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Al-Mssallem IS, Hu S, Zhang X, Lin Q, Liu W, Tan J, Yu X, Liu J, Pan L, Zhang T, Yin Y, Xin C, Wu H, Zhang G, Ba Abdullah MM, Huang D, Fang Y, Alnakhli YO, Jia S, Yin A, Alhuzimi EM, Alsaihati BA, Al-Owayyed SA, Zhao D, Zhang S, Al-Otaibi NA, Sun G, Majrashi MA, Li F, Tala, Wang J, Yun Q, Alnassar NA, Wang L, Yang M, Al-Jelaify RF, Liu K, Gao S, Chen K, Alkhaldi SR, Liu G, Zhang M, Guo H, Yu J. Genome sequence of the date palm Phoenix dactylifera L. Nat Commun 2013; 4:2274. [PMID: 23917264 DOI: 10.1038/ncomms3274] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/09/2013] [Indexed: 02/03/2023] Open
Abstract
Date palm (Phoenix dactylifera L.) is a cultivated woody plant species with agricultural and economic importance. Here we report a genome assembly for an elite variety (Khalas), which is 605.4 Mb in size and covers >90% of the genome (~671 Mb) and >96% of its genes (~41,660 genes). Genomic sequence analysis demonstrates that P. dactylifera experienced a clear genome-wide duplication after either ancient whole genome duplications or massive segmental duplications. Genetic diversity analysis indicates that its stress resistance and sugar metabolism-related genes tend to be enriched in the chromosomal regions where the density of single-nucleotide polymorphisms is relatively low. Using transcriptomic data, we also illustrate the date palm’s unique sugar metabolism that underlies fruit development and ripening. Our large-scale genomic and transcriptomic data pave the way for further genomic studies not only on P. dactylifera but also other Arecaceae plants. The date palm is one of the most economically important plants of the palm family. Here, the authors present a high-quality genome assembly of the date palm Phoenix dactylifera, and reveal insights into the unique sugar metabolism underlying fruit ripening.
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Wang Y, Chen X, Tsai S, Thomas A, Shizuru JA, Cao TM. Fine mapping of the Bmgr5 quantitative trait locus for allogeneic bone marrow engraftment in mice. Immunogenetics 2013; 65:585-96. [PMID: 23666360 PMCID: PMC3713196 DOI: 10.1007/s00251-013-0709-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 04/26/2013] [Indexed: 01/04/2023]
Abstract
To identify novel mechanisms regulating allogeneic hematopoietic cell engraftment, we used forward genetics and previously described identification, in mice, of a bone marrow (BM) engraftment quantitative trait locus (QTL), termed Bmgr5. This QTL confers dominant and large allele effects for engraftment susceptibility. It was localized to chromosome 16 by quantitative genetic techniques in a segregating backcross bred from susceptible BALB.K and resistant B10.BR mice. We now report verification of the Bmgr5 QTL using reciprocal chromosome 16 consomic strains. The BM engraftment phenotype in these consomic mice shows that Bmgr5 susceptibility alleles are not only sufficient but also indispensable for conferring permissiveness for allogeneic BM engraftment. Using panels of congenic mice, we resolved the Bmgr5 QTL into two separate subloci, termed Bmgr5a (Chr16:14.6-15.8 Mb) and Bmgr5b (Chr16:15.8-17.6 Mb), each conferring permissiveness for the engraftment phenotype and both fine mapped to an interval amenable to positional cloning. Candidate Bmgr5 genes were then prioritized using whole exome DNA sequencing and microarray gene expression data. Further studies are warranted to elucidate the genetic interaction between the Bmgr5a and Bmgr5b QTL and identify causative genes and underlying gene variants. This may lead to new approaches for overcoming the problem of graft rejection in clinical hematopoietic cell transplantation.
