The consequence of ATP synthase dimer angle on mitochondrial morphology studied by cryo-electron tomography.

Mitochondrial ATP synthases form rows of dimers, which induce membrane curvature to give cristae their characteristic lamellar or tubular morphology. The angle formed between the central stalks of ATP synthase dimers varies between species. Using cryo-electron tomography and sub-tomogram averaging, we determined the structure of the ATP synthase dimer from the nematode worm C. elegans and show that the dimer angle differs from previously determined structures. The consequences of this species-specific difference at the dimer interface were investigated by comparing C. elegans and S. cerevisiae mitochondrial morphology. We reveal that C. elegans has a larger ATP synthase dimer angle with more lamellar (flatter) cristae when compared to yeast. The underlying cause of this difference was investigated by generating an atomic model of the C. elegans ATP synthase dimer by homology modelling. A comparison of our C. elegans model to an existing S. cerevisiae structure reveals the presence of extensions and rearrangements in C. elegans subunits associated with maintaining the dimer interface. We speculate that increasing dimer angles could provide an advantage for species that inhabit variable-oxygen environments by forming flatter more energetically efficient cristae.

Maintenance of complex I and its supercomplexes by NDUF-11 is essential for mitochondrial structure, function and health.

Mitochondrial supercomplexes form around a conserved core of monomeric complex I and dimeric complex III; wherein a subunit of the former, NDUFA11, is conspicuously situated at the interface. We identified nduf-11 (B0491.5) as encoding the Caenorhabditis elegans homologue of NDUFA11. Animals homozygous for a CRISPR-Cas9-generated knockout allele of nduf-11 arrested at the second larval (L2) development stage. Reducing (but not eliminating) expression using RNAi allowed development to adulthood, enabling characterisation of the consequences: destabilisation of complex I and its supercomplexes and perturbation of respiratory function. The loss of NADH dehydrogenase activity was compensated by enhanced complex II activity, with the potential for detrimental reactive oxygen species (ROS) production. Cryo-electron tomography highlighted aberrant morphology of cristae and widening of both cristae junctions and the intermembrane space. The requirement of NDUF-11 for balanced respiration, mitochondrial morphology and development presumably arises due to its involvement in complex I and supercomplex maintenance. This highlights the importance of respiratory complex integrity for health and the potential for its perturbation to cause mitochondrial disease. This article has an associated First Person interview with Amber Knapp-Wilson, joint first author of the paper.

Art Therapy, Community Building, Activism, and Outcomes.

This article is a descriptive study of two groups who came together through service-learning: The first group is graduate art therapy students enrolled in a research class, who partnered with six community agencies to help them prepare assignments for undergraduate service-learning students in a subsequent semester. The art therapy research students also assisted the agencies with program evaluation. The second group is the six directors of the community agencies who were preparing for service-learning students enrolled in an art history class titled Art as A Social Practice. Service-learning is an experiential pedagogy where community service is integrated into an academic course, and where the services performed meet genuine community needs. The hyphen in service-learning represents the ideal that both the students and community agencies experience benefits from the relationship, although in reality, it is often the experiences of the students rather than the agencies that receive greater attention in the scholarly research literature. The present article places focus on the community agencies that, in the process of planning for service-learners, made two unexpected requests: First they requested that the service-learners stay longer than one semester, and secondly, they requested assistance with evaluating the effectiveness of their programs. This article is about the efforts to respond to these requests through the assistance of art therapy research students. With growing trends in community-based art therapy practice, greater attention to the community agencies where art therapists work is necessary and valuable to art therapy preparation. The present article describes six distinctive communities, illustrating new frontiers of practice. The research students' experiences and the experiences of the community partners were assessed using qualitative methods that included pre and post-questionnaires, written reflections of students, interviews of agency directors and agency, student, and researcher focus group transcripts. This study will inform other art therapy programs who may want to use a service-learning approach to teaching research. A discussion of the promising practices of service-learning and research, as well as the challenges leads to recommendations for art therapy education.