Effect of arbuscular mycorrhizal symbiosis on growth and biochemical characteristics of Chinese fir (Cunninghamia lanceolata) seedlings under low phosphorus environment.

Background: The continuous establishment of Chinese fir (Cunninghamia lanceolata) plantations across multiple generations has led to the limited impact of soil phosphorus (P) on tree growth. This challenge poses a significant obstacle in maintaining the sustainable management of Chinese fir. Methods: To investigate the effects of Arbuscular mycorrhizal fungi (AMF) on the growth and physiological characteristics of Chinese fir under different P supply treatments. We conducted an indoor pot simulation experiment in the greenhouse of the Forestry College of Fujian Agriculture and Forestry University with one-and-half-year-old seedlings of Chinese fir from March 2019 to June 2019, with the two P level treatment groups included a normal P supply treatment (1.0 mmol L-1 KH2PO4, P1) and a no P supply treatment (0 mmol L-1 KH2PO4, P0). P0 and P1 were inoculated with Funneliformis mosseae (F.m) or Rhizophagus intraradices (R.i) or not inoculated with AMF treatment. The AMF colonization rate in the root system, seedling height (SH), root collar diameter (RCD) growth, chlorophyll (Chl) photosynthetic characteristics, enzyme activities, and endogenous hormone contents of Chinese fir were estimated. Results: The results showed that the colonization rate of F.m in the roots of Chinese fir seedlings was the highest at P0, up to 85.14%, which was 1.66 times that of P1. Under P0 and P1 treatment, root inoculation with either F.m or R.i promoted SH growth, the SH of R.i treatment was 1.38 times and 1.05 times that of F.m treatment, respectively. In the P1 treatment, root inoculation with either F.m or R.i inhibited RCD growth. R.i inhibited RCD growth more aggressively than F.m. In the P0 treatment, root inoculation with F.m and R.i reduced the inhibitory effect of phosphorus deficiency on RCD. At this time, there was no significant difference in RCD between F.m, R.i and CK treatments (p < 0.05). AMF inoculation increased Fm, Fv, Fv/Fm, and Fv/Fo during the chlorophyll fluorescence response in the tested Chinese fir seedlings. Under the two phosphorus supply levels, the trend of Fv and Fm of Chinese fir seedlings in different treatment groups was F.m > R.i > CK. Under P0 treatment, The values of Fv were 235.86, 221.86 and 147.71, respectively. The values of Fm were 287.57, 275.71 and 201.57, respectively. It increased the antioxidant enzyme activity and reduced the leaf's malondialdehyde (MDA) content to a certain extent. Conclusion: It is concluded that AMF can enhance the photosynthetic capacity of the host, regulate the distribution of endogenous hormones in plants, and promote plant growth by increasing the activity of antioxidant enzymes. When the P supply is insufficient, AMF is more helpful to plants, and R.i is more effective than F.m in alleviating P starvation stress in Chinese fir.

Sevelamer reverses liver fibrosis by deactivation of hepatic stellate cells.

Liver fibrosis is a chronic liver disease characterized by a progressive wound healing response caused by chronic liver injury. Currently, there are no approved clinical treatments for liver fibrosis. Sevelamer is used clinically to treat hyperphosphatemia and has shown potential therapeutic effects on liver diseases. However, there have been few studies evaluating the therapeutic effects of sevelamer on liver fibrosis, and the specific mechanisms are still unclear. In this study, we investigated the antifibrotic effects of sevelamer-induced low inorganic phosphate (Pi) stress in vitro and in vivo and analyzed the detailed mechanisms. We found that low Pi stress could inhibit the proliferation of activated hepatic stellate cells (HSCs) by promoting apoptosis, effectively suppressing the migration and epithelial-mesenchymal transition (EMT) of hepatic stellate cells. Additionally, low Pi stress significantly increased the antioxidant stress response. It is worth noting that low Pi stress indirectly inhibited the activation and migration of HSCs by suppressing transforming growth factor ß (TGF-ß) expression in macrophages. In a rat model of liver fibrosis, oral administration of sevelamer significantly decreased blood phosphorus levels, improved liver function, reduced liver inflammation, and increased the antioxidant stress response in the liver. Our study revealed that the key mechanism by which sevelamer inhibited liver fibrosis involved binding to gastrointestinal phosphate, resulting in a decrease in blood phosphorus levels, the downregulation of TGF-ß expression in macrophages, and the inhibition of HSC migration and fibrosis-related protein expression. Therefore, our results suggest that sevelamer-induced low Pi stress can attenuate hepatic stellate cell activation and inhibit the progression of liver fibrosis, making it a potential option for the treatment of liver fibrosis and other refractory chronic liver diseases.