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Affiliation(s)
- Yuanyuan Wang
- Blood and Marrow Transplantation Program, Department of Medicine, University of Utah, Salt Lake City, UT
| | - Xinjian Chen
- Department of Pathology, University of Utah, Salt Lake City, UT
| | - Schickwann Tsai
- Blood and Marrow Transplantation Program, Department of Medicine, University of Utah, Salt Lake City, UT
| | - Alun Thomas
- Department of Biomedical Informatics, University of Utah, Salt Lake City, UT
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT
| | - Judith A. Shizuru
- Division of Blood and Marrow Transplantation, Department of Medicine, Stanford University School of Medicine, Stanford, CA
| | - Thai M. Cao
- Blood and Marrow Transplantation Program, Department of Medicine, University of Utah, Salt Lake City, UT
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT
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Abstract
The nonobese diabetic (NOD) mouse has provided an important animal model for studying the mechanism and genetics of type 1 diabetes over the past 30 years. Arguably, the bio-breeding (BB) rat model may be an even closer phenotypic mimic of the typical human disease. A large number of distinct genetic traits which influence diabetes development have been defined through an extraordinary effort, most conspicuously in the mouse model. However, in both NOD and BB models the lack of availability of robust means for experimental genetic manipulation has restricted our understanding of the mechanisms underlying this spontaneous autoimmune disease. Recent developments in the derivation of embryonic stem (ES) cells have the potential to transform this picture. We argue here that targeting of NOD strain ES cells can bring much needed certainty to our present understanding of the genetics of type 1 diabetes in the NOD mouse. In addition, ES cells can play important roles in the future, in both the NOD mouse and BB rat models, through the generation of new tools to investigate the mechanisms by which genetic variation acts to promote diabetes.
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Affiliation(s)
- Nick Holmes
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
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Hadsell DL, Wei J, Olea W, Hadsell LA, Renwick A, Thomson PC, Shariflou M, Williamson P. In silico QTL mapping of maternal nurturing ability with the mouse diversity panel. Physiol Genomics 2012; 44:787-98. [PMID: 22759921 DOI: 10.1152/physiolgenomics.00159.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Significant variation exists for maternal nurturing ability in inbred mice. Although classical mapping approaches have identified quantitative trait loci (QTL) that may account for this variation, the underlying genes are unknown. In this study, lactation performance data among the mouse diversity panel were used to map genomic regions associated with this variation. Females from each of 32 inbred strains (n = 8-19 dams/strain) were studied during the first 8 days of lactation by allowing them to raise weight- and size-normalized cross-foster litters (10 pups/litter). Average daily weight gain (ADG) of litters served as the primary indicator of milk production. The number of pups successfully reared to 8 days (PNUM8) also served as a related indicator of maternal performance. Initial haplotype association analysis using a Bonferroni-corrected, genome-wide threshold revealed 10 and 15 associations encompassing 11 and 13 genes for ADG and PNUM8, respectively. The most significant of these associated haplotype blocks were found on MMU 8, 11, and 19 and contained the genes Nr3c2, Egfr, Sec61g, and Gnaq. Lastly, two haplotype blocks on MMU9 were detected in association with PNUM8. These overlapped with the previously described maternal performance QTL, Neogq1. These results suggest that the application of in silico QTL mapping is a useful tool in discovering the presence of novel candidate genes involved in determining lactation capacity in mice.
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Affiliation(s)
- D L Hadsell
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030-2600, USA.
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Yang HS, Shimomura K, Vitaterna MH, Turek FW. High-resolution mapping of a novel genetic locus regulating voluntary physical activity in mice. Genes Brain Behav 2011; 11:113-24. [PMID: 21978078 DOI: 10.1111/j.1601-183x.2011.00737.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Both human beings and animals exhibit substantial inter-individual variation in voluntary physical activity, and evidence indicates that a significant component of this variation is because of genetic factors. However, little is known of the genetic basis underlying central regulation of voluntary physical activity in mammals. In this study, using an F(2) intercross population and interval-specific congenic strains (ISCS) derived from the C57BL/6J strain and a chromosome 13 substitution strain, C57BL/6J-Chr13A/J/NA/J, we identified a 3.76-Mb interval on chromosome 13 containing 25 genes with a significant impact on daily voluntary wheel running activity in mice. Brain expression and polymorphisms between the C57BL/6J and A/J strains were examined to prioritize candidate genes. As the dopaminergic pathway regulates motor movement and motivational behaviors, we tested its function by examining cocaine-induced locomotor responses in ISCS with different levels of activity. The low-activity ISCS exhibited a significantly higher response to acute cocaine administration than the high-activity ISCS. Expression analysis of key dopamine-related genes (dopamine transporter and D1, D2, D3, D4 and D5 receptors) revealed that expression of D1 receptor was higher in the low-activity ISCS than in the high-activity ISCS in both the dorsal striatum and nucleus accumbens. Pathway analysis implicated Tcfap2a, a gene found within the 3.76-Mb interval, involved in the D1 receptor pathway. Using a luciferase reporter assay, we confirmed that the transcriptional factor, Tcfap2a, regulates the promoter activity of the D1 receptor gene. Thus, Tcfap2a is proposed as a candidate genetic regulator of the level of voluntary physical activity through its influence on a dopaminergic pathway.
