New role for majors in Atta leafcutter ants

Abstract.  1.  Atta (Hymenoptera: Formicidae) leafcutter ants display the most polymorphic worker caste system in ants, with different sizes specialising in different tasks. The largest workers (majors) have large, powerful mandibles and are mainly associated with colony defence.
2. Majors were observed cutting fallen fruit and this phenomenon was investigated in the field by placing mango fruit near natural Atta laevigata and Atta sexdens colonies in São Paulo State, Brazil.
3. Ants cutting the fruit were significantly heavier (mean = 49.1 mg, SD = 11.1 mg, n = 90) than the ants carrying the fruit back to the nest (mean = 20.9 mg, SD = 9.2 mg, n = 90).
4. Fruit pieces cut by majors were small (mean = 15.9 mg), approximately half the weight of leaf pieces (mean = 28.5 mg) cut and carried by media foragers. It is hypothesised that it is more difficult to cut large pieces from three-dimensional objects, like fruit, compared to two-dimensional objects, like leaves, and that majors, with their longer mandibles, can cut fruit into larger pieces than medias.
5. The study shows both a new role for Atta majors in foraging and a new example of task partitioning in the organisation of foraging.     

Development of an RT-PCR on the Heat Shock Protein 70 Gene for Viability Detection of Pneumocystis carinii f. sp. hominis in Patients with Pneumocystosis and in Air Sample

SUMMARY. To test the viability of Pneumocystis carinii f. sp. hominis , an RT-PCR assay that employs specific primers from the Heat Shock Protein 70 gene was developed. Using this method, the viability of P.c. hominis in bronchoalveolar lavage fluids from patients developing PCP and in the environment of PCP patients was established.     

SENSORY EVALUATION BASED ON VERBAL JUDGMENTS

Studies of the repeatability and the homogeneity of expert panel scores in sensory profiling show that lasting and reliable evaluations of food products are difficult to obtain: strong inter- and intra-individual differences are commonly observed. Our hypothesis is that this variability is due to quantification methods that consist of asking panelists to furnish quantitative values (by attributing a numerical point to perceived intensity) and that using natural language in the form of verbal judgements in a hierarchical tree would allow improving the reliability of sensory evaluations. This hypothesis was tested by comparing a numerical value scale and a specific hierarchical semantic scale that subjects devised themselves prior to the experiment. The products (chocolate dessert creams) were evaluated using each of the two methods. The results show that the capacity to discriminate between products is better when verbal judgements are used. We discuss the advantages of hierarchical semantic scales for sensory profiling.     

SOLNHOFEN-STYLE SOFT-TISSUE PRESERVATION IN A NEW SPECIES OF TURTLE FROM THE CRATO FORMATION (EARLY CRETACEOUS, APTIAN) OF NORTH-EAST BRAZIL

Abstract:  The partial, articulated skeleton of a pleurodiran turtle from the Nova Olinda Member of the Crato Formation (Araripe Basin) of north-east Brazil displays an impression of the outline of the soft tissues surrounding the left hind limb. The external mould of the soft tissue surface preserves only the gross morphology of the limb although the outline of the limb is well defined. It appears to be an external mould of the limb's surface, which formed prior to the decay of the integument. The limb skeleton is mostly fully articulated. This style of preservation is comparable with the mouldic preservation found in such famous fossils as the feathered Archaeopteryx specimens of the Solnhofen limestone. Although soft-tissue preservation is occasionally encountered in the Crato Formation, this is the first documented occurrence of mouldic preservation of body outline reported for this Konservat-Lagerstätten. The new specimen is referred to the pelomedusoid Araripemys and represents a new species, A. arturi sp. nov., which is described here.     

The influence of different spatial‐scale variables on caddisfly assemblages in Flemish lowland streams

1. Patterns in species assemblages are the result of the combined influence of processes acting on different spatial scales. Various studies describe the distribution of macroinvertebrate communities and their relationship with environmental factors at different geographical scales, but only a few of these studies concentrate on Western European lowlands. 2. Using Flanders as representative for the densely populated Western‐European lowlands, the specific aims of this study are: (i) to identify the different trichopteran species assemblages and to characterise them biologically using indicator species; (ii) to determine which environmental gradients most influence the observed species assemblages; and (iii) to analyse the relative importance of different spatial scale variables in constraining the Trichoptera distributions. 3. Assessment of the main environmental gradients suggested that the absence of Trichoptera from certain locations was mainly due to elevated nutrient concentrations and lower oxygen contents, confirming their sensitivity to anthropogenic disturbance. 4. Five Trichoptera species assemblages were distinguished based on Bray–Curtis dissimilarity coefficients. These assemblages did not differ significantly in species richness, but a shift in stream zonation preference was observed. In the ordination analysis 11 variables that were selected using a stepwise model building function manifested themselves as upstream–downstream and size‐related gradients. The Trichoptera assemblages in lowland streams thus appear to follow a longitudinal succession pattern that corresponds with the species‐specific preferences. 5. Partitioning the variance over the different spatial scales indicated that the reach‐scale variables were far more important in explaining the variation in species composition. The study design, which limited the minimum–maximum range of catchment‐scale characteristics, however, may have led to an overestimation of the impact of the local‐scale variables.     

