Silver nanoparticles affect germination and photosynthesis in tobacco seedlings

Extensive commercialization of silver nanoparticles (AgNPs) raises the risk of their accumulation in the soil-plant system. Once released into the environment, AgNPs are prone to chemical transformations, which make it hard to determine whether their phytotoxic effects are purely NP-related or a consequence of released Ag+ ions. In this study the effects of 25, 50, 75, 100 and 150 μM AgNPs and AgNO3 on seed germination and early growth of tobacco (Nicotiana tabacum L.) seedlings were compared. Additionally, the effects on photosynthetic performance and pigment content were investigated. Germination rate and index values indicated delayed and slower germination in some AgNP treatments. Lower AgNP concentrations stimulated root growth, but induced a prominent reduction in fresh weight. By contrast, all AgNO3 concentrations inhibited root growth but only the higher ones decreased fresh weight. Obtained results imply that the observed AgNP toxicity could be ascribed to NP form and can be correlated with high AgNP stability in the solid medium. On the other hand, the majority of AgNP and AgNO3 treatments induced an increase in chlorophyll content that was accompanied by significantly lower values of relative electron transport rate and coefficient of photochemical quenching, implying an inhibition of the electron transport chain. A similar impact of AgNPs and AgNO3 on photosynthesis can be correlated with lower stability of AgNPs in a liquid medium, resulting in AgNP aggregation and dissolution of Ag+ ions

A polyphasic approach to the study of the genus Nitzschia (Bacillariophyta): three new planktonic species from the Adriatic Sea

The paraphyletic diatom genus Nitzschia comprises over 1000 morphologically distinct pennate taxa, known from the benthos and plankton of freshwater, brackish and marine environments. The principal diagnostic characters for delimitation of Nitzschia species include valve shape, the position and structure of the raphe, presence/absence and shape of the proximal raphe endings and terminal raphe fissures, areola structure, and specific morphometric features such as cell size, and stria and fibula density. In this study, we isolated 12 diatom strains into culture from samples collected at the surface or greater depths of the southeastern Adriatic Sea. Morphological analyses included LM, SEM and TEM observations, which, along with specific morphometric features, allowed us to distinguish three new Nitzschia species. These findings were congruent with the results of phylogenetic analyses performed on nuclear‐encoded SSU (18S) rDNA and chloroplast‐encoded rbcL and psbC genes. One of the new species (Nitzschia dalmatica sp. nov.) formed a lineage within a clade of Bacillariaceae containing members of the Nitzschia sect. Dubiae, which was sister to Psammodictyon. A second lineage was part of a novel clade that is significantly distinct from other Nitzschia species sequenced so far and includes Nitzschia adhaerens sp. nov. and N. cf. adhaerens. A further new species was found, Nitzschia inordinata sp. nov., which appeared as the sister group to the N. adhaerens clade and the conopeoid Nitzschia species in our phylogenetic trees. Our findings contribute to the overall diversity of genus Nitzschia, especially in identifying some deep branches within the Bacillariaceae, and highlight under‐scoring of this genus in marine plankton.info:eu-repo/semantics/acceptedVersio

Multigene phylogeny and morphology of newly isolated strain of Pseudo-nitzschia mannii Amato & Montresor (Adriatic Sea)

An increasing number of cryptic and pseudo-cryptic species have been found within many newly described diatom species. To resolve the phylogenetic relationships of the genus Pseudo-nitzschia, molecular markers are being widely used in combination (or separately) with different morphological characters. Sequence analysis of ribosomal DNA markers (18S, ITS and 28S) and morphological analyses of Pseudo-nitzschia mannii strain (CIM_D-4), isolated from the Telaš´cica Bay (Adriatic Sea), differentiate it from all other currently reported strains of this species

Coating-Dependent Effects of Silver Nanoparticles on Tobacco Seed Germination and Early Growth

Silver nanoparticles, AgNPs, are used in a wide range of consumer products because of their excellent antimicrobial properties. AgNPs released into the environment are prone to transformations such as aggregation, oxidation, or dissolution so they are often stabilised by coatings that a ect their physico-chemical properties and change their e ect on living organisms. In this study we investigated the stability of polyvinylpyrrolidone PVP and cetyltrimethylammonium bromide CTAB coated AgNPs in an exposure medium, as well as their e ect on tobacco germination and early growth. AgNP-CTAB was found to be more stable in the solid Murashige and Skoog MS medium compared to AgNP-PVP. The uptake and accumulation of silver in seedlings was equally effcient after exposure to both types of AgNPs. However, AgNP-PVP induced only mild toxicity on seedlings growth, while AgNP-CTAB caused severe negative e ects on all parameters, even compared to AgNO3. Moreover, CTAB coating itself exerted negative e ects on growth. Cysteine addition generally alleviated AgNP-PVP-induced negative e ects, while it failed to improve germination and growth parameters after exposure to AgNP-CTAB. These results suggest that the toxic e ects of AgNP-PVP are mainly a consequence of release of Ag+ ions, while phytotoxicity of AgNP-CTAB can rather be ascribed to surface coating itself

Synthesis and In Vitro Characterization of Ascorbyl Palmitate-Loaded Solid Lipid Nanoparticles

