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171.
Background
In vertebrates, the myelin sheath is essential for efficient propagation of action potentials along the axon shaft. Oligodendrocytes are the cells of the central nervous system that create myelin sheaths. During embryogenesis, ventral neural tube precursors give rise to oligodendrocyte progenitor cells, which divide and migrate throughout the central nervous system. This study aimed to investigate mechanisms that regulate oligodendrocyte progenitor cell formation.Methodology/Principal Findings
By conducting a mutagenesis screen in transgenic zebrafish, we identified a mutation, designated vu166, by an apparent reduction in the number of oligodendrocyte progenitor cells in the dorsal spinal cord. We subsequently determined that vu166 is an allele of pescadillo, a gene known to play a role in ribosome biogenesis and cell proliferation. We found that pescadillo function is required for both the proper number of oligodendrocyte progenitors to form, by regulating cell cycle progression, and for normal levels of myelin gene expression.Conclusions/Significance
Our data provide evidence that neural precursors require pes function to progress through the cell cycle and produce oligodendrocyte progenitor cells and for oligodendrocyte differentiation. 相似文献172.
Søren Bastholm Lasse Wahlstrøm Louise Appel Bjergbæk Peter Roslev 《World journal of microbiology & biotechnology》2008,24(10):2323-2330
Traditional cultivation-dependent tests for coliform bacteria in food and drinking water take 18–24 h to complete. Bioluminescence-based
enzyme assays can potentially reduce analysis time for indicator bacteria such as coliforms. In the present study, we developed
a simple presence/absence (P/A) bioluminescence procedure for rapid detection of coliform bacteria in groundwater-based drinking
water. The bioluminescence procedure targeting β-d-galactosidase activity in coliform bacteria was based on hydrolysis of 6-O-β-galactopyranosyl-luciferin. Bacteria immobilized on membrane filters were enriched for 6–8 h in selective media containing
isopropyl-β-d-thiogalactopyranoside (IPTG) to induce β-d-galactosidase activity in coliform bacteria. The equivalent of approximately 300 E. coli cells was required for bioluminescence detection of β-d-galactosidase activity. In comparison, PCR based detection of E. coli in drinking water required approximately 30 target cells. Analysis of contaminated drinking water samples showed comparable
results for coliform bacteria using traditional multiple-tube fermentation, Colilert-18, and the bioluminescence procedure.
Aeromonas hydrophila or indigenous groundwater bacteria did not interfere with the procedure. The bioluminescence procedure can be combined with
commercial substrates such as Fluorocult or Colilert-18, and will allow the detection of one coliform in 100 ml drinking water
within one working day. The results suggest the bioluminescence assays targeting β-d-galactosidase activity may be used for or for early warning screening of drinking water and/or rapid identification of contaminated
drinking water wells. 相似文献
173.
Background
The goal of DNA barcoding is to develop a species-specific sequence library for all eukaryotes. A 650 bp fragment of the cytochrome c oxidase 1 (CO1) gene has been used successfully for species-level identification in several animal groups. It may be difficult in practice, however, to retrieve a 650 bp fragment from archival specimens, (because of DNA degradation) or from environmental samples (where universal primers are needed).Results
We used a bioinformatics analysis using all CO1 barcode sequences from GenBank and calculated the probability of having species-specific barcodes for varied size fragments. This analysis established the potential of much smaller fragments, mini-barcodes, for identifying unknown specimens. We then developed a universal primer set for the amplification of mini-barcodes. We further successfully tested the utility of this primer set on a comprehensive set of taxa from all major eukaryotic groups as well as archival specimens.Conclusion
In this study we address the important issue of minimum amount of sequence information required for identifying species in DNA barcoding. We establish a novel approach based on a much shorter barcode sequence and demonstrate its effectiveness in archival specimens. This approach will significantly broaden the application of DNA barcoding in biodiversity studies. 相似文献174.
Krelin Y Zhang L Kang TB Appel E Kovalenko A Wallach D 《Cell death and differentiation》2008,15(9):1350-1355
Caspase-8 is frequently deficient in several kinds of human tumors, suggesting that certain effects of this enzyme restrict tumor development. To examine the nature of the cellular function whose regulation by caspase-8 contributes to its antitumor effect, we assessed the impact of caspase-8 deficiency on cell transformation in vitro. Caspase-8-deficient mouse embryonic fibroblasts immortalized with the SV40 T antigen did not survive when cultured in soft agar, and were nontumorogenic in nude mice. However, the rate of transformation of these cells during their continuous growth in culture, as reflected in the observed emergence of cells that do grow in soft agar and are able to form tumors in nude mice, was far higher than that of cells expressing caspase-8. These findings indicate that caspase-8 deficiency can contribute to cancer development in a way that does not depend on the enzyme's participation in killing of the tumor cells by host immune cytotoxic mechanisms, or on its involvement in the cell-death process triggered upon detachment of the cells from their substrate, but rather concerns cell-autonomous mechanisms that affect the rate of cell transformation. 相似文献
175.
