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.

Discriminating factors of body composition characteristics for academic performance in nursing college students: a cross-sectional study.

BACKGROUND: Poor body composition may affect health status, and better body composition is often associated with better academic performance. Nursing students face heavy academic and practical pressures, and the relationship between body composition and academic performance in this group is not fully understood. METHODS: This cross-sectional observational study used de-identified student data from a university of technology in southern Taiwan to analyze the correlation between body composition characteristics and academic performance using regression models. RESULTS: A total of 275 nursing college students were divided into four groups according to academic performance. The group with the lowest academic performance had a lower percentage of body fat (P < 0.05) but a higher percentage of muscle mass (P < 0.05) than the other three groups. Academic performance was positively correlated with percentage of body fat (R = 0.16, P < 0.01) and body age (R = 0.41, P < 0.01), but was negatively correlated with percentage of muscle mass (R = - 0.16, P < 0.01). Percentage of body fat, visceral fat area, and body age were significant discriminators of academic performance (P < 0.05). CONCLUSIONS: The relationship between academic performance and body composition among nursing college students is not straightforward. Contrary to our initial hypothesis, students with higher academic performance tended to have a higher percentage of body fat and a lower percentage of muscle mass. Percentage of body fat, visceral fat area, and body age were significant discriminators of academic performance, indicating that body composition should be considered an important factor in nursing education and practice.

BMP controls dorsoventral and neural patterning in indirect-developing hemichordates providing insight into a possible origin of chordates.

A defining feature of chordates is the unique presence of a dorsal hollow neural tube that forms by internalization of the ectodermal neural plate specified via inhibition of BMP signaling during gastrulation. While BMP controls dorsoventral (DV) patterning across diverse bilaterians, the BMP-active side is ventral in chordates and dorsal in many other bilaterians. How this phylum-specific DV inversion occurs and whether it is coupled to the emergence of the dorsal neural plate are unknown. Here we explore these questions by investigating an indirect-developing enteropneust from the hemichordate phylum, which together with echinoderms form a sister group of the chordates. We found that in the hemichordate larva, BMP signaling is required for DV patterning and is sufficient to repress neurogenesis. We also found that transient overactivation of BMP signaling during gastrulation concomitantly blocked mouth formation and centralized the nervous system to the ventral ectoderm in both hemichordate and sea urchin larvae. Moreover, this mouthless, neurogenic ventral ectoderm displayed a medial-to-lateral organization similar to that of the chordate neural plate. Thus, indirect-developing deuterostomes use BMP signaling in DV and neural patterning, and an elevated BMP level during gastrulation drives pronounced morphological changes reminiscent of a DV inversion. These findings provide a mechanistic basis to support the hypothesis that an inverse chordate body plan emerged from an indirect-developing ancestor by tinkering with BMP signaling.

Targeting of Mcl-1 Expression by MiRNA-3614-5p Promotes Cell Apoptosis of Human Prostate Cancer Cells.

MicroRNA (miRNA) acts as a critical regulator of growth in various human malignancies. However, the role of miRNA-3614 in the progression of human prostate cancer remains unknown. In this study, our results demonstrated that miRNA-3614-5p exerts a significant inhibitory effect on cell viability and colony formation and induces sub-G1 cell cycle arrest and apoptosis in human prostate cancer cells. Myeloid cell leukemia-1 (Mcl-1) acts as a master regulator of cell survival. Using the miRNA databases, miRNA-3614-5p was found to regulate Mcl-1 expression by targeting positions of the Mcl-1-3' UTR. The reduction of Mcl-1 expression by miRNA-3614-5p was further confirmed using an immunoblotting assay. Pro-apoptotic caspase-3 and poly (ADP-ribose) polymerase (PARP) were significantly activated by miRNA-3614-5p to generate cleaved caspase-3 (active caspase-3) and cleaved PARP (active PARP), accompanied by the inhibited Mcl-1 expression. These findings were the first to demonstrate the anti-growth effects of miRNA-3614-5p through downregulating Mcl-1 expression in human prostate cancer cells.

Evidence for BMP-mediated specification of primordial germ cells in an indirect-developing hemichordate.

