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451.
Oxidative epithelial host defense is regulated by infectious and inflammatory stimuli 总被引:1,自引:0,他引:1
Monica Valencia Gattas Radia Forteza Miryam A. Fragoso Nevis Fregien Pedro Salas Matthias Salathe Gregory E. Conner 《Free radical biology & medicine》2009,47(10):1450-1458
Epithelia express oxidative antimicrobial protection that uses lactoperoxidase (LPO), hydrogen peroxide (H2O2), and thiocyanate to generate the reactive hypothiocyanite. Duox1 and Duox2, found in epithelia, are hypothesized to provide H2O2 for use by LPO. To investigate the regulation of oxidative LPO-mediated host defense by bacterial and inflammatory stimuli, LPO and Duox mRNA were followed in differentiated primary human airway epithelial cells challenged with Pseudomonas aeruginosa flagellin or IFN-γ. Flagellin upregulated Duox2 mRNA 20-fold, but upregulated LPO mRNA only 2.5-fold. IFN-γ increased Duox2 mRNA 127-fold and upregulated LPO mRNA 10-fold. DuoxA2, needed for Duox2 activity, was also upregulated by flagellin and IFN-γ. Both stimuli increased H2O2 synthesis and LPO-dependent killing of P. aeruginosa. Reduction of Duox1 by siRNA showed little effect on basal H2O2 production, whereas Duox2 siRNA markedly reduced basal H2O2 production and resulted in an 8-fold increase in Nox4 mRNA. In conclusion, large increases in Duox2-mediated H2O2 production seem to be coordinated with increases in LPO mRNA and, without increased LPO, H2O2 levels in airway secretion are expected to increase substantially. The data suggest that Duox2 is the major contributor to basal H2O2 synthesis despite the presence of greater amounts of Duox1. 相似文献
452.
Small nuclear ribonucleoprotein particle assembly in vivo: demonstration of a 6S RNA-free core precursor and posttranslational modification 总被引:38,自引:0,他引:38
The in vivo synthesis and assembly of human small nuclear ribonucleoproteins (snRNPs) have been studied using pulse/chase analysis. Antibodies derived from patients with systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD) recognize distinguishable subsets of pulse-labeled snRNP peptides. These antibodies were used to immunoprecipitate sucrose gradient fractionated pulse-labeled and pulse/chased snRNP proteins. The results indicate that assembly of the U RNA-containing snRNPs is a multistep process involving prior assembly of an RNA-free 6S core particle. This precursor contains snRNP peptides D, E, F, and G, which are common to all the different U RNA-containing particles. Furthermore, a posttranslational modification of one of the U1 snRNP-specific peptides has been observed, and the kinetics of this process indicates that the modification occurs after particle assembly. Functional and structural implications of a protein core for snRNP particles are discussed. 相似文献
453.
A symbiotic relationship of energy metabolism between a ‘non-glycolytic’ mammalian red cell and the liver 总被引:1,自引:0,他引:1
The red cell of newborn pig loses the ability to carry out glycolysis within a month after birth. The metabolic energy source for this ‘non-glycolytic’ mammalian red cell is unknown. Hepatectomy of an adult pig results in the loss of red cell ATP with a characteristic half-time of 7–8 h which is identical to the rate with which ATP disappears in the pig cells under in vitro substrate-free incubation. Exposure of pig red cells with either normal or depleted levels of ATP to isolated hepatocytes causes a net synthesis of red cell ATP during a 12 h incubation. These findings suggest that a symbiotic relationship of energy metabolism may exist between the red cell and the liver of the pig. 相似文献
454.
