The Accumulation and Distribution of Vanadium, Iron, and Manganese in Some Solitary Ascidians

Michibata, Hitoshi; Terada, Tomoyoshi; Anada, N.; Yamakawa, Kohji; Numakunai, Takaharu

doi:10.2307/1541632

Cited by 109 publications

(55 citation statements)

References 33 publications

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“…The color of body fluid is often related to respiratory pigments containing transition metals such as iron. Although H. roretzi contains rather high levels of various metals in hemocytes (20), the color appeared upon contact reaction was not due to heme compounds.Another candidate for the substrate is a DOPA(3,4-dihydroxyphenylalanine)-like substance that has recently been found in the hemocytes (3). This hypothesis is not contradictory to the fact that the color generated during contact reaction did not have any specific absorption.…”

Section: Discussionmentioning

confidence: 86%

Hemocytes Release Phenoloxidase upon Contact Reaction, an Allogeneic Interaction, in the Ascidian Halocynthia roretzi.

Akita

Hoshi

1995

Cell Struct. Funct.

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Keywords: allogeneic recognition/ascidian hemocyte/phenoloxidase/respiratory burst/exocytotic burst/superoxide anion ABSTRACT. Contact reaction is the morphological expression of allogeneic recognition by hemocytes in the ascidian, Halocynthia roretzi', namely they undergo an exocytotic burst upon contact with non-self (allogeneic) hemocytes in vitro. Wehave found that contact reaction is accompanied by a burst of cyanide-insensitive oxygen consumption that, unlike exocytotic events of mammalianphagocytes, is Ca2+-dependentand does not culminate in the production of superoxide anions or H2O2. Instead, the burst is due to the release of phenoloxidase from hemocytes as known for the self-defense systems in insects and crustaceans. The activity of phenoloxidase released from hemocytes corresponds well to the degree of contact reaction observed under the microscope. Therefore, it is possible to quantify the contact reaction simply by measuring the activity of phenoloxidase released from hemocytes into the medium.

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Section: Discussionmentioning

confidence: 86%

Hemocytes Release Phenoloxidase upon Contact Reaction, an Allogeneic Interaction, in the Ascidian Halocynthia roretzi.

Akita

Hoshi

1995

Cell Struct. Funct.

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“…Metal transport is a role played by HsTf for Fe(III) and proposed for Ti(IV) (51, 64, 65) and V(V) (52, 66, 67) and for other metal ions (68). This role is a likely possibility for nicaTf, considering that ascidians accumulate these ions at high concentration, many orders of magnitude higher than their environment, depending on the species (15)(16)(17)(18)(19)(20)69). The remarkable levels of these metal ions would almost certainly be toxic for humans.…”

mentioning

confidence: 99%

“…Thus far, a true monolobal transferrin has been found only in ascidians, marine invertebrate chordates that are on the evolutionary boundary between vertebrates and invertebrates (14). Ascidians often sequester high concentrations of metals (15)(16)(17)(18)(19)(20). They evolved 0.5-1 billion years ago, when the atmosphere was already oxidizing, and so Fe(III) handling mechanisms were already in place (19).…”

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confidence: 99%

On the evolutionary significance and metal-binding characteristics of a monolobal transferrin fromCiona intestinalis

Tinoco

Peterson

Lucchese

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Ascidians, especially those belonging to the class Ascidiacea in the suborder Phlebobranchia, accumulate extremely high levels of vanadium, a transition metal, from seawater (6,15). Vanadium ions are accumulated in the vacuole of a type of blood cell called vanadocytes, and the concentration of vanadium in these vacuoles reaches 350 mM, which is 10 7 times the concentration in seawater (13,24).…”

mentioning

confidence: 99%

Bioaccumulation of Copper Ions by Escherichia coli Expressing Vanabin Genes from the Vanadium-Rich Ascidian Ascidia sydneiensis samea

Ueki

Sakamoto

Yamaguchi

et al. 2003

Appl Environ Microbiol

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The genes encoding two vanadium-binding proteins, vanabin1 and vanabin2, from a vanadium-rich ascidian, Ascidia sydneiensis samea, were recently identified and cloned (T. Ueki, T. Adachi, S. Kawano, M. Aoshima, N. Yamaguchi, K. Kanamori, and H. Michibata, Biochim. Biophys. Acta 1626:43-50, 2003). The vanabins were found to bind vanadium(IV), and an excess of copper(II) ions inhibited the binding of vanadium(IV) to the vanabins in vitro. In this study, we constructed Escherichia coli strains that expressed vanabin1 or vanabin2 fused to maltose-binding protein (MBP) in the periplasmic space. We found that both strains accumulated about twenty times more copper(II) ions than the control BL21 strain, while no significant accumulation of vanadium was observed. The strains expressing either MBP-vanabin1 or MBP-vanabin2 absorbed approximately 70% of the copper ions in the medium to which 10 M copper (II) ions were initially added. The MBP-vanabin1 and MBP-vanabin2 protein expressed in the periplasm bound to copper ions at a copper: protein molar ratio of 8:1 and 5:1, respectively, but MBP did not bind to copper ions. These data showed that the metal-binding proteins vanabin1 and vanabin2 bound copper ions directly and enhanced the bioaccumulation of copper ions by E. coli.The decontamination of soil and water containing heavy metals from industrial activity is a burdensome problem. Bioremediation strategies, using microorganisms or plants with metal-binding ability, have been proposed as an attractive alternative, because these are effective at low metal concentrations and are less expensive and more efficient than physicochemical methods of removing heavy metals (4, 10). Furthermore, the recovery of metals from waste streams and the bioleaching of rare metals from natural seawater are important ways to recycle resources. Seawater contains valuable dissolved metals, including V, Cr, Mn, Co, Ni, Mo, and W. The total amounts of these metals in seawater are huge and are equivalent to estimated terrestrial deposits, although they occur at extremely low concentrations of 10 Ϫ7 to 10 Ϫ9 M. To recover these metals, studies have sought metal-binding peptides with the ability to bind heavy metals in various living organisms to improve the metal-binding abilities of microorganisms via heterologous expression. Many studies have focused on metallothioneins, which are small, cysteine-rich proteins that are widely distributed from prokaryotes to eukaryotes. When metallothioneins are expressed in the cytoplasm (20, 28) or periplasm (9, 20, 21) of Escherichia coli, the cells remove heavy metal ions, such as Cd 2ϩ , Hg 2ϩ , Pb 2ϩ , and Cu 2ϩ , from the culture media and accumulate them. Several studies have sought novel small peptides that enhance the bioaccumulation of specific metals (8,11,22).We have focused on the bioaccumulation of vanadium by ascidians (tunicates or sea squirts) (12,14,16,17). Ascidians, especially those belonging to the class Ascidiacea in the suborder Phlebobranchia, accumulate extremely high levels of vanadium...

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The Accumulation and Distribution of Vanadium, Iron, and Manganese in Some Solitary Ascidians

Cited by 109 publications

References 33 publications

Hemocytes Release Phenoloxidase upon Contact Reaction, an Allogeneic Interaction, in the Ascidian Halocynthia roretzi.

Hemocytes Release Phenoloxidase upon Contact Reaction, an Allogeneic Interaction, in the Ascidian Halocynthia roretzi.

On the evolutionary significance and metal-binding characteristics of a monolobal transferrin fromCiona intestinalis

Bioaccumulation of Copper Ions by Escherichia coli Expressing Vanabin Genes from the Vanadium-Rich Ascidian Ascidia sydneiensis samea

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