Transcriptomic hallmarks of in vitro TiO2 nanotubes toxicity in Chlamydomonas reinhardtii

Bio distribution and acute toxicity profiling of Pluronic F127 coated Titanium dioxide nanotubes in adult Wistar rats

Metal and metal oxide nanoparticles are gaining immense attention among researchers owing to their admirable application potentials in various therapeutic events. Titanium dioxide (TiO2) has been recognized as one of the leading candidates in this category and holds wide interest within the scientific community. Among the various morphological nanoforms of TiO2, nanotube is grabbing remarkable attention as they have succeeded as an active vehicle in various medical procedures like intravascular stenting, drug delivery, as biosensors etc. This ultimately demands toxicity profiling of nanotubes in various aspects. Present study elaborates a concept through which acute toxicity profiling of TiO2 nanotubes in adult Wistar rats is presented. TNTs were synthesized via solvo-thermal approach and surface coated with a biocompatible polymer; Pluronic-F127 (P-F127). This step assists in ameliorating the troubles associated with the nanomaterial dispersion stability. The experimental rats were intraperitoneally administered with TNT-P (10 mg/kg) and sacrificed on different time periods (3rd, 7th and 14th days). Biodistribution of the material was tracked in major tissues including brain, liver, spleen and kidneys. A set of acute toxicity studies was performed which comprises hematology evaluation, biochemical studies, antioxidant detection, analysis of urine parameters, immune modulation study and histopathology evaluation. Many of the experiments revealed an unaltered physiological response in rats; except for some biochemical and hematology parameters. Overall study suggests that, TNT-P do not result into a negative response in Wistar rats over 14 days.

Transcriptomics Reveals the Pathway for Increasing Brassica chinensis L. Yield under Foliar Application of Titanium Oxide Nanoparticles

In this study, Brassica chinensis L seedlings after 6 weeks of soil cultivation were treated with foliar application of TiO2 NPs (20 mg/L) for different times. Transcriptomics analysis was employed to investigate the impact of TiO2 NPs on the physiology, growth, and yield of B. chinensis L. Results showed that TiO2 NPs' exposure significantly increased the biomass, total phosphorus, and catalase enzyme activity by 23.60, 23.72, and 44.01%, respectively, compared to the untreated ones (not bulk or ion).TiO2 NPs increased the leaf chlorophyll content by 4.9% and photosynthetic rate by 16.62%, which was attributed to the upregulated expression of seven genes (PetH, PetF, PsaF, PsbA, PsbB, PsbD, and Lhcb) associated with electron transport in photosystem I and light-harvesting in leaves. The water balance of B. chinensis was improved correlating with the altered expressions of 19 aquaporin genes (e.g., PIP2;1 and NIP6;1). The expressions of 58 genes related to plant hormone signaling and growth were dysregulated, with notable downregulations in GA20, SnRK2, and PP2C and upregulations of DELLAs, SAM, and ETR. Moreover, the 11 tricarboxylic acid cycle genes and 13 glycolysis genes appear to stimulate pathways involved in promoting the growth and physiology of B. chinensis. This research contributes valuable insights into new strategies for increasing the yield of B. chinensis.

Mechanistic transcriptome comprehension of Chlamydomonas reinhardtii subjected to black phosphorus

Two-dimensional materials have recently gained significant awareness. A representative of such materials, black phosphorous (BP), earned attention based on its comprehensive application potential. The presented study focuses on the mode of cellular response underlying the BP interaction with Chlamydomonas reinhardtii as an algal model organism. We observed noticeable ROS formation and changes in outer cellular topology after 72 h of incubation at 5 mg/L BP. Transcriptome profiling was employed to examine C. reinhardtii response after exposure to 25 mg/L BP for a deeper understanding of the associated processes. The RNA sequencing has revealed a comprehensive response with abundant transcript downregulation. The mode of action was attributed to cell wall disruption, ROS elevation, and chloroplast disturbance. Besides many other dysregulated genes, the cell response involved the downregulation of GH9 and gametolysin within a cell wall, pointing to a shift to discrete manipulation with resources. The response also included altered expression of the PRDA1 gene associated with redox governance in chloroplasts implying ROS disharmony. Altered expression of the Cre-miR906-3p, Cre-miR910, and Cre-miR914 pointed to those as potential markers in stress response studies.