Cyanobacterial blooms control with CaO2 in different stages: Inhibition efficiency, water quality optimization and microbial community changes.

This study explored the feasibility of calcium peroxide (CaO2) to inhibit cyanobacterial blooms of the outbreak and dormancy stages. Our previous studies have found that CaO2 has a high inhibitory effect on cyanobacteria. In order to explore the application effect of CaO2 in actual cyanobacteria lake water, we conducted this study to clarify the effect of CaO2 on inhibiting cyanobacteria in outbreak and dormancy stages. The results showed that CaO2 inhibited the growth of cyanobacteria in the outbreak and dormancy stages by 98.7% and 97.6%, respectively. The main inhibitory mechanism is: (1) destroy the cell structure and make the cells undergo programmed cell death by stimulating the oxidation balance of cyanobacteria cells; (2) EPS released by cyanobacteria resist stimulation and combine calcium to form colonies, and accelerate cell settlement. In addition to causing direct damage to cyanobacteria, CaO2 can also improve water quality and sediment microbial diversity, and reduce the release of sediment to phosphorus, so as to further contribute to cyanobacterial inhibition. Finally, the results of qRT-PCR analysis confirmed the promoting effect of CaO2 on the downregulation of photosynthesis-related genes (rbcL and psaB), microcystn (mcyA and mcyD) and peroxiredoxin (prx), and verified the mechanism of CaO2 inhibition of cyanobacteria. In conclusion, this study provides new findings for the future suppression of cyanobacterial bloom, by combining water quality, cyanobacterial inhibition mechanisms, and sediment microbial diversity.

Macrophage membrane (MMs) camouflaged near-infrared (NIR) responsive bone defect area targeting nanocarrier delivery system (BTNDS) for rapid repair: promoting osteogenesis via phototherapy and modulating immunity.

Bone defects remain a significant challenge in clinical orthopedics, but no targeted medication can solve these problems. Inspired by inflammatory targeting properties of macrophages, inflammatory microenvironment of bone defects was exploited to develop a multifunctional nanocarrier capable of targeting bone defects and promoting bone regeneration. The avidin-modified black phosphorus nanosheets (BP-Avidin, BPAvi) were combined with biotin-modified Icaritin (ICT-Biotin, ICTBio) to synthesize Icaritin (ICT)-loaded black phosphorus nanosheets (BPICT). BPICT was then coated with macrophage membranes (MMs) to obtain MMs-camouflaged BPICT (M@BPICT). Herein, MMs allowed BPICT to target bone defects area, and BPICT accelerated the release of phosphate ions (PO43-) and ICT when exposed to NIR irradiation. PO43- recruited calcium ions (Ca2+) from the microenvironment to produce Ca3(PO4)2, and ICT increased the expression of osteogenesis-related proteins. Additionally, M@BPICT can decrease M1 polarization of macrophage and expression of pro-inflammatory factors to promote osteogenesis. According to the results, M@BPICT provided bone growth factor and bone repair material, modulated inflammatory microenvironment, and activated osteogenesis-related signaling pathways to promote bone regeneration. PTT could significantly enhance these effects. This strategy not only offers a solution to the challenging problem of drug-targeted delivery in bone defects but also expands the biomedical applications of MMs-camouflaged nanocarriers.

Mechanisms of cadmium mitigation in tomato plants under orthophosphate and polyphosphate fertilization regimes.

