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PubMed2026

Systematic mining and characterization of metal transporter families regulating zinc homeostasis provide insights into metal homeostasis in Camellia sinensis.

BACKGROUND AND AIMS: Zinc is essential for tea plant growth and quality formation, yet its homeostatic mechanisms remain poorly understood. This study identified metal transporter families regulating zinc homeostasis, analyzed their evolution, structure, and expression, and clarified zinc uptake, transport, detoxification networks, and their links to metabolism. METHODS: This study identified zinc homeostasis-related metal transporter families in the tea plant genome, characterized their structural features and expression profiles across tissues and developmental stages through integrative bioinformatics and transcriptomic analyses, and delineated the molecular mechanisms underlying zinc uptake, translocation, and detoxification by systematically integrating published evidence. RESULTS: This study identified 74 metal transporter genes from six families: 13 CsZIPs, 12 CsNRAMPs, 10 CsHMAs, 10 CsYSLs, 14 CsMTPs, and 15 CsCAXs in the 'Shuchazao2' genome, revealing closer affinity to woody species than to Arabidopsis. These proteins exhibit conserved domains, diverse subcellular localizations (cell membrane, vacuole, chloroplast, and Golgi apparatus), and tissue-specific expression with abundant stress/hormone-responsive cis-elements. At the plant-soil interface, tea plants mobilize rhizospheric zinc via proton and organic acid secretion; CsYSLs, CsNRAMPs, and CsZIPs mediate zinc uptake, aided by arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) that expand root absorption zones. Xylem CsHMAs and phloem CsYSLs coordinate root-to-shoot zinc translocation, and vacuolar transporters (CsMTPs, CsCAXs), cell wall immobilization, and antioxidant systems alleviate high-zinc stress injury. CONCLUSIONS: These findings collectively delineate an integrated zinc "acquisition-distribution-buffering" network in tea plants, offering a repertoire of candidate genes with potential utility in zinc biofortification breeding and improving acid soil adaptation. Further experimental validation, including tea transgenesis, zinc-stress qRT-PCR, and heterologous functional complementation, is essential to substantiate their biological roles.

Camellia sinensis↗

PubMed2026

Comparative efficacy and safety of bi-flanged metal stents versus lumen-apposing metal stents for endoscopic drainage of pancreatic fluid collections: a systematic review and meta-analysis.

INTRODUCTION: Pancreatic fluid collections (PFCs), particularly walled-off necrosis, are common complications of acute pancreatitis that often require endoscopic drainage. Bi-flanged metal stents (BFMS; NAGI; Taewoong Medical, Gyenoggi-do, Korea) and electrocautery-enhanced lumen-apposing metal stents (LAMS; AXIOS, Boston Scientific Corporation, Marlborough, Massachusetts, USA) are frequently used, but comparative data remain limited. This study aims to compare the efficacy and safety of BFMS and LAMS in the endoscopic drainage of PFCs. METHODS: This meta-analysis followed the Cochrane Handbook for Systematic Reviews of Interventions and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Comprehensive database searches were conducted through November 2024 to identify studies comparing BFMS and LAMS for endoscopic ultrasound-guided drainage of PFCs. Outcomes were pooled using a random-effects model with RevMan Web, and statistical significance was defined as a P value less than 0.05. RESULTS: Three studies ( n  = 627; 329 BFMS and 298 LAMS) met inclusion criteria. No significant differences were observed between BFMS and LAMS for technical success [odds ratio (OR): 1.16; 95% confidence interval (CI): 0.55-2.43] or clinical success (OR: 0.97; 95% CI: 0.51-1.87). Similarly, there were no differences in walled-off necrosis recurrence (OR: 2.01; 95% CI: 0.17-24.02), number of direct endoscopic necrosectomy sessions (OR: 0.52; 95% CI: 0.05-5.12), or mean number of endoscopic procedures (mean difference: 0.18, 95% CI: 2.08-2.45). Adverse events were also comparable between groups, including bleeding (OR: 0.64), infection (OR: 1.18), stent migration (OR: 1.83), and stent occlusion/dysfunction (OR: 1.71). CONCLUSION: BFMS and LAMS provide equivalent efficacy and safety in the endoscopic ultrasound-guided drainage of PFCs. Either stent type represents a viable therapeutic option. Further large-scale prospective studies are warranted to refine stent selection strategies.

