The structure and mode of division of the nucleus of budding yeast cells have been studied by phase-contrast microscopy during life and by ordinary microscopy after Helly fixation. The components of the nucleus were differentially stained by the Feulgen procedure, with Giemsa solution after hydrolysis, and with iron alum haematoxylin. New information was obtained in cells fixed in Helly's by directly staining them with 0.005% acid fuchsin in 1% acetic acid in water. Electron micrographs have been made of sections of cells that were first fixed with 3% glutaraldehyde, then divested of their walls with snail juice, and postfixed with osmium tetroxide. Light and electron microscopy have given concordant information about the organization of the yeast nucleus. A peripheral segment of the nucleus is occupied by relatively dense matter (the "peripheral cluster" of Mundkur) which is Feulgen negative. The greater part of the nucleus is filled with fine-grained Feulgen-positive matter of low density in which chromosomes could not be identified. Chromosomes become visible in this region under the light microscope at meiosis. In the chromatin lies a short fiber with strong affinity for acid fuchsin. The nucleus divides by elongation and constriction, and during this process the fiber becomes long and thin. Electron microscopy has resolved it into a bundle of dark-edged 150 to 180 A filaments which extends between "centriolar plaques" that are attached to the nuclear envelope.

https://rupress.org/jcb/article-pdf/29/1/129/1067979/129.pdf

A fiber apparatus in the nucleus of the yeast cell

SUMMARY: Treatment of the cells of various Bacillus spp. with an alkaline solution of sodium hypochlorite resulted in dissolution of the cells and liberation of the intracellular lipid inclusion bodies. Analyses of the isolated and purified inclusions of Bacillus cereus grown under a variety of cultural conditions showed them to contain about 89% poly-β-hydroxybutyrate and 11% ether-soluble lipid. Parallel estimations of the poly-β-hydroxybutyrate content of intact organisms by Lemoigne's chloroform extraction method showed that all of it was present in the lipid inclusions. These observations form the basis of a simple and rapid method of estimating the poly-β-hydroxybutyrate content of Bacillus spp. It consists essentially of digesting a washed bacterial suspension with a standard alkaline hypochlorite solution under standard conditions and measuring the residual turbidity.

The isolation and estimation of the poly-beta-hydroxybutyrate inclusions of Bacillus species.

SYNOPSIS. Seven species of limax amoebae were isolated into clonal, monoxenic cultures with Aerobacter aerogenes from material collected from freshwater habitats. Studies were made of their trophic structure, nuclear division, cyst structure, some aspects of cytochemistry, and other characteristics. Six new species are described: Vahlkampfia inornata, V. avara, V. jugosa, Hartmannella limacoides, H. vermiformis, and H. exundans. The well-known species Naegleria gruberi (Schardinger, 1899) is re-described on the basis of 8 strains; its flagellated phase was found to be biflagellate, with rare exceptions.



A correlation exists between the manner of locomotion and the pattern of nuclear division in the limax amoebae in the family Vahlkampfiidae and those in the genus Hartmannella.



Trophic amoebae of all species had a PAS-positive surface layer, altho results with H. vermiformis and H. exundans were less definite than with other species. All species except H. limacoides formed cysts in culture. The cyst walls of all cyst-forming species were strongly PAS-positive, but results of the zinc chloroiodide test for cellulose were negative with the method used.



The genus Hartmannella Alexeieff, 1912, is re-defined to include those species which assume a simple, monopodial limax-like form during locomotion and have nuclear division similar to that of metazoan cells and to distinguish it from the genus Acanthamoeba Volkonsky, 1931.