Cadmium (Cd) is one of the most toxic elements in soil, affecting morphological, physiological, and biochemical processes in plants. Mineral plant nutrition was tested as an effective approach to mitigate Cd stress in several crop species. In this regard, the present study aimed to elucidate how different phosphorus (P) fertilization regimes can improve some bio-physiological processes in tomato plants exposed to Cd stress. In a hydroponic experiment, the impact of two phosphorus fertilizer forms (Polyphosphate (poly-P): condensed P-form with 100% polymerization rate and orthophosphate (ortho-P): from orthophosphoric acid) on the photosynthetic activity, plant growth, and nutrient uptake was assessed under three levels of Cd stress (0, 12, and 25 µM of CdCl2). The obtained results confirmed the negative effects of Cd stress on the chlorophyll content and the efficiency of the photosynthesis machinery. The application of poly-P fertilizer significantly improved the chlorophyll stability index (82%) under medium Cd stress (Cd12), as compared to the ortho-P form (55%). The analysis of the chlorophyll α fluorescence transient curve revealed that the amplitude of Cd effect on the different steps of electron transfer between PSII and PSI was significantly reduced under the poly-P fertilization regime compared to ortho-P, especially under Cd12. The evaluation of the RE0/RC parameter showed that the electron flux reducing end electron acceptors at the PSI acceptor side per reaction center was significantly improved in the poly-P treatment by 42% under Cd12 compared to the ortho-P treatment. Moreover, the use of poly-P fertilizer enhanced iron uptake and its stoichiometric homeostasis in the shoot tissue which maintained an adequate absorption of iron under Cd stress conditions. Findings from this study revealed for the first time that inorganic polyphosphate fertilizers can reduce Cd toxicity in tomato plants by enhancing photosynthesis activity, nutrient uptake, plant growth, and biomass accumulation despite the high level of cadmium accumulation in shoot tissues.

Impact of macronutrients and salinity stress on biomass and biochemical constituents in Monoraphidium braunii to enhance biodiesel production.

Microalgal lipids are precursors to the production of biodiesel, as well as a source of valuable dietary components in the biotechnological industries. So, this study aimed to assess the effects of nutritional (nitrogen, and phosphorus) starvations and salinity stress (NaCl) on the biomass, lipid content, fatty acids profile, and predicted biodiesel properties of green microalga Monoraphidium braunii. The results showed that biomass, biomass productivity, and photosynthetic pigment contents (Chl. a, b, and carotenoids) of M. braunii were markedly decreased by nitrogen and phosphorus depletion and recorded the maximum values in cultures treated with full of N and P concentrations (control, 100%). These parameters were considerably increased at the low salinity level (up to 150 mM NaCl), while an increasing salinity level (up to 250 mM NaCl) reduces the biomass, its productivity, and pigment contents. Nutritional limitations and salt stress (NaCl) resulted in significantly enhanced accumulation of lipid and productivity of M. braunii, which represented more than twofold of the control. Furthermore, these conditions have enhanced the profile of fatty acid and biodiesel quality-related parameters. The current study exposed strategies to improve M. braunii lipid productivity for biodiesel production on a small scale in vitro in terms of fuel quality under low nutrients and salinity stress.

Colonial Microcystis' biomass affects its shift to diatom aggregates under aeration mixing.

The effect of hydrodynamic mixing on controlling Microcystis blooms or changing the algal community to diatom dominance has been widely studied; however, the effects of colonial Microcystis biomass on the development of the algal community are poorly known. Here, in order to study the changes in Microcystis blooms under continuous aeration mixing, an experiment was carried out in a greenhouse with factors of varying biomass of Microcystis and inorganic nitrogen and phosphorus enrichment in summer. There were three chlorophyll a (Chl-a) levels in six treatments: low Chl-a level of 68.4 µg L-1 (treatments L, L-E), medium Chl-a level of 468.7 µg L-1 (treatments M, M-E), and high Chl-a level of 924.1 µg L-1 (treatments H, H-E). Treatments L-E, M-E and H-E were enriched with the same inorganic nitrogen and phosphorus nutrients. During the experiment of 30 days, the concentration of Microcystis and Chl-a decreased, and diatom Nitzschia palea cells appeared in all the treatments, which became dominant in treatments M, M-E, H and H-E, with the highest biomass of 9.41 ± 1.96 mg L-1 Nitzschia in treatment H-E on day 30. The rank order of the biomass of Nitzschia from low to high was (L = L-E) < (M = M-E) < H < H-E (P < 0.05). In addition, Nitzschia cells were aggregates attached to Microcystis colonies in all the treatments. The results showed that the initial biomass of colonial Microcystis affected the algal shift from Microcystis dominance to Nitzschia dominance. However, the enriched inorganic nitrogen and phosphorus was beneficial for the Nitzschia increase in the high biomass treatment alone. The shift from Microcystis dominance to diatom dominance under continuous aeration mixing may be caused by low light conditions as well as the nutrients released from Microcystis decay. Moreover, the aerobic condition caused by aeration mixing maintained the colonial mucilaginous sheath to support the growth of Nitzschia cells in aggregation. This study found for the first time that Microcystis blooms could shift to diatom Nitzschia dominance in aggregates. It provided a method to control and manipulate Microcystis blooms to diatom dominance through continuous aeration mixing to proper biomass of Microcystis colonies. The shift to diatoms dominance would provide more high quality food organisms for aquaculture and be beneficial to the material cycling and energy flowing in food web dynamics.

