scholarly journals MHC-Linked Olfactory Receptor Loci Exhibit Polymorphism and Contribute to Extended HLA/OR-Haplotypes

2000 ◽  
Vol 10 (12) ◽  
pp. 1968-1978 ◽  
Author(s):  
Anke Ehlers ◽  
Stephan Beck ◽  
Simon A. Forbes ◽  
John Trowsdale ◽  
Armin Volz ◽  
...  

Clusters of olfactory receptor (OR) genes are found on most human chromosomes. They are one of the largest mammalian multigene families. Here, we report a systematic study of polymorphism of OR genes belonging to the largest fully sequenced OR cluster. The cluster contains 36 OR genes, of which two belong to the vomeronasal 1 (V1-OR) family. The cluster is divided into a major and a minor region at the telomeric end of the HLA complex on chromosome 6. These OR genes could be involved in MHC-related mate preferences. The polymorphism screen was carried out with 13 genes from the HLA-linked OR cluster and three genes from chromosomes 7, 17, and 19 as controls. Ten human cell lines, representing 18 different chromosome 6s, were analyzed. They were from various ethnic origins and exhibited different HLA haplotypes. All OR genes tested, including those not linked to the HLA complex, were polymorphic. These polymorphisms were dispersed along the coding region and resulted in up to seven alleles for a given OR gene. Three polymorphisms resulted either in stop codons (genes hs6M1-4P,hs6M1-17) or in a 16–bp deletion (gene hs6M1-19P), possibly leading to lack of ligand recognition by the respective receptors in the cell line donors. In total, 13 HLA-linked OR haplotypes could be defined. Therefore, allelic variation appears to be a general feature of human OR genes.[The sequence data reported in this paper have been submitted to EMBL under accession nos. AC006137, AC004178, AJ132194, AL022727, AL031983,AL035402, AL035542, Z98744, CAB55431, AL050339, AL035402, AL096770,AL133267, AL121944, Z98745, AL021808, and AL021807.]

2019 ◽  
Author(s):  
If Barnes ◽  
Ximena Ibarra-Soria ◽  
Stephen Fitzgerald ◽  
Jose Gonzalez ◽  
Claire Davidson ◽  
...  

Abstract Olfactory receptor (OR) genes are the largest multi-gene family in the mammalian genome, with over 850 in human and nearly 1500 genes in mouse. The expansion of the OR gene repertoire has occurred through numerous duplication events followed by diversification, resulting in a large number of highly similar paralogous genes. These characteristics have made the annotation of the complete OR gene repertoire a complex task. Most OR genes have been predicted in silico and are typically annotated as intronless coding sequences. Here we have developed an expert curation pipeline to analyse and annotate every OR gene in the human and mouse reference genomes. By combining evidence from structural features, evolutionary conservation and experimental data, we have unified the annotation of these gene families, and have systematically determined the protein-coding potential of each locus. We have defined the non-coding regions of many OR genes, enabling us to generate full-length transcript models. We found that 13 human and 41 mouse OR loci have coding sequences that are split across two exons. These split OR genes are conserved across mammals, and are expressed at the same level as protein-coding OR genes with an intronless coding region. Our findings challenge the long-standing and widespread notion that the coding region of a vertebrate OR gene is contained within a single exon.


2019 ◽  
Author(s):  
If H. A. Barnes ◽  
Ximena Ibarra-Soria ◽  
Stephen Fitzgerald ◽  
Jose M. Gonzalez ◽  
Claire Davidson ◽  
...  

ABSTRACTOlfactory receptor (OR) genes are the largest multi-gene family in the mammalian genome, with over 850 in human and nearly 1500 genes in mouse. The expansion of the OR gene repertoire has occurred through numerous duplication events followed by diversification, resulting in a large number of highly similar paralogous genes. These characteristics have made the annotation of the complete OR gene repertoire a complex task. Most OR genes have been predicted in silico and are typically annotated as intronless coding sequences. Here we have developed an expert curation pipeline to analyse and annotate every OR gene in the human and mouse reference genomes. By combining evidence from structural features, evolutionary conservation and experimental data, we have unified the annotation of these gene families, and have systematically determined the protein-coding potential of each locus. We have defined the non-coding regions of many OR genes, enabling us to generate full-length transcript models. We found that 13 human and 41 mouse OR loci have coding sequences that are split across two exons. These split OR genes are conserved across mammals, and are expressed at the same level as protein-coding OR genes with an intronless coding region. Our findings challenge the long-standing and widespread notion that the coding region of a vertebrate OR gene is contained within a single exon.


