Gata2 in Hematopoietic Cell Generation

The mammalian hematopoietic system is maintained by hematopoietic stem cells (HSC). Whereas in the adult, they reside in the bone marrow, the first HSCs are generated in the main vasculature of the midgestation embryo as a result of tightly regulated extrinsic and intrinsic molecular signals. Transcriptional regulation is pivotal to the establishment of HSC fate during development and the Gata2 transcription factor is central to this process. Genetic deletion of Gata2 shows that it is essential for the embryonic generation of HSCs, hematopoietic progenitor cells (HPC), and also for the establishment of some mature blood lineages, such as mast cells. Although previous studies with HPC/HSC enriched populations indicate the importance of Gata2 in their generation, there has been no direct way for studying Gata2-expressing cells in normal embryonic development, and in in vitro hematopoietic differentiation assays. In this thesis research, I use a novel Gata2Venus reporter embryonic stem cell (ESC) system and mouse model to dissect the role of Gata2 in hematopoietic differentiation and development. I show that Venus expression discriminates progressive stages of hematopoietic cell generation in vitro that are highly analogous to the in vivo waves of hematopoietic cell generation. My results demonstrate the involvement of the Gata2 downstream target, Gpr56 (a putative HSC regulator), in the development of HPCs, and reveal the redundant expression and function of Gpr56 with another G-protein coupled receptor, Gpr97. This redundancy may explain the previous contradictory data in the field regarding the requirement for Gpr56 in HSCs, and opens the way for new strategies to delineate the role of Gpr56 in HSC emergence. In addition to HSCs and HPCs, the mast cell lineage is one of the few mature blood cell types that expresses Gata2. Taking advantage of the Gata2Venus ESC reporter line and human induced pluripotent stem cell (iPSC) lines, I found a novel and powerful approach to rapidly generate mast cells for inflammation and allergy research applications. This thesis research has furthered our understanding of the role of Gata2 in in vivo embryonic development, and in in vitro pluripotent stem cell hematopoietic differentiation approaches, providing the basis for the development of future therapeutic strategies in blood and inflammation research

Identification of co-expression gene networks, regulatory genes and pathways for obesity based on adipose tissue RNA Sequencing in a porcine model

Background: Obesity is a complex metabolic condition in strong association with various diseases, like type 2 diabetes, resulting in major public health and economic implications. Obesity is the result of environmental and genetic factors and their interactions, including genome-wide genetic interactions. Identification of co-expressed and regulatory genes in RNA extracted from relevant tissues representing lean and obese individuals provides an entry point for the identification of genes and pathways of importance to the development of obesity. The pig, an omnivorous animal, is an excellent model for human obesity, offering the possibility to study in-depth organ-level transcriptomic regulations of obesity, unfeasible in humans. Our aim was to reveal adipose tissue co-expression networks, pathways and transcriptional regulations of obesity using RNA Sequencing based systems biology approaches in a porcine model. Methods: We selected 36 animals for RNA Sequencing from a previously created F2 pig population representing three extreme groups based on their predicted genetic risks for obesity. We applied Weighted Gene Co-expression Network Analysis (WGCNA) to detect clusters of highly co-expressed genes (modules). Additionally, regulator genes were detected using Lemon-Tree algorithms. Results: WGCNA revealed five modules which were strongly correlated with at least one obesity-related phenotype (correlations ranging from -0.54 to 0.72, P <0.001). Functional annotation identified pathways enlightening the association between obesity and other diseases, like osteoporosis (osteoclast differentiation, P = 1.4E(-7)), and immune-related complications (e. g. Natural killer cell mediated cytotoxity, P = 3.8E(-5); B cell receptor signaling pathway, P = 7.2E(-5)). Lemon-Tree identified three potential regulator genes, using confident scores, for the WGCNA module which was associated with osteoclast differentiation: CCR1, MSR1 and SI1 (probability scores respectively 95.30, 62.28, and 34.58). Moreover, detection of differentially connected genes identified various genes previously identified to be associated with obesity in humans and rodents, e.g. CSF1R and MARC2. Conclusions: To our knowledge, this is the first study to apply systems biology approaches using porcine adipose tissue RNA-Sequencing data in a genetically characterized porcine model for obesity. We revealed complex networks, pathways, candidate and regulatory genes related to obesity, confirming the complexity of obesity and its association with immune-related disorders and osteoporosis

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

RadioAstron gravitational redshift experiment: Status update

A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4 7 10−4. We expect to reach 2.5 7 10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission

RadioAstron gravitational redshift experiment: status update

A test of a cornerstone of general relativity, the gravitational redshift effect, is currently being conducted with the RadioAstron spacecraft, which is on a highly eccentric orbit around Earth. Using ground radio telescopes to record the spacecraft signal, synchronized to its ultra-stable on-board H-maser, we can probe the varying flow of time on board with unprecedented accuracy. The observations performed so far, currently being analyzed, have already allowed us to measure the effect with a relative accuracy of 4 × 10−4 . We expect to reach 2.5×10−5 with additional observations in 2016, an improvement of almost a magnitude over the 40-year old result of the GP-A mission.Astrodynamics & Space Mission