Uptake and cellular responses of Microcystis aeruginosa to PFOS in various environmental conditions.

Although PFOS has been banned as a persistent organic pollutant, it still exists in large quantities within the environment, thus impacting the health of aquatic ecosystems. Previous studies focused solely on high PFOS concentrations, disregarding the connection with environmental factors. To gain a more comprehensive understanding of the PFOS effects on aquatic ecosystems amidst changing environmental conditions, this study investigated the cellular responses of Microcystis aeruginosa to varying PFOS concentrations under heatwave and nutrient stress conditions. The results showed that PFOS concentrations exceeding 5.0 µg/L had obvious effects on multiple physiological responses of M. aeruginosa, resulting in the suppression of algal cell growth and the induction of oxidative damage. However, PFOS concentration at levels below 20.0 µg/L has been found to enhance the growth of algal cells and trigger significant oxidative damage under heatwave conditions. Heatwave conditions could enhance the uptake of PFOS in algal cells, potentially leading to heightened algal growth when PFOS concentration was equal to or less than 5.0 µg/L. Conversely, deficiency or limitation of nitrogen and phosphorus significantly decreased algal abundance and chlorophyll content, inducing severe oxidative stress that could be mitigated by exposure to PFOS. This study holds significance in managing the impact of PFOS on algal growth across diverse environmental conditions.

Phosphorus forms and zinc concentrations affect the physiological ecology and sinking rate of Thalassiosira weissflogii.

The combined effects of phosphorus (P) forms and zinc (Zn) concentrations on diatom silicification remain unclear. In this study, we investigate the effects of different Zn concentrations on the growth, cellular silicon content and sinking rate of Thalassiosira weissflogii under different P forms. The results showed that under the dissolved inorganic phosphorus (DIP) treatments, the specific growth rate of T. weissflogii in Zn limitation culture was significantly lower than that in Zn-replete culture. However, T. weissflogii cellular silicon content and sinking rate increased. Moreover, the reduced specific growth rate (7 %, p < 0.05), enhanced ALP activity (63 %, p < 0.05), and sinking rate (20 %, p < 0.05) for Zn-deplete T. weissflogii implied that the bioavailability of dissolved organic phosphorus (DOP) was depressed under Zn deplete medium. This study demonstrates that the physiological ecology and sinking rate of the diatom T. weissflogii were affected by both individual and combined changes in P forms and Zn concentrations.

Effects of Setaria viridis on heavy metal enrichment tolerance and bacterial community establishment in high-sulfur coal gangue.