Primordial germ cells (PGCs) are specified during development by either one of two major mechanisms, the preformation mode or the inductive mode. Because the inductive mode is widely employed by many bilaterians and early branching metazoan lineages, it has been postulated as an ancestral mechanism. However, among the deuterostome species that have been studied, invertebrate chordates use the preformation mode, while many vertebrate and echinoderm species are known to utilize an inductive mechanism, thus leaving the evolutionary history of PGC specification in the deuterostome lineage unclear. Hemichordates are the sister phylum of echinoderms, and together they form a clade called Ambulacraria that represents the closest group to the chordates. Thus, research in hemichordates is highly informative for resolving this issue. In this study, we investigate the developmental process of PGCs in an indirect-developing hemichordate, Ptychodera flava. We show that maternal transcripts of the conserved germline markers vasa, nanos, and piwi1 are ubiquitously distributed in early P. flava embryos, and these genes are coexpressed specifically in the dorsal hindgut starting from the gastrula stage. Immunostaining revealed that Vasa protein is concentrated toward the vegetal pole in early P. flava embryos, and it is restricted to cells in the dorsal hindgut of gastrulae and newly hatched larvae. The Vasa-positive cells later contribute to the developing trunk coeloms of the larvae and eventually reside in the adult gonads. We further show that bone morphogenetic protein (BMP) signaling is required to activate expression of the germline determinants in the gastrula hindgut, suggesting that PGC specification is induced by BMP signaling in P. flava. Our data support the hypothesis that the inductive mode is a conserved mechanism in Ambulacraria, which might even trace back to the common ancestor of Deuterostomes.

Norcantharidin combined with paclitaxel induces endoplasmic reticulum stress mediated apoptotic effect in prostate cancer cells by targeting SIRT7 expression.

Prostate cancer (PCa), an extremely common malignancy in males, is the most prevalent disease in several countries. Norcantharidin (NCTD) has antiproliferation, antimetastasis, apoptosis, and autophagy effects in various tumor cells. Nevertheless, the antitumor effect of NCTD combined with paclitaxel (PTX), a chemotherapeutic drug, in PCa remains unknown. The cell growth, proliferative rate, cell cycle distribution, and cell death were determined by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide, colony formation assay, PI staining, and Annexin V/PI staining by flow cytomertry, whereas the mitochondrial membrane potential (MMP) and endoplasmic reticulum (ER) stress was evaluated using the MitoPotential assay and ER-ID red assay. We also evaluated the protein and mRNA expression of SIRTs by Western blotting and qRTPCR assay. Overexpression effectivity was measured by DNA transfection assay. Our study showed that cell viability and proliferative PC3 and DU145 rates were effectively inhibited after NCTD-PTX combination. We also found that NCTD-PTX combination treatment significantly enhance G2/M phase arrest, induction of cell death and ER stress, loss of MMP, and ER- or apoptotic-related protein expression. Furthermore, NCTD-PTX combination treatment was significantly decreasing the protein and mRNA expression of SIRT7 in PCa cells. Combination therapy effectively reduced cell viability, ER stress-mediated apoptosis and p-eIF2α/ATF4/CHOP/cleaved-PARP expression inhibition in SIRT7 overexpression of PCa cells. These results indicate that NCTD combined with PTX induces ER stress-mediated apoptosis of PCa cells by regulating the SIRT7 expression axis. Moreover, combination therapy may become a potential therapeutic strategy against human PCa.

Neuron-Specific HuR-Deficient Mice Spontaneously Develop Motor Neuron Disease.

Human Ag R (HuR) is an RNA binding protein in the ELAVL protein family. To study the neuron-specific function of HuR, we generated inducible, neuron-specific HuR-deficient mice of both sexes. After tamoxifen-induced deletion of HuR, these mice developed a phenotype consisting of poor balance, decreased movement, and decreased strength. They performed significantly worse on the rotarod test compared with littermate control mice, indicating coordination deficiency. Using the grip-strength test, it was also determined that the forelimbs of neuron-specific HuR-deficient mice were much weaker than littermate control mice. Immunostaining of the brain and cervical spinal cord showed that HuR-deficient neurons had increased levels of cleaved caspase-3, a hallmark of cell apoptosis. Caspase-3 cleavage was especially strong in pyramidal neurons and α motor neurons of HuR-deficient mice. Genome-wide microarray and real-time PCR analysis further indicated that HuR deficiency in neurons resulted in altered expression of genes in the brain involved in cell growth, including trichoplein keratin filament-binding protein, Cdkn2c, G-protein signaling modulator 2, immediate early response 2, superoxide dismutase 1, and Bcl2. The additional enriched Gene Ontology terms in the brain tissues of neuron-specific HuR-deficient mice were largely related to inflammation, including IFN-induced genes and complement components. Importantly, some of these HuR-regulated genes were also significantly altered in the brain and spinal cord of patients with amyotrophic lateral sclerosis. Additionally, neuronal HuR deficiency resulted in the redistribution of TDP43 to cytosolic granules, which has been linked to motor neuron disease. Taken together, we propose that this neuron-specific HuR-deficient mouse strain can potentially be used as a motor neuron disease model.