Impact of the combined effect of seawater exposure with wastewater and Fe2O3 nanoparticles on Chlorella vulgaris microalgae growth, lipid content, biochar, and bio-oil production

Microalgae is one the promising source of energy for the production of biofuel and other value-added products to replace the existing conventional fossil fuels. However, low lipid content and poor cell harvesting are the key challenges. Based on the growth conditions the lipid productivity will be affected. The current study examines the mixtures of both wastewater and NaCl on the microalgae growth was studied. The microalgae used for conducting the tests were Chlorella vulgaris microalgae. Mixtures of the wastewater was prepared under the different concentrations of the seawater, classified as S0%, S20%, and S40%. The growth of microalgae was studied in the presence of these mixtures, and the addition of Fe₂O₃ nanoparticles was included to stimulate the growth. The results showed that increasing the salinity in the wastewater resulted in decreased biomass production, but significantly increased lipid content compared to S0%. The highest lipid content was recorded at S40%N with 21.2%. The Highest lipid productivity was also witnessed for S40% with 45.6 mg/Ld. The cell diameter was also found to increase with increasing salinity content in the wastewater. The addition of Fe₂O₃ nanoparticles in the seawater was found to enhance the productivity of the microalgae extensively, resulting in 9.2% and 6.15% increased lipid content and lipid productivity respectively compared to conventional cases. However, the inclusion of the nanoparticles slightly increased the zeta potential of microalgal colloids, with no noticeable effects on the cell diameter or bio-oil yields. Based on these findings, Chlorella vulgaris was identified as a suitable candidate for treating wastewater with high salinity exposure.

Not so dangerous? PET microplastics toxicity on freshwater microalgae and cyanobacteria

Microalgae and cyanobacteria are among the most important primary producers and are responsible for the production of 50-80% of the oxygen on Earth. They can be significantly affected by plastic pollution, as the vast majority of plastic waste ends up in rivers and then the oceans. This research focuses on green microalgae Chlorella vulgaris (C. vulgaris), Chlamydomonas reinhardtii (C. reinhardtii), filamentous cyanobacterium Limnospira (Arthrospira) maxima (L.(A.) maxima) and how they are affected by environmentally relevant PET-MPs (polyethylene-terephtalate microplastics). Manufactured PET-MPs have asymmetric shape, size between 3 and 7 μm and were used in concentrations ranging from 5 mg/L to 80 mg/L. The highest inhibitory rate of growth was found in C. reinhardtii (-24%). Concentration-dependent changes in chlorophyll a composition were found in C. vulgaris and C. reinhardtii, not in L. (A.) maxima. Furthermore, cell damage was detected in all three organisms by CRYO-SEM (shriveling, cell wall disruption), but the cyanobacterium was the least damaged. A PET-fingerprint was detected on the surface of all tested organisms using FTIR, indicating the adherence of PET-MPs. The highest rate of PET-MPs adsorption was detected in L. (A.) maxima. Specifically, characteristic spectra were observed at ∼721, 850, 1100, 1275, 1342, and 1715 cm^-1 which are specific for functional groups of PET-MPs. Nitrogen and carbon content significantly increased in L. (A.) maxima under exposure to 80 mg/L due to the PET-MPs adherence and mechanical stress. In all three tested organisms, weak exposure-related ROS generation was detected. In general, cyanobacteria seem to be more resistant to the effects of MPs. However, organisms in the aquatic environment are exposed to MPs over a longer time scale, so it is important to use the present findings for further longer-term experiments on environmentally relevant organisms.