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The article presents information on the lyophilization method for the storage of slime molds and small soil amoebae over a longer-term. Amoebae, spores, or bacteria to be lyophilized are suspended in sterile 2% peptone broth. Enough suspension is dropped into sealed glass tubings filled with saturated filter paper strips. Calcium chloride and anhydrous calcium sulphate are added. The tube is plugged, heated, cooled and then connected to a water vacuum pump. The tube is then sealed from the mouth. The filter paper strips may be dropped into a tube of liquid growth medium if the lyophilized organism is axenic.

Amoebae of Dictyostelium discoideum, cultivated on bacteria as the sole nutrient, secrete into the medium a degraded, water-soluble form of the corresponding bacterial lipopolysaccharide. Amoeba-degraded polysaccharide of Salmonella london isolated from the culture medium of amoebae by the phenol-water method, was purified by fractional precipitation with ethanol. Its chemical analysis showed that it contained all the sugar constituents of the parent lipopolysaccharide including the glucosamine backbone of lipid A, as well as the O-acetyl groups linked to galactose units of the O-specific chains, and the N-acetyl groups linked to glucosamine units of the core. The degraded polysaccharide, however, was completely devoid of the ester- and amide-linked long chain fatty acids present in the lipid A component of the parent lipopolysaccharide. The molecular weight was determined as 15,400. Serological investigations showed that, as expected, the degraded polysaccharide of S. London retained its serological O specificity, but failed to sensitize erythrocytes for passive hemagglutination. When tested in mice the degraded polysaccharide was significantly less toxic as compared with the parent lipopolysaccharide. Chemical analysis of amoeba-degraded polysaccharide derived from Escherichia coli B/r led to analogous results, and it is concluded that amoebae of Dictyostelium discoideum contain esterases and amidases which specifically cleave the long chain fatty acids from the lipid A component of bacterial lipopolysaccharides. [ABSTRACT FROM AUTHOR]

Amoebae of the cellular slime mold Dictyostelium discoideum can be grown in submerged culture on Escherichia coil W7. This strain is deficient in the synthesis and decarboxylation of diaminopimelate, the amino acid specific for murein. With [³H]diaminopimelate-labeled FL coil W7, it was found that the murein lipoprotein complex (rigid layer) of the bacterial cell wall is degraded completely by the amoebae, and diaminopimelate is converted to lysine which is then incorporated into protein. Cleavage of the bond between N-acetylmuramic acid and L-alanine and release of alanine from the murein peptide side chain is shown in vitro. Several glycosidases which degrade the polysaccharide chains of the murein were separated and both muramidase and N-acetyl-β-D-glucosaminidase activity could be demonstrated. The amoebae also contain proteolytic and lipolytic enzymes which degrade the lipoprotein in vitro. From the lipid which is covalently bound to the protein, palmitic acid was released. All these hydrolases have an optimum of pH 3 which suggests a lysosomal origin. Amoebae of Dictyostelium discoideum strain ax-2, grown in a bacteria-free medium take up isolated murein lipoprotein complex. These amoebae contain, without prior growth on E. coli cells, the hydrolases which are responsible for the degradation of the murein lipoprotein complex and for the conversion of diaminopimelate into lysine. [ABSTRACT FROM AUTHOR]

1. Thirty species of Testacea were shown to have an extremely patchy horizontal distribution within a relatively uniform sward of Sphagnum recurvum, but to have a well-defined vertical distribution which was not a seasonal phenomenon. There was no indication of a correlation between the vertical distribution of Testacea on Sphagnum plants and their distribution in wet and dry habitats. In nearly all species, dead individuals (empty tests) reached their maximum in a lower zone than the living individuals of the same species. 2. Three species possessed zoochlorellae. Two of these, Hyalosphenia papilio and Amphitrema flavum, were largely restricted to the upper 6 cm of the Sphagnum, probably because of light requirements. The third species, A. wrightianum reached maximum numbers 4-10 cm down the plant and this may represent a balance between light requirements and the availability of peat and mineral particles for test construction. 3. Of the forms without zoochlorellae, Assulina muscorum occurred mainly in the top 6 cm, Nebela tincta was fairly evenly distributed on the Sphagnum and the remaining twenty-five species all showed maxima in the lower levels. 4. Evidence suggests that H. papilio and N. tincta react to adverse environmental conditions by encysting rather than by migrating. 5. Peat and mineral particles on the Sphagnum increase with depth and Testacea requiring these for their tests are largely restricted to the lower levels. Bog habitats contain little mineral matter and species using this in their tests are found mainly in fens. 6. The number of Testacea in a Sphagnum sward is estimated at 16,000,000 per m² with a biomass of about 1 gr/m². About 20,000,000 dead individuals (empty tests) per m² were recorded. [ABSTRACT FROM AUTHOR]