Chromosome-level genome assemblies of 2 hemichordates provide new insights into deuterostome origin and chromosome evolution.

Deuterostomes are a monophyletic group of animals that includes Hemichordata, Echinodermata (together called Ambulacraria), and Chordata. The diversity of deuterostome body plans has made it challenging to reconstruct their ancestral condition and to decipher the genetic changes that drove the diversification of deuterostome lineages. Here, we generate chromosome-level genome assemblies of 2 hemichordate species, Ptychodera flava and Schizocardium californicum, and use comparative genomic approaches to infer the chromosomal architecture of the deuterostome common ancestor and delineate lineage-specific chromosomal modifications. We show that hemichordate chromosomes (1N = 23) exhibit remarkable chromosome-scale macrosynteny when compared to other deuterostomes and can be derived from 24 deuterostome ancestral linkage groups (ALGs). These deuterostome ALGs in turn match previously inferred bilaterian ALGs, consistent with a relatively short transition from the last common bilaterian ancestor to the origin of deuterostomes. Based on this deuterostome ALG complement, we deduced chromosomal rearrangement events that occurred in different lineages. For example, a fusion-with-mixing event produced an Ambulacraria-specific ALG that subsequently split into 2 chromosomes in extant hemichordates, while this homologous ALG further fused with another chromosome in sea urchins. Orthologous genes distributed in these rearranged chromosomes are enriched for functions in various developmental processes. We found that the deeply conserved Hox clusters are located in highly rearranged chromosomes and that maintenance of the clusters are likely due to lower densities of transposable elements within the clusters. We also provide evidence that the deuterostome-specific pharyngeal gene cluster was established via the combination of 3 pre-assembled microsyntenic blocks. We suggest that since chromosomal rearrangement events and formation of new gene clusters may change the regulatory controls of developmental genes, these events may have contributed to the evolution of diverse body plans among deuterostomes.

Tracing the evolutionary origin of chordate somites in the hemichordate Ptychodera flava.

Metameric somites are a novel character of chordates with unclear evolutionary origins. In the early branching chordate amphioxus, anterior somites are derived from the paraxial mesodermal cells that bud off the archenteron (i.e., enterocoely) at the end of gastrulation. Development of the anterior somites requires FGF signaling, and distinct somite compartments express orthologs of vertebrate non-axial mesodermal markers. Thus, it has been proposed that the amphioxus anterior somites are homologous to the vertebrate head mesoderm, paraxial mesoderm and lateral plate mesoderm. To trace the evolutionary origin of somites, it is essential to study the chordates' closest sister group, Ambulacraria, which includes hemichordates and echinoderms. The anterior coeloms of hemichordate and sea urchin embryos (respectively called protocoel and coelomic pouches) are also formed by enterocoely and require FGF signals for specification and/or differentiation. In this study, we applied RNA-seq to comprehensively screen for regulatory genes associated with the mesoderm-derived protocoel of the hemichordate Ptychodera flava. We also used a candidate gene approach to identify P. flava orthologs of chordate somite markers. In situ hybridization results showed that many of these candidate genes are expressed in distinct or overlapping regions of the protocoel, which indicates that molecular compartments exist in the hemichordate anterior coelom. Given that the hemichordate protocoel and amphioxus anterior somites share a similar ontogenic process (enterocoely), induction signal (FGF), and characteristic expression of orthologous genes, we propose that these two anterior coeloms are indeed homologous. In the lineage leading to the emergence of chordates, somites likely evolved from enterocoelic, FGF-dependent, and molecularly compartmentalized anterior coeloms of the deuterostome last common ancestor.

Gain of gene regulatory network interconnectivity at the origin of vertebrates.

SignificanceIn this manuscript, we address an essential question in developmental and evolutionary biology: How have changes in gene regulatory networks contributed to the invertebrate-to-vertebrate transition? To address this issue, we perturbed four signaling pathways critical for body plan formation in the cephalochordate amphioxus and in zebrafish and compared the effects of such perturbations on gene expression and gene regulation in both species. Our data reveal that many developmental genes have gained response to these signaling pathways in the vertebrate lineage. Moreover, we show that the interconnectivity between these pathways is much higher in zebrafish than in amphioxus. We conclude that this increased signaling pathway complexity likely contributed to vertebrate morphological novelties during evolution.

The perception of crowding, quality and well-being: a study of Vietnamese public health services.

PURPOSE: The purpose of this paper is to examine the extent to which the perception of crowding by medical staff and patients impacts patients' perceived service quality (SQ), overall satisfaction and emotional well-being. DESIGN/METHODOLOGY/APPROACH: Data were collected from 258 matched pairs of medical staff members and their patients at six public hospitals. FINDINGS: Medical staff-perceived crowding negatively influences patients' perceived SQ. The perceived SQ then impacts patients' overall satisfaction and emotional well-being. Patients' perceived crowding does not significantly impact their perceived SQ but increases the positive emotional well-being of patients. ORIGINALITY/VALUE: Scant research has investigated a matched pair of service providers and their customers. This study concentrates on how individuals' perceived human crowding and medical staff SQ affect consumers' emotional well-being. This research leads to the formulation of theoretical and public policy suggestions to improve the quality of interactive services with minimal cost and disruption.

The Perceptions of Physicians and Nurses Regarding the Establishment of Patient Safety in a Regional Teaching Hospital in Taiwan.

BACKGROUND: Physicians and nurses are core staff who are the first points of contact in care provision to patients. We aimed to examine physicians' and nurses' perceptions of patient safety in a case hospital by administering the Chinese Safety Attitude Questionnaire (CSAQ), developed from the Taiwan Joint Commission on Hospital Accreditation, in order to provide the patients with a safe environment and excellent medical service. METHODS: An intra-organizational online survey was conducted. Confirmatory factor analysis (CFA) was first performed on the assessment of the measures for patient safety culture and seven dimensions with 33 items were identified. Pearson correlation analysis was subsequently used to examine the strength and direction of the relationships between seven dimensions of patient safety culture. RESULTS: A total of 800 questionnaires were issued and 405 valid questionnaires were collected, the effective response rate being 50.6%. The findings highlighted that safety climate (SC) was positively and significantly related to teamwork climate (TC) and perception of management (PM), whereas stress recognition (SR) was negatively related to burnout (BUR). CONCLUSION: Patient safety culture in healthcare organizations has been considered a critical issue for improving the quality of healthcare. This study further focused on the contribution of a better patient safety culture for healthcare organizations in Taiwan.