The clinical spectrum of the congenital myasthenic syndrome resulting from COL13A1 mutations.

Next generation sequencing techniques were recently used to show mutations in COL13A1 cause synaptic basal lamina-associated congenital myasthenic syndrome type 19. Animal studies showed COL13A1, a synaptic extracellular-matrix protein, is involved in the formation and maintenance of the neuromuscular synapse that appears independent of the Agrin-LRP4-MuSK-DOK7 acetylcholine receptor clustering pathway. Here, we report the phenotypic spectrum of 16 patients from 11 kinships harbouring homozygous or heteroallelic mutations in COL13A1. Clinical presentation was mostly at birth with hypotonia and breathing and feeding difficulties often requiring ventilation and artificial feeding. Respiratory crisis related to recurrent apnoeas, sometimes triggered by chest infections, were common early in life but resolved over time. The predominant pattern of muscle weakness included bilateral ptosis (non-fatigable in adulthood), myopathic facies and marked axial weakness, especially of neck flexion, while limb muscles were less involved. Other features included facial dysmorphism, skeletal abnormalities and mild learning difficulties. All patients tested had results consistent with abnormal neuromuscular transmission. Muscle biopsies were within normal limits or showed non-specific changes. Muscle MRI and serum creatine kinase levels were normal. In keeping with COL13A1 mutations affecting both synaptic structure and presynaptic function, treatment with 3,4-diaminopyridine and salbutamol resulted in motor and respiratory function improvement. In non-treated cases, disease severity and muscle strength improved gradually over time and several adults recovered normal muscle strength in the limbs. In summary, patients with COL13A1 mutations present mostly with severe early-onset myasthenic syndrome with feeding and breathing difficulties. Axial weakness is greater than limb weakness. Disease course improves gradually over time, which could be consistent with the less prominent role of COL13A1 once the neuromuscular junction is mature. This report emphasizes the role of collagens at the human muscle endplate and should facilitate the recognition of this disorder, which can benefit from pharmacological treatment.

Forecasting effects of transport infrastructure on endangered tigers: a tool for conservation planning.

The rapid development of transport infrastructure is a major threat to endangered species worldwide. Roads and railways can increase animal mortality, fragment habitats, and exacerbate other threats to biodiversity. Predictive models that forecast the future impacts to endangered species can guide land-use planning in ways that proactively reduce the negative effects of transport infrastructure. Agent-based models are well suited for predictive scenario testing, yet their application to endangered species conservation is rare. Here, we developed a spatially explicit, agent-based model to forecast the effects of transport infrastructure on an isolated tiger (Panthera tigris) population in Nepal's Chitwan National Park-a global biodiversity hotspot. Specifically, our model evaluated the independent and interactive effects of two mechanisms by which transport infrastructure may affect tigers: (a) increasing tiger mortality, e.g., via collisions with vehicles, and (b) depleting prey near infrastructure. We projected potential impacts on tiger population dynamics based on the: (i) existing transportation network in and near the park, and (ii) the inclusion of a proposed railway intersecting through the park's buffer zone. Our model predicted that existing roads would kill 46 tigers over 20 years via increased mortality, and reduced the adult tiger population by 39% (133 to 81). Adding the proposed railway directly killed 10 more tigers over those 20 years; deaths that reduced the overall tiger population by 30 more individuals (81 to 51). Road-induced mortality also decreased the proportion of time a tiger occupied a given site by 5 years in the 20-year simulation. Interestingly, we found that transportation-induced depletion of prey decreased tiger occupancy by nearly 20% in sites close to roads and the railway, thereby reducing tiger exposure to transportation-induced mortality. The results of our model constitute a strong argument for taking into account prey distributions into the planning of roads and railways. Our model can promote tiger-friendly transportation development, for example, by improving Environmental Impact Assessments, identifying "no go" zones where transport infrastructure should be prohibited, and recommending alternative placement of roads and railways.

De novo transcriptome assembly and analyses of gene expression during photomorphogenesis in diploid wheat Triticum monococcum.

BACKGROUND: Triticum monococcum (2n) is a close ancestor of T. urartu, the A-genome progenitor of cultivated hexaploid wheat, and is therefore a useful model for the study of components regulating photomorphogenesis in diploid wheat. In order to develop genetic and genomic resources for such a study, we constructed genome-wide transcriptomes of two Triticum monococcum subspecies, the wild winter wheat T. monococcum ssp. aegilopoides (accession G3116) and the domesticated spring wheat T. monococcum ssp. monococcum (accession DV92) by generating de novo assemblies of RNA-Seq data derived from both etiolated and green seedlings. PRINCIPAL FINDINGS: The de novo transcriptome assemblies of DV92 and G3116 represent 120,911 and 117,969 transcripts, respectively. We successfully mapped ∼90% of these transcripts from each accession to barley and ∼95% of the transcripts to T. urartu genomes. However, only ∼77% transcripts mapped to the annotated barley genes and ∼85% transcripts mapped to the annotated T. urartu genes. Differential gene expression analyses revealed 22% more light up-regulated and 35% more light down-regulated transcripts in the G3116 transcriptome compared to DV92. The DV92 and G3116 mRNA sequence reads aligned against the reference barley genome led to the identification of ∼500,000 single nucleotide polymorphism (SNP) and ∼22,000 simple sequence repeat (SSR) sites. CONCLUSIONS: De novo transcriptome assemblies of two accessions of the diploid wheat T. monococcum provide new empirical transcriptome references for improving Triticeae genome annotations, and insights into transcriptional programming during photomorphogenesis. The SNP and SSR sites identified in our analysis provide additional resources for the development of molecular markers.

Sequencing and de novo transcriptome assembly of Brachypodium sylvaticum (Poaceae).

PREMISE OF THE STUDY: We report the de novo assembly and characterization of the transcriptomes of Brachypodium sylvaticum (slender false-brome) accessions from native populations of Spain and Greece, and an invasive population west of Corvallis, Oregon, USA. • METHODS AND RESULTS: More than 350 million sequence reads from the mRNA libraries prepared from three B. sylvaticum genotypes were assembled into 120,091 (Corvallis), 104,950 (Spain), and 177,682 (Greece) transcript contigs. In comparison with the B. distachyon Bd21 reference genome and GenBank protein sequences, we estimate >90% exome coverage for B. sylvaticum. The transcripts were assigned Gene Ontology and InterPro annotations. Brachypodium sylvaticum sequence reads aligned against the Bd21 genome revealed 394,654 single-nucleotide polymorphisms (SNPs) and >20,000 simple sequence repeat (SSR) DNA sites. • CONCLUSIONS: To our knowledge, this is the first report of transcriptome sequencing of invasive plant species with a closely related sequenced reference genome. The sequences and identified SNP variant and SSR sites will provide tools for developing novel genetic markers for use in genotyping and characterization of invasive behavior of B. sylvaticum.