Accumulation characteristics and fate modeling of phthalic acid esters in surface water from the Three Gorges Reservoir area, China.

Phthalic acid esters (PAEs) are a group of compounds widespread in the environment. To investigate the occurrence and accumulation characteristics of PAEs, surface water samples were collected from the Three Gorges Reservoir area, China. The total concentrations of 11 analyzed PAEs (∑11PAEs) in the collected water samples ranging from 197.7 to 1,409.3 ng/L (mean ± IQR: 583.1 ± 308.4 ng/L). While DEHP was the most frequently detected PAE, DnBP and DnNP were the most predominant PAEs in the analyzed water samples with a mean contribution of 63.3% of the ∑11PAEs. The concentrations of the ∑11PAEs in the water samples from the upper reaches of the Yangtze River were significantly higher than those from the middle reaches. To better understand the transport and fate of the PAEs, seven detected PAEs were modeled by Quantitative Water Air Sediment Interaction (QWASI). The simulated and measured values were close for most PAEs, and differences are within one order of magnitude even for the worst one. For all simulated PAEs, water and particle inflow were main sources in the reservoir, whereas water outflow and degradation in water were important removal pathways. The contribution ratios of different sources/losses varied from PAEs, depending on their properties. The calculated risk quotients of DnNP in the Three Gorges Reservoir area whether based on monitoring or simulating results were all far exceeded the safety threshold value, implying the occurrence of this PAE compound may cause potential adverse effects for the aquatic ecology of the Three Gorges Reservoir area.

Modelling pesticide concentrations in Japanese paddy fields using the RICEWQ model.

Increasing concerns about plant protection products in surface waters have highlighted the importance of pesticide monitoring and modelling, both nowadays integral components of the pesticide registration process. The Rice Water Quality (RICEWQ) model predicts the fate and transport of pesticides under various paddy environmental conditions. The model has been used widely for regulatory purpose in the U.S., while its use in Europe has been limited to regulatory submissions, despite multiple recommendations to adopt RICEWQ as a high tier assessment model for regulatory purposes. The applicability of the RICEWQ model under Japanese agricultural conditions remains unexplored. This study leverages field experimental data to evaluate the RICEWQ model's capability to simulate daily concentrations of two herbicides, mefenacet and pretilachlor, in paddy water and paddy soil in Japan. The RICEWQ model provided a reasonable level of performance for predicting the fate and transport of the two herbicides by ensuring that the simulated daily water balance corresponded with field observations and with minor pesticide-specific calibration. To further improve the performance of the simulations, we implemented a straightforward calibration framework. Calibrating the RICEWQ model improved the accuracy of all simulations; for both herbicides and in both paddy water and paddy soil compartments, the lowest Nash-Sutcliffe efficiency achieved was 0.725, demonstrating excellent performance. However, the RICEWQ model consistently underestimated the peak concentrations of herbicides in paddy water within the first three days of simulation. Simulation results suggested that approximately 50 % of the total applied herbicide was lost from the paddy system. Increasing the duration of the water holding period after pesticide application or increasing the storage capacity of the rice field via excess water storage depth management has the potential to reduce greatly herbicide loss to below 10 % of the total applied herbicide.

Stem cell-specific ecdysone signaling regulates the development of dorsal fan-shaped body neurons and sleep homeostasis.

Complex behaviors arise from neural circuits that assemble from diverse cell types. Sleep is a conserved behavior essential for survival, yet little is known about how the nervous system generates neuron types of a sleep-wake circuit. Here, we focus on the specification of Drosophila 23E10-labeled dorsal fan-shaped body (dFB) long-field tangential input neurons that project to the dorsal layers of the fan-shaped body neuropil in the central complex. We use lineage analysis and genetic birth dating to identify two bilateral type II neural stem cells (NSCs) that generate 23E10 dFB neurons. We show that adult 23E10 dFB neurons express ecdysone-induced protein 93 (E93) and that loss of ecdysone signaling or E93 in type II NSCs results in their misspecification. Finally, we show that E93 knockdown in type II NSCs impairs adult sleep behavior. Our results provide insight into how extrinsic hormonal signaling acts on NSCs to generate the neuronal diversity required for adult sleep behavior. These findings suggest that some adult sleep disorders might derive from defects in stem cell-specific temporal neurodevelopmental programs.