Impact of periodontal disease and chewing ability on the quality of life of the elderly in an affluent community.

BACKGROUND/PURPOSE: Improvement of the medical and social environment is an important aspect of government policies in assuring the quality of life (QoL) of older adults. However, few studies have appraised the impact and relationship of QoL with clinical factors among elderly individuals in affluent residential areas. METHODS: A total of 166 older adults from Chang Gung Health and Culture Village were enrolled. Oral health-related QoL was measured using the Geriatric Oral Health Assessment Index. Self-assessed chewing abilities and demographic characteristics were collected by questionnaire. Physical health was scored by activities of daily living (ADL) and instrumental ADL. Mini nutrition assessment questionnaire was used to evaluate the nutritional intake. Multiple linear regression was used to predict risk factors affecting QoL and to examine whether chewing ability was a mediator of oral health-related QoL. RESULTS: Poor chewing ability was associated with older age (OR = 1.82 for 76-85 years and 3.58 for 86-95 years), sufficient economic status (OR = 5.55) and removable denture-wearing (OR = 7.52). On the other hand, poor chewing ability (OR = 0.11), removable denture-wearing (OR = 0.48), periodontal disease (OR = 0.38) had lower likelihood of good oral health-related QoL. Mediator analyses showed that chewing ability was a mediator for the association between oral health-related QoL and economic status or removable denture-wearing or having more than 20 teeth. Periodontal disease was an independent factor for oral health-related QoL. CONCLUSION: Among older adults in an affluent community, periodontal disease is an independent risk factor directly related to oral health-related QoL, whereas chewing ability is a mediator between QoL and removable denture-wearing.

Verification and Evaluation of a Visual Reaction System for Badminton Training.

The two aims of this study were (1) designing and developing an affordable visual reaction system for badminton training that monitors and provides instant feedback on agility; and (2) to measure and improve the footwork and movement of badminton players and output useful reference data. Ten junior high school badminton players were invited to serve as the subjects of this study. They participated in a three-week (nine sessions) training program. Training was primarily in the form of fixed or random footwork drills. Timed tests were performed before and after each session to measure the players' agility in performing six-point and four-point footwork drills. The results were compared to the training effects calculated using dependent-sample t-tests. In addition, the long-term durability and functionality of the training system were tested. The training system was able to maintain stable and reliable training and evaluation operations for extended periods. Results showed significant improvements in the visual reaction time (p = 0.003) and agility (p = 0.001) of players. The proposed training system is an affordable option for training and monitoring, evaluating, and recording training performance. It can accurately record movement and response times and simulate competitive environments.

Changes in drowning mortality rates and quality of reporting from 2004-2005 to 2014-2015: a comparative study of 61 countries.

BACKGROUND: This study assessed international variations in changes in drowning mortality rates and the quality of reporting specific information in death certificates over the past decade. METHODS: Drowning mortality data of 61 countries were extracted from the World Health Organization Mortality Database. We calculated the percentage change (PC) in age-standardized drowning mortality rates and percentage of drowning deaths reported with unspecified codes between 2004 and 2005 and 2014-2015. RESULTS: Of the 61 countries studied, 50 exhibited a reduction in drowning mortality rates from 2004 to 2005 to 2014-2015. Additionally, five countries-Lithuania, Moldova, Kyrgyzstan, Romania, and El Salvador-with a high mortality rate in 2004-2005 (> 40 deaths per 100,000) showed improvement (PC < - 32%). By contrast, four countries-South Africa, Guyana, Morocco, and Guatemala-exhibited a more than twofold increase in mortality rates. Regarding the quality of reporting, 34 countries exhibited a decrease in the percentage of unspecified codes. Additionally, three countries-Paraguay, Serbia, and Croatia-with moderate and high percentages of unspecified codes (> 40%) exhibited a marked reduction (PC < - 60%), whereas three countries-Malaysia, Belgium, and Nicaragua-exhibited a notable increase. CONCLUSIONS: Large international variations in the extent of changes in drowning mortality rates and the quality of reporting specific information on the death certificate were observed during the study period.

