The concept of successional trajectories describes how small differences in initial community composition can magnify through time and lead to significant differences in mature communities. For many animals, the types and sources of early-life exposures to microbes have been shown to have significant and long-lasting effects on the community structure and/or function of the microbiome. In modern commercial poultry production, chicks are reared as a single age cohort and do not directly encounter adult birds. This scenario is likely to initiate a trajectory of microbial community development that is significantly different than non-industrial settings where chicks are exposed to a much broader range of environmental and fecal inocula; however, the comparative effects of these two scenarios on microbiome development and function remain largely unknown. In this work, we performed serial transfers of cecal material through multiple generations of birds to first determine if serial transfers exploiting the ceca in vivo, rather than the external environment or artificial incubations, can produce a stable microbial community. Subsequently, we compared microbiome development between chicks receiving this passaged, i.e. host-selected, cecal material orally, versus an environmental inoculum, to test the hypothesis that the first exposure of newly hatched chicks to microbes determines early GI microbiome structure and may have longer-lasting effects on bird health and development. Cecal microbiome dynamics and bird weights were tracked for a two-week period, with half of the birds in each treatment group exposed to a pathogen challenge at 7 days of age. We report that: i) a relatively stable community was derived after a single passage of transplanted cecal material, ii) this cecal inoculum significantly but ephemerally altered community structure relative to the environmental inoculum and PBS controls, and iii) either microbiome transplant administered at day-of-hatch appeared to have some protective effects against pathogen challenge relative to uninoculated controls. Differentially abundant taxa identified across treatment types may inform future studies aimed at identifying strains associated with beneficial phenotypes.

The concept of successional trajectories describes how small differences in initial community composition can magnify through time and lead to significant differences in mature communities. For many animals, the types and sources of early-life exposures to microbes have been shown to have significant and long-lasting effects on the community structure and/or function of the microbiome. In modern commercial poultry production, chicks are reared as a single age cohort and do not directly encounter adult birds. This scenario is likely to initiate a trajectory of microbial community development that is significantly different than non-industrial settings where chicks are exposed to a much broader range of environmental and fecal inocula; however, the comparative effects of these two scenarios on microbiome development and function remain largely unknown. In this work, we performed serial transfers of cecal material through multiple generations of birds to first derive a stable source of inoculum. Subsequently, we compared microbiome development between chicks receiving this passaged cecal material, versus an environmental inoculum, to test the hypothesis that the first exposure of newly hatched chicks to microbes determines early GI microbiome structure and may have longer-lasting effects on bird health and development. Cecal microbiome dynamics and bird weights were tracked for a two-week period, with half of the birds in each treatment group exposed to a pathogen challenge at 7d of age. We report that: i) a relatively stable community was derived after a single passage of transplanted cecal material, ii) this cecal inoculum significantly but ephemerally altered community structure relative to the environmental inoculum and PBS controls, and iii) either microbiome transplant administered at day-of-hatch appeared to have some protective effects against pathogen challenge relative to uninoculated controls. Differentially abundant taxa were identified across treatment types and may inform future studies and identify strains associated with beneficial phenotypes.

Discovering genetic biomarkers associated with disease resistance and enhanced immunity is critical to developing advanced strategies for controlling viral and bacterial infections in different species. Macrophages, important cells of innate immunity, are directly involved in cellular interactions with pathogens, the release of cytokines activating other immune cells and antigen presentation to cells of the adaptive immune response. IFNγ is a potent activator of macrophages and increased production has been associated with disease resistance in several species. This study characterizes the molecular basis for dramatically different nitric oxide production and immune function between the B2 and the B19 haplotype chicken macrophages.A large-scale RNA sequencing approach was employed to sequence the RNA of purified macrophages from each haplotype group (B2 vs. B19) during differentiation and after stimulation. Our results demonstrate that a large number of genes exhibit divergent expression between B2 and B19 haplotype cells both prior and after stimulation. These differences in gene expression appear to be regulated by complex epigenetic mechanisms that need further investigation.

OBJECTIVE To evaluate the short- and long-term outcomes of dogs undergoing surgical ligation for a left-to-right shunting patent ductus arteriosus (PDA), identify risk factors for intraoperative hemorrhage and intra- and postoperative complications, and report overall mortality rates. ANIMALS 417 client-owned dogs undergoing surgical ligation for a left-to-right shunting PDA between January 2010 and January 2020. PROCEDURES Data recorded included patient signalment, echocardiogram findings, intraoperative complications and mortality, postoperative complications, and short- and long-term outcomes. RESULTS There was no association between age and risk of intraoperative hemorrhage (P = .7), weight and intraoperative hemorrhage (P = .96), or increasing left atrium-to-aortic (LA:Ao) ratio and intraoperative hemorrhage (P = .08). Intraoperative hemorrhage occurred in 10.8% of patients. Intraoperative mortality was 2%. Ninety-five percent of dogs experiencing intraoperative hemorrhage survived to discharge. Survival to discharge was 97%. One- and 5-year survival rates were 96.4% and 87%, respectively. CLINICAL RELEVANCE Surgical ligation for a left-to-right shunting PDA is recommended due to the good long-term prognosis. Certain preoperative factors such as age, weight, and the presence and degree of mitral valve regurgitation had no detectable association with risks of intraoperative hemorrhage and, therefore, should not preclude surgical treatment for a left-to-right shunting PDA. Future studies are needed to further assess the association between increasing LA:Ao ratio and risk of intraoperative hemorrhage.

Disease resistance and susceptibility has been associated with the major histocompatibility complex (MHC) in several species. This study aimed to better characterize the molecular basis for dramatically different nitric oxide production and associated immune function between the B2 and the B19 haplotype chicken macrophages in response to IFNγ stimulation, previously shown by our laboratory. A next generation RNA sequencing approach was employed to analyze gene expression from purified macrophages from each haplotype group (B2 vs. B19) across 9 time points spanning seven days. Ultimately, our data shows global dysregulation of gene expression in B19 haplotypes correlating with increased disease susceptibility of this haplotype. Our results demonstrate that transcription factors (TF) exhibit divergent expression between B2 and B19 haplotype cells both prior to and after stimulation. Our results also reveal that miRNAs exhibit divergent expression between B2 and B19 haplotype cells both, prior to, and after stimulation with IFNγ. In contrast to TFs, miRNAs can modulate gene product levels post-transcriptionally. We also identify ubiquitin-related enzymes and factors that exhibit divergent expression between B2 and B19 haplotype cells. Some of our results indicate that snoRNAs exhibit divergent expression between B2 and B19 haplotype cells, which is noteworthy because snoRNAs can modulate genes epigenetically. Taken together our results suggest that the global dysregulation of gene expression observed in B19 haplotypes can at least in part be attributed to differential epigenetic regulation.