Polycyclic aromatic hydrocarbons storage by Fusarium solani in intracellular lipid vesicles

Accumulation and elimination of polycyclic aromatic hydrocarbons (PAHs) were studied in the fungus Fusarium solani. When the fungus was grown on a synthetic medium containing benzo[a]pyrene, hyphae of F. solani contained numerous lipid vesicles which could be stained by the lipid-specific dyes: Sudan III and Rhodamine B. The fluorescence produced by Rhodamine B and PAH benzo[a]pyrene were at the same locations in the fungal hyphae, indicating that F. solani stored PAH in pre-existing lipid vesicles. A passive temperature-independent process is involved in the benzo[a]pyrene uptake and storage. Sodium azide, a cytochrome c oxidation inhibitor, and the two cytoskeleton inhibitors colchicine and cytochalasin did not prevent the transport and accumulation of PAH in lipid vesicles of F. solani hyphae. F. solani degraded a large range of PAHs at different rates. PAH intracellular storage in lipid vesicles was not necessarily accompanied by degradation and was common to numerous other fungi.     

Methane oxidation in a landfill cover with capillary barrier

The methane oxidation potential of a landfill cover with capillary barrier was investigated in an experimental plant (4.8 m x 0.8 m x 2.1m). The cover soil consisted of two layers, a mixture of compost plus sand (0.3 m) over a layer of loamy sand (0.9 m). Four different climatic conditions (summer, winter, spring and fall) were simulated. In and outgoing fluxes were measured. Gas composition, temperature, humidity, matrix potential and gas pressure were monitored in two profiles. CH4 oxidation rate within the investigated top cover ranged from 98% to 57%. The minimum was observed for a short time after irrigation. Temperature distribution, gas concentration profiles and lab-scaled batch experiments indicate that before irrigation the highest oxidising activity took place in a depth of about 30 cm. After irrigation the oxidising horizon seemed to migrate upwards since methanotrophic bacteria develop better there due to an adequate supply with oxygen. It can be assumed that the absence of oxygen is one of the most important limiting factors for the CH4 oxidation process. Abrupt cross-overs between horizons of different soil material may lead to zones of increased water saturation and decreased soil respiration.     

Whole-body 3D kinematics of bird take-off: key role of the legs to propel the trunk

Previous studies showed that birds primarily use their hindlimbs to propel themselves into the air in order to take-off. Yet, it remains unclear how the different parts of their musculoskeletal system move to produce the necessary acceleration. To quantify the relative motions of the bones during the terrestrial phase of take-off, we used biplanar fluoroscopy in two species of birds, diamond dove (Geopelia cuneata) and zebra finch (Taeniopygia guttata). We obtained a detailed 3D kinematics analysis of the head, the trunk and the three long bones of the left leg. We found that the entire body assisted the production of the needed forces to take-off, during two distinct but complementary phases. The first one, a relatively slow preparatory phase, started with a movement of the head and an alignment of the different groups of bones with the future take-off direction. It was associated with a pitch down of the trunk and a flexion of the ankle, of the hip and, to a lesser extent, of the knee. This crouching movement could contribute to the loading of the leg muscles and store elastic energy that could be released in the propulsive phase of take-off, during the extension of the leg joints. Combined with the fact that the head, together with the trunk, produced a forward momentum, the entire body assisted the production of the needed forces to take-off. The second phase was faster with mostly horizontal forward and vertical upward translation motions, synchronous to an extension of the entire lower articulated musculoskeletal system. It led to the propulsion of the bird in the air with a fundamental role of the hip and ankle joints to move the trunk upward and forward. Take-off kinematics were similar in both studied species, with a more pronounced crouching movement in diamond dove, which can be related to a large body mass compared to zebra finch.     