Cellular and molecular mechanisms of asymmetric stem cell division in tissue homeostasis.

The asymmetric cell division determines cell diversity and distinct sibling cell fates by mechanisms linked to mitosis. Many adult stem cells divide asymmetrically to balance self-renewal and differentiation. The process of asymmetric cell division involves an axis of polarity and, second, the localization of cell fate determinants at the cell poles. Asymmetric division of stem cells is achieved by intrinsic and extrinsic fate determinants such as signaling molecules, epigenetics factors, molecules regulating gene expression, and polarized organelles. At least some stem cells perform asymmetric and symmetric cell divisions during development. Asymmetric division ensures that the number of stem cells remains constant throughout life. The asymmetric division of stem cells plays an important role in biological events such as embryogenesis, tissue regeneration and carcinogenesis. This review summarizes recent advances in the regulation of asymmetric stem cell division in model organisms.

Modeling the fate and transport of E. coli pathogens in the Tano River Basin of Ghana under climate change and socioeconomic scenarios.

Surface water contamination by fecal matter threatens human health due to human and biological processes within a watershed, making socioeconomic development crucial for predicting and improving microbiological water quality. Consequently, climate change alters climatic parameters that affect flow regimes and the movement and fate of microorganisms. This study assessed the fate and transport of microbial Escherichia coli (E. coli) concentrations and their sources in the Tano River Basin in Ghana. Additionally, the study predicted future E. coli concentrations using climate change scenarios from the Intergovernmental Panel on Climate Change (IPCC)'s most recent representative concentration pathways (RCPs) and shared socioeconomic pathways (SSPs). Scenario_1 featured planned urbanization, enhanced manure and wastewater treatment, moderate population, livestock density growth, and climate change. Scenario_2 involved higher population growth, minimal improvements in wastewater management, zero manure treatment, higher livestock population, urbanization, and substantial climate change. Calibration and validation using E. coli data from June 2022 to April 2023 showed good agreement with observed concentrations (R2, 0.75 and 0.89; NSE, 0.69 and 0.68; PBIAS, 3.4 and 1.9, respectively). The measured and modeled E. coli concentrations were high, with the highest recording at 2.39 log cfu/100 ml during the rainy season. The study finds that the main causes of E. coli concentrations (44%) are point sources, primarily from human feces and livestock manure, followed by upstream pollution (34%) and non-point sources (22%). Non-point sources became the predominant contributors during periods of maximum discharge due to runoff from land and the dilution of point sources. Again Scenario_1 E. coli dropped to 68% and 97% of reference point levels by the 2050s and 2100s, respectively. E. coli concentrations decrease even more with subsequent treatment, such as tertiary treatment, manure treatment, or both. The scenario analysis demonstrates the potential for E. coli reduction through wastewater and manure treatment, driven by socioeconomic and climate change scenarios.

Decision trees for determining the fate of laboratory animals.

Facilities involved in laboratory animal research often face ethical challenges such as: what should I do with the animals that are no longer suitable for experimental purposes? One of the common answers to this question is to kill them. And while numerous scientifically justifiable reasons exist for killing laboratory animals, we must not overlook our ethical responsibility towards these sentient beings. Animal facility managers and scientists frequently find themselves in a moral dilemma, torn between furthering their research and addressing the well-being of experimental animals required for their studies. We elaborated a concept consisting of six decision trees and recommendations for making informed decisions about the need to kill laboratory animals in research facilities, considering legal and ethical considerations. The concept is based on the German regulatory perspective. However, the measures and decisions for animal welfare can be implemented in all laboratory animal facilities. These recommendations suggest several courses of action, including implementing consistent breeding plans, exploring alternative uses, reassigning surplus animals and their organs, and establishing appropriate housing capacity limits that ensure species-appropriate care. We encourage scientists and animal facility managers to develop and implement decision-making frameworks and procedures tailored to their specific facilities, in the hope that this work will promote a thoughtful and responsible approach to the complex challenges associated with the killing of laboratory animals, advancing scientific progress and the humane treatment of these animals.

