Genome Resequencing Identifies Unique Adaptations of Tibetan Chickens to Hypoxia and High-dose Ultraviolet Radiation in High-altitude Environments
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ABSTRACT: Tibetan chickens exhibit specific adaptations to high-altitude conditions compared with their lowland counterparts. To illustrate the genetic mechanisms of such adaptations in highland chickens, the genomes of four highland and four lowland chicken populations were resequenced. Our results showed that genes under positive selection in highland populations were related to cardiovascular and respiratory system development, DNA repair, response to radiation, inflammation, and immune response, indicating a strong adaptation to oxygen scarcity and high-intensity solar radiation. The distribution of allele frequencies of non-synonymous single nucleotide polymorphisms between highland and lowland populations was also analyzed by chi-square test. The results showed that several differentially distributed genes with missense mutations were enriched in several functional categories, especially in blood vessel development, which were related to adaptations to hypoxia and intense radiation. RNA sequencing also revealed that several differentially expressed genes were enriched in gene ontology terms related to blood vessel and respiratory system development. Additionally, an evident admixture found in Tibetan chickens suggested a history of introgression from lowland gene pools. Overall, our data provided new insights into the unique adaptation of highland animals to extreme environments.
Project description:In this study, methylated DNA immunoprecipitation and high-throughput sequencing (MeDIP-seq) was used to provide an atlas of DNA methylomes in the heart tissue of hypoxic highland Tibetan and lowland Chahua chicken embryos.A total of 31.2 gigabases (Gb) of sequence data were generated from six MeDIP-seq libraries. We identified 1049 differentially methylated regions (DMRs) and 695 related differentially methylated genes (DMGs) between the two chicken breeds. The DMGs were involved in vascular smooth muscle contraction, VEGF signaling pathway, calcium signaling pathway, and other hypoxia related pathways. Five candidate genes that had low methylation (EDNRA, EDNRB, BMPR1B, BMPRII, and ITGA2) might have key regulatory functions for hypoxia adaptation in Tibetan chicken embryos. Our study provides significant explanations for the functions of genes and their epigenetic regulation for hypoxic adaptation in Tibetan chickens.
Project description:In this study, RNA-seq technique was used to identify differentially expressed genes (DEGs) in cardiac muscle of the Tibetan pigs raised at highland (TH), Tibetan pigs raised at lowland (TL), Yorkshire pigs raised at highland (YH) and Yorkshire raised at lowland (YL). We obtained 551M clean reads and detected 18585 genes that were expressed in the eight heart samples. According to a standard of fold-change (FC>2 or FC <0.5) and difference significant (P<0.05), obtained 299, 169, 242 and 368 of significantly differentially expressed genes (DEGs) respectively in TH vs.YH, TH vs.TL, TL vs.YL and YH vs.YL. GO and pathways analysis for DEGs results showed enrichment in HIF-1 signaling pathway, and hypertrophic cardiomyopathy (Hypertrophic cardiomyopathy (HCM), cardiovascular development, immunity, DNA damage and other biological functions. Eight DEGs were randomly selected to validate the veracity of RNA-seq and using real-time PCR. The results showed that the expression corresponds to the trend in RNA-seq, hence the deep-sequencing methods were feasible and efficient. This study expanded the number of hypoxic-adaptation-related genes in pig and indicated that the expression patterns of hypoxia-related genes are significantly altered in the Tibetan pig. DEGs may play important roles in hypoxic adaptation after migration to hypoxic environments.
