FACTORS AFFECTING SURVIVAL OF LYOPHILIZED FUNGAL SPORES AND CELLS

1957 ◽  
Vol 3 (3) ◽  
pp. 477-485 ◽  
Author(s):  
R. H. Haskins
Keyword(s):  
Low Temperatures ◽  
Fungal Spores ◽  
Puccinia Graminis ◽  
Percentage Germination ◽  
Vegetative Cells ◽  
Factors Affecting ◽  
Melampsora Lini ◽  
Percentage Survival ◽  
Initial Freezing ◽  
Preliminary Degassing

Spores of Alternaria, Aspergillus, Fusarium, Gliocladium, Penicillium, and Pestalotia, budding vegetative cells of Ustilago, and uredospores of Puccinia graminis, P. helianthi, and Melampsora lini were lyophilized using several techniques and various conditions. The best percentage survival of the lyophilized spores and cells was obtained when the initial freezing of the spore suspensions was just low enough to keep the suspension solid until evaporative freezing conditions were reached. Freezing to very low temperatures was unnecessary. Conditions permitting fast warming of the frozen suspension resulted in increased survival. A preliminary degassing treatment greatly enhanced percentage germination, as did the conditioning of the spores in a moist atmosphere immediately after the opening of the tubes for revival of the organisms.

In vitro growth of wheat and flax rust fungi on complex and chemically defined media

1974 ◽  
Vol 52 (6) ◽  
pp. 1183-1195 ◽  
Author(s):  
A. Bose ◽  
Michael Shaw
Keyword(s):  
Liquid Medium ◽  
Aspartic Acid ◽  
Yeast Extract ◽  
Australian Isolate ◽  
Puccinia Graminis ◽  
Good Growth ◽  
Complex Media ◽  
Mineral Salts ◽  
Melampsora Lini

Growth from uredospores seeded in axenic culture is described for several races of Puccinia graminis Pers. f. sp. tritici (Erikss. and Henn.) and race 3 of Melampsora lini (Ehrenb.) Lév. on complex media containing peptone, yeast extract, and bovine serum albumin (BSA); and for an Australian isolate of Puccinia graminis, race 126-ANZ 6,7, and Melampsora lini, race 3, on chemically defined, liquid media.Of six North American isolates of Puccinia graminis only race 38 formed colonies approaching those of race 126-ANZ 6,7 in final size and general morphology on complex media. 5′AMP had no effect on the growth of 126-ANZ 6,7, but cyclic AMP inhibited growth after uredospore germination. Good growth and sporulation were obtained with 126-ANZ 6,7, but not with the other isolates tested, using a new, chemically defined liquid medium, sterilized by millipore filtration, and containing glucose, Czapek's minerals plus micronutrients, Ca2+, glucose and aspartic acid, glutathione, and cysteine. Uredospores produced in culture reinfected exposed mesophyll tissue, but not intact seedling leaves of wheat.Highly reproducible growth and sporulation of Melampsora lini, race 3, were obtained routinely on a solid medium containing Difco-Bacto agar, sucrose, Knop's minerals, micronutrients, yeast extract, peptone, and BSA. Vegetative cultures, capable of reinfecting the cut ends of surface-sterilized flax cotyledons, could be maintained indefinitely by subdivision before sporulation and transfer to the same medium minus BSA. Evidence is presented that BSA stimulated the development of colonies and the formation of uredospores. The mode of action of BSA is unknown, but it could not be replaced by putrescine.A new chemically defined, liquid medium containing sucrose, Knop's mineral salts, micronutrients, aspartic (or glutamic) acid, and cysteine supported the growth of colonies of Melampsora lini in a highly reproducible manner. The formation of uredospores and teliospores by these colonies was controlled by (a) the level of Ca2+ (as Ca(NO3)2∙4H2O), (b) the concentration of aspartic acid, and (c) the number of colonies per flask. At inoculum levels giving 40 to 60 colonies per flask, in media containing 8.5 mM Ca+ and 45 mM aspartic acid, uredospore formation occurred in 60 to 70% of the colonies. A decrease in the Ca2+ level to 4.25 mM, or a decrease in aspartic acid to 22.5 mM, or adjustment of the inoculum level to give about 10 colonies per flask each resulted in only infrequent sporulation. The uredospores produced in vitro infected intact, 1-week-old flax cotyledons in a normal manner.

