All articles starting with N

Nucleotide biosynthesis

Nucleotide biosynthesis, via de novo and salvage pathways, builds purine and pyrimidine nucleotides from PRPP, amino acids, CO2, and folate derivatives; regulated by CAD, MYC, and mTORC1 and targeted by antimetabolite drugs in cancer therapy.

Nucleotide catabolism

Nucleotide catabolism, also called nucleotide degradation, breaks down purine and pyrimidine nucleotides: purines to uric acid (gout, allopurinol target) and pyrimidines to beta-alanine and beta-aminoisobutyrate.

Nucleotide exchange factor Sil1, fungi

Fungal Sil1 (Sls1p, BAP), an ER nucleotide exchange factor for the Hsp70 chaperone BiP/Kar2p: armadillo-repeat clamp that releases ADP, reduces oxidized BiP, and whose loss in humans causes Marinesco-Sjögren syndrome.

Nucleotide excision repair

Nucleotide excision repair (NER), also called excision repair, is a conserved DNA repair pathway removing bulky helix-distorting lesions via dual incisions; sub-pathways GGR and TCR; defects cause xeroderma pigmentosum.

Sep 29, 2026

Nucleotide sequencing

Nucleotide sequencing determines the order of bases in DNA, spanning Sanger chain termination from 1977, massively parallel short reads from 2005, and long-read platforms like PacBio and Oxford Nanopore.

Nucleotide Transformer

The Nucleotide Transformer is a family of DNA language models by InstaDeep, NVIDIA, and Technical University of Munich, released in 2023 and published in Nature Methods in 2024.

Nucleotide-sugar transporter defects

Nucleotide-sugar transporter defects are rare congenital disorders of glycosylation in which SLC35 transporters fail to move sugars into the Golgi, causing disorders such as LAD II.

Nucleotidyltransferase-Associated Rossmannoid Fold

NARF (Nucleotidyltransferase-Associated Rossmannoid Fold, Pfam PF20299) is a predicted prokaryotic nucleotide-sensor domain related to receiver domains, always N-terminally fused to two transmembrane helices, found with SMODS and type III CRISPR systems.

Nuclera

Nuclera is a Cambridge, UK biotechnology company founded in 2013 as a University of Cambridge spinout, making the eProtein Discovery system for automated protein expression and purification.

Nucleus accumbens

Nucleus accumbens (NAc, NAcc), ventral striatum region with core, shell, and rostral pole subdivisions; GABAergic MSNs receiving VTA dopamine and prefrontal glutamate; central to reward, motivation, addiction relapse, and DBS targets.

Nucleus RTOS

Nucleus RTOS is a proprietary, royalty-free real-time operating system for embedded systems, first released as Nucleus PLUS in 1993 by Accelerated Technology, acquired by Mentor Graphics in 2002, and now sold by Siemens.

Nucleus sampling

Nucleus sampling, also called top-p sampling, is a language model decoding method that samples from the smallest set of top tokens whose probabilities sum to p.

Nucleus-Image

Nucleus-Image is a 17B-parameter open-source text-to-image diffusion model using a sparse mixture-of-experts architecture, released by NucleusAI on April 14, 2026 under Apache 2.0, activating roughly 2B parameters per generation.

Nucleus-independent chemical shift

Nucleus-independent chemical shift (NICS) is a computed magnetic criterion of aromaticity introduced by Paul von Ragué Schleyer and co-workers in 1996; negative values indicate aromaticity and positive values antiaromaticity.

Nuclide

A nuclide is a species of atom distinguished by its mass number, atomic number, and nuclear energy state, identifying specific nuclei like carbon-12 rather than a chemical element generally.

Nucor

Nucor Corporation is an American steelmaker headquartered in Charlotte, North Carolina. It pioneered the mini-mill model and makes roughly a quarter of all raw steel in the United States.

Nuctech

Nuctech, or 同方威视, is a Chinese security inspection manufacturer in Beijing, founded in 1997 as a Tsinghua University spin-off and a leading supplier of container X-ray scanners.

Nude (art)

The nude in art: the unclothed human body as an artistic genre, from Greek athletic ideals and Praxiteles' Knidian Aphrodite through the Renaissance revival, Kenneth Clark's naked/nude distinction, and feminist critique.

Nude beach

A nude beach, also called a clothing-optional or free beach, is a beach where users are at liberty to be nude, with etiquette centered on respect.

Nude Descending a Staircase, No. 2

Nude Descending a Staircase, No. 2 (Nu descendant un escalier n° 2) is Marcel Duchamp's 1912 oil painting of a figure in fragmented motion, rejected by Paris Cubists in 1912 and scandalizing the 1913 Armory Show; now in the Philadelphia Museum of Art.

nude mouse

The nude mouse is a hairless laboratory mouse with a Foxn1 mutation that leaves it without a thymus and mature T cells, widely used in cancer research.

Nude photography

Nude photography, also called artistic nude or figure photography, is a photographic genre depicting the unclothed human body, dating to 1839; distinct from erotica and from AI nudification imagery, it spans fine art, academic study, and consent-centered contemporary practice.

Nude recreation

Nude recreation, also called naturism or nudism, is non-sexual social nudity in leisure settings such as beaches, resorts, clubs, and saunas; defined by the INF in 1974, studied by Keon West for body-image and life-satisfaction benefits, and governed by intent-based indecent exposure laws.