Taxonomic Criteria for Limax Amoebae, with Descriptions of 3 New Species of Hartmannella and 3 of Vahlkampfia*

Publisher Summary The nucleus is usually considered as playing a dual role in the cell. It is the carrier of genetic specificity and the organization center for cell function. Techniques of importance in the study of nucleoproteins include methods for determining the natural ultraviolet absorption of living and fixed cells and also the absorption in visible light of cells fixed and stained with acid or basic dyes and various cytochemical reactions. The photometric methods are applied to cells, including two recent symposia. Much of the modern quantitative cytology depends upon the validity of these techniques. Cytophotometric methods are simple in principle; and yet the possible sources of error are so numerous and difficult to estimate under practical measuring conditions that there are few adequate studies of the accuracy and reproducibility available. This chapter presents the tests devised to check the actual performance of measuring instruments. Obstacles, such as inhomogeneity, which has been estimated on theoretical grounds to give very large errors in measurements on nuclei, are discussed.

Quantitative Aspects of Nuclear Nucleoproteins

Publisher Summary The non-living organic matter in sea water is derived from a variety of plant sources, including phytoplankton, attached aquatic vegetation in shallow waters, macroscopic pelagic algae, and waterborne and windborne materials of terrestrial origin. The relative importance of these various sources cannot be stated precisely, but there is little doubt that phytoplankton is the most important source. Phytoplankton production, as determined by C14 fixation, falls within the range of 50-15Og of carbon per m2 in a year in the major ocean basins; however, some regions, notably the high arctic, are less productive than this and higher levels are attained in some coastal and estuarine waters and probably in oceanic areas of intense upwelling.

Particulate Organic Matter in Sea Water

1. The mercuric bromphenol blue reaction as used for development of protein spots on filter paper has been found to be applicable to the cytological staining of proteins.2. The optimum procedure is identical in detail with that described by Kunkel and Tiselius for filter paper spots, except that a neutral aqueous solution is substituteed for ammonia vapor in the final color development.3. The sharp and intense staining of protein permits good differentiation of structures often difficult to observe, such as cilia, spindle elements, regions of spindle fiber attachment to chromosomes and "lamp brush" chromosomes.4. The procedure is specific for proteins and those peptides which are not removed in the washing procedure.5. The preparations stained by this procedure follow the Beer and Lambert Laws in microspectrophotometric measurements. The absorption maximum is at 610 millimicrons.6. Basic proteins bind the dye under the conditions of the method even when Hg is omitted. Other proteins bind the dye by coupli...

The Cytochemical staining and measurement of protein with mercuric bromphenol blue

1. The capacity of nucleic acids to combine with basic dyes under various conditions was investigated by means of fixed tissues and model systems. Observations and experiments suggest that the specificity for nuclear DNA which methyl green exhibits in many, but not all, tissues is caused by blockage of stainable groups of ribonucleic acid by protein.2. Nuclear staining with methyl green is also subject to modification by changes in the degree of protein interference, and impairment of stainability cannot be correlated unequivocally with depolymerization of DNA.3. Since variable degrees of RNA staining, differences in the extent to which DNA staining is affected by protein interference, and possibly changes in the degree of polymerization of the DNA may all influence the staining intensity of nuclei, methyl green staining is not a very suitable method for quantitative determination of DNA in cell nuclei.

Studies on basophilia of nucleic acids: the methyl green stainability of nucleic acids

1. Quantitative changes in the staining capacity of nuclear DNA and basic proteins during pycnosis of guinea pig follicle cells were investigated by photometric techniques. The great density of these pycnotic nuclei requires special precautions during photometric analysis.2. The results show that amounts of measurable DNA, in terms of Feulgen dye, decrease during pycnosis, probably because of progressive nuclear fragmentation. At the same time the methyl green basophilia, per unit Feulgen-DNA, is greatly enhanced. Basic proteins show an even greater relative increase in their capacity to bind acid dye during pycnotic degeneration.3. These data are interpreted to indicate that a dissociation of the normal nucleoprotein complexes occurs during the degenerative process; this leads to unmasking of charged groups which had previously been unavailable for combination with dye ions.4. The pattern of pycnosis in the present material appears to differ from that previously described for tumor nuclei.

Max Alfert

Papers

The Cytochemical staining and measurement of protein with mercuric bromphenol blue

Studies on basophilia of nucleic acids: the methyl green stainability of nucleic acids

Changes in the staining capacity of nuclear components during cell degeneration