Factors Affecting Johnsongrass Rhizome Production and Germination

Weed Science ◽  
1972 ◽  
Vol 20 (1) ◽  
pp. 41-45 ◽  
Author(s):  
C. G. McWhorter
Keyword(s):  
Soil Profile ◽  
Clay Soil ◽  
Sandy Loam ◽  
Sorghum Halepense ◽  
Percentage Germination ◽  
Factors Affecting ◽  
Opposite Trend ◽  
Rhizome Buds

Approximately 80% of the johnsongrass(Sorghum halepense(L.) Pers.) rhizomes produced in clay soil were in the top 7.5 cm, but 80% of the rhizomes in sandy loam occurred in the top 12.5 cm. Distribution of rhizomes within the top 20 cm of soil was more uniform in sandy loam than in clay; yet, 5% of the rhizomes produced in clay occurred deeper than 20 cm, but only 1% of the rhizomes in sandy loam occurred deeper than 20 cm. Incorporation ofa,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-/7-toluidine (trifluralin) in soil at 0.84 kg/ha reduced rhizome production approximately 50% throughout the soil profile but reduced rhizome production most in the top 6 cm. More plants emerged from rhizomes when planted in sandy loam than in clay. More plants emerged from short rhizomes (76 mm) than from long rhizomes (152 mm) when planted at depths to 7.6 cm, but the opposite trend was obtained when rhizomes were planted deeper. Percentage germination of rhizome buds increased as rhizomes were cut into smaller pieces. Exposure of rhizomes to temperatures of 50 to 60 C killed buds within 1 to 3 days. Rhizomes usually survived temperatures of −3 to −5 C for only a few hours.

Factors affecting seed set in Douglas-fir (Pseudotsuga menziesii)

1991 ◽  
Vol 69 (2) ◽  
pp. 229-238 ◽  
Author(s):  
John N. Owens ◽  
Anna M. Colangeli ◽  
Sheila J. Morris
Keyword(s):  
Reproductive Success ◽  
Pseudotsuga Menziesii ◽  
Low Temperatures ◽  
Seed Set ◽  
Douglas Fir ◽  
Ovule Development ◽  
High Moisture ◽  
Embryo Abortion ◽  
Factors Affecting ◽  
Major Loss

Cone and seed development in Douglas-fir were studied from pollination until seed release in 1986. Cone abortion at, and shortly after, pollination was high, resulting from a combination of low temperatures and possibly high moisture and populations of microorganisms on cones. Seed potential averaged about 75 seeds per cone with 31 filled seed per cone, giving an average seed efficiency of 39%. The major loss of seed resulted from insufficient pollen in the ovules. Other causes were ovule and embryo abortion at various stages of development. The effects of prezygotic and postzygotic events on seed set are discussed with respect to the reproductive success of Douglas-fir. Key words: Douglas-fir, seed set, cone, ovule, development, abortion.

THERMAL STABILITY OF STEM RUST RESISTANCE IN OAT SEEDLINGS

1967 ◽  
Vol 45 (4) ◽  
pp. 451-458 ◽  
Author(s):  
J. W. Martens ◽  
R. I. H. McKenzie ◽  
G. J. Green
Keyword(s):  
Stem Rust ◽  
Avena Sativa ◽  
Low Temperatures ◽  
Rust Resistance ◽  
Thermal Sensitivity ◽  
Stem Rust Resistance ◽  
Puccinia Graminis ◽  
Physiologic Race ◽  
Plant Genotype ◽  
Thermal Stability Of

Six of the identified genes for stem rust (Puccinia graminis Pers. f. sp. avenae Erikss. and Henn.) resistance in oats (Avena sativa L.) are divided into three categories of thermal sensitivity: resistance conferred by genes A and D is stable; that conferred by genes H and F 'breaks down' at intermediate temperatures; and that conferred by genes B and E breaks down at relatively low temperatures. Studies of oat lines carrying single or several resistance genes indicate that thermal sensitivity of the reactions conditioned by the genes conferring labile resistance is not affected by the presence of genes conferring stable resistance or by the rest of the host plant genotype. The critical temperature of breakdown varies with physiologic race.

ENVIRONMENTAL AND PHYSIOLOGICAL FACTORS REGULATE FLOWERING

1998 ◽  
Vol 46 (1) ◽  
pp. 47-51
Author(s):  
Osnat Ohana ◽  
David Weiss
Keyword(s):  
Genetic Variation ◽  
High Temperature ◽  
Flowering Time ◽  
Low Temperatures ◽  
Apical Meristem ◽  
Flowering Plants ◽  
Cut Flower ◽  
Physiological Factors ◽  
Factors Affecting ◽  
Bud Size

Eryngium planum was introduced as a cut flower in Israel 20 years ago. So far, all efforts to hasten and synchronize flowering time have failed. In the present work we study the factors affecting eryngium flowering. We found that variation in flowering time is not caused by genetic variation but probably by physiological factors. Exposure of root cuttings to low temperature (2 °C for 2 months) enhanced the percentage of flowering plants but did not shorten time to flowering. High temperature during growth inhibited flowering in vernalized plants, probably via devernalization. Gibberellic acid (GA3) had little, if any, effect on either flowering time or quantity. The size of the initiated bud on the root cuttings was related to flowering time and quantity. Plants from vernalized roots with large buds bloomed faster and at a higher percentage than those from roots with smaller buds. It is suggested that the ability to respond to inductive low temperatures is related to the size of the apical meristem, which is correlated to bud size.

