Absence Of Yeast Research Articles

Protein-protein interactions of yeast DNA polymerase III with mammalian and yeast proliferating cell nuclear antigen (PCNA)/cyclin

We have previously reported the purification of yeast analogs to mammalian DNA polymerase δ and proliferating-cell nuclear antigen (PCNA)/cyclin: DNA polymerase III and yeast PCNA, respectively. Through the use of gel-filtration chromatography, we have studied the interaction of the model template-primer system poly(dA) · (dT) 16 (40:1) with yeast DNA polymerase III and with PCNAs. Yeast DNA polymerase III binds to the DNA in the absence of yeast PCNA/cyclin, but comigration of either yeast or calf thymus PCNA/cyclin with the DNA requires the additional presence of yeast DNA polymerase III. We could also isolate a DNA-calf thymus DNA polymerase δ-calf thymus PCNA/cyclin complex. From these data, we propose that PCNA/cyclin is involved not in the binding step of the polymerase to the template-primer, but in the elongation step. The 3′ → 5′ exonuclease associated with yeast DNA polymerase III acts in a distributive manner on poly(dA) · (pT) 16, and dissociates from the DNA when addition of dTTP allows switching from the exonuclease to the polymerase mode. Addition of PCNA/cyclin had no effect on these activities.

Yeast-Contaminated Nectar and its Effects on Bee Foraging

SummaryYeasts occur naturally in floral nectar and have been considered to be an influence on the foraging behaviour of bees. When honeybees were presented with a choice of flowers of milkweed, Asclepias syriaca, which were contaminated with yeasts in the nectar vs. yeast-free flowers, they showed no discrimination in visits or movements between the flower types. They moved to the closest flower (reward) regardless of the presence or absence of yeasts. The same results were obtained with the use of yeast-free and yeast-contaminated droplets of sugar syrup.

Simultaneous saccharification and fermentation of cellulose: effect of β- d-glucosidase activity and ethanol inhibition of cellulases

Compared with saccharification in the absence of yeast, simultaneous saccharification and fermentation (SSF) using Trichoderma cellulases and Saccharomyces cerevisiae enhanced cellulose hydrolysis rates by 13–30%. The optimum temperature for SSF was 35°C. The requirement for β- d-glucosidase (β- d-glucoside glucohydrolase, EC 3.2.1.21) in SSF was lower than for saccharification: maximal ethanol production was attained when the ratio of the activity of β- d-glucosidase to filter paper activity was ∼1.0. Ethanol inhibited cellulases uncompetitively, with an inhibition constant of 30.5 gl −1, but its effect was less severe than that of an equivalent concentration of cellobiose or glucose. No irreversible denaturation of cellulases [1,4-(1,3;1,4)-β- d-glucan 4-glucanohydrolase, EC 3.2.1.4] by ethanol was observed .

The Absence of Yeasts in Nectars of Selected Arizona Plants Attractive to Honey Bees, Apis mellifera1,2,3,4

Nectar samples were examined from blooms of saguaro cactus and 5 Citrus cultivars. Samples were streaked on plates of malt extract-yeast extract agar with glucose (YM medium), incubated, and examined for microbial growth. No yeasts were isolated from any nectar samples. Some possible explanations are discussed with respect to the absence of yeasts in the intestines of adult worker honey bees.

ZYMOMONAS AND ACETALDEHYDE LEVELS IN BEER

High acetaldehyde levels in beers during processing were found to be due to infection with Zymomonas anaerobia. Acetaldehyde only appeared in the absence of yeast and the level was correlated with the concentration of Z. anaerobia as determined by the time taken to produce hydrogen sulphide in a primed beer forcing test.

Developmental Physiology of Cestodes. V. Effects of Vitamin Deficient Diets and Host Coprophagy Prevention on Development of Hymenolepis diminuta

