1985 - Mycological Society of America

28
RNA and protein synthesis suggesting both gene
activation and gene product accumulation. Both
ribosomal and poly (A+) mRNA are stimulated by
antheridiol. The pheromone affects the acetylation
of histones prior to mRNA synthesis and branch
initiation. In vitro measurements indicate that
antheridiol and a cytosol component (receptor).
dramatically stimulate transcription. We have also
measured the levels of RNA polymerase I1 during male
development utilizing immunological techniques.
Changes of protein populations during female
development have been examined. Most recently, an
antheridiol-induced basic polypeptide of 64,000
daltons (ABP) has been identified. The qualitative
synthesis of ABP commenced 30-60 minutes after
antheridiol addition and continued for 6 hours. ABP
synthesis in male E87 was detected throughout sexual
morphogenesis in matings with the female 734. Two
other species of Achlya also synthesized ABP in
response to antheridiol. Synthesis of the inducible
polypeptide was not associated with a general
branching response. Studies using actinomycin D
suggested a transcriptional control of ABP. We are
presently constructing a cDNA library and will be
screening this library for ABP sequences using
differential colony hybridization.
2. R. HOSFORD. Dept. of Biolopical Sciences, Central
Llashington University, El lensburn, \.!A SG926.
Mutinus xylogenus: a rare phalloid found in the
Amazon Basin.
A rare phalloid collected in the Amazon Basin, is
identified as Mutinus xylogenus. This, the third
known report of the species since 1855, extends the
range to Brazil and confirms a very narrow equatorial
distribution. The species is distinquished by its
1) minute size (up to 5 mn tall), 2) epixylous habit,
and 3) glebal mass covering the apex of the receptacle.
A1 though some workers have placed the species
in the monotypic genus Xylophallus, the author
retains it in the genus Mutinus.
R. J. HOWARD. E. I. duPont de Nemours & Co., Inc.
Agricultural Chemicals Department, Experimental
Station, Wilmington, DE 19898.
Freeze-substitution.
Freeze-substitution is a fixation and dehydration
technique for the preparation of specimens for microscopy.
Fixation is initially accomplished by
rapid freezing. Frozen samples are dehydrated,
chemically fixed with OsO at low temperatures,
embedded and thi n-secti odd. The technique offers
the enormous advantages of cryofixation in samples
that are examined in section: better preservation of
cellular structure (cf. J. Ultrastruct. Res. 66:224,
J. Cell Sci. 48:89, Protoplasma 103:281, Exp. Mycol.
5: 167) and new opportunities for imnunocytochemistry.
Freeze-substitution is ideally suited for the preparation
of cells grown in monolayers or suspension
but also can be used for the study of some tissues.
Each step in the freeze-substitution process will be
considered so that the interested investigator is
prepared for the afternoon demonstration.
YP:IGAXT i-IQ-PNOR, W. a. CX)RDON, and L. FEDERICK.
Howard University, Washington, DC 20059 Protein and
esterase patterns of isolates of a natural mutant of
. Pleuro~ra
--- -- . dodqei -----, a wi ld t w strain, and FJ. te~~i--
c9&-
Protein 3nd esterasn p.tterns of mycelial extdacts of
four isolates of a spontaneous mutant of Neurospora
. dcdaei s homthallic species, have been compared
L-.
with those of isolates of t!e wild type and of M.
-- terricola. Morpholcqically, the mutant is distinwished
from the wild type and from 3. terricola by
its round or peanut px?-sha@ ascos-mres t!at m~y
vary in n3unber from 8 to 16 psr ascus. Profiles were
separated on vertical polyacrylamide gel electrophoresis.
Clear differences have heen found between
protein profiles of the wild type, the mutant isolates,
and N. terricola. Twenty-tm protein bands
appear to distinguish the wild type of the species.
Isolates of the mutant have yielded patterns with
up to 30 separate banes. Sixteen bands have been
comn to all isolates studied. In the protein
profiles of the different isolates bands were
present that were unique to each strain. Distinct
differences hav? also ken noted in esterase
patterns of the strains studied.
F.-S. HU and J. CLARK School of Biological Sciences,
University of Kentucky, Lexington, Kentucky 40506.
Mitochondria of senescing Physarum polycephalum
plasmodia.
Plasmodia of the myxomycete Physarum polycephalum
undergo senescence after a period of growth as macroplasmodia
on agar medium, but appear to be immortal
when grown as microplasmodia in shake culture. These
and other culture studies were the basis for a
hypothesis that senescence is due to the infectious
degeneration of an organelle (mitochondrion) similar
to that reported in Podospora anserina mycelia.
Therefore, the mitochondria of young, senesci ng and
immortal plasmodia have been examined for differences
in morphological structure and DNA content. For
senescing plasmodia there appears to be an increase
in the number and size of spherical osmophilic bodies
that are present in the mitochondria, but to date no
indication of mi tochondri a1 DNA changes have been
found.
F.-S. HU, S. STEINER and J. CLARK School of Biological
Sciences, University of Kentucky, Lexington,
Kentucky 40506.
Phospholipids of Physarum polycephalum and Didymium
iridis.
Axenic semi-defined shake cultures of Phjsarum polycephalum
plasmodia and heat-killed bacteria supplemented
corn-meal agar cultures of Didymium iridis
plasmodia and myxamoeba were labeled with radioactive
phosphate and the phospholipids extracted with a
chloroform-methanol system. The individual phospholipids
were then isolated by 2-dimensional chromatography
on partially EDTA-impregnated silicic acid
paper, located by autoradiography and quantitated by
scintillation spectroscopy. The phospholipid composi
tion of Didymium i ridi s plasmodia is 38% phosphatidylethanolamine,
35% phosphatidylchol ine, 12%
phosphatidyli nosi to1 , 5$ phosphatidylserine, 4%
~hos~hatidvlalvcerol
- -- . 2.5% cardioli~id. 0.5% ~hosohatidic
acid and 4% unidentified lipids. -~he phospholipids
of Didymium iridis myxamoeba and ~hysarum
polycephalum plasmodia are,similar. A fraction of the
unidentified lipids are a1 kaline-stable s~hinaoli~ids.
some of which were sugar-contai ni ng and had t6e chro--
matographi c properties of sphi ngoglycol i pi ds. The
a1 kal ine-stable lipid composition of the P. polycep-
&plasmodium and Q. iridis myxamoeba were similar
in that they each contained four chromatographically
similar sphingolipids, while the D. iridis plasmodium,
on the other hand, displayed only a single major
alkaline-stable lipid.