A complete chitinolytic system in the atherinopsid pike silverside Chirostoma estor: gene expression and activities.

The expression and digestive activity of pike silverside Chirostoma estor endogenous chitinases were analysed in samples from four life stages: whole eggs; larvae; juvenile intestine and hepatopancreas and adult intestine and hepatopancreas. A chitinase cDNA was cloned and partially sequenced (GenBank accession number: FJ785521). It was highly homologous to non-acidic chitinase sequences from other fish species, suggesting that it is a chitotriosidase. Quantitative PCR showed that this chitinase was expressed throughout the life span of C. estor, with maximum expression in the hepatopancreas of juveniles. Chitotriosidase and chitobiosidase activities were found at all life stages, along with a very high level of N-acetyl glucosaminidase (NAGase). The chitotriosidase activity could be encoded by the cloned complementary (c)DNA, although additional chitinase genes may be present. The chitotriosidase activity appeared to be transcriptionally regulated only at the juvenile stage. The expression and activity of chitinases tended to increase from the early to juvenile stages, suggesting that these variables are stimulated by chitin-rich live food. Nevertheless, the feeding of juvenile and adult fish with both live food and a balanced commercial diet seemed to provoke significant reductions in pancreatic NAGase secretion and/or synthesis in the gut. Moreover, all chitinase activities were lower in adults, probably reflecting a higher intake and use of the balanced diet. The observation of chitotriosidase and chitobiosidase activities together with a very high NAGase activity suggest the presence of a complete and compensatory chitinolytic chitinase system that enables this stomachless short-gut fish species to use chitin as an energy substrate. These novel findings suggest that dietary inclusions of chitin-rich ingredients or by-products might reduce the farming costs of C. estor without impairing performance.

[67Ga scanning in sarcoidosis]. / Die 67Ga-Szintigraphie bei der Sarkoidose

The value of 67Ga scans in selected cases of sarcoidosis was studied at various stages in order to assess its value as a supplement to clinical, radiological and perfusion studies. During stages I and II, radioactive gallium is taken up by the granulomatous nodes in the hilum and mediastinum and in the interstitial focal pulmonary infiltrates. After complete regression of the hilar and mediastinal lymphadenopathy or of the pulmonary infiltrates, radio-active uptake can no longer be demonstrated. Gallium scans are valuable in showing whether there is active granulomatous infiltration into the lungs when there is known scarring resulting in abnormal perfusion conditions. The gallium scan may indicate that further treatment is desirable. A comparison of serial radiographs and the 67Ga scan provides an indication of the activity of the granulomatous disease; a comparison of the radiological findings and of perfusion scans shows the severity of perfusion abnormalities caused by fibrosis. The investigation has shown that the granulomatous lesions persit even though radiological, clinical and functional investigations have indicated the presence of fibrotic scarring. Radiography, perfusion and gallium scans provide an understanding of the dynamics of this disease.