Fruit Body Size Research Articles

Shiitake cultivation: Gas phase during incubation influences productivity

To test the effects of gas levels during incubation on mushroom production, we grew two strains of shiitake, Lentinula edodes, on a sawdust medium inside plastic mushroom-growing bags having different amounts of ventilation. During 77 days of incubation, oxygen and carbon dioxide levels inside the bags varied with: 1) the fungus strain, 2) the metabolic activity and stage of development of the fungus, and 3) the size of the microporous filter patch ventilating the bag. Total mushroom yield, fruitbody size, the number of mushrooms produced, and the severity of contamination during cropping were affected by filter patch size. Each strain required a different amount of ventilation in order to achieve optimum mushroom production.

Evolutionarily stable stalk to spore ratio in cellular slime molds and the law of equalization in net incomes

The evolutionarily stable stalk ratio (ESSR) in the cellular slime molds is studied when the fruiting body is formed by multiple clones of various size. The survival probability of a spore cell is assumed to depend on the stalk ratio and the fruiting body size. ESSR is obtained as the non-co-operative equilibrium (Nash solution) that maximizes the fitness of each clone. The following two predictions are obtained: (1) the number of spore cells produced by each clone forming a fruiting body tends to be equalized, even if a variation in clone size exists. As a result, the larger clones do not necessarily enjoy higher fitness than the smaller ones. (2) The stalk ratio and the overall fitness of the fruiting body decrease as the genetic diversity in the fruiting body increases. A condition for the stalk to spore ratio to be invariant of overall fruiting body size is also investigated. Finally, "the law of equalization in net incomes" is proposed, extending result (1) into the broader range of resource allocation problems.

5-Iodo-2′-deoxyuridine inhibition of Dictyostelium discoideum differentiation and cyclic AMP phosphodiesterase activity

5-Iodo-2′-deoxyuridine (IdUrd), at a concentration of 0.25 mM, had little or no effect on the growth of Dictyostelium discoideum for at least four doubling times. However, when these cells were allowed to differentiate, the number of fruiting bodies obtained was only about half of that obtained from cells grown in normal medium, and a great majority of them were about 1 4 to 1 8 the size of normal fruiting bodies. The inhibition of differentiation could be reversed if the cells were washed free of IdUrd and grown in normal medium for two generations before differentiation. If the IdUrd-grown cells were mixed with only 15 per cent as many normal cells just prior to differentiation, there was no inhibition of differentiation. Since it is known that, as a thymidine analogue, IdUrd can be incorporated into DNA, the induction patterns of several enzymes during growth and differentiation were compared in normal and IdUrd-treated cells. There was a continuous increase in the treated relative to untreated cells in the activities of the enzymes N-acetyl-glucosaminidase, α-mannosidase, β-glucosidase and acid and alkaline phosphatases during growth. There was also an increase in activity relative to control cells for all of these enzymes except alkaline phosphatase during the differentiation of cells previously grown in medium containing IdUrd. The reverse, however, was found for 3′,5′-cyclic adenosine monophosphate (cAMP) phosphodiesterase. There was a decrease caused by IdUrd in both the extracellular and cellular phosphodiesterase activity during development. In contrast, during growth, although IdUrd treatment also reduced the extracellular phosphodiesterase activity, the cellular phosphodiesterase activity remained unchanged from control.

The effect of ammonia on fruiting body size and microcyst formation in the cellular slime molds

Either gaseous ammonia or ammonium salts directly control the size of fruiting bodies in Polysphondylium pallidum and a variant of Dictyostelium discoideum. However, the fruiting bodies of D. discoideum remain constant in size over a wide range of ammonia concentrations. In P. pallidum high concentrations of ammonia will induce microcyst formation, a developmental pathway that bypasses normal aggregation and fruiting. The effective concentrations of ammonia are within the range given off by the amoebae, and therefore, ammonia could conceivably be a controlling factor in slime mold development in nature.

Promotion of stipe elongation in Flammulina velutipes by a diffusate from excised lamellae supplied with nutrients

Flammulina velutipes fruit bodies were grown on partly decayed Populus tremuloides sawdust supplemented with wheat bran and malt extract. In each culture there was a gradation in fruit body size, which served to select test specimens at an early stage of growth. Diffusates collected in agar blocks were applied on the apex of decapitated stipes. Plain agar and dilute potato dextrose agar (PDA/2) alone had the same slight effect on growth. Lamellae placed on plain agar caused limited growth promotion. Lamellae on PDA/2 gave 100–150% more growth promotion than on plain agar during early development, but the activity decreased to zero during the middle of the stage of rapid elongation. Lamellae of that age had no effect on young stipes and the older stipes were insensitive to diffusate from young lamellae. Very small amounts of lamellae promoted stipe elongation. Potato extract alone did not stimulate production of the lamellar diffusate and glucose was less effective than the two nutrients combined. A delay of 2 h in applying lamellar diffusate reduced stipe elongation, and there was no response after 12 h delay. Pilear trama did not produce growth-promoting diffusate.

Effect of growth conditions on development of the cellular slime mould, Dictyostelium discoideum

ABSTRACT The effect of growth in the presence and absence of 86 mM glucose on fruiting-body number and size, fruiting-body proportions and morphogenesis in the slime mould Dictyostelium discoideum, strain Ax-2, has been investigated. Cells grown in the absence of glucose (N.S. cells) formed 2·1 times more fruiting bodies than glucose-grown cells allowed to differentiate under the same conditions and at the same cell density. Glucose fruiting bodies were 2·6 times larger than N.S. fruiting bodies. During aggregation, N.S. aggregation streams generally broke up into numerous secondary aggregation centres. Glucose streams generally did not break up but moved into the initial aggregation centre. Each secondary centre formed one small grex, whereas initial centres fragmented into several grexes which were larger than those formed from secondary centres. The preponderance of secondary centres in N.S. aggregation and of initial centres in glucose aggregation accounts for the difference in size and number of fruiting bodies. We speculate about the mechanism giving rise to the morphogenetic difference. The spore: stalk ratio was 3·95:1 in glucose fruiting bodies and 2·70:1 in N.S. fruiting bodies. This difference is not related to the difference in fruiting-body size because proportions are size invariant for both fruiting-body types. Some difference in the physiological mechanism which determines proportions is suspected.