Bacillus thuringiensis (Bt) microbial pesticides have a 50-year history of safety in agriculture. Cry proteins are among the active insecticidal ingredients in these pesticides, and genes coding for ...Cry proteins have been introduced into agricultural crops using modern biotechnology. The Cry gene sequences are often modified to enable effective expression in planta and several Cry proteins have been modified to increase biological activity against the target pest(s). Additionally, the domains of different but structurally conserved Cry proteins can be combined to produce chimeric proteins with enhanced insecticidal properties. Environmental studies are performed and include invertebrates, mammals, and avian species. Mammalian studies used to support the food and feed safety assessment are also used to support the wild mammal assessment. In addition to the NTO assessment, the environmental assessment includes a comparative assessment between the Bt crop and the appropriate conventional control that is genetically similar but lacks the introduced trait to address unintended effects. Specific phenotypic, agronomic, and ecological characteristics are measured in the Bt crop and the conventional control to evaluate whether the introduction of the insect resistance has resulted in any changes that might cause ecological harm in terms of altered weed characteristics, susceptibility to pests, or adverse environmental impact. Additionally, environmental interaction data are collected in field experiments for Bt crop to evaluate potential adverse effects. Further to the agronomic and phenotypic evaluation, potential movement of transgenes from a genetically modified crop plants into wild relatives is assessed for a new pest resistance gene in a new crop. This review summarizes the evidence for safety of crops containing Cry proteins for humans, livestock, and other non-target organisms.
Mixed matrix membranes (MMMs) for gas separations are traditionally comprised of zeolites dispersed in a polymer matrix in order to improve desired penetrant permeability and selectivity. Zeolites ...have a variety of drawbacks for this application – chiefly, a limited number of possible zeolite structures – that limit their potential for use in MMMs. Metal organic frameworks (MOFs), a relatively new class of microporous materials, are not well studied for use in MMMs. MOFs are an attractive alternative to the use of zeolites in MMMs because the number of possible structures is effectively infinite. In this work, a MOF of copper and terephthalic acid (CuTPA) was synthesized, characterized, and used to make MMMs. The gas transport properties of these CuTPA MMMs showed improvements over the pure polymer gas transport properties.
•COVID-19 affected data collection for the Current Population Survey (CPS).•Between March-June 2020 the nonresponse rate increased by 58 percent.•Between March-June 2020, the size of entering cohorts ...declined by 37 percent.•We generated a counterfactual group of “missing” respondents for April-August 2020.•The official unemployment rate was 0.5 to 0.7 percentage points too low.•The official labor force participation rate was 0.4 to 0.8 percentage points too high.
The COVID-19 pandemic significantly affected data collection for the nation's primary source of household-level labor force data, the Current Population Survey (CPS). In the first four months of the pandemic period (March-June 2020) the average month-over-month nonresponse rate increased by 58 percent, while the size of newly entering cohorts declined by 37 percent relative to the prior 15 months. Together, these factors reduced the overall sample size of the CPS by around 16 percent. We hypothesize that these changes, and significant associated shifts in the demographic composition of the sample, were caused by the cessation of in-person interviewing. Geographic variation in nonresponse over this period does not appear related to variation in COVID case rates across metro areas or states. Using this change in interview method as a natural experiment, we compare labor market outcomes of those who entered the survey before and after the start of the COVID pandemic and find that the change in how individuals were recruited into the survey affected estimates of unemployment and labor force participation. In an exercise generating a counterfactual group of “missing” respondents, we estimate that, between April and August of 2020, the average unemployment rate was 0.5 to 0.7 percentage points higher, and the labor force participation rate was 0.4 to 0.8 percentage points lower than estimates using the actual sample of respondents. One implication of these results is that web-based surveys, which are increasingly relied on in empirical labor market studies, may fail to reach important subpopulations of the labor market and that reweighting is unlikely to address the selection on outcomes we document.
The susceptibility of a dietary protein to proteolytic degradation by digestive enzymes, such as gastric pepsin, provides information on the likelihood of systemic exposure to a structurally intact ...and biologically active macromolecule, thus informing on the safety of proteins for human and animal consumption. Therefore, the purpose of standardized in vitro degradation studies that are performed during protein safety assessments is to distinguish whether proteins of interest are susceptible or resistant to pepsin degradation via a study design that enables study-to-study comparison. Attempting to assess pepsin degradation under a wide-range of possible physiological conditions poses a problem because of the lack of robust and consistent data collected under a large-range of sub-optimal conditions, which undermines the needs to harmonize in vitro degradation conditions. This report systematically compares the effects of pH, incubation time, and pepsin-to-substrate protein ratio on the relative degradation of five dietary proteins: three pepsin susceptible proteins ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco), horseradish peroxidase (HRP), hemoglobin (Hb), and two pepsin resistant proteins lipid transfer protein (LTP) and soybean trypsin inhibitor (STI). The results indicate that proteins susceptible to pepsin degradation are readily distinguishable from pepsin-resistant proteins when the reaction conditions are within the well-characterized optima for pepsin. The current standardized in vitro pepsin resistant assay with low pH and high pepsin-to-substrate ratio fits this purpose. Using non-optimal pH and/or pepsin-to-substrate protein ratios resulted in susceptible proteins no longer being reliably degraded by this stomach enzyme, which compromises the ability of this in vitro assay to distinguish between resistant and susceptible proteins and, therefore, no longer providing useful data to an overall weight-of-evidence approach to assessing safety of proteins.
