Are behavioural responses to predation cues linked across life cycle stages?

1. Prey organisms can perceive cues to predation hazard and adopt low‐risk behaviours to increase survival. Animals with complex life cycles, such as insects, can exhibit such anti‐predatory behaviours in multiple life stages. 2. Cues to predation risk may induce ovipositing females to choose habitats with low predation risk. Cues to predation risk may also induce larvae to adopt facultative behaviours that reduce risk of predation. 3. One hypothesis postulates that anti‐predation behaviours across adult and larval stages may be negatively associated because selection for effective anti‐predator behaviour in one stage leads to reduced selection for avoidance of predators in other stages. An alternative hypothesis suggests that selection by predation favours multi‐component defences, with both avoidance of oviposition and facultative adoption of low‐risk behaviours by larvae. 4. Laboratory and field experiments were used to determine whether defensive responses of adult and larval mosquitoes are positively or negatively associated. The study tested effects of waterborne cues from predatory Toxorhynchites theobaldi on oviposition choices and larval behaviours of three of its common prey: Culex mollis, Limatus durhamii and Aedes albopictus. 5. Culex mollis shows strong anti‐predator responses in both life stages, consistent with the hypothesis of a multi‐component behavioural defence. The other two species showed no detectable responses to waterborne predator cues in either adult or larval stages. Larvae of these unresponsive species were significantly more vulnerable to this predator than was C. mollis. 6. For these mosquitoes, species appear either to have been selected for multi‐component defences against predation or to act in ways that could be called predator‐naïve.     

Associations between polymorphisms in five inflammation‐related genes and cognitive ability in older persons

Several studies have found associations between inflammatory biomarker levels and cognitive ability. This study tested the relationship between polymorphisms in genes that are associated with or encode the biomarkers and cognitive ability and estimated lifetime cognitive change. Data came from the aspirin for asymptomatic atherosclerosis trial (n = 2091, mean age = 67.2 years ). Twelve single nucleotide polymorphisms (SNPs) were genotyped from five genes (IL‐1α, IL‐1β, IL‐6, HNF‐1A and F13A1). Cognition was assessed via administration of a five‐test battery of psychometric tests, which were used to derive a general intelligence factor, g. A vocabulary‐based cognitive test was also administered and adjusted for in the analysis to enable an estimation of lifetime cognitive change. Age‐ and sex‐adjusted analyses yielded one weakly significant association between the IL‐1α rs2856838 SNP and a measure of mental flexibility/processing speed (P = 0.044). Adjustment for the vocabulary‐based scores resulted in a single, significant association between the IL‐1α rs3783546 SNP and a measure of processing speed (P = 0.048). There is little evidence to suggest an association between SNPs in the inflammation‐related genes IL‐1α, IL‐1β, IL‐6, TCF‐1 and F13A1 and cognition in an elderly population of community‐dwelling Scottish citizens.     

Effects of sediment deposition on the seaweed Sargassum on a fringing coral reef

 Coral reef degradation may involve shifts from coral to algal dominance and may be caused in part by increased sediment loads. Inshore fringing reef flats in the central Great Barrier Reef region are often subjected to periods of high sedimentation and are often dominated by macroalgae such as Sargassum. Experiments reported here examine the impacts of sediments on the recruitment, growth, survival, degeneration and vegetative regeneration of Sargassum microphyllum on a fringing coral reef flat in the central Great Barrier Reef. Comparison of three levels of sediment deposition (experimental addition, control (ambient condition) and experimental removal) showed that increased amounts of sediment significantly decreased rates of recruitment, growth, survival and vegetative regeneration, but not degeneration of S. microphyllum. In addition, the regenerative ability of S. microphyllum thalli with short, persistent erect branches (untreated) was compared with that of thalli experimentally cut back to the holdfast. This experimental damage significantly reduced regeneration. Accepted: 6 October 1997     

Studies on plant growth-regulating substances LIII. The conversion of certain substituted ethylamines to active growth substances in plants

A number of substituted phenylethylamines have been synthesised and their plant growth-regulating activities, in standard wheat and pea tests, have been determined and compared with those of related substituted phenoxyethylamines, phenylacetic acids and phenoxyacetic acids. The effects of applying the most active amines to various plant species are described and the results are considered in relation to the possible ability of the plant to convert the amine into the physiological active acetic acid derivative.     

Studies on plant growth-regulating substances. LIV. Factors affecting the production of active growth substances from structurally related amines in plants

A diamine oxidase enzyme has been isolated from pea epicotyls and purified. The in vitro rates at which a number of amines, structurally related to plant growth substances, are oxidised by this enzyme have been measured. These rates when considered together with the growth regulating activity of the acid ultimately produced, enable an assessment of the activity of the amine as a hormone-type herbicide to be made.