Humans↗

PubMed1979

Fluoride inhibition of inorganic pyrophosphatase. IV. Evidence for metal participation in the active center and a four-site model of metal effect on catalysis.

Atomic spectroscopy of native yeast inorganic pyrophosphatase (pyrophosphate phosphohydrolase, EC 3.6.1.1) after gel filtration showed that it only binds activating Mg2% in an easily dissociable manner. Formation of a covalent intermediate between the enzyme and an entire substrate molecular in the presence of fluoride, however, dramatically strengthened the binding of two Mg2+ per subunit and eliminated at neutral pH the effect of added metals on protein fluorescence but not on the absorption spectrum, suggesting that different mental binding sites influence the two spectra. This conclusion was confirmed by spectra studied on native enzyme. A third, low-affinity site for Mg2+ was found on the enzyme pH greater than 8. A model of enzyme-substrate-metal interactions was proposed, according to which the fluorescence-controlling site belongs to the active center and substrate can only be bound to it as a 1 : 1 complex with metals.

Binding Sites↗

PubMed1975

Heavy metals in normal Japanese tissues. Amounts of 15 heavy metals in 30 subjects.

To obtain the usual values of arsenic, beryllium, bismuth, cadmium, chromium, cobalt, copper, mercury, methyl mercury, manganese, molybdenum, nickel, lead, antimony, vanadium, and zinc in the normal human body, the amounts of 15 metals were determined in 15 male and 15 female Japanese cadavers (average weight, 55 kg [121 lb]). The content of metals found ranged as follows: Zn, 1,800 mg; Cu, 65 mg; Cd, 35 mg; Pb, 25 mg; Mn, 8 mg; Ni, 6 mg; Cr, 4 mg; Hg, 3 mg; Sb, 0.7 mg; MeHg, 0.4 mg. Cadmium and mercury were higher in Japanese blood than in blood of other people. Cadmium and mercury were absorbed by the metabolic tissues; Cr, Ni, and Pb showed higher concentration in tissue exposed to the environment. Concentrations of Cd, Pb, and Hg tended to be higher in females, and Cr Cu, MeHg, and Mn concentrations tended to be higher in males.

Adolescent↗

PubMed1979

Toxic trace metals in food. I. A new voltammetric procedure for toxic trace metal control of wines.

A new highly sensitive and particularly reliable analytical procedure for the precise determination of the most relevant toxic trace metals cadmium, lead and copper in wine is presented. It consists of a simple and convenient sample pretreatment by UV irradiation (1,5 h, 500-W-Hg-lamp) to release the toxic trace metals bound by organic substances and subsequent voltammetry (DPASV) of cadmium and lead simultaneously at a mercury film electrode (MFE) formed in situ on a vitreous carbon carrier and of copper on a gold electrode. Particular emphasis has been placed on the efficient exclusion of interference due to contamination. Only special wines, with more than 10% of sugar, require substitution of UV irradiation by a wet digestion also described. The procedure may be easily expanded to include the determination of mercury and zinc.

Electrodes↗

PubMed1979

Toxic trace metals in food. II. A comparative study of the levels of toxic trace metals in wine by differential pulse anodic stripping voltammetry and electrothermal atomic absorption spectrometry.

A new high-performance analytical procedure for the determination of the toxic trace metals cadmium, lead and copper in wines by differential pulse anodic-stripping voltammetry (DPASV) subsequent to UV irradiation of the sample is compared with the hitherto more common application of electrothermal atomic absorption spectrometry (AAS). In this manner also mutually the accuracy attainable with both alternatives has been established. The particularly favourable potentialities of the new voltammetric approach for toxic metal control of wines are demonstrated by the investigation of a typical selection of 36 wines from recent vintages and common vine types of the German and some European wine cultivating regions.

