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Results for “Expression quantitative trait locus analysis”

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PubMed2004

Refinement of the 6p21.3 quantitative trait locus influencing dyslexia: linkage and association analyses.

Reading disability (RD), or dyslexia, is the most common learning disability with a prevalence rate of ~5%-10% in school-age children. RD is highly heritable with evidence of a neurobiological origin. Linkage studies have identified several quantitative trait loci (QTLs) for RD. The QTL on chromosome 6p21.3 has been independently replicated by several groups and spans a 16.4-Mb (13.8 cM) interval from D6S109 to D6S291. In this study, we performed sib-pair linkage analyses with Haseman-Elston and DeFries-Fulker methods to define more accurately the QTL interval. Linkage was assessed by using five quantitative phenotypes, including a composite measure of reading performance and four component phenotypes. When probands were selected for severe scores, single- and multi-point analyses showed significant linkage with all five phenotypes, converging over an interval of ~3.24 Mb spanning D6S1597 to D6S1571. Maximal linkage converged at marker D6S1554 across phenotypes. Out of 12 genes in the linkage interval, ten clustered within ~680 kb and were selected for association analysis based on central nervous system expression and putative function. Marker-trait associations were assessed by using QTDT (a general test of association for quantitative traits) and the family-based association test (FBAT), and haplotype analysis was performed by using FBAT and the GeneHunter Transmission/Disequilibrium Test TDT. Marker associations were detected in five of the ten genes, results that were corroborated by our haplotype TDT analysis. The results of the association study have thereby allowed us to significantly reduce the number of possible candidate genes and to prioritize genes for further mutation screening.

Adolescent↗
PubMed1999

Temporal expression of an H2-linked locus in host response to mouse malaria.

The action of host genes in response to malarial infection is complex. Two mouse loci, Char1, and Char2, have previously been shown to control peak parasitemia and host survival. Recent analysis of host response to mouse malaria has demonstrated that the action of several loci is time dependent. Char1 and Char2 act prior to peak parasitemia. Analysis of additional crosses revealed significant linkage to Chromosome 17 on the day following peak parasitemia. This H2-linked locus acts late in infection and is therefore crucial in clearing parasites from the circulation. The cloning of this gene will lead to a greater understanding of the host-parasite interaction, and the kinetics of host gene expression during an immune response.

Animals↗
PubMed1998

Sex-specific modifiers of tail development in mice heterozygous for the brachyury (T) mutation.

The brachyury, or T, locus encodes a transcription factor that plays a crucial role in the early development of all animals. In the mouse, animals heterozygous for a null mutation at this locus are born with a characteristic short tail. Expressivity of the short tail phenotype is greatly affected by genetic background. As a genetic entry into the identification of genes that interact with the Brachyury locus, we have performed a QTL analysis for modifiers of this phenotype. Surprisingly, we discovered that the major modifiers uncovered all act in a sex-limited manner. We have identified two QTLs--Brm1 on Chr 9 and Brm2 on Chr 15--that act only in female offspring(N2) from female T/+ parents(F1) and are responsible together for most, or all, of the genetic variance in phenotypic expression observed between C57BL/10 and C3H/HeJ animals.

Animals↗
PubMed2005

Transformation of maize with the p1 transcription factor directs production of silk maysin, a corn earworm resistance factor, in concordance with a hierarchy of floral organ pigmentation.

The maize p1 gene encodes an R2R3-MYB transcription factor that controls the biosynthesis of red flavonoid pigments in floral tissues of the maize plant. Genetic and quantitative trait locus analyses have also associated the p1 gene with the synthesis of maysin, a flavone glycoside from maize silks that confers natural resistance to corn earworm. Here, we show directly that the p1 gene induces maysin accumulation in silk tissues. Transformation of maize plants that had low or no silk maysin with p1 transgenes elevated silk maysin concentrations to levels sufficient for corn earworm abiosis. The p1 transgenes also conferred red pigment to pericarp, cob, husk and tassel tissues, as expected; however, different subsets of these tissues were pigmented within individual transgenic plants. Statistical analysis shows that the pigmentation patterns observed amongst the p1 transgenic plants conform to a hierarchy that is similar to the temporal ordering of floral organ initiation. We propose that the observed hierarchy of pigmentation patterns is conferred by variation due to epigenetic control of the p1 transgenes. The production of plants with improved traits through genetic engineering can depend in large part on the achievement of tight organ-specific expression of the introduced transgenes. Our results demonstrate that the production of transgenic plants using a promoter with well-defined tissue specificity, such as the p1 promoter, can result in unexpected variation in tissue specificity amongst the resulting transgenic plants.

