Neural Crest and Placodal Cells Contributions to Cranial Sensory Development

The sensory system of vertebrates is incredibly complex. Many important components of the sensory system are located within the cranial region, including the sense organs and cranial sensory ganglia. Early in development two progenitor populations, the neural crest and the cranial placodes, arise at the neural plate border and throughout vertebrate development contribute to the developing vertebrate peripheral sensory system. The interactions and contributions of both of these cell populations to the development of the pituitary system, the eyes, the nose, the ears, and the cranial ganglia of the head and neck are vital for the appropriate development of an embryo’s nervous system. In this dissertation we explore the contributions of both the neural crest and placodal cells to the sensory system of the developing embryo. In Chapter 1 we review the origin of these two cell populations at the neural plate border and give an overview of the development of the various cranial peripheral sensory systems and their placode and neural crest contributions. In Chapter 2 we use replication incompetent avian retroviruses to lineage trace both the olfactory placode and the neural crest to their respective cellular contributions in the olfactory system. We confirm previous studies which showed that GnRH neurons of the nose receive contributions from both the olfactory placode and the neural crest and we show that both the olfactory placode and the neural crest contribute to the olfactory neurons of the olfactory epithelium. However, neural crest alone gives rise to the olfactory ensheathing cells which are critical for neuronal migration from the olfactory epithelium to the forebrain. We also show for the first time that the neural crest gives rise to the p63 positive horizontal basal stem cell population of the olfactory epithelium. In Chapter 3, along with collaborators from SUNY Buffalo, we show that multipotent and functional NC cells can be derived by induction with a growth factor cocktail containing FGF2 and IGF1 from cultures of human inter-follicular keratinocytes (KC) isolated from elderly donors. They also maintained their multipotency, as evidenced by their ability to differentiate into all NC-specific lineages including neurons, Schwann cells, melanocytes, and smooth muscle cells (SMC). Notably, upon implantation into chick embryos, adult NC cells behaved similar to their embryonic counterparts, migrated along stereotypical pathways, and contributed to multiple NC derivatives in ovo. These results suggest that KC-derived NC cells may provide an easily accessible, autologous source of stem cells that can be used for treatment of neurodegenerative diseases or as a model system for studying disease pathophysiology and drug development. Finally, in Chapter 4 we discuss future directions and experiments that I plan to pursue post-graduation. I propose to conduct a closer examination of the variants of GnRH neurons across developmental time in various representative taxa of cartilaginous fish and reptiles. Furthermore, I intend to identify and experimentally confirm a molecular regulatory region for GnRH2, the most highly conserved variant across vertebrates, within the chicken embryo. Once this regulatory region is identified, the sequence can also be used to probe the genomes of other non-model taxa. Finally, I would like to perform lineage analysis using DiI in a non-model system to probe the embryonic origins (neural crest vs. placode) of the GnRH neurons in more ancient taxa.</p

Neural crest stem cells from human epidermis of aged donors maintain their multipotency in vitro and in vivo

Neural crest (NC) cells are multipotent stem cells that arise from the embryonic ectoderm, delaminate from the neural tube in early vertebrate development and migrate throughout the developing embryo, where they differentiate into various cell lineages. Here we show that multipotent and functional NC cells can be derived by induction with a growth factor cocktail containing FGF2 and IGF1 from cultures of human inter-follicular keratinocytes (KC) isolated from elderly donors. Adult NC cells exhibited longer doubling times as compared to neonatal NC cells, but showed limited signs of cellular senescence despite the advanced age of the donors and exhibited significantly younger epigenetic age as compared to KC. They also maintained their multipotency, as evidenced by their ability to differentiate into all NC-specific lineages including neurons, Schwann cells, melanocytes, and smooth muscle cells (SMC). Notably, upon implantation into chick embryos, adult NC cells behaved similar to their embryonic counterparts, migrated along stereotypical pathways and contributed to multiple NC derivatives in ovo. These results suggest that KC-derived NC cells may provide an easily accessible, autologous source of stem cells that can be used for treatment of neurodegenerative diseases or as a model system for studying disease pathophysiology and drug development

Harnessing the NEON data revolution to advance open environmental science with a diverse and data-capable community

It is a critical time to reflect on the National Ecological Observatory Network (NEON) science to date as well as envision what research can be done right now with NEON (and other) data and what training is needed to enable a diverse user community. NEON became fully operational in May 2019 and has pivoted from planning and construction to operation and maintenance. In this overview, the history of and foundational thinking around NEON are discussed. A framework of open science is described with a discussion of how NEON can be situated as part of a larger data constellation—across existing networks and different suites of ecological measurements and sensors. Next, a synthesis of early NEON science, based on >100 existing publications, funded proposal efforts, and emergent science at the very first NEON Science Summit (hosted by Earth Lab at the University of Colorado Boulder in October 2019) is provided. Key questions that the ecology community will address with NEON data in the next 10 yr are outlined, from understanding drivers of biodiversity across spatial and temporal scales to defining complex feedback mechanisms in human–environmental systems. Last, the essential elements needed to engage and support a diverse and inclusive NEON user community are highlighted: training resources and tools that are openly available, funding for broad community engagement initiatives, and a mechanism to share and advertise those opportunities. NEON users require both the skills to work with NEON data and the ecological or environmental science domain knowledge to understand and interpret them. This paper synthesizes early directions in the community’s use of NEON data, and opportunities for the next 10 yr of NEON operations in emergent science themes, open science best practices, education and training, and community building