Cadmium↗

PubMed1975

The nature of metal-ligand bonding in the primary hydration shell and in ionophores with alkali metal ions.

1. Trasport of alkali ions in model membranes mediated by ionophores is associated with at least two basic problems: (a) a conceivable physical model for the metal-ligand bonding in the primary hydration shell and (b) migration of ions from the primary hydration shell to ionophores to form ion complexes. 2. The nature of metal-ligand bonding both in the primary hydration shell and in the ionophores has been found to be around 80% ionic and 20% covalent in both cases by indepdnent investigation. Clearly the energetics being equivalent in both systems, ions will not migrate from the former to the latter. 3. A novel model is proposed in terms of hydrogen bonding in the primary hydration shell for Li+ and Na+ so that the migration of these ions to ionophores is easily envisaged. Hydrogen bonding contribures 18% and 5% of the energy to the total hydration shell energy of Li+ and Na+, respectively.

Acetamides↗

PubMed1976

Metal-polynucleotide interactions. A comparison of carcinogenic and non-carcinogenic metals in vitro.

The effects of divalent cations on mixing curves of synthetic polyribonucleotides in solution are described. Manganese and cadmium chlorides at 10(-3) M induce changes suggestive of base mispairing. MnCl2 induces mispairing in complexes formed between both poly(I) and poly(C,U) and poly(I) and poly(C,A) while CdCl2 affects base pairing between poly(I) and poly(C,U) only. By contrast, the chlorides of magnesium and zinc show no mispairing effects with either polymer pair. Manganese and cadmium are both reported carcinogens in animals while magnesium and zinc are not. The possibility that direct metal-nucleic acid interaction may be involved in metal carcinogenesis is discussed.

Binding Sites↗

PubMed1992

Immunodetection of recombinant proteins based on antibodies directed against a metal binding peptide engineered for purification by immobilized metal affinity chromatography.

Recently we reported (Evans, D.B., Tarpley W.G. and Sharma, S.K. (1991) Expression and characterization of chimeric rDNA proteins engineered for purification and cleavage. Protein Expr. Purif. 2, 205-213) a genetically engineered metal binding peptide (mbp) for the purification of recombinant proteins by immobilized metal affinity chromatography (IMAC). Therefore, we have been interested in developing mbp-based immunodetection methods for these engineered proteins. To this end, the following linker peptide containing the mbp (His-Asp-His-Asp-His) was designed, synthesized and conjugated to porcine thyroglobulin: Ac-Cys-Gly-Glu-Glu-His-Asp-His-Asp-His-Pro-Phe-His-Leu. Rabbits immunized with this conjugate developed antibodies that cross-react with peptides containing the mbp sequence. A number of chimeric recombinant proteins, expressed in E. coli, with and without the mbp portion (His-Asp-His-Asp-His) of the fusion peptide (His-Asp-His-Asp-His-Pro-Phe-His-Leu) were analyzed by ELISA and immunoblotting. Results from these studies show that the anti-mbp antibodies detect chimeric proteins containing the mbp, while chimeric proteins lacking this pentapeptide were negative in both immunodetection techniques. The usefulness of this approach has also been demonstrated in following IMAC purification and enzymatic cleavage of the mbp. These immunodetection techniques utilizing anti-mbp antibodies should be applicable to other proteins engineered to contain the mbp for IMAC purification.

Amino Acid Sequence↗

PubMed1975

Energy transfer between terbium (III) and cobalt (II) in thermolysin: a new class of metal--metal distance probes.