2020 ◽  
Author(s):  
If Barnes ◽  
Ximena Ibarra-Soria ◽  
Stephen Fitzgerald ◽  
Jose Gonzalez ◽  
Claire Davidson ◽  
...  

Abstract Background: Olfactory receptor (OR) genes are the largest multi-gene family in the mammalian genome, with 874 in human and 1483 loci in mouse (including pseudogenes). The expansion of the OR gene repertoire has occurred through numerous duplication events followed by diversification, resulting in a large number of highly similar paralogous genes. These characteristics have made the annotation of the complete OR gene repertoire a complex task. Most OR genes have been predicted in silico and are typically annotated as intronless coding sequences. Results: Here we have developed an expert curation pipeline to analyse and annotate every OR gene in the human and mouse reference genomes. By combining evidence from structural features, evolutionary conservation and experimental data, we have unified the annotation of these gene families, and have systematically determined the protein-coding potential of each locus. We have defined the non-coding regions of many OR genes, enabling us to generate full-length transcript models. We found that 13 human and 41 mouse OR loci have coding sequences that are split across two exons. These split OR genes are conserved across mammals, and are expressed at the same level as protein-coding OR genes with an intronless coding region. Our findings challenge the long-standing and widespread notion that the coding region of a vertebrate OR gene is contained within a single exon.Conclusions: This work provides the most comprehensive curation effort of the human and mouse OR gene repertoires to date. The complete annotation has been integrated into the GENCODE reference gene set, for immediate availability to the research community.


2020 ◽  
Author(s):  
If Habib Ahmed Barnes ◽  
Ximena Ibarra-Soria ◽  
Stephen Fitzgerald ◽  
Jose Manuel Gonzalez ◽  
Claire Davidson ◽  
...  

Abstract Background: Olfactory receptor (OR) genes are the largest multi-gene family in the mammalian genome, with 874 in human and 1483 loci in mouse (including pseudogenes). The expansion of the OR gene repertoire has occurred through numerous duplication events followed by diversification, resulting in a large number of highly similar paralogous genes. These characteristics have made the annotation of the complete OR gene repertoire a complex task. Most OR genes have been predicted in silico and are typically annotated as intronless coding sequences. Results: Here we have developed an expert curation pipeline to analyse and annotate every OR gene in the human and mouse reference genomes. By combining evidence from structural features, evolutionary conservation and experimental data, we have unified the annotation of these gene families, and have systematically determined the protein-coding potential of each locus. We have defined the non-coding regions of many OR genes, enabling us to generate full-length transcript models. We found that 13 human and 41 mouse OR loci have coding sequences that are split across two exons. These split OR genes are conserved across mammals, and are expressed at the same level as protein-coding OR genes with an intronless coding region. Our findings challenge the long-standing and widespread notion that the coding region of a vertebrate OR gene is contained within a single exon.Conclusions: This work provides the most comprehensive curation effort of the human and mouse OR gene repertoires to date. The complete annotation has been integrated into the GENCODE reference gene set, for immediate availability to the research community.


2020 ◽  
Author(s):  
If Habib Ahmed Barnes ◽  
Ximena Ibarra-Soria ◽  
Stephen Fitzgerald ◽  
Jose Manuel Gonzalez ◽  
Claire Davidson ◽  
...  

