Investigating seasonal metal impact on Stramonita haemastoma gastropod along the Algerian East Coast: Understanding through various pollution indicators

The main objective of this study was to assess the impact of environmental pollution on the gastropod Stramonita haemastoma by examining various physiological and biochemical parameters. Trace metal elements (TME) were measured in the snail's foot. Over a one-year period from 2013 to 2014, the study investigated the variations in reduced glutathione, malondialdehyde, metallothionein, glutathione S-transferase, acetylcholinesterase and catalase activities in the foot of the gastropod at three different sites. The results showed spatiotemporal fluctuations in biomarkers, physiological parameters and TME. This integrative approach, being the first of its kind in the region using S. haemastoma as a model organism, represents a means of environmental assessment accessible to all countries allowing the monitoring and conservation of coastal marine environments on a national and international scale and which could be used in marine biomonitoring programs to indicate the impact of pollution and assess the quality of the Algerian coastal marine environment.

Appraisal of Abelmoschus esculentus L. Response to Aluminum and Barium Stress

Trace metal element (TME) pollution is a major threat to plants, animals and humans. Agricultural products contaminated with metals may pose health risks for people; therefore, international standards have been established by the FAO/WHO to ensure food safety as well as the possibility of crop production in contaminated soils. This study aimed to assess the accumulating potential of aluminum and barium in the roots, shoots and fruits of Abelmoschus esculentus L., and their effect on growth and mineral nutrition. The content of proline and some secondary metabolites was also evaluated. After treating okra plants with aluminum/barium (0, 100, 200, 400 and 600 µM) for 45 days, the results showed that Al stimulated the dry biomass production, whereas Ba negatively affected the growth and the fructification yield. The okra plants retained both elements and exhibited a preferential accumulation in the roots following the sequence: roots > shoots > fruits, which is interesting for phytostabilization purposes. Al or Ba exposure induced a decline in mineral uptake (K, Ca, Mg, Zn and Fe), especially in roots and shoots. In order to cope with the stress conditions, the okra plants enhanced their proline and total phenol amounts, offering better adaptability to stress.

Diversification of Vascular Occlusions and Crystal Deposits in the Xylem Sap Flow of Five Tunisian Grapevines

Xylem vessels are essential pivotal organs in bulk hydraulic flow through the whole woody plant. However, environmental constraints generate disagreements in xylem structures, which are characterized by air emboli and occlusions formations, compromising water conductivity in grapevines. The aim of this work was to explore xylem morphology dynamics through the xylem sap flow of five Tunisian grapevine cultivars during the natural bleeding sap periods of 2019, 2021, and 2022. In fact, Sakasly, Khamri, Hencha, Razegui1, and Razegui2 rain-fed grapevine cultivars revealed differential responses towards xylem sap movement. The results demonstrated that the xylem sap flow was significantly more abundant in 2019 than 2021 and 2022 bleeding sap campaigns. A variation was revealed between the cultivars regarding the xylem sap flow. In fact, Sakasly gave the best xylem flow during the three campaigns. Razegui1 and Razegui2 registered approximately similar xylem sap flow, while Hencha and Khamri present the lowest sap fluxes during the three campaigns. Moreover, several vascular occlusions forms were identified from stem cross sections using environmental scanning electron microscopy (ESEM), including tyloses, gels, starch, and gum deposits. The highest occlusion number was observed in Sakasly, Razegui1, and Razegui2 cultivars. Among different biogenic calcium shapes, several were observed for the first time in grapevine, including multi-faceted druse, cubic, crystalline sand, styloids, spherical, or drop-like structures. Considering their lower flow and totally blocked vessels, both Hencha and Khamri confirmed their susceptibility to environmental constraints. However, Sakasly, Razegui1, and Razegui2 cultivars presented higher tolerance according to their sap flow and xylem morphology.

