Search results for " homozygosity"
showing 10 items of 34 documents
Genomic characterization of Algerian Guelmoise cattle and their genetic relationship with other North African populations inferred from SNP genotypin…
2018
International audience; Understanding between and within-breeds genetic variability is essential in the choice of conservation management decisions for threatened populations. In this study we assessed the genetic diversity of the Algerian Guelmoise cattle (GUE) by analyzing data on 24 GUE individuals genotyped for the Illumina BovineSNP50 BeadChipv2. We also provided a detailed description of the population structure of GUE using comparisons with 23 worldwide cattle populations, selected as being representative of African, South European and indicine populations, in addition to four North African populations. We show that GUE is an admixed population which has strong genetic similarity to …
Doubled haploid production in fruit crops
2006
The interest of fruit breeders in haploids and doubled haploids (DH), lies in the possibility of shortening the time needed to produce homozygous lines compared to conventional breeding. Haplo-diploidization through gametic embryogenesis allows single-step development of complete homozygous lines from heterozygous parents. In a conventional breeding programme, a pure line is developed after several generations of selfing. With fruit crops, characterized by a long reproductive cycle, a high degree of heterozygosity, large size, and, sometimes, self-incompatibility, there is no way to obtain haploidization through conventional methods. This paper reviews the current status of research on doub…
Genome-wide homozygosity in Maremmana cattle
2017
The current availability of large numbers of single nucleotide polymorphisms (SNPs) throughout the genome makes these markers particularly suitable for the detection of patterns of genetic diversity and of genome-wide homozygosity in animal populations. The aim of this work was to estimate genetic diversity and homozygosity in the Maremmana cattle breed. We used a sample of 149 animals (males and females) geno-typed with the BovineSNP50 v2 (54K) Illumina BeadChip. After editing for call-rate >0.9 and removing SNP unassigned or on the sex chromosomes, 128 animals and 50,814 SNPs were left. We estimated the following genetic parameters: observed and expected heterozygosity (Ho and He), minor …
Genome-wide analysis reveals the patterns of genetic diversity and population structure of 8 Italian local chicken breeds
2021
The aim of this study was to conduct a genome-wide comparative analysis of 8 local Italian chicken breeds (Ermellinata di Rovigo, Millefiori di Lonigo [PML], Polverara Bianca, Polverara Nera, Padovana, Pepoi [PPP], Robusta Lionata, and Robusta Maculata), all under a conservation plan, to understand their genetic diversity and population structure. A total of 152 animals were analyzed using the Affymetrix Axiom 600 K Chicken Genotyping Array. The levels of genetic diversity were highest and lowest in PML and PPP, respectively. The results of genomic inbreeding based on runs of homozygosity (ROH; FROH) showed marked differences among breeds and ranged from 0.161 (PML) to 0.478 (PPP). Furtherm…
Insights into Genetic Diversity, Runs of Homozygosity and Heterozygosity-Rich Regions in Maremmana Semi-Feral Cattle Using Pedigree and Genomic Data
2020
Semi-feral local livestock populations, like Maremmana cattle, are the object of renewed interest for the conservation of biological diversity and the preservation and exploitation of unique and potentially relevant genetic material. The aim of this study was to estimate genetic diversity parameters in semi-feral Maremmana cattle using both pedigree- and genomic-based approaches (FIS and FROH), and to detect regions of homozygosity (ROH) and heterozygosity (ROHet) in the genome. The average heterozygosity estimates were in the range reported for other cattle breeds (HE=0.261, HO=0.274). Pedigree-based average inbreeding (F) was estimated at 4.9%. The correlation was low between F and genomi…
Genome-Wide SNP Analysis Reveals the Population Structure and the Conservation Status of 23 Italian Chicken Breeds
2020
The genomic variability of local Italian chicken breeds, which were monitored under a conservation plan, was studied using single nucleotide polymorphisms (SNPs) to understand their genetic diversity and population structure. A total of 582 samples from 23 local breeds and four commercial stocks were genotyped using the Affymetrix 600 K Chicken SNP Array. In general, the levels of genetic diversity, investigated through different approaches, were lowest in the local chicken breeds compared to those in the commercial stocks. The level of genomic inbreeding, based on runs of homozygosity (FROH), was markedly different among the breeds and ranged from 0.121 (Valdarnese) to 0.607 (Siciliana). I…
Genome-wide detection of signatures of selection in three Valdostana cattle populations
2020
International audience; The Valdostana is a local dual purpose cattle breed developed in Italy. Three populations are recognized within this breed, based on coat colour, production level, morphology and temperament: Valdostana Red Pied (VPR), Valdostana Black Pied (VPN) and Valdostana Chestnut (VCA). Here, we investigated putative genomic regions under selection among these three populations using the Bovine 50K SNP array by combining three different statistical methods based either on allele frequencies (F-ST) or extended haplotype homozygosity (iHS and Rsb). In total, 8, 5 and 8 chromosomes harbouring 13, 13 and 16 genomic regions potentially under selection were identified by at least tw…
Production of Haploid and Doubled Haploid Lines in Nut Crops: Persian Walnut, Almond, and Hazelnut
2021
This chapter deals with induction of haploidy via parthenogenesis in Persian walnut and via microspore embryogenesis in almond and hazelnut. Haploid induction through in situ parthenogenesis using pollination with irradiated pollen to stimulate the embryogenic development of the egg cell, followed by in vitro culture of the immature haploid embryos. Microspore embryogenesis allows the induction of immature pollen grains (microspores), to move away from the normal gametophytic developmental route in the direction of the sporophytic one, yielding homozygous organisms (embryos in this case). Unlike other fruit crops (such as Citrus), regeneration of entire plants has not yet been obtained in o…
Genome-Wide Patterns of Homozygosity Reveal the Conservation Status in Five Italian Goat Populations.
2021
The application of genomic technologies has facilitated the assessment of genomic inbreeding based on single nucleotide polymorphisms (SNPs). In this study, we computed several runs of homozygosity (ROH) parameters to investigate the patterns of homozygosity using Illumina Goat SNP50 in five Italian local populations: Argentata dell’Etna (N = 48), Derivata di Siria (N = 32), Girgentana (N = 59), Maltese (N = 16) and Messinese (N = 22). The ROH results showed well-defined differences among the populations. A total of 3687 ROH segments >
Genome-wide homozygosity and risk of four non-Hodgkin lymphoma subtypes
2021
Aim: Recessive genetic variation is thought to play a role in non-Hodgkin lymphoma (NHL) etiology. Runs of homozygosity (ROH), defined based on long, continuous segments of homozygous SNPs, can be used to estimate both measured and unmeasured recessive genetic variation. We sought to examine genome-wide homozygosity and NHL risk.Methods: We used data from eight genome-wide association studies of four common NHL subtypes: 3061 chronic lymphocytic leukemia (CLL), 3814 diffuse large B-cell lymphoma (DLBCL), 2784 follicular lymphoma (FL), and 808 marginal zone lymphoma (MZL) cases, as well as 9374 controls. We examined the effect of homozygous variation on risk by: (1) estimating the fraction o…