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Affiliation(s)
- H S Yang
- Center for Sleep and Circadian Biology, Northwestern University, Evanston, IL 60208-3520, USA
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Goodhead I, Archibald A, Amwayi P, Brass A, Gibson J, Hall N, Hughes MA, Limo M, Iraqi F, Kemp SJ, Noyes HA. A comprehensive genetic analysis of candidate genes regulating response to Trypanosoma congolense infection in mice. PLoS Negl Trop Dis 2010; 4:e880. [PMID: 21085469 PMCID: PMC2976683 DOI: 10.1371/journal.pntd.0000880] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 10/12/2010] [Indexed: 02/04/2023] Open
Abstract
Background African trypanosomes are protozoan parasites that cause “sleeping sickness” in humans and a similar disease in livestock. Trypanosomes also infect laboratory mice and three major quantitative trait loci (QTL) that regulate survival time after infection with T. congolense have been identified in two independent crosses between susceptible A/J and BALB/c mice, and the resistant C57BL/6. These were designated Tir1, Tir2 and Tir3 for Trypanosoma infection response, and range in size from 0.9–12 cM. Principal Findings Mapping loci regulating survival time after T. congolense infection in an additional cross revealed that susceptible C3H/HeJ mice have alleles that reduce survival time after infection at Tir1 and Tir3 QTL, but not at Tir2. Next-generation resequencing of a 6.2 Mbp region of mouse chromosome 17, which includes Tir1, identified 1,632 common single nucleotide polymorphisms (SNP) including a probably damaging non-synonymous SNP in Pram1 (PML-RAR alpha-regulated adaptor molecule 1), which was the most plausible candidate QTL gene in Tir1. Genome-wide comparative genomic hybridisation identified 12 loci with copy number variants (CNV) that correlate with differential gene expression, including Cd244 (natural killer cell receptor 2B4), which lies close to the peak of Tir3c and has gene expression that correlates with CNV and phenotype, making it a strong candidate QTL gene at this locus. Conclusions By systematically combining next-generation DNA capture and sequencing, array-based comparative genomic hybridisation (aCGH), gene expression data and SNP annotation we have developed a strategy that can generate a short list of polymorphisms in candidate QTL genes that can be functionally tested. About one-third of cattle in sub-Saharan Africa are at risk of contracting “Nagana”—a disease caused by Trypanosoma parasites similar to those that cause human “Sleeping Sickness.” Laboratory mice can also be infected by trypanosomes, and different mouse breeds show varying levels of susceptibility to infection, similar to what is seen between different breeds of cattle. Survival time after infection is controlled by the underlying genetics of the mouse breed, and previous studies have localised three genomic regions that regulate this trait. These three “Quantitative Trait Loci” (QTL), which have been called Tir1, Tir2 and Tir3 (for Trypanosoma Infection Response 1–3) are well defined, but nevertheless still contain over one thousand genes, any number of which may be influencing survival. This study has aimed to identify the specific differences associated with genes that are controlling mouse survival after T. congolense infection. We have applied a series of analyses to existing datasets, and combined them with novel sequencing, and other genetic data to create short lists of genes that share polymorphisms across susceptible mouse breeds, including two promising “candidate genes”: Pram1 at Tir1 and Cd244 at Tir3. These genes can now be tested to confirm their effect on response to trypanosome infection.