Synergistic antimetastatic effect of cotreatment with licochalcone A and sorafenib on human hepatocellular carcinoma cells through the inactivation of MKK4/JNK and uPA expression.

To improve the clinical outcome of tumor chemotherapy, more effective combination treatments against tumor metastasis and recurrence are required. Licochalcone A (LicA) is the root of Glycyrrhiza inflata and has been reported to possess anti-inflammatory, antimicrobial, and antitumor effects. Sorafenib (Sor), a multikinase inhibitor, is used to treat patients with solid tumors such as advanced hepatocellular carcinoma (HCC). However, the synergistic effects of LicA and Sor on the metastasis of human HCC cells have not been reported. We found that LicA and Sor did not have cytotoxic effects or arrest growth in human SK-Hep-1 and Huh-7 cells. In addition, treatment with LicA or Sor alone inhibited migration and invasion in human SK-Hep-1 and Huh-7 HCC cells. Furthermore, cotreatment with LicA and Sor synergistically inhibited the migration and invasion of HCC cells and significantly inhibited uPA protein expression. Notably, cotreatment of LicA and Sor synergistically and significantly downregulated MKK4-JNK expression. Through tail vein injection in nude mice, the aforementioned cotreatment synergistically suppressed SK-Hep-1 cell-mediated lung metastasis. These findings first revealed the synergistic effects of LicA and Sor cotreatment against human HCC cells, further suggesting that beneficial effects on tumor regression could be confirmed through prospective clinical trials.

Praeruptorin A Inhibits Human Cervical Cancer Cell Growth and Invasion by Suppressing MMP-2 Expression and ERK1/2 Signaling.

Praeruptorin A (PA) is a pyranocumarin present in the dried root of Peucedanumpraeruptorum Dunn that has anticancer effects against several types of cells. However, the effect of PA on human cervical cancer cells is unknown. Our results indicate that PA significantly inhibited cell proliferation, colony formation, migration, invasion, and wound closure of HeLa and SiHa cells, induced cell cycle arrest at G0/G1 phase, upregulated Rb, p16, p21 and p27 proteins and downregulated cyclin D1 and S-phase kinase-associated protein 2 (Skp2) proteins. PA also significantly reduced expression of matrix metalloproteinase-2 (MMP-2) and increased expression of tissue inhibitor of metalloproteinase-2 (TIMP-2). In addition, PA suppressed ERK1/2 activation and increased the effect of PD98059 (a specific MEK1/2 inhibitor) in downregulation of MMP-2 and upregulation of TIMP-2. PA treatment inhibited the effect of 12-O-tetradecanoylphorbol-13-acetate (TPA) on upregulation of ERK1/2 activation, MMP-2 expression, cellular migration, and invasion of HeLa cells. Our findings are the first to demonstrate the activity of PA against cervical cancer cells, and suggest this agent has promise as a therapeutic agent in treatment of human cervical cancer.

Reproductive periodicity, spawning induction, and larval metamorphosis of the hemichordate acorn worm Ptychodera flava.

The indirect-developing enteropneust acorn worm Ptychodera flava has been used as a hemichordate model system for studying the developmental evolution of deuterostome body plans and the origins of chordate characteristics. However, research progress has been hindered by the limited accessibility of its embryonic materials and metamorphosing larvae. In this study, we identified an abundant population of P. flava in Penghu, Taiwan, and examined the feasibility of using this animal for developmental studies. Through histological examination, we established that the reproductive season of this population is between September and December, with a peak breeding period in October and November. In addition, we have developed new procedures that can induce P. flava spawning at any time of the day during the breeding season, with a higher successful rate than that achieved using a previously published method. Moreover, the culturing system we developed enables rearing of P. flava larvae through various planktonic stages and eventual metamorphosis into benthic juveniles, all under laboratory conditions. We anticipate that the animal resources and new technical procedures reported here will further facilitate the use of P. flava as a model organism for evolutionary and developmental biology research.

