BioMetals (v.31, #2)

TiO2 and its composites as promising biomaterials: a review by Naveen Kumar; Nar Singh Chauhan; Anuj Mittal; Shankar Sharma (147-159).
TiO2 is a well-known material and has remarkable physical, chemical and biocompatible properties which have made it a suitable material in the biological world. The development of new TiO2-based materials is strongly required to achieve desired properties and applications. A large number of TiO2 composites have been synthesized and applied in various fields. The present review reports the utility of TiO2 and its composites in biosensing, in Photodynamic Therapy, as an antimicrobial agent and as a nanodrug carrier. The aim of this review is to discuss the biological application of the TiO2 based materials and some recent advancement in TiO2 to enhance its application in the biological world.
Keywords: Biocompatibility; Composites; Biosensing; Antimicrobial; Nanodrug carrier

Proteomic and genomic responses of plants to nutritional stress by Rout George Kerry; Gyana Prakash Mahapatra; Sushmita Patra; Santi Lata Sahoo; Chinmay Pradhan; Bijaya Kumar Padhi; Jyoti Ranjan Rout (161-187).
Minerals or trace elements in small amount are essential nutrients for every plant, but when the internal concentration exceeds the threshold, these essential elements do create phytotoxicity. Plant responses to elemental stresses are very common due to different anthropogenic activities; however it is a complex phenomenon with individual characteristics for various species. To cope up with the situation, a plant produces a group of strategies both in proteomic and genomic level to overcome it. Controlling the metal stress is known to activate a multigene response resulting in the changes in various proteins, which directly affects almost all biological processes in a living cell. Therefore, proteomic and genomic approaches can be useful for elucidating the molecular responses under metal stress. For this, it is tried to provide the latest knowledge and techniques used in proteomic and genomic study during nutritional stress and is represented here in review form.
Keywords: Genomics; Molecular responses; Multigene; Nutritional stress; Phytotoxicity; Proteomics

First generation silver(I) phosphines have garnered much interest due to their vast structural diversity and promising anticancer activity. Increasing incidences of cancer, side-effects to chemotherapeutic agents and redevelopment of tumors due to resistance prompts the exploration of alternative compounds showing anticancer activity. This study revealed the effective induction of cell death by a silver(I) thiocyanate 4-methoxyphenyl phosphine complex in a malignant esophageal cell line. Apoptotic cell death was confirmed in treated cells. Moreover, mitochondrial targeting via the intrinsic cell death pathway was evident due to low levels of ATP, altered ROS activity, mitochondrial membrane depolarization, cytochrome c release and caspase-9 cleavage. The complex displayed low cytotoxicity towards two human non-malignant, skin and kidney, cell lines. The findings reported herein give further insight into the selective targeting of silver(I) phosphines and support our belief that this complex shows great promise as an effective chemotherapeutic drug.
Keywords: Cancer; Anticancer drugs; Apoptosis; Mitochondria; Silver(I) phosphine

Decreased aluminium tolerance in the growth of Saccharomyces cerevisiae with SSO2 gene disruption by Toshiyoshi Yamamoto; Daiki Yamamoto; Keiji Rokugawa; Ko Yoshimura; Yuki Imura; Etsuro Yoshimura; Michio Suzuki (203-215).
Aluminium ions inhibit growth of the budding yeast Saccharomyces cerevisiae. Disruption of the SSO2 gene increased the susceptibility to aluminium. Sso2p belongs to the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) family. SSO2 has one paralogue, SSO1, which encodes Sso1p. The SNARE complex containing Sso1/2p plays a role in the recognition of plasma membrane targeted vesicle transport. The susceptibility to aluminium stress was not increased in the Δsso1 strain. The phenotype of aluminium ion influx between the wild-type and Δsso2 strains was not different, suggesting that Sso2p was involved in the elimination of cellular aluminium. However, the cellular lipid constitution of Δsso2 was richer in unsaturated fatty acids than the wild type, indicating that Sso2p is associated with lipid homeostasis of the plasma membrane. Aluminium treatment increased the production of reactive oxygen species (ROS) during proliferation. ROS production was increased in the Δsso2 strain after 3 h of aluminium treatment compared with the wild type. These results suggested that Sso2p plays a role in maintaining the lipid composition of the plasma membrane and the increase in unsaturated fatty acids amplified the production of ROS in the acute phase of aluminium stress. ROS derived from aluminium stress inhibited growth and resulted in the susceptibility of the Δsso2 strain.
Keywords: Aluminium tolerance; ROS; SNARE; Saccharomyces cerevisiae

