Phycobiliproteins extract from Spirulina protects against single-dose cadmium-induced reproductive toxicity in male mice

Environmental Science and Pollution Research - Cadmium (Cd) is known for its many toxic effects on male population such as hypogonadism and fertility difficulties, which are oftenly associated with...     

Tree recruitment in an empty forest

To assess how the decimation of large vertebrates by hunting alters recruitment processes in a tropical forest, we compared the sapling cohorts of two structurally and compositionally similar forests in the Rio Manu floodplain in southeastern Peru. Large vertebrates were severely depleted at one site, Boca Manu (BM), whereas the other, Cocha Cashu Biological Station (CC), supported an intact fauna. At both sites we sampled small (> or =1 m tall, <1 cm dbh) and large (> or =1 cm and <10 cm dbh) saplings in the central portion of 4-ha plots within which all trees > or =10 cm dbh were mapped and identified. This design ensured that all conspecific adults within at least 50 m (BM) or 55 m (CC) of any sapling would have known locations. We used the Janzen-Connell model to make five predictions about the sapling cohorts at BM with respect to CC: (1) reduced overall sapling recruitment, (2) increased recruitment of species dispersed by abiotic means, (3) altered relative abundances of species, (4) prominence of large-seeded species among those showing depressed recruitment, and (5) little or no tendency for saplings to cluster closer to adults at BM. Our results affirmed each of these predictions. Interpreted at face value, the evidence suggests that few species are demographically stable at BM and that up to 28% are increasing and 72% decreasing. Loss of dispersal function allows species dispersed abiotically and by small birds and mammals to substitute for those dispersed by large birds and mammals. Although we regard these conclusions as preliminary, over the long run, the observed type of directional change in tree composition is likely to result in biodiversity loss and negative feedbacks on both the animal and plant communities. Our results suggest that the best, and perhaps only, way to prevent compositional change and probable loss of diversity in tropical tree communities is to prohibit hunting.     

Characterization of acute toxicity,genotoxicity, and oxidative stress of dimethoate in Rhinella arenarum larvae

Environmental Science and Pollution Research - There is a great concern worldwide about the global decline of amphibians, particularly by agrochemical pollution. The aim of this study was to assess...     

Isolation and identification of intermediates from biodegradation of low chlorinated biphenyls (Delor-103)

Microorganism Pseudomonas species P2 metabolizes polychlorinated biphenyls (PCBs) and biphenyl, producing the whole spectrum of intermediates, among them coloured intermediates, which are suitable for the monitoring of PCBs degradation by optical sensors. Knowledge of chemical structures and conditions of development of colour metabolites is necessary for application of optical analytical methods. The main goal of this work was the isolation and identification of intermediates from the biodegradation of the mixture of low chlorinated biphenyls (Delor-103), which is based on the solid phase extraction (SPE) of the whole mixture using LiChrolut EN cartridges, then silylation of the extract as one way to the identification of one part of intermediates by GC-MS, and acetylation of the extract as a way for the further concentration and analysis of more polar chlorobiphenylols and chlorobiphenyldiols. The combination of SPE and following acetylation allows to obtain chlorobiphenylols and chlorobiphenyldiols as an almost pure fraction. The acetylation method could be also used instead SPE procedure with the same final concentration effect. Using the simulation mass spectrometry program, two new compounds, dihydrodihydroxytrichloro- and tetrahydrodihydroxytrichlorobiphenyl, as silylderivatives, were identified.     

Desperado siblings: uncontrollably aggressive junior chicks

According to the desperado sibling hypothesis, chicks of obligately siblicidal species kill their junior broodmates as early as possible because junior broodmates face dire ecological prospects and are consequently predisposed to aggressively overthrow elder broodmates by all-out aggression. The agonistic behavior of junior chicks is virtually unknown because they die so young. We investigated the agonistic behavior of hypothetical desperados by fostering junior brown boobies (Sula leucogaster, an obligately siblicidal species) into nests of the blue-footed booby (S. nebouxii, a facultatively siblicidal species) containing an older singleton blue-foot chick. Controls were junior blue-footed boobies fostered into the same situation. Junior brown boobies were 7 times more aggressive than controls and most of them dominated their elder and larger nestmates. Four of nine brown booby juniors showed relentless aggression, delivering up to 711 pecks, bites and pushes (including "expulsion pushes") per hour, thereby overwhelming nestmates 90% heavier and permanently expelling one of them from the nest. Similarly, in natural broods of two surviving brown booby chicks, the losing chick was 13 times as aggressive as blue-foot subordinates, up to at least age 7 weeks. Contrast of the two species of booby suggests the evolution of agonistic roles within broods may be partly driven by selection on potential victims to express a level and type of aggressiveness appropriate to their status-related ecological prospects.     

