Deforestation and sewage effects on aquatic macroinvertebrates in urban streams in Manaus,Amazonas, Brazil

In the last few years, awareness in developed countries has increased regarding the importance of urban watercourses as essential natural resources for human well being. Macroinvertebrates have been used as bioindicators to complement physico-chemical evaluation of water quality after environmental perturbations. The city of Manaus is closely associated with the Amazonian rain forest and with its dense hydrographic network. Any perturbation, such as deforestation and/or water pollution in the city’s streams, therefore causes changes in the local ecosystem as the population increases. In this study, 65 streams were sampled in October and November 2003. Samples were taken from stream-bed sediment in the center of the channel and litter/sediment at the edge of the stream. Deforestation, total Nitrogen (TN), total Phosphorus (TP), depth, width, electrical conductivity, temperature and dissolved Oxygen (DO) were measured. A total of 115,549 specimens were collected, distributed among 152 taxa. Oligochaeta, Chironomus, Psychodidae and Ceratopogonidae were the taxa with the greatest frequencies of occurrence and the highest total abundances. Higher deforestation, TN and TP were correlated with lower DO and greater electrical conductivity, pH and water temperature. Deforestation, TN and TP were not associated with water velocity and stream width. Depth was the only variable correlated (negatively) with deforestation and not correlated with TN and TP. Greater deforestation, TN and TP were correlated with lower richness of taxa; but these variables did not affect abundance. Canonical Correspondence Analysis ordenated the streams into two groups; the majority of the streams were in the group with high levels of deforestation and with high values of TP, TN, pH, electrical conductivity and temperature, where the macroinvertebrates were reduced to a few taxa. The other group was composed of streams that were well oxygenated and deep, where richness of taxa was higher. These results indicate changes in community composition in response to changes in environmental conditions. The highest taxa correlation was with streams that were well oxygenated and had the greatest depth and water velocity. Species Indicator Analysis identified 29 taxa as indicators of nonimpacted streams, 16 as indicators of deforested streams and three as indicators of streams impacted by deforestation and domestic sewage. Of the total sampled streams, 80% were impacted by deforestation and water pollution and had fauna tolerant of these perturbations. Water pollution, represented by TN and TP, affected the macroinvertebrate fauna in a way similar to deforestation, i.e., causing reduction in taxa richness, simplifying the insect community composition without changing abundance. Use of the taxa suggested in this study as environmental indicators could improve the evaluation of water quality in the streams in Central Amazonia. Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users. Handling editor: D. Dudgeon     

Spatial-temporal distribution of preimaginal blackflies in Neotropical streams

The current study investigates the spatial-temporal distribution of preimaginal blackflies in three a priori established, adjacent areas of Brazil and Venezuela. First we tested the hypothesis that the distribution of individual simuliid species, over two geographic scales, were predictable on the basis of several habitat parameters. Secondly, we determined if local species assemblages remain constant over two spatial axes, i.e., were species assemblages predictable within and between defined regions. Finally we compared the species assemblage between Venezuelan streams sampled in both the wet (October) and dry (February) seasons. As stream conditions changed across a north–south gradient, so did the occurrence of the most common species. This change in species composition from upland to lowland areas is consistent with the patterns of faunal change seen in North American simuliid assemblages. Discriminant Function Analysis showed a strong association between regional demarcations and stream site conditions. These results were paralleled by the strong correspondence between species assemblages and these regions. Thus each region presented both distinct stream environments and species assemblages. Monte Carlo analysis suggests that some if not all species are not only present in both the wet and dry season but that they are continuing to use the same stream sites. Three broad contingent rules for blackfly species assemblages in new world streams are put forward; (i) the ubiquitous nature of simuliids; (ii) species often distribute themselves along an axis of stream size and; (iii) there is a strong and consistent correspondence between regional characteristics of streams and the species assemblage.     

What affects the desiccation tolerance threshold of Brazilian Eugenia (Myrtaceae) seeds?

Desiccation sensitive (DS) seeds are shed at high water contents (WC) and metabolically active, but WC thresholds vary broadly among species even in the same genus. Eugenia is an important ecological genus that has high occurrence in several Brazilian morphoclimatic domains. In this study, we assessed seed desiccation tolerance of five Eugenia species collected in specific meteorological conditions. We reported the species geographical ranges and verified the rainfall and temperature of species sites in the year prior to seed collection. We also assessed initial WC, seed germination and vigor and seedling growth upon desiccation. Eugenia uniflora was the widest spread among the five species, while E. astringens was the most restricted. In this specific study, widespread species showed a higher WC threshold than restricted species. In the same way, the WC of fresh seeds was not correlated to the desiccation tolerance threshold. Seed desiccation tolerance was species dependent and correlated with the environmental status of seed collection sites. Wetter and warmer conditions were correlated to the E. uniflora higher DS threshold. Low rainfall and temperature corresponded to a lower desiccation sensitivity of E. astringens seeds. Seeds of the five species lost half viability between 0.44 and 0.25 g H₂O g DW^??1 and after 65–270 h of desiccation. Our results indicate that abiotic factors impact plant populations during the seed production season and can drive seed desiccation tolerance threshold and physiological behavior. These results should be taken into account in ex-situ plant conservation programs and tropical species management.

