Unravelling joint cytotoxicity of ibuprofen and oxytetracycline on Chlamydomonas reinhardtii using a programmed cell death-related biomarkers panel.

Pharmaceutical active compounds (PhACs) are emerging contaminants that pose a growing concern due to their ubiquitous presence and harmful impact on aquatic ecosystems. Among PhACs, the anti-inflammatory ibuprofen (IBU) and the antibiotic oxytetracycline (OTC) are two of the most used compounds whose presence has been reported in different aquatic environments worldwide. However, there is still scarce information about the cellular and molecular alterations provoked by IBU and OTC on aquatic photosynthetic microorganisms as microalgae, even more if we refer to their potential combined toxicity. To test the cyto- and genotoxicity provoked by IBU, OTC and their binary combination on Chlamydomonas reinhardtii, a flow cytometric panel was performed after 24 h of single and co-exposure to both contaminants. Assayed parameters were cell vitality, metabolic activity, intracellular ROS levels, and other programmed cell death (PCD)-related biomarkers as cytoplasmic and mitochondrial membrane potentials and caspase-like and endonuclease activities. In addition, a nuclear DNA fragmentation analysis by comet assay was carried out. For most of the parameters analysed (vitality, metabolic activity, cytoplasmic and mitochondrial membrane potentials, and DNA fragmentation) the most severe damages were observed in the cultures exposed to the binary mixture (IBU+OTC), showing a joint cyto- and genotoxicity effect. Both PhACs and their mixture caused a remarkable decrease in cell proliferation and metabolic activity and markedly increased intracellular ROS levels, parallel to a noticeable depolarization of cytoplasmic and mitochondrial membranes. Moreover, a strong increase in both caspase and endonuclease activities as well as a PCD-related loss of nuclear DNA integrity was observed in all treatments. Results analysis showed that the PhACs caused cell death on this non-target organism, involving mitochondrial membrane depolarization, enhanced ROS production and activation of PCD process. Thus, PCD should be an applicable toxicological target for unraveling the harmful effects of co-exposure to PhACs in aquatic organisms as microalgae.

Cytotoxicity of BP-3 and BP-4: Blockage of extrusion pumps, oxidative damage and programmed cell death on Chlamydomonas reinhardtii.

The health concern associated with the dangers related to exposure to UV radiation has led to an increase in the use of sunscreens containing UV-filters that can reach aquatic environments and possibly affect ecosystems. Benzophenone-3 (BP-3) and benzophenone-4 (BP-4) are two of the most used UV-filters. In the present work, the microalga Chlamydomonas reinhardtii was exposed to several concentrations of both chemicals. To evaluate their potential cytotoxicity on microalgal cells, different parameters were analysed including fast response biomarkers (increase in intracellular free Ca2+) as well as biomarkers related with the presence of oxidative stress (lipid peroxidation), energy metabolism (photosynthetic yield and cytoplasmic lipid accumulations), cell division (proliferation and F-actin content), programmed cell death (PCD) (caspase activation and DNA fragmentation) and possible mechanisms of resistance to xenobiotics (operation of extrusion pumps and presence of autophagic vacuoles). Results showed an increment of the percentage of cells with cytosolic free Ca2+ that could act as a secondary messenger in response to the stress. A decrease in photosynthetic yield and an increase in cytoplasmic lipid accumulations and lipid peroxidation levels were also detected. In addition, a decrease in cell proliferation was observed, linked to a decrease in the percentage of cells with F-actin. The increase observed in the microalgal population with caspase activity, together with the DNA fragmentation and the alterations in the cytoskeleton, suggested the induction of processes linked to PCD. Moreover, a blockage of extrusion pumps, which could be related to the toxicity mechanism of these compounds, and an increase in autophagic vacuoles, as an attempt to repair the damage caused by benzophenones, were detected. Overall, these biomarkers indicate that both UV-filters can be a serious threat to non-target photosynthetic microorganisms in aquatic environments, although BP-3 affected C. reinhardtii more markedly.

Toxicity of bisphenol A on marine microalgae: Single- and multispecies bioassays based on equivalent initial cell biovolume.