The visible fluorescence of terbium(III) when bound to a calcium binding site of thermolysin is greatly enhanced with an excitation maximum at 280 nm but substitution of cobalt(II) for zinc at the active site decreases the intensity by 89.5%. Treatment with N-bromosuccinimide quenches enzyme tryptophan and Tb(III) fluorescence to a similar extent and suggests the operation of tryptophan vector Tb(III) vector Co(II) energy relay system in the enzyme. Dipoledipole radiationless energy transfer between the Tb(III) donor and the Co(II) acceptor can account for this quenching. The inherent characteristics of the metal pair limits the value of the orientation factor, K2, of the Förster equation, thereby reducing uncertainties in distance measurements by energy transfer compared with other systems. A quantum yield of 0.51 yields a value of R0, the distance for 50% energy transfer, of 19.6 A, and a distance, R, between Tb(III) and Co(II) of 13.7 A, a value identical to that measured for the distance between the active site zinc atom and calcium atom number 1 by x-ray analysis in native thermolysin crystals. The limits of confidence of this measurement are discussed. Energy transfer between two different metal atom sites of a protein provides a new class of probes to measure intramolecular distances of biological macromolecules in solution.

Binding Sites↗

PubMed1977

Metal-free and metal-substituted cytochromes c. Use in characterization of the cytochrome c binding site.

The luminescent properties of metal-free, tin(IV) and zinc(II) cytochromes c have been used to characterize the interaction of cytochrome c with mitochondria and cytochrome oxidase. Diminution in the fluorescence yields of tin and zinc cytochrome c occur when these derivates bind to cytochrome oxidase or mitochondria. Based upon spectral overlap and quantum yield, the distance between the porphyrin rings of cytochrome a and cytochrome c is estimated according to Forster theory to be in the neighborhood of 3.5 nm. Measurements of the polarized emission of metal-free 'porphyrin' cytochrome c when bound to oriented layers of cytochrome c oxidase indicate that the porphyrin is bound obliquely to the plane of the oxidase layers with an angle of about 70 degrees C from heme plane to membrane plane. It is proposed that these data have significance for elucidation of electron transfer mechanisms.

Animals↗

PubMed1976

[Studies on high temperature oxidation of noble metal alloys for dental use. (III) On high temperature oxidation resistance of noble metal alloys by adding small amounts of alloying elements. (author's transl)].

The previous report pointed out the undesirable effects of high temperature oxidation on the casting. The influence of small separate additions of Zn, Mg, Si, Be and Al on the high temperature oxidation of the noble metal alloys was examined. These alloying elements were chosen because their oxide have a high electrical resistivity and they have much higher affinity for oxygen than Cu. The casting were oxidized at 700 degrees C for 1 hour in air. The results obtained were as follows: 1. The Cu oxides are not observed on the as-cast surface of noble metal alloys containing small amounts of Zn, Mg, Si, Be, and Al. The castings have gold- or silver-colored surface. 2. After heating of the unpolished and polished castings, the additions of Si, Be and Al are effective in preventing oxidation of Cu in the 18 carats gold alloys. Especially the golden surface is obtained by adding Be and Al. But there is no oxidation-resistance on the polished castings in the alloys containing Zn and Mg. 3. The zinc oxide film formed on the as-cast specimen is effective in preventing of oxidation Cu in 18 carats gold alloys. 4. It seems that the addition of Al is most available in dental application.

Aluminum↗

PubMed1976

Protein-metal ion interaction: volume effects produced by the interaction of proteins with metal ions.

The interaction of metal cations with single chain globular proteins produces volume increases, the magnitude of which is determined primarily by the ion and to a lesser extent by the protein. The cations are listed in ascending order of volume change: K(I) less than Mg(II) less than Sr(II) less than Ca(II) less than Co(II) less than Ni(II) less than Cd(II) less than Zn(II) less than Cu(II) less than Pb(II). This sequence held for all cation-protein systems investigated except for Cd(II) which produced a slightly larger volume effect than Zn(II) with lysozyme. The volume changes attributed to protein-cation interaction are positive and range from 8 ml/10(5) g of protein for the reaction on 0.05 M KNO3 with bovine plasma albumin to 2320 ml/10(5) g of protein produced by the 0.20 M Pb(NO3)2-myoglobin system. A similar classification scheme was not possible for the proteins. For example, volume increases of 45, 50, 80 and 95 ml/10(5) g of protein were produced when 0.05 M Mg(II) reacted with bovine serum albumin, ovalbumin, sperm whale myoglobin and lysozyme, respectively. However, when 0.2 M Pb(II) was the reactant the values were 1930, 846, 2320, and 1120 ml/10(5) g of protein. Volume effects produced by Cr(III), Al(III) and Fe(III) were determined, but the calculated results are considered dubious because the volume changes are a complicated function of protein-cation and protein-proton interaction.