Journal Article↗
PubMed1999

Altered structure, regulation, and function of the gene encoding the atrial natriuretic peptide in the stroke-prone spontaneously hypertensive rat.

Through the genotype/phenotype cosegregation analysis of an F(2) intercross, from the crossbreeding of stroke-prone spontaneously hypertensive rats (SHRSP) and stroke-resistant spontaneously hypertensive rats (SHR), we previously identified a quantitative trait locus for stroke on rat chromosome 5 (STR2) that colocalized with the genes encoding atrial and brain natriuretic peptides (ANP and BNP) and conferred a stroke-delaying effect. To further characterize ANP and BNP as candidates for stroke, we performed additional studies. Comparative sequence analysis revealed point mutations in both the coding and regulatory regions of ANP, whereas no interstrain differences were found for BNP. In in vitro studies in COS-7 and AtT-20 cells that were performed to test the relevance of a G-->A substitution at position 1125, a Gly-->Ser transposition in the SHRSP pro-ANP peptide resulted in different posttranslational processing of the SHRSP ANP gene product that was also associated with higher cGMP production (P<0.05). Furthermore, an analysis of a 5' end mutation affecting a PEA2 regulatory binding site in the 5' untranslated regulatory sequence of SHRSP ANP demonstrated a significantly lower ANP promoter activation in endothelial cells (P<0.05 versus the SHR ANP). In addition, the expression of ANP was significantly reduced in the brain, but not in the atria, of SHRSP compared with SHR (P<0.0001). No differences were detected with regard to BNP expression. The present results reveal substantial differences in ANP, but not BNP, structure and product among SHR and SHRSP, which supports a role of ANP in the pathogenesis of stroke in the SHRSP animal model.

Animals↗
PubMed1997

Genetic analysis of the components of winterhardiness in barley (Hordeum vulgar L.).

Winterhardiness in cereals is the consequence of a number of complex and interacting components: cold tolerance, vernalization requirement and photoperiod sensitivity. An understanding of the genetic basis of these component traits should allow for more effective selection. Genome map-based analyses hold considerable promise for dissecting complex phenotypes. A 74-point linkage map was developed from one hundred double haploid lines derived from a winter x spring barley cross and used as the basis for quantitative trait locus (QTL) analyses to determine the chromosome location of genes controlling components of winterhardiness. Despite the greater genome coverage provided by the current map, a previously-reported interval on chromosome 7 remains the only region where significant QTL effects for winter survival were detected in this population. QTLs for heading date under 24 h light map to the same region. A QTL for heading date under this photoperiod regime also maps to chromosome 2. A distinct set of QTLs mapping to chromosomes 1, 2, 3 and 5 determined heading date under 8 h light. Patterns of differential QTL expression underscore the complexity of Winterhardiness.

Acclimatization↗
PubMedDate not supplied

Additional evidence that the K-ras protooncogene is a candidate for the major mouse pulmonary adenoma susceptibility (Pas-1) gene.

