Interaction of selected herbicides with soil constituents

The behavior of six herbicides in soil was studied under controlled laboratory conditions. Sorption of bromacil, chiorotoluron and diuron was assessed by the batch equilibration procedure over a broad range of aqueous phase sorbate concentration. Linear equilibrium sorption constants (K[subscript p]) were slightly higher at 4° C than at 25° C and many-fold higher in the organic soil than in loamy sand soil. By referencing sorption to soil organic carbon content (OC), this vast variation was reduced to less than 3-fold variation in K[subscript oc]. The isosteric heats of sorption were exothermic and low suggesting an entropy driven mechanism. Water solubilities (S) and octanol-water partition coefficients (K[subscript ow]) of the compounds were determined and used to derive equations for predicting K[subscript oc]. These equations are useful in estimating sorption of related pesticides and pollutants from knowing their K[subscript ow] and S. Degradation of the three herbicides was followed by monitoring [superscript 14]C0₂ evolution from soil. Temperature affected degradation more than did soil type or initial herbicide concentration. The degradation was tripled with a 10° rise in temperature from 25 to 35° C. The presence of herbicides did not affect the activity of soil micro-organisms indicating that degradation was a co-metabolism process. Degradation fit first-order kinetics with no lag phase and with minimum half-lives of about 200 days for diuron and chiorotoluron and 2600 days for bromacil. The binding of these three herbicides plus diquat, glyphosate and simazine with water-soluble soil organic materials (WSSOM) and soil humic acids (HA) was studied by gel filtration chromatography. The chromatographic method adapted by Hummel and Dreyer (1962) was very successful in proving the existence of binding. Noted differences in the elution behavior of herbicides were related to their physical and chemical properties and their Interaction complexes. Infrared (IR) spectroscopy showed the involvement of ion exchange reactions in diquat and H-bonding in diuron, chiorotoluron and bromacil binding with WSSOM and HA. Shifts in some characteristic IR absorption bands suggested the formation of charge transfer complexes in WSSOM and HA interactions with bromacil, chiorotoluron and diuron but not with diquat. The results appear significant in evaluating pesticides and pollutants mobility and transport in soil and water environments

Enhanced immunostimulatory activity of cyclic dinucleotides on mouse cells when complexed with a cell-penetrating peptide or combined with CpG

Recognition of pathogen-derived nucleic acids by immune cells is critical for the activation of protective innate immune responses. Bacterial cyclic dinucleotides (CDNs) are small nucleic acids that are directly recognized by the cytosolic DNA sensor STING (stimulator of IFN genes), initiating a response characterized by proinflammatory cytokine and type I IFN production. Strategies to improve the immune stimulatory activities of CDNs can further their potential for clinical development. Here, we demonstrate that a simple complex of cylic-di-GMP with a cell-penetrating peptide enhances both cellular delivery and biological activity of the cyclic-di-GMP in murine splenocytes. Furthermore, our findings establish that activation of the TLR-dependent and TLR-independent DNA recognition pathways through combined use of CpG oligonucleotide (ODN) and CDN results in synergistic activity, augmenting cytokine production (IFN-α/β, IL-6, TNF-α, IP-10), costimulatory molecule upregulation (MHC class II, CD86), and antigen-specific humoral and cellular immunity. Results presented herein indicate that 3′3′-cGAMP, a recently identified bacterial CDN, is a superior stimulator of IFN genes ligand than cyclic-di-GMP in human PBMCs. Collectively, these findings suggest that the immune-stimulatory properties of CDNs can be augmented through peptide complexation or synergistic use with CpG oligonucleotide and may be of interest for the development of CDN-based immunotherapeutic agents. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Influence of Prior Influenza Vaccination on Antibody and B-Cell Responses

Currently two vaccines, trivalent inactivated influenza vaccine (TIV) and live attenuated influenza vaccine (LAIV), are licensed in the USA. Despite previous studies on immune responses induced by these two vaccines, a comparative study of the influence of prior influenza vaccination on serum antibody and B-cell responses to new LAIV or TIV vaccination has not been reported. During the 2005/6 influenza season, we quantified the serum antibody and B-cell responses to LAIV or TIV in adults with differing influenza vaccination histories in the prior year: LAIV, TIV, or neither. Blood samples were collected on days 0, 7–9 and 21–35 after immunization and used for serum HAI assay and B-cell assays. Total and influenza-specific circulating IgG and IgA antibody secreting cells (ASC) in PBMC were detected by direct ELISPOT assay. Memory B cells were also tested by ELISPOT after polyclonal stimulation of PBMC in vitro. Serum antibody, effector, and memory B-cell responses were greater in TIV recipients than LAIV recipients. Prior year TIV recipients had significantly higher baseline HAI titers, but lower HAI response after vaccination with either TIV or LAIV, and lower IgA ASC response after vaccination with TIV than prior year LAIV or no vaccination recipients. Lower levels of baseline HAI titer were associated with a greater fold-increase of HAI titer and ASC number after vaccination, which also differed by type of vaccine. Our findings suggest that the type of vaccine received in the prior year affects the serum antibody and the B-cell responses to subsequent vaccination. In particular, prior year TIV vaccination is associated with sustained higher HAI titer one year later but lower antibody response to new LAIV or TIV vaccination, and a lower effector B-cell response to new TIV but not LAIV vaccination