Nuclear dualism is a characteristic feature of the ciliated protozoa. Tetrahymena have two different nuclei in each cell. The larger, polyploid, somatic macronucleus (MAC) is the site of transcriptional activity in the vegetatively growing cell. The smaller, diploid micronucleus (MIC) is transcriptionally inactive in vegetative cells, but is transcriptionally active in mating cells and responsible for the genetic continuity during sexual reproduction. Although the MICs and MACs develop from mitotic products of a common progenitor and reside in a common cytoplasm, they are different from one another in almost every respect.
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http://dx.doi.org/10.1016/B978-0-12-385967-9.00003-7 | DOI Listing |
Proc Natl Acad Sci U S A
September 2024
Max Planck Institute for Biology, Tübingen 72076, Germany.
Most eukaryotes have one nucleus and nuclear genome per cell. Ciliates have instead evolved distinct nuclei that coexist in each cell: a silent germline vs. transcriptionally active somatic nuclei.
View Article and Find Full Text PDFAntioxid Redox Signal
April 2024
Department of Physiology and Pharmacology "Vittorio Erspamer, " Sapienza University of Rome, Rome, Italy.
The nuclear factor erythroid 2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) system is a master regulator of redox homeostasis and cell adaptation to a variety of exogenous and endogenous stressors. Accumulating evidence from the last decade indicates that the impairment of the redox balance leads to oxidative stress (OS), a common alteration occurring in many human acute and chronic inflammatory diseases, such as cancer, diabetes, neurodegeneration, and metabolic disorders, and aging. Being located at the intersection of crucial signaling pathways, NRF2 can influence several cellular functions, which extend beyond the maintenance of the redox balance and include cellular metabolism, proteostasis, mitochondrial function and inflammation.
View Article and Find Full Text PDFGenome Res
January 2023
Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette Cedex, France.
With its nuclear dualism, the ciliate constitutes a unique model to study how host genomes cope with transposable elements (TEs). harbors two germline micronuclei (MICs) and a polyploid somatic macronucleus (MAC) that develops from one MIC at each sexual cycle. Throughout evolution, the MIC genome has been continuously colonized by TEs and related sequences that are removed from the somatic genome during MAC development.
View Article and Find Full Text PDFJ Eukaryot Microbiol
September 2022
Program in Organismic and Evolutionary Biology, University of Massachusetts Amherst, Amherst, Massachusetts, USA.
Ciliates are defined by the presence of dimorphic nuclei as they have both a somatic macronucleus and germline micronucleus within each individual cell. The size and structure of both germline micronuclei and somatic macronuclei vary tremendously among ciliates. Except just after conjugation (i.
View Article and Find Full Text PDFEur J Protistol
February 2022
Taller de Sistemática y Biogeografía, Facultad de Ciencias, Universidad Nacional Autónoma de México. Av. Universidad 3000, Circuito Exterior s/núm. Ciudad Universitaria, CP 04510, Coyoacán, Ciudad de México, Mexico.
Karyorelictids are a group of ciliates inhabiting marine and freshwater biotopes and possessing a non-dividing macronucleus. We describe a new freshwater species based on morphology and the 18S rRNA gene sequence data. Loxodes tziscaensis n.
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