1,721,003 research outputs found
Substratum-attached material from dissociated sponge cells as a possible explanation of their non-random motion.
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Contribution to the study of egg development and derivation in Oscarella lobularis (Porifera, Demospongiae). '
No full textThe architecture of canal system of Petrosia ficiformis and Chondrosia reniformis studied by corrosion casts (Porifera, Demospongiae).
No full textFree Radical-Dependent Ca2+ Signaling: Role of Ca2+-Induced Ca2+ Release
No full textPreviously we have shown that Fe3+ /ascorbate-induced Ca2+ release from scallop sarcoplasmic reticulum (SR) is
due to Ca2+-channel gating by free radicals. This study is aimed at demonstrating that Ca2+-induced Ca2+ release
(CICR) plays a role in this kind of Ca2+ release. Scallop SR vesicles were incubated with fluo-3 and exposed to
Fe3+ /ascorbate. Fluorimetric recordings showed massive Ca2+ release, with maximum rate and 50% release occurring
at 30 min after exposure. Conversely, the use of the probe for reactive oxygen species dihydrorhodamine or
the assay of malondialdehyde allowed oxyradical production to be traced for , 5 min only. Hence, although Ca2+
release started just after exposure to Fe3+ /ascorbate, most release occurred after free radical exhaustion. Ruthenium
red addition after Fe3+ /ascorbate slowed down the Ca2+ release, whereas cyclic adenosine 5'-diphosphoribose
addition accelerated it, indicating that the free radical-induced Ca2+ release from SR vesicles triggers a mechanism
of CICR that dramatically increases the initial effect
Origin of male gametes from choanocytes in Spongia officinalis (Porifera, Demospongiae).
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Ultrastructural study of the mature egg of Tethya citrina Sarà and Melone (Porifera, Demospongiae).
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Antioxidant role of metallothioneins: a comparatie overview.
No full textMetallothioneins (MTs) are sulfhydryl-rich proteins binding essential and non-essential heavy metals. MTs display in vitro oxyradical scavenging capacity, suggesting that they may specifically neutralize hydroxyl radicals. Yet, this is probably an oversimplified view, as MTs represent a superfamily of widely differentiated metalloproteins. MT antioxidant properties mainly derive from sulfhydryl nucleophilicity, but also from metal complexation. Binding of transition metals displaying Fenton reactivity (Fe,Cu) can reduce oxidative stress, whereas their release exacerbates it. In vertebrates, MT gene promoters contain metal (MRE) and glucocorticoid response elements (GRE), Sp and AP sequences, but also antioxidant response elements (ARE). MT neosynthesis is induced by heavy metals, cytokines, hormones, but also by different oxidants and prooxidants. Accordingly, MT overexpression increases the resistance of tissues and cells to oxidative stress. As for invertebrates, data from the mussel show that MT can actually protect against oxidative stress, but is poorly inducible by oxidants. In yeast, there is a Cu(I)-MT that in contrast to mammalCu-MT exhibits antioxidant activity, possibly due to differences in metal binding domains. Finally, as the relevance of redox processes in cell signaling is becoming more and more evident, a search for MT effects on redox signaling could represent a turning point in the understanding of the functional role of these protein
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