Effect of ultraviolet-B radiation on growth, photosynthetic pigments, and cell biology of Kappaphycus alvarezii (Rhodophyta, Gigartinales) macroalgae brown strain

Abstract

Kappaphycus alvarezii is a seaweed of great economic importance for the extraction of kappa carrageenan from its cell walls. The most common strains are dark red, brown, yellow, and different gradations of green. It is known that ultraviolet radiation (UVR) affects macroalgae in many important ways, including reduced growth rate, reduction of primary productivity, and changes in cell biology and ultrastructure. Therefore, we examined the brown strain of K. alvarezii exposed to ultraviolet-B radiaton (UVBR) for 3 h per day during 28 days of cultivation. The control plants showed growth rates of 7.27% d -1 , while plants exposed to UVBR grew only 4.0% d -1 . Significant differences in growth rates and in phycobiliproteins between control and exposed plants were also found. Compared with control plants, phycobiliprotein contents were observed to decrease after UV-B exposure. Furthermore, the chlorophyll a (Chl a) contents decreased and showed significant differences. UVBR also caused changes in the ultrastructure of cortical and subcortical cells, which included increased thickness of the cell wall and number of plastoglobuli, reduced intracellular spaces, changes in the cell contour, and destruction of chloroplast internal organization. Reaction with Toluidine Blue showed an increase in the thickness of the cell wall, and Periodic Acid-Schiff stain showed a decrease in the number of starch grains. By the significant changes in growth rates, photosynthetic contents and ultrastructual changes observed, it is clear that UVBR negatively affects intertidal macroalgae and, by extension, their economic viability.

Effects of Cadmium on Growth, Photosynthetic Pigments, Photosynthetic Performance, Biochemical Parameters and Structure of Chloroplasts in the Agarophyte <i>Gracilaria domingensis</i> (Rhodophyta, Gracilariales)

“…Chlorophyll a was extracted from approximately 1 g of tissue in 3 ml of dimethylsulfoxide (DMSO, Merck, Darmstadt, FRG) at 40˚C, during 30 min, using a glass tissue homogenizer [28,29]. Pigments were quantified spectrophotometrically according to Wellburn [30].…”

Effects of UV-B radiation on growth rates, pigment content and ultrastructure of red (wild type), greenish-brown and green strains ofGracilaria birdiae(Gracilariales, Rhodophyta)

“…Disintegration of the mitochondrial cristae induced by UV-B, observed in G. birdiae, has also been documented in other species, such as Palmaria palmata (Holzinger et al, 2004), P. decipiens (Poppe et al, 2003), and, to a lesser degree, Prasiola crispa . The lack of apparent damage to other cell structures, such as the nucleus and Golgi bodies, observed in this work and in I. cordata (Navarro et al, 2010a), G. domingensis (Schmidt et al, 2010c) and Kappaphycus alvarezii (Schmidt et al, 2009(Schmidt et al, , 2010a(Schmidt et al, , 2010b, suggests the existence of an efficient defence mechanism, preventing the destructive action of reactive oxygen species (ROS). These ROS may be responsible for the loss of cell membrane stability observed in chloroplasts and mitochondria exposed to UV-B by the action of lipid peroxidation (Kramer et al, 1991;Bowler et al, 1992;Jansen et al, 1996).…”

“…domingensis (Schmidt et al, 2010c), Iridaea cordata (Navarro et al, 2010b), and Kappaphycus alvarezii (Eswaran et al, 2001;Schmidt et al, 2010aSchmidt et al, , 2010b. Therefore, the presence of low concentrations of these pigments in the RD CE strain after exposure to UV-B suggests a possible use of these substances as a source of nutrients, since phycobiliproteins (mainly phycoerythrin) can act as nitrogen reserves when the demand for nitrogen is greater than the cellular and/or environmental availability (Gantt, 1990).…”

Comparison of extraction methods for selected carotenoids from macroalgae and the assessment of their seasonal/spatial variation

“…Carotenoid content in macroalgae is known to vary in some species according to season, while they can also differ in brown algae collected in different locations (Nomura et al, 2013). However, whilst several studies on the content of photosynthetic pigments of algae under investigation in the present study have been carried out (Aguilera et al, 2002;Gudrum, 2005;Sarojini, 2009;Schmidt et al, 2010), limited information is available on the seasonal changes that can occur. Considering any marine hydrobionts as a source of carotenoids or functional food components, determining the optimal period of harvesting algae with maximal content of these valuable substances is required.…”

“…In the present study the levels of fucoxanthin and xanthophyll over the period of a year from two harvest sites are presented in Tables 2 and 3. To date several studies on the content of photosynthetic pigments of algae have been carried out (Aguilera et al, 2002;Gudrum, 2005;Sarojini, 2009;Schmidt et al, 2010), however limited information is available on the seasonal changes that can occur in the species under investigation in the present study.…”