Antitumor applications of ascorbic acid (AA) and its oxidized form dehydroascorbic acid (DHA) can be quite challenging due to their instability and sensitivity to degradation in aqueous media. To overcome this obstacle, we have synthesized solid lipid nanoparticles loaded with ascorbyl palmitate (SLN-AP) with variations in proportions of the polymer Pluronic F-68. SLNs were synthesized using the hot homogenization method, characterized by measuring the particle size, polydispersity, zeta potential and visualized by TEM. To investigate the cellular uptake of the SLN, we have incorporated coumarin-6 into the same SLN formulation and followed their successful uptake for 48 h. We have tested the cytotoxicity of the SLN formulations and free ascorbate forms, AA and DHA, on HEK 293 and U2OS cell lines by MTT assay. The SLN-AP in both formulations have a cytotoxic effect at lower concentrations when compared to ascorbate applied the form of AA or DHA. Better selectivity for targeting tumor cell line was observed with 3% Pluronic F-68. The antioxidative effect of the SLN-AP was observed as early as 1 h after the treatment with a small dose of ascorbate applied (5 µM). SLN-AP formulation with 3% Pluronic F-68 needs to be further optimized as an ascorbate carrier due to its intrinsic cytotoxicity

Nanoplastic-Induced Nanostructural, Nanomechanical, and Antioxidant Response of Marine Diatom Cylindrotheca closterium

The aim of this study was to examine the effect of positively charged (amine-modified) and negatively charged (carboxyl-modified) polystyrene nanoplastics (PS NPs) on the nanostructural, nanomechanical, and antioxidant responses of the marine diatom Cylindrotheca closterium. The results showed that both types of PS NPs, regardless of surface charge, significantly inhibited the growth of C. closterium during short-term exposure (3 and 4 days). However, longer exposure (14 days) to both PS NPs types did not significantly inhibit growth, which might be related to the detoxifying effect of the microalgal extracellular polymers (EPS) and the higher cell abundance per PS NPs concentration. The exposure of C. closterium to both types of PS NPs at concentrations above the corresponding concentrations that resulted in a 50% reduction of growth (EC50 ) demonstrated phytotoxic effects, mainly due to the excessive production of reactive oxygen species, resulting in increased oxidative damage to lipids and changes to antioxidant enzyme activities. Diatoms exposed to nanoplastics also showed a significant decrease in cell wall rigidity, which could make the cells more vulnerable. Atomic force microscopy images showed that positively charged PS NPs were mainly adsorbed on the cell surface, while both types of PS NPs were incorporated into the EPS that serves to protect the cells. Since microalgal EPS are an important food source for phytoplankton grazers and higher trophic levels, the incorporation of NPs into the EPS and interactions with the cell walls themselves may pose a major threat to marine microalgae and higher trophic levels and, consequently, to the health and stability of the marine ecosystem

Kadmij i cink induciraju slične promjene u uzorku proteina i glikoproteina u klijancima i odraslim biljkama duhana (Nicotiana tabacum L.)

The effects of 10 μmol L-1 and 15 μmol L-1 cadmium (Cd), a nonessential toxic element and 25 μmol L-1 and 50 μmol L-1 zinc (Zn), an essential micronutrient, on proteins and glycoproteins of Nicotiana tabacum L. seedlings and plants were investigated after exposure to each metal alone or to their combinations. Changes in only few polypeptides related to heavy metal treatments were observed in tobacco seedlings and leaves of adult plants, while the greatest change in total soluble protein pattern was observed in plant roots. Differences between control and treated tobacco tissues were more pronounced in the glycoprotein pattern, which was analysed by application of different lectins. The majority of the detected glycoproteins in leaves and roots of adult plants can be considered as a result of enhanced glycosylation due to heavy metal stress. The difference in glycoproteins between Cd and Zn application on tobacco seedlings and adult plants could not be determined since enhanced glycosylation was noticed after treatment with either metal alone or in combination. Therefore, it can be concluded that both metals induced N- and Oglycosylation as a result of changed environmental conditions.Ispitivali smo učinke 10 μmol L-1 i 15 μmol L-1 kadmija (Cd), neesencijalnoga toksičnog elementa i 25 μmol L-1 i 50 μmol L-1 cinka (Zn), esencijalnog mikronutrijenta, na proteine i glikoproteine u klijancima i odraslim biljkama Nicotiana tabacum L. nakon izlaganja svakomu metalu posebno ili njihovim kombinacijama. Promjene kod nekoliko polipeptida koje su uočene u klijancima i listovima odraslih biljaka nisu bile brojne, dok su one najvažnije zabilježene u uzorku ukupnih topljivih proteina u korijenu biljke. Razlike između kontrole i tretiranog tkiva duhana bile su izraženije kod glikoproteina koji su analizirani primjenom različitih lektina. Većina glikoproteina uočenih u listovima i korijenu odraslih biljaka može se smatrati rezultatom povećane glikozilacije zbog stresa koji uzrokuju teški metali. Nije bilo moguće utvrditi razliku u glikoproteinima između tretiranja klijanaca i odraslih biljaka duhana kadmijem i cinkom jer je povećana glikozilacija utvrđena i nakon tretmana svakim metalom posebno i nakon tretmana njihovim kombinacijama. Stoga se može zaključiti da su, kao rezultat promijenjenih uvjeta u okolišu, oba metala potaknula N- i O-glikozilaciju