Hepatocyte differentiation requires anisotropic expansion of bile canaliculi.

During liver development, bipotential progenitor cells called hepatoblasts differentiate into hepatocytes or cholangiocytes. Hepatocyte differentiation is uniquely associated with multi-axial polarity, enabling the anisotropic expansion of apical lumina between adjacent cells and formation of a three-dimensional network of bile canaliculi (BC). Cholangiocytes, the cells forming the bile ducts, exhibit the vectorial polarity characteristic of epithelial cells. Whether cell polarization feeds back on the gene regulatory pathways governing hepatoblast differentiation is unknown. Here, we used primary hepatoblasts to investigate the contribution of anisotropic apical expansion to hepatocyte differentiation. Silencing of the small GTPase Rab35 caused isotropic lumen expansion and formation of multicellular cysts with the vectorial polarity of cholangiocytes. Gene expression profiling revealed that these cells express reduced levels of hepatocyte markers and upregulate genes associated with cholangiocyte identity. Time-course RNA sequencing demonstrated that loss of lumen anisotropy precedes these transcriptional changes. Independent alterations in apical lumen morphology induced either by modulation of the subapical actomyosin cortex or increased intraluminal pressure caused similar transcriptional changes. These findings suggest that cell polarity and lumen morphogenesis feedback to hepatoblast-to-hepatocyte differentiation.

You can bring plankton to fecal indicator organisms, but you cannot make the plankton graze: particle contribution to E. coli and MS2 inactivation in surface waters.

Organisms that are associated with feces ("fecal indicator organisms") are monitored to assess the potential for fecal contamination of surface water bodies in the United States. However, the effect of the complex mixtures of chemicals and the natural microbial community within surface water ("particles") on fecal indicator organism persistence is not well characterized. We aimed to better understand how particles, including biological (e.g., potential grazers) and inert (e.g., minerals) types, affect the fecal indicator organisms Escherichia coli K-12 ("E. coli") and bacteriophage MS2 in surface waters. A gradient of particles captured by a 0.2-µm-pore-size filter ("large particles") was generated, and the additional particles and dissolved constituents that passed through the filter were deemed "small particles." We measured the ratio of MS2 and E. coli that survived over a 24-h incubation period for each condition (0%-1,000% large-particle concentration in raw water) and completed a linear regression that included large- and small-particle coefficients. Particles were characterized by quantifying plankton, total bacterial cells, and total solids. E. coli and MS2 persistence was not significantly affected by large particles, but small particles had an effect in most waters. Small particles in higher-salinity waters had the largest, negative effect on E. coli and MS2 survival ratios: Significant small-particle coefficients ranged from -1.7 to -5.5 day-1 in the marine waters and -0.89 to -3.2 day-1 in the fresh and estuarine waters. This work will inform remediation efforts for impaired surface water bodies.IMPORTANCEMany surface water bodies in the United States have organisms associated with fecal contamination that exceed regulatory standards and prevent safe recreation. The process to remediate impaired water bodies is complicated because these fecal indicator organisms are affected by the local environmental conditions. For example, the effect of particles in surface water on fecal indicator concentrations are difficult to quantify in a way that is comparable between studies and water bodies. We applied a method that overcomes this limitation to assess the effects of large particles, including natural plankton that could consume the seeded fecal indicator organisms. Even in environmental water samples with diverse communities of plankton present, no effect of large particles on fecal indicator concentrations was observed. These findings have implications for the interpretation and design of future studies, including that particle characterization of surface water may be necessary to assess the fate of fecal indicators.

