Intracellular acidity in the ascidian

Hawkins, Clifford J.; James, Gwenyth A.; Parry, David L.; Swinehart, James H.; Wood, Anne

doi:10.1016/0305-0491(83)90293-6

Cited by 14 publications

(16 citation statements)

References 14 publications

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“…9) suggests that each trivalent vanadium atom is linked to just one sulphate group. Complexation of the vanadophore sulphate may account for the findings of Hawkins et al (1983b) and Dingley et al (1982) that, contrary to earlier reports of a high intracellular acidity in phlebobranch vanadocytes (see Webb 1939, Biggs andSwinehart 1976). the concentration of free acid within intact vanadocytes is low, with a p H of 4 .…”

Section: Fig Ycontrasting

confidence: 72%

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Localisation of Vanadium, Sulphur and Bromine Within the Vanadocytes of Ascidia mentula Müller: A Quantitative Electron Probe X‐Ray Microanalytical Study

Lane

Wilkes

1988

Acta Zoologica

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Levels of vanadium, sulphur and bromine within the vanadopohores of Ascidia mentula vanadocytes have been determined by quantitative X‐ray microanalytical techniques. Values obtained for vanadophore vanadium in thin sections correspond to 2.5‐3.25% or 0.5‐0.65 molal aqueous solutions in vivo. Quantitation of sulphur in thin sections gives levels an order of magnitude lower than for vanadium, but it is likely that major losses of sulphur have occurred, since analysis of unfixed, air dried vanadocytes gives V/S atomic ratios close to unity. This 1: 1 ratio may have implications for the structure of the vanadium complex. Quantitation of bromine is less reliable, but levels of this halogen in vanadocytes are significant. The possibility that bromine, in the form of brominated metabolites, together with vanadium and acid, contribute to a multicomponent chemical defense role in ascidians is discussed.

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Section: Fig Ycontrasting

confidence: 72%

“…6 6 . 0 (Hawkins et al 1983b) or close to neutrality (Dingley et al 1982). The possible existence of only mildly acidic or near neutral intravacuolar conditions within vanadocytes is perhaps difficult to reconcile with the contention of earlier workers that a low p H is necessary to maintain the vanadium in the highly reduced V(II1) state.…”

Section: Fig Ymentioning

confidence: 86%

Localisation of Vanadium, Sulphur and Bromine Within the Vanadocytes of Ascidia mentula Müller: A Quantitative Electron Probe X‐Ray Microanalytical Study

Lane

Wilkes

1988

Acta Zoologica

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“…50 and references therein) fewer measurements have been made on iron-accumulating stolidobranch ascidians such as S. clava. Near neutral intracellular pH values for the stolidobranch ascidians Pyura stolonifera and Boltenia ovifera have been earlier reported (51,52). Our priorities for future research on S. clava hemocytes include measuring intracellular and intravacuolar pH and examining the trafficking of styelins (e.g.…”

Section: Fig 4 Sequence and Mass Spectrum Obtained From The Ms/ms Omentioning

confidence: 99%

Styelin D, an Extensively Modified Antimicrobial Peptide from Ascidian Hemocytes

Taylor¹,

Craig²,

Fischer³

et al. 2000

Journal of Biological Chemistry

105

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We isolated styelin D, a 32-residue, C-terminally amidated antimicrobial peptide, from the blood cells (hemocytes) of the solitary ascidian, Styela clava. Styelin D had remarkably extensive post-translational modifications, containing two novel amino acids, dihydroxyarginine and dihydroxylysine, and two distinctly unusual ones, 6-bromotryptophan and 3,4-dihydroxyphenylalanine. In addition, the peptide exhibited microheterogeneity because of differential mono-and dihydroxylation of several lysine residues. Gram-negative and Gram-positive bacteria, and this activity was retained in 200 mM NaCl. The role of the extensive modifications may be to preserve activity at low pH and/or high salinity because, under these conditions, the native peptide was considerably more active against the Gram-positive bacterial strains than its unmodified synthetic analogue. The peptide was also hemolytic and quite cytotoxic to eukaryotic cells. These broad ranging activities, combined with its relative abundance in ascidian hemocytes, suggest that styelin D plays a significant role in the innate immune mechanisms of S. clava.As primitive chordates, ascidians are excellent subjects for research into the evolution of vertebrate innate immunity. Although ascidians lack the immunoglobins and T cell receptors found in higher vertebrates, their hemocytes can recognize and destroy foreign materials such as antigens or non-selftissues that penetrate their tunic or contact their internal tissues (1). In certain ascidian species, vacuolated cells (including the berry-shaped morula cells) contain hemagglutinin (2, 3) and proteases (4, 5). The morula cells of Halocynthia roretzi contain halocyamines (tetrapeptides containing L-3,4-dihydroxyphenylalanine (DOPA) 1 and a 6-bromoindole) that are active against Gram-positive bacteria, fungi, marine bacteria, and some fish RNA viruses (6, 7). Phenoloxidase, perhaps acting in concert with DOPA-derived metabolites and proteins (8 -10), may also be a critical player in cellular defenses. Two families of antimicrobial polypeptides, clavanins and styelins, were identified from hemocytes of the stolidobranch ascidian, Styela clava. The former are histidine-rich, ␣-helical polypeptides with 23 amino acid residues and C-terminal amidation (11). The latter are phenylalanine-rich peptides with 32 amino acid residues (12). Whereas styelins demonstrated a broad pH optimum in killing bacteria, the clavanins showed optimal antibacterial activity at pH 5.5. The initial 20 amino acid residues of styelins A and B were sequenced and indicated an unusual structure consisting of several unidentified amino acid residues and hydroxylysine residues that are common only in collagen-like polypeptides. Although they were not specifically identified, the absorbancy of styelins at 280 nm suggested that methylated or otherwise modified tyrosine residues were present.Amino acid sequences corresponding to both the clavanins and styelins were identified using partial sequences and a cDNA library prepared from hemopoietic pharyngeal t...

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“…This implies that the low concentration of sulphate in plasmas (in respect to the concentration of sulphate in seawater), is not the result of the accumulation into cytoplasmic blood cell solutions. Considerable controversy still exists on the intracellular pH and concentration of sulphate in the intact blood cells of tunicates (Dingley elal.. 1982;Hawkins?/ al, 1983a;Frank etal.. 1986).…”

Section: Discussionmentioning

confidence: 99%

Inorganic Aspects of the Blood Chemistry of Ascidians. Ionic Composition, and Ti, V, and Fe in the Blood Plasma ofPyura chilensisandAscidia dispar

Román

Molina

Rivera

1988

The Biological Bulletin

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Intracellular acidity in the ascidian

Cited by 14 publications

References 14 publications

Localisation of Vanadium, Sulphur and Bromine Within the Vanadocytes of Ascidia mentula Müller: A Quantitative Electron Probe X‐Ray Microanalytical Study

Localisation of Vanadium, Sulphur and Bromine Within the Vanadocytes of Ascidia mentula Müller: A Quantitative Electron Probe X‐Ray Microanalytical Study

Styelin D, an Extensively Modified Antimicrobial Peptide from Ascidian Hemocytes

Inorganic Aspects of the Blood Chemistry of Ascidians. Ionic Composition, and Ti, V, and Fe in the Blood Plasma ofPyura chilensisandAscidia dispar

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