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1.
Alleles at a microsatellite locus within the macrophage expressed lysozyme gene were shown to co-segregate with lysozyme activity in two half-sib families of Polish Black and White Lowland cattle. The bimodal distribution of lysozyme activities in both progeny groups is concordant with the occurrence of the alternative paternal alleles. The microsatellite is linked to a locus for high lysozyme activity that accounts for 70–95% of the phenotypic variation of both offspring groups considering the lysozyme activities of animals being older than 1 month.  相似文献   

2.
It was suggested that the rapid changes of DNA sequence and gene expression occurred at the early stages of allopolyploid formation. In this study, we revealed the microsatellite (SSR) differences between newly formed allopolyploids and their donor parents by using 21 primer sets specific for D genome of wheat. It was indicated that rapid changes had occurred in the “shock” process of the allopolyploid formation between tetraploid wheat and Aegilops tauschii. The changes of SSR flanking sequence resulted in appearance of novel bands or disappearance of parental bands. The disappearance of the parental bands showed much higher frequencies in comparison with that of appearance of novel bands. Disappearance of the parental bands was not random. The frequency of disappearance in tetraploid wheat was much higher than in Ae. tauschii, i. e. the disappearance frequency in AABB genome was much higher than in D genome. Changes of SSR flanking sequence occurred at the early stage of F1 hybrid or just after chromosome doubling. From the above results, it can be inferred that SSR flanking sequence region was very active and was amenable to change in the process of polyploidization. This suggested that SSR flanking sequence probably had special biological function at the early stage of ployploidization. The rapid and directional changes at the early stage of polyploidization might contribute to the rapid evolution of the newly formed allopolyploid and allow the divergent genomes to act in harmony.  相似文献   

3.
If natural selection chose where new mutations occur it might well favour placing them near existing polymorphisms, thereby avoiding disruption of areas that work while adding novelty to regions where variation is tolerated or even beneficial. Such a system could operate if heterozygous sites are recognised and ‘repaired’ during the initial stages of crossing over. Such repairs involve an extra round of DNA replication, providing an opportunity for further mutations, thereby raising the local mutation rate. If so, the changes in heterozygosity that occur when populations grow or shrink could feed back to modulate both the rate and the distribution of mutations. Here, I review evidence from isozymes, microsatellites and single nucleotide polymorphisms that this potential is realised in real populations. I then consider the likely implications, focusing particularly on how these processes might affect microsatellites, concluding that heterozygosity does impact on the rate and distribution of mutations.  相似文献   

4.
Associations of two alleles of the bovine major histocompatibility complex DRB3 gene (BoLA-DRB3) with lowered somatic cell score (SCS) and occurrence of disease (BoLA-DRB3.2* 16 and *23, respectively) have previously been documented. The objective of this study was to evaluate potential relationships between BoLA-DRB3 alleles with production traits, namely 305-day milk, milk fat and milk protein yield, in a population of Canadian dairy cattle (Holstein, n = 835 and Jersey, n = 66) over the course of two lactations. No significant associations were detected between BoLA alleles and production traits in Jerseys. In Holsteins, alleles *16 and *23 also did not show associations with production traits but allele *8 was significantly associated with increased 305-day milk, fat and protein yields in the previous lactation (the lactation prior to immunization with a gram negative core antigen vaccine), and with increased protein production in the subsequent (with reference to the time of immunization) lactation. Allele *22 was associated with decreased milk and protein yield in both previous and subsequent lactations. Therefore, it can be concluded that increasing or decreasing the frequency of BoLA alleles *16 and *23 to reduce SCS or increase resistance to mastitis in this population would not have adverse effects on production in this population, and that certain BoLA alleles (*8 and *22) are associated with altered production traits in Canadian Holsteins.  相似文献   

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A population of 1398 Canchim (CA) cattle was genotyped to assess the association of an insulin-like growth factor 1 (IGF1) gene microsatellite with phenotypic variation and estimated breeding values of pre-weaning, weaning and post-weaning growth traits. After an initial analysis, the IGF1 genotype only had a significant effect (P < 0.05) on birth weight (BW) and weaning weight adjusted to 240 days (WW240). For these two traits, direct and maternal breeding values were estimated using the restricted maximum likelihood (reml). Two analyses were carried out. In the first (Model I), all fixed effects were fitted. In the second (Model II), the fixed effect of the IGF1 genotype was omitted. The estimated genetic and phenotypic components of variance were similar for every trait in both models. For Model I, estimated direct and maternal heritabilities were 0.26 and 0.16 for BW and 0.23 and 0.14 for WW240 respectively. The genetic and phenotypic correlations between BW and WW240 were 0.38 and 0.38 (Model I) and 0.19 and 0.38 (Model II) respectively. Fifty animals were classified according to their direct and maternal breeding values for both traits. Spearman rank-order correlation between animal rankings in the two models was used to assess the effect of including the IGF1 genotype in the model. Non-significant values from this correlation were indicative of a difference in breeding value rankings between the two approaches. The IGF1 gene was found to be associated with phenotypic variation and breeding values in the early phase of growth.  相似文献   

