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51.
52.
To examine whether trajectories of participation in organized activities during the high school years and beyond (from ages 14 to 20) predicted outcomes at age 21 (externalizing problems, internalizing problems, civic engagement, number of years of education, and perception of physical health), 354 youths (60% girls) were surveyed annually over nine years. Four trajectories were found: (a) “Low and decreasing” (71%), (b) “Moderate and stable” (12%), (c) “High and decreasing after high school” (12%), and (d) “High and increasing after high school” (5%). Results revealed that the predicted outcomes varied according to the different trajectories. Pursuing high levels of activity participation beyond high school was especially beneficial with respect to externalizing problems and educational attainment. 相似文献
53.
Sequence, organization, and evolution of the A+T region of Drosophila melanogaster mitochondrial DNA 总被引:2,自引:0,他引:2
The long (4.6-kb) A+T region of Drosophila melanogaster mitochondrial DNA
has been cloned and sequenced. The A+T region is organized in two large
arrays of tandemly repeated DNA sequence elements, with nonrepetitive
intervening and flanking sequences comprising only 22% of its length. The
first repeat array consists of five repeats of 338-373 bp. The second
consists of four intact 464-bp repeats and a fifth partial repeat of 137
bp. Three DNA sequence elements are found to be highly conserved in D.
melanogaster and in several Drosophila species with short A+T regions.
These include a 300-bp DNA sequence element that overlaps the DNA
replication origin and two thymidylate stretches identified on opposite DNA
strands. We conclude that the length heterogeneity observed in the A+T
regulatory region in mitochondrial DNAs from the genus Drosophila results
from the expansion (and contraction) of the number of repeated DNA sequence
elements. We also propose that the 300-bp conserved DNA sequence element,
in conjunction with another primary sequence determinant, perhaps the
adjacent thymidylate stretch, functions in the regulation of mitochondrial
DNA replication.
相似文献
54.
The objective of this study was to compare the sensitivity of a new test method with the smear method for detection of neoplasia of the uterine cervix. The new procedure, the ThinPrep process, is an automated, fluid-based technique for the collection and preparation of exfoliated and aspirated cytologic specimens. A single sample from each patient was split and prepared both with the smear and test methods. The diagnostic results from the two slides were compared in this blind study. Among a total of 2,655 patients, diagnoses concurred in 92% of cases and were within one diagnostic level of each other 98% of the time. The ThinPrep method facilitated the detection of more low-grade lesions (P less than .001, McNemar's test). In addition, the test method decreased the number of ambiguous interpretations. The ThinPrep method appears to improve the cervical cytologic smear quality by the harvest of a random and reproducible sample, with a reduction in artifacts. The new method improves the sensitivity of the cervical cytologic screening test. 相似文献
55.
Clifford DL Folmes D Kent Arrell Jelena Zlatkovic-Lindor Almudena Martinez-Fernandez Carmen Perez-Terzic Timothy J Nelson Andre Terzic 《Cell cycle (Georgetown, Tex.)》2013,12(15):2355-2365
Nuclear reprogramming resets differentiated tissue to generate induced pluripotent stem (iPS) cells. While genomic attributes underlying reacquisition of the embryonic-like state have been delineated, less is known regarding the metabolic dynamics underscoring induction of pluripotency. Metabolomic profiling of fibroblasts vs. iPS cells demonstrated nuclear reprogramming-associated induction of glycolysis, realized through augmented utilization of glucose and accumulation of lactate. Real-time assessment unmasked downregulated mitochondrial reserve capacity and ATP turnover correlating with pluripotent induction. Reduction in oxygen consumption and acceleration of extracellular acidification rates represent high-throughput markers of the transition from oxidative to glycolytic metabolism, characterizing stemness acquisition. The bioenergetic transition was supported by proteome remodeling, whereby 441 proteins were altered between fibroblasts and derived iPS cells. Systems analysis revealed overrepresented canonical pathways and interactome-associated biological processes predicting differential metabolic behavior in response to reprogramming stimuli, including upregulation of glycolysis, purine, arginine, proline, ribonucleoside and ribonucleotide metabolism, and biopolymer and macromolecular catabolism, with concomitant downregulation of oxidative phosphorylation, phosphate metabolism regulation, and precursor biosynthesis processes, prioritizing the impact of energy metabolism within the hierarchy of nuclear reprogramming. Thus, metabolome and metaboproteome remodeling is integral for induction of pluripotency, expanding on the genetic and epigenetic requirements for cell fate manipulation. 相似文献
56.
