Project description:The Masai giraffe has experienced a population decline from 70,000 to 35,000 in the past three decades and was declared an endangered subspecies by the IUCN in 2019. The remaining number of Masai giraffe are geographically separated by the steep cliffs of the Gregory Rift escarpments (GRE) in Tanzania and Kenya dividing them into two populations, one west and one east of the GRE. The cliffs of the GRE are formidable barriers to east-west dispersal and gene flow and the few remaining natural corridors through the GRE are occupied by human settlements. To assess the impact of the GRE on Masai giraffe gene flow, we examined whole genome sequences of nuclear and mitochondrial DNA (mtDNA) variation in populations located east (Tarangire ecosystem) and west (Serengeti ecosystem) of the GRE in northern Tanzania. Evidence from mtDNA variation, which measures female-mediated gene flow, suggests that females have not migrated across the GRE between populations in the Serengeti and Tarangire ecosystems in the past ~289,000 years. The analysis of nuclear DNA variation compared to mtDNA DNA variation suggests that male-mediated gene flow across the GRE has occurred more recently but stopped a few thousand years ago. Our findings show that Masai giraffes are split into two populations and fulfill the criteria for designation as distinct evolutionary significant units (ESUs), which we denote as western Masai giraffe and eastern Masai giraffe. While establishing giraffe dispersal corridors across the GRE is impractical, conservation efforts should be focused on maintaining connectivity among populations within each of these two populations. The importance of these efforts is heightened by our finding that the inbreeding coefficients are high in some of these Masai giraffe populations, which could result in inbreeding depression in the small and fragmented populations.
Project description:Transcriptional profiling of cotton fiber cells from two cotton germplasm lines, MD 52ne and MD 90ne. Comparison of fiber cell transcription profiles is between the two germplasm lines and over a developmental time-course from 8 to 24 days post anthesis in four day intervals.
Project description:To evaluate the differential potential affected by SMARCE1 -MD/MD(R42A) , we performed RNA-sequencing (RNA-seq) of Smarce1-MD and control Smarce1-MD (R42A) embrynoic body.
Project description:Dating of wood is a major task in historical research, archaeology and paleoclimatology. Currently, the most important dating techniques are dendrochronology and radiocarbon dating. Our approach is based on molecular decay over time under specific preservation conditions. In the models presented here, construction wood, cold soft waterlogged wood and wood from living trees are combined. Under these conditions, molecular decay as a usable clock for dating purposes takes place with comparable speed. Preservation conditions apart from those presented here are not covered by the model and cannot currently be dated with this method. For example, samples preserved in a clay matrix seem not to fit into the model. Other restrictions are discussed in the paper. One model presented covers 7,500 years with a root mean square error (RMSE) of 682 years for a single measurement. Another model reduced to the time period of the last 800 years results in a RMSE of 92 years. As multiple measurements can be performed on a single object, the total error for the whole object will be even lower.
Project description:To evaluate the effects of mitotic degradation of SMARCE1 upon gene expression, we performed RNA-sequencing (RNA-seq) of cultures of four independent subclones each of Smarce1-MD and control Smarce1-MD (R42A) mESCs. We found that transcription of the core pluripotency regulatory network was not disrupted. In contrast, GO analysis showed that neural differentiation-associated terms were enriched among genes upregulated in Smarce1-MD mESCs. To better understand the difference in neural fates in the neural induction experiments, we performed differential gene expression analysis and gene set enrichment analysis (GSEA) studies. Mitotic degradation of SMARCE1 resulted in higher expression of GABA receptors and hyper-activation of synaptic signaling on neural induction, indicating the aberrant neural cell fate commitment compared to SMARCE1-MD (R42A) cultures. And then we add back BMP4 to partically rescue the phenotype and very small amount of BMP4 will rescue the phenotype.