A locus for mouse pulmonary adenoma susceptibility, Pas-1, has been mapped on distal chromosome 6, where the K-ras gene is located. Allele-specific activation and expression of the K-ras allele from the susceptible parent has been observed in lung tumors from F1 hybrid mice. We report here genetic mapping of lung tumor susceptibility genes in urethane-treated A x B and B x A recombinant inbred (RI) mice using microsatellite markers to seek further evidence for the K-ras gene as candidate for Pas-1. The K-ras genotype differs between the A/J and C57BL/6J progenitors of the RI strains, and distal chromosome 6 contained a major lung tumor susceptibility determinant in the RI mice. Additional evidence that Pas-1 is K-ras involved linkage analysis of (A/JOLaHsd x BALB/ cOLaHsd) F2 intercross mice whose parents shared the same K-ras genotype. In contrast to the results with the A x B and B x A RI strains, no distal chromosome 6 site was significantly associated with tumor development in these F2 mice. In addition to this major locus, linkage analysis of the RI mice revealed additional quantitative trait loci for susceptibility on chromosomes 10, 17, and 19. These loci may serve as modifiers of Pas-1. The relationship between the K-ras genotype and the frequency of K-ras mutations in urethane-induced lung tumors from the RI mice was also explored. All 18 tumor DNAs from RI mice with high susceptibility contained an AT-->TA transversion at the second base of K-ras codon 61. This was also true for DNAs from 27 of 27 (100%) tumors in mice with high intermediate susceptibility. In RI strains with a low intermediate susceptibility, the DNA from 39 of 47 (83%) tumors contained an AT-->TA transversion at codon 61, and only 13 of 21 (62%) tumors had this mutation in the most resistant group. This reflects a positive correlation between the frequency of K-ras mutations in lung tumors of A x B or B x A RI strains and their susceptibility to lung carcinogenesis. Since K-ras appears to be Pas-1, these results suggest that some RI mice that have the resistant K-ras or Pas-1 allele undergo tumor development by a K-ras-independent route.

Adenoma↗
PubMed2005

Pleiotropic effects of the duplicate maize FLORICAULA/LEAFY genes zfl1 and zfl2 on traits under selection during maize domestication.

Phenotypic variation on which selection can act during evolution may be caused by variation in activity level of developmental regulatory genes. In many cases, however, such genes affect multiple traits. This situation can lead to co-evolution of traits, or evolutionary constraint if some pleiotropic effects are detrimental. Here, we present an analysis of quantitative traits associated with gene copy number of two important maize regulatory genes, the duplicate FLORICAULA/LEAFY orthologs zfl1 and zfl2. We found statistically significant associations between several quantitative traits and copy number of both zfl genes in several maize genetic backgrounds. Despite overlap in traits associated with these duplicate genes, zfl1 showed stronger associations with flowering time, while zfl2 associated more strongly with branching and inflorescence structure traits, suggesting some divergence of function. Since zfl2 associates with quantitative variation for ear rank and also maps near a quantitative trait locus (QTL) on chromosome 2 controlling ear rank differences between maize and teosinte, we tested whether zfl2 might have been involved in the evolution of this trait using a QTL complementation test. The results suggest that zfl2 activity is important for the QTL effect, supporting zfl2 as a candidate gene for a role in morphological evolution of maize.

Biological Evolution↗
PubMed2004

Expression of PEG11 and PEG11AS transcripts in normal and callipyge sheep.