Response of Mediterranean coralline algae to ocean acidification and elevated temperature

The effects of elevated partial pressure of CO₂ ( p CO₂) and temperature, alone and in combination, on survival, calcification and dissolution were investigated in the crustose coralline alga Lithophyllum cabiochae . Algae were maintained in aquaria during 1 year at near-ambient conditions of irradiance, at ambient or elevated temperature (+3 °C) and at ambient [ca. 400 parts per million (ppm)] or elevated p CO₂ (ca. 700 ppm). Algal necroses appeared at the end of summer under elevated temperature first at 700 ppm (60% of the thallus surface) and then at 400 ppm (30%). The death of algae was observed only under elevated temperature and was two- to threefold higher under elevated p CO₂. During the first month of the experiment, net calcification was significantly reduced under elevated p CO₂. At the end of the summer period, net calcification decreased by 50% when both temperature and p CO₂ were elevated while no effect was found under elevated temperature and elevated p CO₂ alone. In autumn and winter, net calcification in healthy algae increased with increasing temperature, independently of the p CO₂ level, while necroses and death in the algal population caused a net dissolution at elevated temperature and p CO₂. The dissolution of dead algal thalli was affected by elevated p CO₂, being two- to fourfold higher than under ambient p CO₂. These results suggest that net dissolution is likely to exceed net calcification in L. cabiochae by the end of this century. This could have major consequences in terms of biodiversity and biogeochemistry in coralligenous communities dominated by these algae.     

Starvation and Cell Wall Formation in the Myxomycete physarum polycephalum

Microplasmodia of the myxomycete physarum polycephalum weregrown in submersed agitated culture. When transferred from vigorouslygrowing cultures to non-nutrient balanced salt solution, theybegan to subdivide approximately 12 hours later and to formcell walls in a manner similar to that previously describedfor ‘aging’ cultures and for the formation of typicalsclerotia.     

A Biolchemical and Cytochemical Study of Peroxidase Activity in Roots of Pisum sativum: I. A COMPARISON OF DAB-PEROXIDASE AND GUAIACOL-PEROXIDASE WITH PARTICULAR EMPHASIS ON THE PROPERTIES OF CELL WALL ACTIVITY

Peroxidase activity in roots of Pisum sativum has been examinedusing both guaiacol and 3,3'-diaminobenzidine (DAB) as hydrogendonors. Biochemically, differences were observed between thetwo donors with respect to the pH optimum (6–9 and 4–0,respectively), and in response to added NaCl (guaiacol-peroxidasewas unaffected while the DAB-peroxidase was markedly inhibited).Both reactions showed highest specific activity in a high speedsupernatant fraction, and, of nine anionic bands demonstratedby gel electrophoresis with DAB, only six were visible withguaiacol. Histochemically, similar staining patterns were observedwith both donors. Cell wall fractions prepared by bead filtration contained 2%and 3.5% of the total peroxidase and acid phosphatase activitiesrespectively. 50% and 27% of these activities were ionicallybound, as indicated by salt treatment In addition, washing withsalt solutions produced a marked stimulation of peroxidase activityat high salt concentrations: this affect was not observed withthe supernatant peroxidase or with cell wall acid phosphatase.Possible functions of cell wall peroxidase are discussed     

A Biochemical and Cytochemical Study of Peroxidase Activity in Roots of Pisum sativum: II. DISTRIBUTION OF ENZYMES IN RELATION TO ROOT DEVELOPMENT

Changes in the specific activity and multiple forms of peroxidasealong the differentiating root of Pisum sativum have been examined.The specific activity of the total homogenate increased steadilyalong the root, although that of the low speed supernatant fractionshowed a fall in the first 20 mm. This finding supports previouscytochemical studies which showed low activity in the meristemand increased cell wall activity in the older regions. Acidphosphatase also increased gradually along the root, althoughphenylalanine ammonia lyase (PAL) showed a peak in the 20–40mm region which corresponded with the first positive stainingfor lignin. When stelar and cortical tissues were compared,peroxidase specific activity was highest in a cortical supernatantfraction while PAL was highest in the stelar tissues. The separationof peroxidase by gel electrophoresis showed the presence ofa number of bands'which varied both along the root and betweenstele and cortex. The results are discussed in relation to thepossible functions of peroxidase and, in particular, to itsproposed role in lignification.