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The egg yolk of immunized chicken is a rich and inexpensive source of specific polyclonal antibodies. In this paper we show that 20-30 micrograms of a highly conserved mammalian protein, as exemplified by proliferating cell nuclear antigen, are sufficient to induce an immune response. Immunoblot analysis revealed that specific antibodies appeared 20 days after immunization, reached a plateau after 30 days, and remained high until at least day 81. A total amount of 4 g immunoglobulin was extracted from 62 eggs of one immunized hen, yielding approximately 130 mg of specific antibodies.

This mouse model is able to recognize immunogenic modifications of human IgG1. While the degree of stress-induced aggregation varies for different mAbs, our findings using a particular mAb (mAb1) demonstrate that non-covalently modified aggregates do not break tolerance, contrary to widely held opinion. The immunogenic potential of soluble aggregates of human IgG strongly depends on the presence of neo-epitopes resulting from harsh stress conditions, i.e. extensive exposure to artificial light.

To gain insight into the molecular regulation of human heart development, a detailed comparison of the mRNA and miRNA transcriptomes across differentiating human-induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and biopsies from fetal, adult, and hypertensive human hearts was performed. Gene ontology analysis of the mRNA expression levels of the hiPSCs differentiating into cardiomyocytes revealed 3 distinct groups of genes: pluripotent specific, transitional cardiac specification, and mature cardiomyocyte specific. Hierarchical clustering of the mRNA data revealed that the transcriptome of hiPSC cardiomyocytes largely stabilizes 20 days after initiation of differentiation. Nevertheless, analysis of cells continuously cultured for 120 days indicated that the cardiomyocytes continued to mature toward a more adult-like gene expression pattern. Analysis of cardiomyocyte-specific miRNAs (miR-1, miR-133a/b, and miR-208a/b) revealed an miRNA pattern indicative of stem cell to cardiomyocyte specification. A biostatistitical approach integrated the miRNA and mRNA expression profiles revealing a cardiomyocyte differentiation miRNA network and identified putative mRNAs targeted by multiple miRNAs. Together, these data reveal the miRNA network in human heart development and support the notion that overlapping miRNA networks re-enforce transcriptional control during developmental specification.

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