Direct targets of Klf5 transcription factor contribute to the maintenance of mouse embryonic stem cell undifferentiated state

<p>Abstract</p> <p>Background</p> <p>A growing body of evidence has shown that Krüppel-like transcription factors play a crucial role in maintaining embryonic stem cell (ESC) pluripotency and in governing ESC fate decisions. Krüppel-like factor 5 (Klf5) appears to play a critical role in these processes, but detailed knowledge of the molecular mechanisms of this function is still not completely addressed.</p> <p>Results</p> <p>By combining genome-wide chromatin immunoprecipitation and microarray analysis, we have identified 161 putative primary targets of Klf5 in ESCs. We address three main points: (1) the relevance of the pathways governed by Klf5, demonstrating that suppression or constitutive expression of single Klf5 targets robustly affect the ESC undifferentiated phenotype; (2) the specificity of Klf5 compared to factors belonging to the same family, demonstrating that many Klf5 targets are not regulated by Klf2 and Klf4; and (3) the specificity of Klf5 function in ESCs, demonstrated by the significant differences between Klf5 targets in ESCs compared to adult cells, such as keratinocytes.</p> <p>Conclusions</p> <p>Taken together, these results, through the definition of a detailed list of Klf5 transcriptional targets in mouse ESCs, support the important and specific functional role of Klf5 in the maintenance of the undifferentiated ESC phenotype.</p> <p>See: <url>http://www.biomedcental.com/1741-7007/8/125</url></p

Genome-Wide Interrogation of Mammalian Stem Cell Fate Determinants by Nested Chromosome Deletions

Understanding the function of important DNA elements in mammalian stem cell genomes would be enhanced by the availability of deletion collections in which segmental haploidies are precisely characterized. Using a modified Cre-loxP–based system, we now report the creation and characterization of a collection of ∼1,300 independent embryonic stem cell (ESC) clones enriched for nested chromosomal deletions. Mapping experiments indicate that this collection spans over 25% of the mouse genome with good representative coverage of protein-coding genes, regulatory RNAs, and other non-coding sequences. This collection of clones was screened for in vitro defects in differentiation of ESC into embryoid bodies (EB). Several putative novel haploinsufficient regions, critical for EB development, were identified. Functional characterization of one of these regions, through BAC complementation, identified the ribosomal gene Rps14 as a novel haploinsufficient determinant of embryoid body formation. This new library of chromosomal deletions in ESC (DelES: http://bioinfo.iric.ca/deles) will serve as a unique resource for elucidation of novel protein-coding and non-coding regulators of ESC activity

Three-dimensional bio-printing and bone tissue engineering: technical innovations and potential applications in maxillofacial reconstructive surgery

Background Bone grafting has been considered the gold standard for hard tissue reconstructive surgery and is widely used for large mandibular defect reconstruction. However, the midface encompasses delicate structures that are surrounded by a complex bone architecture, which makes bone grafting using traditional methods very challenging. Three-dimensional (3D) bioprinting is a developing technology that is derived from the evolution of additive manufacturing. It enables precise development of a scaffold from different available biomaterials that mimic the shape, size, and dimension of a defect without relying only on the surgeon’s skills and capabilities, and subsequently, may enhance surgical outcomes and, in turn, patient satisfaction and quality of life. Review This review summarizes different biomaterial classes that can be used in 3D bioprinters as bioinks to fabricate bone scaffolds, including polymers, bioceramics, and composites. It also describes the advantages and limitations of the three currently used 3D bioprinting technologies: inkjet bioprinting, micro-extrusion, and laser-assisted bioprinting. Conclusions Although 3D bioprinting technology is still in its infancy and requires further development and optimization both in biomaterials and techniques, it offers great promise and potential for facial reconstruction with improved outcome

Serological reports of human infections of H7 and H9 avian influenza viruses in northern China

Background: H7 and H9 subtype avian influenza viruses pose a similar threat to humans as H5 virus. Objectives: This study aims to identify the potential existence of H7 and H9 avian influenza infections in farmers and in poultry workers in northern China regions with highly pathogenic avian influenza (HPAI) H5N1 outbreaks. Study design: Sera were collected from farmers in Xinjiang Uygur autonomous region and Liaoning province and poultry workers in Shandong province. Sera from healthy residents in Shanxi province were used as the controls. H7 and H9 virus infections were examined by hemagglutination inhibition (HI) assay using horse erythrocytes. The titer equal to or greater than 1:160 was considered positive. Results: A total of 583 sera collected from farmers in Xinjiang were tested, and 10 (1.7%) were positive for H9 virus infection. Out of 200 sera collected from Liaoning, two (1.0%) were infected by H9 virus. No H7 virus infection was detected in the above serum samples. Neither H7 nor H9 virus infection was identified in 277 poultry workers of Shandong and in 407 residents of Shanxi. Conclusions: Although H9 virus infection was limited in farmers from Xinjiang and Liaoning, a public health alert is needed as novel pandemic influenza strains may develop unnoticed given the presence of subclinical infections, and the possibility of re-assortment with prevailing H5N1 virus in these regions. Published by Elsevier B.V

Monitoring of atmospheric radionuclides from the Fukushima nuclear accident and assessing their impact on Xi'an, China

Aerosol radionuclides (I-131, Cs-134, Cs-137) and gaseous radioactive xenon (Xe-133) were monitored at Xi&#39;an, China following the accident at the Fukushima nuclear power plant in March 2011. The additional annual effective dose attributable to the Fukushima emissions was much lower than the public annual effective dose from natural radiation, according to Chinese national standards. The monitoring results were compared with data from other countries as well as with the radionuclide concentrations observed in Xi&#39;an after the Chernobyl nuclear accident in 1986. Possible transport pathways of the released radionuclides from Fukushima to Xi&#39;an were investigated. The occurrence of an anticyclone in the Pacific Ocean region and the extended period over which the radionuclides were released made the determination transport pathways complex, but divergence in the plume and easterly flow evidently brought the initial suite of radionuclides to Xi&#39;an.</p