Browsing by Author "Illing, N"

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    Use of metabolic inhibitors to elucidate mechanisms of recovery from desiccation stress in the resurrection plant Xerophyta humilis.
    (Springer, 1998) Dace, H; Sherwin, H; Illing, N; Farrant, J
    Xerophyta humilis (Bak.) Dur. and Schinz is a poikilochlorophyllous resurrection plant in that it is tolerant of considerable water loss (< 5% relative water content [RWC]) and thylakoid membranes are dismantled and chlorophyll is lost during dehydration. In this paper we examined the processes associated with recovery from desiccation upon rehydration. Dried leaf explants were rehydrated in water (control) or in solutions of actinomycin-D or cyclohexamide in order to determine to what extent initial recovery was dependant on de novo transcription and translation respectively. Our results suggest that considerable protection of subcellular organisation and components of metabolism occurs during drying such that the initial recovery of metabolism on rehydration is virtually independent of de novo transcription of nuclear genes. However recovery does require the synthesis of new proteins. The plasmalemma remains intact and macromolecular synthesis is not required for maintenance of its integrity. Messenger RNA's for chlorophyll biosynthesis appear to be stored in a stable form in the dried leaves and are translated on rehydration. Similarly most of the mRNA's necessary for recovery of electron transport in the chloroplast (as determined by measuring the quantum efficiency of photosystem II [FV/FM] using chlorophyll fluorescence) appear to be stabily present in the dried leaves. However, for total recovery of FV/FM new genomic transcription is necessary.
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    Were Malagasy Uncarina fruits dispersed by the extinct elephant bird?
    (2009) Midgley, J J; Illing, N
    We hypothesise that the spiny fruits of the endemic Madagascar genus Uncarina (Pedaliaceae) are trample burrs that evolved to be dispersed on the feet of the extinct elephant bird (Aepyornis). Our evidence is : i) the morphology of the fruit with its large grapple hooks is more likely to attach to a foot than to adhere to fur and ii) the presentation of mature fruits on the ground rather than in the canopy. These differences to adhesive burrs make lemurs unlikely dispersers. We argue, given the absence of other large terrestrial mammals in Madagascar, that the most likely dispersers of Uncarina fruits were the extinct large birds. If correct, our hypothesis has implications for conservation of Uncarina, the biogeography of the elephant birds and dispersal biology. For example, we predict that the demography of Uncarina will be skewed towards adult plants, and that the dispersal mutualism could possibly be rescued by domestic animals.