Browsing by Author "Flores, Veronica"

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    Morphological convergence in the inter-holdfast coalescence process among kelp and kelp-like seaweeds (Lessonia, Macrocystis, Durvillaea)
    (2015) Gonzalez, Alejandra V.; Beltran, Jessica; Flores, Veronica; Santelices, Bernabe
    In brown macroalgae, intraspecific holdfast coalescence has only been studied in two species of Lessonia (Lessonia spicata and Lessonia berteroana). In both species coalescence followed the same general pattern: once the connection between holdfasts was established, the contact areas showed significant cellular morphological modifications. Typical epidermal cells became polygonal and similar to cortical cells. In addition, coalescence involved the de novo formation of secondary plasmodesmata, establishing a direct cytoplasm connection within neighbouring cells, where dense materials, vacuoles and organelles can be observed. In the present study, we demonstrate intraspecific holdfast coalescence in two additional kelp species, Lessonia trabeculata and Macrocystis pyrifera, as well as in the kelp-like seaweed, Durvillaea antarctica. The process of holdfast fusions in these species is similar to that described previously and suggests that this is a generalized phenomenon among kelp and kelp-like brown algae. In addition, the formation of cytoplasmic connections between genetically different brown algal individuals is shown for the first time.
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    SIZE INCREMENTS DUE TO INTERINDIVIDUAL FUSIONS: HOW MUCH AND FOR HOW LONG?1
    (2010) Santelices, Bernabe; Alvarado, Jorge L.; Flores, Veronica
    Size increments following interindividual fusions appear as a general benefit for organisms, such as coalescing seaweeds and modular invertebrates, with the capacity to fuse with conspecifics. Using sporelings of the red algae Gracilaria chilensis C. J. Bird, McLachlan et E. C. Oliveira and Mazzaella laminarioides (Bory) Fredericq, we measured the growth patterns of sporelings built with different numbers of spores, and the magnitude and persistence of the size increments gained by fusions. Then we studied three morphological processes that could help explain the observed growth patterns. Results indicate that in these algae, coalescence is followed by immediate increase in total size of the coalesced individual and that the increment is proportional to the number of individuals fusing. However, the size increments in sporelings of both species do not last > 60 d. Increasing reductions of marginal meristematic cells and increasing abundance of necrotic cells in sporelings built with increasing numbers of initial spores are partial explanations for the above growth patterns. Since sporelings formed by many spores differentiate erect axes earlier and in larger quantities than sporelings formed by one or only a few spores, differentiation, emergence, and growth of erect axes appear as a more likely explanation for the slow radial growth of the multisporic sporelings. Erect axis differentiation involves significant morphological and physiological changes and a shift from radial to axial growth. It is concluded that the growth pattern exhibited by these macroalgae after fusion differs from equivalent processes described for other organisms with the capacity to fuse, such as modular invertebrates.