Changes in photosynthetic parameters and lipid classes of N-limited Ankistrodesmus densus (Chlorophyceae) under cadmium exposure

Rocha, Giseli Swerts; Parrish, Christopher C.; Espíndola, Evaldo Luiz Gaeta

doi:10.1007/s10811-022-02859-z

Cited by 4 publications

(3 citation statements)

References 40 publications

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“…The observed reduction in ETR may indicate a protective mechanism employed by S. falcatus (KU.B1) to mitigate the potential damage caused by excessive light. Microalgae often deploy various strategies to cope with high light stress, including thermal dissipation of excess energy (NPQ) and adjustments in the electron transport chain to optimize energy use [ 36 , 39 ]. The decrease in ETR might be a regulatory response to prevent overexcitation of the photosynthetic apparatus and to maintain a balance between energy absorption and utilization.…”

Section: Discussionmentioning

confidence: 99%

“…Tis intriguing observation implies that S. falcatus (KU.B1) may have developed an efcient repair cycle, enabling rapid turnover of damaged PSII components in response to heightened light intensity and maintaining optimal photosynthetic efciency [36]. NPQ provides insights into the intra-thylakoid pH gradient and the chloroplasts' capacity to disperse excessive excitation energy as heat, which corresponds linearly to energy dissipation, efectively protecting cells from photodamage [36,39]. Our investigation revealed that S. falcatus (KU.B1) cultivated under high light at 1000 μmol photons m − 2 •s − 1 exhibited minimal NPQ induction, suggesting that S. falcatus (KU.B1) may have efciently adapted to manage the intense light environment possibly due to the accumulation of substantial carotenoid quantities.…”

Section: Chlorophyll Fluorescencementioning

confidence: 99%

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Light Influences the Growth, Pigment Synthesis, Photosynthesis Capacity, and Antioxidant Activities in Scenedesmus falcatus

Songserm,

Nishiyama,

Sanevas

2024

Scientifica

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Light plays a significant role in microalgae cultivation, significantly influencing critical parameters, including biomass production, pigment content, and the accumulation of metabolic compounds. This study was intricately designed to optimize light intensities, explicitly targeting enhancing growth, pigmentation, and antioxidative properties in the green microalga, Scenedesmus falcatus (KU.B1). Additionally, the study delved into the photosynthetic efficiency in light responses of S. falcatus. The cultivation of S. falcatus was conducted in TRIS-acetate-phosphate medium (TAP medium) under different light intensities of 100, 500, and 1000 μmol photons m−2·s−1 within a photoperiodic cycle of 12 h of light and 12 h of dark. Results indicated a gradual increase in the growth of S. falcatus under high light conditions at 1000 μmol photons m−2·s−1, reaching a maximum optical density of 1.33 ± 0.03 and a total chlorophyll content of 22.67 ± 0.2 μg/ml at 120 h. Conversely, a slower growth rate was observed under low light at 100 μmol photons m−2·s−1. However, noteworthy reductions in the maximum quantum yield (Fv/Fm) and actual quantum yield (Y(II)) were observed under 1000 μmol photons m−2·s−1, reflecting a decline in algal photosynthetic efficiency. Interestingly, these changes under 1000 μmol photons m−2·s−1 were concurrent with a significant accumulation of a high amount of beta-carotene (919.83 ± 26.33 mg/g sample), lutein (34.56 ± 0.19 mg/g sample), and canthaxanthin (24.00 ± 0.38 mg/g sample) within algal cells. Nevertheless, it was noted that antioxidant activities and levels of total phenolic compounds (TPCs) decreased under high light at 1000 μmol photons m−2·s−1, with IC50 of DPPH assay recorded at 218.00 ± 4.24 and TPC at 230.83 ± 86.75 mg of GAE/g. The findings suggested that the elevated light intensity at 1000 μmol photons m−2·s−1 enhanced the growth and facilitated the accumulation of valuable carotenoid pigment in S. falcatus, presenting potential applications in the functional food and carotenoid industry.