Gastral drumming: a nest-based food-recruitment signal in a social wasp

Many social insect species produce signals that either recruit foragers to a specific food source or simply activate more nestmates to become foragers. Both are means of enhancing resource exploitation by increasing the number of individuals devoted to gathering profitable resources. Gastral drumming (GD) has been documented in several species of yellowjackets and hornets (Vespidae: Vespinae). It has been hypothesized that it is a hunger signal, but there is little empirical evidence to support this claim. An alternative hypothesis is that GD recruits workers to forage for food. Here, we report the results of a test between the hunger-signal and food-recruitment hypotheses in the German yellowjacket wasp, Vespula germanica. We show that the rate of performance of GD decreased when colonies were deprived of food and increased when supplemental food was provided. Playback of GD caused increased rates of (1) movement in the nest, (2) trophallaxis, and (3) worker departures from the nest. Together, these results support the conclusion that GD is not a hunger signal as previously asserted but instead is a nest-based food-recruitment signal, the first to be reported for a social wasp.     

Highly modular pattern in ant-plant interactions involving specialized and non-specialized myrmecophytes

Because Tachia guianensis (Gentianaceae) is a “non-specialized myrmecophyte” associated with 37 ant species, we aimed to determine if its presence alters the ant guild associated with sympatric “specialized myrmecophytes” (i.e., plants sheltering a few ant species in hollow structures). The study was conducted in a hilly zone of a neotropical rainforest where two specialized myrmecophytes grow at the bottom of the slopes, another at mid-slope, and a fourth on the hilltops. Tachia guianensis, which occurred everywhere, had its own guild of associated ant species. A network analysis showed that its connections with the four other myrmecophytes were rare and weak, the whole resulting in a highly modular pattern of interactions with one module (i.e., subnetwork) per myrmecophyte. Three ant species parasitized three out of the four specialized myrmecophytes (low nestedness noted), but were not or barely associated with T. guianensis that therefore did not influence the parasitism of specialized myrmecophytes.     

Ecosystem-based adaptation to climate change: defining hotspot municipalities for policy design and implementation in Brazil

We developed an indicator that defines priority municipalities in order to facilitate the deployment of preventive policies and strategies for ecosystem-based adaptation to climate change (EbA) in Brazilian municipalities. Based on the premises that poor people are the population most vulnerable to climate change and that conservation and sustainable use of biodiversity and ecosystems are adaptive to climate change, our indicator uses three parameters: (1) poverty, (2) proportion of natural-vegetation cover, and (3) exposure to climate change. Thus, we searched for Brazilian municipalities that simultaneously belonged to the quartile of municipalities with the highest percentage of poverty, the quartile with the highest percentage of natural-vegetation cover, and the quartile with the highest exposure indices in two global climate models (Eta-HadGEM, Eta-Miroc). We found 398 (7.1%) EbA hotspots among 5565 Brazilian municipalities, which comprise 36% of the total area of native remnants in the country and are home to 22% of the poor people in Brazil. In their majority, these municipalities cover significant portions of the Amazon, Cerrado, Caatinga, and Atlantic forest, and indeed, these regions are recognised as some of the most vulnerable to climate change in the world. Considering the relevance of these biomes for the global water and nutrient cycle (Amazon), global food security (Cerrado), vulnerability to desertification (Caatinga), and biodiversity (all) we discuss the adaptive strategies in place, the need to bring them to scale, and existing policy gaps. Finally, in an effort to guide international and national investment and policies, we discuss how the approach described here can be applied to societies inhabiting tropical forests, savannas, and semiarid zones in other parts of the world. In particular, we propose that the indicator developed here is a simple and fast way to achieve early detection of priority municipalities for deployment of EbA action and policies, particularly in tropical developing countries.     

