Firmenich (United States)

Abstract State transitions balance excitation-energy distribution between Photosystem I and Photosystem II in higher plants. Stn7-mediated phosphorylation of the N-terminus of the light-harvesting complex II protein Lhcb2 plays a central role in photosynthetic state transitions. However, it remains unclear how the intrinsic charge of this region, independent of its phosphorylation status, influences state transitions and thylakoid membrane organization. Here, we introduced specific charge-altering mutations in the Lhcb2 N-terminus of Arabidopsis thaliana in the lhcb2 knock-out background and analyzed their effects on LHCII phosphorylation, state transition dynamics, PSI–LHCII complex formation, and thylakoid ultrastructure. Substitution of a conserved positively charged arginine with a negatively charged glutamate (R2E) markedly reduced Lhcb1 and Lhcb2 phosphorylation and state transition efficiency, and abolished PSI–LHCII complex formation. In contrast, introducing a negative charge at a downstream position (Q9E) had no detectable effects. Electron microscopy revealed no significant changes in thylakoid organization in either mutant compared to WT Lhcb2 plants. Despite strongly reduced Lhcb1 and Lhcb2 phosphorylation in the R2E mutant, residual state transitions persisted, potentially mediated by Stn7-dependent phosphorylation of other target proteins. Together, these results provide insight into the role of N-terminal LHCII electrostatics in state transitions and thylakoid membrane organization in plants.

Abstract Our goal was to evaluate the effect of a phytogenic additive (Digestarom® Prime, dsm-firmenich, Switzerland) on ruminal fermentation of beef cattle grazing tropical pastures during the raining season. Six Nellore young bulls previously fistulated in the rumen were kept in the same paddock (2.2 ha), with B. Brizantha cv. Marandú, equipped with electronic feeders that provided individual access (Intergado® System), from December to March. The experiment was conducted in a 3x3 Latin square design duplicated simultaneously. The treatments consisted of a basal mineral supplement, with the inclusion of Digestarom® in doses adjusted to 0.4 g/animal/day (D04) or 0.6 g/animal/day (D06) or of Monensin (Mon; 15 ppm). Animals were weighed at the beginning of each experimental period to adjust the amount of supplement provided. In each experimental period, 13 days were allowed for adaptation to the treatment and, on the 14th day of each period, ruminal fluid was collected from the animals at 07:00, 12:00, 19:00 and 00:00 hours for subsequent analysis of volatile fatty acids (VFA), ammonia, and microbial protein. The data was analyzed using Proc Glimmix on SAS on Demand, adopting a significance level of 5%. There was an interaction between time and treatment for VFA, acetate, butyrate and propionate (P< 0.05). Overall, the pattern of VFA production was similar for animals on D06 and Mon, with peak of VFA production, acetate, propionate and butyrate at 19:00, while animals receiving D04 presented a peak on VFA production at 00:00. Average total VFA production was 166 mmol/L for Mon, 175 mmol/L for D04 and 167 mmol/L for D06. There was an effect of time of collection on ammonia production (P< 0.05), with all treatments presenting the highest ammonia production at 19:00, but no effect of treatment was observed (P >0.05). Average ammonia production was 39.4 mg/dL for Mon, 48.5 mg/dL for D04 and 48,3 mg/dL for D06. Interaction of time and treatment was also observed for microbial protein (P< 0.05), with average microbial protein production of 327 µg/mL for Mon, 343 for D04 and 317 µg/mL for D06. In conclusion, Digestarom® at dose of 0.6 g/animal/day provides a pattern of ruminal fermentation similar to monensin for grazing beef cattle.

