Genome organization of the vg1 and nodal3 gene clusters in the allotetraploid frog Xenopus laevis.

Extracellular factors belonging to the TGF-β family play pivotal roles in the formation and patterning of germ layers during early Xenopus embryogenesis. Here, we show that the vg1 and nodal3 genes of Xenopus laevis are present in gene clusters on chromosomes XLA1L and XLA3L, respectively, and that both gene clusters have been completely lost from the syntenic S chromosome regions. The presence of gene clusters and chromosome-specific gene loss were confirmed by cDNA FISH analyses. Sequence and expression analyses revealed that paralogous genes in the vg1 and nodal3 clusters on the L chromosomes were also altered compared to their Xenopus tropicalis orthologs. X. laevis vg1 and nodal3 paralogs have potentially become pseudogenes or sub-functionalized genes and are expressed at different levels. As X. tropicalis has a single vg1 gene on chromosome XTR1, the ancestral vg1 gene in X. laevis appears to have been expanded on XLA1L. Of note, two reported vg1 genes, vg1(S20) and vg1(P20), reside in the cluster on XLA1L. The nodal3 gene cluster is also present on X. tropicalis chromosome XTR3, but phylogenetic analysis indicates that nodal3 genes in X. laevis and X. tropicalis were independently expanded and/or evolved in concert within each cluster by gene conversion. These findings provide insights into the function and molecular evolution of TGF-β family genes in response to allotetraploidization

Histological diagnostic criterion for chronic endometritis based on the clinical outcome.

Background:The diagnostic criteria of chronic endometritis remain controversial in the treatment for infertile patients.Methods: A prospective observational study was conducted in a single university from June 2014 to September 2017. Patients who underwent single frozen-thawed blastocyst transfer with a hormone replacement cycle after histological examination for the presence of chronic endometritis were enrolled. Four criteria were used to define chronic endometritis according to the number of plasma cells in the same group of patients: 1 or more (≥ 1) plasma cells, 2 or more (≥ 2), 3 or more (≥ 3), or 5 or more (≥ 5) in 10 high-power fields. Pregnancy rates, live birth rates, and miscarriage rates of the non-chronic endometritis and the chronic endometritis groups defined with each criterion were calculated. A logistic regression analysis was performed for live births using eight explanatory variables (seven infertility factors and chronic endometritis). A receiver operating characteristic curve was drawn and the optimal cut-off value was calculated.Results:A total of 69 patients were registered and 53 patients were finally analyzed after exclusion. When the diagnostic criterion was designated as the presence of ≥ 1 plasma cell in the endometrial stroma per 10 high-power fields, the pregnancy rate, live birth rate, and miscarriage rate were 63.0% vs. 30.8%, 51.9% vs. 7.7%, and 17.7% vs. 75% in the non-chronic and chronic endometritis groups, respectively. This criterion resulted in the highest pregnancy and live birth rates among the non-chronic endometritis and the smallest P values for the pregnancy rates, live birth rates, and miscarriage rates between the non-chronic and chronic endometritis groups. In the logistic regression analysis, chronic endometritis was an explanatory variable negatively affecting the objective variable of live birth only when chronic endometritis was diagnosed with ≥ 1 or ≥ 2 plasma cells per 10 high-power fields. The optimal cut-off value was obtained when one or more plasma cells were found in 10 high-power fields (sensitivity 87.5%, specificity 64.9%).Conclusions:Chronic endometritis should be diagnosed as the presence of ≥ 1 plasma cells in 10 high-power fields. According to this diagnostic criterion, chronic endometritis adversely affected the pregnancy rate and the live birth rate

Purkinje Fibers of the Avian Heart Express a Myogenic Transcription Factor Program Distinct from Cardiac and Skeletal Muscle

AbstractA rhythmic heart beat is coordinated by conduction of pacemaking impulses through the cardiac conduction system. Cells of the conduction system, including Purkinje fibers, terminally differentiate from a subset of cardiac muscle cells that respond to signals from endocardial and coronary arterial cells. A vessel-associated paracrine factor, endothelin, can induce embryonic heart muscle cells to differentiate into Purkinje fibers both in vivo and in vitro. During this phenotypic conversion, the conduction cells down-regulate genes characteristic of cardiac muscle and up-regulate subsets of genes typical of both skeletal muscle and neuronal cells. In the present study, we examined the expression of myogenic transcription factors associated with the switch of the gene expression program during terminal differentiation of heart muscle cells into Purkinje fibers. In situ hybridization analyses and immunohistochemistry of embryonic and adult hearts revealed that Purkinje fibers up-regulate skeletal and atrial muscle myosin heavy chains, connexin-42, and neurofilament protein. Concurrently, a cardiac muscle-specific myofibrillar protein, myosin-binding protein-C (cMyBP-C), is down-regulated. During this change in transcription, however, Purkinje fibers continue to express cardiac muscle transcription factors, such as Nkx2.5, GATA4, and MEF2C. Importantly, significantly higher levels of Nkx2.5 and GATA4 mRNAs were detected in Purkinje fibers as compared to ordinary heart muscle cells. No detectable difference was observed in MEF2C expression. In culture, endothelin-induced Purkinje fibers from embryonic cardiac muscle cells dramatically down-regulated cMyBP-C transcription, whereas expression of Nkx2.5 and GATA4 persisted. In addition, myoD, a skeletal muscle transcription factor, was up-regulated in endothelin-induced Purkinje cells, while Myf5 and MRF4 transcripts were undetectable in these cells. These results show that during and after conversion from heart muscle cells, Purkinje fibers express a unique myogenic transcription factor program. The mechanism underlying down-regulation of cardiac muscle genes and up-regulation of skeletal muscle genes during conduction cell differentiation may be independent from the transcriptional control seen in ordinary cardiac and skeletal muscle cells

