Catabolite repression and derepression of arylsulfatase synthesis in Klebsiella aerogenes

When a mutant (Mao(-)) of Klebsiella aerogenes lacking an enzyme for tyramine degradation (monoamine oxidase) was grown with d-xylose as a carbon source, arylsulfatase was repressed by inorganic sulfate and repression was relieved by tyramine. When the cells were grown on glucose, tyramine failed to derepress the arylsulfatase synthesis. When grown with methionine as the sole sulfur source, the enzyme was synthesized irrespective of the carbon source used. Addition of cyclic adenosine monophosphate overcame the catabolite repression of synthesis of the derepressed enzyme caused by tyramine. Uptake of tyramine was not affected by the carbon source. We isolated a mutant strain in which derepression of arylsulfatase synthesis by tyramine occurred even in the presence of glucose and inorganic sulfate. This strain also produced beta-galactosidase in the presence of an inducer and glucose. These results, and those on other mutant strains in which tyramine cannot derepress enzyme synthesis, strongly suggest that a protein factor regulated by catabolite repression is involved in the derepression of arylsulfatase synthesis by tyramine.

Progesterone-induced lysis of rat kidney lysosomes as studied by changes in light-absorbance

1. A rat kidney lysosomal fraction was prepared by the method of Maunsbach (1966) and characterized by its content of representative marker enzymes for lysosomes, mitochondria, peroxisomes and endoplasmic reticulum. 2. It was shown that both pH-dependent and progesterone-induced lysis lead to a decrease in the E(520) of suspensions of this preparation. This decrease parallels quantitatively and temporally the release of soluble acid phosphatase. 3. It is suggested that E(520) measurements are a valid method for the continuous measurement of changes in lysosomal integrity. 4. As an example, results are included which demonstrate the ability of Zn(2+) to stabilize lysosomes against spontaneous and progesterone-induced lysis.

Lysosomal packaging in differentiating and degenerating anuran lateral motor column neurons

The role of the Golgi apparatus and the Golgi-endoplasmic reticulum-lysosome complex (GERL) in the genesis of lysosomes was examined in differentiating and degenerating motor neurons of anuran larvae. Acid phosphatase, aryl sulfatase, and thiolacetic acid esterase were utilized as marker enzymes for the lysosomal system, while nucleoside diphosphatase and thiamine pyrophosphatase labeled the inner saccule(s) of the Golgi apparatus. Reduced osmium tetroxide was routinely deposited in the outer Golgi saccule regardless of the state of neuronal maturation. In all young neurons, the disposition of acid hydrolase reaction product paralleled the formation of GERL, with no lytic activity in the Golgi apparatus per se. Hypertrophy of the Golgi apparatus and GERL was observed in the early phases of degeneration, and both organelles apparently exhibit extensive hydrolytic activity. Dense bodies, autophagic vacuoles, and primary lysosomes were found arising from GERL, while the Golgi apparatus may produce primary lysosomal granules during regression. On the other hand, in differentiating neurons, hydrolytic activity was restricted to GERL and an occasional dense body and autophagic vacuole. These studies illustrate a parallelism between the development of GERL and genesis of primary and secondary lysosomes during neuronal cytodifferentiation, and implicate GERL and possibly the Golgi apparatus in lysosomal packaging in degenerating neurons.

Cytochemical detection of hydrolases in fungus cells. 3. Aryl sulfatase

In the cells of Aspergillus oryzae, Aspergillus nidulans, Neurospora crassa and Saccharomyces cerevisiae, aryl sulfatase can be demonstrated by incubation in a medium containing 6-bromo-2-naphthylsulfate as substrate and fast garnet GBC as coupling agent. Controls confirm the specificity of the reaction. Other incubation solutions (two Gomori media and a simultaneous coupling procedure with 8-hydroxyquinoline sulfate as substrate) gave negative results or reaction pictures equally to those in substrate-free control. The possible reasons for this are discussed. In the mycelial fungi the strongest enzyme activity is located in the most intensely metabolizing parts: tips of the hyphae and the differentiating parts of the conidiophores. The reaction granules in all four fungi are possibly identical with lysosomes.