Zinc-supplementation (20?and and in at high irradiance. diatoms as other living organisms must find in their environment good conditions including the right range of macro- and microelements. Among the mandatory microelements required for cell functioning zinc (Zn) occupies a particular place because it acts as a structural component [2] and as functional component of numerous enzymes in some gene transcription regulators [3] and as a cofactor in zinc-finger protein involved in mitosis regulation [4] (for review see [5]). As for other nutrient Zn should be present within a definite range to allow optimum cell functioning and growth. In Zn-deficient conditions diatoms cannot develop whereas when Zn is present in excess crucial processes are inhibited partially or totally (growth: [6-8] photosynthesis: [9 10 while the oxidative stress develops [11-13]. Because the optimal range of Zn concentrations depends on diatom species this type of algae is used as bioindicators [14]. Physiological and biochemical studies have demonstrated that the capacity to tolerate Zn is linked to the ability to establish defense mechanisms (for reviews see [5 15 Among these mechanisms Zn chelation seems to be major. Zn ions can be chelated by exopolysaccharides as in the diatom [16] or in the cytoplasm by phytochelatins which are cysteine-rich pseudopeptides. Phytochelatins are synthesized by SCH-503034 addition of glutathione units (and were harvested and isolated from the South-East Vietnamese coast at the Can Gio site which is confronted by pollution from the Mekong River and two other diatom species (and often develops in polluted waters [18] and has been shown to be a tolerant species to UV [19 20 and Cu [10] but sensitive to Cd [14]. 2 Materials and Methods 2.1 Culture Conditions Kützing and (Kützing) Smith had been collected in the May Gio coastal site in South East Vietnam (latitude: 10°40′09′′; longitude: 107°00′59′′) whereas (Agardh) Kützing and (W. Smith) Reimer had been collected SCH-503034 for the French Atlantic coastline and were from the Nantes Tradition Collection (strains UTC58 and NCC18.2 resp.). Each taxon was axenically cultured in artificial seawater (ASW) ready from Millipore ultrapure drinking water based on Harrison et al. [21]. Diatoms from the Vietnamese coastline and through the People from france coastline were maintained in 16°C and 23°C respectively. The cultures had been lighted using cool-white fluorescent pipes (in a photon flux denseness of 300?waterproof light probe (Walz Germany) linked to a Li-Cor 189 quantum meter. The development temperatures were taken care of for measurements. For SCH-503034 experiments developing cells SCH-503034 were harvested from precultures centrifuged gently (900 exponentially?×g 10 4 and inoculated sterilely into fresh ASW supplemented or not having a sterile ZnCl2 share solution. The ultimate Zn focus was 20?had been measured based on Speziale et al spectrophotometrically. [22]. 2.3 Oxygen Evolution and Chlorophyll Fluorescence Measurements Oxygen evolution was determined utilizing a thermostated chamber built with a Clark-type air electrode (DW2 Hansatech Musical instruments SCH-503034 Ltd. UK). The air evolution was assessed under actinic irradiance which range Rabbit polyclonal to ZC3H14. from 0 to 1200?versus curves) were built in based on the style of Eilers and Peeters [23] utilizing the Sigma-plot software program. Chl fluorescence was assessed utilizing a FMS1 modulated fluorometer (Hansatech Ltd. UK) customized to create it ideal for make use of at low Chl concentrations [24]. To get the relative electron transportation price versus irradiance (rETR versus curves had been determined as indicated by Eilers and Peeters [23] and Mouget et al. [25]. 2.4 Carbonic Anhydrase Activity The carbonic anhydrase (CA) activity was measured based on Dionisio-Sese and Miyachi [26] and Morant-Manceau et al. [27]. Intact cells had been utilized to quantify the extracellular CA activity (CAext) while the total CA activity was quantified using cells homogenized in liquid nitrogen (CAtot). The internal CA activity (CAint?) was calculated as CAtot activity minus CAext activity. 2.5 Antioxidant Enzymatic Activities The algae were harvested by.