BACKGROUND: The callipyge mutation is located within an imprinted gene cluster on ovine chromosome 18. The callipyge trait exhibits polar overdominant inheritance due to the fact that only heterozygotes inheriting a mutant paternal allele (paternal heterozygotes) have a phenotype of muscle hypertrophy, reduced fat and a more compact skeleton. The mutation is a single A to G transition in an intergenic region that results in the increased expression of several genes within the imprinted cluster without changing their parent-of-origin allele-specific expression. RESULTS: There was a significant effect of genotype (p < 0.0001) on the transcript abundance of DLK1, PEG11, and MEG8 in the muscles of lambs with the callipyge allele. DLK1 and PEG11 transcript levels were elevated in the hypertrophied muscles of paternal heterozygous animals relative to animals of the other three genotypes. The PEG11 locus produces a single 6.5 kb transcript and two smaller antisense strand transcripts, referred to as PEG11AS, in skeletal muscle. PEG11AS transcripts were detectable over a 5.5 kb region beginning 1.2 kb upstream of the PEG11 start codon and spanning the entire open reading frame. Analysis of PEG11 expression by quantitative PCR shows a 200-fold induction in the hypertrophied muscles of paternal heterozygous animals and a 13-fold induction in homozygous callipyge animals. PEG11 transcripts were 14-fold more abundant than PEG11AS transcripts in the gluteus medius of paternal heterozygous animals. PEG11AS transcripts were expressed at higher levels than PEG11 transcripts in the gluteus medius of animals of the other three genotypes. CONCLUSIONS: The effect of the callipyge mutation has been to alter the expression of DLK1, GTL2, PEG11 and MEG8 in the hypertrophied skeletal muscles. Transcript abundance of DLK1 and PEG11 was highest in paternal heterozygous animals and exhibited polar overdominant gene expression patterns; therefore, both genes are candidates for causing skeletal muscle hypertrophy. There was unique relationship of PEG11 and PEG11AS transcript abundance in the paternal heterozygous animals that suggests a RNA interference mechanism may have a role in PEG11 gene regulation and polar overdominance in callipyge sheep.

Animals↗
PubMed2004

Genetic analysis of inherited hydrocephalus in a rat model.

Congenital hydrocephalus is a serious neurological disorder with a diverse etiology. Although there is strong evidence for genetic causes, few genes have been identified in humans. The rodent model, the H-Tx rat, has hydrocephalus with an onset in late gestation and a complex mode of inheritance. Ventricular dilatation is associated with abnormalities in the cerebral aqueduct and subcommissural organ. Quantitative trait locus (QTL) mapping was performed on DNA from the progeny of a backcross with the non-hydrocephalic Fischer F344 strain, using DNA microsatellite markers. The hydrocephalus trait was quantified by measuring the severity of the ventricular dilatation. Four chromosomes, each with a locus for hydrocephalus (Chrs 9, 10, 11, and 17), were mapped using additional markers and DNA from four subsets of backcross progeny with allelic recombination at or near each locus. The genetic positions for the markers and the loci were located using the Ensemble Rat Genome Browser. For each chromosome studied, the interval containing the locus was examined for known rat genes and for human genes identified from human-rat homology. Genes expressed in brain and with a function associated with known causes of hydrocephalus were identified as possible candidate genes. Future studies to characterize the causative genes in this animal model will improve the understanding of genetic causes in humans.

Animals↗
PubMed1998

Analysis of the mesotelencephalic dopamine system by quantitative-trait locus introgression.

One of the significant factors that affect brain dopamine function is the activity of tyrosine hydroxylase (TH), the first and rate-limiting enzyme in catecholamine biosynthesis. For the analysis of the genetically determined role of dopamine function and TH in behavior and in the regulatory mechanisms of the mesotelencephalic dopamine system we devised a novel genetic strategy (Vadasz; Mouse Genome 88:16-18; 1990). We hypothesized that phenotypic introgression and recombinant fixation could ensure the transfer of Quantitative Trait Loci (QTL) from one strain onto the genetic background of another strain, and new, genetically very similar quasi-congenic strains could be created that would carry individual QTLs, or QTLs in various combinations. Here we summarize the construction of the first set of QTL Introgression strains, and present evidence that QTLs that are responsible for the continuous variation of mesencephalic tyrosine hydroxylase activity (TH/MES), have been transferred onto the C57BL/6By (B6) strain background from BALB/cJ (C) and CXBI (I) donor strains with high and low TH/MES, respectively. The QTL transfer was carried out in two directions by repeated backcross-intercross cycles with concomitant selection for the extreme high and low expressions of TH/MES in replicates, resulting in four QTL Introgression lines. Analysis of regional brain TH activities in the course of the QTL introgression indicated that (a) TH activity in B6.I lines showed quite limited heritability, (b) TH/MES was not highly correlated with striatal TH, and (c) the control of hypothalamic and olfactory tubercle TH activities was largely independent from that of TH/MES. Examination of the open-field (OF) behavior data demonstrated that TH activity did not correlate significantly with OF behavior. After 5 backcross-intercross cycles, TH/MES in each replicate line was still significantly different from that of the B6 background strain. A genomewide scanning of microsatellite markers in the QTL introgression lines demonstrated that about 96% of the markers were of background (B6) type. These results indicate the successful transfer of TH/MES QTLs. After the QTL transfer phase of the experiment altogether more than 100 new RQI strains were initiated in the QTL Introgression lines by strict brother x sister mating. After fixing the introgressed QTLs, ten of the inbred RQI strains were tested for TH/MES. The results showed that in one of the new RQI strains TH/MES was restored to a level that is characteristic to the C donor strain, while TH/MES values in some other strains were between those of the background and donor strains, confirming our hypothesis that phenotypic introgression and recombinant fixation can ensure a virtually complete transfer of QTLs. We conclude from this study that complex, continuously distributed neural traits can successfully be subjected to QTL introgression, and the results raise the possibility that the RQI method can be efficiently applied for gene mapping of complex neural and behavioral traits even if their phenotypic expression is sensitive to confounding developmental and environmental variations, genetic interactions, and genotype-environment interactions.

