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search.filters.applied.f.advisor: Goodisman, Michael × End date: 2016 × Start date: 2010 × search.filters.applied.f.isOrgUnitOfPublicationTitle: College of Sciences ×

Publication Search Results

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Aggressive Phenotypes in Malawi Cichlids Associated with V1AR Variant

2016-12 , Schappaugh, Nicholas A.

The cichlid model provides a great opportunity to explore diversity in behavioral phenotypes. Different groups of Malawi cichlids exhibit distinct patterns of behavior for a variety of scenarios, including aggressive encounters. These cichlids, characterized by the rocky or sandy habitats they occupy, exhibit strong genetic divergence, possessing large numbers of alternatively fixed variants between them. One such variant exists in the gene avpr1a, also known as V1aR, a major receptor for vasopressin in humans. This gene has been linked to behavioral effects across a variety of animal species, with this specific variant likely to have significant structural implications for the receptor product. Here we investigate the aggressive behaviors of a set of rock and sand hybrid fish for their association with the variant observed in V1aR. While specific metrics of aggression showed similar trends in these hybrids compared to those observed in the parental rock and sand species, ultimately these trends were not significant and were inconclusive. However, these results serve as a preliminary investigation of this gene’s involvement in cichlid aggressive behavior. In future work, further examination of the locus will be conducted utilizing more precise and powerful methods in order to draw stronger conclusions.

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A Study of the Relationship Between Bone Morphogenetic Proteins and Craniosynostosis

2015-06-30 , Whitton, Alaina

INTRODUCTION: The high prevalence for craniosynostosis (1) indicates the need for genetic understanding and identification of molecular pathways involved in the premature fusion of the skull sutures. Due to the existing knowledge about bone morphogenetic proteins (BMPs) on ectopic bone formation (2), the role of the BMP family in multiple types of craniosynostosis has long been hypothesized as a key player in the early onset of suture fusion. Based on this hypothesis, the genetic expression of six bone morphogenetic proteins were examined in the four types of synostosis. METHODS: Bone collected from patients undergoing corrective craniotomies at Children’s Healthcare of Atlanta were received and cells were grown from the bone fragments. From those cells, Real-time PCR was performed to determine the mRNA levels of the predetermined genes. RESULTS: Patients expressed individual results based on several factors including suture placement, age at surgery, sex, and predisposition to syndromes known to occur in conjunction with craniosynostosis. The BMPs that were involved in extraneous bone formation and osteoblast hyperactivity were found in high levels in the fused suture bone, while the mRNA levels of the inhibitors of bone formation such as NOG were decreased in fused sutures and exhibited high levels in the patent sutures. CONCLUSION: The study further elucidates the role of BMPs in the onset of craniosynostosis and offers insight to the molecular pathways involved.

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Epigenetics in social insects

2016-01-14 , Glastad, Karl M.

Virtually all multicellular organisms are capable of developing differently in response to environmental variation. At the molecular level, such developmental plasticity requires interpretation and perpetuation of environmental signals without changing the underlying genotype. Such non-genetic, heritable information is known as epigenetic information. This dissertation examines epigenetic information among social insects, and how differences in such information relate to phenotypic caste differences. The studies included herein primarily focus on one form of epigenetic information: DNA methylation. In particular, these studies explore DNA methylation as it relates to and impacts (i) alternative phenotype and particular gene expression differences in two social insect species, (ii) histone modifications, another important form of epigenetic information, in insect genomes, and (iii) molecular evolutionary rate of underlying actively transcribed gene sequences. We find that DNA methylation exhibits marked epigenetic and evolutionary associations, and is associated with alternative phenotype in multiple insect species. Thus, DNA methylation is emerging as one important epigenetic mediator of phenotypic plasticity in social insects.

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Molecular evolution in the social insects

2011-04-01 , Hunt, Brendan G.

Social insects are ecologically dominant because of their specialized, cooperative castes. Reproductive queens lay eggs, while workers take part in brood rearing, nest defense, and foraging. These cooperative castes are a prime example of phenotypic plasticity, whereby a single genetic code gives rise to variation in form and function based on environmental differences. Thus, social insects are well suited for studying mechanisms which give rise to and maintain phenotypic plasticity. At the molecular level, phenotypic plasticity coincides with the differential expression of genes. This dissertation examines the molecular evolution of genes with differential expression between discrete phenotypic or environmental contexts, represented chiefly by female queen and worker castes in social insects. The studies included herein examine evolution at three important levels of biological information: (i) gene expression, (ii) modifications to DNA in the form of methylation, and (iii) protein-coding sequence. From these analyses, a common theme has emerged: genes with differential expression among castes frequently exhibit signatures of relaxed selective constraint relative to ubiquitously expressed genes. Thus, genes associated with phenotypic plasticity paradoxically exhibit modest importance to overall fitness but exceptional evolutionary potential, as illustrated by the success of the social insects.

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Use of RNAi in Brachionus manjavacas to Inhibit Cold-Related Genes Implicated in Aging

2015-08-18 , Wilson, Julie

Aging can be affected by a number of factors, including temperature; for example, organisms tend to live significantly longer when exposed to colder temperatures. Previous studies suggest that this change in life expectancy due to temperature change has a genetic component. Through the use of RNA interference, we have found that aging genes can be knocked-down in our model animal, Brachionus manjavacas (Rotifera). Using RNAi, we examined the effect of genetic knock-down on genes related to life extension at lower temperatures (16oC) compared to standard culture temperatures (22oC). This study has provided evidence that temperature-dependent changes in longevity may be largely due to changes in expression levels in select genes: Forkhead Box C (FhBC), TRP7, and S6P. Future research may show that the life extending effects of certain living conditions may be obtainable through genetic treatment.

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