     

Leaf litter quality drives the feeding by invertebrate shredders in tropical streams

Amazon and Cerrado‐forested streams show natural fluctuations in leaf litter quantity along the time and space, suggesting a change on litter quality input. These natural fluctuations of leaf litter have repercussion on the organic matter cycling and consequently effects on leaf decomposition in forested streams. The effects of the quantity of leaf litter with contrasting traits on consumption by larvae of shredder insects from biomes with different organic matter dynamics have still been an understudied question. The Trichoptera Phylloicus spp. is a typical shredder in tropical headwater streams and keep an important role in leaf litter decomposition. Here, we assessed the consumption by shredder Phylloicus spp., from Amazonia and Cerrado biomes, on higher (Maprounea guianensis) and lower quality leaves (Inga laurina) in different proportions and quantities. Experiments were performed concomitantly in microcosms approaches, simulating Cerrado and Amazonian streams. Higher leaf consumption occurred in Cerrado microcosms. Litter quantity influenced negatively leaf consumption by shredders in Cerrado, in opposition to Amazonia, where consumption was not affected by leaf quantity. In both sites, we observed higher consumption by shredders in treatment with only M. guianensis and no difference between other treatments with mixture of leaves. In treatment with litter of I. laurina, we noted the use of substrate for case building (due to the higher leaf toughness), affecting the fragmentation process. Therefore, our results indicate that leaf litter quality drives the preference of consumption by Phylloicus larvae in Cerrado and Amazonia streams.     

Application of real-time PCR stool assay for Helicobacter pylori detection and clarithromycin susceptibility testing in Brazilian children

Background: Helicobacter pylori ClariRes assay is a novel commercially available real‐time PCR assay allowing H. pylori detection and clarithromycin susceptibility testing in either gastric biopsy or stool specimens. Objective: The aim of this study was to validate the novel biprobe real‐time assay in stool specimens from 217 dyspeptic children. Methods: DNA from gastric biopsies and stool specimens were obtained and submitted to the biprobe real time assay for H. pylori detection and clarithromycin susceptibility testing. Results: The sensitivity, specificity, and test accuracy were 69, 100 and 93.9% for the detection of H. pylori infection and 83.3, 100 and 95.6%, for detection of clarithromycin resistance. Conclusion: This assay proved to be appropriate for H. pylori clarithromycin susceptibility testing, particularly in children populations where a high prevalence of clarithromycin‐resistant strains is suspected.     

Integrating approaches towards the conservation of forest genetic resources: a case study of Araucaria angustifolia

In the past years the conservation of forest genetic resources has been widely recognized because of the risk of adverse effects associated with global changes in the environment. Since little effort has been made towards conservation of these resources, the assessment and the integration of information and knowledge so far generated are valuable tools in order to promote their conservation. In the present work the Brazilian conifer Araucaria angustifolia was used as a case study, integrating information, published between 1980 and 2007, about genetics, biotechnology, palaeobotany, and archeology. These studies were interpreted towards the conservation needs and strategies of the species germplasm. The main conclusions for the conservation of A. angustifolia genetic resources are: (1) despite the reduction of genetic diversity by unsustainable forest exploitation, the genetic system of A. angustifolia seems to be efficient to protect this species against rapid losses of its genetic diversity; (2) conservation measures starting now may be efficient, since the genetic structures of existing populations is more largely influenced by the past evolutionary process than by human disturbance occurred in the last century; (3) there are opportunities to save the genetic resources of the species, if simple measures are taken to safeguard the continued existence of the few remaining araucaria forests. Emerged as a general conclusion that the use of sound scientific arguments supported by different areas of the science could be a very powerful instrument in persuading decision-makers, also by governments, taking into account forest genetic resources as a primary issue for the future.     