Animals↗
PubMed2026

Identification and fine mapping of a locus controlling multi-main-stem trait in Brassica napus.

BACKGROUND: The main stem is a crucial component determining individual plant yield in rapeseed (Brassica napus). However, the genetic and developmental basis underlying the multi-main-stem trait remains largely unclear. RESULTS: In this study, we identified a multi-main-stem mutant, mms1, which exhibited a significantly increased silique number per plant and abnormal shoot apical meristem (SAM) development. Genetic analysis demonstrated that the multi-main-stem trait was controlled by a recessive gene. Using bulked segregant analysis combined with a Brassica napus 50&#xa0;K SNP array and map-based cloning, the locus was mapped to a 340-kb interval on chromosome A09 of the ZS11 reference genome and was designated BnaA09.MMS1. Candidate gene analysis revealed that BnaA09G0254500ZS, which harbors sequence variations in both the promoter and coding regions and shows significantly increased expression in the mutant, was the most likely candidate gene. In addition, phytohormone analysis revealed reduced auxin accumulation in mutant SAMs, together with transcriptomic changes in genes associated with the CLAVATA3 (CLV3)-WUSCHEL (WUS) feedback loop. CONCLUSIONS: These findings provide an important foundation for elucidating the genetic basis of the multi-main-stem trait and offer a valuable genetic resource for rapeseed improvement.

Brassica napus↗
PubMed2004

Mapping of QTLs prolonging the latent period of Puccinia triticina infection in wheat.

Slow rusting is considered a crucial component of durable resistance to wheat leaf rust caused by Puccinia triticina and is often expressed in the form of a prolonged latent period. Selection for a longer latent period is considered an effective approach to developing wheat cultivars with improved durable resistance to leaf rust. A recombinant inbred line (RIL) population derived from CI 13227 (long latent period) x Suwon 92 (short latent period) was phenotyped for latent period in two greenhouse experiments in separate years, and amplified fragment length polymorphism (AFLP) and simple sequence repeat (SSR) markers were analyzed in the same population. Among the RILs, the frequency distribution for latent period was continuous, and latent period was highly correlated between years (r=0.94, P<0.0001). A quantitative trait locus (QTL) prolonging the latent period of P. triticina, designated as QLrlp.osu-2DS, explained 42.8% and 54.5% of the phenotypic and genetic variance in the two experiments, respectively. QLrlp.osu-2DS was mapped on the distal region of chromosome 2DS. Two other QTLs for latent period, QLrlp.osu-2B and QLrlp.osu-7BL, were localized on chromosome 2B and the long arm of chromosome 7B, respectively. Multiple regression analysis showed that these three QTLs collectively explained 58.0% and 73.8% of the phenotypic and genetic variance over two experiments, respectively. Fourteen RILs that carried all three alleles for long latent period at three AFLP loci flanking QLrlp.osu-2DS, QLrlp.osu-2B, and QLrlp.osu-7BL had a mean latent period of 12.5 days, whereas 13 RILs without any long-latent-period alleles at the corresponding loci had a mean latent period of 7.4 days. Three SSR markers closely linked to these QTLs have potential to be applied in marker-assisted selection for prolonged latent period in wheat.

