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OBJECTIVE: ACTN2, encoding alpha-actinin-2, is essential for cardiac and skeletal muscle sarcomeric function. ACTN2 variants are a known cause of cardiomyopathy without skeletal muscle involvement. Recently, specific dominant monoallelic variants were reported as a rare cause of core myopathy of variable clinical onset, although the pathomechanism remains to be elucidated. The possibility of a recessively inherited ACTN2-myopathy has also been proposed in a single series. METHODS: We provide clinical, imaging, and histological characterization of a series of patients with a novel biallelic ACTN2 variant. RESULTS: We report seven patients from five families with a recurring biallelic variant in ACTN2: c.1516A>G (p.Arg506Gly), all manifesting with a consistent phenotype of asymmetric, progressive, proximal, and distal lower extremity predominant muscle weakness. None of the patients have cardiomyopathy or respiratory insufficiency. Notably, all patients report Palestinian ethnicity, suggesting a possible founder ACTN2 variant, which was confirmed through haplotype analysis in two families. Muscle biopsies reveal an underlying myopathic process with disruption of the intermyofibrillar architecture, Type I fiber predominance and atrophy. MRI of the lower extremities demonstrate a distinct pattern of asymmetric muscle involvement with selective involvement of the hamstrings and adductors in the thigh, and anterior tibial group and soleus in the lower leg. Using an in vitro splicing assay, we show that c.1516A>G ACTN2 does not impair normal splicing. INTERPRETATION: This series further establishes ACTN2 as a muscle disease gene, now also including variants with a recessive inheritance mode, and expands the clinical spectrum of actinopathies to adult-onset progressive muscle disease.

Prime editing is a powerful means of introducing precise changes to specific locations in mammalian genomes. However, the widely varying efficiency of prime editing across target sites of interest has limited its adoption in the context of both basic research and clinical settings. Here, we set out to exhaustively characterize the impact of the cis- chromatin environment on prime editing efficiency. Using a newly developed and highly sensitive method for mapping the genomic locations of a randomly integrated "sensor", we identify specific epigenetic features that strongly correlate with the highly variable efficiency of prime editing across different genomic locations. Next, to assess the interaction of trans -acting factors with the cis -chromatin environment, we develop and apply a pooled genetic screening approach with which the impact of knocking down various DNA repair factors on prime editing efficiency can be stratified by cis -chromatin context. Finally, we demonstrate that we can dramatically modulate the efficiency of prime editing through epigenome editing, i.e. altering chromatin state in a locus-specific manner in order to increase or decrease the efficiency of prime editing at a target site. Looking forward, we envision that the insights and tools described here will broaden the range of both basic research and therapeutic contexts in which prime editing is useful.

BACKGROUND: Valosin-containing protein (VCP) disease, caused by mutations in the VCP gene, results in myopathy, Pagets disease of bone (PBD) and frontotemporal dementia (FTD). Natural history and genotype-phenotype correlation data are limited. This study characterises patients with mutations in VCP gene and investigates genotype-phenotype correlations. METHODS: Descriptive retrospective international study collecting clinical and genetic data of patients with mutations in the VCP gene. RESULTS: Two hundred and fifty-five patients (70.0% males) were included in the study. Mean age was 56.8±9.6 years and mean age of onset 45.6±9.3 years. Mean diagnostic delay was 7.7±6 years. Symmetric lower limb weakness was reported in 50% at onset progressing to generalised muscle weakness. Other common symptoms were ventilatory insufficiency 40.3%, PDB 28.2%, dysautonomia 21.4% and FTD 14.3%. Fifty-seven genetic variants were identified, 18 of these no previously reported. c.464G>A (p.Arg155His) was the most frequent variant, identified in the 28%. Full time wheelchair users accounted for 19.1% with a median time from disease onset to been wheelchair user of 8.5 years. Variant c.463C>T (p.Arg155Cys) showed an earlier onset (37.8±7.6 year) and a higher frequency of axial and upper limb weakness, scapular winging and cognitive impairment. Forced vital capacity (FVC) below 50% was as risk factor for being full-time wheelchair user, while FVC