Through Genera and Generations:A Systematic Study of Elasmobranch-hosted Cestodes of the Indo-Pacific, with Comments on Phylogenetic Relationships

Collection of new material from the bamboosharks Chiloscyllium indicum Gmelin, 1789 and Chiloscyllium hasseltii Bleeker, 1852 from Indonesian and Malaysian Borneo prompted reevaluation of the identity and host associations of the cestode genus Carpobothrium Shipley & Hornell, 1906. Light microscopical examination of whole mounts, histological sections, and egg preparations, in combination with scanning electron microscopy of scoleces, led to redescription of the type species Carpobothrium chiloscyllii Shipley and Hornell, 1906 from C. indicum, as well as description of a new species from C. hasseltii. Examination of some of Southwell’s material identified as C. chiloscyllii from the batoid hosts Urogymnus asperrimus Bloch & Schneider, 1801 and Rhynchobatus djeddensis Forsskål, 1775 in Sri Lanka, confirmed evidence from molecular work suggesting that these cestodes, which also bear pouch-like bothridia, represent a distinct group of cestodes from those parasitizing bamboosharks. Collection of new material from hosts Rhina ancylostoma Bloch & Schneider, 1801, Himantura uarnacoides Bleeker, 1852, and Himantura pastinacoides Bleeker, 1852 led to the formal erection of this novel batoid-hosted cestode genus as Orallobothrium n. gen. Light microscopical examination of whole mounts and scanning electron microscopy of scoleces resulted in the description of 3 novel species. Sequence data from the D1–D3 region of the 28S rDNA gene support recognition of the 3 species described here. The positions of both Carpobothrium and the new genus described here within the larger “tetraphyllidean” tree were found to be phylogenetically unstable across analyses. These and other differences in tree topology across analyses highlights the need for additional taxa and data to be applied to the problem if these relationships are ever to be fully elucidated

CRISPRi screens in human iPSC-derived astrocytes elucidate regulators of distinct inflammatory reactive states

Astrocytes become reactive in response to insults to the central nervous system by adopting context-specific cellular signatures and outputs, but a systematic understanding of the underlying molecular mechanisms is lacking. In this study, we developed CRISPR interference screening in human induced pluripotent stem cell-derived astrocytes coupled to single-cell transcriptomics to systematically interrogate cytokine-induced inflammatory astrocyte reactivity. We found that autocrine-paracrine IL-6 and interferon signaling downstream of canonical NF-κB activation drove two distinct inflammatory reactive signatures, one promoted by STAT3 and the other inhibited by STAT3. These signatures overlapped with those observed in other experimental contexts, including mouse models, and their markers were upregulated in human brains in Alzheimer's disease and hypoxic-ischemic encephalopathy. Furthermore, we validated that markers of these signatures were regulated by STAT3 in vivo using a mouse model of neuroinflammation. These results and the platform that we established have the potential to guide the development of therapeutics to selectively modulate different aspects of inflammatory astrocyte reactivity

NRG Oncology Updated International Consensus Atlas on Pelvic Lymph Node Volumes for Intact and Postoperative Prostate Cancer

PurposeIn 2009, the Radiation Therapy Oncology Group (RTOG) genitourinary members published a consensus atlas for contouring prostate pelvic nodal clinical target volumes (CTVs). Data have emerged further informing nodal recurrence patterns. The objective of this study is to provide an updated prostate pelvic nodal consensus atlas.Methods and materialsA literature review was performed abstracting data on nodal recurrence patterns. Data were presented to a panel of international experts, including radiation oncologists, radiologists, and urologists. After data review, participants contoured nodal CTVs on 3 cases: postoperative, intact node positive, and intact node negative. Radiation oncologist contours were analyzed qualitatively using count maps, which provided a visual assessment of controversial regions, and quantitatively analyzed using Sorensen-Dice similarity coefficients and Hausdorff distances compared with the 2009 RTOG atlas. Diagnostic radiologists generated a reference table outlining considerations for determining clinical node positivity.ResultsEighteen radiation oncologists' contours (54 CTVs) were included. Two urologists' volumes were examined in a separate analysis. The mean CTV for the postoperative case was 302 cm3, intact node positive case was 409 cm3, and intact node negative case was 342 cm3. Compared with the original RTOG consensus, the mean Sorensen-Dice similarity coefficient for the postoperative case was 0.63 (standard deviation [SD] 0.13), the intact node positive case was 0.68 (SD 0.13), and the intact node negative case was 0.66 (SD 0.18). The mean Hausdorff distance (in cm) for the postoperative case was 0.24 (SD 0.13), the intact node positive case was 0.23 (SD 0.09), and intact node negative case was 0.33 (SD 0.24). Four regions of CTV controversy were identified, and consensus for each of these areas was reached.ConclusionsDiscordance with the 2009 RTOG consensus atlas was seen in a group of experienced NRG Oncology and international genitourinary radiation oncologists. To address areas of variability and account for new data, an updated NRG Oncology consensus contour atlas was developed