Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Hindsight bias magnifies escalation of commitment

I conducted a 3 (Project Outcome: success, neutral, failure) x 3 (Information Amount: small, medium, large) factorial experiment in order to investigate whether observer\u27s perception of escalation of commitment falls victim to hindsight bias. Subjects observed a decision-maker making an investment decision and persisting it in the face of negative information when the project was 50% completed and 90% completed. Later, subjects learned the project outcome and answered questions measuring their perception of the investment project and the decision-maker, as if they did not know the outcome already. Results confirmed my hypothesis. Participant\u27s postdicted ratings of the chosen project and the decision-maker were influenced significantly by project outcome. Those who observed a successful outcome rated the chosen project as more likely to succeed and the decision-maker as a more qualified leader than those who observed neutral or failure investments. Subjects also reported that they would have continued to invest in the project under negative information if they were the decision-maker. Results provide insights to organizational leaders so they will show courage to guard against premature project termination

AGTR1 A1166C gene polymorphism is associated with the effectiveness of valsartan monotherapy in Chinese patients with essential hypertension: A retrospective analysis

Objective: To investigate whether angiotensin II type 1 receptor (AGTR1 A1166C) gene polymorphism was associated with the effectiveness of valsartan monotherapy in Chinese patients with essential hypertension. Methods: This retrospective analysis included 198 patients (⩾18 years of age) who received valsartan monotherapy (80 mg/day) for newly developed essential hypertension at the authors’ center between January 1, 2020 and December 31, 2023. Genotyping for AGTR1 A1166C gene polymorphism was done by polymerase chain reaction (PCR)-melting curve analysis of genomic DNA from peripheral blood samples. A dominant genetic model for AGTR1 A1166C (AA genotype versus AC + CC genotype) was used. Multivariate regression analysis of baseline variables and AGTR1 polymorphism was conducted to identify predictors of target blood pressure attainment (<140/90 mmHg) at the 4-week follow-up. Results: The median age of the 198 patients was (53.7±13.5) years, and 58% were men. Genotyping assays showed that 164 patients had the AA genotype, and 34 patients were of the AC/CC genotype, including 30 with the AC genotype and 4 with the CC genotype. Allele distribution was consistent with Hardy Weinberg equilibrium. 109 Patients (55.1%) attained the blood pressure target. Multivariate analysis showed that smoking (versus no smoking, HR 0.314, 95% CI 0.159-0.619, P=0.001) and AGTR1 A1166C AA genotype (versus AC/CC, HR 2.927, 95% CI 1.296-6.611, P=0.023) were significant and independent predictors of target attainment. 25 Patients (73.5%) with AGTR1 A1166C AC/CC genotype attained the target versus 51.2% (51/164) of patients with AGTR1 A1166C AA genotype (P=0.017). Patients with AGTR1 A1166C AC/CC genotype had a significantly greater reduction in systolic blood pressure [(33.1±10.8) mmHg versus (29.2±11.7) mmHg in AA carriers; P=0.029)]. Conclusions: Hypertensive patients carrying one or two C alleles of the AGTR1 A1166C gene were more responsive to valsartan treatment

The evolutionary history of small RNAs in Solanaceae.

The Solanaceae or nightshade family is an economically important group with remarkable diversity. To gain a better understanding of how the unique biology of the Solanaceae relates to the familys small RNA (sRNA) genomic landscape, we downloaded over 255 publicly available sRNA data sets that comprise over 2.6 billion reads of sequence data. We applied a suite of computational tools to predict and annotate two major sRNA classes: (1) microRNAs (miRNAs), typically 20- to 22-nucleotide (nt) RNAs generated from a hairpin precursor and functioning in gene silencing and (2) short interfering RNAs (siRNAs), including 24-nt heterochromatic siRNAs typically functioning to repress repetitive regions of the genome via RNA-directed DNA methylation, as well as secondary phased siRNAs and trans-acting siRNAs generated via miRNA-directed cleavage of a polymerase II-derived RNA precursor. Our analyses described thousands of sRNA loci, including poorly understood clusters of 22-nt siRNAs that accumulate during viral infection. The birth, death, expansion, and contraction of these sRNA loci are dynamic evolutionary processes that characterize the Solanaceae family. These analyses indicate that individuals within the same genus share similar sRNA landscapes, whereas comparisons between distinct genera within the Solanaceae reveal relatively few commonalities