Predicting thresholds for population replacement gene drives.

BACKGROUND: Threshold-dependent gene drives (TDGDs) could be used to spread desirable traits through a population, and are likely to be less invasive and easier to control than threshold-independent gene drives. Engineered Genetic Incompatibility (EGI) is an extreme underdominance system previously demonstrated in Drosophila melanogaster that can function as a TDGD when EGI agents of both sexes are released into a wild-type population. RESULTS: Here we use a single generation fitness assay to compare the fecundity, mating preferences, and temperature-dependent relative fitness to wild-type of two distinct genotypes of EGI agents. We find significant differences in the behavior/performance of these EGI agents that would not be predicted a priori based on their genetic design. We report a surprising temperature-dependent change in the predicted threshold for population replacement in an EGI agent that drives ectopic expression of the developmental morphogen pyramus. CONCLUSIONS: The single-generation fitness assay presented here could reduce the amount of time required to estimate the threshold for TDGD strategies for which hybrid genotypes are inviable. Additionally, this work underscores the importance of empirical characterization of multiple engineered lines, as behavioral differences can arise in unique genotypes for unknown reasons.

Describing and exploring physical activity experiences among adults with cancer during the COVID-19 pandemic: a mixed-methods survey study.

Understanding if (and how) adults with cancer perceived their physical activity (PA) levels have changed (or not) since the COVID-19 pandemic and why this may have occurred is important. Given current gaps in knowledge, the purpose of this study was to explore PA experiences among adults with cancer amidst the COVID-19 pandemic. Individuals were eligible if they were currently ≥19 years of age, had been diagnosed with cancer ≥18 years of age, and were living in Canada. 113 adults affected by cancer (Mage = 61.9 ± 12.7 years; 68% female) completed the survey which asked closed- and open-ended questions about PA levels and PA engagement experiences. Most participants (n = 76, 67.3%) were not meeting PA guidelines, and reported engaging in, on average, 89.2 ± 138.2 minutes per week of moderate-to-vigorous PA. Participants indicated their PA declined (n = 55, 38.7%), did not change (n = 40, 35.4%), or increased (n = 18, 15.9%) since the start of the pandemic. Participants described their changed PA as due to public health restrictions, lowered motivation during the pandemic, or cancer- and treatment-related effects. For those engaging in similar or greater PA, online home-based and outdoor PA were shared as main forms of PA. Findings suggest PA behavior change support and ongoing access to online, home-based and outdoor PA options will be required as pandemic restrictions ease in this population.

Describing Supportive Care Programming Access and Comfort Gathering through the COVID-19 Pandemic: An Observational Mixed Methods Study with Adults Affected by Cancer.

Supportive care programming helps many adults affected by cancer manage concerns related to their disease. Public health restrictions imposed by the COVID-19 pandemic have undoubtedly changed the nature of supportive care programming delivery. Yet, access to supportive care programming and comfort gathering through the pandemic are unknown. As a first step towards informing ongoing supportive care programming for adults affected by cancer, this observational, mixed methods study described supportive care programming access through the COVID-19 pandemic and comfort returning to in-person supportive care programming as restrictions eased. Adults affected by cancer (n = 113; mean age = 61.9 ± 12.7 years; 68% female) completed an online survey, and descriptive statistics were computed. A purposeful sample of survey participants (n = 12; mean age = 58.0 ± 14.5 years; 58% female) was subsequently recruited to complete semi-structured interviews. Interviews were analyzed using reflexive thematic analysis. Less than half (41.6%) of the survey sample reported accessing supportive care programming during the pandemic, and of those who had accessed supportive care programming, most (65.6%) perceived similar or greater access than pre-pandemic. During interviews, participants described the ways online delivery enhanced their access and reduced barriers to supportive care programming. However, physical activity programming was described as challenging to navigate online. With restrictions easing, most of the survey sample (56.6%) reported being apprehensive about returning to in-person supportive care programming and identified the protocols that would make them feel safe to gather. During interviews, participants recounted struggling to balance their need for social connection with their health and safety. This study provides evidence to inform supportive care programming for adults affected by cancer through the COVID-19 pandemic. Findings suggest online delivery can enhance access to some types of supportive care programming for some adults affected by cancer, and that efforts are needed to ensure all adults affected by cancer feel comfortable gathering in-person.

Genetically engineered insects with sex-selection and genetic incompatibility enable population suppression.

Engineered Genetic Incompatibility (EGI) is a method to create species-like barriers to sexual reproduction. It has applications in pest control that mimic Sterile Insect Technique when only EGI males are released. This can be facilitated by introducing conditional female-lethality to EGI strains to generate a sex-sorting incompatible male system (SSIMS). Here, we demonstrate a proof of concept by combining tetracycline-controlled female lethality constructs with a pyramus-targeting EGI line in the model insect Drosophila melanogaster. We show that both functions (incompatibility and sex-sorting) are robustly maintained in the SSIMS line and that this approach is effective for population suppression in cage experiments. Further we show that SSIMS males remain competitive with wild-type males for reproduction with wild-type females, including at the level of sperm competition.