Vacuoles in the Nucleoli ofZea MaysRoot Apices and their Possible Significance in Nucleolar Physiology

Nucleolar vacuolation in soybean root meristematic cells during recovery after chilling

“…Both higher activity of pre-ribosome synthesis and their transport during recovery, and migration of the granular component accumulated during plant chilling seem to prove that nucleolar vacuoles arise rather owing to pre-ribosomal particle migration from nucleolus to cytoplasm than to their synthesis in nucleolus. The results of the present studies support the opinion of many authors that the appearance of nucleolar vacuoles is related to rRNA transport from nucleolus to cytoplasm (Barlow 1970, De Barsy et al 1974, Deltour and De Barsy 1985, Olszewska et al 1985, Jennane et al 2000.…”

“…At early stage of Zea mays germination in root cells the appearance of vacuoles was correlated with the beginning of uridine incorporation into nucleoli (De Barsy et al 1974). In turn, Barlow (1970) did not agree that vacuolation level of nucleoli could be related to the activity of RNA precursor incorporation in different Zea mays root tip regions. Also in artichoke slices in natural conditions the nucleolar vacuoles formed when nucleolar RNA metabolism was slowed down (Rose et al 1972).…”

“…Decrease in nucleolar volume and nucleolar vacuole number as well as nucleolar activity in aging and in weaken tobacco cultured cells were observed (Johnson and Jones 1967). However, in Zea mays root tip cells the number of vacuoles in a nucleolus was inversely related to the nucleolar volume -appearance of nucleolar vacuoles resulted in nucleoli diminution, the smaller nucleoli correlated with the highest vacuolation which in turn depended on the activity of RNA production in a nucleolus (Barlow 1970, De Barsy et al 1974). On the contrary, in the case of nucleoli of soybean subjected to low temperature the nucleolar volume increased significantly and vacuolation level decreased drastically in comparison to the control nucleoli.…”

Polarized light and phase‐contrast studies of stained and unstained plant cell nucleoli

“…It has been observed by Barlow (1970) that nucleolar vacuoles in 2. mays root meristems are not stained by Azure-B. This observation lends support to the observations described here, namely that several standard staining procedures, including Azure-B, show no apparent effect on the optical properties of vacuolelike and other intranucleolar material when compared with the optical properties of unstained preparations.…”

The effect of physiological activation on nuclear morphology in Allium cepa.

“…As the R nucleoli that ac counted for 95% of the T0 nucleoli decreased in number, the Ov, EO and DB nucle oli increased. Because of these observations, the increase in nucleolar sizes, and vacuolation of nucleoli that enlarged, we infer that transcriptional activity was occurring in the NOR and that ribosomal subunits were accumulating around the nucleolus while others were being transported into the nucleoplasm and cytoplasm (Barlow 1970, DeBarsy et al 1974, Fransolet et al 1979, Galan-Cano et al 1975, Johnson 1969, Moreno-Diaz de la Espina et al 1980. Although area means for nucleoli within each of the four types were statistically alike (except for R nucleoli at TO and T3), we interpret the data to be biologically significant and infer that the sequence of nucleolar changes were as follows: R nucleoli enlarge to form Ov; Ov nucleoli undergo NOR extension to form E0; and, E0 nucleoli increase in size forming DB.…”