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Herbicides are the extensively used class of pesticides, which beside the active ingredient, in their formulation accompanying substances such as emulsifiers, surfactants and others is needed. The potential toxicity of these synthetic chemicals could pose serious risks to the human health, nontarget organism and environment. In this work we developed biodegradable lignin nanoparticles (LNPs) as environmentally friendly and controlled release carriers of 2,4-dichlorophenoxyacetic acid 2,4-D and 2-methyl-4-chlorophenoxyacetic acid MCPA. LNPs were synthesized via solvent-free nanoprecipitation, achieving high entrapment efficiencies of 90.7% (2,4-D) and 97.4% (MCPA), confirmed by ultraviolet–visible spectroscopy. In vitro release studies revealed sustained herbicide release in buffer solutions (pH 5.5–7.5), with 68–74% release over 72 h, compared to rapid release from commercial formulations. Bioactivity assays of on Descurainia sophia showed that LNP-encapsulated formulation of herbicides reduced weed dry weight by 62.31% and density by 56.09% compared to untreated controls, statistically matching the weed control efficacy of commercial formulations. Field trials further validated these results. LNP-encapsulated 2,4-D + MCPA reduced Amaranthus blitoides dry weight by 91.10% and density by 65.09%, while this new formulation decreased Chenopodium album dry weight and density by 96.01% and by 66.75%, respectively. Notably, lignin’s inherent biodegradability and non-toxic nature provide a sustainable alternative to conventional synthetic adjuvants, significantly reducing the risks of environmental contamination. Our study highlights the potential of lignin-based nanoencapsulation to preserve weed control efficacy while promoting environmentally friendly and safer herbicide formulations.

The highly homologous Cl − channels CLC‐Ka and CLC‐Kb are important for water and salt conservation in the kidney and for the production of endolymph in the inner ear. Mutations in CLC‐Kb lead to Bartter's syndrome and mutations in the small CLC‐K subunit barttin lead to Bartter's syndrome and deafness. Here we show that CLC‐Ka is blocked by the recently identified blocker 2‐( p ‐chlorophenoxy)‐3‐phenylpropionic acid of the rat channel CLC‐K1 with an apparent K D ∼80 μM. We also found that DIDS (4,4′‐diisothiocyanatostilbene‐2,2′‐disulphonic acid), a generic Cl − channel blocker, inhibits CLC‐Ka ( K D ∼90 μM). Surprisingly, the highly homologous channel CLC‐Kb is fivefold to sixfold less sensitive to both compounds. Guided by the crystal structure of bacterial CLC proteins, we identify two amino acids, N68/D68 and G72/E72, in CLC‐Ka and CLC‐Kb, respectively, that are responsible for the differential drug sensitivity. Both residues expose their side chains in the extracellular pore mouth, delineating the probable drug binding site. These novel CLC‐K channel blockers are promising lead compounds for the development of new diuretic drugs.

Pesticide residues and their transformation products are frequently found in groundwater and surface waters. This study examined whether adding pesticide-degrading microorganisms simultaneously with the pesticide at application could significantly reduce diffuse contamination from pesticide use. Degradation of the phenoxyacetic acid herbicides MCPA (4-chloro-2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid) was studied in soil microcosm experiments after simultaneous spraying of herbicide and herbicide-degrading bacteria on an agricultural soil and on a sand with low degradation potential. The latter represented pesticide use on non-agricultural soils poor in microbial activity. Degradation and possible loss of herbicidal effect were also tested in a system with plants and the amounts of bacteria needed to give satisfactory MCPA-degradation rate and the survival of degrading bacteria in formulated MCPA were determined. The results showed >80-99% degradation of 2,4-D and MCPA in soil within 1 day and >99% within 3 days after inoculation with 10⁵-10⁷ herbicide-degrading bacteria g⁻¹ dry weight of soil. Enhanced degradation of MCPA was also obtained in the presence of winter wheat and white mustard without loss of the intended herbicidal effect on white mustard. The survival of an isolated MCPA-degrading Sphingomonas sp. in three realistic concentrations of formulated MCPA was very poor, showing that in practical applications direct contact between the microorganisms and the pesticide formulation must be precluded. The applicability and economic feasibility of the method and the information needed to obtain a useable product for field use are discussed.

