Project description:Spatially varying environments can pose distinct costs and benefits on traits under selection, such that a beneficial trait in one environment may be counter-productive in another. As an example, lowland and highland Peromyscus maniculatus populations display divergent, locally adapted physiological mechanisms shaped by altitudinal differences in oxygen availability. Particularly, lowland mice leverage ancestral plasticity derived from acute episodic bouts of low internal oxygen triggered by causes such as blood loss, anemia or tissue ischemia. These responses can be maladaptive under persistent low-oxygen conditions, as they could lead to physiological complications such as pulmonary hypertension. Therefore, highland ancestry is associated with traits promoting chronic hypoxia tolerance. Given each population’s distinct adaptive histories and reliance on plasticity for hypoxia tolerance, we hypothesized that upon hypoxia exposure lowland mice would have a more robust epigenetic response, driving trait plasticity, than highland mice. Using DNA methylation data collected from left ventricle tissues, we show that upon hypoxia exposure, lowland mice can chemically modulate the epigenetic landscape to a greater extent than highland mice, especially at key hypoxia-relevant genes such as Egln3, a regulator of Epas1- a gene frequently targeted for positive selection at high elevation. In addition, lowland mice show greater enrichment of DNA methylation change concentrated at hypoxia-relevant biological pathways, particularly those related to Notch ligands. These findings exemplify each population’s distinct reliance on molecular plasticity driven by their unique evolutionary histories.
Project description: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:Relative expression levels of mRNAs in chicken IEL experimentally infected with EA, EM, or ET were measured at 1 to 6 days post-infection (dpi) following primary and secondary infections. One week-old chickens were uninfected (negative control) or were orally inoculated with sporulated oocysts of EA, EM, or ET. One week later, the infected chickens were challenged with an identical inoculum of the homologous parasite. Intestinal samples were collected daily from 5 birds in a treatment group at from 1 to 6 dpi following primary and secondary infections. Cecum, duodenum, and jejunum were collected from the birds challenged with E. acervulina, E. maxima, and E. tenella, respectively. Uninfected control samples and one of the 3 infection group samples were labeled with different fluorescent dyes and hybridized simultaneously on the same slide using a reference design with a dye swap protocol. Thirty seven-condition experiment, Non-infected control vs. Primary or secondary EA, EM, or ET infected IEL at 1 to 6. Biological replicates: 2 replicates with dye-switching from each infection groups. Two replicates per array.
Project description:Relative expression levels of mRNAs in chicken IEL experimentally infected with EA, EM, or ET were measured at 1 to 6 days post-infection (dpi) following primary and secondary infections. One week-old chickens were uninfected (negative control) or were orally inoculated with sporulated oocysts of EA, EM, or ET. One week later, the infected chickens were challenged with an identical inoculum of the homologous parasite. Intestinal samples were collected daily from 5 birds in a treatment group at from 1 to 6 dpi following primary and secondary infections. Cecum, duodenum, and jejunum were collected from the birds challenged with E. acervulina, E. maxima, and E. tenella, respectively. Uninfected control samples and one of the 3 infection group samples were labeled with different fluorescent dyes and hybridized simultaneously on the same slide using a reference design with a dye swap protocol.
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:Campylobacter jejuni is a common cause of diarrheal disease worldwide. Human infection typically occurs through the ingestion of contaminated poultry products. We previously demonstrated that an attenuated Escherichia coli live vaccine strain expressing the C. jejuni N-glycan on its surface reduces the Campylobacter load in more than 50% of vaccinated leghorn and broiler birds to undetectable levels (responder birds), whereas the remainder of the animals were still colonized (non-responders). To understand the underlying mechanism, we conducted 3 larger scale vaccination and challenge studies using 135 broiler birds and found a similar responder/non responder effect. The submitted data were used for a genome-wide association study of the chicken responses to glycoconjugate vaccination against Campylobacter jejuni.
2021-11-01 | GSE181619 | GEO
Project description:Parasite turnover zone at secondary contact: a new pattern in host-parasite population genetics
Project description:Beak deformities (BD) of different forms have been documented in many wild birds. The phenomenon is termed as “the largest epizootic of gross abnormalities ever recorded among wild bird populations.” Frequencies of 1% to 3% of BD (crossed beaks) were found in several indigenous chickens including Silkies, Qingyuan Partridge, Huxu, and the Beijing-You (BJY) chickens (studied here). Birds with deformed beaks have poor production performance and induce higher mortality. Therefore, BD represents an economic as well as a welfare problem. Our lab have focused and performed studies on this complex trait/disease for 7 years. Therefore, we performed a single SNP, a pathways-based genome-wide association study (GWAS), and a genome-wide CNV detection with the genotype data of 48 BD (case) and 48 normal (control) birds from Affymetrix 600K HD genotyping arrays, using ROADTRIPS, SNP ratio test (SRT) and PennCNV, respectively. To the best of our knowledge, this is the first GWAS and CNV study to investigate the mutations and genomic structural variations in the deformed and normal beaks of chickens. The findings herein are worth of further functional characterization for better understanding the genetic mechanisms of BD in chickens and wild birds as well.