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Background Understanding how evolutionary forces relating to climate have shaped the patterns of genetic variation within and between species is a fundamental pursuit in biology. Iranian indigenous chickens have evolved genetic adaptations to their local environmental conditions, such as hot and arid regions. In the present study, we provide a population genome landscape of genetic variations in 72 chickens representing nine Iranian indigenous ecotypes (Creeper, Isfahan, Lari, Marand, Mashhad, Naked neck, Sari, Shiraz and Yazd) and two commercial lines (White Leghorn and Arian). We further performed comparative population genomics to evaluate the genetic basis underlying variation in the adaptation to hot climate and immune response in indigenous chicken ecotypes. To detect genomic signatures of adaptation, we applied nucleotide diversity (θπ) and FST statistical measurements, and further analyzed the results to find genomic regions under selection for hot adaptation and immune response-related traits. Results We assessed the relationship between the genetic diversity of indigenous chicken ecotypes and their genetic distances to two different commercial lines. The results of genetic structure analysis revealed clustering of indigenous chickens in agreement with their geographic origin. Among all studied chicken groups, the highest level of linkage disequilibrium (LD) (~ 0.70) was observed in White Leghorn group at marker pairs distance of 1 Kb. The results from admixture analysis demonstrated evidence of shared ancestry between Arian individuals and indigenous chickens, especially those from the north of the country. Our search for potential genomic regions under selection in indigenous chicken ecotypes revealed several immune response and heat shock protein-related genes, such as HSP70, HSPA9, HSPH1, HSP90AB1 and PLCB4 that have been previously unknown to be involved in environmental-adaptive traits. In addition, we found some other candidate loci on different chromosomes probably related with hot adaptation and immune response-related traits. Conclusions The work provides crucial insights into the structural variation in the genome of Iranian indigenous chicken ecotypes, which up to now has not been genetically investigated. Several genes were identified as candidates for drought, heat tolerance, immune response and other phenotypic traits. These candidate genes may be helpful targets for understanding of the molecular basis of adaptation to hot environmental climate and as such they should be used in chicken breeding programs to select more efficient breeds for desert climate.

Background Breast cancer is one of the most important causes of mortality in the world, and Tamoxifen therapy is known as a medication strategy for estrogen receptor-positive breast cancer. In current study, two hypotheses of Tamoxifen consumption in breast cancer cell line (MCF7) were investigated. First, the effect of Tamoxifen on genes expression profile at transcriptome level was evaluated between the control and treated samples. Second, due to the fact that Tamoxifen is known as a mutagenic factor, there may be an association between the alterations of genetic variants and Tamoxifen treatment, which can impact on the drug response. Methods In current study, the whole-transcriptome (RNA-seq) dataset of four investigations (19 samples) were derived from European Bioinformatics Institute (EBI). At transcriptome level, the effect of Tamoxifen was investigated on gene expression profile between control and treatment samples. Moreover, Tamoxifen is known as a mutagenic factor, therefore, its contribution to alterations of genetic variants and drug response were examined. Results Results achieved from RNA-seq analysis indicated the contribution of several candidate genes to tumor suppression process and consequently, the achievement of an effective treatment. For instance, XIAP-associated factor 1 (XAF1) was reported as an up-regulated gene under Tamoxifen therapy. XAF1 is a tumor suppressor that contributes to the apoptosis induction and tumor growth inhibition along with TP53. Results of gene ontology enrichment analysis of differential gene expressions indicated that most of them could considerably lead to the cell death, apoptosis, and negative regulation of proteolysis process. Findings achieved from evaluating Tamoxifen mutagenicity effect on drug response was not confirmed perfectly. The most reported candidate genes, which were related to differential genetic variants between control and treated samples, played the oncogene and tumor suppressor dual roles and also their exact roles in breast cancer were not investigated precisely. Conclusion At transcriptome level, Tamoxifen consumption in MCF7 cell line could be associated with candidate genes and biological pathways that contribute to the apoptosis, proteolysis, and tumor suppression. The mutagenicity effect of Tamoxifen and its contribution to drug response was not confirmed perfectly.

Objective Navigation is the most important feature of homing pigeons, however no integrated response to genetic mechanism of navigation has been reported. The generated data herein represent whole-genome resequencing data for homing pigeon and three other breeds of rock pigeons. Selective sweep analysis between homing pigeon and other breeds of rock pigeon can provide new insight about identification of candidate genes and biological pathways for homing pigeon ability. Data description Whole-genomes sequence data related to 95 birds from four breeds of rock pigeons including, 29 feral pigeons, 24 Shiraz tumblers, 24 Persian high flyers and 18 homing pigeons were provided. More than 6.94 billion short reads with coverage (average ≈7.50 x) and 407.1 Gb data were produced. Whole genome sequencing was carried out on the Illumina Hiseq 2000 platform using a 350 bp library size and 150 bp paired-end read lengths. The whole genome sequencing data have been submitted at the NCBI SRA Database (PRJNA532675). The presented data set can provide useful genomic information to explain the genetic mechanism of navigation ability of homing pigeons and also testing other genetic hypothesis by genomic analysis.

