Impact of Pb on Chlamydomonas reinhardtii at Physiological and Transcriptional Levels.

Trace elements stress is one of the most damaging abiotic stresses in environment. Nevertheless, the defense mechanism in microalgae remains poorly understood. In this study, physiological and molecular methods were performed to analyze the defense responses in green alga Chlamydomonas reinhardtii. It was speculated that the defense responses might mainly be due to the regulation of hormone signaling, indicating its potential role in alleviating the Pb toxicity besides other physiological and molecular defense responses like decrease in growth rate, chlorophyll content and photosynthesis efficiency, intensification of antioxidative mechanisms, regulation of transcription factors, trace elements chelation, and sequestration into vacuole via trace elements transporters. The sole differentially expressed ATP-binding cassette (ABC) transporters indicated that ABC transporters might play a very important role in the transport and relocation of Pb in C. reinhardtii. Additionally, our data provide the required knowledge for future investigations regarding Pb toxicity and defense mechanisms in algae, and detection of trace elements pollution in environment.

Endoplasmic Reticulum-Mediated Protein Quality Control and Endoplasmic Reticulum-Associated Degradation Pathway Explain the Reduction of N-glycoprotein Level Under the Lead Stress.

Different anthropogenic activities result in the continuous increase of metal lead (Pb) in the environment and adversely affect living organisms. Therefore, it is important to investigate the tolerance mechanism in a model organism. Chlamydomonas reinhardtii is an important green eukaryotic model microalga for studying different kinds of biological questions. In this study, the responses of C. reinhardtii were revealed via a comprehensive approach, including physiological, genomic, transcriptomic, glycomic, and bioinformatic techniques. Physiological results showed that the growth rate and soluble protein content were significantly reduced under the high lead stress. Also, the results obtained from the genomic and transcriptomic analyses presented that the endoplasmic reticulum-mediated protein quality control (ERQC) system and endoplasmic reticulum-associated degradation (ERAD) pathway were activated under the third day of high lead stress. The unique upregulated protein disulfide isomerase genes on the ERQC system were proposed to be important for the protein level and protein quality control. The accumulation of specific N-glycans indicated that specific N-glycosylation of proteins might alter the biological functions of proteins to alleviate the Pb stress in alga and/or lead to the degradation of incomplete/misfolded proteins. At the same time, it was observed that genes involved in each process of ERAD were upregulated, suggesting that the ERAD pathway was activated to assist the degradation of incomplete/misfolded proteins. Therefore, it is reasonable to speculate that the reduction of protein level under the high lead stress was related to the activated ERQC system and QRAD pathway. Our findings will provide a solid and reliable foundation and a proposed ERAD working model for further in-depth study of the ERQC system and ERAD pathway under the Pb stress and even other biotic and abiotic stresses.

Unravelling property of polysaccharides from Sargassum sp. as an anti-wrinkle and skin whitening property.

In recent years, the natural ingredients are in high demand in formulating the cosmetic products. Seaweed polysaccharides signify the attractive natural ingredient with a wide range of functional properties that are expected for cosmeceutical formulations. The present work aimed to study the skin protection ability of polysaccharides extracted from Sargassum vachellianum (SvP), Sargassum horneri (ShoP) and Sargassum hemiphyllum (SheP). The extracted crude polysaccharides were characterized by HPLC and FTIR, which revealed that the polysaccharides are fucose-containing sulfated polysaccharides. Skin whitening and anti-wrinkling activity were analyzed by the ability to inhibit tyrosinase and elastase. The results revealed that the ShoP showed maximum tyrosinase inhibition (64.72 ±â€¯0.46%) and SvP exhibited considerable elastase inhibition (30.12 ±â€¯0.33%). The maximum moisture absorption (79.7 ±â€¯0.62%) and retention (68.99 ±â€¯0.64%) ability were observed in ShoP. The antioxidant activity was estimated by DPPH, superoxide radical scavenging, reducing power and total antioxidant activity. All the tested polysaccharides showed antioxidant activity in a dose-dependent manner, among them ShoP exhibited maximum total antioxidant (80.93 ±â€¯0.17%) and superoxide radical scavenging activity (67.4 ±â€¯0.42%) whereas SheP showed maximum DPPH radical scavenging activity (74.56 ±â€¯0.10%). Therefore, the present study indicates the potential of polysaccharides, ShoP, SvP and SheP as a promising cosmetic ingredient in cosmeceuticals.