protosomen.
/ˈprəʊtəˌsəʊm/, U.S. /ˈproʊdəˌsoʊm/ 1. Genetics. The larger of two types of particle which together were postulated to constitute a gene. Cf. episome n. 1. Now historical.
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the world > life > biology > biological processes > genetic activity > genetic components > [noun] > gene > parts of gene
protosome1931
hot spot1958
homeobox1984
1931 D. H. Thompson in Genetics 16 268 The gene [is pictured] as consisting of a main particle firmly anchored in the chromosome with varying numbers of one or more kinds of other particles attached. The main particle is called the protosome and the attached particles the episomes.
1966 E. A. Carlson Gene xiii. 111 Using the position effect hypothesis with Thompson's protosome-episome chain theory of the gene, Dobzhansky tried to account for the various Bar mutations and their reversions.
2. Zoology. = prosoma n.
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the world > animals > invertebrates > bodies or parts > [noun] > anterior segment
prosoma1853
prosome1890
protosome1959
1959 Systematic Zool. 8 105/1 The essential differences in the nervous system of the compared groups..include also..the location of the brain in the protosome in Pogonophora.
1987 Deep-sea Res. A. 34 330 The animal's diameter [sc. an enteropneust] at the base of the protosome was 1 cm.
2000 Proc. National Acad. Sci. U.S.A. 97 4469/2 The three body parts [in enteropneusts] are the proboscis (protosome), collar (mesosome), and trunk (metasome).
This entry has been updated (OED Third Edition, September 2007; most recently modified version published online March 2022).
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n.1931