Prenatal exposure to phthalate ester and pubertal development in a birth cohort in central Taiwan: a 12-year follow-up study.

Phthalate esters are widely used plasticizers that are present in many daily used products. Although some of their reproductive effects have been reported, pubertal development effects from prenatal exposure to phthalates awaits further investigations. A population based birth cohort was established (N=437 at baseline) with maternal exposure to phthalates assessed in urine collected at the third trimester of pregnancy in 2001 and 2002. Their 133 children with prenatal phthalates exposure were followed up for the outcomes of pubertal development by sequential physical examinations at eight and 11 years old in 2009 and 2012. Urinary concentrations of major phthalate metabolites (i.e., mono-2-ethylhexyl phthalate [MEHP], mono-(2-ethyl-5-hydroxyhexyl) phthalate [MEHHP], mono-(2-ethyl-5-oxohexyl) phthalate [MEOHP], mono-butyl phthalate [MBP], mono-benzyl phthalate [MBzP], monomethyl phthalate [MMP], and mono-ethyl phthalate [MEP]) were determined using liquid chromatography linked to tandem mass spectrometry. The reproductive development measurements included bone age (for both genders), testicle size (for boys), uterus size, and ovarian volume (for girls). We reported results of 133 children with complete data by applying generalized estimating equations for the repeated continuous outcomes. After controlling for Tanner stage, we detected a significant association between reduced uterus size and increasing phthalate exposure in the 2(nd) tertile relative to the 1st tertile of creatinine-corrected MEHP (B=-0.40; 95% C.I.: -0.73, -0.07, relative to the 1st tertile) and total DEHP (B=-0.39, 95% C.I.:-0.66, -0.01 for the 2nd tertile and B=0.34, 95% C.I.: -0.67, -0.01 for the 3rd tertile, relative to the 1st tertile) with a linear trend among girls. MBzP was also found negatively associated with bone age/chronological age ratio (B=-0.07, 95% CI: -0.13, -0.01 for the 3rd tertile, relative to the 1st tertile) with a linear trend for girls. We found no evidence of an association between phthalate exposure and ovarian volume or testicle size. This analysis suggests phthalate exposure may affect specific pubertal development characteristics in human beings. Further studies with larger sample sizes and longer follow-up period are warranted.

Nerve regeneration restores supraspinal control of bladder function after complete spinal cord injury.

A life-threatening disability after complete spinal cord injury is urinary dysfunction, which is attributable to lack of regeneration of supraspinal pathways that control the bladder. Although numerous strategies have been proposed that can promote the regrowth of severed axons in the adult CNS, at present, the approaches by which this can be accomplished after complete cord transection are quite limited. In the present study, we modified a classic peripheral nerve grafting technique with the use of chondroitinase to facilitate the regeneration of axons across and beyond an extensive thoracic spinal cord transection lesion in adult rats. The novel combination treatment allows for remarkably lengthy regeneration of certain subtypes of brainstem and propriospinal axons across the injury site and is followed by markedly improved urinary function. Our studies provide evidence that an enhanced nerve grafting strategy represents a potential regenerative treatment after severe spinal cord injury.

The Spatiotemporal Expression of SOCS3 in the Brainstem and Spinal Cord of Amyotrophic Lateral Sclerosis Mice.

Amyotrophic lateral sclerosis (ALS) is characterized by the progressive loss of motor neurons from the brain and spinal cord. The excessive neuroinflammation is thought to be a common determinant of ALS. Suppressor of cytokine signaling-3 (SOCS3) is pathologically upregulated after injury/diseases to negatively regulate a broad range of cytokines/chemokines that mediate inflammation; however, the role that SOCS3 plays in ALS pathogenesis has not been explored. Here, we found that SOCS3 protein levels were significantly increased in the brainstem of the superoxide dismutase 1 (SOD1)-G93A ALS mice, which is negatively related to a progressive decline in motor function from the pre-symptomatic to the early symptomatic stage. Moreover, SOCS3 levels in both cervical and lumbar spinal cords of ALS mice were also significantly upregulated at the pre-symptomatic stage and became exacerbated at the early symptomatic stage. Concomitantly, astrocytes and microglia/macrophages were progressively increased and reactivated over time. In contrast, neurons were simultaneously lost in the brainstem and spinal cord examined over the course of disease progression. Collectively, SOCS3 was first found to be upregulated during ALS progression to directly relate to both increased astrogliosis and increased neuronal loss, indicating that SOCS3 could be explored to be as a potential therapeutic target of ALS.