Effect of zinc intake on hepatic autophagy during acute alcohol intoxication by Juan P. Liuzzi; Vijaya Narayanan; Huong Doan; Changwon Yoo (217-232).
Autophagy is a conserved mechanism that plays a housekeeping role by eliminating protein aggregates and damaged organelles. Recent studies have demonstrated that acute ethanol intoxication induces hepatic autophagy in mice. The effect of dietary zinc intake on hepatic autophagic flux during ethanol intoxication has not been evaluated using animal models. Herein, we investigated whether zinc deficiency and excess can affect autophagic flux in the liver in mice and in human hepatoma cells acutely exposed to ethanol. A mouse model of binge ethanol feeding was utilized to analyze the effect of low, adequate, and high zinc intake on hepatic autophagic flux during ethanol intoxication. Autophagic flux was inferred by analyzing LC3II/LC3I ratio, protein levels of p62/SQSTM1, Beclin1 and Atg7, and phosphorylation of 4EBP1. In addition, the degradation of the fusion protein LC3-GFP and the formation of autophagosomes and autolysosomes were evaluated in cells. Ethanol treatment stimulated autophagy in mice and cells. High zinc intake resulted in enhanced autophagy in mice exposed to ethanol. Conversely, zinc deficiency was consistently associated with impaired ethanol-induced autophagy in mice and cells. Zinc-deficient mice exhibited a high degree of ethanol-driven steatosis. Furthermore, zinc depletion increased apoptosis in cells exposed to ethanol. The results of this study suggest that adequate zinc intake is necessary for proper stimulation of autophagy by ethanol. Poor zinc status is commonly found among alcoholics and could likely contribute to faulty autophagy.
Keywords: Autophagy; Zinc; Ethanol; Liver; Zinc intake; Mice

The cytotoxicity effects of a novel Cu complex on MCF-7 human breast cancerous cells by Fatemeh Mohammadizadeh; Soudeh Khanamani Falahati-pour; Azadeh Rezaei; Maryam Mohamadi; Mohammad Reza Hajizadeh; Mohammad Reza Mirzaei; Alireza Khoshdel; Mohammad Ali Fahmidehkar; Mehdi Mahmoodi (233-242).
A variety of biological activities, such as anti-microbial and anti-tumor properties was reported for 1,10-phenanthroline and its copper complexes. In this study, the anti-proliferative activity of a novel  [Cu(L)(phen)] complex was investigated on MCF-7 breast cancer cells using MTT assay. Since chemotherapy is lake of ability to distinguish between normal cells from cancerous cells, therefore we also investigated the effect of  [Cu(L)(phen)] complex on normal L929 cells. The results showed that following 24 and 48 h exposure of cells with  [Cu(L)(phen)] complex, the IC50 values for MCF-7 were significantly lower than that recorded for L929 and normal cells were less sensitive than cancerous cells to the complex. Additionally, the  [Cu(L)(phen)] complex displayed a time- and concentration-dependent cytotoxic response, with MCF-7 and L929 cells. Also flow cytometry findings suggest that  [Cu(L)(phen)] complex is capable of decreasing cancer cell viability through apoptosis and did not efficiently activate the necrosis process.
Keywords: Apoptosis; Breast cancer; [Cu(L)(phen)] complex; Cytotoxicity; MCF-7 cell line