Assessment of Tolerance to Lanthanum and Cerium in Helianthus Annuus Plant: Effect on Growth, Mineral Nutrition, and Secondary Metabolism

Rare earth elements (REEs) present a group of nonessential metals for the growth and development of plants. At high concentrations, they can induce internal stress and disturb the physiological and biochemical mechanisms in plants. The potential uptake of lanthanum (La) and cerium (Ce) by the horticultural plant Helianthus annuus and the effect of these elements on its growth, its absorption of macroelements, and the contents of phenolic compounds and flavonoids were assessed. The plants were exposed to 0, 1, 2.5, 5, and 10 µM of La and Ce for 14 days. The results showed a remarkable accumulation of the two REEs, especially in the roots, which was found to be positively correlated with the total phenolic compound and flavonoid content in the plant shoots and roots. The plant's growth parameter patterns (such as dry weight and water content); the levels of potassium, calcium, and magnesium; and the tolerance index varied with the concentrations of the two studied elements. According to the tolerance index values, H. annuus had more affinity to La than to Ce. Although these metals were accumulated in H. annuus tissues, this Asteraceae plant cannot be considered as a hyperaccumulator species of these two REEs, since the obtained REE content in the plant's upper parts was less than 1000 mg·Kg^-1 DW.

Behavior of Cucumis sativus L. in presence of aluminum stress: Germination, plant growth, and antioxidant enzymes

Aluminum (Al) is an ubiquitously present element in soil; it is considered as a major problem in crop production that affects plant growth and development on acid soils. The aim of this work was to determine the germination parameters, to quantify the water status and growth, to assess the Al accumulation, and antioxidant enzyme activities in plants to evaluate the stress exerted by aluminum in Cucumis sativus L. For germination test, increasing doses of Al were used (0, 200, 500, 1,000, and 2,000 μM). Results showed that germination was stimulated with 500 of Al. Aluminum effects on development were studied by treating the plants with different concentrations of Al (100, 200, 300, and 500 µM, Al) during 45 days. As regards to the plant's growth, water content, and dry biomass production there was a slight increase. On the other hand, the activities of the antioxidant enzymes were disturbed by aluminum stress. Data indicate that the catalase (CAT) activity showed a decrease in the different parts of the plant. However, guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activities were significantly stimulated. Studying the effects of Al-induced stress allowed us to conclude that cucumber has a high ability to accumulate this element in the roots.

Assessing of growth, antioxidant enzymes, and phytohormone regulation in Cucurbita pepo under cadmium stress

One of the major problems worldwide is soil pollution by trace metal elements, which limits plant productivity and threatens human health. In this work, we have studied the effect of different concentrations of cadmium on Cucurbita pepo plants, evaluating different physiological and biochemical parameters: hormone signaling, metabolite concentration (malondialdehyde and hydrogen peroxide) and, in addition, the antioxidant enzyme activities of catalase and superoxide dismutase were evaluated. The production of biomass decreased under the Cd-stress. The results showed that C. pepo accumulates higher amounts of Cd2+ in roots than in shoots and fruits. Cd2+ differently affected the content of endogenous phytohormones. Furthermore, data suggest an essential involvement of roots in the regulation of tolerance to trace elements. As a result, indole acetic acid content increased in roots of treated plants, indicating that this phytohormone can stimulate root promotion and growth under Cd-stress. Similarly, salicylic acid content in roots and shoots increased in response to Cd2+, as well as abscisic acid levels in roots and fruits. In roots, the rambling accumulation pattern observed for jasmonic acid and salicylic acid suggests the lack of a specific regulation role against trace element toxicity. The activity of catalase and superoxide dismutase decreased, disrupted by the metal stress. However, the proline, malondialdehyde and hydrogen peroxide content significantly increased in Cd2+in all the analyzed tissues of the stressed plants. All these data suggest that C. pepo plants are equipped with an effective antioxidant mechanism against oxidative stress induced by cadmium up to a concentration of 500 μM.