Plant enrichment and tolerance to heavy metals are crucial for the phytoremediation of coal gangue mountain. However, understanding of how plants mobilize and tolerate heavy metals in coal gangue is limited. This study conducted potted experiments using Setaria viridis as a pioneer remediation plant to evaluate its tolerance to coal gangue, its mobilization and enrichment of metals, and its impact on the soil environment. Results showed that the addition of 40% gangue enhanced plant metal and oxidative stress resistance, thereby promoting plant growth. However, over 80% of the gangue inhibited the chlorophyll content, photoelectron conduction rate, and biomass of S. viridis, leading to cellular peroxidative stress. An analysis of metal resistance showed that endogenous S in coal gangue promoted the accumulation of glutathione, plant metal chelators, and non-protein thiols, thereby enhancing its resistance to metal stress. Setaria viridis cultivation affected soil properties by decreasing nitrogen, phosphorus, conductivity, and urease and increasing sucrase and acid phosphatase in the rhizosphere soil. In addition, S. viridis planting increased V, Cr, Ni, As, and Zn in the exchangeable and carbonate-bound states within the gangue, effectively enriching Cd, Cr, Fe, S, U, Cu, and V. The increased mobility of Cd and Pb was correlated with a higher abundance of Proteobacteria and Acidobacteria. Heavy metals, such as As, Fe, V, Mn, Ni, and Cu, along with environmental factors, including total nitrogen, total phosphorus, urease, and acid phosphatase, were the primary regulatory factors for Sphingomonas, Gemmatimonas, and Bryobacter. In summary, S. viridis adapted to gangue stress by modulating antioxidant and elemental enrichment systems and regulating the release and uptake of heavy metals through enhanced bacterial abundance and the recruitment of gangue-tolerant bacteria. These findings highlight the potential of S. viridis for plant enrichment in coal gangue areas and will aid the restoration and remediation of these environments.

Two-Dimensional Biodegradable Black Phosphorus Nanosheets Promote Large Full-Thickness Wound Healing through In Situ Regeneration Therapy.

Large full-thickness skin lesions have been one of the most challenging clinical problems in plastic surgery repair and reconstruction. To achieve in situ skin regeneration and perfect clinical outcomes, we must address two significant obstacles: angiogenesis deficiency and inflammatory dysfunction. Recently, black phosphorus has shown great promise in wound healing. However, few studies have explored the bio-effects of BP to promote in situ skin regeneration based on its nanoproperties. Here, to investigate whether black phosphorus nanosheets have positive bio-effects on in situ skin repair, we verified black phosphorus nanosheets' positive effects on angiogenic and anti-inflammatory abilities in vitro. Next, the in vivo evaluation performed on the rat large full-thickness excisional wound splinting model more comprehensively showed that the positive bio-effects of black phosphorus nanosheets are multilevel in wound healing, which can effectively enhance anti-inflammatory ability, angiogenesis, collagen deposition, and skin re-epithelialization. Then, multiomics analysis was performed to explore further the mechanism of black phosphorus nanosheets' regulation of endothelial cells in depth. Molecular mechanistically, black phosphorus nanosheets activated the JAK-STAT-OAS signaling pathway to promote cellular function and mitochondrial energy metabolism in endothelial cells. This study can provide a theoretical basis for applying two-dimensional black phosphorus nanosheets as nanomedicine to achieve in situ tissue regeneration in complex human pathological microenvironments, guiding the subsequent optimization of black phosphorus.

Phytic Acid-Promoted Exfoliation of Black Phosphorus Nanosheets for the Fabrication of Photothermal Antibacterial Coatings.

Medical device-associated infections (MDAI) caused by planktonic pathogens are of serious concern worldwide due to the emergence of drug resistance resulting from continuous overuse or misuse of antibiotics. Therefore, the design of non-antibiotics-based treatment for MDAI is of crucial importance. Black phosphorus (BP), a novel 2D material, has recently received much attention owing to its remarkable physical, chemical, mechanical, and functional features. However, the intricacy of the fabrication process has severely hampered the development of BP in prospective applications. In this study, a simple and eco-friendly liquid-phase exfoliation method of phytic acid (PA)-promoted exfoliation of BP nanosheets (PA@BP NSs) is developed for their potential application in antibacterial photothermal therapy. To impart the antimicrobial effects, the polydimethylsiloxane surfaces are functionalized with quaternized polymer (polyquaternium-2 or PQ) and PA@BP NSs, leading to the formation of PA-BP-PQ composite coatings. In addition to the contact-killing antibacterial effect of the cationic PQ, the PA-BP-PQ coating exhibits remarkable near-infrared irradiation-triggered bactericidal effects with low cytotoxicity both in vitro and in vivo. This study proposes a simple liquid-phase exfoliation technique for the fabrication of BP NSs and a one-step approach for the construction of PA-BP-PQ composite coatings for bi-modal (contact-killing and photothermal) antimicrobial therapy.

