Bioaccumulation of Lead, Calcium and Strontium and their Relationships in the Octopus Octopus vulgaris

Octopuses (Octopus vulgaris) landed from commercial fishing were sampled and the concentrations of lead, calcium and strontium, in digestive gland, branchial heart, gills, mantle and arms, were determined using PIXE (particle-induced X-ray emission). Lead was detected in all tissues, although not in samples from all animals analysed. Female octopuses accumulated more lead in digestive gland than did males. The digestive gland index, an indicator of nutritional status, showed a negative correlation with lead concentration in both sexes. There were positive correlations between the concentration of lead and those of calcium and strontium in digestive gland and a negative correlation between lead and calcium in branchial heart tissue. Concentrations of calcium in arms were lower in autumn and spring than in winter and summer. Lead content increased with increasing body weight and mantle length so we can conclude that lead continues to accumulate during the animal’s life. Concentrations of lead in two samples were higher than the maximum legally permitted concentration of lead in food.     

Residual patterns of alkyl polyoxyethylene surfactant droplets after water evaporation

Using a nonionic, alkyl polyoxyethylene surfactant (X-77) in aqueous solutions, sessile droplet spreading, pinning, evaporation, contraction, and post-evaporation deposits are characterized. X-77 is widely used in the agricultural field as a spreader/adherent, intended to optimize pathenogenic agent coverage. Using a single droplet size under monitored temperature conditions, we control humidity, substrate hydrophobicity, and surfactant concentration to mimic varying agricultural conditions. For hydrophilic surfaces, the droplet spreads, reaching and retaining a maximum, stationary size. At this stage, a ring accretion occurs at the maximum spread diameter. During the final stage, the water film retracts, resulting in deposition of small islands of surfactant residue inside the ring. At lower concentrations of surfactant, we discover ring formations that break-up into "ring islands" at late-stage evaporation, accompanied by a distribution of the smaller islands in the interior portion of the substrate contact area. These are promoted by higher relative humidity. At higher concentrations, only a solid ring of surfactant remains, post-evaporation. Increasing surfactant concentration tends to increase the mean of the interior island size and to broaden the overall island size distribution. On sufficiently hydrophobic surfaces, surfactant-laden droplets do not evidence pinning, ring formations, or post-evaporation interior islands. Interestingly, lower humidity increases spreading at higher surfactant concentrations. Such pattern formations of surfactant deposit are reported for the first time and are of significance in projecting how surfactants such as X-77 distribute pesticides or other chemicals on leaf surfaces.     

Parasitoids as selective agents in the symbiosis between lycaenid butterfly larvae and ants

The larvae of Glaucopsyche lygdamus (Lepidoptera: Lycaenidae) secrete substances that attract ants. In two field sites in Colorado, tending ants protect caterpillars of G. lygdamus from attack by braconid and tachinid parasitoids. This protection may have been an important feature in the evolution of the association between lycaenid larvae and ants.     

The effect of stocking rate and calving date on grass production,utilization and nutritive value of the sward during the grazing season

A 2‐year whole‐farm system study compared the accumulation, utilization and nutritive value of grass in spring‐calving grass‐based systems differing in stocking rate (SR) and calving date (CD). Six treatments (systems) were compared over two complete grazing seasons. Stocking rates used in the study were low (2·5 cows ha^?1), medium (2·9 cows ha^?1) and high (3·3 cows ha^?1), respectively, and mean CDs were 12 February (early) and 25 February (late). Each system had its own farmlet of eighteen paddocks and one herd that remained on the same farmlet area for the duration of the study. Stocking rate had a small effect on total herbage accumulation (11 860 kg DM ha^?1 year^?1), but had no effect on total herbage utilization (11 700 kg DM ha^?1 year^?1). Milk and milk solids (MS; fat + protein) production per ha increased by 2580 and 196 kg ha^?1 as SR increased from 2·5 to 3·3 cows ha^?1. Milk production per ha and net herbage accumulation and utilization were unaffected by CD. Winter feed production was reduced as SR increased. Increased SR, associated with increased grazing severity, resulted in swards of increased leaf content and nutritive value. The results indicate that, although associated with increased milk production per ha, grazed grass utilization and improved sward nutritive value, the potential benefits of increased SR on Irish dairy farms can only be realized if the average level of herbage production and utilization is increased.     

Effects of in vitro brevetoxin exposure on apoptosis and cellular metabolism in a leukemic T cell line (Jurkat)

Harmful algal blooms (HABs) of the toxic dinoflagellate, Karenia brevis, produce red tide toxins, or brevetoxins. Significant health effects associated with red tide toxin exposure have been reported in sea life and in humans, with brevetoxins documented within immune cells from many species. The objective of this research was to investigate potential immunotoxic effects of brevetoxins using a leukemic T cell line (Jurkat) as an in vitro model system. Viability, cell proliferation, and apoptosis assays were conducted using brevetoxin congeners PbTx-2, PbTx-3, and PbTx-6. The effects of in vitro brevetoxin exposure on cell viability and cellular metabolism or proliferation were determined using trypan blue and MTT (1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan), respectively. Using MTT, cellular metabolic activity was decreased in Jurkat cells exposed to 5 – 10 μg/ml PbTx-2 or PbTx-6. After 3 h, no significant effects on cell viability were observed with any toxin congener in concentrations up to 10 μg/ml. Viability decreased dramatically after 24 h in cells treated with PbTx-2 or -6. Apoptosis, as measured by caspase-3 activity, was significantly increased in cells exposed to PbTx-2 or PbTx-6. In summary, brevetoxin congeners varied in effects on Jurkat cells, with PbTx-2 and PbTx-6 eliciting greater cellular effects compared to PbTx-3.