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Exudation-reabsorption in a mycorrhizal fungus, the dynamic interface for interaction with soil and soil microorganisms (1999)

Sun, Yu-Ping ; Unestam, T. ; Lucas, Steven D. ; [et al.]

Springer

Mycorrhiza 9 (1999), S. 137-144

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ISSN: 1432-1890

Keywords: Key word Exudation ; Reabsorption ; Mycelium-soil interface ; Osmotic gradient pump ; Carbon and water translocation

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract The mycelium of Suillus bovinus slowly absorbed [U-14C]glucose and other tracers from droplets placed on the cords, translocated them to the peripheral hyphae and exuded them into fluid drops on the hyphal tips. The exudate was characterized by 1H NMR spectroscopy and by sugar and amino acid analysis. The exuded compounds were mainly carbohydrates and peptides. Acetic acid and oxalic acid were also present in the exudate along with a number of unidentified compounds. Released ions (K, Na, Cl, P, Mg and Ca) were identified by X-ray microanalysis. The mycelium was shown to reabsorb up to 65% of the exuded 14C compounds in 2 days. Glucose, mannitol, glutamic acid (pH 3.2), and Rb+ (as well as other mineral ions) were all readily absorbed by the mycelium, while oxalic acid at pH 4.2 and glutamic acid at pH 6.5 were not. Exudation of fluid droplets on the surface of the hydrophobic mycorrhizal fungus S. bovinus may represent an ecophysiologically important function of the extramatrical hyphae, which provides an interface for interaction with the immediate hyphal environment and its other microorganisms where the peripheral hyphae exchange their photosynthetically derived products for nutrients to be used later by the pine host. We hypothesize that actively absorbed carbohydrates from the root are translocated to the peripheral hyphae along a concentration gradient of sugars and polyols by means of active translocation and diffusion in cell elements and by acropetal water transport in the cord vessels.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s005720050298

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Fetal loss in mice exposed to magnetic fields during early pregnancy (1995)

Svedenstål, Britt-Marie ; Johanson, Karl-Johan

New York, NY [u.a.] : Wiley-Blackwell

Bioelectromagnetics 16 (1995), S. 284-289

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ISSN: 0197-8462

Keywords: mouse ; embryogenesis ; implantation ; resorption ; malformation ; magnetic field ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Physics

Notes: The effects of low-frequency magnetic fields (MFs) on early pregnancy were studied in CBA/S mice. The magnetic field was a 20 kHz, 15 μT sawtooth. Pregnant females were divided into four groups, two control groups and two exposed groups. One group was exposed to MFs continuously from day 1 postconception (pc) until day 5.5 pc, and the other group was exposed continuously until day 7 pc. All animals were sacrificed on day 19 pc, the day before partus, and their uterine contents were analyzed. No significant increase in the resorption (early fetal death) rate was found in the exposed animals compared to the sham controls. In the group exposed during days 1.0-5.5 pc, the body weight and length of the living fetuses were significantly decreased. Except on day 3 pc (progesterone) and day 13 pc (calcium) in the treated groups, there were no significant differences in progesterone and calcium levels in peripheral blood. Implantation occurred on the same day in MF-treated and control animals. © 1995 Wiley-Liss, Inc.

Additional Material: 6 Ill.