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

Abstract

The in vitro effect of cadmium on apical segments of Hypnea musciformis was examined. Over a period of 7 days, the segments were cultivated with different concentrations of cadmium, ranging from 50 to 300 μM. The samples were processed for microscopic and histochemical analysis of growth rates, content of photosynthetic pigments, and photosynthetic performance. Cadmium treatments increased cell wall thickness and the accumulation of plastoglobuli. Destruction of chloroplast internal organization was observed. Compared to controls, algae exposed to cadmium showed growth rate reduction, depigmentation, and blending in the lateral branches. The content of photosynthetic pigments, including chlorophyll a and phycobiliproteins, decreased after exposure to different concentrations of cadmium. These results agree with the decreased photosynthetic performance and relative electron transport rate observed after exposure of algae to cadmium. Taken together, these findings strongly indicate that cadmium negatively affects the architecture and metabolism of the carragenophyte H. musciformis, thus posing a threat to the economic vitality of this red macroalgae.

Cd Subcellular Localization in Root Tips of Hordeum vulgare

“…So metal-exposed plants can increase the amount of polysaccharides that bind heavy metal ions [24]. Santos et al [25] found that Cd increased cell wall thickness in Gracilaria domingensis treated with 100, 200, and 300 μM of Cd for 16 d, suggesting that such an increase in cell wall thickness can be interpreted as a defense mechanism against exposure to Cd [26]. It is probable that the activity of Dictyosomes more intense in plants exposed to Cd and that this results in the large production of vehicles, which then format the matrix content of the cell wall [26].…”

“…Santos et al [25] found that Cd increased cell wall thickness in Gracilaria domingensis treated with 100, 200, and 300 μM of Cd for 16 d, suggesting that such an increase in cell wall thickness can be interpreted as a defense mechanism against exposure to Cd [26]. It is probable that the activity of Dictyosomes more intense in plants exposed to Cd and that this results in the large production of vehicles, which then format the matrix content of the cell wall [26]. Cytochemical evidence also confi rms that cysteine-rich proteins, commonly referred to as phytochelatins, are localized in electron-dense granules in root cell walls of A. cepa [27], which seems to contribute substantially to Cd detoxifi cation.…”

Influence of cadmium and salinity in the red alga Pterocladiella capillacea: cell morphology, photosynthetic performance and antioxidant systems

“…This alteration in cellular metabolism of P. capillacea may be related to changes in the biosynthetic route of starch enzymes in the Calvin cycle, which is possibile by activating the degradation pathway signaling by oxidative stress condition by Cd toxicity. A decrease in starch grains and cell wall thickness was also observed in Hypnea musciformis (Wulfen) J. V. Lamouroux by Bouzon et al (2012) after Cd exposure, and these results were associated with morphological changes within the chloroplasts. Additionally, Huan et al (2014) observed a decline of starch in Ulva prolifera O. F. Müller under increasing salinity, assigning such alterations to a defense mechanism of rearrangement of biosynthetic metabolic pathways against environmental stresses.…”

“…Control and treated samples were attached on slides and sealed using colorless nail polish. A Leica HCX PLAPO lambda 639/1.4-0.6 oil immersion objective was fitted on the inverted fluorescent microscope (Bouzon et al 2012). Chloroplast autofluorescence was observed at 488 nm laser wavelength excitation with emission spectrum from 639 to 701 nm (Hepler and Gunning 1998).…”

Evaluation of impacts of climate change and local stressors on the biotechnological potential of marine macroalgae: a brief theoretical discussion of likely scenarios

“…Metals such as Zn or Cd already account for mortality among macroalgae (Bouzon et al, 2011); however, these effects are compounded by the impact of climate change, making the situation even more worrisome, as Russell et al (2009) have warned.…”