Project description:Songbirds provide rich natural models for studying the relationships of brain anatomy, behavioral function, environmental signals and gene expression. Under the Songbird Neurogenomics Initiative, investigators from more than a dozen laboratories collected brain samples from six species of songbird under a range of experimental conditions, and 488 of these samples were analyzed systematically for gene expression by microarray. ANOVA was used to test 32 planned contrasts in the data, revealing the relative impact of different factors. The brain region from which tissue was taken had the greatest influence on gene expression profile, affecting the majority of signals measured by the 18,848 non-redundant cDNAs spotted on the microarray. Social and environmental manipulations had highly variable impact, ranging from nil in some cases to robust in others. Several specific genes were identified as points of interest in the evolution of mechanisms by which environmental signals influence behavior. The data were also analyzed using Weighted Gene Co-expression Network Analysis (WGCNA) followed by Gene Ontology (GO) analysis. This revealed modules of co-regulated genes that are also enriched for specific functional annotations such as M-bM-^@M-^\ribosomeM-bM-^@M-^] (expressed more highly in juvenile brain) and M-bM-^@M-^\dopamine metabolic processM-bM-^@M-^] (expressed more highly in striatal song control nucleus Area X). These results underscore the complexity of influences on neural gene expression and provide a resource for studying how these influences are integrated during natural experience. RNA samples were collected from six different songbird species (phylogeny in SI Appendix, Figure S1) and representing 80 different M-bM-^@M-^\treatmentsM-bM-^@M-^], i.e., combinations of species, brain region, sex, age, and behavioral state. The tissue samples were organized around 15 standalone experiments (Table 1 and SI Appendix, Table S1), contributed by investigators in a dozen different laboratories but analyzed under uniform conditions in a single laboratory as originally planned under the Songbird Neurogenomics Initiative. Each sample was hybridized to a zebra finch cDNA array along with a universal reference (a pool of zebra finch telencephalic RNA). e01: Brain regions HVC and RA were collected from Gambel's White crowned sparrows (Zonotrichia leucophrys gambelii) from the following experimental groups: long-term Short Day (SD); Long Day (LD) with Testosterone (T) for 3, 7, and 21 days (3LD+T, 7LD+T, 21LD+T respectively); SD and removal of T at 1 and 2 days (1SD-T, 2SD-T). Six biological replicates per group, five biological replicates in 3LD+T.HVC group. All samples were hybridized against the SoNG universal reference RNA pool.
Project description:The genome of the white-throated sparrow (Zonotrichia albicollis) contains an inversion polymorphism on chromosome 2 that is linked to predictable variation in a suite of phenotypic traits including plumage color, aggression, and parental behavior. Differences in gene expression between the two color morphs, which represent the two common inversion genotypes (ZAL2/ZAL2 and ZAL2/ZAL2m), are therefore of potential interest toward understanding the molecular underpinnings of these phenotypes. To identify genes that are differentially expressed between the two morphs and correlated with behavior, we quantified both behavior and gene expression in a population of free-living white-throated sparrows. We quantified behavioral responses to simulated territorial intrusions (STIs) early during the breeding season. In the same birds, we then performed a transcriptomewide analysis of gene expression in two behaviorally relevant brain regions, the medial amygdala and hypothalamus. Using network analyses, we identified modules of genes that were correlated with both morph and STI-induced singing behavior. The majority of these genes were located within the inversion, demonstrating the profound effect the inversion has on the expression of genes captured by the rearrangement. Gene pathway analyses revealed that in the medial amygdala, the most prominent pathways were those related to steroid hormone receptor activity. Within these pathways, the only gene encoding such a receptor was ESR1 (estrogen receptor alpha). Our results thus suggest that ESR1 and related genes are important for behavioral differences between the morphs.