although incapable of substitution, this diatom still actively assimilated dissolved Co. We furthermore observed distinct trends in the abundance levels of putative α and θ‐CAs, ZIP transporters, Zn fingers, and a Zn chaperone in response to increasing media Zn2+. Overall, Co appears to be transported into the cell, but not efficiently utilized by Zn metalloenzymes.

Antimicrobial peptides: Defending the mucosal epithelial barrier.

The recent epidemic caused by aerosolized SARS-CoV-2 virus illustrates the importance and vulnerability of the mucosal epithelial barrier against infection. Antimicrobial proteins and peptides (AMPs) are key to the epithelial barrier, providing immunity against microbes. In primitive life forms, AMPs protect the integument and the gut against pathogenic microbes. AMPs have also evolved in humans and other mammals to enhance newer, complex innate and adaptive immunity to favor the persistence of commensals over pathogenic microbes. The canonical AMPs are helictical peptides that form lethal pores in microbial membranes. In higher life forms, this type of AMP is exemplified by the defensin family of AMPs. In epithelial tissues, defensins, and calprotectin (complex of S100A8 and S100A9) have evolved to work cooperatively. The mechanisms of action differ. Unlike defensins, calprotectin sequesters essential trace metals from microbes, which inhibits growth. This review focuses on defensins and calprotectin as AMPs that appear to work cooperatively to fortify the epithelial barrier against infection. The antimicrobial spectrum is broad with overlap between the two AMPs. In mice, experimental models highlight the contribution of both AMPs to candidiasis as a fungal infection and periodontitis resulting from bacterial dysbiosis. These AMPs appear to contribute to innate immunity in humans, protecting the commensal microflora and restricting the emergence of pathobionts and pathogens. A striking example in human innate immunity is that elevated serum calprotectin protects against neonatal sepsis. Calprotectin is also remarkable because of functional differences when localized in epithelial and neutrophil cytoplasm or released into the extracellular environment. In the cytoplasm, calprotectin appears to protect against invasive pathogens. Extracellularly, calprotectin can engage pathogen-recognition receptors to activate innate immune and proinflammatory mechanisms. In inflamed epithelial and other tissue spaces, calprotectin, DNA, and histones are released from degranulated neutrophils to form insoluble antimicrobial barriers termed neutrophil extracellular traps. Hence, calprotectin and other AMPs use several strategies to provide microbial control and stimulate innate immunity.

Role of Iron and Iron Overload in the Pathogenesis of Invasive Fungal Infections in Patients with Hematological Malignancies

Iron is an essential trace metal necessary for the reproduction and survival of fungal pathogens. The latter have developed various mechanisms to acquire iron from their mammalian hosts, with whom they participate in a continuous struggle for dominance over iron. Invasive fungal infections are an important problem in the treatment of patients with hematological malignancies, and they are associated with significant morbidity and mortality. The diagnosis of invasive clinical infections in these patients is complex, and the treatment, which must occur as early as possible, is difficult. There are several studies that have shown a possible link between iron overload and an increased susceptibility to infections. This link is also relevant for patients with hematological malignancies and for those treated with allogeneic hematopoietic stem cell transplantation. The role of iron and its metabolism in the virulence and pathogenesis of various invasive fungal infections is intriguing, and so far, there is some evidence linking invasive fungal infections to iron or iron overload. Clarifying the possible association of iron and iron overload with susceptibility to invasive fungal infections could be important for a better prevention and treatment of these infections in patients with hematological malignancies.

Examination of Trace Metals and Their Potential Transplacental Transfer in Pregnancy.

With the ever-growing concern for human health and wellbeing, the prenatal period of development requires special attention since fetuses can be exposed to various metals through the mother. Therefore, this study explored the status of selected toxic (Pb, Cd, Ni, As, Pt, Ce, Rb, Sr, U) and essential trace metals (Mn, Co, Cu, Zn, Se) in the umbilical cord (UC) sera, maternal sera, and placental tissue samples of 92 healthy women with normal pregnancies. A further aim focuses on the potential transplacental transfer of these trace metals. Based on the obtained levels of investigated elements in clinical samples, it was observed that all of the trace metals cross the placental barrier and reach the fetus. Furthermore, statistical analysis revealed significant differences in levels of toxic Ni, As, Cd, U, Sr, Rb, and essential Mn, Cu, and Zn between all three types of analyzed clinical samples. Correlation analysis highlighted As to be an element with levels that differed significantly between all tested samples. Principal component analysis (PCA) was used to enhance these findings. PCA demonstrated that Cd, Mn, Zn, Rb, Ce, U, and Sr were the most influential trace metals in distinguishing placenta from maternal and UC serum samples. As, Co, and Cu were responsible for the clustering of maternal serum samples, and PCA demonstrated that the Pt level in UC sera was responsible for the clustering of these samples. Overall, the findings of this study could contribute to a better understanding of transplacental transfer of these trace metals, and shed a light on overall levels of metal exposure in the population of healthy pregnant women and their fetuses.

