Chic chicks: the evolution of chick ornamentation in rails

Competition over access to food has led to the evolution ofa variety of exaggerated visual and vocal displays in altricialnestling birds. Precocial chicks that are fed by their parentsalso vary widely in appearance ranging from those with inconspicuouscoloration to those with brightly colored bills, fleshy parts,and plumes. These ornaments are lost by the end of the periodof parental dependence, suggesting they function in competitionover parental care. We use a comparative approach to evaluatewhich ecological or life-history variables may have favoredthe evolution of conspicuous ornamentation in precocial chicks.We compiled data on chick morphology, ecology, and social organizationof species in the Family Rallidae, a group with highly variabledowny chicks. Chick ornamentation in the form of brightly coloredbills, fleshy patches, or plumes is observed in 36 of 97 speciesfor which downy chicks are described. Phylogenetic reconstructionssuggest that nonornamentation is the ancestral state. Chickornamentation has evolved multiple times within the Rallidaeand is significantly associated with large clutch sizes andpolygamous mating systems. Chick ornamentation was also weaklyassociated with adult ornamentation and adult dimorphism. Weargue that these results support the hypothesis that lineageswith higher levels of sibling competition are more likely toevolve ornamented chicks.     

Vasculogeneic maturation of E14 embryonic stem cells with evidence of early vascular endothelial growth factor independency

Murine embryonic stem cells (ESC) provide a unique homogeneous cell system for studying early vasculogenic cell differentiation in vitro. In this report, we characterized endothelial development of cultured E14 ESCs and mapped the effects of vascular endothelial growth factor (VEGF) on these cells. After removal of leukemia inhibitory factor undifferentiated state ESCs were precultured for 6 days and then cultured for up to 30 days in differentiation culture medium, with or without supplemental VEGF. ELISA analysis was used to detect endogenous VEGF levels. Early vasculogenic development and expression of selected genes were characterized using flow cytometry for specific antigens and quantitative RT-PCR. ELISA analysis showed no endogenous VEGF after preculture and at day 2 in unsupplemented culture, therafter VEGF levels rise. Directly after preculture a high proportion (36%) of the ESCs showed positivity for endothelial CD31. We describe characteristic endothelial differentiation patterns in embryoid bodies (EB) kept in culture for up to 30 days. VEGF supplementation lead to qualitative changes in the EB vessels, specific activation of vasculogenesis-related genes (CD31, CD144, and ERG) and temporary down-regulation of the VEGF receptor gene flk-1. VEGF supplementation did not produce measurable changes in the endothelial cell fractions as judged by surface antigen presence. We conclude that early ESCs may undergo endothelial differentiation through VEGF-independent pathways, whereas endothelial cell patterns in EBs are cytokine dependent and fully stimulated by endogenous cytokine levels.     

Macrophages in the embryo and beyond: much more than just giant phagocytes

Originally recognized as an essential part of the innate and acquired immune systems, macrophages emerged as omnipresent and influential regulators of embryo- and organo-genesis, as well as of tissue and tumor growth. Macrophages are present essentially in all tissues, beginning with embryonic development and, in addition to their role in host defense and in the clearance of apoptotic cells, are being increasingly recognized for their trophic function and role in regeneration. Some tissue macrophages are also found to possess a substantial potential for autonomous self-renewal. Macrophages are associated with a significant proportion of malignant tumors and are widely recognized for their angiogenesis-promoting and trophic roles, making them one of the new promising targets for cancer therapies. Recent expression profiling of embryonic macrophages from different tissues revealed remarkable consistency of their gene expression profiles, independent of their tissue of origin, as well as their similarities with tumor-associated macrophages. Macrophages are also capable of fusion with other cells in tissue repair and metastasizing tumors, as well as with each other in the immune response and osteoclastogenesis.     

寒冷刺激支气管上皮细胞产生外泌体促肺成纤维细胞表达气道重塑相关因子

外泌体可由多种细胞分泌,是具有多种生物学功能的细胞外囊泡,但其在气道重塑中的作用尚不明确。为探讨经寒冷刺激的人支气管上皮细胞（BEAS-2B）分泌的外泌体对人胚肺成纤维细胞(HLF1)气道重塑相关因子表达的影响,收集BEAS-2B细胞株培养液提取外泌体,利用透射电镜及Western印迹对外泌体进行其大小、形态及标志性蛋白的检测;提取的外泌体与HLF1共同培育,分别设置空白对照组、正常对照组（加入未作干预的BEAS 2B细胞所产的外泌体）及寒冷刺激组（加入经寒冷刺激后的BEAS-2B细胞所产的外泌体）。运用Real-time-PCR及Western印迹技术,分别检测各组HLF1表达FGF-2、TNF-α、MMP-9的mRNA及蛋白情况。结果显示,提取BEAS-2B细胞分泌的外泌体为直径小于100 nm的圆形或椭圆形结构,并表达外泌体标志性蛋白CD9、TSG101、ALIX;寒冷刺激组24 h后,其FGF-2、TNF-α、MMP-9的mRNA及蛋白表达均显著高于空白对照组及正常对照组（均P<0.05）。本研究结果表明,BEAS-2B细胞能够释放外泌体;经寒冷刺激后的BEAS 2B细胞所释放的外泌体可以携带并传递生物信号,诱导HLF1表达气道重塑相关因子。     