The forkhead transcription factor FoxB1 regulates the dorsal–ventral and anterior–posterior patterning of the ectoderm during early Xenopus embryogenesis

AbstractThe formation of the dorsal–ventral (DV) and anterior–posterior (AP) axes, fundamental to the body plan of animals, is regulated by several groups of polypeptide growth factors including the TGF-β, FGF, and Wnt families. In order to ensure the establishment of the body plan, the processes of DV and AP axis formation must be linked and coordinately regulated. However, the molecular mechanisms responsible for these interactions remain unclear. Here, we demonstrate that the forkhead box transcription factor FoxB1, which is upregulated by the neuralizing factor Oct-25, plays an important role in the formation of the DV and AP axes. Overexpression of FoxB1 promoted neural induction and inhibited BMP-dependent epidermal differentiation in ectodermal explants, thereby regulating the DV patterning of the ectoderm. In addition, FoxB1 was also found to promote the formation of posterior neural tissue in both ectodermal explants and whole embryos, suggesting its involvement in embryonic AP patterning. Using knockdown analysis, we found that FoxB1 is required for the formation of posterior neural tissues, acting in concert with the Wnt and FGF pathways. Consistent with this, FoxB1 suppressed the formation of anterior structures via a process requiring the function of XWnt-8 and eFGF. Interestingly, while downregulation of FoxB1 had little effect on neural induction, we found that it functionally interacted with its upstream factor Oct-25 and plays a supportive role in the induction and/or maintenance of neural tissue. Our results suggest that FoxB1 is part of a mechanism that fine-tunes, and leads to the coordinated formation of, the DV and AP axes during early development

Induction and patterning of the Purkinje fiber network

Our studies in the embryonic chick heart have shown that impulse-conducting Purkinje cells differentiate from myocytes during embryogenesis. This conversion of contractile myocytes into conduction cells is induced by paracrine signals, such as endothelin (ET), derived from the endocardium and developing coronary arteries. Active ET is secreted through proteolytic processing from its precursor by ET-converting enzyme-1 (ECE-1) and triggers signaling by binding to its receptors. In the embryonic heart, two ET receptors, ETA and ETB, are expressed by myocytes. ECE-1 is predominantly expressed in endothelial cells of the endocardium and coronary arteries, but not in veins or capillaries. Furthermore, retroviral co-expression of exogenous ECE-1 with ET precursor in the embryonic heart is sufficient to induce ectopic myocyte conversion to conduction cells. Thus, localized expression of ECE-1 in endocardial and arterial endothelia is a key mechanism defining the site of Purkinje fiber recruitment in the embryonic myocardium. Inhibition of endogenous ECE-1 expression via suppression of stretch-sensitive channels results in down-regulated expression of Purkinje fiber markers. This finding suggests that biophyical forces acted on, and created by, the cardiovascular system during embryogenesis may play a critical role in induction and patterning of Purkinje fibers

Genome organization of the vg1 and nodal3 gene clusters in the allotetraploid frog Xenopus laevis.

Extracellular factors belonging to the TGF-β family play pivotal roles in the formation and patterning of germ layers during early Xenopus embryogenesis. Here, we show that the vg1 and nodal3 genes of Xenopus laevis are present in gene clusters on chromosomes XLA1L and XLA3L, respectively, and that both gene clusters have been completely lost from the syntenic S chromosome regions. The presence of gene clusters and chromosome-specific gene loss were confirmed by cDNA FISH analyses. Sequence and expression analyses revealed that paralogous genes in the vg1 and nodal3 clusters on the L chromosomes were also altered compared to their Xenopus tropicalis orthologs. X. laevis vg1 and nodal3 paralogs have potentially become pseudogenes or sub-functionalized genes and are expressed at different levels. As X. tropicalis has a single vg1 gene on chromosome XTR1, the ancestral vg1 gene in X. laevis appears to have been expanded on XLA1L. Of note, two reported vg1 genes, vg1(S20) and vg1(P20), reside in the cluster on XLA1L. The nodal3 gene cluster is also present on X. tropicalis chromosome XTR3, but phylogenetic analysis indicates that nodal3 genes in X. laevis and X. tropicalis were independently expanded and/or evolved in concert within each cluster by gene conversion. These findings provide insights into the function and molecular evolution of TGF-β family genes in response to allotetraploidization