Ard JD Kumanyika S Stevens VJ Vollmer WM Samuel-Hodge C Kennedy B Gayles D Appel LJ Brantley PJ Champagne C Charleston J Svetkey LP 《Obesity (Silver Spring, Md.)》2008,16(2):306-310
Objective: We do not know how racial composition of a group influences behavior change for African Americans (AAs) in group‐based weight loss programs. We tested the hypothesis that AA who participate in all AA weight loss intervention groups will lose more weight than AA who participate in mixed race groups. Methods and Procedures: This observational study was ancillary to Phase 1 of the Weight Loss Maintenance Study, a multi‐center trial of strategies to maintain weight loss after a 20‐week behavior modification program. Three of four centers recruited several all‐AA intervention groups. Remaining groups were combinations of AA and non‐AA participants. All participants received the same weight loss intervention. Change in weight was the primary outcome, comparing participants of all‐AA groups with AA participants of mixed race groups conducted by the same AA interventionists. Secondary outcomes included measures of intervention adherence and behavior change. Results: Participants of all‐AA groups (n = 271) were comparable to other AA participants (n = 106). The mean proportion of AA in mixed race groups was 56%. All‐AA group participants had similar weight loss as those in mixed groups (?4.2 vs. ?4.2 kg, P = 0.97). There were no differences between the groups in mean number of sessions attended or changes in dietary intake. Discussion: Significant weight loss was observed in both groups, with no effect of group composition on adherence or weight loss outcomes. Special logistics to accommodate all‐AA groups may not be necessary. Despite varying instructional environments, AA appeared to respond positively to intervention messages with significant changes in dietary intake, physical activity (PA), and weight. 相似文献
176.
O. Appel 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1938,10(1):21-24
Ohne Zusammenfassung 相似文献
177.
John D. Peterson John E. Steffen Laura K. Reinert Paul A. Cobine Arthur Appel Louise Rollins-Smith Mary T. Mendon?a 《PloS one》2013,8(4)
Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis, has contributed to worldwide amphibian population declines; however, the pathogenesis of this disease is still somewhat unclear. Previous studies suggest that infection disrupts cutaneous sodium transport, which leads to hyponatremia and cardiac failure. However, infection is also correlated with unexplained effects on appetite, skin shedding, and white blood cell profiles. Glucocorticoid hormones may be the biochemical connection between these disparate effects, because they regulate ion homeostasis and can also influence appetite, skin shedding, and white blood cells. During a laboratory outbreak of B. dendrobatidis in Australian Green Tree Frogs, Litoria caerulea, we compared frogs showing clinical signs of chytridiomycosis to infected frogs showing no signs of disease and determined that diseased frogs had elevated baseline corticosterone, decreased plasma sodium and potassium, and altered WBC profiles. Diseased frogs also showed evidence of poorer body condition and elevated metabolic rates compared with frogs showing no signs of disease. Prior to displaying signs of disease, we also observed changes in appetite, body mass, and the presence of shed skin associated with infected but not yet diseased frogs. Collectively, these results suggest that elevated baseline corticosterone is associated with chytridiomycosis and correlates with some of the deleterious effects observed during disease development. 相似文献
178.
The perturbed angular correlation (PAC) technique has been applied to study the electric quadrupole interaction of 181Hf nuclei at the binding sites of ovotransferrin (OTF) molecules. Two specific electric field gradients were observed. Their relative intensities depend on the pH value and the temperature of the samples, whereas the electric quadrupole interaction parameters themselves remain unaffected. In order to compare the binding sites in OTF, experiments with N- and C-terminal half-molecules were performed. Both specific configurations are observed at the N-terminal and at the C-terminal binding site with similar quadrupole parameters as for the intact protein. Remarkably, the stability of the hafnium binding to the C-terminal fragment appears to be reduced as compared with the N-terminal half and the intact protein. 相似文献
179.
Peter Wagner Michael Hoever Katrin Appel Walter Knöchel Mathias Montenarh 《Development genes and evolution》1995,204(3):198-202
Recently we cloned tms1 (a putative dehydrogenase) by complementation of a human tumour-derived mutant p53 induced growth arrest in fission yeast. Microinjection of purified tmsl protein into Xenopus laevis embryos abrogated normal embryo development by causing cleavage retardation or cleavage arrest of injected blastomeres in a concentration dependant manner, whereas injection of specific affinity purified tms1 antiserum showed no significant morphological defects. Microinjection of tms1 protein together with affinity purified tms1 antibody resulted in a significantly reduced number of cleavage arrested embryos. 相似文献
180.
The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana 总被引:1,自引:1,他引:0
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The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation. 相似文献