Unique morphogenesis in Saccharomyces cerevisiae strain GS1731.

During the lag and early exponential phase of growth, 50-60% of budded cells of Saccharomyces cerevisiae strain GS1731 were multiply budded. During subsequent culture growth, the frequency of multiply budded cells decreased until by stationary phase multiply budded cells were rare. Data from renewed growth of a culture after hydroxyurea treatment indicated that GS1731 mother cells could assemble up to three pre-bud sites and begin bud growth and development in each. Light and scanning electron microscopy showed two or three very small buds emerging simultaneously on a mother cell and either reaching full size at the same time or enlarging sequentially. Immunofluorescence studies revealed that these multiply budded cells had multiple bundles of cytoplasmic microtubules. DAPI staining of nuclei revealed that some of the unbudded mother cells were multinucleate and completed cytokinesis giving rise to normal daughter cells.

The linear-plasmid-encoded toxin produced by the yeast Pichia acaciae: characterization and comparison with the toxin of Kluyveromyces lactis.

The toxin produced by Pichia acaciae was purified and its properties compared to those of the toxin from Kluyveromyces lactis. Like this toxin, the P. acaciae toxin is a protein comprised of three subunits (molecular masses 110, 39 and 38 kDa) with an associated chitinase activity and a pH optimum between 7.0 and 7.5. P. acaciae toxin also caused G1 cell cycle arrest. Of the thirteen recessive alleles that provided resistance in Saccharomyces cerevisiae to K. lactis toxin, only three also conferred resistance to P. acaciae toxin. Similarities and differences in the interactions of the two toxins with yeast cells are discussed.

Lipoprotein as a regulator of starch synthesizing enzyme activity.

Amylose precipitating factor, a lipoprotein, functions as a regulator of in vitro activity of glycogen/starch phosphorylase and of A/UDPglucose glucosyltransferase. The results suggest that this lipoprotein could act to stimulate the in vivo production by phosphorylase of long, linear glucans (amylose) from the short chain precursors. The lipoprotein also appears to switch A/UDPglucose glucosyltransferase from the elongation of branched glucan molecules (amylopectin and glycogen) to the elongation of linear glucans (amylose).

Effect of 2,4-dichlorophenoxyacetic acid on the structure and function of developing chloroplasts.

Dark-grown radish seedlings (Raphanus sativus L.) were sprayed with 10(-3) mol·l(-1) 2,4-dichlorophenoxyacetic acid and then were exposed to a 14:10 light: dark cycle. Cotyledon samples from these seedlings and unsprayed controls were taken for electron microscopy, chlorophyll determinations, and photosynthetic rate measurements at regular intervals for 72 h. A normal development of etioplasts to chloroplasts with formation of typical grana-fret work system was observed in the control cotyledons. The chloroplasts in the 2,4-D-treated cotyledons showed changes in the organization of the grana thylakoids; these thylakoids being more appressed to each other than in the controls. The chlorophyll content of treated plants was less than that of controls but the rate of chlorophyll biosynthesis was unaffected. The photosynthetic rate/mg chlorophyll was considerably higher for treated plants suggesting that 2,4-D treatment resulted in decreased size of the photosynthetic unit.

An ultrastructural survey of the genus Prototheca with special reference to plastids.

An ultrastructural investigation of six different species of Prototheca showed that all of them contained starch grains enclosed in double-membrane-bounded structures recognized as plastids. It is concluded that these unicellular species of Prototheca must be considered as non-photosynthetic algae.

Starch in Fungi: III. Isolation and Properties of an Amylose-precipitating Factor from Lentinellus Ursinus Fruit Bodies.

A factor which precipitates amylose has been isolated from Lentinellus ursinus (Fr.) Kühner fruit bodies. This factor could be a protein or a polypeptide. Glucose, maltose, and amylopectin do not affect the binding of amylose. Amylose binding is unaffected by temperature (4 to 40 C) or pH (6 to 8.5).

Molecular structure of starch-type polysaccharides from Hericium ramosum and Hericium coralloides.

Starch isolated from the fungi Hericium ramosum and Hericium coralloides differs from that of higher plants in that it consists only of short-chain amylose molecules (32 to 45 glucose units long).