Effect of Sublethal Copper Overload on Cholesterol De Novo Synthesis in Undifferentiated Neuronal Cells.

Although copper (Cu) is an essential trace metal for cells, it can induce harmful effects as it participates in the Fenton reaction. Involuntary exposure to Cu overload is much more common than expected and has been linked with neurodegeneration, particularly with Alzheimer’s disease (AD) evidenced by a positive correlation between free Cu in plasma and the severity of the disease. It has been suggested that Cu imbalance alters cholesterol (Chol) homeostasis and that high membrane Chol promotes the amyloidogenic processing of the amyloid precursor protein (APP) secreting the β-amyloid (Aβ) peptide. Despite the wide knowledge on the effects of Cu in mature brain metabolism, the consequence of its overload on immature neurons remains unknown. Therefore, we used an undifferentiated human neuroblastoma cell line (SH-SY5Y) to analyze the effect of sublethal concentrations of Cu on 1— de novo Chol synthesis and membrane distribution; 2—APP levels in cells and its distribution in membrane rafts; 3—the levels of Aβ in the culture medium. Our results demonstrated that Cu increases reactive oxygen species (ROS) and favors Chol de novo synthesis in both ROS-dependent and independent manners. Also, at least part of these effects was due to the activation of 3-hydroxy-3-methyl glutaryl CoA reductase (HMGCR). In addition, Cu increases the Chol/PL ratio in the cellular membranes, specifically Chol content in membrane rafts. We found no changes in total APP cell levels; however, its presence in membrane rafts increases with the consequent increase of Aβ in the culture medium. We conclude that Cu overload favors Chol de novo synthesis in both ROS-dependent and independent manners, being at least in part, responsible for the high Chol levels found in the cell membrane and membrane rafts. These may promote the redistribution of APP into the rafts, favoring the amyloidogenic processing of this protein and increasing the levels of Aβ.

Association between serum manganese levels and diabetes in Chinese adults with hypertension.

Manganese (Mn) is an essential trace metal element that is associated with diabetes; however, the results of previous studies are inconsistent. Furthermore, few studies have been conducted in a hypertensive population. The purpose of this study is to explore the relationship between manganese and diabetes in a population with hypertension. A cross‐sectional study was conducted, including 2575 hypertensive individuals from 14 provinces in China. Serum manganese concentrations were measured by the inductively coupled plasma mass spectrometry (ICP‐MS) method. And logistic regression models were used to analyze the association between serum manganese and the risk of diabetes. The prevalence of diabetes was 27.0% in this hypertensive population. In logistic regression models, the odds ratios (95% confidence interval) for diabetes in tertile subgroups were 1.40 (1.12, 1.76) and 1.32 (1.05, 1.65) for tertiles 1 and tertiles 3, respectively, compared to tertile 2 (reference). Additionally, an interaction between sex and manganese was observed. The odds ratios (95% confidence interval) for diabetes were 1.29 (0.95, 1.75) and 0.96 (0.70, 1.31) for tertiles 1 and tertiles 3 among males, and 1.44 (1.01, 2.04) and 1.81 (1.29, 2.55) for tertiles 1 and tertiles 3 among females, respectively, compared to tertile 2. In conclusion, a U‐shaped association between serum manganese and diabetes was observed in a Chinese population with hypertension, and the association was modified by sex.

Environmental effects on trace elements in the fingernails of centenarians and their offspring

Bio-monitoring is commonly used to investigate trace elements, and the human nail provides an ideal medium for such testing. Toxic and essential trace metals (Cd, Pb, Fe, and Se) in the fingernails of participants from the Hainan Province were investigated. Samples included 136 centenarians and 197 offspring (101 older adult children and 96 middle-aged grandchildren) who were also sampled for comparison. As a hotspot for longevity, participants in the Hainan Province were found to have high essential nutrients of Fe and Se, and lacked the toxic element Pb. A similar trend was found for trace elements in soil and rice in the Hainan Province. The trace elements preserved in nails revealed dietary and environmental influences that varied among different generations. For the grandchildren's generation, the environment played an important role in elements in their nails, and a significant correlation and linear relationships were found, especially for Fe and Se. As the participants increased in age (from the grandchildren to the centenarians), the correlation between various elements decreased. For centenarians, the influence of beneficial or harmful properties of the elements became more important than their environment. The results also pointed to the important role of trace elements in human health, especially Fe and Se as essential elements. This study can provide information on the factors that influence the existence of trace elements in the human body and demonstrate the advantage of using the human fingernail in bio-monitoring.