A comprehensive review of existing toxicity and human exposure data for the ultraviolet filter avobenzone (butyl methoxydibenzoylmethane) was conducted to assess its safety as currently used in over-the-counter sunscreen formulations. Avobenzone has a suitable safety profile without any clear markers of toxicity or endpoints of concern. There are sufficient clinical studies and in vitro and in vivo toxicity studies in animal models to assess avobenzone’s pharmacokinetics, pharmacodynamics, and potential toxicological properties, supportive of its long history of safe use. No harmonized dermal absorption value was available, but the clinical data indicate low percutaneous absorption of avobenzone in humans (≤0.59% of the applied dose). There were no data to characterize the distribution of avobenzone; however, four tentative metabolites of avobenzone have been identified, and limited excretion in urine was demonstrated in human biomonitoring studies. Avobenzone generally did not cause dermal irritation or sensitization, but indications of photoallergy have been reported in clinical case studies. The acute toxicity profile indicated that avobenzone has minimal toxicity. The no-observed-adverse-effect level (NOAEL) for general toxicity from a rat dietary subchronic toxicity study was 450 mg/kg/day. There was no evidence of avobenzone effects on immune tissues or the estrogen, androgen, or thyroid systems. Although there were no formal 2-year carcinogenicity studies for avobenzone, a 90-day dietary exposure study in rats did not show any increase in hyperplasia of any tissue or evidence of cytotoxicity, and avobenzone has not shown any indication of genotoxicity either in vitro or in vivo. Together, this indicates that key events for modes of action for avobenzone are absent and carcinogenicity in humans is unlikely. Based on the selected rat subchronic NOAEL and conservative assumptions for estimating the systemic exposure dose (SED) from the application of sunscreen products, margins of exposure (defined as the ratio of NOAEL to SED) greater than 100 were obtained for avobenzone. Therefore, the available data show that avobenzone is unlikely to pose a risk to human health when used in sunscreen products at concentrations up to the permitted maximum usage levels in the United States and Canada, which is 3%.

While progress has been made in recent years, there are still no suitable and accepted in silico, in vitro, or in vivo models that can be used to accurately predict whether a chemical substance has the intrinsic property to cause immune-mediated chemical respiratory allergy, typically manifested as allergic asthma or allergic rhinitis which represents a severe health hazard. Regulatory authorities have relied primarily on clinical evidence (case reports, clinical databases, worker exposure studies) to classify substances as respiratory sensitizers, but this evidence can lack a proven immunological mechanism which is necessary to identify substances which can cause life-long sensitization and clinically relevant allergic symptoms in the respiratory tract in an exposed population (such respiratory allergens may be considered as “true” sensitizers, in analogy to the definition of skin sensitization, and in contrast to respiratory irritants). In light of this, the European Center for Ecotoxicology and Toxicology of Chemicals convened a Task Force to evaluate the types of clinical methods and data sources and the implications of relying on such data for regulatory decision making from a scientific perspective. Recognizing that there are benefits and important insights from using such data, significant shortcomings were identified. With clinical work being focused on treatment and diagnosis of individual patients, the approaches and methods used for clinical guidance, diagnostics and reporting have serious limitations in proving the respiratory sensitization potential of a specific chemical, definitely restricting their suitability in deriving legally binding hazard classifications for human health protection. Even within the current broader regulatory definition of respiratory sensitization, a robust assessment and sound evidence of causation by a specific chemical seems mandatory in order to avoid misclassifications. Application of a systematic weight-of-evidence approach is considered suitable to determine the level of confidence, including a thorough assessment of the specificity or non-specificity of observed bronchial hyperreactivity. Recommendations proposed in this publication may not only aid industry and regulators in their decision making but also facilitate a further exchange between stakeholders to improve the data used to (a) more precisely identify true respiratory sensitizers to effectively protect human health, (b) aid evaluation of potential predictive models, and (c) encourage regulators to clarify guidance and to consider a re-evaluation of the current regulatory definition of respiratory sensitizers.

Abstract Two unknown peaks were sometimes observed during analysis for terpene hydroperoxides (THPs) in various citrus oils using high‐performance liquid chromatography with post‐column luminol‐mediated chemiluminescence detection (HPLC‐CL). These two peaks showed behaviour similar to previously observed peroxyhemiacetals (PHAs) that formed from THPs and aldehydes in citrus oils. Like those PHAs, the unknown peaks also diminished in aqueous solution over time, but instead of liberating THPs, H2O2 was the product of dissociation. Working in tangerine oil, a similar investigation was performed as per our previously reported work on terpene‐derived PHAs, and these two unknown peaks were attributed to PHA adducts of H2O2 with octanal (C8 ald) or decanal (C10 ald), respectively. Each peak consisted of an enantiomeric pair, and the identification of these four compounds was made via HPLC‐CL retention time matching using two separation systems with different selectivity, and NMR analysis. The two enantiomeric adducts from H2O2 and octanal co‐eluted with linalool acetate hydroperoxide (Lin‐Ac‐HP) if it was present in the oil, but they can be distinguished by re‐injecting aged prepared samples. The H2O2‐derived PHAs will slowly dissociate and therefore be decreased by the sample preparation treatment while any Lin‐Ac‐HP that may be present will remain unchanged or increase.