Arthur J Zaug Ci Ji Lim Conner L Olson Maria T Carilli Karen
J Goodrich Deborah
S Wuttke Thomas
R Cech 《Nucleic acids research》2021,49(20):11653
The CST complex (CTC1-STN1-TEN1) has been shown to inhibit telomerase extension of the G-strand of telomeres and facilitate the switch to C-strand synthesis by DNA polymerase alpha-primase (pol α-primase). Recently the structure of human CST was solved by cryo-EM, allowing the design of mutant proteins defective in telomeric ssDNA binding and prompting the reexamination of CST inhibition of telomerase. The previous proposal that human CST inhibits telomerase by sequestration of the DNA primer was tested with a series of DNA-binding mutants of CST and modeled by a competitive binding simulation. The DNA-binding mutants had substantially reduced ability to inhibit telomerase, as predicted from their reduced affinity for telomeric DNA. These results provide strong support for the previous primer sequestration model. We then tested whether addition of CST to an ongoing processive telomerase reaction would terminate DNA extension. Pulse-chase telomerase reactions with addition of either wild-type CST or DNA-binding mutants showed that CST has no detectable ability to terminate ongoing telomerase extension in vitro. The same lack of inhibition was observed with or without pol α-primase bound to CST. These results suggest how the switch from telomerase extension to C-strand synthesis may occur. 相似文献
455.
456.
Amy M. Iler Paul J. CaraDonna Lea K. Richardson Elizabeth T. Wu Jeremie B. Fant Kelly C. Pfeiler Grace A. Freymiller Kimber N. Godfrey Alexander J. Gorman Nicholas Wilson Malachi D. Whitford Grant A. Edmonds Conner Stratton Erik S. Jules 《American journal of botany》2023,110(2):e16112
Premise
Phenological variation among individuals within populations is common and has a variety of ecological and evolutionary consequences, including forming the basis for population-level responses to environmental change. Although the timing of life-cycle events has genetic underpinnings, whether intraspecific variation in the duration of life-cycle events reflects genetic differences among individuals is poorly understood.Methods
We used a common garden experiment with 10 genotypes of Salix hookeriana (coastal willow) from northern California, United States to investigate the extent to which genetic variation explains intraspecific variation in the timing and duration of multiple, sequential life-cycle events: flowering, leaf budbreak, leaf expansion, fruiting, and fall leaf coloration. We used seven clones of each genotype, for a total of 70 individual trees.Results
Genotype affected each sequential life-cycle event independently and explained on average 62% of the variation in the timing and duration of vegetative and reproductive life-cycle events. All events were significantly heritable. A single genotype tended to be “early” or “late” across life-cycle events, but for event durations, there was no consistent response within genotypes.Conclusions
This research demonstrates that genetic variation can be a major component underlying intraspecific variation in the timing and duration of life-cycle events. It is often assumed that the environment affects durations, but we show that genetic factors also play a role. Because the timing and duration of events are independent of one another, our results suggest that the effects of environmental change on one event will not necessarily cascade to subsequent events. 相似文献457.
The relationship of the hemipenis to the cloaca in copula and sperm storage and transport in the female oviduct were studied in Anolis carolinensis using light and scanning electron microscopy. During copulation, the hemipenis does not penetrate beyond the cloaca, but the two apical openings of the bifurcate sulcus spermaticus appose the openings of the oviducts from the cloaca. Sperm enter the sperm storage tubules between 2 and 6 hr after insemination and small amounts of sperm reach the infundibulum 6 to 24 hr following mating. Sperm storage tubules are embedded in the wall of the utero-vaginal transition, and are formed by the folding and fusion of the oviducal epithelium. The importance of the hemipenile-cloacal relationship and the role of sperm storage in the life history of A. carolinensis are discussed. 相似文献
458.
Separation of factors containing R-locus genes in Mormoniella stocks derived from aberrant segregation following incompatible crosses 总被引:1,自引:0,他引:1
Four stocks derived from aberrant segregation of R-locus genes in male progeny following incompatible crosses in Mormoniella have shown characteristics suggesting that genes found on added chromosomal fragments in these stocks have separated from each other. In most cases, this separation was associated with elevated temperatures at the time of and subsequent to fertilization. Data also suggest that the R-locus genes involved are adjacent to a centromere, with the O factor being proximal thereto. 相似文献
459.
460.
S. V. Raikar C. Bryant R. Braun A. J. Conner M. C. Christey 《Plant biotechnology reports》2007,1(3):175-177
The application of strand displacement amplification (SDA) is demonstrated for whole genome amplification from nanograms to
micrograms for DNA isolated from small plant cell colonies. Secondary digest amplified fragment length polymorphism (SD-AFLP)
analysis confirmed that the amplified genome is a representative of the entire genome. This approach allows the amplification
of DNA isolated from small cell colonies of putative somatic hybrids for rapid molecular confirmation of the hybrid status
of fusion products. 相似文献