Markers of resistance to pea aphid, Acyrthosiphon pisum Harris in Pisum sativum L. accessions.

One of the major insect pests in Pisum sativum L. (is Acyrthosiphon pisum Harris (Hemiptera: pests in Pisum sativum L. (Hemiptera: Aphididae) is Acyrthosiphon pisum Harris (Hemiptera: Aphididae). An effective strategy for aphid control is the resistant host plant use. The current study aimed to identify resistance mechanisms and assess biochemical and morphological markers of pea aphid resistance in pea accessions. Meteorological variables affected the pea aphid density, which positively correlated with temperature, while precipitation amount and humidity negatively impacted. The aphid number was significantly and positively associated with the leaf area and the nitrogen content but negatively correlated with calcium and phosphorus levels. The pea aphid-resistant cultivars L 123-7-11, L 128-1and L 125-5 had small leaf areas, and high phosphorus and calcium content but a low nitrogen level. In the mutual influence of the plant indicators, phosphorus concentration had the highest negative impact on pea aphid density, followed by calcium. The plant marker inclusion in the pea breeding process is an efficient tool for a substantial selection program improvement for aphid resistance. Therefore, resistant host plants are essential tools promoting considerable selection program improvement for aphid resistance in the P. sativum breeding process and helping develop sustainable and environmentally friendly agriculture.

Leaf surface features of maize cultivars and response to foliar phosphorus application: effect of leaf stage and plant phosphorus status.

Soil phosphorus (P) application is the most common fertilisation technique but may involve constraints due to chemical fixation and microbial immobilisation. Furthermore, excessive P fertilisation leads to P runoff into water bodies, threatening ecosystems, so targeted foliar P fertilisation is an interesting alternative. This study aimed to determine the importance of leaf surface characteristics for foliar P uptake in P-deficient maize (Zea mays L.). The leaf surface of four maize cultivars was characterised by electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Uptake of foliar-applied P by maize cultivars was estimated, measuring also leaf photosynthetic rates after foliar P spraying. Plants of cultivar P7948 were found to be wettable from the 4th leaf in acropetal direction, whereas other cultivars were unwettable until the 6th leaf had developed. Minor variations in stomatal number and cuticle composition were recorded, but no differences in foliar P absorption were observed between cultivars. Nevertheless, cultivars showed variation in the improvement of photosynthetic capacity following foliar P application. Phosphorus deficiency resulted in ultrastructural disorganisation of mesophyll cells and chloroplasts, which impaired photosynthetic performance, yet there was no effect on stomatal frequency and leaf wettability. This study provides new insights into the influence of P deficiency and cultivar on leaf surface characteristics, foliar P uptake and its effect on physiological processes. Understanding the relationships between leaf characteristics and P uptake allows a more targeted evaluation of foliar P fertilisation as an application technique and contributes to the understanding of foliar uptake mechanisms.

Assessing the nonlinear association of environmental factors with antibiotic resistance genes (ARGs) in the Yangtze River Mouth, China.

The emergence of antibacterial resistance (ABR) is an urgent and complex public health challenge worldwide. Antibiotic resistant genes (ARGs) are considered as a new pollutant by the WHO because of their wide distribution and emerging prevalence. The role of environmental factors in developing ARGs in bacterial populations is still poorly understood. Therefore, the relationship between environmental factors and bacteria should be explored to combat ABR and propose more tailored solutions in a specific region. Here, we collected and analyzed surface water samples from Yangtze Delta, China during 2021, and assessed the nonlinear association of environmental factors with ARGs through a sigmoid model. A high abundance of ARGs was detected. Amoxicillin, phosphorus (P), chromium (Cr), manganese (Mn), calcium (Ca), and strontium (Sr) were found to be strongly associated with ARGs and identified as potential key contributors to ARG detection. Our findings suggest that the suppression of ARGs may be achieved by decreasing the concentration of phosphorus in surface water. Additionally, Group 2A light metals (e.g., magnesium and calcium) may be candidates for the development of eco-friendly reagents for controlling antibiotic resistance in the future.

Harvesting phosphorus-containing moieties for their antibacterial effects.

