The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu.

Objectives: Fatalities due to being left in motor vehicles is an important cause of pediatric mortality. Few studies in the medical literature focus on this topic. This study aims to describe the circumstances surrounding these deaths, to determine their geographic distribution, and to evaluate the legal consequences for those responsible.Methods: This is a retrospective cohort study of individuals ≤14 years old who died of heatstroke after being left in motor vehicles from 1990 through 2016 using a database provided by KidsAndCars.org. Descriptive data and specified outcomes regarding victims and responsible individuals were recorded.Results: Of the 541 cases included for analysis, 528 fatalities involved a single victim and 26 fatalities involved 2 or more victims left in a vehicle. Of all fatalities, 54.4% were male and the mean age was 16.4 (±13.7) months. The responsible individual(s) unknowingly left the victim(s) in the vehicle in 78.2% of cases and knowingly left the victim(s) in 16.6% of cases. A single individual was responsible for leaving the victim(s) in 88.9% of cases. The cases were noted in 45 of 50 states and most commonly occurred in Texas (15%), Florida (12%), and California (7%). Criminal charges against the responsible individual(s) occurred in 58.2% of cases.Conclusions: Pediatric fatalities due to being left in motor vehicles most commonly occur when a caregiver leaves a child unknowingly in a home parking area. These fatalities occur most often in Texas, Florida, and California. Responsible individuals are frequently charged with a crime.

Background: Screening for COVID-19 infection in pediatrics is challenging as its clinical presentation may be asymptomatic or mimic other common childhood infections. We examined the use of a COVID-19 screening protocol (CSP) in the pediatric emergency department (PED) to determine the incidence of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) tests in patients who are CSP+ and CSP-.Methods: We conducted a retrospective cohort study of pediatric patients with SARS-CoV-2 testing completed in an urban tertiary care PED from November 1 to December 31, 2020. Demographics, CSP designation, test results, and disposition were compared. Statistical significance was determined using chisquare or a comparison of means. Sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV) with 95% confidence intervals (CI) were calculated.Results: A total of 1,613 patients had SARS-CoV-2 tests completed with 9.1% (N=147) having positive test results. Of 1,014 (62.9%) patients who were CSP+, 12.9% tested positive. Comparatively, 599 (37.1%) patients were CSP-with only 2.7% positive tests, p<0.0001. The sensitivity, specificity, NPV, and PPV of the CSP in all tested patients were 89.1%, 39.8%, 97.3%, and 12.9%, respectively. Of tested patients, 887 (55.0%) were admitted to the hospital and were more likely to be positive if CSP+, p≤0.001. Within the admitted group, 16.8% were admitted to the operating room, of whom 83.9% were CSP-with 4.0% testing positive for SARS-CoV-2.Conclusions: COVID-19 screening in the pediatric population is a useful modality to risk stratify most patients presenting to the PED for the purpose of selective testing and guiding personal protective equipment use. This may be particularly useful in low-resource settings.