Cytochemical Study on the Dormancy-imposing Endosperm of Cercis siliquastrum

Cytochemical observations indicate the occurrence of leucoanthocyanidinsin the protein bodies of Cercis siliquastrum endosperm; theendosperm cell walls give a positive Mayer's test, indicatingmucopolysac-charides. These results are discussed in relationto the endosperm-imposed dormancy of the seed. Cercis siliquastrum, endosperm-imposed dormancy, leucoanthocyanidins, mucopolysac-charides     

Action Mechanisms of the Secondary Metabolite Euplotin C: Signaling and Functional Role in Euplotes

ABSTRACT. Among secondary metabolites, the acetylated hemiacetal sesquiterpene euplotin C has been isolated from the marine, ciliated protist Euplotes crassus, and provides an effective mechanism for reducing populations of potential competitors through its cytotoxic properties. However, intracellular signaling mechanisms and their functional correlates mediating the ecological role of euplotin C are largely unknown. We report here that, in E. vannus (an Euplotes morphospecies that does not produce euplotin C and shares with E. crasssus the same interstitial habitat), euplotin C rapidly increases the intracellular concentration of both Ca²⁺ and Na⁺, suggesting a generalized effect of this metabolite on cation transport systems. In addition, euplotin C does not induce oxidative stress, but modulates the electrical properties of E. vannus through an increase of the amplitude of graded action potentials. These events parallel the disassembling of the ciliary structures, the inhibition of cell motility, the occurrence of aberrant cytoplasmic vacuoles, and the rapid inhibition of phagocytic activity. Euplotin C also increases lysosomal pH and decreases lysosomal membrane stability of E. vannus. These results suggest that euplotin C exerts a marked disruption of those homeostatic mechanisms whose efficiency represents the essential prerequisite to face the challenges of the interstitial environment.     

Behaviour and stress response during capture and handling of the red-billed chough Pyrrhocorax pyrrhocorax (Aves: Corvidae)

We studied the effect of capture and handling on free-living red-billed choughs Pyrrhocorax pyrrhocorax . We analysed the association between bird behavioural response and individual health, breeding status, sex, and age. Active responses (aggression towards the ringer, screaming) were more common in the breeding period, and in individuals with a high heterophils to lymphocytes ratio, indicating poor physiological condition and/or high chronic stress. Adults were more aggressive than juveniles and yearlings, and females were more aggressive than males. Sex, age, and condition differences were also recorded in the spectrotemporal output of distress calls. Birds with a screaming/active response appeared to be more stress-susceptible than passive and silent individuals, and this response was stronger during the energy demanding period of reproduction. The results obtained suggest that the response of the red-billed chough during capture might primarily reflect stress-susceptibility, although a number of potential alternative explanations are discussed.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 846–855.