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 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

. Recently an increasing pocket depth was found to be related to an increasing probing force. The purpose of the present study was to investigate whether or not a plateau value in pocket depth measurements exists and to study, with different probing forces, the location of the tip of the probe in relation to the periodontal fibers and the alveolar bone. Two groups of patients were selected for this study; in one group a number of teeth had to be extracted for periodontal reasons (the extraction group) and in the other a single periodontal surgical procedure was required (the surgery group). All patients received preliminary treatment consisting of plaque control and removal of subgingival deposits. At the time of the investigation the gingival condition was assessed by means of a new index, the Periodontal Pocket Bleeding Index (P.P.B.I.) The criteria were: 0 - no bleeding of the pocket after probing with a force of 0.75N, and 1 - bleeding of the pocket within 30 sec after probing with a force of 0.75N. After local anesthesia in the extraction group, reference marks parallel to the long axis of the experimental teeth were cut with a cylindrical diamond burr. By means of the pressure probe, pocket depth measurements were performed with increasing forces of 0.50, 0.75, 1.00 and 1.25N. After extraction and staining of the remnants of the periodontal fibers, the distance from the most coronal intact connective tissue fibers to the most apical point of the reference marks was measured. In the surgery group using the same pressure probe, interproximal measurements with increasing forces of 0.50, 0.75, 1.00 and 1.25N were made from the apical border of the restorations to the bottom of the pocket. The same measurement, this time to the crest of the alveolar bone, was repeated after a flap had been raised.

Results with the P.P.B.I. showed that oral hygiene procedures resulted in a mean index of 0.36 in the surgery group and 0.43 in the extraction group. The results of the present study indicated that 1) using a probe of 0.63 mm diameter, the optimal force level for clinical pocket depth measurements is 0.75N, 2) a force of 0.75N is clinically well tolerated and meets with few objections from patients, 3) when a probing force of 0.75N is used the tip of the probe in both shallow and deep periodontal pockets is located at the most coronal intact connective tissue fibers, 4) a plateau value in pocket depth measurements is found when a probing force of 1.25N is employed, and 5) the mean width of the connective tissue attachment is approximately 1.9 mm.

Probing force and the relationship of the probe tip to the periodontal tissues

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...

Philip A. Brewer

Papers

The Cytochemical staining and measurement of protein with mercuric bromphenol blue