Project description:Comparison of social dominance phenotypes induced in the cichlid A. burtoni females with the goal of comparing to other gene expression profiles of social dominance Used platform GPL928 In many species, under varying ecological conditions, social interactions among individuals result in the formation dominance hierarchies. Despite general similarities, there are substantial differences across species, populations, environments, life stages, sexes, and individuals. Understanding the proximate mechanisms of this variation is an important step toward understanding the evolution of social behavior. However, physiological changes associated with dominance such as gonadal maturation and somatic growth, often complicate efforts to identify the specific underlying mechanisms. We demonstrate complementary analysis tools to allow a comparative approach to high-throughput expression profiling that allow us to both test a priori hypotheses and generate new hypotheses about the mechanisms and evolution of social dominance. Using experimental manipulation to produce female dominance hierarchies in the cichlid A. burtoni, heralded as a genomic model of social dominance, we generate gene lists, and assess molecular gene modules. We demonstrate a general pattern of “masculinization” of the female neural gene expression profile and compare expression biases between male and female dominance hierarchies. Using a threshold-free approach to identify correlation throughout gene ranked lists, we query previously published datasets from maternal behavior, alternative reproductive tactics, cooperative breeding and sex-role reversal to describe correlations among neural gene expression profiles. These complementary approaches capitalize on the high-throughput gene expression profiling from similar behavioral phenotypes in order to address the mechanism associated with social dominance behavioral phenotypes.
Project description:Social plasticity is a pervasive feature of animal behavior. Animals adjust the expression of their social behavior to the daily changes in social life and to transitions between life-history stages, and the ability to change in these ways impacts their Darwinian fitness. This behavioral plasticity may be achieved either by rewiring or by biochemically switching nodes of the neural network underlying the social behavior in response to perceived social information. Independent of the proximate mechanisms, at the neuromolecular level social plasticity relies on the regulation of gene expression, such that different neurogenomic states emerge in response to different social stimuli and the switches between states are orchestrated by signaling pathways that interface the social environment and the genotype. Here, we test this hypothesis by characterizing the changes in the brain profile of gene expression in response to social odors in the Mozambique Tilapia, Oreochromis mossambicus. This species has a rich repertoire of social behaviors during which both visual and chemical information are conveyed to conspecifics. Specifically, dominant males increase their urination frequency during agonist encounters and during courtship to convey chemical information reflecting their dominance status. We recorded electro-olfactograms to test the extent to which the olfactory epithelium can discriminate between olfactory information from dominant and subordinate males as well as from pre- and post-spawning females. We then performed a genome-scale gene expression analysis of the olfactory bulb and the olfactory cortex homolog in order to identify the neuromolecular systems involved in processing these social stimuli. Our results show that different olfactory stimuli from conspecificsM-bM-^@M-^Y have a major impact in the brain transcriptome, with different chemical social cues eliciting specific patterns of gene expression in the brain. These results confirm the role of rapid changes in gene expression in the brain as a genomic mechanism underlying behavioural plasticity and reinforce the idea of an extensive transcriptional plasticity of cichlid genomes, especially in response to rapid changes in their social environment. Brain samples from 40 African cichlid males, Oreochromis mossambicus were collected after stimulation with different social olfactory stimuli. Samples were collected from 2 brain areas: BO and Dp after males were exposed to dominant (DOM) and subordinate (SUB) male urine and pre- (PRE) and post-ovulatory (POST) female scent. In OB 5 replicates were collected from males exposed to DOM and 6 to the other stimuli. For Dp 5 replicates were collected from males exposed to DOM and POST, 4 to SUB and 6 to PRE.