Synergistic Effect Between Ouabain and Glucocorticoids for the Induction of Thymic Atrophy

The present report shows that thymocyte death, induced by glucocorticoids, may be modulated in vivo by ouabain. Young, ten days old, mice injected with 140 mg/kg sodium succcinate of hydrocortisone (HC) intraperitonially (i.p.) displayed, 24 h after the injection, a decrease in thymus size and cellular content, an effect that was magnified when ouabain (OUA) 0.56 mg/kg, i.p. was given 1 h prior to the HC injection. Ouabain per se was not capable of producing these changes. Both HC and the combination OUA plus HC induced the death of immature double positive lymphocytes (CD4⁺CD8⁺) whereas CD69⁺ cells survived both treatments. An increase in annexin positive cells and a decrease in mitochondrial membrane potential, assessed by cytofluorimetry, using the fluorescent dye DiOC₆, was observed in thymocytes from HC treated animals indicating apoptosis of these cells. Furthermore, a synergistic effect between OUA and HC was also observed using this parameter. The synergy observed in the thymus of animals treated with glucocorticoids and OUA might occur under stress, when both hormones are released, or in situations when ouabain is administered exogenously in a moment of the circadian cycle when glucocorticoid levels are elevated. However the impact of this effect on the immune response is still unknown.     

Invasion of HeLa cells byEdwardsiella tarda

TwelveEdwardsiella tarda strains investigated proved to be strongly invasive for HeLa cells. All strains were negative in the Serény test and did not produce either enterotoxins LT and ST or cytotoxin detectable by the Y1, the infant mouse, and the Vero tests respectively. All strains were hemolytic on blood agar plates.     

The behavior of the coiled body in cells infected with adenovirus in vitro

The coiled body is a phylogenetically conserved nuclear organelle whose function is not known. Probes for detection of p80-coilin, an 80 kDa protein enriched in the coiled body, have made possible studies determining the behavior of the coiled body during the cell cycle, in proliferating cells, as well as reports suggesting some relationship of the coiled body to mRNA splicing and to the nucleolus. The objective of this study is to examine the distribution of p80-coilin and nucleolar proteins in cells infected with adenovirus in vitro. HeLa cells grown as monolayers were infected with successive dilutions of type 5 human adenovirus culture and fixed in methanol/acetone at different time points. Single and double indirect immunofluorescence was performed with human autoantibodies to p80-coilin, fibrillarin, NOR-90/hUBF, RNA polymerase I, PM-Scl, and To, as well as rabbit polyclonal serum to p80-coilin (R288) and mouse monoclonal antibody to adenovirus 72-kDa DNA-binding protein. Indirect immunofluorescence (IIF) with anti- p80-coilin antibodies showed that the usual bright dot-like coiled body staining pattern was replaced in infected cells by 1–5 clusters of tiny dots at the periphery of the nucleus. This phenomenon was first detected within 12 h of infection and affected more severely cells with increased length and load of infection. Cells subjected to heat shock presented no such alteration. Double IIF showed that cells with abnormal coiled body appearance expressed the viral 72-kDa DNA-binding protein. Nucleolar proteins RNA polymerase I and NOR-90/hUBF became associated with the p80-coilin-enriched clusters and were no longer detected in the nucleolus. Other nucleolar proteins, like PM-Scl and To, remained associated to the nucleolus and were not detected in the newly formed clusters. Fibrillarin had a heterogeneous behavior, being restricted to the nucleolus in some infected cells while in some others it was associated with the p80-coilin-enriched clusters. Thus our results showed that in vitro adenovirus infection induced radical redistribution of nucleolar and coiled body constituents into newly formed structures characterized by clusters of tiny dots in the periphery of the nucleus. The fact that three major proteins involved in rRNA synthesis and processing colocalized with p80-coilin in these clusters may bring additional support to the idea that the coiled body and p80-coilin may be implicated in functions related to the nucleolus.     

Cytotaxonomy of Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz (Diptera: Simuliidae) in Brazilian Amazonia

Simulium cauchense Floch & Abonnenc and Simulium quadrifidum Lutz are widely distributed in the Amazon region and are morphologically similar at the larval and pupal stages. Chromosomally, these species are readily distinguished by the position of the nucleolar organizer, which is in the short arm of chromosome I in S. cauchense and in the long arm of chromosomes III in S. quadrifidum. They also differ by three fixed inversions. Sex chromosomes are undifferentiated in both species. Chromosomal resolution of the two species allowed us to evaluate four structural features previously used as diagnostic aids at the larval stage. Characters that distinguish larvae of the two species are the number of branches and branching patterns of the dorsal abdominal setae and the dark band on each primary fan. Branching patterns of the gill histoblasts were often diagnostic, with S. quadrifidum exhibiting more proximal branching and S. cauchense more distal branching. Sites where both species occurred sometimes had larvae with one petiole branching proximally and the other distally; in these cases examination of the chromosomes permitted assignment of the specimen to species. Pigmentation patterns of larvae, on the other hand, are highly variable. Color typically is sex linked in both species.