Defensive role of allelopathic secondary compounds in plants I: testing two independent general hypotheses

This study tests two general and independent hypotheses with the basic assumption that phytoactive secondary compounds produced by plants evolved primarily as plant defences against competitor plant species. The first hypothesis is that the production and main way of release of phytoactive compounds reflect an adaptive response to climatic conditions. Thus, higher phytoactivity by volatile compounds prevails in plants of hot, dry environments, whereas higher phytoactivity by water-soluble compounds is preponderant in plants from wetter environments. The second hypothesis is that synergy between plant phytoactive compounds is widespread, due to the resulting higher energy efficiency and economy of resources. The first hypothesis was tested on germination and early growth of cucumber treated with either water extracts or volatiles from leaves or vegetative shoot tops of four Mediterranean-type shrubs. The second hypothesis was tested on germination of subterranean clover treated with either water extracts of leaves or vegetative shoot tops of one tree and of three Mediterranean-type shrubs or with each of the three fractions obtained from water extracts. Our data do not support either hypotheses. We found no evidence for higher phytoactivity in volatile compounds released by plants that thrive in hot, dry Mediterranean-type environments. We also found no evidence for the predominance of synergy among the constituents of fractions. To the contrary, we found either antagonism or no interaction of effects among allelopathic compounds.

Portuguese Version of the Suicidal Behaviors Questionnaire-Revised: Validation Data and the Establishment of a Cut-Score for Screening Purposes

The aim of the present study is to provide validation data regarding the Portuguese version of the Suicidal Behaviors Questionnaire Revised in nonclinical individuals. Two studies were undertaken with two different nonclinical samples in order to demonstrate reliability, concurrent, predictive, and construct validity, and in order to establish an appropriate cut-score for nonclinical individuals. A sample of 810 community adults participated in Study 1. Results from this study provided information regarding scale internal consistency, exploratory and confirmatory factor analysis, and concurrent validity. Receiver operating characteristic curve analysis established a cut-off score to be used for screening purposes with nonclinical individuals. A sample of 440 young adults participated in Study 2, which demonstrated scale score internal consistency and 5-month predictive validity. Further, 5-month test-retest reliability was also evaluated and the correlations of SBQ-R scale scores with two other measures that assess constructs related to suicidality, depression and psychache, were also performed. In addition, confirmatory factor analysis was undertaken to demonstrate the robustness of the result obtained in Study 1. Overall, findings supported the psychometric appropriateness of the Portuguese Suicidal Behaviors Questionnaire-Revise