Chronic bisphenol A induced neurotoxicity: Exposure risk, molecular fate within carp and its potential phytoremediation.

Bisphenol A (BPA) is an endocrine-disrupting toxicant commonly used in the plastics industry, as a result, it is present in large quantities in the environment. Therefore, current study was designed to assess BPA induced neurotoxicity and molecular fate within common carp (Cyprinus carpio), largely used edible fish. Following 6 weeks exposure to BPA 1/5th of 96 h LC50 (1.31 mg/L), brain exhibited oxidative damage, which was evidenced by compromised antioxidant system (CAT, SOD, GSH) and increased level of biomacromolecule peroxidation (MDA and 8-OHDG). Functional damage to the brain observed in the form of blood-brain barrier disruption (decreased tight junction gene expression) and nerve conduction impairment (reduced acetylcholinesterase activity). Mechanistically, apoptotic cell death indicated by characteristic alteration in key biomarkers (bcl-2, caspase, and p53-related gene family). Whereas, coadministration of powdered PP (pomegranate peel) (8 %) with BPA effectively mitigated the BPA toxicity, as evidenced by the restoration of the above-mentioned bioindicators. Thereby, BPA-induced neurotoxicity could be potentially detoxified by applying PP dietary enrichment.

Existence and fate of microplastics in terrestrial environment: A global fretfulness and abatement strategies.

Widespread use of plastics in consumer products, packaging, cosmetics, and industrial and agricultural production has resulted in the ubiquitous occurrence of microplastics in terrestrial environment. Compared to the marine environment, only limited studies have investigated the microplastics pollution and associated risk in terrestrial environment. The present review summarizes the global distribution of microplastics in terrestrial environment, their transport pathways and fate, risk to ecosystem and human health, and abatement strategies. Small particle sizes (<500 µm); fragment, fiber, and film shapes; transparent and white color; polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) polymers were the major characteristics of the microplastics found in terrestrial environment. Microplastics in soils negatively affect soil organisms, while the impact of microplastics in terrestrial environment on human health is poorly understood, which needs to be explored further as there is clear evidence on their presence in human bodies. The removal of microplastics from soil environment is quite complex and costly, thus prevention of their releases is preferable. Among the existing abatement options, biodegradation, which harnesses bacterial strains to degrade microplastics through enzymatic hydrolysis, hold promise for terrestrial environment. Strengthening global cooperation, implementing timely policies on plastic use and recycle, and developing new technologies for control of microplastics are recommended to reduce the pollution in terrestrial environment. Global effort on reducing plastic wastes and enhancing their management is imperative, while substitution with biodegradable plastics could help minimize future accumulation of microplastics in terrestrial environment.

Occurrence and environmental fate of anti-influenza drugs in a subcatchment of the Yodo River Basin, Japan.

Understanding the current situation and risk of environmental contamination by anti-influenza drugs in aquatic environments is key to prevent the unexpected emergence and spread of drug-resistant viruses. However, few reports have been focused on newer drugs that have recently been introduced in clinical settings. In this study, the behaviour of the prodrug baloxavir marboxil (BALM)-the active ingredient of Xofluza, an increasingly popular anti-influenza drug-and its pharmacologically active metabolite baloxavir (BAL) in the aquatic environment was evaluated. Additionally, their presence in urban rivers and a wastewater treatment plant (WWTP) in the Yodo River basin was investigated and compared with those of the major anti-influenza drugs used to date (favipiravir (FAV), peramivir (PER), laninamivir (LAN), and its active metabolite, laninamivir octanoate (LANO), oseltamivir (OSE), and its active metabolite, oseltamivir carboxylate (OSEC), and zanamivir (ZAN)) to comprehensively assess their environmental fate in the aquatic environment. The results clearly showed that BALM, FAV, and BAL were rapidly degraded through photolysis (2-h, 0.6-h, and 0.4-h half-lives, respectively), followed by LAN, which was gradually biodegraded (7-h half-life). In addition, BALM and BAL decreased by up to 47 % after 4 days and 34 % after 2 days of biodegradation in river water. However, the remaining conventional drugs, except for LANO (<1 % after 10 days), were persistent, being transported from the upstream to downstream sites. The LogKd values for the rates of sorption of BALM (0.5-1.6) and BAL (1.8-3.1) on river sediment were higher than those of conventional drugs (-0.5 to 1.7). Notably, all anti-influenza drugs were effectively removed by ozonation (>90-99.9 % removal) after biological treatment at a WWTP. Thus, these findings suggest the importance of introducing ozonation to reduce pollution loads in rivers and the environmental risks associated with drug-resistant viruses in aquatic environments, thereby promoting safe river environments.

