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11.
Liliane?VenturaEmail author Gabriel?Torres?de Jesus Gunter?Camilo Dablas?de Oliveira Sidney?JF?Sousa 《Biomedical engineering online》2005,4(1):70
Background
The authors have developed a small portable device for the objective measurement of the transparency of corneas stored in preservative medium, for use by eye banks in evaluation prior to transplantation. 相似文献12.
alpha-Tocopherol and protein kinase C inhibition enhance platelet-derived nitric oxide release. 总被引:7,自引:0,他引:7
Platelet activation is tightly regulated by products of the endothelium and platelets including nitric oxide (NO). Excess vascular oxidative stress has been associated with impaired NO release, and antioxidant status has been shown to alter endothelium-derived NO bioactivity. Although physiological levels of a-tocopherol are known to inhibit platelet function, the effect of a-tocopherol on platelet NO release is unknown. Loading platelets with physiologic levels of a-tocopherol increased platelet NO production approximately 1.5-fold (Pa-tocopherol, platelet NO release increased 50% (Pa-Tocopherol-loaded platelets also produced 74% less superoxide as compared with control (Pa-tocopherol inhibited PKC-dependent eNOS phosphorylation as determined by immunoprecipitation. Lastly, platelets isolated from NOS3-deficient mice released 80% less superoxide as compared with control animals (P=0.011), and incubation of NOS III-deficient platelets with 500 mM a-tocopherol only caused a modest additional decrease in platelet superoxide release (NS). Thus, a-tocopherol appears to enhance platelet NO release both in vitro and in vivo through antioxidant- and PKC-dependent mechanisms. 相似文献
13.
JF Yuan SJ Zhang O Jafer RA Furlong OE Chausiaux CA Sargent GH Zhang NA Affara 《BMC microbiology》2009,9(1):246
Background
Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult. 相似文献14.
Background
The past several years have seen a flurry of papers seeking to clarify the utility and limits of DNA barcoding, particularly in areas such as species discovery and paralogy due to nuclear pseudogenes. Heteroplasmy, the coexistence of multiple mitochondrial haplotypes in a single organism, has been cited as a potentially serious problem for DNA barcoding but its effect on identification accuracy has not been tested. In addition, few studies of barcoding have tested a large group of closely-related species with a well-established morphological taxonomy. In this study we examine both of these issues, by densely sampling the Hawaiian Hylaeus bee radiation. 相似文献15.
The murid rodent subfamily Sigmodontinae contains 79 genera which are
distributed throughout the New World. The time of arrival of the first
sigmodontines in South America and the estimated divergence time(s) of the
different lineages of South American sigmodontines have been controversial
due to the lack of a good fossil record and the immense number of extant
species. The "early-arrival hypothesis" states that the sigmodontines must
have arrived in South America no later than the early Miocene, at least 20
MYA, in order to account for their vast present-day diversity, whereas the
"late-arrival hypothesis" includes the sigmodontines as part of the
Plio-Pleistocene Great American Interchange, which occurred approximately
3.5 MYA. The phylogenetic relationships among 33 of these genera were
reconstructed using mitochondrial DNA (mtDNA) sequence data from the ND3,
ND4L, arginine tRNA, and ND4 genes, which we show to be evolving at the
same rate. A molecular clock was calibrated for these genes using published
fossil dates, and the genetic distances were estimated from the DNA
sequences in this study. The molecular clock was used to estimate the dates
of the South American sigmodontine origin and the main sigmodontine
radiation in order to evaluate the "early-" and "late-arrival" scenarios.
We estimate the time of the sigmodontine invasion of South America as
between approximately 5 and 9 MYA, supporting neither of the scenarios but
suggesting two possible models in which the invading lineage was either (1)
ancestral to the oryzomyines, akodonts, and phyllotines or (2) ancestral to
the akodonts and phyllotines and accompanied by the oryzomyines. The
sigmodontine invasion of South America provides an example of the advantage
afforded to a lineage by the fortuitous invasion of a previously
unexploited habitat, in this case an entire continent.
