Identification and targeted disruption of the mouse gene encoding ESG1 (PH34/ECAT2/DPPA5)

BACKGROUND: Embryonic stem cell-specific gene (ESG) 1, which encodes a KH-domain containing protein, is specifically expressed in early embryos, germ cells, and embryonic stem (ES) cells. Previous studies identified genomic clones containing the mouse ESG1 gene and five pseudogenes. However, their chromosomal localizations or physiological functions have not been determined. RESULTS: A Blast search of mouse genomic databases failed to locate the ESG1 gene. We identified several bacterial artificial clones containing the mouse ESG1 gene and an additional ESG1-like sequence with a similar gene structure from chromosome 9. The ESG1-like sequence contained a multiple critical mutations, indicating that it was a duplicated pseudogene. The 5' flanking region of the ESG1 gene, but not that of the pseudogene, exhibited strong enhancer and promoter activity in undifferentiated ES cells by luciferase reporter assay. To study the physiological functions of the ESG1 gene, we replaced this sequence in ES cells with a β-geo cassette by homologous recombination. Despite specific expression in early embryos and germ cells, ESG1(-/- )mice developed normally and were fertile. We also generated ESG1(-/- )ES cells both by a second independent homologous recombination and directly from blastocysts derived from heterozygous intercrosses. Northern blot and western blot analyses confirmed the absence of ESG1 in these cells. These ES cells demonstrated normal morphology, proliferation, and differentiation. CONCLUSION: The mouse ESG1 gene, together with a duplicated pseudogene, is located on chromosome 9. Despite its specific expression in pluripotent cells and germ cells, ESG1 is dispensable for self-renewal of ES cells and establishment of germcells

Partial structure investigation of the traditional bulk metallic glass Pd40Ni40 P20

Local structures of Pd40Ni40P20 bulk metallic glass were investigated by combining anomalous x-ray scattering close to the Pd and Ni K absorption edges, x-ray diffraction, neutron diffraction, and reverse Monte Carlo modeling, from which partial structure factors Sij(Q) and partial pair distribution functions gij(r) as well as three-dimensional atomic configurations were carefully obtained around the constituent elements. A disagreement is found in the local structures with an ab initio molecular dynamics simulation by Guan et al., i.e., the existence of the P-P nearest-neighboring configurations is clarified in the present experimental result. From the Voronoi tessellation analysis, a preference of the pure icosahedral configurations is observed around the Ni atoms, whereas the local configurations around the Pd and P atoms are rather distorted icosahedra. A persistent homology analysis was carried out to identify meaningful shape characteristics of the intermediate-range atomic configuration of large rings.</p

Inventory and Evolution of Mitochondrion-localized Family A DNA Polymerases in Euglenozoa

The order Trypanosomatida has been well studied due to its pathogenicity and the unique biology of the mitochondrion. In Trypanosoma brucei, four DNA polymerases, namely PolIA, PolIB, PolIC, and PolID, related to bacterial DNA polymerase I (PolI), were shown to be localized in mitochondria experimentally. These mitochondrion-localized DNA polymerases are phylogenetically distinct from other family A DNA polymerases, such as bacterial PolI, DNA polymerase gamma (Pol&gamma;) in human and yeasts, &ldquo;plant and protist organellar DNA polymerase (POP)&rdquo; in diverse eukaryotes. However, the diversity of mitochondrion-localized DNA polymerases in Euglenozoa other than Trypanosomatida is poorly understood. In this study, we discovered putative mitochondrion-localized DNA polymerases in broad members of three major classes of Euglenozoa&mdash;Kinetoplastea, Diplonemea, and Euglenida&mdash;to explore the origin and evolution of trypanosomatid PolIA-D. We unveiled distinct inventories of mitochondrion-localized DNA polymerases in the three classes: (1) PolIA is ubiquitous across the three euglenozoan classes, (2) PolIB, C, and D are restricted in kinetoplastids, (3) new types of mitochondrion-localized DNA polymerases were identified in a prokinetoplastid and diplonemids, and (4) evolutionarily distinct types of POP were found in euglenids. We finally propose scenarios to explain the inventories of mitochondrion-localized DNA polymerases in Kinetoplastea, Diplonemea, and Euglenida