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Affiliation(s)
- Ian Goodhead
- Centre for Genomic Research, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Alan Archibald
- The Roslin Institute, University of Edinburgh, Roslin, United Kingdom
| | - Peris Amwayi
- International Livestock Research Institute, Nairobi, Kenya
| | - Andy Brass
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
- School of Computer Science, University of Manchester, Manchester, United Kingdom
| | - John Gibson
- International Livestock Research Institute, Nairobi, Kenya
| | - Neil Hall
- Centre for Genomic Research, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Margaret A. Hughes
- Centre for Genomic Research, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Moses Limo
- Egerton University, Njoro, Nakuru, Kenya
| | - Fuad Iraqi
- International Livestock Research Institute, Nairobi, Kenya
| | - Stephen J. Kemp
- Centre for Genomic Research, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
- International Livestock Research Institute, Nairobi, Kenya
| | - Harry A. Noyes
- Centre for Genomic Research, School of Biological Sciences, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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Irie J, Reck B, Wu Y, Wicker LS, Howlett S, Rainbow D, Feingold E, Ridgway WM. Genome-wide microarray expression analysis of CD4+ T Cells from nonobese diabetic congenic mice identifies Cd55 (Daf1) and Acadl as candidate genes for type 1 diabetes. J Immunol 2008; 180:1071-9. [PMID: 18178847 DOI: 10.4049/jimmunol.180.2.1071] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
NOD.Idd3/5 congenic mice have insulin-dependent diabetes (Idd) regions on chromosomes 1 (Idd5) and 3 (Idd3) derived from the nondiabetic strains B10 and B6, respectively. NOD.Idd3/5 mice are almost completely protected from type 1 diabetes (T1D) but the genes within Idd3 and Idd5 responsible for the disease-altering phenotype have been only partially characterized. To test the hypothesis that candidate Idd genes can be identified by differential gene expression between activated CD4+ T cells from the diabetes-susceptible NOD strain and the diabetes-resistant NOD.Idd3/5 congenic strain, genome-wide microarray expression analysis was performed using an empirical Bayes method. Remarkably, 16 of the 20 most differentially expressed genes were located in the introgressed regions on chromosomes 1 and 3, validating our initial hypothesis. The two genes with the greatest differential RNA expression on chromosome 1 were those encoding decay-accelerating factor (DAF, also known as CD55) and acyl-coenzyme A dehydrogenase, long chain, which are located in the Idd5.4 and Idd5.3 regions, respectively. Neither gene has been implicated previously in the pathogenesis of T1D. In the case of DAF, differential expression of mRNA was extended to the protein level; NOD CD4+ T cells expressed higher levels of cell surface DAF compared with NOD.Idd3/5 CD4+ T cells following activation with anti-CD3 and -CD28. DAF up-regulation was IL-4 dependent and blocked under Th1 conditions. These results validate the approach of using congenic mice together with genome-wide analysis of tissue-specific gene expression to identify novel candidate genes in T1D.
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Affiliation(s)
- Junichiro Irie
- Division of Rheumatology and Immunology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
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Jawad M, Cole C, Zanker A, Giotopoulos G, Fitch S, Talbot CJ, Plumb M. QTL analyses of lineage-negative mouse bone marrow cells labeled with Sca-1 and c-Kit. Mamm Genome 2008; 19:190-8. [PMID: 18288524 DOI: 10.1007/s00335-008-9097-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 01/14/2008] [Indexed: 10/22/2022]
Abstract
Differences in the number of functionally and/or phenotypically defined bone marrow cells in inbred mouse strains have been exploited to map quantitative trait loci (QTL) that determine the variation in cell frequency. To extend this approach to the differences in the stem/progenitor cell compartment in CBA/H and C57BL/6 mice, we have exploited the resolution of flow cytometry and the power of QTL analyses in 124 F(2) mice to analyze lineage-negative (Lin(-)) bone marrow cells according to the intensity of labeling with Sca-1 and c-Kit. In the Lin(-) Sca-1(+) c-Kit(+) enriched population, six QTL were identified: one significant and five suggestive. Whereas previous in vitro clonogenic, LTC-IC, day 35 CAFC, and flow cytometry each identified different QTL, our approach identified the same or very similar QTL at all three loci (chromosomes 1, 17, and 18) as well as QTL on chromosomes 6 and 10. In silico analyses implicate hematopoietic stem cell homing involving Cxcr4 and Cxcl12 as being the determining pathway. The mapping of the same or very similar QTL in independent studies using different assay(s) suggests a common genetic determinant, and thus reinforces the biological and genetic significance of the QTL. These data also suggest that mouse bone marrow cell subpopulations can be functionally, phenotypically, and genetically defined.
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Bernichtein S, Petretto E, Jamieson S, Goel A, Aitman TJ, Mangion JM, Huhtaniemi IT. Adrenal gland tumorigenesis after gonadectomy in mice is a complex genetic trait driven by epistatic loci. Endocrinology 2008; 149:651-61. [PMID: 18006632 PMCID: PMC2556873 DOI: 10.1210/en.2007-0925] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Postgonadectomy adrenocortical tumorigenesis is a strain-specific phenomenon in inbred mice, assumed to be caused by elevated LH secretion and subsequent ectopic LH receptor (LHR) overexpression in adrenal gland. However, the molecular mechanisms of this cascade of events remain unknown. In this study, we took advantage of the mouse strain dependency of the phenotype to unravel its genetic basis. Our results present the first genome-wide screening related to this pathology in two independent F2 and backcross populations generated between the neoplastic DBA/2J and the nonsusceptible C57BL/6J strains. Surprisingly, the postgonadectomy elevation of serum LH was followed by similar up-regulation of adrenal LHR expression in both parental strains and their crosses, irrespective of their tumor status, indicating that it is not the immediate cause of the tumorigenesis. Linkage analysis revealed one major significant locus for the tumorigenesis on chromosome 8, modulated by epistasis with another quantitative trait locus on chromosome 18. Weight gain, a secondary phenotype after gonadectomy, showed a significant but separate quantitative trait locus on chromosome 7. Altogether, postgonadectomy adrenocortical tumorigenesis in DBA/2J mice is a dominant trait that is not a direct consequence of adrenal LHR expression but is driven by a complex genetic architecture. Analysis of candidate genes in the tumorigenesis linkage region showed that Sfrp1 (secreted frizzled-related protein 1), a tumor suppressor gene, is differentially expressed in the neoplastic areas. These findings may have relevance to the human pathogenesis of macronodular adrenal hyperplasia and adrenocortical tumors in postmenopausal women and why some of them develop obesity.
