THE DEVELOPMENT OF SEXUAL DIMORPHISM IN THE DROSOPHILA GONAD

Throughout the animal kingdom, sex-specific development is used to create different forms in males and females. Sexual dimorphism is important for successful reproduction both on social and biological levels, but is especially vital in the gonad, which must be sexually dimorphic so it can support germline differentiation into sperm and eggs. In Drosophila, adult testes and ovaries are highly specialized organs that can serve as good models for studying sex-specific gonadogenesis, however, it is not well understood how sexual dimorphism is initially established in the embryo. In this thesis I present an analysis of how differences between the male and female somatic gonad are brought about during early development. I have observed that the Drosophila gonad is already sexually dimorphic at the time of its initial formation, and have characterized two sex-specific cell types termed the male-specific somatic gonadal precursors (msSGPs) and the pigment cell precursors. msSGPs and pigment cells give rise to specific adult testis cell types and express Sox100B, a homolog of Sox9, a factor required for mammalian sex determination. These two cell types employ different cellular mechanisms, such as apoptosis and cell-cell signaling, to ensure sexual dimorphism in the gonad. Sex-specific gonad development relies on positional information provided by the homeotic genes and proper sexual identity downstream of the sex determination gene doublesex. The sexually dimorphic behavior of msSGPs and pigment cells appears to be controlled non-autonomously, which is distinct from cell-autonomous sex determination that has been reported for most other Drosophila somatic tissues. Finally, I have analyzed the function of Sox100B in gonad development, and have found a role in adult iii testis formation, suggesting that there is a conserved molecular mechanism for regulating sexual dimorphism between flies and mammals. These results demonstrate many common features between Drosophila and mammalian gonadogenesis. Thus, despite vast differences in initial sex determination between species, these data strongly support a hypothesis that the downstream regulation of sexual dimorphism in the gonad is an evolutionarily conserved process at the cellular and molecular levels

Temporal Transcriptional Profiling of Somatic and Germ Cells Reveals Biased Lineage Priming of Sexual Fate in the Fetal Mouse Gonad

The divergence of distinct cell populations from multipotent progenitors is poorly understood, particularly in vivo. The gonad is an ideal place to study this process, because it originates as a bipotential primordium where multiple distinct lineages acquire sex-specific fates as the organ differentiates as a testis or an ovary. To gain a more detailed understanding of the process of gonadal differentiation at the level of the individual cell populations, we conducted microarrays on sorted cells from XX and XY mouse gonads at three time points spanning the period when the gonadal cells transition from sexually undifferentiated progenitors to their respective sex-specific fates. We analyzed supporting cells, interstitial/stromal cells, germ cells, and endothelial cells. This work identified genes specifically depleted and enriched in each lineage as it underwent sex-specific differentiation. We determined that the sexually undifferentiated germ cell and supporting cell progenitors showed lineage priming. We found that germ cell progenitors were primed with a bias toward the male fate. In contrast, supporting cells were primed with a female bias, indicative of the robust repression program involved in the commitment to XY supporting cell fate. This study provides a molecular explanation reconciling the female default and balanced models of sex determination and represents a rich resource for the field. More importantly, it yields new insights into the mechanisms by which different cell types in a single organ adopt their respective fates

31st Annual Meeting and Associated Programs of the Society for Immunotherapy of Cancer (SITC 2016) : part two

Background The immunological escape of tumors represents one of the main ob- stacles to the treatment of malignancies. The blockade of PD-1 or CTLA-4 receptors represented a milestone in the history of immunotherapy. However, immune checkpoint inhibitors seem to be effective in specific cohorts of patients. It has been proposed that their efficacy relies on the presence of an immunological response. Thus, we hypothesized that disruption of the PD-L1/PD-1 axis would synergize with our oncolytic vaccine platform PeptiCRAd. Methods We used murine B16OVA in vivo tumor models and flow cytometry analysis to investigate the immunological background. Results First, we found that high-burden B16OVA tumors were refractory to combination immunotherapy. However, with a more aggressive schedule, tumors with a lower burden were more susceptible to the combination of PeptiCRAd and PD-L1 blockade. The therapy signifi- cantly increased the median survival of mice (Fig. 7). Interestingly, the reduced growth of contralaterally injected B16F10 cells sug- gested the presence of a long lasting immunological memory also against non-targeted antigens. Concerning the functional state of tumor infiltrating lymphocytes (TILs), we found that all the immune therapies would enhance the percentage of activated (PD-1pos TIM- 3neg) T lymphocytes and reduce the amount of exhausted (PD-1pos TIM-3pos) cells compared to placebo. As expected, we found that PeptiCRAd monotherapy could increase the number of antigen spe- cific CD8+ T cells compared to other treatments. However, only the combination with PD-L1 blockade could significantly increase the ra- tio between activated and exhausted pentamer positive cells (p= 0.0058), suggesting that by disrupting the PD-1/PD-L1 axis we could decrease the amount of dysfunctional antigen specific T cells. We ob- served that the anatomical location deeply influenced the state of CD4+ and CD8+ T lymphocytes. In fact, TIM-3 expression was in- creased by 2 fold on TILs compared to splenic and lymphoid T cells. In the CD8+ compartment, the expression of PD-1 on the surface seemed to be restricted to the tumor micro-environment, while CD4 + T cells had a high expression of PD-1 also in lymphoid organs. Interestingly, we found that the levels of PD-1 were significantly higher on CD8+ T cells than on CD4+ T cells into the tumor micro- environment (p < 0.0001). Conclusions In conclusion, we demonstrated that the efficacy of immune check- point inhibitors might be strongly enhanced by their combination with cancer vaccines. PeptiCRAd was able to increase the number of antigen-specific T cells and PD-L1 blockade prevented their exhaus- tion, resulting in long-lasting immunological memory and increased median survival

