54 research outputs found
Fusicoccin Counteracts the Toxic Effect of Cadmium on the Growth of Maize Coleoptile Segments
The effects of cadmium (Cd; 0.1–1000 μM) and fusicoccin (FC) on growth, Cd2+ content, and membrane potential (Em) in maize coleoptile segments were studied. In addition, the Em changes and accumulation of Cd and calcium (Ca) in coleoptile segments treated with Cd2+ combined with 1 μM FC or 30 mM tetraethylammonium (TEA) chloride (K+-channel blocker) were also determined. In this study, the effects of Ca2+-channel blockers [lanthanum (La) and verapamil (Ver)] on growth and content of Cd2+ and Ca2+ in coleoptile segments were also investigated. It was found that Cd at high concentrations (100 and 1000 μM) significantly inhibited endogenous growth of coleoptile segments and simultaneously measured proton extrusion. FC combined with Cd2+ counteracted the toxic effect of Cd2+ on endogenous growth and significantly decreased Cd2+ content (not the case for Cd2+ at the highest concentration) in coleoptile segments. Addition of Cd to the control medium caused depolarization of Em, the extent of which was dependent on Cd concentration and time of treatment with Cd2+. Hyperpolarization of Em induced by FC was suppressed in the presence of Cd2+ at 1000 μM but not Cd2+ at 100 μM. It was also found that treatment of maize coleoptile segments with 30 mM TEA chloride caused hyperpolarization of Em and decreased Cd2+ content in coleoptile segments, suggesting that, in the same way as for FC, accumulation of Cd2+ was dependent on plasma membrane (PM) hyperpolarization. Similar to FC, TEA chloride also decreased Ca2+ content in coleoptile segments. La and Ver combined with Cd2+ (100 μM) significantly decreased Cd content in maize coleoptile segments, but only La completely abolished the toxic effect of Cd2+ on endogenous growth and growth in the presence of FC. Taken together, these results suggest that the mechanism by which FC counteracts the toxic effect of Cd2+ (except at 1000 μM Cd2+) on the growth of maize coleoptile segments involves both stimulation of PM H+-ATPase activity by FC as well as Cd2+-permeable, voltage-dependent Ca channels, which are blocked by FC and TEA chloride-induced PM hyperpolarization
Expression, localization and function of galectin-8, a tandem-repeat lectin, in human tumors
Galectin-8 (Gal-8) is a ‘tandem-repeat’-type
galectin, which possesses two carbohydrate recognition
domains connected by a linker peptide. Gal-8
complexity is related to the alternative splicing of its
mRNA precursor, which is known to generate isoforms.
Regarding its carbohydrate-binding specificity, Gal-8
has a unique feature among galectins, since its Cterminal
domain has higher affinity for N-glycan-type
branched oligosaccharides, while its N-terminal domain
shows strong affinity for α2-3-sialylated or 3’-sulfated
ß-galactosides. We integrate here the available
information on Gal-8 expression in different tumor types
and attempt to elucidate associations of its expression
and localization during tumor progression with the
overarching goal of analyzing its potential applications
in diagnosis and prognosis. Differential diagnosis is still
a prime concern in tumor pathology, and Gal-8 could be
of great value in some types of primary or secondary
tumors (i.e. papillary thyroid carcinoma, advanced colon
carcinoma from patients with distant metastases, or
metastases from primary lung carcinoma). The
prognostic value of Gal-8 has been described for
laryngeal carcinoma as well as advanced colon
carcinoma. Further studies are needed to explain the
relevance of Gal-8 and its isoforms in tumor pathology
and their different intra- or extracellular roles
(cytoplasmic, nuclear or extracellular) in tumor biology
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