Trace Metal Regulation Research Articles

Functional significance and physiological regulation of essential trace metals in fish.

Trace metals such as iron, copper, zinc and manganese play essential roles in various biological processes in fish, including development, energy metabolism and immune response. At embryonic stages, fish obtain essential metals primarily from the yolk, whereas in later life stages (i.e. juvenile and adult), the gastrointestine and the gill are the major sites for the acquisition of trace metals. On a molecular level, the absorption of metals is thought to occur at least in part via specific metal ion transporters, including the divalent metal transporter-1 (DMT1), copper transporter-1 (CTR1), and Zrt- and Irt-like proteins (ZIP). A variety of other proteins are also involved in maintaining cellular and systemic metal homeostasis. Interestingly, the expression and function of these metal transport- and metabolism-related proteins can be influenced by a range of trace metals and major ions. Increasing evidence also demonstrates an interplay between the gastrointestine and the gill for the regulation of trace metal absorption. Therefore, there is a complex network of regulatory and compensatory mechanisms involved in maintaining trace metal balance. Yet, an array of factors is known to influence metal metabolism in fish, such as hormonal status and environmental changes. In this Review, we summarize the physiological significance of iron, copper, zinc and manganese, and discuss the current state of knowledge on the mechanisms underlying transepithelial metal ion transport, metal-metal interactions, and cellular and systemic handling of these metals in fish. Finally, we identify knowledge gaps in the regulation of metal homeostasis and discuss potential future research directions.

Influence of dietary iron exposure on trace metal homeostasis and expression of metal transporters during development in zebrafish☆

The present study investigated the effects of dietary iron (Fe) exposure on physiological performance and homeostatic regulation of trace metals during development (5–28 days post-fertilization; dpf) in zebrafish (Danio rerio). The results demonstrated that whole body Fe content was increased in 14 dpf larvae fed a high Fe diet. Cumulative mortality was also significantly elevated during exposure to the high Fe diet. Using droplet digital PCR, we observed that high Fe-exposed larvae exhibited an increase in mRNA levels of the Fe-storage protein ferritin, which appeared to be associated with the elevated level of whole body Fe content. Further, the results indicated that dietary Fe exposure induced transient changes in the mRNA expression levels of various metal transporters, including the iron transporter dmt1, and the zinc transporters zip8 and zip14. The expression of the epithelial Ca2+ channels (i.e., ecac) was also found to increase by high dietary Fe. Overall, our findings suggest that larval fish during the early nutritional transition period are sensitive to the effects of dietary Fe.

A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production.

Cyanobacterial blooms are becoming more common in freshwater systems, causing ecological degradation and human health risks through exposure to cyanotoxins. The role of phosphorus and nitrogen in cyanobacterial bloom formation is well documented and these are regularly the focus of management plans. There is also strong evidence that trace metals are required for a wide range of cellular processes, however their importance as a limiting factor of cyanobacterial growth in ecological systems is unclear. Furthermore, some studies have suggested a direct link between cyanotoxin production and some trace metals. This review synthesises current knowledge on the following: (1) the biochemical role of trace metals (particularly iron, cobalt, copper, manganese, molybdenum and zinc), (2) the growth limitation of cyanobacteria by trace metals, (3) the trace metal regulation of the phytoplankton community structure and (4) the role of trace metals in cyanotoxin production. Iron dominated the literature and regularly influenced bloom formation, with 15 of 18 studies indicating limitation or colimitation of cyanobacterial growth. A range of other trace metals were found to have a demonstrated capacity to limit cyanobacterial growth, and these metals require further study. The effect of trace metals on cyanotoxin production is equivocal and highly variable. Better understanding the role of trace metals in cyanobacterial growth and bloom formation is an essential component of freshwater management and a direction for future research.

Redox and trace metal regulation of ion channels in the pain pathway.

Given the clinical significance of pain disorders and the relative ineffectiveness of current therapeutics, it is important to identify alternative means of modulating nociception. The most obvious pharmacological targets are the ion channels that facilitate nervous transmission from pain sensors in the periphery to the processing regions within the brain and spinal cord. In order to design effective pharmacological tools for this purpose, however, it is first necessary to understand how these channels are regulated. A growing area of research involves the investigation of the role that trace metals and endogenous redox agents play in modulating the activity of a diverse group of ion channels within the pain pathway. In the present review, the most recent literature concerning trace metal and redox regulation of T-type calcium channels, NMDA (N-methyl-D-aspartate) receptors, GABAA (γ-aminobutyric acid A) receptors and TRP (transient receptor potential) channels are described to gain a comprehensive understanding of the current state of the field as well as to provide a basis for future thought and experimentation.

Investigation of Nutrient Elements in <i>Cucurbita pepo</i> Using Atomic Absorption Spectrometry

There are a number of factors to keep our health in good condition. One of them is the role of the proper amount of nutrient metals which play the important role in many reactions in the body and it becomes increasingly evident that keeping a balance level of nutrient metals in every organ is very important for maintaining a healthy body, although metals comprise only a fraction of total body weight (mg). They play crucial role for many body functions in the metabolic regulations of the human body including transporting oxygen, normalizing the nervous system. The present investigation is focused to find out the different nutrient metals that exist in the vegetable Cucurbita pepo (squash) a source of natural nutrient metals abandance and to determine the relative concentration of each metal element. Investigation has been performed on the skin, the flesh, the seed, the leaves, the stems and the roots of squash to determine the relative levels of concentrations of various metals such as elements such as Al, Ca, Cd, Co,Cr, Fe,K, Mg, Mn, Na, Ni, Pb and Zn. The Atomic Absorption Spectrometry technique is used. The proper vegetable consumption can improve the mineral and trace metal regulation and reduce cardiovascular diseases and certain cancer risks.

