Seagrass-bivalve facilitative interactions: Trait-mediated effects along an environmental gradient

While there is substantial evidence for facilitation, the effects of such factors as stress and species identity on positive interactions remain controversial. At two coastal dune sites, I tested the hypotheses that facilitative interactions increase with increasing stress and disturbance along an environmental gradient and that facilitative interactions are stronger among heterospecific than among conspecific individuals. I transplanted Uniola paniculata and Iva imbricata plants into plots along with four conspecific neighbors, four heterospecific neighbors, or no neighbors across an environmental gradient. Neighbors increased target plant survival, suggesting facilitation, but biomass of targets was reduced by the presence of neighbors, suggesting competition. Unexpectedly, competition was greatest in the purportedly most stressful and disturbed zone. In this study, the outcome of neighbor interactions differed for biomass and survival and depended on position along the environmental gradient, but was independent of neighbor identity.Key words: competition, disturbance, facilitation, Iva imbricata, stress, Uniola paniculata.

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Phytochrome-mediated effects on extracellular peroxidase activity, lignin content and bending resistance in etiolated Vicia faba epicotyls

Physiologia Plantarum ◽

10.1034/j.1399-3054.1994.920403.x ◽

1994 ◽

Vol 92 (4) ◽

pp. 555-562 ◽

Cited By ~ 1

Author(s):

Jorge J. Casal ◽

R. Alejandra Mella ◽

Carlos L. Ballare ◽

Sara Maldonado

Keyword(s):

Vicia Faba ◽

Peroxidase Activity ◽

Lignin Content ◽

Extracellular Peroxidase ◽

Mediated Effects ◽

Bending Resistance

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Protective Effect of Vitamin E on Immune Triggered, Granulocyte Mediated Endothelial Injury

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661027 ◽

1984 ◽

Vol 51 (01) ◽

pp. 089-092 ◽

Cited By ~ 24

Author(s):

M A Boogaerts ◽

J Van de Broeck ◽

H Deckmyn ◽

C Roelant ◽

J Vermylen ◽

...

Keyword(s):

Vitamin E ◽

Protective Effect ◽

Umbilical Vein ◽

Endothelial Damage ◽

Endothelial Injury ◽

Mediated Effects ◽

Anti Oxidant ◽

Endothelial Cell Cultures ◽

Vitro Model

SummaryThe effect of alfa-tocopherol on the cell-cell interactions at the vessel wall were studied, using an in vitro model of human umbilical vein endothelial cell cultures (HUEC). Immune triggered granulocytes (PMN) will adhere to and damage HUEC and platelets enhance this PMN mediated endothelial injury. When HUEC are cultured in the presence of vitamin E, 51Cr-leakage induced by complement stimulated PMN is significantly decreased and the enhanced cytotoxicity by platelets is completely abolished (p <0.001).The inhibition of PMN induced endothelial injury is directly correlated to a diminished adherence of PMN to vitamin E- cultured HUEC (p <0.001), which may be mediated by an increase of both basal and stimulated endogenous prostacyclin (PGI2) from alfa-tocopherol-treated HUEC (p <0.025). The vitamin E-effect is abolished by incubation of HUEC with the irreversible cyclo-oxygenase inhibitor, acetylsalicylic acid, but the addition of exogenous PGI2 could not reproduce the vitamin E-mediated effects.We conclude that vitamin E exerts a protective effect on immune triggered endothelial damage, partly by increasing the endogenous anti-oxidant potential, partly by modulating intrinsic endothelial prostaglandin production. The failure to reproduce vitamin E-protection by exogenously added PGI2 may suggest additional, not yet elucidated vitamin E-effects on endothelial metabolism.

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