Standardised microalgal toxicity assays are usually carried out with single-species cultures; however, multispecies bioassays are more faithful to environmental conditions. The aim of this study was to assess the toxicity of the emerging pollutant bisphenol A (BPA) in single- and multispecies bioassays with three marine microalgae (Tetraselmis suecica, Phaeodactylum tricornutum and Nannochloropsis gaditana) using an equivalent initial cell biovolume of each species. After conducting preliminary growth experiments on these microalgae, a BPA concentration of 1 mg L-1 was chosen to study the effects of this pollutant in uni- and multialgal cultures. Growth, cell viability, oxidative stress, and inherent cell properties (size, complexity and autofluorescence) were determined by flow cytometry after 24 h of exposure. Results showed that P. tricornutum was the most affected species in all analysed biomarkers in both single- and multispecies bioassays. However, in N. gaditana cultures no significant differences were observed in any of the parameters and conditions tested, indicating that this species was the least sensitive to BPA. Between the uni- and multialgal tests, significant differences were observed in controls and BPA treated cultures of P. tricornutum and T. suecica. Nevertheless, it seemed that the cells of these marine microalgae suffered a similar pattern of alterations in both toxicity tests.

Assessment of cytotoxicity biomarkers on the microalga Chlamydomonas reinhardtii exposed to emerging and priority pollutants.

Contamination of aquatic ecosystems linked to anthropogenic activity is currently a major concern; therefore, ecotoxicological studies are needed to assess its effect on organisms. The main objective of this study was to investigate the effects of different pollutants on microalgae in search of sensitive biomarkers that can promote a common cytotoxic response regardless of the contaminant. Cultures of the freshwater microalga Chlamydomonas reinhardtii were exposed for 24 h to four chemicals, three emerging pollutants (benzophenone-3, bisphenol A and oxytetracycline) and one priority substance (atrazine). A cytometric panel was carried out to assess toxicity biomarkers including cellular growth, inherent cell properties, viability, vitality, cytoplasmic membrane potential and ROS levels. Lipid peroxidation, photosynthetic efficiency and transcriptional responses of photosynthesis- and oxidative stress-related genes using RT-qPCR were also studied. Some toxicity responses showed a similar pattern; a decrease in growth rate, vitality and photosynthetic efficiency and an increase in autofluorescence and in the number of cells with depolarised cytoplasmic membrane and were found for all chemicals tested. However, ATZ and OTC provoked a decrease in cell size, whereas BP-3 and BPA caused an increase in cell size, intracellular complexity and ROS levels and a decrease in cell viability. Assayed pollutants generally promoted an overexpression of genes related to cellular antioxidant defence system and a subexpression of photosynthesis-related genes. In addition to the traditional growth endpoint, cell vitality, autofluorescence and gene expression of catalase, glutathione peroxidase and Fe-superoxide dismutase were significantly affected for all chemicals tested, showing a common cytotoxic response. Among the tested substances, BP-3 provoked the strongest cytotoxic alterations on this microalga, pointing out that some emerging contaminants could be more harmful to organisms than priority pollutants.

Inequalities and risk factors related to non-participation in colorectal cancer screening programmes: a systematic review.

BACKGROUND: Colorectal cancer (CRC) screening programmes require high levels of participation in order to reduce mortality. To improve participation rates, it is necessary to identify the health risk factors and social inequalities associated with non-participation. METHODS: A systematic review was conducted between June and September of 2019 in six databases: CINHAL, Medline, Scopus, Social Sciences Citation Index, Embase and PsycINFO. Studies assessing the relationship between health risk factors, participation in preventive activities and participation in CRC screening were included. Methodological assessment was carried out according to the Quality Assessment Tools of the National Heart, Lung and Blood Institute. RESULTS: A total of nine studies that analyze participation in both organized and opportunistic screening programmes using any type of screening method were finally selected. Data were mainly self-reported although in two studies medical records were also studied. We identified several variables: gender, body mass index, consultation with a doctor or a specialist, educational level, employment, health insurance, residence, ethnicity, age, marital status, income, other preventive activities, obesity, physical activity, smoking, family history of CRC and general health status. CONCLUSION: The scarcity of studies linking risk factors, social inequalities and participation in preventive activities for participation in screening in the same study makes it difficult to reach definitive patterns related to non-participation in CRC screening programmes. Nevertheless, being under 60, obese, smoker and sedentary have shown an association with non-participation as well as not visiting a doctor.

Comparative acute toxicity of benzophenone derivatives and bisphenol analogues in the Asian clam Corbicula fluminea.

