Copepods of the Juréia ecological reserve,state of São Paulo,Brazil. II. The genera Hesperocyclops,Muscocyclops, and Bryocyclops (Cyclopoida,Cyclopidae)

Cyclopid copepods collected mainly in aquatic microcosms and semiterrestrial habitats in the Juréia Ecological Reserve are studied. Hesperocyclops herbsti and Bryocyclops campaneri are described as new species and their taxonomical relationships discussed. Females of Muscocyclops operculatus (Chappuis) are redescribed and the males described for the first time. An emended diagnosis for Muscocyclops is proposed.     

Short-term effects of a large dam decommissioning on biofilm structure and functioning

Aging dams and the rising efforts to restore stream ecosystems are increasing the number of dam decommissioning programs. Although dam decommissioning aims at improving in-stream habitat, biodiversity, and ecosystem functioning in the long term, it might also cause ecological impacts in the short term due to the mobilization of the sediment accumulated in the reservoir. Benthic biofilm in particular can be impaired by episodes of high turbidity and scouring. We conducted a multiple before-after/control-impact experiment to assess the effects of the drawdown of a large dam (42 m tall), a first step to its decommissioning, on biofilm structure (biomass and chlorophyll-a) and functioning (metabolism, nutrient uptake, and organic matter breakdown). Our results show that the reservoir drawdown reduced the autotrophic biofilm biomass (chlorophyll-a) downstream from the dam, which in turn lowered metabolism. However, nitrogen and phosphorus uptake by the biofilm was not affected. Organic matter breakdown was slower below the dam than in nearby undammed reaches before and during drawdown. All drawdown effects quickly disappeared and reaches downstream from the dam approached values found in nearby undammed reaches. Thus, our results indicate that the effects of reservoir drawdown on stream biofilms exist but may be small and disappear rapidly.     

Casearia Essential Oil: An Updated Review on the Chemistry and Pharmacological Activities

Casearia species are found in the America, Africa, Asia, and Australia and present pharmacological activities, besides their traditional uses. Here, we reviewed the chemical composition, content, pharmacological activities, and toxicity of the essential oils (EOs) from Casearia species. The EO physical parameters and leaf botanical characteristics were also described. The bioactivities of the EOs from the leaves and their components include cytotoxicity, anti-inflammatory, antiulcer, antimicrobial, antidiabetic, antioxidant, antifungal, and antiviral activities. The main components associated with these activities are the α-zingiberene, (E)-caryophyllene, germacrene D, bicyclogermacrene, spathulenol, α-humulene, β-acoradiene, and δ-cadinene. Data on the toxicity of these EOs are scarce in the literature. Casearia sylvestris Sw. is the most studied species, presenting more significant pharmacological potential. The chemical variability of EOs components was also investigated for this species. Caseria EOs have relevant pharmacological potential and must be further investigated and exploited.     

Interplay between the RNA binding‐protein Musashi and developmental signaling pathways

Musashi comprises an evolutionarily conserved family of RNA‐binding proteins (RBP) that regulate cell fate decisions during embryonic development and play key roles in the maintenance of self‐renewal and differentiation of stem cells and adult tissues. More recently, several studies have shown that any dysregulation of MSI1 and MSI2 can lead to cellular dysfunctions promoting tissue instability and tumorigenesis. Moreover, several reports have characterized many molecular interactions between members of the Musashi family with ligands and receptors of the signaling pathways responsible for controlling normal embryonic development: Notch, Transforming Growth Factor Beta (TGF‐β), Wingless (Wnt) and Hedgehog Signaling (Hh); all of which, when altered, are strongly associated with cancer onset and progression, especially in pediatric tumors. In this context, the present review aims to compile possible cross‐talks between Musashi proteins and members of the above cited molecular pathways for which dysregulation plays important roles during carcinogenesis and may be modulated by these RBP.     

Structural Basis for the Interaction of the Golgi-Associated Retrograde Protein Complex with the t-SNARE Syntaxin 6

1. Download : Download high-res image (312KB)
2. Download : Download full-size image

     

The role of floral structure and biotic factors in determining the occurrence of florivorous thrips in a dystilous shrub

Elucidating the factors determining the occurrence of florivorous organisms is an essential step for comprehending arthropod–plant interactions, especially when considering florivores that use flowers/inflorescences as microhabitats. In this study, we characterize the interaction between florivorous thrips (Thysanoptera) and Palicourea rigida (Rubiaceae), a distylous hummingbird-pollinated shrub. We investigated the relative role of different factors in determining thrips occurrence in the flower and inflorescence microhabitats. Furthermore, we experimentally examined the protective role of corolla influencing thrips exploration of floral buds. Frankliniella musaeperda (Thripidae) was the only species recorded on P. rigida, feeding on floral tissue, pollen and nectar. Thrips occurrence was not related to distyly, but rather to floral stage. Open flowers presented the highest abundance of thrips, followed by senescent flowers and then buds. The experimental opening of buds translated in increased thrips occurrence, indicating that F. musaeperda manage to explore the microhabitat offered by the floral chamber, as long as there is an opening in the corolla. In inflorescences, thrips abundance was negatively related to the number of ants visiting extrafloral nectaries. We found that the marked difference between floral morphs of distylous plants is not necessarily reflected in the abundance of florivores. Thrips seek for floral cavities, preferentially those with fresh tissue, which may confer nutrient-rich food and protection. Buds also provide this; however, the enclosed petals are an effective barrier against F. musaeperda entrance. At inflorescence scale, presence of mutualistic ants in high numbers can drive away these flower-feeding insects. Despite the abundance of thrips in the flowers, there was no evidence of any functional relationship, either of pollination for flowers or of breeding for insects. We demonstrate here that in the flower/inflorescence microhabitat, structural and biotic factors play a key role in the exploitation and occupation by insect florivores.     

Habitat Complexity in Aquatic Microcosms Affects Processes Driven by Detritivores

Habitat complexity can influence predation rates (e.g. by providing refuge) but other ecosystem processes and species interactions might also be modulated by the properties of habitat structure. Here, we focussed on how complexity of artificial habitat (plastic plants), in microcosms, influenced short-term processes driven by three aquatic detritivores. The effects of habitat complexity on leaf decomposition, production of fine organic matter and pH levels were explored by measuring complexity in three ways: 1. as the presence vs. absence of habitat structure; 2. as the amount of structure (3 or 4.5 g of plastic plants); and 3. as the spatial configuration of structures (measured as fractal dimension). The experiment also addressed potential interactions among the consumers by running all possible species combinations. In the experimental microcosms, habitat complexity influenced how species performed, especially when comparing structure present vs. structure absent. Treatments with structure showed higher fine particulate matter production and lower pH compared to treatments without structures and this was probably due to higher digestion and respiration when structures were present. When we explored the effects of the different complexity levels, we found that the amount of structure added explained more than the fractal dimension of the structures. We give a detailed overview of the experimental design, statistical models and R codes, because our statistical analysis can be applied to other study systems (and disciplines such as restoration ecology). We further make suggestions of how to optimise statistical power when artificially assembling, and analysing, ‘habitat complexity’ by not confounding complexity with the amount of structure added. In summary, this study highlights the importance of habitat complexity for energy flow and the maintenance of ecosystem processes in aquatic ecosystems.