The COVID-19 pandemic significantly affected data collection for the nation's primary source of household-level labor force data, the Current Population Survey (CPS). In the first four months of the ...pandemic period (March-June 2020) the average month-over-month nonresponse rate increased by 58 percent, while the size of newly entering cohorts declined by 37 percent relative to the prior 15 months. Together, these factors reduced the overall sample size of the CPS by around 16 percent. We hypothesize that these changes, and significant associated shifts in the demographic composition of the sample, were caused by the cessation of in-person interviewing. Geographic variation in nonresponse over this period does not appear related to variation in COVID case rates across metro areas or states. Using this change in interview method as a natural experiment, we compare labor market outcomes of those who entered the survey pre- and post-COVID pandemic and find that the change in how individuals were recruited into the survey affected estimates of unemployment and labor force participation. In an exercise generating a counterfactual group of "missing" respondents, we estimate that, between April and August of 2020, the average unemployment rate was 0.5 to 0.7 percentage points higher, and the labor force participation rate was 0.4 to 0.8 percentage points lower than estimates using the actual sample of respondents. One implication of these results is that web-based surveys, which are increasingly relied on in empirical labor market studies, may fail to reach important subpopulations of the labor market and that reweighting is unlikely to address the selection on outcomes we document.
After the Supreme Court ruled school segregation unconstitutional in 1954, southern white backlash seemed to explode overnight. Journalists profiled the rise of a segregationist movement committed to ...preserving the "southern way of life" through a campaign of massive resistance. InDefending White Democracy, Jason Morgan Ward reconsiders the origins of this white resistance, arguing that southern conservatives began mobilizing against civil rights some years earlier, in the era before World War II, when the New Deal politics of the mid-1930s threatened the monopoly on power that whites held in the South.As Ward shows, years before "segregationist" became a badge of honor for civil rights opponents, many white southerners resisted racial change at every turn--launching a preemptive campaign aimed at preserving a social order that they saw as under siege. By the time of theBrowndecision, segregationists had amassed an arsenal of tested tactics and arguments to deploy against the civil rights movement in the coming battles. Connecting the racial controversies of the New Deal era to the more familiar confrontations of the 1950s and 1960s, Ward uncovers a parallel history of segregationist opposition that mirrors the new focus on the long civil rights movement and raises troubling questions about the enduring influence of segregation's defenders.
Mixed matrix membranes (MMMs) with low particle loadings have been shown to improve the properties of pure polymers for many gas separations. Comparatively few reports have been made for high ...particle loading (≥50vol.%) MMMs. In this work, CO₂–CH₄ feeds were used to study the potential of 50vol.% zeolite 4A-poly(vinyl acetate) (PVAc) MMMs for natural gas separations. A low CO₂ partial pressure mixed feed probed MMM performance below the plasticization pressure of PVAc and a high CO₂ partial pressure mixed feed probed MMM performance at industrially relevant conditions above the plasticization pressure. Under both mixed feed conditions at 35°C, substantial improvements in overall separation performance were observed. At low CO₂ partial pressures, CO₂ permeability roughly doubled with a nearly 50% increase in selectivity versus pure PVAc under the same conditions. For the high CO₂ partial pressure feed, CO₂ permeability remained effectively unchanged with a 63% increase in selectivity versus pure PVAc. Surprisingly, the performance of these PVAc based MMMs approached the properties of current “upper bound” polymers. Overall, this work shows that significantly improved performance MMMs can be made with traditional techniques from a low cost, low performance polymer without costly adhesion promoters.
Gly m 4 is a key soybean allergen that causes allergic symptoms in the skin, gastrointestinal tract, or respiratory tract of sensitive individuals. To understand naturally variable levels of Gly m 4 ...among conventional soybean varieties, a sandwich ELISA was developed and validated using a mouse anti-Gly m 4 monoclonal antibody and a goat anti-Gly m 4 polyclonal antibody as capture and detection antibodies, respectively. The ELISA shows high specificity to Gly m 4 without any cross-reactivity to other soybean proteins and has a quantification range of 7.8–250 ng/mL using an Escherichia coli-produced recombinant Gly m 4, with 2.1 ng/mL being the limit of detection. Within the quantification range, the coefficients of variation of the intra-assay and interassay precision are less than 5 and 12%, respectively. Moreover, extraction efficiency and dilutional parallelism experiments were completed to demonstrate the assay is accurate. The validated assay was used to quantify Gly m 4 levels in 128 soybean samples from 24 conventional soybean varieties grown at 8 distinct geographical locations. There was a 13-fold difference between the least and greatest amounts of Gly m 4 concentrations among the samples, and the results demonstrate that the most significant sources of variability in Gly m 4 levels in the conventional varieties were related to location and variety.
PDF