Total internal reflection microscopy (TIRM) is used to directly, sensitively, and simultaneously measure colloidal interactions, dynamics, and deposition for a broad range of polymer-surfactant compositions. A deposition state diagram containing comprehensive information about particle interactions, trajectories, and deposition behavior is obtained for polymer-surfactant compositions covering four decades in both polymer and surfactant concentrations. Bulk polymer-surfactant phase behavior and surface properties are characterized to provide additional information to interpret mechanisms. Materials investigated include cationic acrylamide-acrylamidopropyltrimonium copolymer (AAC), sodium lauryl ether sulfate (SLES) surfactant, silica colloids, and glass microscope slides. Measured colloid-substrate interaction potentials and deposition behavior show nonmonotonic trends vs polymer-surfactant composition and appear to be synergistic in the sense that they are not easily explained as the superposition of single-component-mediated interactions. Broad findings show that at some compositions polymer-surfactant complexes mediate bridging and depletion attractions that promote colloidal deposition, whereas other compositions produce electrosteric repulsion that deters colloidal deposition. These findings illustrate mechanisms underlying colloid-surface interactions in polymer-surfactant mixtures, which are important to controlling selective colloidal deposition in multicomponent formulation applications.

SUMMARYMost natural odors are complex mixtures of many volatile components, competing to bind odorant receptors (ORs) expressed in olfactory sensory neurons (OSNs) of the nose. To date surprisingly little is known about how OR antagonism shapes neuronal representations in the periphery of the olfactory system. Here, we investigated its prevalence, the degree to which it disrupts OR ensemble activity, and its conservation across related ORs. Calcium imaging microscopy of dissociated OSNs revealed significant inhibition, often complete attenuation, of responses to indole, a commonly occurring volatile associated with both floral and fecal odors, by a set of 36 tested odorants. To confirm an OR mechanism for the observed inhibition, we performed single-cell transcriptomics on OSNs that exhibited specific response profiles to a diagnostic panel of odorants and identified the receptor Olfr743 which, when tested in vitro, recapitulated ex vivo responses. We screened ten ORs from the Olfr743 clade with 800 perfumery-related odorants spanning a range of chemical scaffolds and functional groups, over half of which (430) antagonized at least one of the ten ORs. Furthermore, OR activity outcomes were divergent rather than redundant, even for the most closely related paralogs. OR activity fitted a mathematical model of competitive receptor binding and suggests that normalization of OSN ensemble responses to odorant mixtures is the rule rather than the exception. In summary, we observed OR antagonism, inverse agonism and partial agonism occurring frequently and in a combinatorial manner. Thus, extensive receptor-mediated computation of mixture information appears to occur in the olfactory epithelium prior to transmission of odor information to the olfactory bulb.

Photodegradation can be an important abiotic degradation process to consider for the fate and persistence assessment of chemical substances in the environment. In this work, using a fragrance ingredient (FI, (E)-4-(2,2,3,6-tetramethylcyclohexyl)but-3-en-2-one) as an example, we developed a streamlined workflow to investigate direct photodegradation of chemicals in the aquatic environment, including laboratory investigation of kinetics and transformation products and estimation of its aquatic environmental half-lives. Direct photodegradation was determined to be the dominant photodegradation process for FI with a quantum yield of 0.25, which was supported by photodegradation experiments conducted in natural sunlight. Accounting for light attenuation by dissolved organic matter in natural waters of different depths resulted in aquatic half-lives of <31 days even at polar latitudes. Photoisomerization was shown to be a major photodegradation pathway along with the formation and subsequent degradation of constitutional isomers and photooxidation products. These results contributed to FI being assessed as non-persistent in the environment.