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summary Field studies of Heliamphora nutans Benth., H. heterodoxa Steyerm., H. minor Gleason, H. ionasii maguire and H. tatei Gleason in the Guayana Highlands of Venezuela, show that the last named species is a true carnivore, possessing all of the following traits: attraction of prey through special visual and chemical signals, trapping and killing of prey, digestion of prey through secreted enzymes, presence of commensals, presence of wax scales aiding in the capture of prey, and absorption of nutrients. The other species possess all traits except they seem neither to secrete proteolytic enzymes nor produce wax scales. The pattern of the carnivorous syndrome among Heliamphora species suggests that the carnivorous habit has evolved in nutrient–poor habitats to improve the absorption of nutrients by capturing mainly ants and only H. tatei further evolved mechanisms for rapid assimilation of organic nutrients and for capturing a variety of flying insects. The carnivorous traits are lost in low light conditions, indicating that nutrient supply is limiting only under fast growth.

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Internalization of rotavirus in MA104 cells was found to induce coentry of alpha-sarcin, a toxin that inhibits translation in cell-free systems and to which cells are normally impermeable. Entry of the toxin, measured by inhibition of protein synthesis at early times after infection, correlated with virus penetration leading to expression of infectivity, since toxin entry (1) was induced only by trypsin-treated triple-layered virions, to a degree dependent on the toxin and the virus concentration; (2) correlated with the degree of permissivity of different cell lines to rotavirus infection; (3) was inhibited to a similar extent as infectivity by treatment of cells with neuraminidase; and (4) was inhibited by pre- or postadsorption incubation of the virus with neutralizing monoclonal antibodies to VP7 and VP4 (VP8*). Neither the virus infectivity nor the toxin coentry was significantly affected by treatment of cells with bafilomycin A1, an inhibitor of the vacuolar proton ATPase, indicating that both events are independent of the endosomal acid pH. Virus-like particles (VLP), composed of rotavirus proteins 2/6/7/4, but not 2/6/7 or 2/6, were able to induce toxin entry as efficiently as virions. Use of genetically modified VLP in combination with the toxin coentry assay, which measures entry through a productive pathway, should allow identification of the regions of the outer capsid proteins essential for rotavirus penetration.