3H-<scp>l</scp>-histidine and 65Zn2+ are cotransported by a dipeptide transport system in intestine of lobster<i>Homarus americanus</i>

Conrad, Erik M.; Ahearn, Gregory A.

doi:10.1242/jeb.01401

Cited by 20 publications

(25 citation statements)

References 44 publications

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“…Supplementation with histidine has been shown to affect zinc uptake in a variety of physiological assays, including absorption by intestinal preparations from fish, crustaceans and mammals and zinc uptake by cells such as erythrocytes [54], [55], [56], [57], [58], [59]. These studies indicate that histidine may increase zinc solubility and/or availability for transporters, or that zinc and histidine may be cotransported across membranes.…”

Section: Discussionmentioning

confidence: 99%

Histidine Protects Against Zinc and Nickel Toxicity in Caenorhabditis elegans

et al. 2011

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Zinc is an essential trace element involved in a wide range of biological processes and human diseases. Zinc excess is deleterious, and animals require mechanisms to protect against zinc toxicity. To identify genes that modulate zinc tolerance, we performed a forward genetic screen for Caenorhabditis elegans mutants that were resistant to zinc toxicity. Here we demonstrate that mutations of the C. elegans histidine ammonia lyase (haly-1) gene promote zinc tolerance. C. elegans haly-1 encodes a protein that is homologous to vertebrate HAL, an enzyme that converts histidine to urocanic acid. haly-1 mutant animals displayed elevated levels of histidine, indicating that C. elegans HALY-1 protein is an enzyme involved in histidine catabolism. These results suggest the model that elevated histidine chelates zinc and thereby reduces zinc toxicity. Supporting this hypothesis, we demonstrated that dietary histidine promotes zinc tolerance. Nickel is another metal that binds histidine with high affinity. We demonstrated that haly-1 mutant animals are resistant to nickel toxicity and dietary histidine promotes nickel tolerance in wild-type animals. These studies identify a novel role for haly-1 and histidine in zinc metabolism and may be relevant for other animals.

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Section: Discussionmentioning

confidence: 99%

Histidine Protects Against Zinc and Nickel Toxicity in Caenorhabditis elegans

et al. 2011

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“…It is likely that some zinc is delivered into some cells by this process. For example, luminal zinc absorption by intestinal mucosa cells occurs via co-transport with histidine and is affected by luminal amino acids [24]. However, for systemic and intracellular zinc uptake and maintenance, such a co-transport process is not a likely major mechanism.…”

Section: Cellular Zinc Uptake Transport Processesmentioning

confidence: 99%

Evidence for operation of the direct zinc ligand exchange mechanism for trafficking, transport, and reactivity of zinc in mammalian cells

Costello

Fenselau

Franklin

2011

Journal of Inorganic Biochemistry

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In addition to its critical role in normal cell function, growth, and metabolism, zinc is implicated as a major factor in the development and progression of many pathological conditions and diseases. Despite this importance of zinc, many important factors, processes, and mechanisms of the physiology, biochemistry, and molecular biology of zinc remain unknown. Especially important is the unresolved issue regarding the mechanism and process of the trafficking, transport, and reactivity of zinc in cells; especially in mammalian cells. This presentation focuses on the concept that, due to the existence of a negligible pool of free Zn2+ ions in the mammalian cell environment, the trafficking, transport and reactivity of zinc occurs via a direct exchange of zinc from donor Zn-Ligands to acceptor ligands. This Zn exchange process occurs without the requirement for production of free Zn2+ ions. The direct evidence from mammalian cell studies is presented in support of the operation of the direct Zn-Ligand exchange mechanism. The paper also provides important information and conditions that should be considered and employed in the conduct of studies regarding the role and effects of zinc in biological/biomedical research; and in its clinical interpretation and application.

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“…The experimental perfusate (the experimental saline plus appropriate experimental treatments) was pumped through the intestine using a peristaltic pump (Instech Laboratories Inc., Plymouth Meeting, PA,) at a rate of 0.38 mL min -1 (Figure 7). This rate was previously shown to provide constant transmural transport in lobster intestine for more than 3 hr of incubation without added oxygen at 23°C (Conrad and Ahearn, 2005). (Ahearn and Maginniss, 1977).…”

Section: Animalsmentioning

confidence: 74%

Functional characterization of a putative disaccharide membrane transporter in crustacean intestine

2014

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Mechanisms of transepithelial absorption of dietary sucrose in the American lobster, Homarus americanus, were investigated to determine if disaccharide sugars can be transported across an animal gut intact. Intestines were mounted in a perfusion chamber to measure mucosal to serosal (MS) 14C‐sucrose transport. MS sucrose transport was a hyperbolic function of luminal sugar concentration, suggesting the presence of carrier‐mediated transport. Sodium‐dependent glucose transport inhibitor, phloridzin, partially decreased MS 14C‐sucrose transport, suggesting hydrolysis of 14C‐sucrose to glucose during transport. Phloretin, an inhibitor of Na+‐independent basolateral glucose transport, partially decreased MS 14C‐sucrose transport, suggesting that some 14C‐sucrose radioactivity may be transported to the blood as 14C‐glucose. Decreased MS 14C‐sucrose transport also occurred in the presence of the disaccharide trehalose. Thin‐layer chromatography (TLC) was used to identify the chemical nature of radioactively‐labeled sugars in the bath following transport and revealed that 14C‐sucrose was transported across the intestine largely as an intact molecule. Results suggest that disaccharide sugars may be transported intact across crustacean intestine and provide support for the occurrence of a disaccharide membrane transporter that has not previously been functionally characterized. Grant Funding Source: This project was supported by Agriculture and Food Research Initiative Competitive Grant no. 2010‐65

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3H-l-histidine and 65Zn2+ are cotransported by a dipeptide transport system in intestine of lobsterHomarus americanus

Cited by 20 publications

References 44 publications

Histidine Protects Against Zinc and Nickel Toxicity in Caenorhabditis elegans

Histidine Protects Against Zinc and Nickel Toxicity in Caenorhabditis elegans

Evidence for operation of the direct zinc ligand exchange mechanism for trafficking, transport, and reactivity of zinc in mammalian cells

Functional characterization of a putative disaccharide membrane transporter in crustacean intestine

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