8.
Carbonic anhydrase III (CA3) is an abundant muscle protein characteristic of adult type-1, slow-twitch, muscle fibres. In order to further understand the functions of the porcine CA3 protein in muscle, the temporal and spatial distributions of its gene product were analysed and the association between the presence of specific polymorphisms and carcass traits in the pig was also examined. Real-time PCR revealed that the CA3 mRNA expression showed no differences with age in skeletal muscles from Yorkshire pigs at postnatal day-1, month-2, and month-4. We provide the first evidence that CA3 is differentially expressed in the skeletal muscle of Yorkshire and Meishan pig breeds. In addition, the whole pig genomic DNA sequence of CA3 was investigated and shown to contain seven exons and six introns. Comparative sequencing of the gene from three pig breeds revealed the existence of microsatellite SJ160 in intron 5 and microsatellite SJ158 and a novel microsatellite marker that includes a tandem repeat of (TC)n in intron 4. We also determined the allele number and frequencies of the three loci in seven pig breeds and found that they are low polymorphic microsatellite markers. Statistical analysis showed that the CA3 microsatellite polymorphism was associated with dressing percentage, internal fat rate, carcass length, rib number and backfat thickness in the pig.  相似文献   

9.
Five sequence polymorphisms at the phenylalanine hydroxylase (PAH) gene locus were observed to be in tight association with specific alleles of this locus. Since these polymorphisms can be detected using polymerase chain reaction (PCR) methodology, application of a combination of these polymorphisms reduces the effort involved in PAH DNA haplotype analysis, which is needed for population genetic analysis or diagnosis of the disease status. In addition our results indicate the evolution of haplotype 3, 4 and 7 PAH alleles from a common ancestor, whereas PAH haplotypes 5, 6, and 11 arose form another common ancestor allele. These data reveal that two of the polymorphisms investigated originated before the separation of races.  相似文献   

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The bovine oxidized LDL receptor 1 (OLR1) was chosen as a candidate gene for association tests with milk composition traits. Genotyping of 773 Italian Brown Swiss for a SNP at position 8232 in OLR1 (NW_215807:g.8232C>A) revealed a frequency of 0.95 for the g.8232C allele. The University of Wisconsin Holstein resource population was genotyped for the OLR1 NW_215807:g.[7160C>T; 7161A>G; 8232C>A] SNPs, and four haplotypes were inferred based on the genotypes of sires and their daughters. Oxidized LDL receptor 1 haplotypes were significantly associated with fat percentage (P = 0.0015). Haplotype [C; A; C] was associated with a significant increase in fat percentage when compared with the other haplotypes.  相似文献   

12.
Quantitative trait loci (QTL) affecting health and milk production traits were studied in seven large half-sib US Holstein families by using the granddaughter design. Genotyping for 16 markers was completed and marker allele differences within and pooled-across families were analysed. Potential QTL were identified for somatic cell score (SCS), fat yield, fat percentage, protein yield and protein percentage. Three markers (BM203, BM4505 and BM2078) were associated with significant effects for different traits and, after further analysis, may be useful in marker-assisted selection in specific families. Comparisons between these data and previously identified QTL support the location of a QTL for milk yield and protein yield on chromosome 21.  相似文献   

13.
We examined the evolutionary processes contributing to genetic diversity at the major histocompatibility complex (MHC) class II DRB locus in chamois (Rupicapra spp., subfamily Caprinae). We characterised the pattern of intragenic recombination (or homologous gene conversion) and quantified the amount of recombination in the genealogical history of the two chamois species, Pyrenean chamois (Rupicapra pyrenaica) and Alpine chamois (Rupicapra rupicapra). We found evidence for intragenic recombination, and the estimated amount of population recombination suggests that recombination has been a significant process in generating DRB allelic diversity in the genealogical history of the genus Rupicapra. Moreover, positive selection appears to act on the same peptide-binding residues in both analysed chamois species, but not in identical intensity. Recombination coupled with positive selection drives the rapid evolution at the peptide-binding sites in the MHC class II DRB gene. Many chamois MHC class II DRB alleles are thus much younger than previously assumed.  相似文献   