Among UV-filters, benzophenones are one of the most abundantly used and detected groups in the environment. Bisphenols are also one of the most widely used chemicals in plastics, but their demonstrated deleterious effects on several organisms and humans have led to the production of alternative analogues. However, few comparative studies on the ecotoxicological effects of these derivatives or analogues have been carried out. The present study aimed to investigate the effects of two benzophenones (BP-3 and BP-4) and two bisphenols (BPA and BPS) in a short-term exposure of the freshwater endobenthic bivalve Corbicula fluminea. Clams were exposed for 96 h to several concentrations of the four pollutants: BP-3 (0.63; 1.25; 2.5; 5 mg l-1), BP-4 (4.75; 9.5; 19; 38 mg l-1), BPA (3.75; 7.5; 15; 30 mg l-1), and BPS (2.5; 5; 10; 20 mg l-1). The comparative acute toxicity of these pollutants was evaluated by the analysis of the post-exposure filtering capacity of clams, lipid peroxidation (LP) levels and the activity of the antioxidant enzymes catalase (CAT) and glutathione reductase (GR). After the exposure period, except for BP-4, the chemicals tested seemed to be detected by clams and provoked valve closure, decreasing filter-feeding in a concentration-dependent manner. Furthermore, C. fluminea exposed to the highest concentrations of BP-3, BP-4 and BPA showed a significant increase in LP, CAT and GR activities with respect to their controls. BP-3 and BPA were the most toxic compounds showing significant differences in all the parameters analysed at the highest concentrations assayed. However, clams exposed to BPS showed only significant alterations in filtration parameters and in GR activity, in the two highest concentrations tested, indicating that this compound was the least toxic to clams. Obtained results highlight the importance of investigating the effects that emerging pollutants have on aquatic organisms.

Effects of Bisphenol A on the microalga Chlamydomonas reinhardtii and the clam Corbicula fluminea.

Bisphenol A (BPA) is used throughout the world and it could enter aquatic ecosystems causing harmful effects on humans, animals and plants. The current study relies on the investigation of the toxicity of this emerging pollutant on two freshwater species from different trophic levels: the microalga Chlamydomonas reinhardtii and the clam Corbicula fluminea. After 96 h of exposure to several concentrations of BPA, the growth of C. reinhardtii was affected, being the 96 h-EC50 value for growth 30 mg L-1. The toxicity and bioaccumulation of 30 mg L-1 BPA in microalgae after 24 h of exposure were studied. Several cytotoxicity biomarkers such as vitality, oxidative stress and cytoplasmic membrane potential were altered in exposed cells and microalgae accumulated 0.16 pg BPA cell-1. Regarding C. fluminea, four treatments were established: control without BPA (C); BPA in the food (microalgae pre-exposed for 24 h to 30 mg L-1) (M); BPA in the water (7.5 mg L-1) (W); BPA in both food and water (M + W). After one month of exposure, treated bivalves showed a significantly decrease in the filtration rate and increased lipid peroxidation levels, indicating fitness reduction and oxidative damage. Furthermore, the activities of catalase, glutathione reductase, Se-dependent and total glutathione peroxidase enzymes increased significantly in W and M + W treatments with respect to the control. Clams of the M + W treatment were the most affected, indicating that the little amount of BPA bioaccumulated by microalgae could increase the damage. Emerging contaminants may accumulate in several organisms, such as microalgae, and could have negative impacts on ecosystems.

Do transparent exopolymeric particles (TEP) affect the toxicity of nanoplastics on Chaetoceros neogracile?

The potential presence of nanoplastics (NP) in aquatic environments represents a growing concern regarding their possible effects on aquatic organisms. The objective of this study was to assess the impact of polystyrene (PS) amino-modified particles (50  nm PSNH2) on the cellular and metabolic responses of the diatom Chaetoceros neogracile cultures at two essential phases of the growth cycle, i.e. exponential (division) and stationary (storage) phases. Both cultures were exposed for 4 days to low (0.05 µg mL-1) and high (5 µg mL-1) concentrations of PS-NH2. Exposure to NP impaired more drastically the major cellular and physiological parameters during exponential phase than during the stationary phase. Only an increase in ROS production was observed at both culture phases following NP exposures. In exponential phase cultures, large decreases in chlorophyll content, esterase activity, cellular growth and photosynthetic efficiency were recorded upon NP exposure, which could have consequences on the diatoms life cycle and higher food-web levels. The observed differential responses to NP exposure according to culture phase could reflect i) the higher concentration of Transparent Exopolymer Particles (TEP) at stationary phase leading to NP aggregation and thus, probably minimizing NP effects, and/or ii) the fact that dividing cells during exponential phase may be intrinsically more sensitive to stress. This work evidenced the importance of algae physiological state for assessing the NP impacts with interactions between NP and TEP being one key factor affecting the fate of NP in algal media and their impact to algal' cells.