The metabolic effects of mercury during the biological cycle of vines (Vitis vinifera) by Adrián Spisso; Ernesto Verni; Keaton Nahan; Luis Martinez; Julio Landero; Pablo Pacheco (243-254).
Mercury (Hg) is a major environmental pollutant that can be disposed to the environment by human activities, reaching crops like vineyards during irrigation with contaminated waters. A 2-year study was performed to monitor Hg variations during reproductive and vegetative stages of vines after Hg supplementation. Variations were focused on total Hg concentration, the molecular weight of Hg fractions and Hg-proteins associations in roots, stems and leaves. Total Hg concentrations increased during reproductive stages and decreased during vegetative stages. Variations in length of these stages were observed, according to an extension of the vegetative period. Six months post Hg administration, in roots, stems and leaves, initial Hg proteic fractions of 200 kDa were catabolized to 66 kDa fractions according to a transition from reproductive to vegetative stages. However, 24 months after Hg supplementation, the 66 kDa Hg proteic fraction was continuously determined in a prolonged senescence. Accordingly, the identified proteins associated to Hg show catabolic functions such as endopeptidases, hydrolases, glucosidases and nucleosidases. Stress associated proteins, like peroxidase and chitinase were also found associated to Hg. During the reproductive periods of vines, Hg was associated to membrane proteins, such as ATPases and lipid transfer proteins, especially in roots where Hg is absorbed.
Keywords: Mercury; Proteins; Vines; Biological cycle

A search of R. atropurpurea transcriptome for sequences encoding the transporters of the Zrt-, Irt-like Protein (ZIP) family, which are in eukaryotes integral to Zn supply into cytoplasm, allowed the identification of RaZIP1 cDNA with a predicted product belonging to ZIP I subfamily; it was subjected to functional studies in mutant Saccharomyces cerevisiae strains. The expression of RaZIP1, but not RaZIP1 H208A or RaZIP1 H232A mutants lacking conserved-among-ZIPs transmembrane histidyls, complemented Zn uptake deficiency in zrt1Δzrt2Δ yeasts. RaZIP1 substantially increased cellular Zn uptake in this strain and added to Zn sensitivity in zrc1Δcot1Δ mutant. The Fe uptake deficiency in ftr1Δ strain was not rescued and Mn uptake was insufficient for toxicity in Mn-sensitive pmr1Δ yeasts. By contrast, RaZIP1 increased Cd sensitivity in yap1Δ strain and conferred Cd transport activity in yeasts, albeit with substantially lower efficiency compared to Zn transport. In metal uptake assays, the accumulation of Zn in zrt1Δzrt2Δ strain remained unaffected by Cd, Fe, and Mn present in 20-fold molar excess over Zn. Immunofluorescence microscopy detected functional hemagglutinin-tagged HA::RaZIP1 on the yeast cell protoplast periphery. Altogether, these data indicate that RaZIP1 is a high-affinity plasma membrane transporter specialized in Zn uptake, and improve the understanding of the cellular and molecular biology of Zn in R. atropurpurea that is known for its ability to accumulate remarkably high concentrations of Zn.
Keywords: Russula atropurpurea ; Metal uptake; Zinc transporter; ZIP family; Ectomycorrhizal fungi

