SHORT COMMUNICATION Should the use of inhibition of cholinesterases as a specific biomarker for organophosphate and carbamate pesticides be questioned

Recently there has been evidence that contaminants other than organophosphate and carbamate pesticides may inhibit the activity of the enzyme acetylcholinesterase (AChE) both under in vitro and in vivo conditions. In this study we investigated the in vitro effect of three detergents \[dodecyl benzyl sulphonate (DBS), sodium dodecyl sulphate (SDS) and a mixture commonly used as domestic detergent (X)] and three metals \[molybdenum, barium and chromium (VI)] on AChE activity of Mytilus galloprovincialis haemolymph. All the detergents tested significantly inhibited the activity of the enzyme. The lowest observed effect concentrations were equal to 12 5 for DBS and 50 mg l-1 for SDS and X. Among the metals, molybdenum and barium had no effect on AChE activity, whereas chromium (VI) significantly depressed the activity of the enzyme at concentrations equal to or higher than 25 mg l-1. These results suggest that the use of AChE as a specific biomarker for organophosphate and carbamate pesticides should be questioned and that the use of this enzyme as a biomarker could be extended.     

Evolution of Dendrocolaptes platyrostris (Aves: Furnariidae) between the South American open vegetation corridor and the Atlantic forest

The open vegetation corridor of South America is a region dominated by savanna biomes. It contains forests (i.e. riverine forests) that may act as corridors for rainforest specialists between the open vegetation corridor and its neighbouring biomes (i.e. the Amazonian and Atlantic forests). A prediction for this scenario is that populations of rainforest specialists in the open vegetation corridor and in the forested biomes show no significant genetic divergence. We addressed this hypothesis by studying plumage and genetic variation of the Planalto woodcreeper Dendrocolaptes platyrostris Spix (1824) (Aves: Furnariidae), a forest specialist that occurs in both open habitat and in the Atlantic forest. The study questions were: (1) is there any evidence of genetic continuity between populations of the open habitat and the Atlantic forest and (2) is plumage variation congruent with patterns of neutral genetic structure or with ecological factors related to habitat type? We used cytochrome b and mitochondrial DNA control region sequences to show that D. platyrostris is monophyletic and presents substantial intraspecific differentiation. We found two areas of plumage stability: one associated with Cerrado and the other associated with southern Atlantic Forest. Multiple Mantel tests showed that most of the plumage variation followed the transition of habitats but not phylogeographical gaps, suggesting that selection may be related to the evolution of the plumage of the species. The results were not compatible with the idea that forest specialists in the open vegetation corridor and in the Atlantic forest are linked at the population level because birds from each region were not part of the same genetic unit. Divergence in the presence of gene flow across the ecotone between both regions might explain our results. Also, our findings indicate that the southern Atlantic forest may have been significantly affected by Pleistocene climatic alteration, although such events did not cause local extinction of most taxa, as occurred in other regions of the globe where forests were significantly affected by global glaciations. Finally, our results neither support plumage stability areas, nor subspecies as full species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103 , 801–820.     

Phylogenetic and phenotypic originality and abundance in a cerrado plant community

The originality of a species is how much that species contributes to the rarity of traits in a community. Here we tested the relation between abundance and both phylogenetic and phenotypic originality. We measured nine traits associated with defence against herbivory, as well as phylogenetic information and abundance for woody plant species in a woodland cerrado in southeastern Brazil. About 90% of the species accounted for about 50% of the phylogenetic and phenotypic originality: most woody species had low originality. Abundance was related to tougher leaves, lower specific leaf area and lower originality based on nutritional quality. Our results suggest that herbivory may reduce the abundance of species with low resistance to herbivory and with different nutritional quality. Nevertheless, abundance was not related to either phylogenetic or phenotypic originality, so extinction of rare species may not endanger overall community function as long as more abundant species are retained. We argue that this is a consequence of the low complementarity of a large number of woody species.     

Floral biology of Eriope blanchetii (Lamiaceae) in coastal sand dunes of NE Brazil

Abstract The floral biology of the sand dune shrub Eriope blanchetii (Benth) Harley was investigated in a wild population located within an environment protection area near Salvador, NE Brazil. Inflorescence and flower development were monitored, and the reproductive biology was assessed. Inflorescences are terminal panicles, each bearing from one to 38 small, zygomorphic flowers. The duration of an inflorescence is about 2 months, with few new flowers each day. The rewards to visitors are pollen and nectar, the latter being produced in small quantities at the corolla base, near the stylopodium. Three sequential phases of flower development were identified, based on colour changes, pollen and nectar availability, and stigmatic receptivity. Anthesis takes place throughout the day within each plant, and flowers are strongly protandrous. Flowers are short‐lived, with individual variations of 7–30 h until corolla abscission. This variation is probably associated to a post‐pollinating response, which reduces the length of the female phase and could be advantageous for the economy of nectar production and for increased efficient pollination of the remaining flowers on a plant. The results of the pollination tests (apomixis, spontaneous and manual autogamy, manual cross‐pollination, and control) reinforced the role of pollinators for the reproductive success of E. blanchetii, given that the production of fruits from spontaneous pollination is unlikely to be resulting from protandry and given the morphological floral features. Taken together, the morphological and physiological aspects of E. blanchetii floral biology favour cross‐pollination, and it is likely that most of the fruits in nature are produced by outcrossing.     