Background Hypoxia refers to the condition of low oxygen pressure in the atmosphere and characterization of response to hypoxia as a biological complex puzzle, is challenging. Previously, we carried out a comparative genomic study by whole genome resequencing of highland and lowland Iranian native chickens to identify genomic variants associated with hypoxia conditions. Based on our previous findings, we used chicken as a model and the identified hypoxia-associated genes were converted to human’s orthologs genes to construct the informative gene network. The main goal of this study was to visualize the features of diseases due to hypoxia-associated genes by gene network analysis. Results It was found that hypoxia-associated genes contained several gene networks of disorders such as Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and cancers. We found that biological pathways are involved in mitochondrion dysfunctions including peroxynitrous acid production denoted in brain injuries. Lewy body and neuromelanin were reported as key symptoms in Parkinson disease. Furthermore, calmodulin, and amyloid precursor protein were detected as leader proteins in Alzheimer’s diseases. Dexamethasone was reported as the candidate toxic drug under the hypoxia condition that implicates diabetes, osteoporosis, and neurotoxicity. Our results suggested DNA damages caused by the high doses of UV radiation in high-altitude conditions, were associated with breast cancer, ovarian cancer, and colorectal cancer. Conclusions Our results showed that hypoxia-associated genes were enriched in several gene networks of disorders including Parkinson, Alzheimer, cardiomyopathy, drug toxicity, and different types of cancers. Furthermore, we suggested, UV radiation and low oxygen conditions in high-altitude regions may be responsible for the variety of human diseases.

Native chickens are endangered genetic resources that are kept by farmers for different purposes. Native chickens distributed in a wide range of altitudes, have developed adaptive mechanisms to deal with hypoxia. For the first time, we report variants associated with high-altitude adaptation in Iranian native chickens by whole genome sequencing of lowland and highland chickens. We found that these adaptive variants are involved in DNA repair, organs development, immune response and histone binding. Amazingly, signature selection analysis demonstrated that differential variants are adaptive in response to hypoxia and are not due to other evolutionary pressures. Cellular component analysis of variants showed that mitochondrion is the most important organelle for hypoxia adaptation. A total of 50 variants was detected in mtDNA for highland and lowland chickens. High-altitude associated with variant discovery highlighted the importance of COX3, a gene involved in cell respiration, in hypoxia adaptation. The results of study suggest that MIR6644-2 is involved in hypoxia and high-altitude adaptations by regulation of embryo development. Finally, 3877 novel SNVs including the mtDNA ones, were submitted to EBI (PRJEB24944). Whole-genome sequencing and variant discovery of native chickens provided novel insights about adaptation mechanisms and highlights the importance of valuable genomic variants in chickens.

Background Species domestication is generally characterized by the exploitation of high-impact mutations through processes that involve complex shifting demographics of domesticated species. These include not only inbreeding and artificial selection that may lead to the emergence of evolutionary bottlenecks, but also post-divergence gene flow and introgression. Although domestication potentially affects the occurrence of both desired and undesired mutations, the way wild relatives of domesticated species evolve and how expensive the genetic cost underlying domestication is remain poorly understood. Here, we investigated the demographic history and genetic load of chicken domestication. Results We analyzed a dataset comprising over 800 whole genomes from both indigenous chickens and wild jungle fowls. We show that despite having a higher genetic diversity than their wild counterparts (average π, 0.00326 vs. 0.00316), the red jungle fowls, the present-day domestic chickens experienced a dramatic population size decline during their early domestication. Our analyses suggest that the concomitant bottleneck induced 2.95% more deleterious mutations across chicken genomes compared with red jungle fowls, supporting the “cost of domestication” hypothesis. Particularly, we find that 62.4% of deleterious SNPs in domestic chickens are maintained in heterozygous states and masked as recessive alleles, challenging the power of modern breeding programs to effectively eliminate these genetic loads. Finally, we suggest that positive selection decreases the incidence but increases the frequency of deleterious SNPs in domestic chicken genomes. Conclusion This study reveals a new landscape of demographic history and genomic changes associated with chicken domestication and provides insight into the evolutionary genomic profiles of domesticated animals managed under modern human selection.