相似文献
16.
Background
Host parasitism by Trichomonas vaginalis is complex. Adherence to vaginal epithelial cells (VECs) is mediated by surface proteins. We showed before that antisense down-regulation of expression of adhesin AP65 decreased amounts of protein, which lowered levels of T. vaginalis adherence to VECs. We now perform antisense down-regulation of expression of the ap33 gene to evaluate and confirm a role for AP33 in adherence by T. vaginalis. We also used an established transfection system for heterologous expression of AP33 in T. foetus as an additional confirmatory approach. 相似文献17.
18.
Previously, treatment of Tamm-Horsfall glycoprotein (THp) from different
donors with endo-beta-galactosidase has been shown to liberate a tetra- and
a Sd(a)-active pentasaccharide, concluding the presence of N-linked
carbohydrate chains containing additional N - acetyllactosamine units.
These type of oligosaccharides were not found in a detailed structure
elucidation of the carbohydrate moiety of THp of one male donor, suggesting
a donor-specific feature for these type of structures. Therefore, THp was
isolated from four healthy male donors and each subjected to
endo-beta-galactosidase treatment in order to release these tetra- and
Sd(a)-active pentasaccharide. Differences were observed in the total amount
of released tetra- and Sda-active pentasaccharide of the used donors (42,
470, 478, 718 microg/100 mg THp), indicating that the presence of repeating
N-acetyllactosamine units incorporated into the N-glycan moiety of THp is
donor specific. Furthermore, a higher expression of the Sd(a) determinant
on antennae which display N-acetyllactosamine elongation was observed,
suggesting a better accessibility for the
beta-N-acetylgalactosaminyltransferase. In order to characterize the
N-glycans containing repeating N- acetyllactosamine units, carbohydrate
chains were enzymatically released from THp and isolated. The
tetraantennary fraction, which accounts for more than 33% of the total
carbohydrate moiety of THp, was used to isolate oligosaccharides containing
additional N - acetyllactosamine units. Five N-linked tetraantennary
oligosaccharides containing a repeating N-acetyllactosamine unit were
identified, varying from structures bearing four Sd(a) determinants to
structures containing no Sd(a) determinant (see below). One compound was
used in order to specify the branch location of the additional N-
acetyllactosamine unit, and it appeared that only the Gal-6' and Gal-8'
residues were occupied by a repeating N -acetyllactosamine unit.
相似文献
19.
The sequences of the 5' long-terminal repeat (LTR) and adjacent leader
regions of 27 full-length copia elements isolated from natural populations
of Drosophila melanogaster, D. simulans, and D. mauritiana are presented.
Phylogenetic analyses indicate that although D. melanogaster copia elements
are distinct from those of D. simulans and D. mauritiana, the elements of
these latter two species are not distinguishable from one another. LTRs and
adjacent 5' leader regions of elements isolated from D. simulans and D.
mauritiana are structurally similar to one another and carry substantial
deletional variation mapping to regions previously identified as being of
potential importance for copia expression.
相似文献
20.
Wingfield BD; Grant WS; Wolfaardt JF; Wingfield MJ 《Molecular biology and evolution》1994,11(3):376-383
The genus Ceratocystis sensu stricto includes important fungal pathogens of
woody and herbaceous plants. This genus is distinguished from species in
Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore
shape has been used extensively in delineating Ceratocystis taxa, which
show a large variety of ascospore shapes. Sequence analysis of one region
of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA
subunit showed that there was a majority of multiple substitutions at
nucleotide sites and that there was a low transition/transversion ratio, T
= 0.72. Both of these results suggest that these are well established, old
species. Ascospore morphology, for the most part, was not congruent with
the molecular phylogeny, and the use of morphological characters may be
misleading in the taxonomy of these species.
相似文献