Beetle dytiscid

Scheme 18 Synthesis of mirasorvone from dytiscid beetles...

Of several related steroids in the defensive secretion of dytiscid beetles, deoxycorticosterone was most effective. It deterred simfish from feeding in 94% of the tests. Other steroids (pregnolones) that differed only by lacking a keto group at one carbon atom were either intermediate or not active at all (Gerhart etal., 1991). 

The presence of secondary metabolites in organisms has been proposed as an adaptation against predation [56, 57, 58, 59, 60, 61]. Secondary metabolites, toxic or inhibitory to a range of predators, have been isolated from a whole host of different organisms. Secondary metabolites originating from such diverse organisms as dytiscid beetles, (62], tropical seaweeds [63], gorgonians [64. 65] and sea hares [66] have been shown to exhibit anti-predatory properties. 

In Acheta (Lima-de-Faria et al., 1969) and the Dytiscid water beetles (Gall et al.,... 

The dytiscid beetles seem to represent an interesting intermediate between the typically panoistic and meroistic conditions. Morphologically they clearly belong to the meroistic type of ovariole development and nurse cells are actively engaged in the synthesis and transport of RNA into the oocytes. However, the oocyte nucleus also amplifies some of its nuclear DNA which results in the formation of a conspicuous Giardina s body (Urbani and Russo-Caia, 1964, 1969 Bier et al, 1967 Ficq and Urbani, 1969). 

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