Despite the substantial role that chickens have played in human societies across the world, both the geographic and temporal origins of their domestication remain controversial. To address this issue, we analyzed 863 genomes from a worldwide sampling of chickens and representatives of all four species of wild jungle fowl and each of the five subspecies of red jungle fowl (RJF). Our study suggests that domestic chickens were initially derived from the RJF subspecies Gallus gallus spadiceus whose present-day distribution is predominantly in southwestern China, northern Thailand and Myanmar. Following their domestication, chickens were translocated across Southeast and South Asia where they interbred locally with both RJF subspecies and other jungle fowl species. In addition, our results show that the White Leghorn chicken breed possesses a mosaic of divergent ancestries inherited from other subspecies of RJF. Despite the strong episodic gene flow from geographically divergent lineages of jungle fowls, our analyses show that domestic chickens undergo genetic adaptations that underlie their unique behavioral, morphological and reproductive traits. Our study provides novel insights into the evolutionary history of domestic chickens and a valuable resource to facilitate ongoing genetic and functional investigations of the world’s most numerous domestic animal.

The homing pigeon was selectively bred from the domestic pigeon for a homing ability over long distances, a very fascinating but complex behavioral trait. Here, we generate a total of 95 whole genomes from diverse pigeon breeds. Comparing the genomes from the homing pigeon population with those from other breeds identifies candidate positively selected genes, including many genes involved in the central nervous system, particularly spatial learning and memory such as LRP8. Expression profiling reveals many neuronal genes displaying differential expression in the hippocampus, which is the key organ for memory and navigation and exhibits significantly larger size in the homing pigeon. In addition, we uncover a candidate gene GSR (encoding glutathione-disulfide reductase) experiencing positive selection in the homing pigeon. Expression profiling finds that GSR is highly expressed in the wattle and visual pigment cell layer, and displays increased expression levels in the homing pigeon. In vitro, a magnetic field stimulates increases in calcium ion concentration in cells expressing pigeon GSR. These findings support the importance of the hippocampus (functioning in spatial memory and navigation) for homing ability, and the potential involvement of GSR in pigeon magnetoreception.

Genetic structure and genetic diversity levels of indigenous Iranian sheep breeds are not clear, despite the interest this region has in itself as an important center for domestication of livestock. Early population genetic studies have reported high levels of diversity among Iranian sheep breeds until recently, when high admixture levels and genetic homogeneity have been detected. The rapid reduction of diversity observed in Iranian breeds might be due to an increasing trend of intensive crossbreeding practices or even total replacement of native breeds by highly specialized and productive ones. From a conservative perspective, this situation is highly concerning; thus, it might be wise to consider a conservation program in Iran to preserve the original genetic diversity in native sheep breeds. In this study, a total of 1065 animals with the purest morphological features representing 24 Iranian indigenous sheep breeds were sampled, corresponding to ancestral breed diversity. These samples were genotyped for 17 microsatellite loci in order to (1) determine the native ancestral diversity of Iranian breeds, (2) define the degree of genetic relationship among studied breeds, and (3) assess conservation priorities among defined groups. Our results showed no recent loss of diversity, but high genetic diversity levels for indigenous sheep breeds in Iran. Indeed, the analysis of conservation priorities pointed out the importance of 8 breeds for maintaining Iranian sheep breeds' maximum genetic diversity. Thus, under a genetic perspective, these 8 breeds should be the ones included into conservation programs for restocking endangered areas.

Fars native chicken (FNC) is utilized as a food source, and plays a critical role in earning money in rural areas. However, little attention has been paid to FNC at molecular level and its genetic background is unknown for organizing the breeding programs. For the first time, herein, the effect of Ovocalyxin-32 (OCX-32) variant on egg production traits was investigated. OCX-32 protein plays role in minerals deposition and completion of eggshell. 400 blood samples were collected and a 390-bp fragment including exon 3 in OCX-32 gene (c.193A > C) was amplified and genotyped using RFLP-PCR technique. The bioinformatics analysis showed that the studied SNP is messiness mutation and leads to the substitution of Histidine with Asparagine in protein structure. Two genotypes including AA and AC were identified and effect of genotypes on the age at first egg was significant. Phylogeny analysis indicated that the OCX-32 gene sequences of FNC and Coturnix japonica are genetically categorized into the same group. The gene network analysis showed that there was association among OCX-32 and other important candidate genes affecting body size, digestibility and egg proteins. Therefore, OCX-32 could contribute to overall egg production in chickens.

Single nucleotide polymorphisms (SNPs) are DNA sequence variations that occur when a single nucleotide: adenine (A), thymine (T), cytosine (C) or guanine (G) in the genome sequence is altered. Traditional and high throughput methods are two main strategies for SNPs genotyping. The SNPs genotyping technologies provide powerful resources for animal breeding programs.Genomic selection using SNPs is a new tool for choosing the best breeding animals. In addition, the high density maps using SNPs can provide useful genetic tools to study quantitative traits genetic variations. There are many sources of SNPs and exhaustive numbers of methods of SNP detection to be considered. For many traits in farm animals, the rate of genetic improvement can be nearly doubled when SNPs information is used compared to the current methods of genetic evaluation. The goal of this review is to characterize the SNPs genotyping methods and their applications in farm animals breeding.