The communal crop: modulation of sucrose response thresholds of pre-foraging honey bees with incoming nectar quality

We examined whether the quality (concentration) of incoming sucrose solutions returned by foraging honey bees affected the response thresholds of pre-foraging members of the colony. Six pairs of colonies were given ad libitum access to sucrose solution feeders. A colony from each pair was switched from 20–50% sugar concentration feeders while the other continued to have access to 20% sucrose feeders. Proboscis extension response (PER) scores to an increasing series of sucrose concentrations were significantly higher in pre-foragers of colonies foraging on 20% sucrose throughout compared to pre-foragers in colonies where foraging was switched to 50% sucrose. Although all colonies had honey stores, the concentration of sugar solution in non-foraging bees crops were significantly lower in bees from colonies foraging on 20% sucrose compared to those from colonies foraging on 50% sucrose. Because response thresholds to sugar of young bees were modulated by the concentration of sucrose solution returned to colonies, we repeated the 2000 study of Pankiw and Page that potentially confounded baseline response thresholds with modulated scores due to experience in the colony. Here, we examined PER scores to sucrose in bees within 6 h of emergence, prior to feeding experience, and their forage choice 2 to 3 weeks later. Pollen foragers had higher PER scores as newly emerged bees compared to bees that eventually became nectar foragers. These results confirm those of the 2000 study by Pankiw and Page. Combined, these experiments demonstrate that variation in pre-forager sucrose response thresholds are established prior to emerging as adults but may be modulated by incoming resources later on. Whether this modulation has long-term effects on foraging behavior is unknown but modulation has short-term effects and the potential to act as a means of communication among all bees in the colony.Communicated by M. Giurfa     

Patterns of Diversity of Neotropical Squamate Reptile Species with Emphasis on the Brazilian Amazon and the Conservation Potential of Indigenous Reserves

We present new distibutional data for squamate reptiles (amphisbaenians, lizards, and snakes) from several Neotropical sites and estimate species (alpha) diversity at each site. Species compositions at all localities were used to estimate similarity in species richness within and between each of the major regions sampled: Central American lowland forests, Amazonia, and South American dryland forests. We used these estimates to derive maps summarizing overall regional patterns (beta diversity) of squamate richness. Both groups clearly reveal distinct faunal divisions among the three regions. Within Amazonia, lizards and snakes show a clear division in species composition between a "western edge" cluster of sites adjacent to eastern Andean slopes and all other localities in the central and eastern regions. Within this east-central block of sites, a further division is evident between localities north and south of the main Amazon River channel. These general regions of squamate similarity were qualitatively assessed in Brazil's portion of Amazonia within the context of the distribution of all state, federal, and Indian lands that are in principle afforded some level of protection and therefore offer potential for biodiversity conservation. We assess the potential for biodiversity conservation relative to the size of reserves needed to sustain populations of 500 individuals of the three largest species of snakes and to the distribution of potential conservation areas relative to the regional patterns of diversity identified by the statistical analysis. We conclude that the sizes and distributions of reserves are adequate to sustain viable populations of squamates if these areas can be counted on to play a major role in biodiversity conservation.     

Ammonia excretion by the benthic estuarine shrimp Crangon franciscorum (Crustacea: Crangonidae) in relation to diet

Ammonia excretion of individual Crangon franciscorum Stimpson was monitored in response to ingestion of single meals. The three experimental diets were tubificids, mysids and fish. Ammonia excretion was also monitored for individual shrimp which had been starved. The rate of ammonia excretion was higher for fed than for starved individuals in all cases. Ammonia excretion rates were higher for shrimp which were fed tubificids than those fed the other diets. The rate of excretion was influenced by both weight of the individual and the amount ingested of each diet. Ammonia excretion was influenced by dietary factors other than nitrogen content of the diet or the quantity ingested. The data suggest that field estimates of ammonia excretion based on the excretion rates of starved animals may be underestimates. The recent feeding history of an organism influences the rate of ammonia excretion as well as the relationship between the rate of excretion and weight.     

