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

Proteomika u istraživanjima toksičnosti teških metala u biljaka

Plants endure a variety of abiotic and biotic stresses, all of which cause major limitations to production. Among abiotic stressors, heavy metal contamination represents a global environmental problem endangering humans, animals, and plants. Exposure to heavy metals has been documented to induce changes in the expression of plant proteins. Proteins are macromolecules directly responsible for most biological processes in a living cell, while protein function is directly influenced by posttranslational modifications, which cannot be identified through genome studies. Therefore, it is necessary to conduct proteomic studies, which enable the elucidation of the presence and role of proteins under specific environmental conditions. This review attempts to present current knowledge on proteomic techniques developed with an aim to detect the response of plant to heavy metal stress. Significant contributions to a better understanding of the complex mechanisms of plant acclimation to metal stress are also discussed.Biljke su neprestano izložene različitim čimbenicima abiotičkog i biotičkog stresa koji nepovoljno utječu na njihovu produktivnost. Teški metali kao česti zagađivači okoliša vrlo nepovoljno djeluju na sva živa bića, uključujući biljke, životinje i ljude. Poznato je da teški metali mogu mijenjati ekspresiju biljnih proteina. Proteine ubrajamo u biološki vrlo važne makromolekule čija je aktivnost u stanici izravno ovisna o posttranslacijskim modifikacijama, koje nije moguće pratiti na razini genoma. Stoga je nužno provoditi proteomska istraživanja kako bi se razotkrila prisutnost i uloga proteina u različitim vrstama okolišnog stresa. U ovom radu sažete su različite tehnike i metode istraživanja učinaka teških metala na biljni proteom, uključujući i sažet osvrt na složene mehanizme odgovora biljke na stres izazvan teškim metalima

Proteomika u istraživanjima toksičnosti teških metala u biljaka

Plants endure a variety of abiotic and biotic stresses, all of which cause major limitations to production. Among abiotic stressors, heavy metal contamination represents a global environmental problem endangering humans, animals, and plants. Exposure to heavy metals has been documented to induce changes in the expression of plant proteins. Proteins are macromolecules directly responsible for most biological processes in a living cell, while protein function is directly influenced by posttranslational modifications, which cannot be identified through genome studies. Therefore, it is necessary to conduct proteomic studies, which enable the elucidation of the presence and role of proteins under specific environmental conditions. This review attempts to present current knowledge on proteomic techniques developed with an aim to detect the response of plant to heavy metal stress. Significant contributions to a better understanding of the complex mechanisms of plant acclimation to metal stress are also discussed.Biljke su neprestano izložene različitim čimbenicima abiotičkog i biotičkog stresa koji nepovoljno utječu na njihovu produktivnost. Teški metali kao česti zagađivači okoliša vrlo nepovoljno djeluju na sva živa bića, uključujući biljke, životinje i ljude. Poznato je da teški metali mogu mijenjati ekspresiju biljnih proteina. Proteine ubrajamo u biološki vrlo važne makromolekule čija je aktivnost u stanici izravno ovisna o posttranslacijskim modifikacijama, koje nije moguće pratiti na razini genoma. Stoga je nužno provoditi proteomska istraživanja kako bi se razotkrila prisutnost i uloga proteina u različitim vrstama okolišnog stresa. U ovom radu sažete su različite tehnike i metode istraživanja učinaka teških metala na biljni proteom, uključujući i sažet osvrt na složene mehanizme odgovora biljke na stres izazvan teškim metalima

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

Toksičnost talija u humanoj populaciji

Thallium is a naturally occurring trace element, widely distributed in the earth’s crust, but at very low concentrations. It does not have a known biological use and does not appear to be an essential element for life. It has been considered one of the most toxic heavy metals. Occasionally, there are reports on thallium poisoning as results of suicide or murder attempt or accident. The main threat to humans is through occupational exposure, environmental contamination, and accumulation in food, mainly in vegetables grown on contaminated soil. Increasing use in emerging new technologies and demanding high-tech industry constantly raise concern about exposure risk to all living organisms. Thallium is considered a cumulative poison that can cause adverse health effects and degenerative changes in many organs. The effects are the most severe in the nervous system. The exact mechanism of thallium toxicity still remains unknown, although impaired glutathione metabolism, oxidative stress, and disruption of potassium-regulated homeostasis may play a role. The lack of data about mutagenic, carcinogenic, or teratogenic effects of thallium compounds in humans calls for further research.Talij je u prirodi široko rasprostranjen teški metal, prisutan u vrlo niskim koncentracijama pa ga stoga ubrajamo u elemente u tragovima. Budući da organizmima nije potreban ni u jednoj razvojnoj fazi, ne ubrajamo ga u grupu esencijalnih elemenata. Talij zbog njegovih svojstava ubrajamo među najtoksičnije teške metale. Povremeno se još uvijek pojavljuju slučajevi u kojima je talij upotrijebljen kao sredstvo za pokušaj ubojstva, odnosno samoubojstva, ali i slučajevi nenamjernog, slučajnog trovanja talijem. U današnje vrijeme potencijalna o asnost od trovanja talijem postoji zbog profesionalne izloženosti, izbijanja ekološke katastrofe ili zbog akumulacije u hranidbenim lancima, uglavnom zbog uzgoja hrane na onečišćenom tlu. Sve češća uporaba talija u visokotehnološkoj industriji kao odgovor na zahtjeve moderne tehnologije neprestano povećava rizik od izloženosti svih živih organizama štetnim utjecajima talija u okolišu. Talij ima izuzetno negativan učinak na različite organske sustave, a osobito na živčani sustav. Mehanizmi toksičnosti talija još uvijek nisu u potpunosti razjašnjeni, premda važnu ulogu imaju poremećaji metabolizma glutationa, oksidativni stres i narušavanje homeostaze posredovane ionima kalija. Nedostatak podataka o mutagenim, kancerogenim ili teratogenim učincima talija i njegovih spojeva u ljudi opravdava buduća istraživanja ovog vrlo toksičnog metala