The unique distribution pattern of PFAS in landfill organics.

PFAS from degrading landfill waste partition into organic matter, leachate, and landfill gas. Driven by the limited understanding of PFAS distribution in landfill organics, we analyzed PFAS across various depths and seven spatially distinct locations within a municipal landfill. The measured PFAS concentrations in organics ranged from 6.71 to 73.06 µg kg-1, a sum of twenty-nine PFAS from six classes. Perfluorocarboxylic acids (PFCAs) and fluorotelomer carboxylic acids (FTCAs) were the dominant classes, constituting 25-82 % and 8-40 % of total PFAS at different depths. PFBA was the most dominant PFCA with a concentration range of 0.90-37.91 µg kg-1, while 5:3 FTCA was the most prevalent FTCA with a concentration of 0.26-17.99 µg kg-1. A clear vertical distribution of PFAS was observed, with significantly greater PFAS concentrations at the middle depths (20-35 ft), compared to the shallow (10-20 ft) and high depths (35-50 ft). A strong positive correlation (r > 0.50) was noted between total PFAS, total carbon, and dissolved organic matter in landfill organics. Multivariate statistical analysis inferred common sources and transformations of PFAS within the landfill. This study underscores the importance of a system-level analysis of PFAS fate in landfills, considering waste variability, chemical properties, release mechanisms, and PFAS transformations.

Chromatin remodeling in tissue stem cell fate determination.

Tissue stem cells (TSCs), which reside in specialized tissues, constitute the major cell sources for tissue homeostasis and regeneration, and the contribution of transcriptional or epigenetic regulation of distinct biological processes in TSCs has been discussed in the past few decades. Meanwhile, ATP-dependent chromatin remodelers use the energy from ATP hydrolysis to remodel nucleosomes, thereby affecting chromatin dynamics and the regulation of gene expression programs in each cell type. However, the role of chromatin remodelers in tissue stem cell fate determination is less well understood. In this review, we systematically discuss recent advances in epigenetic control by chromatin remodelers of hematopoietic stem cells, intestinal epithelial stem cells, neural stem cells, and skin stem cells in their fate determination and highlight the importance of their essential role in tissue homeostasis, development, and regeneration. Moreover, the exploration of the molecular and cellular mechanisms of TSCs is crucial for advancing our understanding of tissue maintenance and for the discovery of novel therapeutic targets.

Manipulating cell fate through reprogramming: approaches and applications.

Cellular plasticity progressively declines with development and differentiation, yet these processes can be experimentally reversed by reprogramming somatic cells to induced pluripotent stem cells (iPSCs) using defined transcription factors. Advances in reprogramming technology over the past 15 years have enabled researchers to study diseases with patient-specific iPSCs, gain fundamental insights into how cell identity is maintained, recapitulate early stages of embryogenesis using various embryo models, and reverse aspects of aging in cultured cells and animals. Here, we review and compare currently available reprogramming approaches, including transcription factor-based methods and small molecule-based approaches, to derive pluripotent cells characteristic of early embryos. Additionally, we discuss our current understanding of mechanisms that resist reprogramming and their role in cell identity maintenance. Finally, we review recent efforts to rejuvenate cells and tissues with reprogramming factors, as well as the application of iPSCs in deriving novel embryo models to study pre-implantation development.