THE DEVELOPMENT OF SEXUAL DIMORPHISM IN THE DROSOPHILA GONAD

Throughout the animal kingdom, sex-specific development is used to create different forms in males and females. Sexual dimorphism is important for successful reproduction both on social and biological levels, but is especially vital in the gonad, which must be sexually dimorphic so it can support germline differentiation into sperm and eggs. In Drosophila, adult testes and ovaries are highly specialized organs that can serve as good models for studying sex-specific gonadogenesis, however, it is not well understood how sexual dimorphism is initially established in the embryo. In this thesis I present an analysis of how differences between the male and female somatic gonad are brought about during early development. I have observed that the Drosophila gonad is already sexually dimorphic at the time of its initial formation, and have characterized two sex-specific cell types termed the male-specific somatic gonadal precursors (msSGPs) and the pigment cell precursors. msSGPs and pigment cells give rise to specific adult testis cell types and express Sox100B, a homolog of Sox9, a factor required for mammalian sex determination. These two cell types employ different cellular mechanisms, such as apoptosis and cell-cell signaling, to ensure sexual dimorphism in the gonad. Sex-specific gonad development relies on positional information provided by the homeotic genes and proper sexual identity downstream of the sex determination gene doublesex. The sexually dimorphic behavior of msSGPs and pigment cells appears to be controlled non-autonomously, which is distinct from cell-autonomous sex determination that has been reported for most other Drosophila somatic tissues. Finally, I have analyzed the function of Sox100B in gonad development, and have found a role in adult iii testis formation, suggesting that there is a conserved molecular mechanism for regulating sexual dimorphism between flies and mammals. These results demonstrate many common features between Drosophila and mammalian gonadogenesis. Thus, despite vast differences in initial sex determination between species, these data strongly support a hypothesis that the downstream regulation of sexual dimorphism in the gonad is an evolutionarily conserved process at the cellular and molecular levels

Putting Impact First: Community-University Partnerships to Advance Authentic Neighborhood Sustainability

This article profiles a partnership between the Living Cully ecodistrict and Portland State University’s Sustainable Neighborhoods Initiative. The case studies presented in this article explore how Living Cully leveraged PSU assets to advance their goals, highlighting successes and lessons learned. This article also addresses how the partnership was formed, what makes the partnership innovative, the role of interdisciplinary/intercommunity organizational strategies, and how the community partner commits to urban sustainability and social justice

Vascular-mesenchymal cross-talk through Vegf and Pdgf drives organ patterning

The initiation of de novo testis cord organization in the fetal gonad is poorly understood. Endothelial cell migration into XY gonads initiates testis morphogenesis. However, neither the signals that regulate vascularization of the gonad nor the mechanisms through which vessels affect tissue morphogenesis are known. Here, we show that Vegf signaling is required for gonad vascularization and cord morphogenesis. We establish that interstitial cells express Vegfa and respond, by proliferation, to endothelial migration. In the absence of vasculature, four-dimensional imaging of whole organs revealed that interstitial proliferation is reduced and prevents formation of wedge-like structures that partition the gonad into cord-forming domains. Antagonizing vessel maturation also reduced proliferation. However, proliferation of mesenchymal cells was rescued by the addition of PDGF-BB. These results suggest a pathway that integrates initiation of vascular development and testis cord morphogenesis, and lead to a model in which undifferentiated mesenchyme recruits blood vessels, proliferates in response, and performs a primary function in the morphogenesis and patterning of the developing organ