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1.
Contents Volume 11 1990 相似文献
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J L Omdahl K Wilson H Swerdlow W J Driscoll 《Archives of biochemistry and biophysics》1992,293(2):213-218
Porcine renodoxon is a kidney mitochondrial iron-sulfur protein (ISP) that functions to transfer electron to cytochromes P450 of the vitamin D pathway. A full-length cDNA clone to porcine renodoxin was isolated in the current investigation and used to study the protein's primary structure and immunological properties. The cysteine ligands for the iron-sulfur center, and the surface protein-binding and phosphorylation sites occupied identical positions in both porcine renodoxin and bovine adrenodoxin. Furthermore, porcine renodoxin was functionally indistinguishable from bovine adrenodoxin and the mature forms of both proteins had the same encoded length and shared approximately 91% sequence similarity. A synthetic peptide to the surface protein-binding region was used to demonstrate the antigenicity of the domain in both the porcine and the bovine ISPs. However, porcine renodoxin displayed only limited immunological identity to other regions of bovine adrenodoxin as measured by competitive enzyme-linked immunosorbent assay. Part of this immunological distinction was attributed to the COOH-terminal processing of porcine renodoxin, an action which negated expression of a COOH-terminal antigenic site that is present in bovine adrenodoxin. Other antigenic differences were linked to charged-residue substitutions that were located in predicted surface domains. The highest frequency of surface-residue substitutions in ferredoxin proteins was predicted for porcine renodoxin, which could provide a basis for understanding why the pig protein appears more antigenically divergent than other ferredoxins. 相似文献
4.
Monica Driscoll 《Developmental neurobiology》1992,23(9):1327-1351
In C. elegans, cell death can be readily studied at the cellular, genetic, and molecular levels. Two types of death have been characterized in this nematode: (1) programmed cell death, which occurs as a normal component in development; and (2) pathological cell death which occurs aberrantly as a consequence of mutation. Analysis of mutations that disrupt programmed cell death in various ways has defined a genetic pathway for programmed cell death which includes genes that perform such functions as the determination of which cells die, the execution of cell death, the engulfment of cell corpses, and the digestion of DNA from dead cells. Molecular analysis is providing insightinto the nature of the molecules that function in these aspects of programmed cell death. Characterization of some genes that mutate to induce abnormal cell death has defined a novel gene family called degenerins that encode putative membrane proteins. Dominant alleles of at least two degenerin genes, mec-4 and deg-1, can cause cellular swelling and late onset neurodegeneration of specific groups of cells. © 1992 John Wiley & Sons, Inc. 相似文献
5.
Aoife M. O’Mahony Julien Ogier Raphael Darcy John F. Cryan Caitriona M. O’Driscoll 《PloS one》2013,8(6)
Optimising non-viral vectors for neuronal siRNA delivery presents a significant challenge. Here, we investigate a co-formulation, consisting of two amphiphilic cyclodextrins (CDs), one cationic and the other PEGylated, which were blended together for siRNA delivery to a neuronal cell culture model. Co-formulated CD-siRNA complexes were characterised in terms of size, charge and morphology. Stability in salt and serum was also examined. Uptake was determined by flow cytometry and toxicity was measured by MTT assay. Knockdown of a luciferase reporter gene was used as a measure of gene silencing efficiency. Incorporation of a PEGylated CD in the formulation had significant effects on the physical and biological properties of CD.siRNA complexes. Co-formulated complexes exhibited a lower surface charge and greater stability in a high salt environment. However, the inclusion of the PEGylated CD also dramatically reduced gene silencing efficiency due to its effects on neuronal uptake. The co-formulation strategy for cationic and PEGylated CDs improved the stability of the CD.siRNA delivery systems, although knockdown efficiency was impaired. Future work will focus on the addition of targeting ligands to the co-formulated complexes to restore transfection capabilities. 相似文献
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The Biogeochemistry of Carbon at Hubbard Brook 总被引:6,自引:1,他引:5