14.
We developed and characterized 10 highly polymorphic microsatellite loci from an SSR‐enriched genomic DNA library of the common earthworm (Lumbricus terrestris L). Characterization of these loci using 32 individuals revealed high levels of genetic diversity, five to 18 alleles per locus and a high observed and expected heterozygosity. These loci will be used for paternity analysis and population genetic studies of the co‐evolution between L. terrestris and its parasites.  相似文献   

15.
The evolutionary conservation of mismatch repair and Saccharomyces cerevisiae as a model system have been exploited for monitoring the influence of everyday beverages and the antineoplastic agent, hydroxyurea, on the stability of regions of highly repetitive DNA known as microsatellites. Two different reporter systems are compared for sensitivity and reproducibility by measuring the extent of frame slippage events occurring in microsatellite regions in wild-type and mismatch repair-compromised yeast strains. Increased frame slippage results in increased reporter gene expression and hence represents instability within the repetitive region, whereas a decrease or no significant change indicates the faithful replication of the original assay plasmid, suggesting a beneficial or neutral effect of the test component. A significant outcome of this study was the identification of the protective influence exerted by the green tea catechin (-)-epigallocatechin-3-gallate (EGCG) against microsatellite instability, which is in agreement with the hypothesis that EGCG is the major chemopreventive ingredient of green tea. Immunological detection can also be used in conjunction with the green fluorescent protein (GFP) version of the assay system to identify compounds, such as hydroxyurea, which increased microsatellite instability. The system has the potential for development as a high-throughput assay for wider application.  相似文献   

16.
A European eel (Anguilla anguilla) expressed sequence tag database consisting of 795 contigs and 4008 singletons was screened for microsatellites sequences. Primers were designed to amplify 96 repeats, of which 86 gave good quality amplification products. Twenty-eight microsatellites were selected for further microsatellite genotyping. Only two loci were found to be monomorphic; out of the 26 polymorphic loci, number of alleles per locus ranged from two to 14, while the observed and expected heterozygosities ranged from 0.05 to 0.93, and from 0.05 to 0.95, respectively. All 28 primer sets tested revealed positive amplification in American eel (Anguilla rostrata).  相似文献   

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Association studies using linkage disequilibrium (LD) between candidate loci and nearby markers have been proposed to identify susceptibility genes for complex diseases. We analyzed polymorphisms of microsatellites (MSs) and LD patterns of the regions in which candidate genes related to the Th1 immune response have been annotated and attempted to identify a susceptibility gene for sarcoidosis in a marker-based association study. Nineteen MSs were identified in six Th1-related genes (IFNGR1, IFNGR2, IL12RB1, IL12RB2, STAT1 and STAT4) and then eight were further characterized as useful polymorphic markers. Most of these MSs showed LD with single nucleotide polymorphisms (SNPs) on both 5 and 3 ends of these candidate genes, in which r2 values between at least one of the MS marker alleles and the SNPs were higher than 0.1. A significant association with one MS allele near STAT4 was shown and a cluster of SNPs in LD with the MS marker was associated with sarcoidosis. These results suggest that association studies using not only SNPs but also multi-allelic MS within or near candidate loci would be useful markers to search for a disease susceptibility gene, especially in populations with unknown LD structure.  相似文献   

19.
Ning QL  Ma XD  Jiao LZ  Niu XR  Li JP  Wang B  Zhang H  Ma J 《遗传》2012,34(3):307-314
研究表明位于染色体8p21.3区域的EGR3(Early growth response 3)是精神分裂症(Schizophrenia)的重要易感基因,然而,仍有两个病例-对照研究未能验证上述发现。为了研究EGR3基因在我国患者中是否与疾病关联,文章在中国汉族的核心家系中选择EGR3基因座位上的5个SNPs位点(rs1996147、rs1877670、rs3750192、rs35201266和rs7009708)进行基因分型和传递不平衡检验(Transmission disequilibrium test,TDT)。结果表明遗传标记rs1996147和rs3750192分别显示出显著的传递不平衡(2>4.40,P<0.05)。在连锁不平衡分析中,由2个(rs3750192和rs35201266)、3个(rs1877670、rs3750192和rs7009708)以及4个(rs1996147、rs1877670、rs3750192和rs7009708)SNPs位点构建的单倍型均显示与精神分裂症显著性关联(2>7.10,整体P<0.05)。总之,EGR3基因与中国汉族人群精神分裂症遗传易感性相关,后续关于EGR3基因进一步的功能研究将会更好的帮助我们了解该基因在疾病病理学机制中的作用。  相似文献   

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