EDC3 phosphorylation regulates growth and invasion through controlling P‐body formation and dynamics
Jeremiah J Bearss Sathish KR Padi Neha Singh Marina CardoVila Jin H Song Ghassan Mouneimne Nikita Fernandes Yang Li Matthew R Harter Jaime MC Gard Anne E Cress Wolfgang Peti Andrew DL Nelson J Ross Buchan Andrew S Kraft Koichi Okumura 《EMBO reports》2021,22(4)
Regulation of mRNA stability and translation plays a critical role in determining protein abundance within cells. Processing bodies (P‐bodies) are critical regulators of these processes. Here, we report that the Pim1 and 3 protein kinases bind to the P‐body protein enhancer of mRNA decapping 3 (EDC3) and phosphorylate EDC3 on serine (S)161, thereby modifying P‐body assembly. EDC3 phosphorylation is highly elevated in many tumor types, is reduced upon treatment of cells with kinase inhibitors, and blocks the localization of EDC3 to P‐bodies. Prostate cancer cells harboring an EDC3 S161A mutation show markedly decreased growth, migration, and invasion in tissue culture and in xenograft models. Consistent with these phenotypic changes, the expression of integrin β1 and α6 mRNA and protein is reduced in these mutated cells. These results demonstrate that EDC3 phosphorylation regulates multiple cancer‐relevant functions and suggest that modulation of P‐body activity may represent a new paradigm for cancer treatment. 相似文献
57.
TL Kieft EM Murphy DL Haldeman PS Amy BN Bjornstad EV McDonald DB Ringelberg DC White J Stair RP Griffiths TC Gsell WE Holben DR Boone 《Microbial ecology》1998,36(3):336-348
Abstract Two chronosequences of unsaturated, buried loess sediments, ranging in age from <10,000 years to >1 million years, were investigated to reconstruct patterns of microbial ecological succession that have occurred since sediment burial. The relative importance of microbial transport and survival to succession was inferred from sediment ages, porewater ages, patterns of abundance (measured by direct counts, counts of culturable cells, and total phospholipid fatty acids), activities (measured by radiotracer and enzyme assays), and community composition (measured by phospholipid fatty acid patterns and Biolog substrate usage). Core samples were collected at two sites 40 km apart in the Palouse region of eastern Washington State, near the towns of Washtucna and Winona. The Washtucna site was flooded multiple times during the Pleistocene by glacial outburst floods; the Winona site elevation is above flood stage. Sediments at the Washtucna site were collected from near surface to 14.9 m depth, where the sediment age was approximately 250 ka and the porewater age was 3700 years; sample intervals at the Winona site ranged from near surface to 38 m (sediment age: approximately 1 Ma; porewater age: 1200 years). Microbial abundance and activities declined with depth at both sites; however, even the deepest, oldest sediments showed evidence of viable microorganisms. Same-age sediments had equal quantities of microorganisms, but different community types. Differences in community makeup between the two sites can be attributed to differences in groundwater recharge and paleoflooding. Estimates of the microbial community age can be constrained by porewater and sediment ages. In the shallower sediments (<9 m at Washtucna, <12 m at Winona), the microbial communities are likely similar in age to the groundwater; thus, microbial succession has been influenced by recent transport of microorganisms from the surface. In the deeper sediments, the populations may be considerably older than the porewater ages, since microbial transport is severely restricted in unsaturated sediments. This is particularly true at the Winona site, which was never flooded. 相似文献
58.
This paper reports on specific open and interconnected CO(2) foams of poly(L-lactic acid). The effect of varying gas concentration and hence physical changes induced by CO(2) has been investigated and thus used to generate specific structures. The developed morphologies have a skin core structure with larger pores in the core and open and interconnected smaller pores in the skin. 相似文献
59.
60.
Selective neutrality of glucose-6-phosphate dehydrogenase allozymes in Escherichia coli 总被引:2,自引:0,他引:2
Six naturally occurring alleles representing four electromorphs of the
enzyme glucose-6-phosphate dehydrogenase were transferred by P1- mediated
transduction from natural isolates of Escherichia coli into the genetic
background of E. coli K12 and were studied in pairwise competition in
chemostats limited for glucose in order to estimate differences in growth
rate associated with the alleles. Although the level of resolution of such
experiments is a growth rate differential of approximately 0.002 h-1, no
significant differences among the strains were found. Studies of apparent
Km and Vmax in crude enzyme extracts of the strains also failed to reveal
any significant differences among the electromorphs. These results support
the view that the alleles are selectively neutral or nearly neutral under
these conditions.
相似文献