Basidiomycota↗
PubMed2006

Identifying genes associated with a quantitative trait or quantitative trait locus via selective transcriptional profiling.

Genetical genomics is an approach that blends the mapping of quantitative trait loci (QTL) with microarray analysis. The approach can be used to identify associations between the allelic state of a genomic region and a gene's transcript abundance. However, the large number of microarrays required for adequate power results in high material and labor costs that prevent wide adoption of the genetical genomics strategy outside of some well-funded laboratories. We present a method called selective transcriptional profiling that involves selecting an optimal subset of individuals to microarray from a larger set of individuals for which relatively inexpensive quantitative trait and molecular marker data are available. We show how to use microarray data from the selected individuals, along with the trait and marker data from all individuals, to identify genes whose transcript abundance is associated with a quantitative trait of interest through linkage to a trait QTL or correlation with the trait. Our methods for selection and analysis are derived within a missing data framework.

Alleles↗
PubMed2006

QTL analysis of cadmium and zinc accumulation in the heavy metal hyperaccumulator Thlaspi caerulescens.

Thlaspi caerulescens (Tc; 2n = 14) is a natural Zn, Cd and Ni hyperaccumulator species belonging to the Brassicaceae family. It shares 88% DNA identity in the coding regions with Arabidopsis thaliana (At) (Rigola et al. 2006). Although the physiology of heavy metal (hyper)accumulation has been intensively studied, the molecular genetics are still largely unexplored. We address this topic by constructing a genetic map based on AFLP markers and expressed sequence tags (ESTs). To establish a genetic map, an F(2) population of 129 individuals was generated from a cross between a plant from a Pb/Cd/Zn-contaminated site near La Calamine, Belgium, and a plant from a comparable site near Ganges (GA), France. These two accessions show different degrees of Zn and, particularly, Cd accumulation. We analyzed 181 AFLP markers (of which 4 co-dominant) and 13 co-dominant EST sequences-based markers and mapped them to seven linkage groups (LGs), presumably corresponding to the seven chromosomes of T. caerulescens. The total length of the genetic map is 496 cM with an average density of one marker every 2.5 cM. This map was used for Quantitative Trait Locus (QTL) mapping in the F(2). For Zn as well as Cd concentration in root we mapped two QTLs. Three QTLs and one QTL were mapped for Zn and Cd concentration in shoot, respectively. These QTLs explain 23.8-60.4% of the total variance of the traits measured. We found only one common locus (LG6) for Zn and Cd (concentration in root) and one common locus for shoot and root concentrations of Zn (LG1) and of Cd (LG3). For all QTLs, the GA allele increased the trait value except for two QTLs for Zn accumulation in shoot (LG1 and LG4) and one for Zn concentration in root (LG1).

Cadmium↗
PubMed2026

FM-GPT: Bayesian fine mapping for phenome-wide transcriptome-wide association studies.