With changing climate, many species are projected to move poleward or to higher elevations to track suitable climates. The prediction that species will move poleward assumes that geographically marginal populations are at the edge of the species' climatic range. We studied Pinus coulteri from the center to the northern (poleward) edge of its range, and examined three scenarios regarding the relationship between the geographic and climatic margins of a species' range. We used herbarium and iNaturalist.org records to identify P. coulteri sites, generated a species distribution model based on temperature, precipitation, climatic water deficit, and actual evapotranspiration, and projected suitability under future climate scenarios. In fourteen populations from the central to northern portions of the range, we conducted field studies and recorded elevation, slope and aspect (to estimate solar insolation) to examine relationships between local and regional distributions. We found that northern populations of P. coulteri do not occupy the cold or wet edge of the species' climatic range; mid-latitude, high elevation populations occupy the cold margin. Aspect and insolation of P. coulteri populations changed significantly across latitudes and elevations. Unexpectedly, northern, low-elevation stands occupy north-facing aspects and receive low insolation, while central, high-elevation stands grow on more south-facing aspects that receive higher insolation. Modeled future climate suitability is projected to be highest in the central, high elevation portion of the species range, and in low-lying coastal regions under some scenarios, with declining suitability in northern areas under most future scenarios. For P. coulteri, the lack of high elevation habitat combined with a major dispersal barrier may limit northward movement in response to a warming climate. Our analyses demonstrate the importance of distinguishing geographically vs. climatically marginal populations, and the importance of quantitative analysis of the realized climate space to understand species range limits.

Nitrogen remobilization is essential for nitrogen economy at the whole plant level. 15N tracing experiments showed that the Arabidopsis leaf to leaf N-remobilisation at vegetative stage was mainly determined by leaf senescence severity while N-remobilisation from rosette to seeds is depending on harvest index (Diaz et al. 2008). N-remobilisation efficiency to the seeds was higher in N limiting conditions (Lemaître et al. 2008). In order to investigate natural variation of nitrogen uptake and remobilisation in Arabidopsis, a core collection of accessions was grown at low (N-) and high (N+) nitrate supplies. Plants were labelled using 15N nitrate and traits measured (15N partition, nitrogen concentrations, remobilisation, biomass, yield, flowering). Globally, it was observed that the late-flowering plants had higher vegetative biomass, lower seed biomass and heavier seeds at both N+ and N- conditions. As a result, the late-flowering genotypes had lower harvest index (HI), higher nitrogen harvest index (NHI), higher 15N partitioning in seeds (15NHI), and lower fertility. All the accessions studied responded to low nitrogen nutrition by decreasing plant biomass, by lowering the amount of residual nitrogen lost in the dry remains (N%DR), and by increasing N-remobilisation (15NHI) and allocation of post-labelling assimilated nitrogen to the seeds. The most striking results were provided by the 15N tracing experiments, demonstrating that the amount of 15N, first assimilated into the rosette, and further remobilised to the seeds, is highly dependent on sink/source biomass ratio, i.e. on harvest index. Trait variations allowed us to group accessions in different feature-classes and to detect genotypes showing opposite or extreme behaviours. Results provided will facilitate the choice of recombinant inbred line parents for further QTL experiments. N-remobilisation was investigated for mutants of interest, using the same labelling protocol than for accessions. References : Diaz et al. (2008) Plant Physiology 147 : 1437-1449 Lemaître et al. (2008) Plant Cell Physiology 49(7): 1056-1065

Lifelong learning appears frequently on university statements of desirable graduate outcomes. It is also referred to as a desirable outcome for Australian law graduates. This paper examines academic staff perceptions of lifelong learning as part of a broader study about assessment practices in a recently established Australian law school. Findings indicate that participants value lifelong learning, and that some of their perceptions of assessment principles and practice are broadly aligned with the lifelong learning paradigm. However, responses also indicate a lack of precision about how students' capacity for lifelong learning ought to be developed, as well as a tendency for participants to conflate the "self-management" component of lifelong learning with a more traditional, higher education concept of learner autonomy. The paper argues that imprecision and confusion about how to assess relevant skills and attributes will continue where lifelong learning is understood only in general terms, or as a sub-set of generic, graduate attributes. It therefore recommends that some unpacking of the concept be undertaken, at the institutional level, and that possible assessment models and exemplars be provided for the different lifelong learning domains, including: self-awareness; self-management and judgement; self-efficacy and motivation; and relevant generic graduate skills such as research and/or information literacy, critical thinking and problem solving. (Contains 1 note.)