macronucleus


Also found in: Medical, Encyclopedia, Wikipedia.
Related to macronucleus: oral groove

mac·ro·nu·cle·us

 (măk′rō-no͞o′klē-əs, -nyo͞o′-)
n. pl. mac·ro·nu·cle·i (-klē-ī′)
The larger of two nuclei present in ciliate protozoans, which controls nonreproductive functions of the cell, such as metabolism.

mac′ro·nu′cle·ar adj.

macronucleus

(ˌmækrəʊˈnjuːklɪəs)
n, pl -clei (-klɪˌaɪ)
(Microbiology) the larger of the two nuclei in ciliated protozoans. Compare micronucleus

mac•ro•nu•cle•us

(ˌmæk roʊˈnu kli əs, -ˈnyu-)

n.
the larger of the two types of nuclei in ciliate protozoans, functioning in cell metabolism. Compare micronucleus.
[1890–95]
mac`ro•nu′cle•ar, adj.
References in periodicals archive ?
The main features used in the identification of ciliates were: body shape, position and number of contractile vacuoles, oral and somatic ciliatures, position of macronucleus and shape of inclusions and color and the cytoplasm.
A certain amount of DNA sequences found in the somatic macronucleus has to be eliminated during sexual reproduction, and PIWI proteins are known to play a major role in DNA elimination.
Cytoskeletal proteins perhaps evolved even earlier, in the common ancestor of bacteria, archaea and eukarya, but FtsZ in particular is considerate an ancient protein, because FtsZ and MreB (which is a protein found in bacteria and identified as a homologue of actin) (Koumandou, Wickstead, Ginger, van der Glezen, Dacks and Field, 2013; Wickstead and Gull, 2011; Cox, Foster, Hirt, Harris and Embley, 2008), and it has seen that even ciliates contain actin, although ciliates are microbial eukaryotes with two types of nuclei: a germline micronucleus (MIC) and a somatic macronucleus (MAC) (Faguy, Doolittle, 1998).
All species of ciliates harbor two different kinds of nuclei; micronucleus that is required for sexual reproduction and other one is transcriptionally active macronucleus (Baroin-Tourancheau et al., 1992; Forney and Rodkey, 1992; Budin and Philippe, 1998; Katz, 2001; Rautian and Potekhin, 2002; Garnier et al., 2004; Shin, 2005; Zufall et al., 2006; Nekrasova et al., 2010).
They had numerous, long cilia, macronucleus, and vacuoles, measured 70.54 [+ or -] 11.14 pm, and there was no apparent damage or host response.
Unidentified ciliates were recorded in gills, characterized by a big macronucleus and several micronuclei, with dense ciliature (Fig.
The macronucleus is spherical or occasionally elipsoidal, lies on the dorsal side and is located near the middle of the cell.
The micronucleus functions in mitosis and meiosis, whereas the macronucleus maintains routine cell function.
It has macronucleus at the posterior part of the body.
It gives rise to a workaday version of itself, a macronucleus, with just the animal's 27,000 or so genes and not the 95 percent of DNA that scientists typically call junk because it doesn't encode any proteins.
Ciliocytophthoria usually demonstrate cilia predominantly along one edge, but if viewed on end they may appear to be circumferentially ciliated.[1] Balantidium coli are uniformly covered with cilia.[21,22] Although dyssynchronous cilial motility was seen in this case, ciliocyiophthoria have also been noted to produce rhythmic motility.[23] Finally, ciliocytophthoria are anucleate (Figures 1 through 3), whereas B coli have a macronucleus that is typically indented or kidney shaped (Figure 4).[21,22] A careful inspection for these features should allow for accurate morphologic differentiation between ciliocytophthoria and B coli.
Ciliates possess two or more dimorphic nuclei: an active somatic macronucleus and a transcriptionally inert germline micronucleus.