Abstract Background Olfactory receptor (OR) genes are the largest multi-gene family in the mammalian genome, with 874 in human and 1483 loci in mouse (including pseudogenes). The expansion of the OR gene repertoire has occurred through numerous duplication events followed by diversification, resulting in a large number of highly similar paralogous genes. These characteristics have made the annotation of the complete OR gene repertoire a complex task. Most OR genes have been predicted in silico and are typically annotated as intronless coding sequences. Results Here we have developed an expert curation pipeline to analyse and annotate every OR gene in the human and mouse reference genomes. By combining evidence from structural features, evolutionary conservation and experimental data, we have unified the annotation of these gene families, and have systematically determined the protein-coding potential of each locus. We have defined the non-coding regions of many OR genes, enabling us to generate full-length transcript models. We found that 13 human and 41 mouse OR loci have coding sequences that are split across two exons. These split OR genes are conserved across mammals, and are expressed at the same level as protein-coding OR genes with an intronless coding region. Our findings challenge the long-standing and widespread notion that the coding region of a vertebrate OR gene is contained within a single exon. Conclusions This work provides the most comprehensive curation effort of the human and mouse OR gene repertoires to date. The complete annotation has been integrated into the GENCODE reference gene set, for immediate availability to the research community.


PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245324
Author(s):  
Snehal Dilip Karpe ◽  
Vikas Tiwari ◽  
Sowdhamini Ramanathan

Insect Olfactory Receptors (ORs) are diverse family of membrane protein receptors responsible for most of the insect olfactory perception and communication, and hence they are of utmost importance for developing repellents or pesticides. Accurate gene prediction of insect ORs from newly sequenced genomes is an important but challenging task. We have developed a dedicated webserver, ‘insectOR’, to predict and validate insect OR genes using multiple gene prediction algorithms, accompanied by relevant validations. It is possible to employ this server nearly automatically and perform rapid prediction of the OR gene loci from thousands of OR-protein-to-genome alignments, resolve gene boundaries for tandem OR genes and refine them further to provide more complete OR gene models. InsectOR outperformed the popular genome annotation pipelines (MAKER and NCBI eukaryotic genome annotation) in terms of overall sensitivity at base, exon and locus level, when tested on two distantly related insect genomes. It displayed more than 95% nucleotide level precision in both tests. Finally, given the same input data and parameters, InsectOR missed less than 2% gene loci, in contrast to 55% loci missed by MAKER for Drosophila melanogaster. The webserver is freely available on the web at http://caps.ncbs.res.in/insectOR/ and the basic package can be downloaded from https://github.com/sdk15/insectOR for local use. This tool will allow biologists to perform quick preliminary identification of insect olfactory receptor genes from newly sequenced genomes and also assist in their further detailed annotation. Its usage can also be extended to other divergent gene families.


1985 ◽  
Vol 5 (9) ◽  
pp. 2197-2203
Author(s):  
M S Lakshmikumaran ◽  
E D'Ambrosio ◽  
L A Laimins ◽  
D T Lin ◽  
A V Furano

The insulin 1, but not the insulin 2, locus is polymorphic (i.e., exhibits allelic variation) in rats. Restriction enzyme analysis and hybridization studies showed that the polymorphic region is 2.2 kilobases upstream of the insulin 1 coding region and is due to the presence or absence of an approximately 2.7-kilobase repeated DNA element. DNA sequence determination showed that this DNA element is a member of a long interspersed repeated DNA family (LINE) that is highly repeated (greater than 50,000 copies) and highly transcribed in the rat. Although the presence or absence of LINE sequences at the insulin 1 locus occurs in both the homozygous and heterozygous states, LINE-containing insulin 1 alleles are more prevalent in the rat population than are alleles without LINEs. Restriction enzyme analysis of the LINE-containing alleles indicated that at least two versions of the LINE sequence may be present at the insulin 1 locus in different rats. Either repeated transposition of LINE sequences or gene conversion between the resident insulin 1 LINE and other sequences in the genome are possible explanations for this.


