Several glycoproteins which inhibit the agglutinability of Saccharomyces cerevisiae mating type a cells were partially purified from extracts of mating type a cells. These proteins, called a-agglutinin, were labeled with 1251-Bolton-Hunter reagent. The labeled oi-agglutinin showed specific binding to a cells. Such specific binding approached saturation with respect to agglutinin or cells and was inhibited in the presence of excess unlabeled a-agglutinin. Nonspecific binding was similar in a and d cells, was neither saturable nor competable, and was three-to fourfold less than the specific binding to a cells at maximum tested agglutinin concentrations. The major a-specific binding species had a low electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels and had an apparent molecular weight of 155,000 by rate zonal centrifugation. Endo-N-acetylglucosaminidase H digestion of the purified glycoprotein complex converted the low-mobility material to four maijor and several minor bands which were resolved by polyacrylamide gel electrophoresis. All but two minor peptides bound specifically to a cells. Analyses of agglutinin from mnn mutants confirmed the deglycosylation results in suggesting that the N-linked carbohydrate portion of a-agglutinin was not necessary for activity. Gl (8,27), and a pronouhced change in cell morphology (3, 7).Sexual agglutination provides an excellent model system for the study of eucaryotic cell interactions and their regulation at the molecular level. The agglutination reaction has been characterized in yeasts of the genus Hansenula and found to be the result of the interaction of a pair of complementary glycoproteins, one from each mating type (5,23,24). More recently, similar molecules have been isolated from Saccharomyces kluyveri (18) and Saccharomyces cerevisiae (12, 17, 26, 28, 29, 31). These studies revealed certain common elements in sexual agglutination in yeasts. Ih each species except S. cerevisiae the agglutination molecule (agglutinin) from the cells corresponding to the a mating type has been fdund to be relatively heat stable and sensitive to reducing agents and to contain a higher proportion of carbohydrate than the corresponding molecule from the opposite mating type. By contrast, the agglutinin from mating types analogous to a cells is heat labile and stable to reducing agents and contains a smaller proportion of carbohydrate (4). Most of the studies of agglutinins in S. cerevisiae, however, have used autoclaving to solubilize the molecules. Therefore the reported a-agglutinin glycoprotein must be heat stable

GEMS-0067 (PI 643420) maize line is a homozygous mutant of the recessive amylose-extender (ae) allele and an unknown number of high-amylose modifier (HAM) gene(s). GEMS-0067 produces starch with a approximately 25% higher resistant-starch (RS) content than maize ae single-mutant starches. The objective of this study was to understand how the HAM gene(s) affected the RS content and other properties of ae-background starches. Nine maize samples, including G/G, G/F1, G/H, F1/G, F1/F1, F1/H, H/G, H/F1, and H/H with HAM gene-dosages of 100, 83.3, 66.7, 66.7, 50, 33.3, 33.3, 16.7, and 0%, respectively, were produced from self- and intercrosses of GEMS-0067 (G), H99ae (H), and GEMS-0067xH99ae (F1) in a generation-means analysis (GMA) study. RS contents of examined starches were 35.0, 29.5, 28.1, 32.0, 28.2, 29.4, 12.9, 18.4, and 15.7%, respectively, which were significantly correlated with HAM gene-dosage (r = 0.81, p < 0.01). Amylose content, number of elongated starch granules, and conclusion gelatinization temperature increased with the increase in HAM gene-dosage. X-ray diffraction study showed that the relative crystallinity (%) of starch granules decreased with the increase in HAM gene-dosage. The results suggested that the HAM gene-dosage was responsible for changes in starch molecular structure and organization of starch granules and, in turn, the RS formation in the maize ae mutant starch.

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Traditionally, high amylose starch (HAS) from maize (Zea mays L.) has been mainly used as an ingredient in gum candies and as an adhesive for corrugated cardboard. Two recent advances have increased interest in the use of HAS. The first one has been the development of starch-based biodegradable thermo plastics. Second, high amylose maize is a source of resistant starch (RS), a type of starch that resists digestion. As a food additive, consumers can benefit from added RS since it will lower the glycemic index and the risk of colon cancer in accordance with recent research in food science. Normal maize has about 25% amylose starch. A maize inbred line, GEMS-0067 (Reg. no GP-550, PI 643420) possesses high amylose modifier gene(s) that, together with the recessive amylose extender (ae) gene, raises the starch amylose percentage to at least 70%. The objective of this study was to determine the gene effects, nonallelic interactions and heritability of high amylose content in maize using Bogyo's triploid model. Nine populations were derived from a cross between H99ae, a maize inbred line with 55% amylose starch, and GEMS-0067. Data were collected from two locations in Missouri (MO) and South Dakota (SD) over 2 years (2005 and 2006). Incomplete dominance explained some of the inheritance of HAS. Maternal effects were also detected. The triploid models for MO and SD were separately established based on the corresponding data in 2005 and 2006. The additive and type 1 dominance effects in MO, and the additive, type 1 dominance, type 2 dominance, and additive 9 additive in SD were significantly different from zero meaning that those effects played an important role in amylose synthesis. Both broad-sense and narrowsense heritabilities were high indicating that high amylose content could be effectively selected for in a segregating population.

Binding of Saccharomyces cerevisiae alpha-agglutinin to target a cells was assayed by agglutination inhibition and 125I-alpha-agglutinin binding. The assays showed characteristics of equilibrium binding, namely saturability, competability, and the establishment of a kinetic endpoint in the presence of free alpha-agglutinin and free receptor. The binding was heterogeneous, displaying strong binding (10(9) liters/mol) and a weaker interaction. There were about 2 X 10(4) strong binding sites per a cell. Denaturing gels displayed identical labeled species binding to the a cells in the weak and strong interactions. Furthermore, weakly bound material could subsequently bind tightly to fresh a cells, implying that the same species of alpha-agglutinin was bound in the two states.