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Biomedical subjects

B S Littlewood

Publications and source records attributed to B S Littlewood.

6 recordsLinked to original sources
PubMed1980

Studies of ribosomal proteins of yeast species and their hybrids: gel electrophoresis and immunochemical cross-reactions.

The cytoplasmic ribosomal proteins (r-proteins) of seventeen yeast species of the genera Saccharomyces and Kluyveromyces were analyzed by one-dimensional gradient polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate. The electrophoretic patterns of cytoplasmic r-proteins from different species display extensive differences in both the 40S and the 60S subunit. Relatedness of species suggested by r-protein patterns correlates well with that based on DNA/DNA homology (Bicknell and Douglas 1970). Immunochemical cross-reactions and antibiotic susceptibility tests were also used to compare different species. Analyses of r-proteins from two different interspecific hybrids showed that their ribosomes were hybrid, containing r-proteins from both parents. These findings are discussed in relation to the evolution of yeast species and the regulation of expression of r-proteins in eucaryotes.

Anti-Bacterial Agents↗
PubMed1975

Genetic control of phosphate-metabolizing enzymes in Neurospora crassa: relationships among regulatory mutations.

In Neurospora crassa, the phosphate-metabolizing enzymes are made during phosphate starvation, but not under phosphate sufficiency. The synthesis of these enzymes is controlled by three regulatory genes: pcon-nuc-2, preg and nuc-1, pcon-nuc-2 and preg are closely linked. A model of the hierarchical relationships among these regulatory genes is presented. Studies of double mutants and revertants confirm several predictions of the model. It has been found that nuc-2 (null) and pcon-c (constitutive) mutations reside in the same cistron. preg-c (constitutive) mutations are epistatic to nuc-2 mutations. nuc-1 (null) mutations are epistatic to all others.

Alkaline Phosphatase↗
PubMed1974

Genetic control of alkaline phosphatase synthesis in Neurospora: the use of partial diploids in dominance studies.

In wild-type Neurospora, alkaline phosphatase is made under conditions of phosphate limitation, but not conditions of phosphate sufficiency. Mutants at two unlinked loci, nuc-1 and nuc-2, do not make alkaline phosphatase under any conditions, while mutants at two quite closely linked loci, pcon and preg, make alkaline phosphatase even under conditions of phosphate sufficiency. pcon is extremely closely linked to nuc-2. nuc-2 and preg(c) (constitutive) mutants are recessive to their wild-type alleles in partial diploids as well as in heterokaryons, while pcon(c) mutants are dominant or co-dominant. nuc-1 is epistatic to both pcon(c) and preg(c) mutants. The implications of these findings for theories of metabolic control in eukaryotes are briefly discussed.

Alkaline Phosphatase↗