Polystyrene microbeads modulate the energy metabolism of the marine diatom Chaetoceros neogracile.

Due to the growing concern about the presence of microplastics (MP) in the environment, the number of studies evaluating the toxicity of these small persistent particles on different marine species has increased in recent years. Few studies have addressed their impact on marine phytoplankton, a subject of great concern since they are primary producers of the aquatic food web. The aim of this study is to unravel the cytotoxicity of 2.5 µg mL-1 unlabelled amino-modified polystyrene beads of different sizes (0.5 and 2 µm) on the marine diatom Chaetoceros neogracile. In addition to traditional growth and photosynthesis endpoints, several physiological and biochemical parameters were monitored every 24 h in C. neogracile cells by flow cytometry during their exponential growth (72 h). Dynamic Light Scattering measurements revealed the strong aggregation and the negative charge of the beads assayed in the culture medium, which seemed to minimize particle interaction with cells and potentially associated impacts. Indeed, MP were not attached to the microalgal cell wall, as evidenced by scanning electron micrographs. Cell growth, morphology, photosynthesis, reactive oxygen species levels and membrane potential remained unaltered. However, exposure to MP significantly decreased the cellular esterase activity and the neutral lipid content. Microalgal oil bodies could serve as an energy source for maintaining a healthy cellular status. Thus, MP-exposed cells modulate their energy metabolism to properly acclimate to the stress conditions.

Differential toxicity of the UV-filters BP-3 and BP-4 in Chlamydomonas reinhardtii: A flow cytometric approach.

Due to the concern about the negative effects of exposure to sunlight, UV-filters are being introduced in all kind of cosmetic formulas. Wastewater treatment plants are not able to remove and/or degrade them; consequently they find their way into rivers, lakes and oceans. These chemicals are acquiring a concerning status due to their increasingly common use and the potential risk for the environment. Benzophenone-3 (BP-3) and Benzophenone-4 (BP-4) are broad-spectrum UV-filters used for the same purpose in personal care products, insecticides and plastic bags; however, after 96 h of exposure to several concentrations of these UV-filters, the growth of C. reinhardtii was more affected by BP-3 than by BP-4, being the 96 h-EC50 for growth 5 mg L-1 and 38 mg L-1, respectively. Based on these values Chlamydomonas reinhardtii cultures were exposed during 24 h to 2.5, 5 and 10 mg L-1 of BP-3 and 19, 38 and 76 mg L-1 of BP-4. A cytometric panel was carried out to evaluate the effect of sublethal concentrations of these UV-filters, thus several cytotoxicity biomarkers were analysed, including chlorophyll a fluorescence, viability, metabolic activity, oxidative stress, cytoplasmic and mitochondrial membrane potentials, and intracellular pH. BP-3 and BP-4 affect C.reinhardtii cells in a different way, showing differences for three of the examined parameters. Chlorophyll a fluorescence and mitochondrial membrane potential showed a significant increase (p < 0.05) in BP-3 and a significant decrease in BP-4, whereas viability only decreased significantly in the highest concentrations of BP-3. Regarding to the other parameters analysed, a similar pattern of cytotoxicity was observed. Growth rate, vital population and metabolic activity (esterase activity) and intracellular pH decreased significantly and cytoplasmic membrane potential and ROS levels increased significantly in cultures exposed to both pollutants.

Will temperature and salinity changes exacerbate the effects of seawater acidification on the marine microalga Phaeodactylum tricornutum?

