In vivo endocrine effects of naphthenic acids in fish

Oil pollution from various sources, including exploration, production and transportation, is a growing global concern. The highest toxicity of hydrocarbon pollutants is associated with the water-soluble phase compounds, including naphthenic acids, a known component found in all hydrocarbon deposits. Recently, naphthenic acids (NAs) have shown estrogenic and anti-androgenic effects in vitro. For this reason we investigated the potential effects of two commercial mixtures of naphthenic acids on fish in vivo, using the three-spined stickleback (Gasterosteus aculeatus) as a model species.     

Ambivalence and conservation behaviour: An exploratory study on the recycling of metal cans

As resource conservation is an imperative for sustainable development, it is crucial to achieve a deeper understanding of the factors involved in people's decisions to recycle. This is even more so because the level of environmental concern is usually higher than the level of ecological behaviours. In this paper we take this fact as indicating that decision-making regarding conservation behaviours happens in the context of an internal debate where contradictory ideas are weighed up and the possibility of ambivalence arises. The main aim of this paper is therefore to explore how contradiction and ambivalence impact upon the attitudes, intentions and pro-ecological behaviours of the private sphere. The paper focuses specifically on the separation and deposition of metal cans, and compares the predictive capacity of beliefs, attitudes and intentions for two groups of respondents – one with a high and another with a low level of ambivalence, as assessed with a direct measure. The role of personal identity and the influence of structural constraints are also explored. Results demonstrate a clear moderating effect of experienced ambivalence, and show how beliefs, particularly negative ones, present a higher predictive capacity of the attitude in the high-ambivalence group, and personal identity plays a relevant role in predicting behaviour in both groups. We discuss the importance of pursuing the study of ambivalence when analysing decision-making in the conservation area.     

Denaturing high-performance liquid chromatography (DHPLC)-based prenatal diagnosis for tuberous sclerosis

Tuberous sclerosis (TSC) is a frequent autosomal-dominant condition (affecting 1 in 6000 individuals) caused by various mutations in either the hamartin (TSC1) or the tuberin gene (TSC2). This allelic and non-allelic heterogeneity makes genetic counseling and prenatal diagnosis difficult, especially as a significant proportion of TSC cases are due to de novo mutations. For this reason the identification of the disease causing mutation is mandatory for accurate counseling, yet current mutation detection methods such as single-strand conformation polymorphism (SSCP) or denaturing gradient gel electrophoresis (DGGE) are labor intensive with limited detection efficiency. Denaturing high-performance liquid chromatography (DHPLC) is a high-throughput, semi-automated mutation detection system with a reported mutation detection rate close to 100% for PCR fragments of up to 800 bp. We used a recently described DHPLC assay allowing the efficient detection of mutations in TSC1 to analyze the DNA extracted from a chorion villus sample in order to perform a prenatal diagnosis for TSC. The fetus was found not to have inherited the deleterious mutation and the DHPLC diagnosis was confirmed by haplotype analysis. This represents the first DHPLC-based prenatal diagnosis of a genetic disease. Copyright © 2001 John Wiley & Sons, Ltd.     

Cost of parental care in the woodroach Cryptocercus punctulatus Scudder (Dictyoptera: Cryptocercidae)

Summary The objective of this study was to measure the effect of parental care on the reproductive capabilities and survival of adult Cryptocercus punctulatus Scudder. Brood removal studies show that the long term parental care exhibited by this woodroach can exact a cost in terms of future reproduction by delaying a second reproductive episode. If C. punctulatus is used as a model of the ancestral state of the termites, changes in responsibility for care giving behavior can account for all the higher components of eusociality (overlap of worker generations, brood care by workers, non-reproductive castes) by shifting the cost of parental care from the adults to the oldest offspring.     

Interactions between wave action and grazing control the distribution of intertidal macroalgae

Canopy-forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave-induced forces and grazing for the recruitment and survival of the canopy-forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long-term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7-8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or prune Fucus spp. larger than approximately 10 cm, while dislodgment was highly unlikely on the landward side for all sizes. Experimental transplantation of Fucus spp. supported the biomechanical analysis but also suggested that mechanical abrasion may further limit survival in wave-exposed locations. Experimental removal of the limpet Patella vulgata, which was the principal grazer at this site, resulted in recruitment of Fucus spp. on the seaward side. We present a model of limpet grazing that indicates that limpet densities >5-20 individuals/m2 provide a proximate mechanism preventing establishment of Fucus spp., whereas wave action >2 m/s reduces persistence through dislodgment and battering. In a conceptual model we further propose that recruitment and survival of juvenile Fucus spp. are controlled indirectly by wave exposure through higher limpet densities at exposed locations. This model predicts that climate change, and in particular an increased frequency of storm events in the northeast Atlantic, will restrict fucoids to more sheltered locations.