Efficacy and Safety of Ginger on Chemotherapy-Induced Nausea and Vomiting: A Systematic Review and Meta-analysis of Randomized Controlled Trials.

BACKGROUND: Chemotherapy-induced nausea and vomiting (CINV) is a prevalent and distressing side effect. Historically, ginger has been explored as a potential remedy for various ailments, including its potential efficacy against CINV. OBJECTIVE: The aim of this study was to determine whether taking ginger supplements can relieve CINV. METHOD: A comprehensive search was conducted across PubMed, EMBASE, Cochrane Library, and the Wanfang database. Randomized controlled trials meeting our inclusion criteria were analyzed. The primary outcomes were the incidence and severity of CINV. The protocol was registered on PROSPERO, and the number is CRD4202232104. RESULT: Of the 35 randomized controlled trials analyzed, 22 trials employed ginger capsules as the primary intervention, whereas 13 studies evaluated the prophylactic effects of ginger-partitioned moxibustion. The outcomes indicated that combining ginger capsules with standard antiemetic agents can significantly reduce the incidence of grade 3 acute nausea (Risk Ratio [RR], 0.19; P < .001) and the incidence of high-grade overall vomiting (RR, 0.47; P = .01). Moreover, ginger-partitioned moxibustion can significantly alleviate the incidence of both mild (RR, 0.56; P = .001) and severe (RR, 0.39; P < .00001) vomiting. Only 2.8% of patients experienced dizziness after ginger-partitioned moxibustion. CONCLUSIONS: Our findings indicate that ginger capsules, when used alongside antiemetic drugs, enhance the management of severe CINV, particularly in highly emetogenic chemotherapy regimens. IMPLICATIONS FOR PRACTICE: Based on our findings, we recommend initiating ginger supplements before chemotherapy, in conjunction with standard antiemetics, to reduce the severity of CINV. The promising results warrant more rigorous clinical trials to firmly establish the role of ginger in CINV management.

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.

Embryonic and post-embryonic development in the parasitic copepod Ive ptychoderae (Copepoda: Iviidae): Insights into its phylogenetic position.

Parasitic copepods are frequently discovered in many marine animals, and they exhibit great species diversity with remarkable morphological adaptations to their parasitic lifestyle. Similar to their free-living relatives, parasitic copepods usually develop through complex life cycle, but they eventually transform into a modified adult form with reduced appendages. Although the life cycle and distinct larval stages have been described in a few species of parasitic copepods, particularly those infecting commercially valuable marine animals (such as fishes, oysters, and lobsters), very little is known about the developmental process of the species that transformed into extremely simplified adult body plan. This paucity also causes some difficulties when investigating the taxonomy and phylogeny of this kind of parasitic copepods. Here we describe the embryonic development and a series of sequential larval stages of a parasitic copepod, Ive ptychoderae, which is a vermiform endoparasite living inside the hemichordate acorn worms. We devised laboratory regimes that enable us raising large quantity of embryos and free living larvae, and obtaining post-infested I. ptychoderae samples from the host tissues. Using defined morphological features, the embryonic development of I. ptychoderae can be categorized into eight stages (1-, 2-, 4-, 8-, 16- cell stages, blastula, gastrula, and limb bud stages) and the post-embryonic development comprises six larval stages (2 naupliar and 4 copepodid stages). Based on the comparisons of morphological characters in the nauplius stage, our results provide evidence to support that the Ive-group is more closely related to the Cyclopoida, which represents one of the two major clades that contain many highly transformed parasitic copepods. Thus, our results help to resolve the problematic phylogenetic position of the Ive-group in previous study based on analysis using 18S rDNA sequences. Combining with more molecular data, future comparative analyses on the morphological features of copepodid stages will further refine our understanding of the phylogenetic relationships of parasitic copepods.