Effects of B vitamin deficient diets on Hymenolepis diminuta were studied. The worms were markedly affected by a diet deficient in all B vitamins only when host coprophagy was prevented, but some effects were noted in worms from hosts where coprophagy was allowed. Very few worms could establish themselves in coprophagy-prevented rats on the B vitamin deficient diet, and growth in weight, length, and proglottid numbers, and proglottid differentiation were severely impaired. Further investigation showed that the dietary absence of pyridoxine was responsible for the foregoing effects. Pyridoxine deficient worms exhibited abnormalities similar to those found in B vitamin deficient worms. The abnormalities were partially mitigated when rats were injected with 10 ,ug pyridoxine HCl/day while being fed pyridoxine deficient diets. The average size of the worms under these conditions was about half that of controls. However, if 10 jig pyridoxine HCl/day was provided in the diet, or if larger amounts of pyridoxine HC1 were injected, worm size was equal to controls. The results imply that vitamin B6 may be a growth factor for H. diminuta, and the worms may obtain the vitamin from the exocrino-enteric circulation when it is absent from the ingesta. Little is known about the vitamin requirements of any cestode, although the requirements of H. diminuta have received the most attention. Hager (1941) observed, over a period of several months, that a diet deficient in thiamine had no effect on the egg production of H. diminuta, but a diet deficient in all B vitamins, supplemented with thiamine, greatly decreased the egg production. These experiments were repeated by Chandler (1943) and Addis and Chandler (1944) except that they noted the effects on numbers of worms recovered and the total length of the worms in 14-, 28-, and 30-day infections. They reported that diets deficient in thiamine, or diets deficient in vitamins A, D, and E, supplemented with thiamine, stunted the worms, but only in female rats. Addis and Chandler (1946) later found that the dietary presence of none of the B vitamins (niacin, pyridoxine, pantothenic acid, riboflavin, biotin, p-aminobenzoic acid, inositol, choline, and folic acid), either collectively or individually, would support normal growth in the worms. They concluded that some factor (s) in yeast, other than the vitamins they included, was * This investigation was supported by Grants AI-06153 and 5 TOI AI-226 from the NIH, U. S. Public Health Service. t Present address: The Rockefeller University, New York, New York 10021. Received for publication 2 May 1969. necessary for normal growth and establishment of H. diminuta because their complete diet had contained yeast as the B vitamin source. Subsequently, Beck (1951) reported that "B vitamin deficient diets" decreased egg production in H. diminuta both in male and female rats. The rats on the "B vitamin deficient diet" received choline, thiamine, riboflavin, pyridoxine, calcium pantothenate, and p-aminobenzoic acid each day in excess of the daily requirement. Whether the vitamins were given by mouth or by injection was not stated. Under the conditions used by the foregoing investigators, H. diminuta did not require vitamins A, D, E, or thiamine in the host diet; however, the situation with respect to the other B vitamins was equivocal since dried brewer's yeast was included in their diets as the complete B vitamin source. Hence, elimination of B vitamins from the host diet was accompanied by a major dietary change since brewer's yeast comprised about 9% of the diet. Although the full implications of such a dietary change on H. diminuta have not been investigated, the data of Addis and Chandler (1946) indicated that the absence of yeast, replaced by the available B vitamins, resulted in a 52% reduction in length of the worms. The absence of synthetic vitamins from the yeast-free diet had no consistent effects on growth of H. diminuta when compared to the correct control diet, i.e., one in which

Comparative studies with Tribolium (Coleoptera, Tenebrionidae)—I: Productivity of T. castaneum (Herbst) and T. confusum Duv. on several commercially-available diets

Productivity (measured as the number of adult progeny produced in a given interval by a number of females) and relative developmental rates (the number of adult progeny found at specific intervals) have been determined for T. castaneum and T. confusum on a variety of different media. The media tested were flours of corn (C), rice (R), soy (S), whole wheat (W), a mixture of corn, rice, soy and whole wheat flour (M), white wheat (WW) and brown rice (BR) with and without a supplement of brewer's yeast. In T. confusum the ranking of productivity on these seven media was found to be M>W>C>BR>R>WW>S in both unsupplemented and yeast-supplemented media, but the performance on all media was somewhat increased by the addition of yeast. The order of productivity on these media with T. castaneum was similar to that obtained for T. confusum, except that the response to yeast supplements was much more pronounced for all media except soy. In particular, white wheat, brown rice and rice, which must be considered “poor” media for T. castaneum in the absence of yeast, compared very favorably, in terms of productivity, with whole wheat and corn when these media were supplemented with yeast. These data are summarized in Table 6 and Fig. 1. These productivity results are supported by information obtained about the developmental rates of the two species on these media-in general, developmental rate was much slower on those media showing the lowest productivity. From considerations of the content of the flours used, the data suggest that soy is more toxic to T. castaneum than to T. confusum, and that T. castaneum requires more vitamins and/or minerals than does T. confusum. This conclusion is largely judged by the performance of the two species on white and brown rice, and their performance on yeastless and yeast-supplemented media. The data are given in Table 5 and shown in graph form in Fig. 2. It is suggested that T. castaneum may require greater amounts of leucine, alanine, and aspartic acid than T. confusum, and that T. confusum requires larger amounts of threonine, tyrosine and possibly methionine than T. castaneum.

Novel action of potassium on a yeast and a counteraction by aluminium.