Clinically manifested resistance of bacteria to antibiotics has emerged as a global threat to society and there is an urgent need for the development of novel classes of antibacterial agents. Recently, the use of phosphorus in antibacterial agents has been explored in quite an unprecedent manner. In this comprehensive review, we summarize the use of phosphorus-containing moieties (phosphonates, phosphonamidates, phosphonopeptides, phosphates, phosphoramidates, phosphinates, phosphine oxides, and phosphoniums) in compounds with antibacterial effect, including their use as ß-lactamase inhibitors and antibacterial disinfectants. We show that phosphorus-containing moieties can serve as novel pharmacophores, bioisosteres, and prodrugs to modify pharmacodynamic and pharmacokinetic properties. We further discuss the mechanisms of action, biological activities, clinical use and highlight possible future prospects.

Effect of foliar application of phosphorus nanoparticles on the performance and sustainable agriculture of sweet corn.

Traditional phosphorus fertilizers are necessary for plant growth but about 80-90% are lost into the surrounding environment via irrigation, therefore nano-fertilizers have been developed as slow-release fertilizers to achieve sustainable agriculture. This trial investigated the impact of the foliar application of hydroxyapatite nanoparticles (HA-NPs) as a source of nano-phosphorus (P-NPs) on two cultivars of sweet corn (yellow and white) throughout two seasons. The morphology and structure of the prepared HA-NPs were characterized via transmission electron microscopy (TEM) and X-ray diffractometry (XRD). In addition, agro-morphological criteria, chemical contents (i.e., photosynthetic pigments, phenols, indoles, minerals, etc.), and genomic template stability percentage (GTS%) were evaluated in the produced sweet corn. The application of 50 mg/l HA-NPs improved the growth characteristics, yield per hectare, leaf pigments, and chemical content of yellow sweet corn, whereas the application of 100 mg/l of HA-NPs to white sweet corn enhanced the vegetative characteristics, production, photosynthetic pigments, phenols, and indoles. The difference in results may be due to the presence of a +ve unique band with SCoT-4 and SCot-2 primers at 1250 and 470 bp in yellow and white corn treated with 50 and 100 mg/l, respectively. The minimum GTS% was recorded at a concentration of 75 mg/l for both white and yellow corn. The HA-NPs can be applied as a foliar source of P-NPs to achieve agricultural sustainability.

Effect of macronutrients (carbon, nitrogen, and phosphorus) on the growth of Chlamydomonas reinhardtii and nutrient recovery under different trophic conditions.

More stringent discharge standards have led to the development of an alternative nutrient recovery system from wastewater. Microalgae cultivation in wastewater treatment works has presented considerable promise from the perspective of sustainable resource management. Growth kinetics models are useful tools to optimize nutrient recovery from wastewater by algal uptake. Therefore, this research aims to identify the growth kinetics of Chlamydomonas reinhardtii under both heterotrophic and phototrophic conditions with different nutrient concentrations that typify those found in wastewater treatment works. In addition, the effects of macronutrients (C, N, and P) on heterotrophic and phototrophic microalgae growth and nutrient recovery were studied. Greater specific growth rates were achieved under heterotrophic conditions than in phototrophic cultivation. The maximum specific growth rates and nutrient recovery efficiencies were achieved at 5 mg P L-1 under both heterotrophic and phototrophic growth conditions. Nitrate was the preferred form of nitrogen source under heterotrophic conditions, while nitrogen sources did not present any significant influences in the phototrophic cultivation. Specific growth rates reported for both heterotrophic and phototrophic microalgae at lower carbon concentrations (3.10 d-1 and 0.46 d-1, sequentially) were higher than those at higher carbon concentrations (1.95 d-1 and 0.22 d-1, respectively). C. reinhardtii presented an extreme capacity to adapt and grow at all experimental conditions tested in heterotrophic and phototrophic cultivations.

Resilient and sustainable production of peanut (Arachis hypogaea) in phosphorus-limited environment by using exogenous gamma-aminobutyric acid to sustain photosynthesis.

