Define nucleoids

• Article • • 23 August 2019 Cell morphology and nucleoid dynamics in dividing Deinococcus radiodurans • • • • ORCID: orcid.org/0000-0003-1038-9681 • ORCID: orcid.org/0000-0001-5648-5295 • ORCID: orcid.org/0000-0002-1862-7712 • … • ORCID: orcid.org/0000-0002-9066-9095 Show authors Nature Communications volume 10, Article number: 3815 ( 2019) Our knowledge of bacterial nucleoids originates mostly from studies of rod- or crescent-shaped bacteria. Here we reveal that Deinococcus radiodurans, a relatively large spherical bacterium with a multipartite genome, constitutes a valuable system for the study of the nucleoid in cocci. Using advanced microscopy, we show that D. radiodurans undergoes coordinated morphological changes at both the cellular and nucleoid level as it progresses through its cell cycle. The nucleoid is highly condensed, but also surprisingly dynamic, adopting multiple configurations and presenting an unusual arrangement in which oriC loci are radially distributed around clustered ter sites maintained at the cell centre. Single-particle tracking and fluorescence recovery after photobleaching studies of the histone-like HU protein suggest that its loose binding to DNA may contribute to this remarkable plasticity. These findings demonstrate that nucleoid organization is complex and tightly coupled to cell cycle progression in this organism. In all organisms, genomic DNA is compacted several orders of magnitude and yet must remain accessible for essential DNA-rela...

The nucleoid (meaning nucleus-like) is an irregularly shaped region within the cell of a prokaryote that contains all or most of the genetic material, called genophore.[1] In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane. The genome of prokaryotic organisms generally is a circular, double-stranded piece of DNA, of which multiple copies may exist at any time. The length of a genome widely varies, but generally is at least a few million base pairs. As in all cellular organisms, length of the DNA molecules of bacterial and archaeal chromosomes is very large compared to the dimensions of the cell, and the genomic DNA molecules must be compacted to fit

Take a moment and look at yourself. How many organisms do you see? Your first thought might be that there's just one: yourself. However, if you were to look closer, at the surface of your skin or inside your digestive tract, you would see that there are actually many organisms living there. That’s right - you are home to around 100 trillion bacterial cells! All cells fall into one of these two broad categories. Only the single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes— pro means before and kary means nucleus. Animals, plants, fungi, and protists are all eukaryotes— eu means true—and are made up of eukaryotic cells. Often, though—as in the case of we humans—there are some prokaryotic friends hanging around. Despite these similarities, prokaryotes and eukaryotes differ in a number of important ways. A prokaryote is a simple, single-celled organism that lacks a nucleus and membrane-bound organelles. We’ll talk more about the nucleus and organelles in the next article on eukaryotic cells, but the main thing to keep in mind for now is that prokaryotic cells are not divided up on the inside by membrane walls, but consist instead of a single open space. The majority of prokaryotic DNA \text DNA start text, D, N, A, end text is found in a central region of the cell called the nucleoid, and it typically consists of a single large loop called a circular chromosome. The nucleoid and some other frequently seen features of prokaryotes are shown ...

The Nucleoid The nucleoid (meaning nucleus-like) is an irregularly-shaped region within the cell of a prokaryote that contains all or most of the genetic material. In contrast to the nucleus of a eukaryotic cell, it is not surrounded by a nuclear membrane. The genome of prokaryotic organisms generally is a circular, double-stranded piece of DNA, of which multiple copies may exist at any time. The length of a genome varies widely, but is generally at least a few million base pairs. Figure: Prokaryote cell nucleoid: Prokaryote cell (right) showing the nucleoid in comparison to a eukaryotic cell (left) showing the nucleus. The nucleoid can be clearly visualized on an electron micrograph at high magnification, where it is clearly visible against the cytosol. Sometimes even strands of what is thought to be DNA are visible. The nucleoid can also be seen under a light microscope.by staining it with the Feulgen stain, which specifically stains DNA. The DNA-intercalating stains DAPI and ethidium bromide are widely used for fluorescence microscopy of nucleoids. Experimental evidence suggests that the nucleoid is largely composed of about 60% DNA, plus a small amount of RNA and protein. The latter two constituents are likely to be mainly messenger RNA and the transcription factor proteins found regulating the bacterial genome. Proteins helping to maintain the supercoiled structure of the nucleic acid are known as nucleoid proteins or nucleoid-associated proteins, and are distinct fro...

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