Changes in phenol oxidases and superoxide dismutase during fruit-body formation of <Emphasis Type="Italic">Pleurotus </Emphasis>on sawdust culture

 Peroxidase and laccase activities increased rapidly up to the formation of primordia and then declined throughout the entire stage of fruiting. In the case of Pleurotus ostreatus, the level of Mn-dependent peroxidase was very low in primordia and fruiting stages but gradually increased with the growth of the fruit-body, whereas no activity was detected in Pleurotus sajor-caju during all growth stages. Superoxide dismutase activity was observed mainly at the fruiting stages. These results show that changes in concentration of lignin-related enzymes are associated with the fruiting process. Received: December 11, 2000 / Accepted: March 28, 2002     

Feeding of a benthic goby in a river where nektonic fishes are absent

The social structure and feeding behaviour of the benthic goby Rhinogobius sp. DA (dark type) were investigated in a small river in Shikoku, Japan, where nektonic fishes are absent. The gobies had overlapped home ranges but were often aggressive against conspecifics, especially of the same sex and similar body size. Their diet consisted mainly of aquatic invertebrates, but terrestrial invertebrates were also an important item. This contrasted with few terrestrial invertebrates in the diet of the conspecifics in an adjacent river harbouring a nektonic cyprinid fish. An increase in flow level greatly changed their feeding behaviour; on high flow days, a greater portion of the population appeared from the interstices of the bottom and more often rose into the water column to catch drift than on normal flow days. Plasticity of their feeding behaviour is discussed in terms of ecological release.