USP11 deubiquitinates E-cadherin and maintains the luminal fate of mammary tumor cells to suppress breast cancer.

Basal-like breast cancer may originate from luminal epithelial or cancerous cells. Inadequately repaired DNA damage impairs luminal differentiation and promotes aberrant luminal to basal trans-differentiation in mammary epithelial cells (MECs). Ubiquitin-specific peptidase 11 (USP11), a deubiquitinase, plays a critical role in DNA damage repair. The role of USP11 in controlling mammary cell differentiation and tumorigenesis remains poorly understood. We generated Usp11 knockout mice and breast cancer cell lines expressing wild-type (WT) and mutant forms of USP11. By using these mutant mice, cell lines, and human USP11-deficient and -proficient breast cancer tissues, we tested how USP11 controls mammary cell fate. We generated Usp11 knock-out mice and found that deletion of Usp11 reduced the expression of E-cadherin and promoted DNA damage in MECs. Overexpression of WT USP11, but not a deubiquitinase-inactive mutant form of USP11, promoted luminal differentiation, enhanced DNA damage repair, and suppressed tumorigenesis in mice. Mechanistically, we found that USP11 enhanced the protein expression of E-cadherin dependent on its deubiquitinase activity and that USP11 deubiquitinated E-cadherin at K738. We discovered that USP11 is bound to E-cadherin through its C-terminal region. In human breast cancers, expression of USP11 was positively correlated with that of E-cadherin, and high USP11 predicted better recurrence-free survival. Our findings provide compelling genetic and biochemical evidence that USP11 not only promotes DNA damage repair but also deubiquitinates E-cadherin and maintains the luminal feature of mammary tumor cells, thereby suppressing luminal breast cancer.

EnhancerNet: a predictive model of cell identity dynamics through enhancer selection.

Understanding how cell identity is encoded by the genome and acquired during differentiation is a central challenge in cell biology. I have developed a theoretical framework called EnhancerNet, which models the regulation of cell identity through the lens of transcription factor-enhancer interactions. I demonstrate that autoregulation in these interactions imposes a constraint on the model, resulting in simplified dynamics that can be parameterized from observed cell identities. Despite its simplicity, EnhancerNet recapitulates a broad range of experimental observations on cell identity dynamics, including enhancer selection, cell fate induction, hierarchical differentiation through multipotent progenitor states and direct reprogramming by transcription factor overexpression. The model makes specific quantitative predictions, reproducing known reprogramming recipes and the complex haematopoietic differentiation hierarchy without fitting unobserved parameters. EnhancerNet provides insights into how new cell types could evolve and highlights the functional importance of distal regulatory elements with dynamic chromatin in multicellular evolution.

Forecasting and Hindcasting PFAS Concentrations in Groundwater Discharging to Streams near a PFAS Production Facility.

Per- and polyfluoroalkyl substances (PFAS) are known to be highly persistent in groundwater, making it vital to develop new approaches to important practical questions such as the time scale for future persistence of PFAS in contaminated groundwater. In the approach presented here, groundwater from beneath streambeds was analyzed for PFAS and age-dated using SF6 and 3H/3He. The results were coupled with groundwater flux measurements in a convolution approach to estimate past and future PFAS concentrations in groundwater discharge to the streams. At our test site near the Cape Fear River (CFR) of North Carolina, PFAS were detected in groundwater up to 43 years old, suggesting that some PFAS entered groundwater immediately or shortly after fluorochemical production began at the nearby Fayetteville Works. Results are consistent with little to no retardation in groundwater for perfluoroethers such as hexafluoropropylene oxide-dimer acid (HFPO-DA) and perfluoro-2-methoxypropanoic acid (PMPA), the two most abundant PFAS, with mean concentrations of 229 and 498 ng/L, respectively. Future PFAS concentrations in groundwater discharge to streams were estimated to remain above current MCL or health advisory levels through at least 2050 or 2060 (using 3H/3He and SF6, respectively). Recent atmospheric deposition data suggest lower but non-negligible amounts of PFAS may continue to enter groundwater, likely further extending PFAS persistence in groundwater and the adjacent CFR. This approach shows promise for giving an overall perspective on persistence of PFAS in groundwater discharge from a broad contaminated area.