The Survival of Listeria monocytogenes on Fingertips and Factors Affecting Elimination of the Organism by Hand Washing and Disinfection

1991 ◽  
Vol 54 (5) ◽  
pp. 343-348 ◽  
Author(s):  
ANNA M. SNELLING ◽  
KEVIN G. KERR ◽  
JOHN HERITAGE
Keyword(s):  
Listeria Monocytogenes ◽  
Chlorhexidine Gluconate ◽  
Hand Washing ◽  
Normal Flora ◽  
Survival Times ◽  
Factors Affecting ◽  
Skin Lipids ◽  
Percentage Survival ◽  
Water Based ◽  
Elution Method

The survival of Listeria monocytogenes applied to the fingertips was investigated using both an impression plate and an elution method. When suspended in saline, L. monocytogenes NCTC 9863 survived for up to 60 min on fingertips, but survival times were greatly extended when the inoculum was suspended in milk. Survival was not apparently affected by skin lipids, the skin's normal flora, or the fat content of the milk. Different serotypes displayed similar results for the percentage persistence over a 2-h period when suspended in milk except for an isolate of L. monocytogenes serotype 7 which had a greater percentage survival than other organisms tested. In contrast, Escherichia coli C600 failed to survive for one hour under the same conditions. Hand washing with either soap or a water-based chlorhexidine hand cleanser usually failed to decontaminate fingertips to which an inoculum of 104/CFU per fingertip suspended in milk was applied, but a solution of chlorhexidine gluconate in methanol was found to be effective.

Cold-induced lipid phase transitions

1990 ◽  
Vol 326 (1237) ◽  
pp. 555-570 ◽  
Keyword(s):  
Low Temperatures ◽  
Membrane Lipids ◽  
Weak Interactions ◽  
Protective Action ◽  
Biological Membranes ◽  
Membrane Lipid ◽  
Phase Behaviour ◽  
Lipid Phase ◽  
Aqueous Environment ◽  
Factors Affecting

The structural organization of biological membranes is largely determined by the weak interactions existing between their components and between these components and their aqueous environment. These interactions are particularly sensitive to changes in temperature and hydration. The factors influencing membrane lipid phase behaviour are briefly reviewed and used to develop a phase-separation model describing the response of biological membranes to stress. The factors affecting the interaction of cryoprotectants with membrane lipids are explored and their role in the stabilization of membrane organization at low temperatures discussed. It is suggested that the basis of their protective action lies in an ability to preserve the balance of interactions between membrane components at low temperatures at a level similar to that existing under physiological conditions.

scholarly journals Risk Comparison of the Diarrheal and Emetic Type of Bacillus cereus in Tofu

2019 ◽  
Vol 7 (11) ◽  
pp. 536 ◽  
Author(s):  
Mi Jin Kwon ◽  
Chae Lim Lee ◽  
Ki Sun Yoon
Keyword(s):  
Stainless Steel ◽  
Bacillus Cereus ◽  
Low Temperatures ◽  
Biofilm Formation ◽  
Planktonic Cells ◽  
High Concentration ◽  
Vegetative Cells ◽  
And Behavior ◽  
Resistance To Heat

We investigated the ability of biofilm formation, survival, and behavior of diarrheal and emetic Bacillus cereus vegetative cells and spores in tofu. Both diarrheal and emetic B. cereus did not proliferate at a temperature below 9 °C in tofu. However, the emetic B. cereus grew faster than diarrheal B. cereus at 11 °C and had better survival ability at low temperatures. Both diarrheal and emetic B. cereus were able to form a biofilm on stainless steel. These biofilm cells were transferred to tofu in live state. The transferred biofilm cells could not grow at a temperature below 9 °C but grew over 11 °C, like planktonic cells. B. cereus contamination in tofu at a high concentration (>6 logs CFU/g) was not entirely killed by heating at 80, 85, or 90 °C for 2 h. Spores and emetic B. cereus had higher resistance to heat than vegetative cells and diarrheal B. cereus, respectively.

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