Cations↗

PubMed1976

Directed metal determination in pre- and post-natal stages of development of the islets of Langerhans by combined histochemical metal demonstration with electron probe X-ray microanalysis.

On the examples shown above it was possible to demonstrate that electron-X-ray microanalysis does not only present an important additional method for studying histochemical heavy metal reactions but can also be expected to provide, in combination with these, essential findings for the illustration of basic biological processes.

Animals↗

PubMed1978

Theoretical and practical considerations on the problem of metal--metal interaction.

The interaction between two metals, which can be either synergistic or antagonistic, implies that the behavior of one is changed by the presence of the other. Possible mechanisms of these interactions, which include chemical association, competition for carriers, metabolic changes, induction of binding proteins, membrane alterations are discussed.

Animals↗

PubMed1975

Silica gel thin-layer chromatography of acidic phospholipids. II. Chromatographic behaviour of phosphatidylserine and phosphatidic acid applied with different cation composition on adsorbents either free of metal ions or containing a surplus of divalent metal ions.

Different salt forms of phosphatidylserine and phosphatidic acid (two acidic phospholipids) have been subjected to thin-layer chromatography on two commonly used silica adsorbents, one of which (silica gel HR) is practically free of metal ions and the other (silica gel G) contains 13% of calcium sulphate as binder. The chromatographic behaviour was studied in an acidic, a neutral and a basic solvent. Both adsorbents provided usable systems for phosphatidylserine with each of the three solvents, except for silica gel G with the neutral solvent, in which system tailing was prominent. The inclusion of calcium sulphate in the silica gel tended to impair chromatography of phosphatidylserine in acidic and neutral solvents, but improved its chromatography in the basic solvent. In all the systems, the migration was independent of the cation composition of the applied phosphatidylserine samples. For the chromatography of phosphatidic acid, only three of the systems tested were usable, and in those three, the chromatographic behaviour was independent of the cation composition of the samples. The calcium sulphate in an adsorbent increased tailing of phosphatidic acid in acidic and neutral solvents, as it did for phosphatidylserine, whereas with the basic solvent, calcium sulphate in the adsorbent caused phosphatidic acid to remain at the origin. Two one-dimensional thin-layer chromatographic systems previously recommended for the chromatography of acidic phospholipids were unsuitable for the chromatography of phosphatidic acid under the conditions used here. For both phosphatidylserine and phosphatidic acid chromatographed in acidic systems, the solvent must contain water in addition to acetic acid if excessive tailing is to be avoided.

Calcium↗

PubMed1977

Porosity in base metal partial denture casting alloys, related industrial alloys, and pure metals.

Two types of specimens were cast from a variety of pure metals and alloys. A unidirectional solidification system was used for the production of the first, whilst a deliberate feeding problem was incorporated in the production of the second. The specimens were subjected to radiographic and metallographic evaluation in conjunction with porosity determinations, in order to ascertain how the amount and pattern of porosity varied with alloy complexity and alloy composition.

Absorptiometry, Photon↗

PubMed1979

Phase changes in base metal alloys along metal-porcelain interfaces.

Five commercial, base metal alloys used with porcelain were investigated. After oxidizing heat treatments and the porcelain bake, phase changes occurred in some alloys near the porcelain interface. These changes were due to the depletion of the matrix in alloying elements as a result of the oxidizing treatments.

Acid Etching, Dental↗