The Genetic Control of Nucleolar Composition

Abstract

In a sense the study of the nucleolus occupies a key position in the analysis of the inter-relations of the nucleus and the cytoplasm. It is a structure within the nucleus, resembling the cytoplasmic structures in the type of nucleic acid it contains; at the same time, like other genetic effects, it is related to a definite locus in the chromosomes. Moreover, as has already been discussed in the previous paper, its function appears somehow to be connected with the synthetic activities of the cytoplasm. This being the case, the effects of genetic changes in the nucleolar regions upon the composition of the nucleolus should give some insight into the possible uses of this structure for the analysis of the problems associated with the action of the genes. Viewed from another aspect, changes in the composi- VOL. 26, 1940 515

Histochemical Studies of Nucleolus and Nucleolar Extrusions in Dipteran Oogenesis

“…It discharges the RNA and shows the presence of DNA in the five species studied (Schultz 1940, Yao 1949, Painter and Taylor 1942, Brachet 1950, 1957, Sharma 1966, 1967.…”

“…In the polytrophic ovaries, the nucleolar extrusions have been studied with light microscopy (Schultz et al 1940, Yao 1949, Hsu 1953, Sirlin 1959, Zalokar 1959, Krainsaka 1961, Bier 1963, Anderson and Lyford 1965, Sharma 1966, 1967. Important contributions to the subject of nucleolar extrusions in polytrophic ovaries have also been made with electron microscopy (King et al 1956, King 1960, 1964.…”

Nucleolus and Chromosomes in <i>Euglena gracilis</i>

“…The nucleolonema is believed to become organized independent of any chromosomal locus (50, 51, 133); the nucleolar organizer is a chromosomal region very likely with multiple genetic loci (10,78,112,127,131,148,150 . At mitosis the nucleolonema would fragment during prophase, after which each nucleolonemal segment would join a chromatid by its side; nucleolonemal segments would coalesce to reconstitute the nucleolus at telophase (50, 51, 64, 158).…”

A symposium on the structure of protoplasm / edited by William Seifriz.

“…Calvm, Kodani, and Goldschmidt (1940) consider that salivary gland chromosomes are essentially of the same structure as mammalian egg "lampbrush" chromosomes from which they consider chromatin is being sloughed off. Caspersson and Schultz (1940) , however, point out that the high concentration of ribonucleic acid in the cytoplasm occurs before the nuclear membrane breaks down. They observe that the cytoplasm or nucleolus which does not ordinarily stain with Feulgen does contain nucleic acids which must be assumed to be of the ribose type.…”