spiA, a marker for sporulation, is expressed during the culmination stage of Dictyostelium development, when the mass of prespore cells has moved partly up the newly formed stalk. Strains containing a full-length spiA promoter/lacZ fusion were stained for beta-galactosidase activity at intervals during development. The results indicate that expression of spiA initiates in prespore cells at the ...

Cyclic adenosine 3’,5’-monophosphate (cyclic AMP) increases the differential rate of synthesis of @-galactosidase in Escherichia coli made permeable by treatment with t&(hydroxymethyl)aminomethane and ethylenediaminetetraacetic acid. In normal, growing cells, cyclic AMP overcomes the transient repression of /3-galactosidase by glucose. A half-maximal effect of cyclic AMP occurs at about 7 x 10-...

The hok/sok locus, isolated from the multiple-resistance plasmid R1 of Escherichia coli, is very efficient at ensuring the stable maintenance of plasmids in Gram-negative systems by killing plasmid-free cells as they arise. To investigate independently the influence of temperature and growth rate on the effectiveness of hok/sok, continuous fermentations have been conducted with the pUC-based, I...

The genetic and physiological control of ,(galactosidase in Escherichia coli has been the subject of extensive investigations. It has been clearly shown that the presence of this inducible enzyme is dependent on the genic constitution of the cell (Lederberg et al., 1951). In many cases gene mutation has led to a complete loss of ability by the cell to produce the enzyme; in other instances a de...

The umu test system is a newly developed method to evaluate genotoxicities of a wide variety of environmental carcinogens and mutagens (Oda et al., 1985; Nakamura et al., 1987). In the present study, SOS-inducing activity of 142 synthetic dyes was investigated by the umu test using Salmonella typhimurium (TA1535/pSK1002) under the condition of absence and presence of rat liver microsomal fracti...

Cellular senescence is a state of irreversible growth arrest. In this paper the authors examined whether bleomycin, an agent that causes pulmonary fibrosis, induces the senescence of alveolar epithelial cells. Type II-like alveolar epithelial (A549) cells or rat primary type II cells were exposed to bleomycin and then evaluated for markers of cellular senescence. Bleomycin was also administered...

An expression system utilizing specialized ribosomes has been constructed with beta-galactosidase as the product. Ribosomes specific for lacZ mRNA are generated due to a mutation within the anti-Shine-Dalgarno region of a plasmidborne 16S rRNA gene that is complementary to a mutation within the ribosome-binding site of lacZ. Hence, a subpopulation of ribsomes specific for translation of the clo...

Cyclic adenosine 3’,5’-monophosphate (cyclic AMP) increases the differential rate of synthesis of @-galactosidase in Escherichia coli made permeable by treatment with t&(hydroxymethyl)aminomethane and ethylenediaminetetraacetic acid. In normal, growing cells, cyclic AMP overcomes the transient repression of /3-galactosidase by glucose. A half-maximal effect of cyclic AMP occurs at about 7 x 10-...

The synthesis of galacto-oligosaccharides (GOS) by β-galactosidase immobilized in both polyvinyl alcohol (PVA) lenses and sol-gel carriers was studied and compared with the performance of the free enzyme. PVA-immobilized β-galactosidase retained 95 % of the initial activity after seven repeated uses and retained 51 % of the initial activity after 3 months of storage, while sol-gel-immobilized β...

N-Alkylation at the ring nitrogen of the D-galactosidase inhibitor 1-deoxygalactonojirimycin with a functionalised C ₆alkyl chain followed by modification with different aromatic substituents provided lipophilic 1-deoxygalactonojirimycin derivatives which exhibit inhibitory properties against β-glycosidases from E. coli and Agrobacterium sp. as well as green coffee bean α-galactosidase. In prel...