Some notes on the problem of uncertainty in biological measurements

Problems of measurement and instrumentation in biolog

A window in time for the first evolutionary radiation

The window in time between the last globally sterilizing event and the evidence for a complex procaryotic ecosystem is quite narrow, perhaps as small as 200 million years. We will present a heuristic model outlining the first evolutionary radiation that could have led from primordial vesicles to the universal ancestor. The concept of the universal ancestor will be developed in terms of contemporary molecular biology

Prosecuting Nazi War Criminals In the United States: The Time in Which to Punish Them is Running Out

The purpose of this Note is to demonstrate that the United States can and must assert jurisdiction over Nazi war criminals in order to punish them properly

The Works of Stefan George

This translation of all the poems in the main body of the work of George extensively revises the first publication of "The Works of Stefan George" which appeared in 1949. The editors have also expanded the volume, adding a number of George's early poems under the collective title "Drawings in Grey", two essays (including the eulogy on Hölderin), and the lyrical drama "The Lady's Praying" along with a commentary by the translators

Modulation of Epigenetic Mark 5-hydroxymethylcytosine in Intestinal Organoid Cultures

Chromatin regulation plays a role in establishing and maintaining cell identity, and is generally highly dynamic between stem and differentiated cells. The intestinal epithelium is a monolayer of cells that is replaced every 3-5 days, and is thus a rapidly self-renewing and differentiating tissue. It is not currently understood how the integrity of the intestinal stem cell (ISC) genome is maintained or how the identity of a differentiated cell is dictated. Vital to chromatin regulation and gene expression are epigenetic modifications, such as methylation. The addition of methyl groups to the nucleotide cytosine silences genes, while demethylation allows gene expression. Demethylation pathways produce the epigenetic mark 5-hydroxymethylcytosine (5-hmC) as an intermediate. The conversion of 5-methylcytosine (5mC) to 5-hmC is accomplished by ten-eleven translocation (TET) enzymes, which require co-factors, such as the micronutrient alpha-ketoglutarate (a key intermediate in the Krebs cycle). Assessing the global 5-hmC abundance among distinct cellular populations will elucidate this epigenetic mark’s role in determination of cell fate. To investigate this aim, murine intestinal organoid cultures were exposed to varying dosages of dimethyl 2-oxoglutarate, a cell permeable form of alpha-ketoglutarate, in order to modulate TET activity and thus 5-hmC abundance. Through dot blot analysis of 5-hmC abundance, the ability to modulate the epigenetic mark was assessed. Results indicate that exposure of intestinal organoids to dimethyl 2-oxoglutarate leads to phenotypic differences compared to controls, but these differences cannot be attributed to 5-hmC abundance. Understanding the differences in 5-hmC across cellular populations will provide insight into the role of epigenetic modifications in regulating gene expression. Furthermore, the impact of micronutrients on the genome emphasizes the significance of cellular environment for cellular identity.Bachelor of Scienc