T. J. Fahey T. G. Siccama C. T. Driscoll G. E. Likens J. Campbell C. E. Johnson J. J. Battles J. D. Aber J. J. Cole M. C. Fisk P. M. Groffman S. P. Hamburg R. T. Holmes P. A. Schwarz R. D. Yanai 《Biogeochemistry》2005,75(1):109-176
The biogeochemical behavior of carbon in the forested watersheds of the Hubbard Brook Experimental Forest (HBEF) was analyzed
in long-term studies. The largest pools of C in the reference watershed (W6) reside in mineral soil organic matter (43% of
total ecosystem C) and living biomass (40.5%), with the remainder in surface detritus (14.5%). Repeated sampling indicated
that none of these pools was changing significantly in the late-1990s, although high spatial variability precluded the detection
of small changes in the soil organic matter pools, which are large; hence, net ecosystem productivity (NEP) in this 2nd growth
forest was near zero (± about 20 g C/m2-yr) and probably similar in magnitude to fluvial export of organic C. Aboveground net primary productivity (ANPP) of the
forest declined by 24% between the late-1950s (462 g C/m2-yr) and the late-1990s (354 g C/m2-yr), illustrating age-related decline in forest NPP, effects of multiple stresses and unusual tree mortality, or both. Application
of the simulation model PnET-II predicted 14% higher ANPP than was observed for 1996–1997, probably reflecting some unknown
stresses. Fine litterfall flux (171 g C/m2-yr) has not changed much since the late-1960s. Because of high annual variation, C flux in woody litterfall (including tree
mortality) was not tightly constrained but averaged about 90 g C/m2-yr. Carbon flux to soil organic matter in root turnover (128 g C/m2-yr) was only about half as large as aboveground detritus. Balancing the soil C budget requires that large amounts of C (80 g C/m2-yr) were transported from roots to rhizosphere carbon flux. Total soil respiration (TSR) ranged from 540 to 800 g C/m2-yr across eight stands and decreased with increasing elevation within the northern hardwood forest near W6. The watershed-wide
TSR was estimated as 660 g C/m2-yr. Empirical measurements indicated that 58% of TSR occurred in the surface organic horizons and that root respiration comprised
about 40% of TSR, most of the rest being microbial. Carbon flux directly associated with other heterotrophs in the HBEF was
minor; for example, we estimated respiration of soil microarthropods, rodents, birds and moose at about 3, 5, 1 and 0.8 g C/m2-yr, respectively, or in total less than 2% of NPP. Hence, the effects of other heterotrophs on C flux were primarily indirect,
with the exception of occasional irruptions of folivorous insects. Hydrologic fluxes of C were significant in the watershed
C budget, especially in comparison with NEP. Although atmospheric inputs (1.7 g C/m2-yr) and streamflow outputs (2.7 g C/m2-yr) were small, larger quantities of C were transported within the ecosystem and a more substantial fraction of dissolved
C was transported from the soil as inorganic C and evaded from the stream as CO2 (4.0 g C/m2-yr). Carbon pools and fluxes change rapidly in response to catastrophic disturbances such as forest harvest or major windthrow
events. These changes are dominated by living vegetation and dead wood pools, including roots. If biomass removal does not
accompany large-scale disturbance, the ecosystem is a large net source of C to the atmosphere (500–1200 g C/m2-yr) for about a decade following disturbance and becomes a net sink about 15–20 years after disturbance; it remains a net
sink of about 200–300 g C/m2-yr for about 40 years before rapidly approaching steady state. Shifts in NPP and NEP associated with common small-scale or
diffuse forest disturbances (e.g., forest declines, pathogen irruptions, ice storms) are brief and much less dramatic. Spatial
and temporal patterns in C pools and fluxes in the mature forest at the HBEF reflect variation in environmental factors. Temperature
and growing-season length undoubtedly constrain C fluxes at the HBEF; however, temperature effects on leaf respiration may
largely offset the effects of growing season length on photosynthesis. Occasional severe droughts also affect C flux by reducing
both photosynthesis and soil respiration. In younger stands nutrient availability strongly limits NPP, but the role of soil
nutrient availability in limiting C flux in the mature forest is not known. A portion of the elevational variation of ANPP
within the HBEF probably is associated with soil resource limitation; moreover, sites on more fertile soils exhibit 20–25%
higher biomass and ANPP than the forest-wide average. Several prominent biotic influences on C pools and fluxes also are clear.