Project description:Social plasticity is a pervasive feature of animal behavior. Animals adjust the expression of their social behavior to the daily changes in social life and to transitions between life-history stages, and the ability to change in these ways impacts their Darwinian fitness. This behavioral plasticity may be achieved either by rewiring or by biochemically switching nodes of the neural network underlying the social behavior in response to perceived social information. Independent of the proximate mechanisms, at the neuromolecular level social plasticity relies on the regulation of gene expression, such that different neurogenomic states emerge in response to different social stimuli and the switches between states are orchestrated by signaling pathways that interface the social environment and the genotype. Here, we test this hypothesis by characterizing the changes in the brain profile of gene expression in response to social odors in the Mozambique Tilapia, Oreochromis mossambicus. This species has a rich repertoire of social behaviors during which both visual and chemical information are conveyed to conspecifics. Specifically, dominant males increase their urination frequency during agonist encounters and during courtship to convey chemical information reflecting their dominance status. We recorded electro-olfactograms to test the extent to which the olfactory epithelium can discriminate between olfactory information from dominant and subordinate males as well as from pre- and post-spawning females. We then performed a genome-scale gene expression analysis of the olfactory bulb and the olfactory cortex homolog in order to identify the neuromolecular systems involved in processing these social stimuli. Our results show that different olfactory stimuli from conspecifics’ have a major impact in the brain transcriptome, with different chemical social cues eliciting specific patterns of gene expression in the brain. These results confirm the role of rapid changes in gene expression in the brain as a genomic mechanism underlying behavioural plasticity and reinforce the idea of an extensive transcriptional plasticity of cichlid genomes, especially in response to rapid changes in their social environment.
Project description:Among the adaptations of aquatic species during evolution of terrestrial tetrapods was the development of an epidermis preventing desiccation. In present day mammals, keratinocytes of the epidermis, using a membrane-bound transglutaminase (Tgm1), accomplish this function by synthesizing a scaffold of cross-linked protein to which a lipid envelope is attached. This study characterizes the abilities of two homologous transglutaminase isozymes in the teleost fish tilapia to form cross-linked protein structures and their expression in certain tissues. Results indicate they are capable of membrane localization and of generating cellular structures resistant to detergent solubilization. They are both expressed in epithelial cells of the lip, buccal cavity and tips of gill filaments. Adaptation of transglutaminase use in evolution of terrestrial keratinocytes evidently involved refinements in tissue expression, access to suitable substrate proteins and activation of cross-linking during terminal differentiation.
Project description:This experiment examined ovary gene expression differences between females in primitively eusocial Polistes metricus paper wasps. Specifically, we compared expression patterns between groups of females that differed in their reproductive dominance status. We compared dominant and subordinate foundresses, dominant and subordinate workers, and egg-laying queens. The purpose was to investigate how the social environment and dominance status affect ovary gene expression in individual females.
Project description:This experiment examined brain gene expression differences between females in primitively eusocial Polistes metricus paper wasps. Specifically, we compared expression patterns between groups of females that differed in their reproductive dominance status. We compared dominant and subordinate foundresses, dominant and subordinate workers, and egg-laying queens. The purpose was to investigate how the social environment and dominance status affect brain gene expression in individual females, and to compare these results to previous studies on dominance and aggression on other animals.
Project description:Social dominance encompasses winning dyadic contests and gaining priority access to resources and reproduction. Disposition to dominance is influenced by environmental factors, particularly during early postnatal life and adolescence. A disinhibitory mPFC microcircuit has been implicated in the expression of dominance in the “tube test” paradigm of social competition in mice, but the neuronal and transcriptional plasticity associated with the environment induced increase in social dominance is not known. We previously reported that male pups raised by physically active (as opposed to sedentary) dams exhibit dominance and increased reproductive fitness, and here we show that social isolation from weaning also increases dominance. By using these preweaning and postweaning environmental models, we tested if dominance is associated with transcriptional plasticity and a specific transcriptional profile in one or more cell types in the mPFC. Given that the mPFC is composed of several cell types, we used single cell transcriptomics to characterize the influence of the preweaning maternal and postweaning social environment on cell-type specific gene expression. The preweaning maternal effect, but not postweaning social isolation, caused gene expression changes in a wide range of cell types including pyramidal neurons, various interneurons, and astrocytes. However, both the maternal effect and social isolation induced the coordinated downregulation of synaptic channel, receptor, and adhesion genes in parvalbumin positive (PV) interneurons. This suggests an impaired PV interneuron-mediated inhibition of pyramidal cells in animals predisposed to dominance, a notion consistent with dominant behavior being driven by the disinhibition of mPFC pyramidal neurons.