Unraveling brain palmitic acid: Origin, levels and metabolic fate.

In the human brain, palmitic acid (16:0; PAM) comprises nearly half of total brain saturates and has been identified as the third most abundant fatty acid overall. Brain PAM supports the structure of membrane phospholipids, provides energy, and regulates protein stability. Sources underlying the origin of brain PAM are both diet and endogenous synthesis via de novo lipogenesis (DNL), primarily from glucose. However, studies investigating the origin of brain PAM are limited to tracer studies utilizing labelled (14C/11C/3H/2H) PAM, and results vary based on the model and tracer used. Nevertheless, there is evidence PAM is synthesized locally in the brain, in addition to obtained directly from the diet. Herein, we provide an overview of brain PAM origin, entry to the brain, metabolic fate, and factors influencing brain PAM kinetics and levels, the latter in the context of age, as well as neurological diseases and psychiatric disorders. Additionally, we briefly summarize the role of PAM in signaling at the level of the brain. We add to the literature a rudimentary summary on brain PAM metabolism.

Adsorption of imazamox in California agricultural soils and implications for branched broomrape (Phelipanche ramosa) management.

Results of previous research on chemigated imazamox for control of branched broomrape (Phelipanche ramosa) in processing tomatoes suggested potential soil-type differences in imazamox availability. Over two years, there were differences in crop-injury between two sites less than 30-km apart: imazamox-treated tomatoes in the Davis location had relatively minor early season injury while tomatoes at the Woodland location were severely injured or killed. The following study was conducted to investigate imazamox sorption in four California soils to determine if differences in herbicide adsorption played a role in variable crop-injury observed in the field trials. To determine the sorption capacity of imazamox of each soil, a batch-equilibrium study was conducted. There were significant differences in sorbed imazamox: the clay soil had the highest adsorption (Robert's Island: 742.5 pg µL-1 sorbed), followed by the sandy loam soil (Ripon: 723.9 pg µL-1 sorbed), while the loam soils from both trial sites (Davis: 704.2 pg µL-1 sorbed; Woodland: 699.9 pg µL-1 sorbed) had the lowest adsorption and were not significantly different from one another. Results from this study illustrate only minor differences in imazamox adsorption among the soils tested which suggests that soil type was likely not a major factor contributing to differences in crop-injury.

Optimization of Exon-Skipping Riboswitches and Their Applications to Control Mammalian Cell Fate.

Mammalian riboswitches that can regulate transgene expression via RNA-small molecule interaction have promising applications in medicine and biotechnology, as they involve no protein factors that can induce immunogenic reactions and are not dependent on specially engineered promoters. However, the lack of cell-permeable and low-toxicity small molecules and cognate aptamers that can be exploited as riboswitches and the modest switching performance of mammalian riboswitches have limited their applications. In this study, we systematically optimized the design of a riboswitch that regulates exon skipping via an RNA aptamer that binds ASP2905. We examined two design strategies to modulate the stability of the aptamer base stem that blocks the 5' splice site to fine-tune the riboswitch characteristics. Furthermore, an optimized riboswitch was used to generate a mouse embryonic stem cell line that can be chemically induced to differentiate into myogenic cells by activating Myod1 expression and a human embryonic kidney cell line that can be induced to trigger apoptosis by activating BAX expression. The results demonstrate the tight chemical regulation of transgenes in mammalian cells to control their phenotype without exogenous protein factors.