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Affiliation(s)
- Sophie Bernichtein
- Department of Reproductive Biology, Physiological Genomics and Medicine Group, Medical Research Council, Clinical Sciences Center, Faculty of Medicine, Imperial College London, London, UK
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Abstract
Originally, comparative genomics was geared toward defining the synteny of genes between species. As the human genome project accelerated, there was an increase in the number of tools and means to make comparisons culminating in having the genomic sequence for a large number of organisms spanning the evolutionary tree. With this level of resolution and a long history of comparative biology and comparative genetics, it is now possible to use comparative genomics to build or select better animal models and to facilitate gene discovery. Comparative genomics takes advantage of the functional genetic information from other organisms, (vertebrates and invertebrates), to apply it to the study of human physiology and disease. It allows for the identification of genes and regulatory regions, and for acquiring knowledge about gene function. In this chapter, the current state of comparative genomics and the available tools are discussed in the context of developing animal model systems that reflect the clinical picture.
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Affiliation(s)
- Carol Moreno
- Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Yamanouchi J, Rainbow D, Serra P, Howlett S, Hunter K, Garner VES, Gonzalez-Munoz A, Clark J, Veijola R, Cubbon R, Chen SL, Rosa R, Cumiskey AM, Serreze DV, Gregory S, Rogers J, Lyons PA, Healy B, Smink LJ, Todd JA, Peterson LB, Wicker LS, Santamaria P. Interleukin-2 gene variation impairs regulatory T cell function and causes autoimmunity. Nat Genet 2007; 39:329-37. [PMID: 17277778 PMCID: PMC2886969 DOI: 10.1038/ng1958] [Citation(s) in RCA: 304] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Accepted: 12/20/2006] [Indexed: 12/12/2022]
Abstract
Autoimmune diseases are thought to result from imbalances in normal immune physiology and regulation. Here, we show that autoimmune disease susceptibility and resistance alleles on mouse chromosome 3 (Idd3) correlate with differential expression of the key immunoregulatory cytokine interleukin-2 (IL-2). In order to test directly that an approximately twofold reduction in IL-2 underpins the Idd3-linked destabilization of immune homeostasis, we show that engineered haplodeficiency of Il2 gene expression not only reduces T cell IL-2 production by twofold but also mimics the autoimmune dysregulatory effects of the naturally occurring susceptibility alleles of Il2. Reduced IL-2 production achieved by either genetic mechanism correlates with reduced function of CD4(+) CD25(+) regulatory T cells, which are critical for maintaining immune homeostasis.
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Affiliation(s)
- Jun Yamanouchi
- Julia McFarlane Diabetes Research Centre (JMDRC) and Department of Microbiology and Infectious Diseases, Institute of Inflammation, Infection and Immunity, Faculty of Medicine, The University of Calgary, Calgary, Alberta T2N 4N1, Canada
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Abstract
In recent years in silico analysis of common laboratory mice has been introduced and subsequently applied, in slightly different ways, as a methodology for gene mapping. Previously we have demonstrated some limitation of the methodology due to sporadic genetic correlations across the genome. Here, we revisit the three main aspects that affect in silico analysis. First, we report on the use of marker maps: we compared our existing 20,000 SNP map to the newly released 140,000 SNP map. Second, we investigated the effect of varying strain numbers on power to map QTL. Third, we introduced a novel statistical approach: a cladistic analysis, which is well suited for mouse genetics and has increased flexibility over existing in silico approaches. We have found that in our examples of complex traits, in silico analysis by itself does fail to uniquely identify quantitative trait gene (QTG)-containing regions. However, when combined with additional information, it may significantly help to prioritize candidate genes. We therefore recommend using an integrated work flow that uses other genomic information such as linkage regions, regions of shared ancestry, and gene expression information to obtain a list of candidate genes from the genome.
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