Ultrastructural changes in Dunaliella minuta following acute and chronic exposure to copper and cadmium

Abstract

The ultrastructural changes taking place after short-term acute exposure to copper, cadmium and a combination of the two metals were examined. Additionally, the effects of long-term (8 months) exposure to ambient concentrations of these metals were investigated. Exposure to 0.34 microM cadmium affected the photosynthetic potential of this alga, by reducing the relative volume of the chloroplast by 23.27%. It also led to 74.6% increase in the relative volume of starch granules. Cells challenged with 0.34 microM cadmium and 7.57 microM copper had 33.49% larger volumes than controls, and their relative lipid volumes increased by 170%. In contrast, the relative volume of their pyrenoids decreased by 41.46%. Similar results were obtained after chronic exposure to 4.9 x 10(-4) microM copper with the relative volume of the pyrenoid being 28% smaller than the controls.

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

“…In the green alga Dunaliella minuta exposed to cadmium, Visviki and Rachlin [9] demonstrated a reduction in chloroplast volume and photosynthetic potential. Chlorophyll a levels decreased drastically in G. domingensis after exposure to cadmium.…”

“…Cd can attach to sulfated groups, as well as metalloproteins and metalloenzymes, thereby neutralizing their functions [13]. However, Cd has no nutritional value for algae [9].…”

“…Several studies have shown effects such as the decrease of macroalgae growth rates [2], increased activities of glutathione reductase [5], changes in photosynthetic pigments [1,6] and photosynthetic efficiency [2,6], as well as an increase in total proteins and lipid contents [1]. Finally, some reports have shown changes in the ultrastructure of the red algae Audouinella savina (F. S. Collins) Woelkerling [7] and Ceramium ciliatum (J. Ellis) Ducluzeau [8], Hypnea musciformis (Wulfen) Lamouroux [6]; the green algae Dunaliella minuta Lerche [9], Enteromorpha flexuosa (Wulfen) J. Agardh [10], Euglena gracilis Klebs [1], and the brown algae Padina gymnospora (Kützing) Sonder [11].…”

Influences of cadmium on fine structure and metabolism of Hypnea musciformis (Rhodophyta, Gigartinales) cultivated in vitro

“…Finally, some reports have shown changes in the ultrastructure of the red algae Audouinella savina (F.S. Collins) Woelkerling (Talarico 2002) and Ceramium ciliatum (J. Ellis) Ducluzeau (Diannelidis and Delivopoulos 1997); the green algae Dunaliella minuta Lerche (Visviki and Rachlin 1992), Enteromorpha flexuosa (Wulfen) J. Agardh (Andrade et al 2004) and Euglena gracilis Klebs (Rocchetta et al 2007); and the brown algae Padina gymnospora (Kützing) Sonde (Andrade et al 2002;.…”

“…Cd can bind to sulfated groups, as well as metalloproteins and metalloenzymes, thereby neutralizing their functions . However, Cd has no nutritive value for algae (Visviki and Rachlin 1992).…”