Biochemical Responses of the Marine Macroalgae Ulva lactuca and Fucus vesiculosus to Cadmium and Copper - from Sequestration to Oxidative Stress

Abstract

Uiuversily ol' Plymouth. Drake Circus, Plymouth. PL4 8AA Higher plants and at lcast some yeasts, freshwater algae and marine diatoms respond to exposure to the toxic non essential heavy metal cadmium by synthesising glutathione-derived peptides with a high affinity for cadmium and some other heavy metals [ 1 -61. These peptides have the general formula gamm[EC]nG where n = 2 to 11 and are given the trivial name phytochelatins (PC) (if of plant origin) or cadystins (if derived from yeasts). Synthesis of these heavy metal chelating peptides is catalysed by the metal activated phytochelatin synthetase using substrate derived from the intracellular glutathione pool 1.31. The efficiency of metals as activators of phytochelatin synthetase varies with species but generally follows the sequence Cd2%u2%Zn2+ which is similar to the relative affinities of phytochelatins for the same ions [3]. Whereas sequestration of cadmium is a detoxification mechanism involving transport of Cd:PC complexes into vacuoles, the intracellular fate of Cu:PC and 2n:PC complexes is less clear. Formation of PC complexes with essential heavy metals may be [part ofl a metal homeostasis mechanism, with FC acting as a "chelation buffer". The role of PC in enabling plants to deal with toxic levels of essential heavy metals is not known but there is evidence that PC synthesis is not a primary response of plants to toxic levels of&+ or ZI?+ [41. Marine diatoms have been shown to have a good correlation between F C synthesis and normal environmental levels of cadmium [5.6]. In contrast, little is known about the situation in marine macroalgae. even though these species have been used as environmental biomonitoring organisms for some time 171. Past mining activities in the South West of England have resulted in areas of chronic heavy metal contamination of rivers, estuaries and coastal regions. The ubiquitous presence of species such as Fitcus vesiculosus and Ulva lacruca in both clean and contaminated sites provides an opportunity to investigate their biochemical responses to natural and laboratory exposure to heavy metals and to examine detoxification and tolerance mechanisms. This report concentrates on establishing the effects of exposing the above species to cadmium and copper under laboratory conditions. Fucus vesiculosus and Ulva laciuca were obtained from uncontaminated local sites, washed in clean artificial seawater [Instant Ocean, J & K Aquatics Ltd.]. kept in tanks of clean aerated artificial seawater for two weeks and then in artificial seawater containing CdSO4 [0.4 mg.l-I] (Fucus) or CuSO4 [O -0.92nig.l-I] (Ulva) for 1 week. Samples 14 grams] of algae were blotted dry, frozen in liquid nitrogen. ground in mortars and then extracted in 50mM pH 7.5 Tris/HCI buffer [Buffer A] (2cm3 buffer per gram tissue). Extracts were filtered through muslin and filtrates were clarified by centrifugation in a microcentrifuge [2 min. X 13,oOOgl.For metal-binding peptide purification, extracts of Fucus were applied to a column (2.5 X 1.5 cm) of QAE cellulo...

Copper accumulation, synthesis of ascorbate and activation of ascorbate peroxidase in Enteromorpha compressa (L.) Grev. (Chlorophyta) from heavy metal‐enriched environments in northern Chile

“…Another enzyme involved in buffering oxidative stress is GP, whose activity was not detected in E. compressa , regardless of the site of collection. This result deviates from that reported by Jervis et al . (1997) who, working with the close relative Ulva lactuca in laboratory experiments, found a clear response of GP to increasing copper concentrations.…”

“…2002), and desiccation related to the position of the organisms in the intertidal zone (Collén & Davison 1999a; Burritt, Larkindale & Hurd 2002). Similarly, metal‐induced oxidative stress in macro‐algae is also a poorly studied phenomenon and the few available cases have considered active oxygen scavenging enzymes other than AP (Jervis et al . 1997).…”

“…In algae, only a few reports concerning the mechanisms of copper tolerance are available. For example, copper toxicity activates AP in the green microalga Selenastrum capricornutum (Sauser, Liu & Wong 1997), GP in the green macroalga Ulva lactuca (Jervis, Rees‐Naesborg & Brown 1997) and decreases glutathione levels in Enteromorpha sp. (Rijstenbil et al .…”

The Long-Term Algae Extract (Chlorella and Fucus sp) and Aminosulphurate Supplementation Modulate SOD-1 Activity and Decrease Heavy Metals (Hg++, Sn) Levels in Patients with Long-Term Dental Titanium Implants and Amalgam Fillings Restorations

“…Some microalgae can remove heavy metals from wastewater. Chlorella vulgaris (CV) is a unicellular marine algae rich in chlorophyll (1–4%) that contains 55–67% protein, 9–18% dietary fiber, minerals, vitamins, and several oligoelements [17,22]. The CV algae are considered to be highly resistant to heavy metals and are widely used as a food supplement in Japan [17,23].…”

“…Chlorella protothecoides algae promote heavy metal detoxification in chlordecone poisoned-treated rats by reducing the half-life of the toxin from 40 to 19 days. In addition, the Fucus spiralis is a marine brown alga (spiral wrack) that contains phlorotannins (antioxidant) [22]. The phytochelatins are short produced peptides from plants, algae, and fungi in response to heavy metal exposure, which detoxificate heavy metals by its high cysteine-content.…”