Biological oxidation of arsenite: batch reactor experiments in presence of kutnahorite and chabazite

Arsenic represents a threat to all living organisms due to its toxicity which depends on its speciation. This element is carcinogenic, teratogenic and is certainly one of the most important contaminants affecting millions of people around the world. Abiotic and biotic processes control its speciation and distribution in the environment. We have previously shown that a new bacterial strain named ULPAs1 performed oxidation of As(III) (1.33 mM) to As(V) in batch cultures. In order to develop new methods to remove arsenic from contaminated effluents or waste, by bacterial oxidation of As(III) to As(V) followed by its sorption, the conservation of oxidative properties of ULPAs1 was investigated when cultivated in batch reactors in the presence of two solid phases, chabazite and kutnahorite, already used as microorganisms immobilizing materials in biological remediation processes. In parallel, the retention efficiency of these solid phases toward arsenic ions and particularly arsenate was studied. Pure quartz sand was used as a reference material. Kutnahorite efficiently sorbed As(V), chabazite alone performed As(III) oxidation and pure quartz sand did not sorb arsenic at all. The arsenite oxidative properties of ULPAs1 were conserved when cultivated in the presence of quartz or chabazite.     

Chemical defense of the ladybird beetle Epilachna paenulata

Summary. The defensive chemistry of the ladybird beetle Epilachna paenulata (Coleoptera: Coccinellidae) was characterized as a mixture of piperidine, homotropane and pyrrolidine alkaloids. Whole body extracts of adult beetles contain four major alkaloids: 1-(6-Methyl-2,3,4,5-tetrahydro-pyridin-2-yl)-propan-2-one; 1-(6-methyl-2-piperidyl)-propan-2-one; 9-aza-1-methyl-bicyclo[3.3.1]nonan-3-one and 1- (2′′- hydroxyethyl)-2-(12′-aminotridecyl)-pyrrolidine. Comparative studies of the defensive chemistry of eggs, larvae, pupae and adults showed both qualitative and quantitative differences in alkaloid composition among the four life stages, and also within adult age. Laboratory predation bioassays with wolf spiders showed that the adults are better protected than the larvae and pupae. Field tests showed the adult alkaloid extract to be deterrent to ants.     

Elemental composition of otolith growth marks in three geographically separated populations of European hake (Merluccius merluccius)

The composition of the opaque and translucent bands in the otoliths of European hake (Merluccius merluccius) from three different populations (Celtic Sea, Galicia shelf and Cretan Sea) was analysed with wavelength dispersive spectrometry (WDS) and differences in Ca, Sr and Na were compared. The translucent bands (annual marks and checks altogether) were significantly richer in Sr and Ca and significantly poorer in Na than opaque bands. Results support the idea of a more compact arrangement of crystals in translucent bands compared to opaque. Analyses did not help to discriminate between putative annual marks and checks. Clear differences in the range of Sr/Ca variation across the otolith as well as in the composition of the otolith core were observed among the three populations. As a result it was possible to discriminate the natal origin of each fish using the composition of the otolith core in Ca, Sr and Na. Nevertheless, the overall pattern across the otolith was similar among the three populations suggesting the existence of ontogenetic trends. Variation of Na/Ca ratios was largely uninformative. Based on these results, a conceptual model for hake is proposed which integrates the different sources of otolith Sr/Ca variation: ambient Sr/Ca, endogenous cues (ontogeny) and exogenous cues (environment).     

Juvenile growth of the polychaete Nereis virens feeding on a range of marine vascular and macroalgal plant sources

A laboratory experiment was conducted to examine variation of juvenile growth (% d^-1) of the polychaete Nereis virens (Sars) in relation to tidal flat plant species as food sources. We used vegetable materials (algae and vascular plants) which are carried along by tidal currents and are found abundantly at the upper tidal level. Juveniles (2-yr-old) markedly increased in wet weight with the algae Laminaria longicruris (weight-specific growth rate : 1.7% d^-1) and Enteromorpha intestinalis (: 1.6% d^-1) as food sources. A higher value of assimilation efficiency was observed for algal species (L. longicruris 55.1±7.9%; E. intestinalis 54.8±0.5%; Fucus vesiculosus 40.6%) than for marine vascular plants (Spartina alterniflora 26.8±10.9%; Zostera marina 1.4%). The digestion of marine vascular species lasts longer (19 to 38 h) than that of algal species. All these characteristics (growth, assimilation efficiency and duration of the digestive process) seem to correlate positively with lignin and cellulose concentrations in the plant structure.