Biomass and NPP of both the young and mature forest depend upon tree species composition as well as environment. Similarly,
litter decay differs among tree species and forest types, and forest floor C accumulation is twice as great in the spruce–fir–birch
forests at higher elevations than in the northern hardwood forests, partly because of inherently slow litter decay and partly
because of cold temperatures. This contributes to spatial patterns in soil solution and streamwater dissolved organic carbon
across the Hubbard Brook Valley. Wood decay varies markedly both among species and within species because of biochemical differences
and probably differences in the decay fungi colonizing wood. Although C biogeochemistry at the HBEF is representative of mountainous
terrain in the region, other sites will depart from the patterns described at the HBEF, due to differences in site history,
especially agricultural use and fires during earlier logging periods. Our understanding of the C cycle in northern hardwood
forests is most limited in the area of soil pool size changes, woody litter deposition and rhizosphere C flux processes. 相似文献
9.
Woojin M. Han Su-Jin Heo Tristan P. Driscoll Lachlan J. Smith Robert L. Mauck Dawn M. Elliott 《Biophysical journal》2013
Mechanical deformation applied at the joint or tissue level is transmitted through the macroscale extracellular matrix to the microscale local matrix, where it is transduced to cells within these tissues and modulates tissue growth, maintenance, and repair. The objective of this study was to investigate how applied tissue strain is transferred through the local matrix to the cell and nucleus in meniscus, tendon, and the annulus fibrosus, as well as in stem cell-seeded scaffolds engineered to reproduce the organized microstructure of these native tissues. To carry out this study, we developed a custom confocal microscope-mounted tensile testing device and simultaneously monitored strain across multiple length scales. Results showed that mean strain was heterogeneous and significantly attenuated, but coordinated, at the local matrix level in native tissues (35–70% strain attenuation). Conversely, freshly seeded scaffolds exhibited very direct and uniform strain transfer from the tissue to the local matrix level (15–25% strain attenuation). In addition, strain transfer from local matrix to cells and nuclei was dependent on fiber orientation and tissue type. Histological analysis suggested that different domains exist within these fibrous tissues, with most of the tissue being fibrous, characterized by an aligned collagen structure and elongated cells, and other regions being proteoglycan (PG)-rich, characterized by a dense accumulation of PGs and rounder cells. In meniscus, the observed heterogeneity in strain transfer correlated strongly with cellular morphology, where rounder cells located in PG-rich microdomains were shielded from deformation, while elongated cells in fibrous microdomains deformed readily. Collectively, these findings suggest that different tissues utilize distinct strain-attenuating mechanisms according to their unique structure and cellular phenotype, and these differences likely alter the local biologic response of such tissues and constructs in response to mechanical perturbation. 相似文献
10.
Mark J. Mitton-Fry Steven J. Brickner Judith C. Hamel Lori Brennan Jeffrey M. Casavant Michael Chen Tao Chen Xiaoyuan Ding James Driscoll Joel Hardink Thuy Hoang Erbing Hua Michael D. Huband Meghan Maloney Anthony Marfat Sandra P. McCurdy Dale McLeod Michael Plotkin Christopher Zook 《Bioorganic & medicinal chemistry letters》2013,23(10):2955-2961
A structurally novel set of inhibitors of bacterial type II topoisomerases with potent in vitro and in vivo antibacterial activity was developed. Dual-targeting ability, hERG inhibition, and pharmacokinetic properties were also assessed. 相似文献