胚胎干细胞移植治疗糖尿病的研究进展

糖尿病是一种严重的免疫缺陷性疾病,目前的治疗方法很难从根本上治愈。近年来的研究表明,通过诱导胚胎干细胞定向分化为胰岛β细胞,并进行移植治疗糖尿病,是一种有希望的根治方案。本文就利用胚胎干细胞移植治疗糖尿病的最新进展作一综述。     

Spatial distribution and initial changes of SSEA-1 and other cell adhesion-related molecules on mouse embryonic stem cells before and during differentiation.

We examined the distribution of cell adhesion-related molecules (CAMs) among mouse embryonic stem (ES) cells and the spatial distribution on cell surfaces before and during differentiation. The cell-cell heterogeneity of SSEA-1, PECAM-1, and ICAM-1 among the undifferentiated cells in the ES cell colonies was evident by immunohistochemistry and immuno-SEM, supporting the flow cytometry findings. In contrast, most undifferentiated ES cells strongly expressed CD9. SSEA-1 was located preferentially on the edge of low protuberances and microvilli and formed clusters or linear arrays of 3-20 particles. PECAM-1 and ICAM-1 were randomly localized on the free cell surfaces, whereas CD9 was preferentially localized on the microvilli or protuberances, especially in the cell periphery. Both the SSEA-1(+) fraction and the SSEA-1(-) fraction of magnetic cell sorting (MACS) formed undifferentiated colonies after plating. Flow cytometry showed that these populations reverted separately again to a culture with a mixed phenotype. Differentiation induced by retinoic acid downregulated the expression of all CAMs. Immuno-SEM showed decreases of SSEA-1 in the differentiated ES cells, although some clustering still remained. Our findings help to elucidate the significance of these molecules in ES cell maintenance and differentiation and suggest that cell surface antigens may be useful for defining the phenotype of undifferentiated and differentiated ES cells.     

Paracrine promotion of cardiomyogenesis in embryoid bodies by LIF modulated endoderm

In the vertebrate embryo the heart is the first organ to form. Embryonic and extra-embryonic tissues are supposed to contribute to cardiac lineage commitment before and during gastrulation in a paracrine fashion. Evidence has accumulated that factors secreted by the anterior lateral endoderm and extra-embryonic endoderm contribute to cardiomyogenesis. Here we exploit in vitro differentiation of embryonic stem cells in embryoid bodies to study differentiation of the extraembryonic endodermal lineage, gastrulation-like processes, and the influence of endoderm on cardiomyogenesis. We demonstrate that in embryoid bodies primitive endoderm differentiates to visceral and parietal endoderm and that parietal endoderm influences onset of cardiomyogenesis in a concentration-dependent manner. Both increased concentrations of leukemia inhibitory factor and its absence in lif-/- embryoid bodies hampered parietal endoderm formation. Reduced differentiation of parietal endoderm correlated with an attenuation of cardiomyogenesis even in the presence of LIE These and previous results suggest that leukemia inhibitory factor is directly and indirectly, via endoderm formation, involved in the regulation of cardiomyogenesis. Increased proliferation of parietal endoderm in lifr -/- embryoid bodies and addition of conditioned lif -/- cell culture supernatant promoted cardiomyogenesis, demonstrating for the first time that parietal endoderm also contributes to cardiomyogenesis in embryoid bodies in a paracrine and leukemia inhibitory factor and its receptor independent pathway. New factors signaling independently of the leukemia inhibitory-factor receptor pathway may sustain cardiomyocyte cell proliferation and thus be a future target for gene therapy of cardiomyopathies and cell therapy of the myocardium.     

Activity of Embryonic Mink Genome during Diapause (Cytogenetic Analysis): Nucleolar and Extranucleolar RNA Synthesis

The nucleolar and extranucleolar RNA synthesis was studied in the mink blastocysts at different stages of embryonic diapause and during the periimplantation period using cytoradioautography. The data obtained suggest a differential and stage specific activity of the embryonic mRNA and rRNA synthesis during the period of delayed implantation.