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61.
Background
As the use of microarray technology becomes more prevalent it is not unusual to find several laboratories employing the same microarray technology to identify genes related to the same condition in the same species. Although the experimental specifics are similar, typically a different list of statistically significant genes result from each data analysis. 相似文献62.
KADRI TALI MICHAEL F. FAY RICHARD M. BATEMAN 《Biological journal of the Linnean Society. Linnean Society of London》2006,87(1):13-25
Amplified fragment length polymorphism (AFLP) was used to characterize genetic diversity of the endangered Burnt Orchid, Neotinea (formerly Orchis ) ustulata . Fingerprinting of Estonian and British populations revealed surprisingly little genetic differentiation between populations but larger amounts of diversity within populations, especially in Britain. The resulting mean F st value of 0.51 is unusually high for an orchid species. Much of the variation follows a west–east cline across Europe, whereas the much-discussed early- and late-flowering taxa of N. ustulata are considered insufficiently distinct to be viewed as separate subspecies. The later flowering N. ustulata var. aestivalis probably evolved independently on two or three occasions, each time diverging from the earlier flowering nominate race. The identity of the genes underpinning phenology in the species, and the potential selective advantages of phenological divergence, merit further study. Overall genetic diversity within populations is sufficiently high to render impoverishment an unlikely cause of their recent, precipitous decline. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 13–25. 相似文献
63.
Phylogenetic utility of elongation factor-1 alpha in noctuoidea (Insecta: Lepidoptera): the limits of synonymous substitution 总被引:2,自引:1,他引:1
Mitchell A; Cho S; Regier JC; Mitter C; Poole RW; Matthews M 《Molecular biology and evolution》1997,14(4):381-390
To test its phylogenetic utility, nucleotide sequence variation in a
1,240-bp fragment of the elongation factor-1 alpha (EF-1 alpha) gene was
examined in 49 moth species representing the major groups of the
superfamily Noctuoidea. Both parsimony and distance analyses supported the
monophyly of nearly all groups for which there are clear morphological
synapomorphies. Clades of subfamily rank and lower, probably mid-Tertiary
and younger, were strongly supported. The third codon position contains 88%
of variable sites, and approaches saturation at approximately 20% sequence
divergence, possibly due to among-site rate heterogeneity and composition
bias; higher divergences occur only in association with shifts in
composition. Surprisingly, the few nonsynonymous changes appear no more
phylogenetically reliable than synonymous changes. Signal strength for
basal divergences is weak and fails to improve with character weighting;
thus, dense taxon sampling is probably needed for strong inference from
EF-1 alpha regarding deeper splits in Noctuoidea (probably early Tertiary).
EF-1 alpha synonymous changes show promise for phylogeny reconstruction
within Noctuidae and other groups of Tertiary age.
相似文献
64.
Human responses to propionic acid. I. Quantification of within- and between-participant variation in perception by normosmics and anosmics 总被引:4,自引:3,他引:1
The objective of this study was to fully characterize normosmic perception
of stimuli expected to cause widely varying degrees of olfactory and nasal
trigeminal stimulation and to directly evaluate the possible role of
olfactory nerve stimulation in nasal irritation sensitivity. During each of
four identical test sessions, four anosmic and 31 normosmic participants
were presented with a range of concentrations extending from peri-threshold
for normosmics to supra- threshold for anosmics. For each session, odor (O)
and nasal irritation (NI) sensitivities were summarized in terms of the
concentrations required to produce four sensation levels ('iso-response'
concentrations). Within-participant variation in these iso-response
concentrations was < 10-fold for 95% of normosmics, for both O and NI.
For O but not NI, these apparent fluctuations in sensitivity were largely
accounted for by the uncertainty surrounding the iso-response
concentrations calculated for each session. Anosmics exhibited minimal
within- and between-participant variation in NI and required, for all but
the highest perceptual level, a higher concentration than almost all
normosmics. Between-participant variation, expressed in terms of 90%
confidence interval widths, was approximately 0.5 log units for both O and
NI for the highest perceptual level, but increased to approximately 0.8 and
1.8 log units, respectively, for the lowest (peri- threshold) level. Our
findings suggest that: (i) most apparent variation over time in O
sensitivity is actually a reflection of the uncertainty surrounding
estimates of sensitivity obtained for each session; (ii) within- and
between-participant variation in O sensitivity is far less than is commonly
reported; and (iii) low to moderate levels of NI in normosmics are the
result of relatively weak trigeminal stimulation combined with much greater
olfactory activation.
相似文献
65.
The IgG1hybridoma antibody, 91.9H, was originally raised against sulfated
mucins isolated from normal human colonic mucosa. Previous studies have
shown that the 91.9H antigen is expressed on normal colonic epithelial
cells and the sulfomucins that they produce, but not in the normal small
intestine and stomach. Tissue-specific changes occur in 91.9H antigen
expression in disease: the antigen diminishes in colonic carcinomas,
whereas in regions of gastric mucosa showing intestinal metaplasia and in
gastric carcinomas, the antigen is expressed as a "neo-antigen." This
report is concerned with elucidation, by the neoglycolipid technology, of
the determinant recognized by antibody 91.9H using sulfated and sialyl
oligosaccharides of Lewisa(Lea) and Lextypes, and analogs that lack
sulfate, sialic acid, or fucose. Binding experiments with the lipid-linked
oligosaccharides immobilized on chromatograms or on microwells, and
inhibition of binding experiments with free oligosaccharides based on di-,
tri- and tetrasaccharide backbones, show that the 91.9H antigenic
determinant is based on a trisaccharide backbone, and consists of the
3'-sulfated Leatetrasaccharide sequence, which is a potent ligand for the
E- and L-selectins. The antibody gives a relatively low signal with the
3'-sulfated non-fucosylated backbone, and has no detectable cross- reaction
with the 3'-sulfated Lexisomer, nor with sialyl-Leaand - Lexanalogues.
Antibody 91.9H is a valuable addition, therefore, to the repertoire of
reagents for mapping details of the distribution, and determining the
relative importance of sulfated and sialyl oligosaccharides as ligands for
the selectins, in normal and pathological epithelia and endothelia.
相似文献
66.
Abstract Three habitats, each containing a different form (rainforest, coastal and dry tropics) of the twining vine Tinospora smilacina, and a fourth with two of these forms were routinely sampled between 1986 and 1989 for larvae of fruitpiercing moths, to ascertain spatial and temporal utilization of this plant. Othreis fullonia and Othreis materna occurred on all forms in all habitats, predominantly between November and March for the former and January to June for the latter. Although Rhytia cocalus utilized two forms of T. smilacina it preferred the rainforest habitat to which Othreis jordani and Khadira aurantia were essentially confined. While the degree of cohabitation between any two moth species was greatest in the drier inland habitat, where only O. materna and O. fullonia occurred during a limited season, there was considerable temporal separation of any two species utilizing T. smilacina in any habitat. Field and laboratory evaluation of alternative menisperm hosts suggested O. fullonia, O. jordani and K. aurantia were generalists while O. materna and R. cocalus confined their feeding to the genus Tinospora. The differential habitat affinities and host plant acceptance of these moths are pertinent to their variable seasonal activity, local importance and general pest status. 相似文献
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