Natural fluctuations in soil microbial communities are poorly documented because of the inherent difficulty to perform a simultaneous analysis of the relative abundances of multiple populations over a long time period. Yet, it is important to understand the magnitudes of community composition variability as a function of natural influences (e.g., temperature, plant growth, or rainfall) because this forms the reference or baseline against which external disturbances (e.g., anthropogenic emissions) can be judged. Second, definition of baseline fluctuations in complex microbial communities may help to understand at which point the systems become unbalanced and cannot return to their original composition. In this paper, we examined the seasonal fluctuations in the bacterial community of an agricultural soil used for regular plant crop production by using terminal restriction fragment length polymorphism profiling (T-RFLP) of the amplified 16S ribosomal ribonucleic acid (rRNA) gene diversity. Cluster and statistical analysis of T-RFLP data showed that soil bacterial communities fluctuated very little during the seasons (similarity indices between 0.835 and 0.997) with insignificant variations in 16S rRNA gene richness and diversity indices. Despite overall insignificant fluctuations, between 8 and 30% of all terminal restriction fragments changed their relative intensity in a significant manner among consecutive time samples. To determine the magnitude of community variations induced by external factors, soil samples were subjected to either inoculation with a pure bacterial culture, addition of the herbicide mecoprop, or addition of nutrients. All treatments resulted in statistically measurable changes of T-RFLP profiles of the communities. Addition of nutrients or bacteria plus mecoprop resulted in bacteria composition, which did not return to the original profile within 14 days. We propose that at less than 70% similarity in T-RFLP, the bacterial communities risk to drift apart to inherently different states.

The 2‐(p‐chlorophenoxy)propionic acid (CPP) modulates in a stereoselective manner the macroscopic chloride conductance (gCl), the electrical parameter sustained by the CLC‐1 channel, of skeletal muscle. In order to determine the structural requirements for modulating native gCl and to identify high‐affinity ligands, the effects of newly synthesised CPP analogues have been evaluated on gCl of rat EDL muscle fibres by means of the two‐microelectrode current‐clamp technique. Each type of the following independent modification of CPP structure led to a three‐ to 10‐fold decrease or to a complete lack of gCl‐blocking activity: replacement of the electron‐attractive chlorine atom of the aromatic ring, substitution of the oxygen atom of the phenoxy group, modification at the chiral centre and substitution of the carboxylic function with a phosphonate one. The analogues bearing a second chlorophenoxy group on the asymmetric carbon atom showed a significant gCl‐blocking activity. Similar to racemate CPP, the analogue with this group, spaced by an alkyl chain formed by three methylenic groups, blocked gCl by 45% at 100 μM. These latter derivatives were tested on heterelogously expressed CLC‐1 performing inside‐out patch‐clamp recordings to further define how interaction between drug and channel protein could take place. Depending on the exact chemical nature of modification, these derivatives strongly blocked CLC‐1 with KD values at −140 mV ranging from about 4 to 180 μM. In conclusion, we identified four molecular determinants pivotal for the interaction with the binding site on muscle CLC‐1 channels: (a) the carboxylic group that confers the optimal acidity and the negative charge; (b) the chlorophenoxy moiety that might interact with a hydrophobic pocket; (c) the chiral centre that allows the proper spatial disposition of the molecule; (d) an additional phenoxy group that remarkably stabilises the binding by interacting with a second hydrophobic pocket. British Journal of Pharmacology (2003) 139, 1255–1264. doi:10.1038/sj.bjp.0705364

OBJECTIVES: To evaluate short term immunological changes after agricultural exposure to commercial formulations of chlorophenoxy herbicides. METHODS: Blood samples were collected from 10 farmers within seven days before exposure, one to 12 days after exposure, and again 50 to 70 days after exposure. Whole blood was used to count lymphocyte subsets with monoclonal antibodies. Peripheral blood mononuclear (PBM) cells were used to measure natural killer (NK) cell activity and lymphocyte response to mitogenic stimulations. Values before exposure were used as reference. RESULTS: In comparison with concentrations before exposure, a significant reduction was found one to 12 days after exposure in the following variables (P < 0.05): circulating helper (CD4) and suppressor T cells (CD8), CD8 dim, cytotoxic T lymphocytes (CTL), natural killer cells (NK), and CD8 cells expressing the surface antigens HLA-DR (CD8-DR), and lymphoproliferative response to mitogen stimulations. All immunological values found 50-70 days after exposure were comparable with concentrations before exposure, but mitogenic proliferative responses of lymphocytes were still significantly decreased. CONCLUSIONS: According to our data agricultural exposure to commercial 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA) formulations may exert short term immunosuppressive effects. Further studies should clarify whether the immunological changes found may have health implications and can specifically contribute to cancer aetiology.