2019 ◽  
Vol 286 (1904) ◽  
pp. 20190909 ◽  
Author(s):  
Graham M. Hughes ◽  
John A. Finarelli

The olfactory bulb (OB) ratio is the size of the OB relative to the cerebral hemisphere, and is used to estimate the proportion of the forebrain devoted to smell. In birds, OB ratio correlates with the number of olfactory receptor (OR) genes and therefore has been used as a proxy for olfactory acuity. By coupling OB ratios with known OR gene repertoires in birds, we infer minimum repertoire sizes for extinct taxa, including non-avian dinosaurs, using phylogenetic modelling, ancestral state reconstruction and comparative genomics. We highlight a shift in the scaling of OB ratio to body size along the lineage leading to modern birds, demonstrating variable OR repertoires present in different dinosaur and crown-bird lineages, with varying factors potentially influencing sensory evolution in theropods. We investigate the ancestral sensory space available to extinct taxa, highlighting potential adaptations to ecological niches. Through combining morphological and genomic data, we show that, while genetic information for extinct taxa is forever lost, it is potentially feasible to investigate evolutionary trajectories in extinct genomes.


1985 ◽  
Vol 5 (9) ◽  
pp. 2197-2203 ◽  
Author(s):  
M S Lakshmikumaran ◽  
E D'Ambrosio ◽  
L A Laimins ◽  
D T Lin ◽  
A V Furano

The insulin 1, but not the insulin 2, locus is polymorphic (i.e., exhibits allelic variation) in rats. Restriction enzyme analysis and hybridization studies showed that the polymorphic region is 2.2 kilobases upstream of the insulin 1 coding region and is due to the presence or absence of an approximately 2.7-kilobase repeated DNA element. DNA sequence determination showed that this DNA element is a member of a long interspersed repeated DNA family (LINE) that is highly repeated (greater than 50,000 copies) and highly transcribed in the rat. Although the presence or absence of LINE sequences at the insulin 1 locus occurs in both the homozygous and heterozygous states, LINE-containing insulin 1 alleles are more prevalent in the rat population than are alleles without LINEs. Restriction enzyme analysis of the LINE-containing alleles indicated that at least two versions of the LINE sequence may be present at the insulin 1 locus in different rats. Either repeated transposition of LINE sequences or gene conversion between the resident insulin 1 LINE and other sequences in the genome are possible explanations for this.


2001 ◽  
Vol 11 (4) ◽  
pp. 519-530 ◽  
Author(s):  
Ruth M. Younger ◽  
Claire Amadou ◽  
Graeme Bethel ◽  
Anke Ehlers ◽  
Kirsten Fischer Lindahl ◽  
...  

Olfactory receptor (OR) loci frequently cluster and are present on most human chromosomes. They are members of the seven transmembrane receptor (7-TM) superfamily and, as such, are part of one of the largest mammalian multigene families, with an estimated copy number of up to 1000 ORs per haploid genome. As their name implies, ORs are known to be involved in the perception of odors and possibly also in other, nonolfaction-related, functions. Here, we report the characterization of ORs that are part of the MHC-linked OR clusters in human and mouse (partial sequence only). These clusters are of particular interest because of their possible involvement in olfaction-driven mate selection. In total, we describe 50 novel OR loci (36 human, 14 murine), making the human MHC-linked cluster the largest sequenced OR cluster in any organism so far. Comparative and phylogenetic analyses confirm the cluster to be MHC-linked but divergent in both species and allow the identification of at least one ortholog that will be useful for future regulatory and functional studies. Quantitative feature analysis shows clear evidence of duplications of blocks of OR genes and reveals the entire cluster to have a genomic environment that is very different from its neighboring regions. Based on in silico transcript analysis, we also present evidence of extensive long-distance splicing in the 5′-untranslated regions and, for the first time, of alternative splicing within the single coding exon of ORs. Taken together with our previous finding that ORs are also polymorphic, the presented data indicate that the expression, function, and evolution of these interesting genes might be more complex than previously thought.[The sequence data described in this paper have been submitted to the EMBL nucleotide data library under accession nos.Z84475, Z98744, Z98745, AL021807, AL021808, AL022723, AL022727,AL031893, AL035402, AL035542, AL050328, AL050339, AL078630, AL096770,AL121944, AL133160, and AL133267.]


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