The synaptonemal complex (SC) is a protein-rich structure essential for meiotic recombination and faithful chromosome segregation. Acting like a zipper to paired homologous chromosomes during early prophase I, the complex is a symmetrical structure where central elements are connected on two sides by the transverse filaments to the chromatin-anchoring lateral elements. Despite being found in most major eukaryotic taxa implying a deeply conserved evolutionary origin, several components of the complex exhibit unusually high rates of sequence turnover. This is puzzlingly exemplified by the SC of Drosophila, where the central elements and transverse filaments display no identifiable homologs outside of the genus. Here, we exhaustively examine the evolutionary history of the SC in Drosophila taking a comparative phylogenomic approach with high species density to circumvent obscured homology due to rapid sequence evolution. Contrasting starkly against other genes involved in meiotic chromosome pairing, SC genes show significantly elevated rates of coding evolution due to a combination of relaxed constraint and recurrent, widespread positive selection. In particular, the central element cona and transverse filament c(3)G have diversified through tandem and retro-duplications, repeatedly generating paralogs with novel germline activity. In a striking case of molecular convergence, c(3)G paralogs that independently arose in distant lineages evolved under positive selection to have convergent truncations to the protein termini and elevated testes expression. Surprisingly, the expression of SC genes in the germline is prone to change suggesting recurrent regulatory evolution which, in many species, resulted in high testes expression even though Drosophila males are achiasmic. Overall, our study recapitulates the poor conservation of SC components, and further uncovers that the lack of conservation extends to other modalities including copy number, genomic locale, and germline regulation. Considering the elevated testes expression in many Drosophila species and the common ancestor, we suggest that the activity of SC genes in the male germline, while still poorly understood, may be a prime target of constant evolutionary pressures driving repeated adaptations and innovations.

Background/Objectives: Several randomized controlled trials have found that dietary interventions promoting self-guided shifts away from ultra-processed foods (UPFs) and toward minimally processed, nutrient-dense foods may alleviate depressive symptoms. However, translating these interventions into scalable and sustainable real-world approaches remains a key challenge. Adopting a minimally processed dietary pattern requires sustained effort (e.g., meal planning, shopping, and preparation) within environments where UPFs are pervasive and convenient. These demands may be especially burdensome for individuals experiencing depressive symptoms. Consequently, interventions that rely heavily on individual effort may be difficult to maintain. Commercial meal delivery services may offer a structural solution by reducing logistical and cognitive barriers to dietary change, yet little is known about how individuals with depressive symptoms experience this approach. Methods: In a parent study, we conducted a randomized pilot study of a meal delivery service designed to provide minimally processed meals to adults with moderate to moderately severe depressive symptoms; here we report qualitative findings from post-intervention interviews with participants assigned to the meal delivery condition (n = 20). Results: Participants appreciated reductions in preparatory effort and mental load, which supported adherence. Dietary changes were also linked to improved mood through increased energy, mood stability, and more positive self-evaluation. However, social settings were a near-universal barrier, and acceptability depended on palatability, compatibility with personal preferences, and perceived autonomy. Several participants also described a temporal adjustment process (early cravings/withdrawal followed by adaptation). Conclusions: Overall, these findings suggest participant-informed priorities for future testing and refinement of scalable meal delivery interventions for depression, including personalization and choice, quality control, and support for social and withdrawal-related challenges.