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22.
Background
Association mapping using abundant single nucleotide polymorphisms is a powerful tool for identifying disease susceptibility genes for complex traits and exploring possible genetic diversity. Genotyping large numbers of SNPs individually is performed routinely but is cost prohibitive for large-scale genetic studies. DNA pooling is a reliable and cost-saving alternative genotyping method. However, no software has been developed for complete pooled-DNA analyses, including data standardization, allele frequency estimation, and single/multipoint DNA pooling association tests. This motivated the development of the software, 'PDA' (Pooled DNA Analyzer), to analyze pooled DNA data. 相似文献23.
24.
Acceptor specificity of the human leukocyte alpha3 fucosyltransferase: role of FucT-VII in the generation of selectin ligands 总被引:2,自引:2,他引:0
Britten CJ; van den Eijnden DH; McDowell W; Kelly VA; Witham SJ; Edbrooke MR; Bird MI; de Vries T; Smithers N 《Glycobiology》1998,8(4):321-327
The alpha3 fucosyltransferase, FucT-VII, is one of the key
glycosyltransferases involved in the biosynthesis of the sialyl Lewis X
(sLex) antigen on human leukocytes. The sialyl Lewis X antigen
(NeuAcalpha(2-3)Galbeta(1-4)[Fucalpha(1-3)]GlcNAc-R) is an essential
component of the recruitment of leukocytes to sites of inflammation,
mediating the primary interaction between circulating leukocytes and
activated endothelium. In order to characterize the enzymatic properties of
the leukocyte alpha3 fucosyltransferase FucT-VII, the enzyme has been
expressed in Trichoplusia ni insect cells. The enzyme is capable of
synthesizing both sLexand sialyl-dimeric-Lexstructures in vitro , from
3'-sialyl-lacNAc and VIM-2 structures, respectively, with only low levels
of fucose transfer observed to neutral or 3'-sulfated acceptors. Studies
using fucosylated NeuAcalpha(2-3)-(Galbeta(1- 4)GlcNAc)3-Me acceptors
demonstrate that FucT-VII is able to synthesize both di-fucosylated and
tri-fucosylated structures from mono- fucosylated precursors, but
preferentially fucosylates the distal GlcNAc within a polylactosamine
chain. Furthermore, the rate of fucosylation of the internal GlcNAc
residues is reduced once fucose has been added to the distal GlcNAc. These
results indicate that FucT-VII is capable of generating complex selectin
ligands, in vitro , however the order of fucose addition to the lactosamine
chain affects the rate of selectin ligand synthesis.
相似文献
25.
In spite of the increasing application of DNA fingerprinting to natural
populations and to the genetic identification of humans, explicit methods
for estimation of basic population genetic parameters from DNA
fingerprinting data have not been developed. Contributing to this omission
is the inability to determine, for multilocus fingerprinting probes,
relatively important genetic information, such as the number of loci, the
number of alleles, and the distribution of these alleles into specific
loci. One of the most useful genetic parameters that could be derived from
such data would be the average heterozygosity, which has traditionally been
employed to measure the level of genetic variation within populations and
to compare genetic variation among different loci. We derive here explicit
formulas for both the estimation of average heterozygosity at multiple
hypervariable loci and a maximum value for this estimate. These estimates
are based upon the DNA restriction-pattern matrices that are typical for
fingerprinting studies of humans and natural populations. For several
empirical data sets from our laboratory, estimates of average and maximal
heterozygosity are shown to be relatively close to each other. Furthermore,
variances of these statistics based on simulation studies are relatively
small. These observations, as well as consideration of the effect of
missing alleles and alternate numbers of loci, suggest that the average
heterozygosity can be accurately estimated using phenotypic DNA fingerprint
patterns, because this parameter is relatively insensitive to the lack of
certain genetic information.
相似文献
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