Plasma metals as potential biomarkers in dementia: a case–control study in patients with sporadic Alzheimer’s disease by Jingshu Xu; Stephanie J. Church; Stefano Patassini; Paul Begley; Katherine A. B. Kellett; Emma R. L. C. Vardy; Richard D. Unwin; Nigel M. Hooper; Garth J. S. Cooper (267-276).
Sporadic Alzheimer’s disease (AD) is a neurodegenerative disorder that causes the most prevalent form of age-related dementia but its pathogenesis remains obscure. Altered regulation of metals, particularly pan-cerebral copper deficiency, and more regionally-localized perturbation of other metals, are prominent in AD brain although data on how these CNS perturbations are reflected in the peripheral bloodstream are inconsistent to date. To assess the potential use of metal dysregulation to generate biomarkers in AD, we performed a case–control study of seven essential metals and selenium, measured by inductively coupled plasma mass-spectrometry, in samples from AD and matched control cases. Metals were sodium, potassium, calcium, magnesium, iron, zinc, and copper. In the whole study-group and in female participants, plasma metal levels did not differ between cases and controls. In males by contrast, there was moderate evidence that zinc levels trended towards increase in AD [10.8 (10.2–11.5)] µmol/L, mean (± 95% CI; P = 0.021) compared with controls [10.2 (9.6–10.4)]. Thus alterations in plasma zinc levels differed between genders in AD. In correlational analysis, there was evidence for an increased number of ‘strong’ metal co-regulations in AD cases and differential co-modulations of metal pairs: copper-sodium (R control = − 0.03, R AD = 0.65; P = 0.009), and copper-calcium (R control = − 0.01, R AD = 0.65; P = 0.01) were significant in AD males, potentially consistent with reported evidence for dysregulation of copper in severely damaged brain regions in AD. In conclusion, our data suggest that the measurement of metals co-regulation in plasma may provide a useful representation of those metal perturbations taking place in the AD brain and therefore might be useful as plasma-based biomarkers.
Keywords: Alzheimer’s disease; Dementia; Neurodegeneration; Human plasma; Metal biomarker; Plasma-zinc levels

Bovine heart cytochrome c (bCyt c) is an extensively studied hemoprotein of only 104 residues. Due to the existence of isoforms generated by non-enzymatic deaminidation, crystallization of bCyt c is difficult and involves extensive purification and the use of microseeding or the presence of an electric field. Taking advantage of the capacity of cytochrome c (cyt c) to bind anions on its protein surface, the commercially available bCyt c was crystallized without extra purifications, using ammonium sulfate as precipitant and nitrate ions as additives. The structure of the ferric bCyt c in a new crystal form is described and compared with that previously solved at low ionic strength and with those of human and horse cyt c. The overall structure of bCyt c is conserved, while the side chains of several residues that play a role in the interactions of cyt c with its partners have different rotamers in the two structures. The effect of the presence of nitrate ions on the structure of the protein is then evaluated and compared with that observed in the case of ferrous and ferric horse heart cyt c.
Keywords: Hemoprotein crystallization; X-ray structure; Cytochrome c; Hot spots; Protein–protein recognition

Previous literature has highlighted the mechanisms of molecular toxicity induced by substances such as arsenic, cadmium, chromium, nickel, lead, barium and PCBs. The research was carried out on 20 volunteers, all the patients gave their consent to the research: the aim of the study was to evaluate the presence of metals and PCBs in these different matrices (blood and hair), correlating the biochemical data to pathological conditions present, and also to the area in which patients resided. Various quantitative determinations were carried out on samples of blood and hair for 14 heavy metals and on blood samples for 12 PCBs. For the 11 patients the results indicated that blood levels for half of the 14 displayed heavy metals measured considerably higher compared to the reference values, whilst the levels measured in hair evidenced some positive values significantly higher than the maximum reference. Of the 12 PCBs assayed in blood some showed higher positive values compared to the maximum tabular reference (although there is no clear reference quantified in the WHO-2005 report). In the 9 healthy patients heavy metals in the blood were within the expected target range, with those showing positive results (≤ 3 out of 14 heavy metals for each patient) having values only slightly higher than the reference maximum. The levels of 14 heavy metals measured in hair were below thresholds, and levels for the 12 PCBs measured in blood showed negativity or positivity with values close to the minimum benchmarks. The analyses carried out on biological matrices have uncovered important and significant differences between healthy and unhealthy subjects, both qualitative and quantitative differences with respect to heavy metals and PCBs. All patients with head and neck cancer enlisted for the study had heavy metal and PCB blood levels at least twice the maximum reference level. The levels of heavy metals in hair were at least double the maximum reference. In contrast, all healthy volunteers enrolled showed no significant levels for either metals or PCBs.
Keywords: Heavy metals; PCB; Oncogenesis; Head and neck tumors