Project description:Background/Aims: Tibetan chickens, a unique plateau breed, have good performances to adapt to high-altitude hypoxic environments. A number of positively selected genes have been reported in Tibetan chickens; however, the mechanisms of gene expression for hypoxia adaptation are not fully understood. Methods: Eggs from Tibetan (TC) and Chahua (CH) chickens were incubated under hypoxic and normoxic conditions, and vessel density index (VDI) in the chorioallantoic membrane (CAM) of embryos was measured. Meanwhile, Transcriptomic and proteomic analyses of CAM tissues were performed in TC and CH embryos under hypoxic incubation using RNA-seq and iTRAQ. Results: We found that the vessel density index (VDI) in CAM of TCs was lower than in CHs under hypoxia incubation. In the transcriptomic and proteomic analyses, 160 differentially expressed genes (DEGs) and 387 differentially expressed proteins (DEPs) that were mainly enriched in angiogenesis, vasculature development, blood vessel morphogenesis, blood circulation, renin-angiotensin system, and HIF-1 and VEGF signaling pathways. Twenty-six genes involved in angiogenesis and blood circulation, two genes involved in ion transport, and six genes that regulated energy metabolism were identified as candidate functional genes in regulating hypoxic adaption of chicken embryos. Conclusion: Combination of transcriptomic and proteomic data revealed several key candidate regulators and pathways that might play high-priority roles in the hypoxic adaptation of Tibetan chickens by regulating angiogenesis and promoting blood circulation, thus explaining the blunt responses to hypoxic conditions on CAM angiogenesis in Tibetan chicken embryos. This research provided insights into the molecular mechanism of hypoxia adaptation in Tibetan chickens.
Project description:Tibetan chickens, a unique plateau breed, have good performances to adapt to high-altitude hypoxic environments. A number of positively selected genes have been reported in Tibetan chickens; however, the mechanisms of gene expression for hypoxia adaptation are not fully understood. In the present study, eggs from Tibetan (TC) and Chahua (CH) chickens were incubated under hypoxic and normoxic conditions, and vascularization in the chorioallantoic membrane (CAM) of embryos was observed. We found that the vessel density index (VDI) in CAM of TCs was lower than in CHs under hypoxia incubation.Proteomic analyses of CAM tissues were performed in TC and CH embryos under hypoxic incubation using iTRAQ. We obtained 387 differentially expressed proteins (DEPs) that were mainly enriched in angiogenesis, vasculature development, blood vessel morphogenesis, blood circulation, renin-angiotensin system, and HIF-1 and VEGF signaling pathways. Twenty-six genes involved in angiogenesis and blood circulation, two genes involved in ion transport, and six genes that regulated energy metabolism were identified as candidate functional genes in regulating hypoxic adaption of chicken embryos. Therefore, this research provided insights into the molecular mechanism of hypoxia adaptation in Tibetan chickens.
Project description:We used the scRNA-seq to characterize disease-related heterogeneity within cell populations of macrophages/monocytes in the bronchoalveolar lavage fluid from West Highland white terriers either healthy or affected with canine idioapthic pulmonary fibrosis. The disease is still not well understood, occurs in old West Highland white terriers and results from deposition of fibrotic tissue in the lung parenchyma causing respiratory failure.
Project description:In this study, miRNA-seq technique was used to identify differentially expressed miRNAs (DE miRNAs) in cardiac muscle of the Tibetan pig (TP) and Yorkshire pig (YP), which were both raised in highland environments. We obtained 108 M clean reads and 372 unique miRNAs that included 210 known pre-miRNAs and 162 novel pre-miRNAs. In addition, 20 DE miRNAs, including 10 upregulated and 10 downregulated miRNAs, were identified by comparing TP and YP. Based on the expression abundance and differentiation between the two populations, we predicted their targets, and KEGG pathway analyses suggested that DE miRNAs between the Tibetan pigs and Yorkshire pigs are involved in hypoxia-related pathways, such as the MAPK, mTOR, and VEGF signaling pathways, cancer-related signaling pathways, etc. Five DE miRNAs were randomly selected to validate the veracity of miRNA-seq using real-time PCR. The results showed that the expression corresponds to the trend in miRNA-seq, hence the deep-sequencing methods were feasible and efficient. This study expanded the number of hypoxic-adaptation-related miRNAs in pig and indicated that the expression patterns of hypoxia-related miRNAs are significantly altered in the Tibetan pig. DE miRNAs may play important roles in hypoxic adaptation after migration to hypoxic environments. mRNA profiles of 6-month old Tibetan pig (TP) and Yorkshire pig (YP) were generated by deep sequencing, in duplicate, using Hiseq 2000.
