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

Telomeres and sirtuins: at the end we meet again

Telomeres and sirtuins are independently implicated in causing disease and aging, but how they cooperate is not well understood. A recent study demonstrates that telomere shortening represses sirtuins and increasing sirtuin activity stabilizes telomeres and improves telomere-dependent disease, suggesting that these two pathways are tightly intertwined

Computer Use and Training of College Freshmen with Low Vision

PURPOSE: The knowledge, experiences and attitudes of computer use in college freshmen with low vision were examined by focussing on the change between two periods. Interviews were conducted first at the time of entering the college, and secondly at the 8 weeks later. METHOD: Thirty-three college freshmen with low vision were asked to reply to questionnaires regarding experience with, knowledge of, and attitudes toward computer use. The demographic and pathological characteristics of each subject were also described. RESULTS: Nearly half of the students were familiar with computers, but about twenty percent of them entered without any computer experience at all. The longer the students used computers, the more frequently they used them (r＝0.833, p＜0.01). Experiences with Word Processor, Presentation, Screen Reader, and Screen Magnifier application significantly increased after eight weeks. The relationship between the visual acuity and assistive technology use was found. The knowledge of and attitudes toward computer usage did not change during two periods