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Section: Discussionmentioning

confidence: 99%

Section: Chlorophyll Fluorescencementioning

confidence: 99%

Light Influences the Growth, Pigment Synthesis, Photosynthesis Capacity, and Antioxidant Activities in Scenedesmus falcatus

Songserm,

Nishiyama,

Sanevas

2024

Scientifica

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“…Nevertheless, it is still used today in routine estimation of cell culture concentrations (e.g. Pereira et al 2016;Sheward et al 2017;Rocha et al 2022) probably because of the lack of affordable, accurate and precise automatic alternatives in the market.…”

Section: Discussionmentioning

confidence: 99%

Counting microalgae cultures with a stereo microscope and a cell phone using deep learning online resources

2022

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Background This work presents an experience done to evaluate the number of very small objects in the field of view of a stereo microscope, which are usually counted by direct observation, with or without the use of grids as visual aids. We intend to show that deep learning recent algorithms like YOLO v5 are adequate to use in the evaluation of the number of objects presented, which can easily reach the 1000 s. This kind of algorithm is open-source software, requiring a minimum of skills to install and run on a regular laptop. We further intend to show that the robustness of these kinds of approaches using convolutional neural networks allowed for the use of images of less quality, such as the images acquired with a cell phone. Results The results of training the algorithm and counting microalgae in cell phone images were assessed through human curation in a set of test images and showed a high correlation, showing good precision and accuracy in detections. Conclusions This is a low-cost alternative available worldwide to many more facilities than expensive cameras and high-maintenance rigid set-ups, along with software packages with a slow learning curve, therefore enlarging the scope of this technique to areas of knowledge where the conditions of laboratory and human work are a limiting factor.

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Impacts of phosphorus limitation in the toxicity of environmental concentrations of lead and zinc in Raphidocelis subcapitata (Chlorophyceae)

Rocha,

Melão

2024

J Appl Phycol

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Microalgal metabolism is affected by the surrounding environment and nutrients such as phosphorus (P) and nitrogen (N) are essential for optimal metabolism, as well as trace amounts of essential metals such as zinc (Zn); although in higher doses than required, Zn can be toxic. Lead (Pb) is a non-essential metal that can harm organisms from different trophic levels. In the environment, algae are exposed to several stressors simultaneously and adapt their metabolism. In the present study, we evaluated P limitation combined with environmental concentrations of Zn or Pb to the freshwater microalga Raphidocelis subcapitata regarding growth, pigments production, and photosynthetic parameters. Our results indicate that P limitation affected the growth, pigments production, relative maximum electron transport rate (rETRmax), and saturation irradiance; while Pb altered growth, pigments production, and maximum quantum yield; and Zn affected pigment production, photochemical and non-photochemical quenching, and rETRmax. However, the combination of metal and P limitation resulted in synergistic responses, i.e., higher damages than the isolated stressors, in growth, maximum and effective quantum yield, and in the rapid light curve parameters. On the other hand, antagonism, i.e., lower damages than isolated stressors, was observed in pigments production and non-photochemical quenching, suggesting that algae activated defense mechanisms to cope with both stressors simultaneously. In addition, our results indicate an algal metabolism adjustment to P limitation and highlight the importance of considering physicochemical water characteristics when defining regulations of acceptable levels of metals in aquatic ecosystems.

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Changes in photosynthetic parameters and lipid classes of N-limited Ankistrodesmus densus (Chlorophyceae) under cadmium exposure

Cited by 4 publications

References 40 publications

Light Influences the Growth, Pigment Synthesis, Photosynthesis Capacity, and Antioxidant Activities in Scenedesmus falcatus

Light Influences the Growth, Pigment Synthesis, Photosynthesis Capacity, and Antioxidant Activities in Scenedesmus falcatus

Counting microalgae cultures with a stereo microscope and a cell phone using deep learning online resources

Impacts of phosphorus limitation in the toxicity of environmental concentrations of lead and zinc in Raphidocelis subcapitata (Chlorophyceae)

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