Single cell RNA-sequencing and RNA-tomography of the avian embryo extending body axis.

Introduction: Vertebrate body axis formation initiates during gastrulation and continues within the tail bud at the posterior end of the embryo. Major structures in the trunk are paired somites, which generate the musculoskeletal system, the spinal cord-forming part of the central nervous system, and the notochord, with important patterning functions. The specification of these different cell lineages by key signalling pathways and transcription factors is essential, however, a global map of cell types and expressed genes in the avian trunk is missing. Methods: Here we use high-throughput sequencing approaches to generate a molecular map of the emerging trunk and tailbud in the chick embryo. Results and Discussion: Single cell RNA-sequencing (scRNA-seq) identifies discrete cell lineages including somites, neural tube, neural crest, lateral plate mesoderm, ectoderm, endothelial and blood progenitors. In addition, RNA-seq of sequential tissue sections (RNA-tomography) provides a spatially resolved, genome-wide expression dataset for the avian tailbud and emerging body, comparable to other model systems. Combining the single cell and RNA-tomography datasets, we identify spatially restricted genes, focusing on somites and early myoblasts. Thus, this high-resolution transcriptome map incorporating cell types in the embryonic trunk can expose molecular pathways involved in body axis development.

Translating the Short-Form Headache Impact Test (HIT-6) in 27 countries: methodological and conceptual issues.

The process of translating the Short-Form Headache Impact Test (HIT-6) in 27 countries and the comparability of the content of the translations is discussed. HIT-6 translations were developed using a standard forward-backward translation process, including a cognitive debriefing step and international harmonization of the translations. Prior to translating the HIT-6, modifications were made to the English-language source form, to improve translation equivalence. In general, the HIT-6 was not difficult to translate. The most difficult items included colloquial expressions such as 'fed up' and words whose intended meaning changed in translation such as 'school' or 'lie down.' Subjects generally found the HIT-6 translations to be clear and relevant. The translation process resulted in questionnaires that are both culturally appropriate and comparable in content.