421 research outputs found
Development of a real-time RT-PCR and Reverse Line probe Hybridisation assay for the routine detection and genotyping of Noroviruses in Ireland
Antigen-Independent Selection of T15 Idiotype During B-Cell Ontogeny In Mice
Precursors of B cells capable of responding to a T-independent form of phosphorylcholine
(PC) in splenic focus assays were detected in the spleens of neonatal mice as early as 4 days
after birth. The earliest anti-PC B cells were T15-. T15+ foci-forming B cells were first
detected 6 days after birth and expanded rapidly to constitute greater than 80% of the total
PC-specific foci by day 10. Injection of heat-killed S. pneumoniae (R36A) into neonatal mice
resulted in priming of the antibody response to PC, with an idiotype profile reflecting that
of precursors of foci-forming B cells at the time of antigen administration. Priming of 2-dayold
mice with 2 X106 and 2 X107 R36A induced a five- and ten-fold increase in the antibody
response to phosphorylcholine 6 to 8 weeks later. However, only 10 to 15% of the serum
antibodies expressed the normally dominant T15 idiotype. Doses below 2 x105 R36A showed
no detectable priming activity. PC-specific hybridomas derived from mice injected with
2 X107 R36A 2 days after birth lacked the idiotypic and molecular characteristics typical of
T15+ antibodies. Antibodies to phosphorylcholine, raised by immunization of 6-week-old
mice are normally protective against pneumococcal infection. However, serum antibodies
from mice treated with R36A 2 days after birth and responding to phosphorylcholine
following challenge with R36A at 6 weeks of age failed to protect against deliberate infection
with virulent S. pneumoniae. These observations imply that the antigen phosphorylcholine
does not play a role in the selective expansion and dominant expression of the T15 idiotype
Activated α4 Integrins are Preferentially Expressed on Immature Thymocytes and Activated T Cells
We have identified a novel mAb, SG31, which recognizes the mouse integrin α4 subunit. Unlike the epitopes recognized by other anti-α4 antibodies, the SG31 epitope is expressed on subpopulations of thymocytes and peripheral T cells. After manganese ion, but not phorbol myristic acetate activation, the epitope is induced and expressed on the majority of peripheral T cells. These data suggest that the SG31 epitope is an activation epitope and that manganese ions activate α4 integrins by inducing a conformational change. Comparative flow cytometric analyses showed that the SG31 epitope as well as the epitope detected by other anti-α4 antibodies is expressed on all B lineage cells. In the T lineage, expression of the α4 integrins is down-regulated during thymocyte development. Although mature thymocytes still express the α4 integrins, they lose almost entirely the activation epitope recognized by SG31. In contrast, the most immature thymocytes express high levels of this epitope. In the periphery, SG31 epitope is expressed mostly by activated T cells, in contrast to the overall population of T cells that express the α4 integrins at homogenous levels. These results suggest that the activation of the α4 integrins is parallel to that of T cells
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An evaluation of the use and effectiveness of temporary sediment controls
Center for Research in Water Resource
Concordance rate between copy number variants detected using either high- or medium-density single nucleotide polymorphism genotype panels and the potential of imputing copy number variants from flanking high density single nucleotide polymorphism haplotypes in cattle
peer-reviewedBackground
The trading of individual animal genotype information often involves only the exchange of the called genotypes and not necessarily the additional information required to effectively call structural variants. The main aim here was to determine if it is possible to impute copy number variants (CNVs) using the flanking single nucleotide polymorphism (SNP) haplotype structure in cattle. While this objective was achieved using high-density genotype panels (i.e., 713,162 SNPs), a secondary objective investigated the concordance of CNVs called with this high-density genotype panel compared to CNVs called from a medium-density panel (i.e., 45,677 SNPs in the present study). This is the first study to compare CNVs called from high-density and medium-density SNP genotypes from the same animals. High (and medium-density) genotypes were available on 991 Holstein-Friesian, 1015 Charolais, and 1394 Limousin bulls. The concordance between CNVs called from the medium-density and high-density genotypes were calculated separately for each animal. A subset of CNVs which were called from the high-density genotypes was selected for imputation. Imputation was carried out separately for each breed using a set of high-density SNPs flanking the midpoint of each CNV. A CNV was deemed to be imputed correctly when the called copy number matched the imputed copy number.
Results
For 97.0% of CNVs called from the high-density genotypes, the corresponding genomic position on the medium-density of the animal did not contain a called CNV. The average accuracy of imputation for CNV deletions was 0.281, with a standard deviation of 0.286. The average accuracy of imputation of the CNV normal state, i.e. the absence of a CNV, was 0.982 with a standard deviation of 0.022. Two CNV duplications were imputed in the Charolais, a single CNV duplication in the Limousins, and a single CNV duplication in the Holstein-Friesians; in all cases the CNV duplications were incorrectly imputed.
Conclusion
The vast majority of CNVs called from the high-density genotypes were not detected using the medium-density genotypes. Furthermore, CNVs cannot be accurately predicted from flanking SNP haplotypes, at least based on the imputation algorithms routinely used in cattle, and using the SNPs currently available on the high-density genotype panel
A Developmental Bias in Reading Frame Usage by Human Fetal Thymic TCRBDJ Transcripts is not Present in Genomic TCRBDJ Rearrangements
We have previously reported that reading-frame usage and functional diversification is developmentally
regulated, with virtually all TCRB DJ mRNA transcripts using a single reading
frame at 8 weeks of gestational age, tapering to 50% by adult life. We used the polymerase
chain reaction to create genomic libraries of DJ rearrangements in the TCRB locus from thymuses
at 7.7, 10, and 16 weeks of gestational age, and from adult thymuses. Clones were randomly
picked and sequenced to determine junctional sequences and reading-frame
utilization. The resulting data address the hypothesis that cells bearing genomic joints in reading
frame one are preferentially selected during fetal life. This hypothesis predicts that reading-
frame bias would also be observed among genomic DJ joints. Instead, we observed
random utilization of the three possible D-region reading frames among genomic D1s1 =>
J1s1 joints during fetal life. Similar results were obtained at 7.7 weeks of gestational age in a
second thymus in which both RNA and DNA were simultaneously isolated and used to create
libraries of TCRBDJ transcripts or rearrangements. We conclude that reading-frame utilization
is random among genomic D1s1-JB1s1 rearrangements and that the preferential usage of
a single reading frame among mRNA transcripts of TCRB DJ transcripts is the result of preferential
transcription of genomic TCRB DJ joints in a single reading frame, or that TCRB DJ
transcripts have a longer half-life than transcripts in reading frames two or three
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