The role of zinc in the adaptive evolution of polar phytoplankton

Zinc is an essential trace metal for oceanic primary producers with the highest concentrations in polar oceans. However, its role in the biological functioning and adaptive evolution of polar phytoplankton remains enigmatic. Here, we have applied a combination of evolutionary genomics, quantitative proteomics, co-expression analyses and cellular physiology to suggest that model polar phytoplankton species have a higher demand for zinc because of elevated cellular levels of zinc-binding proteins. We propose that adaptive expansion of regulatory zinc-finger protein families, co-expanded and co-expressed zinc-binding proteins families involved in photosynthesis and growth in these microalgal species and their natural communities were identified to be responsible for the higher zinc demand. The expression of their encoding genes in eukaryotic phytoplankton metatranscriptomes from pole-to-pole was identified to correlate not only with dissolved zinc concentrations in the upper ocean but also with temperature, suggesting that environmental conditions of polar oceans are responsible for an increased demand of zinc. These results suggest that zinc plays an important role in supporting photosynthetic growth in eukaryotic polar phytoplankton and that this has been critical for algal colonization of low-temperature polar oceans.

Zinc Essentiality, Toxicity, and Its Bacterial Bioremediation: A Comprehensive Insight.

Zinc (Zn) is one of the most abundantly found heavy metals in the Earth’s crust and is reported to be an essential trace metal required for the growth of living beings, with it being a cofactor of major proteins, and mediating the regulation of several immunomodulatory functions. However, its essentiality also runs parallel to its toxicity, which is induced through various anthropogenic sources, constant exposure to polluted sites, and other natural phenomena. The bioavailability of Zn is attributable to various vegetables, beef, and dairy products, which are a good source of Zn for safe consumption by humans. However, conditions of Zn toxicity can also occur through the overdosage of Zn supplements, which is increasing at an alarming rate attributing to lack of awareness. Though Zn toxicity in humans is a treatable and non-life-threatening condition, several symptoms cause distress to human activities and lifestyle, including fever, breathing difficulty, nausea, chest pain, and cough. In the environment, Zn is generally found in soil and water bodies, where it is introduced through the action of weathering, and release of industrial effluents, respectively. Excessive levels of Zn in these sources can alter soil and aquatic microbial diversity, and can thus affect the bioavailability and absorption of other metals as well. Several Gram-positive and -negative species, such as Bacillus sp., Staphylococcus sp., Streptococcus sp., and Escherichia coli, Pseudomonas sp., Klebsiella sp., and Enterobacter sp., respectively, have been reported to be promising agents of Zn bioremediation. This review intends to present an overview of Zn and its properties, uses, bioavailability, toxicity, as well as the major mechanisms involved in its bioremediation from polluted soil and wastewaters.

Nutrient absorption in two Bison bison herds on the Fort Peck Indian Reservation

On the Fort Peck Reservation bison are separated into two pastures: a genetically pure bison herd (cultural herd) and a non‐genetically pure bison herd with cattle genes (business herd). Vital nutrients may be lacking in their diet, nutrients may not be absorbed or resident parasitic infections may block absorption. We are measuring the absorption of key nutrients such as short chain fatty acids (SCFA), glucose and essential trace metals. Ussing chamber studies ussing stomach tissue measure the absorption of some nutrients. Trace metals of copper and zinc are stored in the liver and measurements of those levels will determine deficiencies in the animals. It is also assumed that the same parasites that afflict cattle also populate bison. In addition, ruminants such as the bison rely on microbiota for proper digestion and absorption of SCFA and also require many of the same vital trace metals. Bison possess flaps of tissue that increase the surface area of the stomach compartments suggesting that nutrients are probably absorbed there but no studies have been performed to investigate this possibility. Plant materials were removed from the stomach compartments for future microbiota analysis. Fecal material has also been removed from the intestine and colon for microbiota comparison purposes comparing metal deficient animals with nourished animals. Tissue samples and fecal material from the two herds were removed and stored at 4˚ C for a week, and were analyzed for ova with Sheather’s Sugar Flotation Solution with a compound microscope. The remaining samples were stored for other experiments at 4˚ C. Results show higher infestation rates in the cultural herd than the business herd (0.4‐7.78 ova/gram for Strongyle, 0.4 ova/gram for Trichuris, 0.2‐0.67 ova/gram, and 0.6 ova/gram for Coccidia, versus the business herd which had no infestations). Next, we analyzed tract metal levels in liver samples between the two herds with mass spectroscopy. Essential trace metals were quantitatively shown to be deficient among the two herds. Copper levels were substantially lower at 7.8± 0.5 ppm for the cultural herd and 6.7±0.8) and for the business herd (normal levels are 87.5±16). Zinc values are also substantially lower at 30.57±0.5 for the cultural herd and 25± 2.6 for the business herd. (normal levels are 112.5± 12) Ussing Chamber experiments were performed on the reticulum (1st stomach) tissues of both cultural and business herds, with results in sodium‐glucose co‐transport in the first stomach of each of the twelve animals. Initial analysis of short circuit current (Isc) indicates glucose absorption (1.99±0.13 µAmp) and SCFA absorption (butyrate, 2.24±0.24 µAmp/ cm2) and however no differences seem to exist between the two herds. These studies suggest that there is a reduction of some nutrients such copper and zinc in bison that other nutrients such a glucose and SCFAs absorption does occur in the first stomach. Ova levels of the various herds is too low to have a significant effect on absorption of nutrients.