Scott A. Juntti - US grants

Throughout the animal kindgdom, territorial and reproductive behaviors are often innate, indicating that their underlying neural substrates are genetically hardwired. Among vertebrates, many of these behaviors are controlled by the steroid hormone testosterone and its metabolites. Exposure of developing and adult brains to testosterone results in the masculinization of behavior, and in males of most species testosterone (or a metabolite) is necessary for the elicitation of mating and aggressive behavior as adults. The production of gonadal steroids such as testosterone is controlled by neurons of the hypothalamus expressing the neuropeptide gonadotropin releasing hormone (GnRH1). Some of these neurons project to the pituitary, where they control the release of the gonadotropins luteinizing hormone and follicle stimulating hormone into the bloodstream. These hormones bind receptors in the testes, stimulating the production of testosterone. Another subset of GnRH1 neurons project elsewhere in the brain, but the functional relevance of these neurons has not been tested. GnRH1 neurons exhibit dynamic cellular, electrophysiological, and gene transcription correlates of reproductive and territorial behaviors, making them candidate neurons to regulate behavioral outputs. To manipulate GnRH1 neurons, I will transgenically modify a cichlid fish, Astatotilapia burtoni, to express nitroreductase specifically in these cells, enabling their ablation in a temporally controlled manner. Experiments utilizing these fish in this proposal will directly test the function of GnRH1 neurons for behavior in transgenic adult A. burtoni. Further, comparison of the behavioral effects of hormone manipulation to GnRH1 neuron ablation will reveal the relative contributions of GnRH1 neurons to reproductive and territorial behavior via hormone synthesis versus direct connections to the neural circuits that generate these behaviors. This transgenic animal model in which GnRH1 neurons can be conditionally ablated in adult fish will provide a system to understand how these neurons contribute to behavior, and may provide insight into their regulation of fertility, puberty, and menopause.

This award is supported by the Major Research Instrumentation and the Chemistry Research Instrumentation programs. Professor Peter Nemes from the University of Maryland College Park and colleagues Daniel Falvey, Lyle Isaacs, Lisa Taneyhill and Scott Juntti are acquiring a high-resolution, high-pressure liquid chromatograph mass spectrometer with electrospray ionization capabilities (HR-HPLC-ESI-MS). In general, mass spectrometry (MS) is one of the key analytical methods used to identify and characterize small quantities of chemical species embedded in complex samples. In a typical experiment, the components flow into a mass spectrometer where they are ionized into ions and the ions' masses are measured. This highly sensitive technique allows the structure of molecules in complex mixtures to be studied. An instrument with a liquid chromatograph can separate mixtures of compounds before they reach the mass spectrometer. In the electrospray technique a high voltage is applied to a liquid to create an aerosol. This voltage is useful to produce ions from large molecules by avoiding the propensity of macromolecules to fragment when ionized. The acquisition strengthens the research infrastructure at the University and regional area. The instrument broadens participation by involving diverse groups of students in research and research training using this modern analytical technique. The acquisition also provides training opportunities to many undergraduate and graduate students as well as postdoctoral fellows at this institution. The new capability to measure both small biological and organic molecules in a shared Mass Spectrometry Facility has a broad impact on scientists and students in the District of Columbia-Maryland-Virginia region through workshops as well as curriculum modernization and collaborations with Bowie State University.


The award of the mass spectrometer is aimed at enhancing research and education at all levels. It especially impacts studies of metabolic effectors of embryonic development and hormone metabolite activity in nervous system functions. The instrumentation is also used for research on mitochondrial metabolism in the liver as well as molecular mechanisms in neural crest and dental placode cells. In addition, the MS provides information useful for the search of the next generation enzymatic kinetic isotope effects and for studying binders for the valosine-containing protein (VCP) that segregate protein molecules from large cellular structures. The mass spectrometer is also used to inform the design of efficient syntheses for molecular guest compounds. It is also utilized in investigations of electrophilic nitrogen containing species and their reactivity with proteins and nucleic acids.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

The genomic revolution has ushered in a new era of biological research. Genomes have been sequenced for not only humans and traditional laboratory animal models such as mice and fruit flies, but thousands of diverse organisms. However, to turn this data into a deep understanding of how genes function, scientists need the ability to manipulate these genes in the newly sequenced species. Recent years have seen dramatic technological improvements to genome editing in several of these species, enabling direct tests. An NSF-funded symposium at the Society for Integrative Biology (SICB) in Austin, TX in January 2023 will shine a spotlight on research in diverse species to reveal new principles of biological function. Work presented aims to accelerate development of these tools in additional species by gathering gene editing experts to teach their methods to others. Using tools like CRISPR/Cas9 gene editing, speakers have modified the genomes of species from jellyfish to mammals and many species in between. Studying many of the unique model organisms represented at SICB may have broad impacts including transformative knowledge advances, an understanding of ecologically important species, or medical insights. This symposium will help democratize gene editing tools to many species and advance knowledge of fundamental biological principles. <br/><br/>The advent of genetic manipulations has enabled incredible insights into genetic mechanisms that control biological processes. However, it has also promoted the consolidation of research into a limited number of species (eg, fruit fly, mouse, zebrafish, C. elegans). As a result, the genetic regulation of a tremendous variety of evolutionary adaptations across species have been understudied at a mechanistic level. The development of CRISPR/Cas genome editing, in particular, enables an expansion of the number of species in which genetic experiments can be performed. Some progress has been made in using gene-edited species to understand organismal biology in ways inaccessible with traditional model organisms. The goal of this symposium is to catalyze the transfer of knowledge and skills from researchers who have applied these technologies in new model organisms to scientists who would like to bring these approaches to their own research programs. A symposium at the 2023 Society for Integrative and Comparative Biology (SICB) conference, which will feature talks, discussions, and a workshop. The speakers (who span institution types, locations, genders, along a spectrum of career stages) have modified species from jellyfish to mammals and many species in between. There will also be an educational event in which speakers from the symposium provide small-group consultations plus a panel discussion. To disseminate this work, all speakers have agreed to publish data presented at SICB in Integrative and Comparative Biology.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.