Barium effect on germination, plant growth, and antioxidant enzymes in Cucumis sativus L. plants

Barium (Ba) is a nonessential element that can cause several deleterious effects in most organisms. Elevated Ba concentrations can be toxic for plants and may affect growth and disturbances in homeostasis. This study aimed to evaluate the Ba stress, the plant-tolerance limits, and the detoxification strategy adopted by Cucumis sativus L. The effect of Ba on seed's germination and vegetative development of this species was evaluated. For germination test, different Ba concentrations were used (0, 200, 500, 1,000, and 2,000 μM). Results showed that germination was stimulated with 500 and 2,000 µM of Ba. The toxicity effect on plant development was studied by treating the plants with increasing doses of Ba (100, 200, 300, and 500 μM) during 45 days. Shoot and root dry biomass production decreased significantly with elevated Ba concentrations, although water content enhanced in the roots. The concentration of Ba, 500 µM, induced high Ba accumulation in shoots and roots (9 times higher than in the control plants). Moreover, results showed that catalase, guaiacol peroxidase, and ascorbate peroxidase activities were stimulated in the different tissues of cucumber plants which highlight the occurring of an oxidative damage through Ba treatments and the involvement of the plant enzymatic antioxidant defense system.

Alleviated Actions of Plantago albicans Extract on Lead Acetate-Produced Hepatic Damage in Rats Through Antioxidant and Free Radical Scavenging Capacities

The aim of this study was to explore the possible protective mechanisms and to determine the antioxidant capacity of phenolic compounds extracted from Plantago albicans against lead acetate-induced hepatic injury. High performance liquid chromatography-photo diode array/electrospray ionization-mass spectrometry (HPLC-PDA/ESI-MS) assay was used to identify the P. albicans extract phenolic compounds. Animals received 100 mg of lead acetate/kg of body weight (bw) in the drinking water for a period of 30 days. The other groups of rats were orally administered with silymarin (300 mg/kg bw) or the P. albicans extract at two doses (100 and 300 mg/kg of bw), once daily, by gastric gavage for the same time. The P. albicans exhibited high total phenolic, flavonoid, and anthocyanin contents. The antioxidant in vitro activity demonstrated that the P. albicans exhibits an important effect against deleterious reactive species. The in vivo results showed that P. albicans prevented the lead acetate-induced significant changes on serum and liver lipid levels. In contrast, P. albicans succeeded in improving the biochemical parameters of serum and liver bringing them closer to the normal values of the control group. It also significantly promoted (P < .05) pro-inflammatory cytokines (TNF-α, IL-6, and NF-κB) in the liver of the experimental animals. The evaluated sample with HPLC-PDA/ESI-MS method showed to contain 10 dominant polyphenols, 2 hydroxycinnamic acids (p-coumaric acid and chlorogenic acids), 4 flavones (Apigenin, Luteolin, Cirsiliol, and Luteolin-7-O-rutinoside), and an anthocyanin (cyanidin-3-glucoside). Hence, it can be concluded that P. albicans could be a potent source of health-beneficial phytochemicals providing a novel therapy to protect liver against lead exposure.

Multi-biomarkers approach to the assessment of the southeastern Mediterranean Sea health status: Preliminary study on Stramonita haemastoma used as a bioindicator for metal contamination

The present study aimed to evaluate the responses of different biochemicals parameters associated with environmental pollution in the digestive gland of the gastropod mollusc Stramonita haemastoma. Physiochemical parameters and trace metal elements (Copper (Cu), Zinc (Zn), Chromium (Cr), Cadmium (Cd) and Lead (Pb)) were measured in seawater. Spatiotemporal variations in reduced glutathione (GSH), malondialdehyde (MDA) and metallothionein (Mt) as well as the specific activities of glutathione S-transferase (GST) and catalase (CAT) were evaluated in digestive gland of this species during a one-year period in 2013-2014. Samples collection was conducted at three sites. The results obtained showed seasonal fluctuations in GST and CAT activities and in the rate of Mt content. In addition, intersite variations in GSH, MDA, Mt and CAT were recorded in individuals. Also, trace metal elements concentrations determined by season in the digestive gland revealed spatial and temporal variations for Cu and Zn but they are below the limit of detection for Cd and Pb. The highest values were generally recorded in spring for Cu and in winter for Zn. In this first regional study using in S. haemastoma as a model, the biomarkers measured were seen to be inducible parameters to evaluate the health state of the organism and the overall quality of the study sites.