To evaluate the effects related to the combination of potential future changes in pH, temperature and salinity on microalgae, a laboratory experiment was performed using the marine diatom Phaeodactylum tricornutum. Populations of this species were exposed during 48h to a three-factor experimental design (3×2×2) with two artificial pH values (6, 7.4), two levels of temperature (23°C, 28°C), two levels of salinity (34psu, 40psu) and a control (pH8, Temp 23°C, Sal 34psu). The effects on growth, cell viability, metabolic activity, and inherent cell properties (size, complexity and autofluorescence) of P. tricornutum were studied using flow cytometry. The results showed adverse effects on cultures exposed to pH6 and high temperature and salinity, being the inherent cell properties the most sensitive response. Also, linked effects of these parameters resulted on cell viability and cell size decrease and an increase of cell autofluorescence. The conclusions obtained from this work are useful to address the potential effects of climate change (in terms of changes on pH, salinity and temperature) in microalgae.

Cytotoxic effects of the proton pump inhibitor omeprazole on the non-target marine microalga Tetraselmis suecica.

Omeprazole (OMP) is one of the most commonly used drugs for the treatment of gastro-intestinal disorders. Although it is daily consumed in high quantities and commonly detected in waters worldwide, relatively little is known about its ecotoxicity. The aim of this study was to evaluate the potential acute toxicity of increasing concentrations of OMP on the marine microalga Tetraselmis suecica analysing several cytotoxicity biomarkers by flow cytometry after 24h of exposure. Results showed that OMP caused a decrease in growth and autofluorescence, an increase in cellular volume and intracellular complexity, hyperpolarization of cytoplasmic and mitochondrial membranes and intracellular acidification. In addition, large amounts of reactive oxygen species (ROS) were generated which resulted in a decrease in the percentage of the viable population. However, the viable population showed an increase in their metabolic activity as an early response to overcome the stress. In conclusion, OMP may affect proton pumps in non-target organisms such as microalgae; it disturbed pH homeostasis and provoked an early accumulation of ROS that resulted in a rapid cell death in cells exposed to the highest concentration assayed.

Hidrotórax como complicación de la derivación ventriculoperitoneal: caso clínico / Hydrothorax as a complication of a ventricle peritoneal shunt. A case report

La derivación ventriculoperitoneal (DVP) es el tratamiento habitual en caso de hidrocefalia. Se trata de una técnica sencilla y eficaz, pero hasta un 70% de los pacientes presentan algún tipo de complicación a lo largo de su vida. La mayoría de ellas son debidas a infección o disfunción mecánica, siendo las complicaciones torácicas poco frecuentes. El presente caso es uno de los pocos encontrados en la literatura en el que se objetiva hidrotórax como complicación de la DVP sin migración de la punta de catéter y sin ascitis. Describimos el caso de una niña de 2años con DVP. La paciente es diagnosticada de derrame pleural compatible con hidrotórax. Tras análisis de β2-transferrina en líquido pleural se comprobó que se trataba de líquido cefalorraquídeo. El TAC craneal mostró un catéter de DVP normoposicionado. La radiografía y la ecografía de abdomen mostraron punta de catéter bien situada en peritoneo

The ventricle peritoneal (VP) shunt is commonly used in the treatment of hydrocephalus. It is a relatively simple and effective technique, but around 70% of the patients with a VP shunt have a complication in their lifetime. Most of these complications are due to infection or mechanical dysfunction. The thoracic complications are rare. The present case is one of the small number of them found in the literature, describing hydrothorax as a complication of a VP shunt without catheter migration and without ascites. The case is presented of a 2 year-old girl with VP shunt. The patient was diagnosed with pleural effusion compatible with hydrothorax. After finding beta-2-transferrin in the pleural fluid, it was it was shown to be from cerebrospinal fluid. Cranial CT showed the catheter in a proper position, and the Xray and ultrasound showed the catheter correctly positioned in the peritoneum

Does a short-term exposure to atrazine provoke cellular senescence in Chlamydomonas reinhardtii?

