Pyruvate Metabolism by Mitochondria from Dormant and Activated Phycomyces blakesleeanus Spores

Abstract

~~Activation of Phycomyces blakesleeanus spores resulted in the production of large amounts of pyruvate and 2-oxoglutarate. Incubation of dormant spores in 0.1 M-pyruvate at pH 3 resulted in a high internal pyruvate concentration but no 2-oxoglutarate was formed and neither germination nor respiration was stimulated. The capacity of isolated mitochondria to decarboxylate [ l-'4C]pyruvate was doubled by heat activation of the spores. This difference in activity disappeared when the mitochondria were subjected to treatments attacking the integrity of the mitochondrial membrane (detergent, resuspension in buffer without osmotic stabilizer). The increase in pyruvate decarboxylating activity was found only after heating the spores at temperatures also triggering germination of the spores. Pyruvate uptake by the mitochondria seems, therefore, to be a limiting factor in dormant spore metabolism.

Stimulation of Phosphofructokinase from Phycomyces blakesleeanus and Some Other Fungi by Micromolar Concentrations of Fructose 2,6-bisphosphate

“…The most prominent biochemical feature of germinating spores is a large increase in glycolytic activity. This is manifested by an increased oxygen uptake and the production of large amounts of glycerol (Furch et al, 1976), pyruvate (Rudolph et al, 1966;Van Laere et al, 1982) and lactate (Furch, 1972) during early germination. An increased glycolytic activity was also found after activation of Neurospora ascospores (Eilers et al, 1970).…”

Functional Characteristics of Pyruvate Transport inPhycomyces blakesleeanus

“…The rate of pyruvate metabolism at pH 3.0 in dormant Phycomyces spores is comparable with that of glucose metabolism, showing pyruvate accumulation but no detectable oxoglutarate (van Laere et al, 1982). It has been reported (Hilgenberg et al, 1987) that magnesium lactate supports some growth of Phycomyces when used as a carbon source.…”

Conidial germination of marine-derived fungi under simulated deep-sea conditions in the presence of inducers

“…In each pouch with 1/5 th strength malt extract broth (MEB, HiMedia, M255, India) a final volume of conidial suspension at a concentration of 30-50 × 10 6 conidia mL -1 was transferred and subjected to various chemical inducertreatments and brief heat treatment. The chemical inducers (filtered through 0.22 µm pore sized filters) and their final concentrations used in this study were: Hydrochloric acid (Qualigen 29147, India) and Sulphuric acid (Qualigen Q29997, India) at 0.02 N (Lewis et al 1991), Sodium pyruvate (Fluka 15990, India) at 0.1 M (Laere et al 1982), Thiamine (HiMedia CMS182, India) at 0.1 mg L -1 (Siqueira et al 1982) and Sucrose (SD Fine chemicals, 20274, India) at 4 g L -1 . Details of the contents (1 mL volume) of the pouches for each set (of 12 pouches) are as follows: conidia (final concentration in pouch was 30-50 × 10 5 conidia mL -1 ) and 1/5 th strength MEB were common to all the pouches.…”