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T M Shinnick

Publications and source records attributed to T M Shinnick.

77 records · Page 5Linked to original sources

An extracellular inducer of asexual plasmodium formation in Physarum polycephalum.

Asexual conversion of amoebae to plasmodia was studied in the Colonia isolate of the myxomycete, Physarum polycephalum. When a culture of Colonia amoebae is grown on a bacterial lawn, a period of amoebic growth precedes the appearance of cells committed to the plasmodial state. The onset of plasmodium production appears to be related to amoebic nutrition since cultures supplied with fewer bacteria display earlier differentiation. For a period of time after differentiation is initiated, conversion of amoebae to plasmodia is rapid and proceeds as an exponential function of time. A filter-transmissible substance, apparently released by differentiating cells, is implicated in the control of this rapid conversion.

Cell Differentiation↗

A mutation (gad) linked to mt and affecting asexual plasmodium formation in Physarum polycephalum.

Amoebae of the acellular slime mold Physarum polycephalum convert to plasmodia both asexually and sexually. Genetic analysis of a mutant that exhibits enhanced asexual plasmodium formation is reported. The mutant carries a single lesion (gad-11) located 12.3 map units from mt, a gene that controls mating specificity in sexual plasmodium formation. The mutation, which was isolated in an mt3 strain, is also expressed in mth and mt4 strains.

Chromosome Mapping↗

Hybridization of labeled RNA to DNA in agarose gels.

Specific DNA restriction endonuclease fragments can be identified after electrophoresis in agarose gels by hybridization in the gel (in situ) to radioactive homologous RNA. RNA-DNA hybrids are detected by autoradiography of the gel. Comparison of band patterns of the autoradiogram and the ethidium bromide stained gel allows the identification of the DNA fragment which is complementary to the RNA probe. The technique is rapid, easy and inexpensive. It is sensitive enough to detect individual genes in a mixture of fragments produced by restriction enzyme digestion of complex cellular DNA. We have used this technique to determine which of the Hin III and Eco R1 fragments of phi80d3ilv+su+7 and E. coli DNAs contain the 5S, 16S and 23S ribosomal RNA (rRNA) genes of E. coli.

DNA↗