Negative interactions between two SW Atlantic intertidal crabs in soft-bottom habitats

The intertidal crabs Chasmagnathus granulatus and Cyrtograpsus angulatus coexist across the SW Atlantic intertidal. Previous studies in this region suggest that C. granulatus displace C. angulatus in soft sediment, where C. granulatus build burrows (“burrowing beds”). We examined variation in abundance, size-frequency distribution, sex ratio, incidence of autotomies, and diet of both species in C. granulatus crab beds and adjacent areas without burrows. We also experimentally tested the hypothesis that in the absence of C. granulatus, C. angulatus will build burrows. Only large sized individuals of C. angulatus venture into C. granulatus crab beds. The sex ratio of C. angulatus was always biased towards females, with higher bias outside crab beds (1:8 outside, 1:2 inside). Although the items consumed in the crab beds did not differ from those consumed outside, the males of C. angulatus had a higher frequency of empty stomachs in crab beds. The incidence of limb autotomies of C. angulatus was higher outside C. granulatus crab bed areas. After a long rainy period in which C. granulatus was absent from these areas, the pattern of habitat use of C. angulatus changed. During this period C. angulatus showed higher abundance in the areas, where C. granulatus previously constructed burrows, and there were no differences between areas in any of the measured parameters. In the absence of C. granulatus, C. angulatus built their own burrows and never used C. granulatus burrows. The interaction between C. granulatus and C. angulatus may be a good example of competitive exclusion, when the shared resource is the access to surface soft-sediment.     

Biotoxizitätstests mit PAK

There is great need for toxicity tests with higher plants for the investigation and monitoring of chemicals in the environment — especially for tests which are quick, easy, and inexpensive. Such tests should add to and improve current guidelines, e.g., OECD- and BBA-Guidelines. This article describes the nodulation of leguminous plants withRhizobium bacteria used in a bioassay with polycyclic aromatic hydrocarbons (PAH). Plants growing on a solid medium were exposed simultaneously to bacteria and PAH. This axenic culture system allows to observe the impact of PAH on plant growth and the interaction between plant and bacteria (nodulation). Dose-response-experiments indicated that nodulation measured as number of nodules per plant, was more sensitive to the inhibition by PAH than other plant growth parameters.     

The appreciation of mineral element accumulation level in some herbaceous plants species by ICP–AES method

Introduction  

From the metallurgic industry zone of Dambovita County, we harvested and analyzed seven herbaceous plants species (Lolium perenne, Festuca pratensis, Stipa capillata, Agrostis alba, Cynodon dactylon, Luzula campestris, and Agrostis tenuis) to establish the heavy metal accumulation levels in these species.     

Use of sequential extraction to assess the influence of sewage sludge amendment on metal mobility in Chilean soils

In Chile, the increasing number of plants for the treatment of wastewater has brought about an increase in the generation of sludge. One way of sludge disposal is its application on land; this, however involves some problems, some of them being heavy metal accumulation and the increase in organic matter and other components from sewage sludge which may change the distribution and mobility of heavy metals. The purpose of the present study was to determine the effect of sewage sludge application on the distribution of Cr, Ni, Cu, Zn and Pb in agricultural soils in Chile. Three different soils, two Mollisols and one Alfisol, were sampled from an agricultural area in Central Chile. The soils were treated with sewage sludge at the rates of 0 and 30 ton ha(-1), and were incubated at 25 degrees C for 45 days. Before and after incubation, the soils were sequentially extracted to obtain labile (exchangeable and sodium acetate-soluble), potentially labile (soluble in moderately reducing conditions, K4P2O7-soluble and soluble in reducing conditions) and inert (soluble in strong acid oxidizing conditions) fractions. A two-level factored design was used to assess the effect of sludge application rate, incubation time and their interaction on the mobility of the elements under study. Among the metals determined in the sludge, zinc has the highest concentration. However, with the exception of Ni, the total content of metals was lower than the recommended limit values in sewage sludge as stated by Chilean regulations. Although 23% of zinc in sludge was in more mobile forms, the residual fraction of all metals was the predominant form in soils and sludge. The content of zinc only was significantly increased in two of the soils by sewage sludge application. On the other hand, with the exception of copper, the metals were redistributed in the first four fractions of amended soils. The effect of sludge application rate, incubation time and their interaction depended on the metal or soil type. In most cases an increase in more mobile forms of metals in soils was observed as the final effect.     

Determination of pesticides of different chemical classes in drinking water of the state of Santa Catarina (Brazil) using solid-phase microextraction coupled to chromatographic determinations

The evaluation of the concentration of pesticides in drinking water presents a real concern. In this study, a simple and rapid method based on solid-phase microextraction (SPME) followed by gas chromatography–mass spectrometry and electron capture detectors was developed aiming at multiclass determination of 23 pesticides regulated by the Brazilian legislation. The extraction was carried out by direct immersion mode (DI-SPME) using DVB/Car/PDMS fiber coating. In order to improve the extraction efficiency, parameters such as temperature, salting-out effect, and extraction time were optimized. The method was evaluated using drinking water samples spiked with the analytes at different concentrations, and it showed good linearity in the range studied. The values obtained for limits of quantification (LOQ) were below the limits established by Brazilian regulations. Accuracy and precision of the method exhibited satisfactory results, providing relative recoveries from 70 to 123.34% at three spiked levels, and the relative standard deviations ranged from 0.53 to 24.8%. The method was applied in 20 drinking water samples from 13 cities in the State of Santa Catarina, Brazil.