<p>The Nature publication by Coale <em>et al.</em> examines UCYN-A, which evolved from a cyanobacterial species capable of converting N<sub>2</sub> into organic nitrogenous compounds, and its relationship with the marine alga <em>Braadurosphaera bigelowii</em>. It has already been established that UCYN-A and <em>B. bigelowii</em> have a symbiotic relationship, where <em>B. bigelowii</em> functions as a so-called host, and has taken up the UCYN-A bacteria into its cell in a process known as endosymbiosis. <strong>The symbiont, UCYN-A, fixes nitrogen for the host</strong> whereas <em>B. bigelowii</em> supplies organic carbon and a conducive living environment. This paper proved that UCYN-A is not simply a symbiont, but has instead evolved into an organelle for the eukaryotic alga for nitrogen fixation, and is now called the <strong>"nitroplast"</strong><ahref="#cite11"style="color: #185A4F;">[11]</a>.</p>
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<p>The discovery of the nitroplast captured our interest - we had considered a project on nitrogen fixation before but failed to see a way in which we could innovate or propose new solutions to the problems previous teams faced. All diazotrophs (bacteria and archaea that fix atmospheric N<sub>2</sub>) use the <strong>enzyme nitrogenase</strong> to fix nitrogen, but the expression of this enzyme presents great difficulties: it is <strong>irreversibly damaged by reacting with oxygen</strong>, while at the same time catalyzing an energetically demanding reaction. Due to this, diazotrophs have evolved very complex mechanisms to couple nitrogen fixation with respiration and/or photosynthesis, which so far has been beyond reach in terms of reproduction by synthetic biologists. The <strong>nitroplast solves this problem, acting as a fully contained compartment within a eukaryote where nitrogen fixation takes place</strong>, utilizing several years of evolutionary optimization.</p>
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