Flue gas desulfurization by-products additions to acid soil: alfalfa productivity and environmental quality

Flue gas desulfurization (FGD) by-products are created when coal is burned and SO2 is removed from the flue gases. These FGD by-products are often alkaline and contain many plant nutrients. Land application of FGD by-products is encouraged but little information is available related to plant responses and environmental impacts concerning such use. Agricultural lime (ag-lime) and several new types of FGD by-products which contain either vermiculite or perlite were applied at 0, 0.5, 1.0, and 2.0 times the soil's lime requirement (LR) rate to an acidic soil (Wooster silt loam). The highest FGD by-products application rate was equivalent to 75.2 Mg ha(-1). Growth of alfalfa (Medicago sativa L.) was significantly increased compared to the untreated control in the second year after treatment with yields for the 1 x LR rate of FGD approximately 7-8 times greater compared to the untreated control and 30% greater than for the commercial ag-lime. Concentrations of Mo in alfalfa were significantly increased by FGD by-products application, compared to the untreated control, while compared to the ag-lime treatment, concentrations of B increased and Ba decreased. No soil contamination problems were observed, even at the 2xLR rate, indicating these materials can be safely applied to agricultural soils.     

Leaf pack breakdown and macroinvertebrate colonization: bioassessment tools for a high-altitude regulated system?

Leaf pack processing and invertebrate colonization for bioassessment of metals pollution in a stream also impacted by a dam were examined. Differences in leaf breakdown rates at sites upstream and downstream of a metals point source were not detected. However, multivariate and logistic regression techniques indicated there were differences in aquatic macroinvertebrate assemblages that colonized leaf packs above and below the metal inflow. Development of a logistic regression model allowed for prediction of leaf pack location from indicator taxa in the leaf pack invertebrate community. Collector-gatherers, rather than shredders, were the most important predictors of whether leaf packs were located above or below the metal inflow, and were perhaps related to algae growing on leaf packs and/or fine particulate organic matter quality. Biotic structure, in this study, provided more information for evaluating pollution impacts than did measurement of leaf breakdown rates.     

Urban photochemical pollution in the Iberian Peninsula: Lisbon and Barcelona airsheds

Numerical simulations with photochemical transport models were independently performed for two domains situated in the Iberian Peninsula covering the Lisbon and Barcelona airsheds. Although the days chosen for simulation of the two cities are not the same, the synoptic situations in both cases, known as typical summertime situations, were similar, which allowed the development of typical mesoscale circulations, such as sea breezes and mountain and valley winds dominated by the Azores anticyclone. Emission inventories for the two areas were developed. The O3 concentrations recorded in both cities have a similar level. Nevertheless, O(x) values in Barcelona are higher than in Lisbon, which may, at a first glance, indicate an apparently more oxidant atmosphere in Barcelona. Photochemical modeling for the two cities has shown that the behavior of the circulatory patterns in both urban areas is rather different, which mainly has to do with the different strengths of the sea breeze and the topography, inducing an important offshore vertical layered dimension of pollutant transport in Barcelona versus an important inland horizontal transport in Lisbon.     

Photocatalytic detoxification of cyanide and metal cyano-species from precious-metal mill effluents

Photochemically-induced detoxification of various cyanide species from a selected precious-metal mills tailings was investigated in detail. The studies were conducted in the presence or absence of a titanium (IV) oxide semiconductor photocatalyst utilizing simulated sunlight as the irradiation source. It was established that the cyanide ion (both free and complexed) was photocatalytically oxidized to nitrate via cyanate and nitrite. In addition iron, copper, zinc, mercury and arsenic were stabilized as precipitates. The results obtained may have ramifications for the possible use of solar energy for the efficient treatment of large quantities of precious-metal mill-tailing wastes that contain various cyano-species.     

Prenatal diagnosis of zellweger's syndrome by chorionic villus sampling-and a caveat

At 7·5 weeks gestation, two small chorionic villous biopsies were obtained from a woman at risk for Zellweger's cerebro-hepato-renal syndrome, and were separately established in culture. After 3 weeks, dihydroxyacetone phosphate acyltransferase (DHAP-AT) activity was measured in both cultures. The enzyme was markedly deficient in one cell strain and this was subsequently shown to have a male karyotype. However, the second culture had normal enzyme activity and a female karyotype. The pregnancy was terminated at 11·5 weeks gestation, and follow-up studies on fetal tissues confirmed a male fetus with markedly deficient DHAP-AT activity.