Herbicides are widely used to control weeds in agriculture filed, however, the excessive use of the conventional formulation causes harmful side effects on the environment. To relieve this problem, natural polymer nanoparticles as herbicide carrier were rapidly developed and applied in recent years. In the present study, chitosan/tripolyphosphate (CS/TPP) nanoparticles were synthesized as nanocarrier to load herbicide 4-chloro-2-methylphenoxyacetate sodium salt (MCPA-Na). The encapsulation efficiency (EE) of 51.32% was obtained through measuring indirectly by high performance liquid chromatography (HPLC). The free and MCPA-Na-loaded CS/TPP nanoparticles were characterized by using dynamic light scattering (DLS), zeta potential, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The encapsulation of MCPA-Na in CS/TPP nanoparticles resulted in the change of MCPA-Na release profile in different pH media and displayed effective sustained-release under neutral condition. The evaluation of herbicidal activity against Bidens pilosa L. showed that the efficacy enhancement of MCPA-Na was realized after encapsulation in CS/TPP nanoparticles. The proposed herbicide nanoformulation presented a good potential as a sustainable alternative for weed control in agriculture.

Recently, there has been growing concern over the potential impact of CO 2 concentration and temperature on herbicide efficacy. The aim of the study was to examine the influence of single elevated CO 2 (400 vs. 800 ppm) and elevated CO 2 in combination with temperature (21 °C vs. 25 °C) on the effects of auxin herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) (0.5–2 × field recommended rate) to wild mustard ( Sinapis arvensis L.) grown in mixed-culture with spring barley ( Hordeum vulgare L.). MCPA had a detrimental effect on aboveground and belowground biomass, content of chlorophylls, enzymatic and non-enzymatic antioxidants and induced oxidative stress. The significant decline in photosynthetic rate, stomatal conductance and transpiration with MCPA dose was detected. Elevated CO 2 reinforced MCPA efficacy on S. arvensis : sharper decline in biomass, photosynthetic rate and antioxidant enzymes and more pronounced lipid peroxidation were detected. Under elevated CO 2 and temperature, MCPA efficacy to control S. arvensis dropped due to herbicide dilution because of increased root:shoot ratio, higher activity of antioxidants and less pronounced oxidative damage. Reinforced MCPA impact on weeds under elevated CO 2 resulted in higher H. vulgare biomass, while decreased MCPA efficacy under elevated CO 2 and temperature reduced H. vulgare biomass.

Ralstonia eutropha JMP134 possesses two sets of similar genes for degradation of chloroaromatic compounds, tfdCDEFB (in short: tfdI cluster) and tfdDII CII EII FII BII (tfdII cluster). The significance of two sets of tfd genes for the organism has long been elusive. Here, each of the tfd genes in the two clusters on the original plasmid pJP4 was replaced by double recombination with a gene fragment in which a kanamycin resistance gene was inserted into the respective tfd gene's reading frame. The insertion mutants were all tested for growth on 2,4-dichlorophenoxyacetic acid (2,4-D), 2-methyl-4-chlorophenoxyacetic acid (MCPA), and 3-chlorobenzoate (3-CBA). None of the tfdDII CII EII FII BII genes appeared to be essential for growth on 2,4-D or on 3-CBA. Mutations in tfdC, tfdD and tfdF also did not abolish but only retarded growth on 2,4-D, indicating that they were redundant to some extent as well. Of all tfd genes tested, only tfdE and tfdB were absolutely essential, and interruption of those two reading frames abolished growth on 2,4-D, 3-CBA ( tfdE only), and MCPA completely. Interestingly, strains with insertion mutations in the tfdI cluster and those in tfdDII, tfdCII, tfdEII and tfdBII were severely effected in their growth on MCPA, compared to the wild-type. This indicated that not only the tfdI cluster but also the tfdII cluster has an essential function for R. eutropha during growth on MCPA. In contrast, insertion mutation of tfdDII resulted in better growth of R. eutropha JMP134 on 3-CBA, which is most likely due to the prevention of toxic metabolite production in the absence of TfdDII activity.