A PAPER1 from this laboratory described an improved method for the estimation of Oospora lactis Fres. (formerly known as Oidium lactis) in pressed bakers' yeast, using a medium consisting of ammonium succinate, mineral salts and agar. The method worked well with most yeasts, but one strain (Saccharomyces cerevisiae D.C.L. 557) prevented the growth of visible colonies of Oospora on the above medium. This effect has been further studied, and it has been found that the immediate cause of the inhibition was the presence in the medium of 2 × 10−2 M potassium (as the dihydrogen phosphate). This was demonstrated by excluding potassium from the medium, adding the phosphate as the sodium or ammonium salt. The mould then developed into dense colonies; these were not, however, quite so large as those grown on normal medium (containing potassium) in the absence of yeast. This reduction in size was due to the fact that Oospora required 3 × 10−4 M potassium ions for optimal growth on ammonium succinate, mineral salts, agar medium. When Yeast 557 was present, however, this concentration of potassium, added as sulphate or chloride to the medium (containing sodium or ammonium dihydrogen phosphate), inhibited the growth of the mould. The inhibition was largely overcome by the addition of 5 × 10−4 M aluminium (as ammonium alum) to the normal medium.

Joint action of a dextrinogenic amylase, a glucose-producing amylase and transglucosidase upon starch in the presence or absence of yeast

Curves of fermentable sugar production in the secondary phase of starch hydrolysis with joint systems of a crystalline dextrinogenic amylase, a highly purified glucose-producing amylase, and a partially purified transglucosidase, in the presence and absence of yeast, were observed. In the absence of yeast, the higher the ratio of dextrinogenic amylase to glucose-producing amylase, the more maltose was formed and more marked was the effect of the action of transglucosidase. In the presence of yeast, the effect of transglucosidase in decreasing the rate of secondary conversion was not observed, and a renewed rather rapid hydrolysis of the residual substrate took place. This fact was concluded, according to Pan et al., to be a result of the reconversion of presynthesized unfermentable oligosaccharides into fermentable sugars by the reversible action of transglucosidase after the removal of maltose by yeast. Further, it was concluded that the amount of glucose-producing amylase determines the rate of secondary fermentation and that the dextrinogenic amylase is indispensable as a complement of glucose-producing amylase although its activity need not be high unless a high concentration of viscous starch is used as the substrate.

各種糸状菌のアミラーゼに関する研究

1. Comparative studies were carried out on fermentable sugar production in secondary phase of starch hydrolysis with six mold enzyme solution (mold bran extracts of Aspergillus oryzae, Asp. usamii, Asp. awamori, Rhizopus tonkinensis, and α-amylase added extracts of Asp. usamii and Rhiz. tonkinensis), in the presence and absence of yeast. 2. It was concluded that the initial velocity of glucose formation from starch, referred here as “Glucose-Direct” activity(8) (G. D.) represents the amount of saccharogenic amylase (Table 1). 3. Generally speaking, as has been described by PAN et all (17, 18, 22), transglucosidation of mal-tose into unfermentable oligosaccharides plays an important role upon the rate of fermentable sugar formation from starch with the solution of those mold enzymes. Without yeast, the effect of the action continues to appear up to the secondary phase of hydrolysis. In the presence of yeast, the effect disappeares rather fast on account of the reconversion of the presynthesized unfermentable oligosaccharides into fermentable sugars by the rapid yeast removal of maltose and the reversibility of transglucosidase. This makes the difference between the two curves, Ta (total fermentable sugars produced in the absence of yeast) arid Tp, (total fermentable sugars produced in the presence of yeast). It however, is not always as vivid as in Fig. 2., because the degree of the transglu-cosidation reaction is different in each enzyme solution, due to their different transglucosidase activity and their different value of D/G. D. (ratio of α-amylase to saccharogenic amylase). 4. It was concluded that the “Glucose-Direct” activity shows close correlation to the velocity of starch attenuation in the presence of yeast.

Extent of hydrolysis of starches by amylases in the presence and absence of yeasts

Extent of hydrolysis of starches by amylases in the presence and absence of yeasts

The Utilization of Wheat and Wheat By-Products in Feeding Young Chickens : IV. Ground Wheat as a Source of Vitamin G Growth Factor. Unknown Factors Which Affect Plumage Color and Structure

IT HAS been demonstrated that grains should be supplemented with water-soluble growth-promoting factors associated with the vitamin B complex if good growth is to be obtained. There seems to be some confusion as to the identity of growth factors other than the commonly recognized vitamins B (B1, antineuritic), and vitamin G (B2, flavin).3Hauge and Carrick (1926) showed that corn was rich in the antineuritic factor but relatively poor in a growth-promoting factor. Normal growth in chicks was obtained by supplementing the corn with dried yeast. Since no symptoms of pellagra were reported when the percentage of corn was low, although slow growth was obtained in the absence of yeast, it was apparent that the growth-promoting factor was not identical with the pellagric factor, but rather with some other factor, probably the vitamin G growth factor. Differentiation between the antineuritic, antipellagric, and growth factors of the vitamin B complex has .