Investigation of Nutrient Elements in <i>Cucurbita pepo</i> Using Atomic Absorption Spectrometry

There are a number of factors to keep our health in good condition. One of them is the role of the proper amount of nutrient metals which play the important role in many reactions in the body and it becomes increasingly evident that keeping a balance level of nutrient metals in every organ is very important for maintaining a healthy body, although metals comprise only a fraction of total body weight (mg). They play crucial role for many body functions in the metabolic regulations of the human body including transporting oxygen, normalizing the nervous system. The present investigation is focused to find out the different nutrient metals that exist in the vegetable Cucurbita pepo (squash) a source of natural nutrient metals abandance and to determine the relative concentration of each metal element. Investigation has been performed on the skin, the flesh, the seed, the leaves, the stems and the roots of squash to determine the relative levels of concentrations of various metals such as elements such as Al, Ca, Cd, Co,Cr, Fe,K, Mg, Mn, Na, Ni, Pb and Zn. The Atomic Absorption Spectrometry technique is used. The proper vegetable consumption can improve the mineral and trace metal regulation and reduce cardiovascular diseases and certain cancer risks.

Genetic analysis reveals polygenic influences on iron, copper, and zinc in mouse hippocampus with neurobiological implications

Fe, Cu, and Zn are of widespread neurobiological importance, but must be regulated closely as too much or too little of these metals can have adverse effects on brain function. Recent evidence from nutritional models notes that the hippocampus is particularly vulnerable to Fe and Zn deficiencies. We recently performed a quantitative trait loci (QTL) analysis as a preliminary step in identifying genes that contribute to natural variation in hippocampal Fe, Cu, and Zn content. We used ICP-MS to measure the concentrations of these metals in 120-day-old mice from 30 strains of the BXD/TY panel. The BXD/Ty recombinant inbred strain panel is well-suited for complex trait analysis, as all strains are genotyped with a dense marker set and have been phenotyped extensively for neurobehavioral traits and hippocampal gene expression. We observed a wide-range of hippocampal Fe, Cu, and Zn concentrations across the BXD strains. These concentrations were related to systemic Fe status, but not to Fe, Cu, and Zn elsewhere in the brain. The three metals also showed strong covariance, suggestive of overlap in their regulatory pathways. We identified two QTL, on chromosomes 14 and 9, most strongly associated with Cu but also suggestively associated with Fe (chr. 14) and Zn (chr. 9). We also performed genetic correlational analyses with existing data on these strains and revealed associations with cognitive, anxiety-related, and alcohol-related phenotypes. Covariance of these metals with gene expression is also discussed. This work shows that hippocampal Fe, Cu, and Zn are under polygenic influence and that trace metal regulation is associated with hippocampus-related behaviors. Future work will elucidate the genes underlying the two QTL identified, to aid in identifying homologous genetic variants in human populations, which may underlie altered trace metal homeostasis and related neurological disease.

Trace metal regulation of neuronal apoptosis: From genes to behavior

The genetically programmed form of neuronal death known as apoptosis plays a role in many neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and Huntington's disease. Apoptosis is also responsible for neuronal death after traumatic brain and spinal cord injury, stroke, and seizures. The cognitive and behavioral consequences of all of these disorders can be devastating. Unfortunately the mechanisms that regulate neuronal apoptosis are complex. However, it is this very complexity that provides us with a wide array of potential targets for the development of anti-apoptotic strategies. Thus, our lab is currently exploring the molecular and cellular mechanisms responsible for neuronal apoptosis, with a particular focus on the role of the metals copper, zinc, and iron. Each of these metals is essential for normal central nervous system (CNS) development and function. However, imbalances, either excess or deficiency, can result in neuronal apoptosis. In this review, we show the relationship between these metals in neurodegenerative disorders and CNS injury, and the mechanisms that govern neuronal survival and apoptosis.

Trace metals in the living and nonliving components of scleractinian corals

Trace metals in coral tissue and skeleton have been investigated in various ways since the early seventies. More recently it has been suggested that the symbiotic zooxanthellae may play an important role in the accumulation and regulation of trace metals. Furthermore gamete development and mucus production may influence the metal accumulation and loss in corals. Many studies have attempted to use the annual growth bands in coral skeletons to investigate historical pollution events. However the relationship between the metal concentrations in the surrounding environment and the incorporation of this into coral skeleton is not well understood. This paper explains a method for investigating metal loads in coral tissue, zooxanthellae and skeleton. Furthermore, it presents new information suggesting that zooxanthellae accumulate most metals (Al, Fe, As, Mn, Ni, Cu, Zn, Cd, Pb) in greater concentrations than the coral tissue. Coral skeletons had consistently lower metal concentration than the zooxanthellae, tissue and gametes. The loss of zooxanthellae during stress events may have a significant contribution to the total metal loads in corals. The use of corals as biomonitors should carefully factor in zooxanthellae densities and gamete development before conclusions are drawn.