Transcriptome-wide association studies (TWAS) integrate genome wide association studies with expression quantitative trait locus reference panels to identify genes associated with traits of interest. However, linkage disequilibrium and correlated gene expression can induce spurious TWAS signals, motivating fine mapping methods to prioritize putatively causal genes within associated loci. The rapid growth of large-scale phenomic resources (e.g. electronic health records (EHRs)) has shifted genetic studies from single-trait analyses to phenome-wide investigations that jointly evaluate many closely related phenotypes. We introduce FM-GPT (Fine-mapping of causal Genes for Phenome-wide Transcriptome-wide association studies), a novel Bayesian fine mapping method for prioritizing causal genes across multiple correlated phenotypes with potentially mixed outcome types (e.g., binary, count or continuous) in phenome-wide TWAS. FM-GPT performs gene-guided dimension reduction of the phenotypes and reveals pleiotropic or phenotype-specific effects of the identified genes. In simulations, FM-GPT identified true causal genes more accurately than other fine mapping methods while controlling false positives. We applied FM-GPT to two applications using data from UK Biobank: a brain-wide genetic analysis of MRI data derived regional cortical thickness measures and a phenome-wide genetic analysis of clinical phenotypes derived from EHR data. FM-GPT greatly narrowed down the set size of putatively causal genes and identified: 1. genes with pleiotropic effects on regional cortical thickness across the cerebral cortex, including five genes BCAS3, LRRC37A, NOS2P3, ARL17B and UBB on chromosome 17 regulating neuronal morphology and cortical organization; and 2. genes that influence multiple medical conditions across the circulatory, metabolic, digestive, respiratory and genitourinary systems, revealing two major axes of variation among these conditions that point to a potential trade-off in gene regulation between immune and metabolic functions. These results highlight FM-GPT's power to disentangle complex gene-phenotype relationships in large-scale phenome-wide studies, uncovering shared biological mechanisms across diverse human traits and advancing translational and comorbidity research.

Bayesian fine mapping↗
PubMed2004

Quantitative genetic analysis of glucose transporter 4 mRNA levels in baboon adipose.

OBJECTIVE: Glucose transporter 4 (GLUT4) is an insulin-responsive glucose transporter expressed in adipose tissue. A decrease of the mRNA abundance of GLUT4 in adipose tissue has been observed in conditions of insulin resistance. The objective was to conduct quantitative genetic analyses using GLUT4 mRNA levels in omental adipose tissue of baboons as a novel phenotype. RESEARCH METHODS AND PROCEDURES: A blood sample and a biopsy of omental adipose tissue were collected from 418 adult, pedigreed baboons. Total RNA was isolated from adipose tissue biopsies, and GLUT4 mRNA abundance was assayed by quantitative, real-time reverse transcription-polymerase chain reaction. Insulin and glucose were determined in fasting plasma by standard methods. Quantitative genetic analyses were conducted using GLUT4 mRNA, insulin, and glucose as quantitative traits. RESULTS: GLUT4 mRNA expression in omental adipose tissue was heritable (h(2) = 0.23, p = 0.001). Bivariate genetic analyses revealed a significant genetic correlation (rho(G)) between GLUT4 mRNA abundance and both body weight (rho(G) = 0.63, p = 0.007), BMI (rho(G) = 0.59, p = 0.02) and insulin (rho(G) = 0.72, p = 0.04). A genome scan was conducted, and a quantitative trait locus was detected on chromosome 10p12 with a logarithm of the odds ratio score of 1.1. DISCUSSION: GLUT4 mRNA abundance in omental adipose tissue has a significant genetic component. These findings suggest that expression of GLUT4 mRNA, plasma insulin levels, and body weight may be regulated by common genes.

Adipose Tissue↗
PubMed2005

Nucleotide sequence polymorphism within exon 4 of the bovine prolactin gene and its associations with milk performance traits.

Prolactin plays an important regulatory function in mammary gland development, milk secretion, and expression of milk protein genes. Hence the PRL gene is a potential quantitative trait locus and genetic marker of production traits in dairy cattle. We analysed the sequence of the PRL gene to investigate whether mutations in this sequence might be responsible for quantitative variations in milk yield and composition. Using SSCP and direct sequencing, we detected six single-nucleotide polymorphisms within a 294-bp prolactin gene fragment involving exon 4. All detected mutations were silent with respect to the amino acid sequence of the protein. PCR-RFLP genotyping of SNP 8398 R (RsaI) was used to assess allele frequencies in 186 Black-and-White cows (0.113 and 0.887 for A and G, respectively) and in 138 Jersey cows (0.706 and 0.294 for A and G, respectively). Black-and-White cows with genotype AG showed the highest milk yield, while cows with genotype GG showed the highest fat content.

Animals↗