Antagonism Between Malate and Ethylene in the Regulation of Avena sativa Coleoptile Elongation

Etiolated Avena sativa L. coleoptile sections were used to determinethe influence of C₂H₄ on in vivo and in vitro rates of CO₂ fixation,and to measure the influence of various permutations of C₂H₄,CO₂, and malate on growth. Whereas 1 mM malate or 320 µI^-1 CO₂ stimulated growth by approximately 100 per cent, inhibitionof growth by 10-8 µ I_-1 C₂H₄ was substantial only in thepresence of malate or CO₂ The increase in growth rate in responseto these two agents was eliminated by the simultaneous applicationof C₂H₄. The in vivo rate of dark [¹⁴C]bicarbonate fixationand in vitro enzymic assays of fixation were not measurablyinhibited by C₂H₄. These results are discussed in the lightof evidence which indicates that CO₂-stimulated growth is mediatedby dark fixation. The data do not support the view that C₂H₄inhibition of growth results from an inhibition of fixation,but suggests that C₂H₄ may inhibit some step in the processby which malate stimulates growth.     

Habitat preferences and carcase colonization by sheep blowflies in the northern North Island of New Zealand

Abstract. In urban Auckland, from September 1991 to May 1992, only six specimens of the Australian sheep blowfly, Lucilia cuprina, were collected in farmed parkland and in garden habitats. The common green blowfly, Lucilia sericata, was the most common calliphorid trapped in these habitats. Neither of the two Lucilia species were found in native bush remnants in urban or rural areas where Calliphora hilli was dominant. Similarly very few L.cuprina (0.3% of the total) were trapped in rural rubbish tips in January and February where the majority of blowflies were again L.sericata. These results are compared with data collected from pastoral habitats, where L.cuprina is the major cause of flystrike. Lucilia cuprina was reared from five out of ninety-nine carcases found in rural areas. Calliphora stygia and L.sericata were the most common blowflies colonizing carrion and were reared from 59% and 51% of the carcases respectively.