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Ballina-Gomez H.S.,Research Center Cientfica Of Yucatan | Ballina-Gomez H.S.,Conkal Institute of Technology | Iriarte-Vivar S.,Research Center Cientfica Of Yucatan | Iriarte-Vivar S.,National Autonomous University of Mexico | And 2 more authors.
Journal of Tropical Ecology | Year: 2010

Defoliation, often caused by herbivory, is a common cause of biomass loss for plants that can affect current and future growth and reproduction. There are three models that predict contrasting compensatory growth responses of plants to herbivory and resource availability: (1) Growth rate model, (2) Compensatory continuum hypothesis and (3) Limiting resource model. The predictions of these three models were tested on the tree Brosimum alicastrum and the liana Vitis tiliifolia. Seedlings were subjected to three levels of experimental defoliation (0%, 50% and 90% leaf removal) along a light resource gradient (1%, 9% and 65% of full sun). In both species, defoliation significantly increased leaf production rate and relative growth rate of leaf area, but not of biomass. Net assimilation rate was the strongest driver of biomass growth in both species, but leaf area ratio and specific leaf area were also important in B. alicastrum. Compensatory responses of leaf area growth in B. alicastrum were significantly greater in higher than lower light availability, consistent with the compensatory continuum hypothesis predictions, but in contrast to the growth rate model predictions. The limiting resource model offered an explanation for all possible experimental outcomes by directly considering the effects of environmental differences in resource availability. Copyright © 2010 Cambridge University Press.

Quintal-Novelo C.,Research Center Cientfica Of Yucatan | Moo-Puc R.E.,Instituto Mexicano Del Seguro Social | Chale-Dzul J.,Instituto Mexicano Del Seguro Social | Caceres-Farfan M.,Research Center Cientfica Of Yucatan | And 2 more authors.
Natural Product Research | Year: 2013

A phytochemical investigation of the stem bark of Diospyros cuneata (Ebenaceae) together with in vitro cytotoxic evaluation of the pure compounds in four human cancer cell lines KB, Hep-2, HeLa and SiHa led to the isolation of plumbagin, elliptinone, lupeol, atraric acid methyl ester, maritinone, betulin and betulinaldehyde. The structural determination of the compounds was established by nuclearmagnetic resonance, electron ionisation mass spectrometric analysis as well as comparison with data from the literature. Plumbagin exhibited a potent cytotoxic activity (CC50 1-4 3.56 mgmL1) against KB cell lines whereas maritinone displayed cytotoxic activity against Hep-2 (CC50 1-4 17.30 mgmL1), cervical cancer (CC50 1-4 21.10 mgmL1) and the KB cell lines (CC50 1-4 20.30 mgmL1). This is the first report on a phytochemical and biological evaluation of D. cuneata. . © 2013 Taylor &Francis.

Stefano R.D.D.,Research Center Cientfica Of Yucatan | Fernandez-Concha G.C.,Research Center Cientfica Of Yucatan | Can-Itza L.L.,Research Center Cientfica Of Yucatan | Lavin M.,Montana State University
Systematic Botany | Year: 2010

A new combination, Coursetia greenmanii (Leguminosae, Papilinioideae, tribe Robinieae), is proposed because analysis of nucleotide sequence data from the nuclear ribosomal internal transcribed spacer region resolves a clade that is phenotypically distinct and ecologically and geographically centered in lowland seasonally dry tropical vegetation of the Yucatan Peninsula region. The well supported monophyly of the ribosomal sequences sampled from Coursetia greenmanii suggests that this species has had a long history independent of its close relatives. Coalescence of intraspecific samples of ribosomal sequences from this geographically confined species is strongly suggestive of an evolutionary persistent small effective population size. This is the general case for species of Coursetia and related genera of the tribe Robinieae. Coalescence of nuclear ribosomal sequences sampled from geographically restricted species in this group further suggests that evolutionary persistence could be the result of high levels of dispersal limitation in seasonally dry Neotropical vegetation that is rich in cacti and other succulent species. This is the ecological setting to which Robinieae shows phylogenetic niche conservatism. © Copyright 2010 by the American Society of Plant Taxonomists.

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