Globally, many low to medium yielding peanut fields have the potential for further yield improvement. Low phosphorus (P) limitation is one of the significant factors curtailing Arachis hypogaea productivity in many regions. In order to demonstrate the effects of gamma-aminobutyric acid (GABA) on peanuts growing under P deficiency, we used a pot-based experiment to examine the effects of exogenous GABA on alleviating P deficiency-induced physiological changes and growth inhibition in peanuts. The key physiological parameters examined were foliar gas exchange, photochemical efficiency, proton motive force, reactive oxygen species (ROS), and adenosine triphosphate (ATP) synthase activity of peanuts under cultivation with low P (LP, 0.5 mM P) and control conditions. During low P, the cyclic electron flow (CEF) maintained the high proton gradient (∆pH) induced by low ATP synthetic activity. Applying GABA during low P conditions stimulated CEF and reduced the concomitant ROS generation and thereby protecting the foliar photosystem II (PSII) from photoinhibition. Specifically, GABA enhanced the rate of electronic transmission of PSII (ETRII) by pausing the photoprotection mechanisms including non-photochemical quenching (NPQ) and ∆pH regulation. Thus, GABA was shown to be effective in restoring peanut growth when encountering P deficiency. Exogenous GABA alleviated two symptoms (increased root-shoot ratio and photoinhibition) of P-deficient peanuts. This is possibly the first report of using exogenous GABA to restore photosynthesis and growth under low P availability. Therefore, foliar applications of GABA could be a simple, safe and effective approach to overcome low yield imposed by limited P resources (low P in soils or P-fertilizers are unavailable) for sustainable peanut cultivation and especially in low to medium yielding fields.

Ecotoxicity of Lead to a Phytoplankton Community: Effects of pH and Phosphorus Addition and Implications for Risk Assessment.

Ecological risk assessment and water quality criteria for lead (Pb) are increasingly making use of bioavailability-based approaches to account for the impact of toxicity-modifying factors, such as pH and dissolved organic carbon. For phytoplankton, which are among the most Pb-sensitive freshwater species, a Pb bioavailability model has previously been developed based on standard single-species exposures at a high phosphorus (P) concentration and pH range of 6.0 to 8.0. It is well known that P can affect metal toxicity to phytoplankton and that the pH of many surface waters can be above 8.0. We aimed to test whether the single-species bioavailability model for Pb could predict the influence of pH on Pb toxicity to a phytoplankton community at both low and high P supply. A 10-species phytoplankton community was exposed to Pb for 28 days at two different pH levels (7.2 and 8.4) and two different P supply levels (low and high, i.e., total P input 10 and 100 µg/L, respectively) in a full factorial 2 × 2 test design. We found that the effects of total Pb on three community-level endpoints (biodiversity, community functioning, and community structure) were highly dependent on both pH and P supply. Consistent lowest-observed-effect concentrations (LOECs) ranged between 21 and >196 µg total Pb/L and between 10 and >69 µg filtered Pb/L. Long-term LOECs were generally higher, that is, 69 µg total Pb/L (42 µg filtered Pb/L) or greater, across all endpoints and conditions, indicating recovery near the end of the exposure period, and suggesting the occurrence of acclimation to Pb and/or functional redundancy. The highest toxicity of Pb for all endpoints was observed in the pH 7.2 × low P treatment, whereas the pH 8.4 × low P and pH 8.4 × high P treatment were the least sensitive treatments. At the pH 7.2 × high P treatment, the algal community showed an intermediate Pb sensitivity. The effect of pH on the toxicity of filtered Pb could not be precisely quantified because for many endpoints no effect was observed at the highest Pb concentration tested. However, the long-term LOECs (filtered Pb) at low P supply suggest a decrease in Pb toxicity of at least 1.6-fold from pH 7.2 to 8.4, whereas the single-species algal bioavailability model predicted a 2.5-fold increase. This finding suggests that bioavailability effects of pH on Pb toxicity cannot be extrapolated as such from the single species to the community level. Overall, our data indicate that, although the single-species algal Pb bioavailability model may not capture pH effects on Pb ecotoxicity in multispecies systems, the bioavailability-based hazardous concentration for 5% of the species was protective of long-term Pb effects on the structure, function, and diversity of a phytoplankton community in a relevant range of pH and P conditions. Environ Toxicol Chem 2023;42:2684-2700. © 2023 SETAC.