The aim of this study was to investigate the impacts and modes of action of a chemical and nutrient deprivation on the cellular senescence process of Chlamydomonas reinhardtii. Several molecular and cellular parameters related to senescence phenomena were monitored in C. reinhardtii cells exposed for 24h to a sublethal concentration (0.25µM) of the herbicide atrazine and in unexposed 96h cells in an early stationary phase of growth. All endpoints showed the same pattern of response between treatments, except for the intracellular level of calcium, where a significant increase was observed in 24h-exposed cultures compared to 24h-log controls. Results also indicated that cell viability remained above 98% for all conditions. Reactive oxygen species (ROS) levels and caspase activity increased in all experimental cultures with respect to 24h-log controls and alterations in the nuclear morphology and cells with auto-phagosomes were observed in all treatments. However, a decrease in lipid peroxidation was detected which could be related to the observed increment of autophagic vacuoles that recycle damaged material, such as altered lipids in microalgal membranes. Furthermore, responses at the molecular level were also investigated. Gene transcription analyses, carried out by RT-qPCR technique, indicated an increase in transcripts for genes encoding glutathione S-transferase (GST) and ascorbate peroxidase (APX I) and a decrease for those encoding catalase (CAT), glutathione peroxidase (GPX) and Mn-superoxide dismutase (SOD-1) in both experimental treatments. Overall molecular and cellular results suggest that a short-term exposure to a sublethal concentration of atrazine may induce senescence features in microalgal cells which are the base of aquatic food webs.

[Hydrothorax as a complication of a ventricle peritoneal shunt. A case report]. / Hidrotórax como complicación de la derivación ventriculoperitoneal: caso clínico.

The ventricle peritoneal (VP) shunt is commonly used in the treatment of hydrocephalus. It is a relatively simple and effective technique, but around 70% of the patients with a VP shunt have a complication in their lifetime. Most of these complications are due to infection or mechanical dysfunction. The thoracic complications are rare. The present case is one of the small number of them found in the literature, describing hydrothorax as a complication of a VP shunt without catheter migration and without ascites. The case is presented of a 2 year-old girl with VP shunt. The patient was diagnosed with pleural effusion compatible with hydrothorax. After finding beta-2-transferrin in the pleural fluid, it was it was shown to be from cerebrospinal fluid. Cranial CT showed the catheter in a proper position, and the Xray and ultrasound showed the catheter correctly positioned in the peritoneum.

Flow cytometric assay to assess short-term effects of personal care products on the marine microalga Tetraselmis suecica.

Large quantities of personal care products (PCPs) are used daily and many of their chemical ingredients are subsequently released into marine environments. Cultures of the marine microalga Tetraselmis suecica were exposed for 24 h to three emerging compounds included in the main classes of PCPs: the UV filter benzophenone-3 (BP-3), the disinfectant triclosan (TCS) and the fragrance tonalide (AHTN). Concentrations tested, expressed as cellular quota (pg cell-1), ranged from 5 to 40 for BP-3, from 2 to 16 for TCS and from 1.2 to 2.4 for AHTN. A small cytometric panel was carried out to evaluate key cytotoxicity biomarkers including inherent cell properties, growth and metabolic activity and cytoplasmic membrane properties. BP-3 caused a significant increase in growth rate, metabolic activity and chlorophyll a fluorescence from 10 pg cell-1. However, growth and esterase activity decreased in cells exposed to all TCS and AHTN concentrations, except the lowest ones. Also these two compounds provoked a significant swelling of cells, more pronounced in the case of TCS-exposed cells. Although all treated cells remained viable, changes in membrane potential were observed. BP-3 and AHTN caused a significant depolarization of cells from 10 to 1.6 pg cell-1, respectively; however all TCS concentrations assayed caused a noticeable hyperpolarization of cells. Metabolic activity and cytoplasmic membrane potential were the most sensitive parameters. It can be concluded that the toxicological model used and the toxicological parameters evaluated are suitable to assess the toxicity of these emerging contaminants.

Early alterations on photosynthesis-related parameters in Chlamydomonas reinhardtii cells exposed to atrazine: A multiple approach study.

Chlamydomonas reinhardtii cells were exposed to a sublethal concentration of the widespread herbicide atrazine for 3h. Physiological cellular parameters, such as chlorophyll a fluorescence and oxidative stress monitored by flow cytometry and pigments levels were altered in microalgal cells exposed to 0.25 µM of atrazine. Furthermore, the effects of this herbicide on C. reinhardtii were explored using "omics" techniques. Transcriptomic analyses, carried out by RNA-Seq technique, displayed 9 differentially expressed genes, related to photosynthesis, between control cultures and atrazine exposed cultures. Proteomic profiles were obtained using iTRAQ tags and MALDI-MS/MS analysis, identifying important changes in the proteome during atrazine stress; 5 proteins related to photosynthesis were downexpressed. The results of these experiments advance the understanding of photosynthetic adjustments that occur during an early herbicide exposure. Inhibition of photosynthesis induced by atrazine toxicity will affect the entire physiological and biochemical states of microalgal cells.