Project description:Adaptation to hypoxia is a complicated and important physiological course for organisms, but the genetic mechanism underlying the adaptation is not fully understood yet. Tibetan Chicken (T), an indigenous chicken breed in China which inhabit in high areas with an altitude above 2,900 meters. Shouguang Chicken(S) and Dwarf Recessive White Chicken (DRW), two lowland chicken breeds, were used as control groups. The heart was the first functional organ to develop during the embryonic development. Furthermore, the heart is an efficient energy converter utilizing the most appropriate fuel for a given environment. Therefore, GeneChip® Chicken Genome Array was employed to identify the differentially expressed genes in embryonic hearts of Tibetan Chicken and two lowland chicken breeds in both hypoxic and normoxic incubating environments with a genome wide profile. Keywords: stress response
Project description:Background: Tibetan chicken, a unique plateau breed, has a suite of adaptive features that enable it to tolerate the high-altitude hypoxic environment. HIF‐1α (hypoxia inducible factor 1 subunit alpha) is a crucial mediator of the cellular response to hypoxia. HIF‐1α maintains oxygen homeostasis by inducing glycolysis, erythropoiesis, and angiogenesis; however, the target genes involved in adaptive responses to hypoxia in animals and birds of plateaus are still unclear. Results: We used ChIP-seq to map HIF‐1α binding regions in chorioallantoic membrane (CAM) tissue of chicken embryos, and identified 752 HIF-1α target genes (TG), of which 112 were differentially expressed target genes (DTGs) between the two breeds. We found that eight genes (PTK2, GPNMB, CALD1, SLC25A1, SPRY2, NUPL2, RANBPL, and CBWD1) play important roles in hypoxic adaption by regulating blood vessel development, energy metabolism through angiogenesis, vascular smooth muscle contraction, and various hypoxia-related signaling pathways (including VEGF and MAPK) in Tibetan chickens during embryonic development. Conclusions: This study enhances our understanding of the molecular mechanisms of hypoxic adaptation in Tibetan chickens and provides new insights into adaptation to hypoxia in humans and other species living at high altitude.
Project description:Adaptation to hypoxia is a complicated and important physiological course for organisms, but the genetic mechanism underlying the adaptation is not fully understood yet. Tibetan Chicken (T), an indigenous chicken breed in China which inhabit in high areas with an altitude above 2,900 meters. Shouguang Chicken(S) and Dwarf Recessive White Chicken (DRW), two lowland chicken breeds, were used as control groups. The heart was the first functional organ to develop during the embryonic development. Furthermore, the heart is an efficient energy converter utilizing the most appropriate fuel for a given environment. Therefore, GeneChip® Chicken Genome Array was employed to identify the differentially expressed genes in embryonic hearts of Tibetan Chicken and two lowland chicken breeds in both hypoxic and normoxic incubating environments with a genome wide profile. Experiment Overall Design: To obtain general expression profiles of embryonic hearts in Tibetan Chicken(T), Dwarf Recessive White Chicken (DRW)and Shouguang Chicken (S)in hypoxia and normoxia, the fertilized full sib eggs of all the three chicken breeds were incubated under two different conditions. The heart was isolated from all the three chicken breeds under the two different conditions for RNA extraction and hybridization on Affymetrix microarrays.
Project description:In this study, miRNA-seq technique was used to identify differentially expressed miRNAs (DE miRNAs) in cardiac muscle of the Tibetan pig (TP) and Yorkshire pig (YP), which were both raised in highland environments. We obtained 108 M clean reads and 372 unique miRNAs that included 210 known pre-miRNAs and 162 novel pre-miRNAs. In addition, 20 DE miRNAs, including 10 upregulated and 10 downregulated miRNAs, were identified by comparing TP and YP. Based on the expression abundance and differentiation between the two populations, we predicted their targets, and KEGG pathway analyses suggested that DE miRNAs between the Tibetan pigs and Yorkshire pigs are involved in hypoxia-related pathways, such as the MAPK, mTOR, and VEGF signaling pathways, cancer-related signaling pathways, etc. Five DE miRNAs were randomly selected to validate the veracity of miRNA-seq using real-time PCR. The results showed that the expression corresponds to the trend in miRNA-seq, hence the deep-sequencing methods were feasible and efficient. This study expanded the number of hypoxic-adaptation-related miRNAs in pig and indicated that the expression patterns of hypoxia-related miRNAs are significantly altered in the Tibetan pig. DE miRNAs may play important roles in hypoxic adaptation after migration to hypoxic environments.