Physiological and biochemical responses of Suaeda fruticosa to cadmium and copper stresses: growth, nutrient uptake, antioxidant enzymes, phytochelatin, and glutathione levels

Environmental pollution by trace metal elements (TMEs) is a serious problem worldwide, increasing in parallel with the development of human technology. The present research aimed to examine the response of halophytic species Suaeda fruticosa to oxidative stress posed by combined abiotic stresses. Plants have been grown for 1 month with an irrigation solution supplemented with 200 mM NaCl and 400 μM Cd(2+) or 400 μM Cu(2+). The level of glutathione (GSH), phytochelatins (PCs), and antioxidant enzyme activities [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] as well as lipid peroxidation was studied to see the stress exerted by the TME and the level of tolerance and detoxification strategy adopted by S. fruticosa. Relative growth rate (RGR) decreased under Cd(2+) stress in this species, whereas Cu(2+) did not have any impact on S. fruticosa performance. Cd(2+) or Cu(2+) enhanced malondialdehyde, suggesting reactive oxygen species-induced disruption of membrane integrity and oxidative stress in S. fruticosa. On the other hand, the activities of the antioxidant enzymes CAT, APX, and GPX diminished and mineral nutrition was disturbed by metal stress. S. fruticosa was able to synthesize PCs in response to TME toxicity. However, data indicate that GSH levels underwent a significant decrease in roots and leaves of S. fruticosa stressed by Cd(2+) or Cu(2+). The GSH depletion accompanied by the increase of phytochelatin concentration suggests the involvement of GSH in the synthesis of phytochelatins.

Biophysical and biochemical constraints imposed by salt stress: learning from halophytes

Soil salinization is one of the most important factors impacting plant productivity. About 3.6 billion of the world's 5.2 billion ha of agricultural dry land, have already suffered erosion, degradation, and salinization. Halophytes are typically considered as plants able to complete their life cycle in environments where the salt concentration is above 200 mM NaCl. Salinity adjustment is a complex phenomenon but essential mechanism to overcome salt stress, with both biophysical and biochemical implications. At this level, halophytes evolved in several directions, adopting different strategies. Otherwise, the lack of adaptation to a salt environment would negatively affect their electron transduction pathways and the entire energetic metabolism, the foundation of every plant photosynthesis and biomass production. The maintenance of ionic homeostasis is in the basis of all cellular counteractive measures, in particular in terms of redox potential and energy transduction. In the present work the biophysical mechanisms underlying energy capture and transduction in halophytes are discussed alongside with their relation with biochemical counteractive mechanisms, integrating data from photosynthetic light harvesting complexes, electron transport chains to the quinone pools, carbon fixation, and energy dissipation metabolism.

Light-dark O2 dynamics in submerged leaves of C3 and C4 halophytes under increased dissolved CO2: clues for saltmarsh response to climate change

Waterlogging and submergence are the major constraints to which wetland plants are subjected, with inevitable impacts on their physiology and productivity. Global warming and climate change, as driving forces of sea level rise, tend to increase such submersion periods and also modify the carbonate chemistry of the water column due to the increased concentration of CO2 in the atmosphere. In the present work, the underwater O2 fluxes in the leaves of two abundant Mediterranean halophytes were evaluated at different levels of dissolved CO2. Photosynthetic enhancement due to increased dissolved CO2 was confirmed for both Halimione portulacoides and Spartina maritima, probably due to high tissue porosity, formation of leaf gas films and reduction of the oxygenase activity of Rubisco. Enhancement of the photosynthetic rates in H. portulacoides and S. maritima was concomitant with an increase in energy trapping and transfer, mostly due to enhancement of the carboxylation reaction of Rubisco, leading to a reduction of the energy costs for carbon fixation. Transposing these findings to the ecosystem, and assuming increased dissolved CO2 concentration scenarios, the halophyte community displays a new ecosystem function, increasing the water column oxygenation and thus reinforcing their role as principal primary producers of the estuarine system.