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The house mouse X and Y chromosomes have recently acquired multicopy, rapidly evolving gene families representing an evolutionary arms race. This arms race between proteins encoded by X-linkedSlxl1/Slxand Y-linkedSlygene families can distort offspring sex ratio, but how these proteins compete remains unknown. Here, we report howSlxl1/SlxandSlyencoded proteins compete in a protein family–specific and dose-dependent manner using yeast. Specifically, SLXL1 competes with SLY1 and SLY2 for binding to the Spindlin SPIN1. Similarly, SLX competes with SLY2 for binding the Spindlin SSTY2. These competitions are driven by the N termini of SLXL1, SLX, SLY1, and SLY2 binding to the third Tudor domains of SPIN1 and SSTY2. SLY1 and SLY2 form homo- and heterodimers, suggesting that the competition is between complex multimers. Residues under positive selection mapping to the interaction domains and rapid exon gain/loss are consistent with competition between the X- and Y-linked gene families. Our findings support a model in which dose-dependent competition of these X- and Y-linked encoded proteins to bind Spindlins occurs in haploid X- and Y-spermatids to influence X- versus Y-sperm fitness and thus sex ratio.more » « lessFree, publicly-accessible full text available February 18, 2026
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Free, publicly-accessible full text available January 14, 2026
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Free, publicly-accessible full text available August 21, 2025
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Eukaryotic phytoplankton, also known as algae, form the basis of marine food webs and drive marine carbon sequestration. Algae must regulate their motility and gravitational sinking to balance access to light at the surface and nutrients in deeper layers. However, the regulation of gravitational sinking remains largely unknown, especially in motile species. Here, we quantify gravitational sinking velocities according to Stokes’ law in diverse clades of unicellular marine microalgae to reveal the cell size, density, and nutrient dependency of sinking velocities. We identify a motile algal species,Tetraselmissp., that sinks faster when starved due to a photosynthesis-driven accumulation of carbohydrates and a loss of intracellular water, both of which increase cell density. Moreover, the regulation of cell sinking velocities is connected to proliferation and can respond to multiple nutrients. Overall, our work elucidates how cell size and density respond to environmental conditions to drive the vertical migration of motile algae.more » « less
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The power and scope of disease modeling can be markedly enhanced through the incorporation of broad genetic diversity. The introduction of pathogenic mutations into a single inbred mouse strain sometimes fails to mimic human disease. We describe a cross-species precision disease modeling platform that exploits mouse genetic diversity to bridge cell-based modeling with whole organism analysis. We developed a universal protocol that permitted robust and reproducible neural differentiation of genetically diverse human and mouse pluripotent stem cell lines and then carried out a proof-of-concept study of the neurodevelopmental geneDYRK1A. Results in vitro reliably predicted the effects of genetic background onDyrk1aloss-of-function phenotypes in vivo. Transcriptomic comparison of responsive and unresponsive strains identified molecular pathways conferring sensitivity or resilience toDyrk1a1Aloss and highlighted differential messenger RNA isoform usage as an important determinant of response. This cross-species strategy provides a powerful tool in the functional analysis of candidate disease variants identified through human genetic studies.more » « less
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Nuclear import of the hepatitis B virus (HBV) nucleocapsid is essential for replication that occurs in the nucleus. The ~360-angstrom HBV capsid translocates to the nuclear pore complex (NPC) as an intact particle, hijacking human importins in a reaction stimulated by host kinases. This paper describes the mechanisms of HBV capsid recognition by importins. We found that importin α1 binds a nuclear localization signal (NLS) at the far end of the HBV coat protein Cp183 carboxyl-terminal domain (CTD). This NLS is exposed to the capsid surface through a pore at the icosahedral quasi-sixfold vertex. Phosphorylation at serine-155, serine-162, and serine-170 promotes CTD compaction but does not affect the affinity for importin α1. The binding of 30 importin α1/β1 augments HBV capsid diameter to ~620 angstroms, close to the maximum size trafficable through the NPC. We propose that phosphorylation favors CTD externalization and prompts its compaction at the capsid surface, exposing the NLS to importins.more » « less
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N/A (Ed.)Abstract Medicago truncatulais a model legume that has been extensively investigated in diverse subdisciplines of plant science.Medicago littoraliscan interbreed withM. truncatulaandM. italica; these three closely related species form a clade, i.e. TLI clade. Genetic studies have indicated thatM. truncatulaaccessions are heterogeneous but their taxonomic identities have not been verified. To elucidate the phylogenetic position of diverseM. truncatulaaccessions within the genus, we assembled 54 plastid genomes (plastomes) using publicly available next-generation sequencing data and conducted phylogenetic analyses using maximum likelihood. Five accessions showed high levels of plastid DNA polymorphism. Three of these highly polymorphic accessions contained sequences from bothM. truncatulaandM. littoralis.Phylogenetic analyses of sequences placed some accessions closer to distantly related species suggesting misidentification of source material.Most accessions were placed within the TLI clade and maximally supported the interrelationships of three subclades. TwoMedicagoaccessions were placed within aM. italicasubclade of the TLI clade. Plastomes with a 45-kb (rpl20-ycf1) inversion were placed within theM. littoralissubclade. Our results suggest that theM. truncatulaaccession genome pool represents more than one species due to possible mistaken identities and gene flow among closely related species.more » « less
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Background: Researcher-practitioner partnerships (RPPs) have gained increasing prominence within education, since they are crucial for identifying partners’ problems of practice and seeking solutions for improving district (or school) problems. The CS Pathways RPP project brought together researchers and practitioners, including middle school teachers and administrators from three urban school districts, to build teachers’ capacity to implement an inclusive computer science and digital literacy (CSDL) curriculum for all students in their middle schools. Objective: This study explored the teachers’ self-efficacy development in teaching a middle school CSDL curriculum under the project’s RPP framework. The ultimate goal was to gain insights into how the project’s RPP framework and its professional development (PD) program supported teachers’ self-efficacy development, in particular its challenges and success of the partnership. Method: Teacher participants attended the first-year PD program and were surveyed and/or interviewed about their self-efficacy in teaching CSDL curriculum, spanning topics ranging from digital literacy skills to app creation ability and curriculum implementation. Both survey and interview data were collected and analyzed using mixed methods 1) to examine the reach of the RPP PD program in terms of teachers’ self-efficacy; 2) to produce insightful understandings of the PD program impact on the project’s goal of building teachers’ self-efficacy. Results and Discussion: We reported the teachers’ self-efficacy profiles based on the survey data. A post-survey indicated that a majority of the teachers have high self-efficacy in teaching the CSDL curriculum addressed by the RPP PD program. Our analysis identified five critical benefits the project’s RPP PD program provided, namely collaborative efforts on resource and infrastructure building, content and pedagogical knowledge growth, collaboration and communication, and building teacher identity. All five features have shown direct impacts on teachers' self-efficacy. The study also reported teachers’ perceptions on the challenges they faced and potential areas for improvements. These findings indicate some important features of an effective PD program, informing the primary design of an RPP CS PD program.more » « less