Patterns and rates of nucleotide substitution,insertion and deletion in the endosymbiont of ants Blochmannia floridanus

Genome reduction is a general process that has been studied in numerous symbiotic bacteria associated with insects. We investigated the last stages of genome degradation in Blochmannia floridanus, a mutualistic bacterial endosymbiont of the ant Camponotus floridanus. We determined the tempo (rates of insertion and deletion) and mode (size and number of insertion–deletion events) of the process in the last 200 000 years by analysing a total of 16 intergenic regions in several strains of this endosymbiont from different ant populations. We provide the first calculation of the reduction rate for noncoding DNA in this endosymbiont (2.2 × 10^?8 lost nucleotides/site/year) and compare it with the rate of loss in other species. Our results confirm, as it has been observed in other organisms like Buchnera aphidicola or Rickettsia spp., that deletions larger than one nucleotide can still appear in advanced stages of genome reduction and that a substitutional deletion bias exists. However, this bias is not due to a higher proportion of deletion over insertion events but to a few deletion events being larger than the rest. Moreover, we detected a substitutional AT bias that is probably responsible for the increase in the number of the small and moderate indel events in the last stages of genome reduction. Accordingly, we found intrapopulational polymorphisms for the detected microsatellites in contrast to the stability associated with these in free‐living bacteria such as Escherichia coli.     

Distribution of Epitopes of Trypanosoma cruzi Amastigotes During the Intracellular Life Cycle within Mammalian Cells

ABSTRACT. In this study we have examined the distribution of epitopes defined by monoclonal antibodies raised against Trypanosoma cruzi amastigotes during the intraceullar life cycle of the parasite. We have raised monoclonal antibodies towards amastigote forms and performed preliminary immunochemical characterization of their reactivities. MAB 1D9, 3G8, 2B7, 3B9, and 4B9, and 4B9 react with carbohydrate epitopes of the parasite major surface glycoprotein—Ssp-4 defined by MAB 2C2 [5]: MAB 4B5 reacts with a noncarbohydrate epitope in all developmental stages of the parasite, and MAB 3B2 also detects a noncarbohydrate epitope preferentially in T. cruzi flagellared forms. Vero cells infected with tissue culture-derived trypomastigotes of clone D11 (G strain) were fixed at different times during the intraceullular proliferation of parasites, and processed for immjno-electron microscopy and confocal immunoflurescence with the different monoclonal antibodies. We observed that while the surface distribution of MAB 2C2 and 4B9 epitopes was uniform throughout the cycle, MAB 1D9, 3G8, and 2B7 reacted with cytoplasmic membrance-bound compartments of the amastigotes. MAB 3B9 displayed a unique surface dentate pattern in some amastigotes. MAB 4B5 recognized a curved-shaped structure at the flagellar pocket region in some intracellular amastigotes and localized to the membrane in dividing forms. In intracellular trypomastigotes, MAB 4B5 also displayed a punctate pattern near the flagellar pocket.     

Implications of the mastoid anatomy of larger extant felids for the evolution and predatory behaviour of sabretoothed cats (Mammalia, Carnivora, Felidae)

Muscle attachments in the mastoid region of the skull of extant felids are studied through dissection of two adult tigers Panthera tigris (Linnaeus, 1758) Pocock, 1930, a lion Panthera leo (Linnaeus, 1758) Pocock, 1930 and a puma Puma concolor (Linnaeus, 1771) Jardine, 1834, providing for the first time an adequate reference for the study of the evolution of that region in sabretoothed felids. Our study supports the inference by W. Akersten that the main muscles inserting in the mastoid process in sabretooths were those originating in the atlas, rather than those from the posterior neck, sternum and forelimb. Those inferences were based on the anatomy of the giant panda, Ailuropoda melanoleuca (David, 1869) Milne-Edwards, 1870, raising uncertainties about homology, which were founded, as revealed by our results. The mastoid muscle insertions in extant felids differ in important details from those described for Ailuropoda , but agree with those described for domestic cats, hyenas and dogs. The large, antero-ventrally projected mastoid process of pantherines allows a moderate implication of the m. obliquus capitis anterior in head-flexion. This contradicts the widespread notion that the function of this muscle in carnivores is to extend the atlanto-cranial joint and to flex it laterally, but supports previous inferences about the head-flexing function of atlanto-mastoid muscles in machairodontines. Sabretooth mastoid morphology implies larger and longer-fibred atlanto-mastoid muscles than in pantherines, and that most of their fibres ran inferior to the axis of rotation of the atlanto-occipital joint, emphasizing head-flexing action.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 207–221.