Gall-forming and free-feeding herbivory along vertical gradients in a lowland tropical rainforest: the importance of leaf sclerophylly

In contrast to most insect guilds, gall-forming insects are thought to reach highest diversity on sclerophyllous vegetation, such as Neotropical savannas and Mediterranean vegetation types. The water and nutrient stress endured by meristems of canopy trees in tall wet tropical rainforests may cause leaf sclerophylly. Hence, the upper canopies of such ecosystems may represent a suitable habitat for gall-forming insects. At the San Lorenzo Protected Area, Panama, we estimated free-feeding herbivory and gall densities within five sites in 2003 and 2004, by surveying leaves in vertical and horizontal transects. In each sample, we recorded leaf density (mature and young foliage), free-feeding herbivore damage and number of galls, including the presence of live larvae, parasitoids or fungi. We surveyed 43 994 leaves, including 231 plants and 73 tree and liana species. We collected 5014 galls from 17 host-plant species, including 32 gall species of which 59% were restricted to the canopy (overall infestation rates: 2.4% in 2003, 5.5% in 2004). In 2003, 16% of the galls were occupied by live larvae, against 5% in 2004. About 17–20% of leaves surveyed suffered from free-feeding herbivory. Leaf sclerophylly increased significantly with sampling height, while free-feeding herbivory decreased inversely. Conversely, the number of live galls collected in the canopy was 13–16 times higher than in the understorey, a pattern consistent across sites and years. Hence, the probability of gall survivorship increased with increasing leaf sclerophylly as death by fungi, parasitoids or accidental chewing were greater in the understorey. Increasing harsh ecophysiological conditions towards the upper canopy appear favourable to galls-forming population maintenance, in support of the hypothesis of harsh environment. Hence, gall diversity and abundance in the upper canopy of tall tropical forests are perhaps among the highest in the world.     

Failure of the Amblyomma cajennense nymph to become infected by Theileria equi after feeding on acute or chronically infected horses

Tick-borne diseases in horses are caused by the intraerythrocytic protozoan parasites Theileria equi and Babesia caballi. Although T. equi is highly endemic in Latin America, the New World vector of this important parasite is controversial. The aim of this study was to test the ability of nymph Amblyomma cajennense ticks acquire infection by T. equi following feeding on infected horses. Three experiments were performed: tick acquisition of T. equi from an experimentally infected horse, tick acquisition of T. equi from naturally infected foals and tick acquisition of T. equi from a chronically infected horse. A. cajennense adults were dissected and salivary glands were collected in aliquots. Methyl green pyronin staining of the salivary glands did not show the presence of hypertrophy of acini or cell nuclei normally suggestive of Theileria spp. infection. The pools of salivary glands were negative for Theileria DNA in nested PCR assays. Histopathological analysis failed to detect sporoblast and sporozoites of T. equi in salivary gland acini. This study was not able to observe infection of the A. cajennense by T. equi.     

Flow cytometry as a tool for analyzing changes in Plasmodium falciparum cell cycle following treatment with indol compounds

Melatonin and its derivatives modulate the Plasmodium falciparum and Plasmodium chabaudi cell cycle. Flow cytometry was employed together with the nucleic acid dye YOYO-1 allowing precise discrimination between mono- and multinucleated forms of P. falciparum-infected red blood cell. The use of YOYO-1 permitted excellent discrimination between uninfected and infected red blood cells as well as between early and late parasite stages. Fluorescence intensities of schizont-stage parasites were about 10-fold greater than those of ring-trophozoite form parasites. Melatonin and related indolic compounds including serotonin, N-acetyl-serotonin and tryptamine induced an increase in the percentage of multinucleated forms compared to non-treated control cultures. YOYO-1 staining of infected erythrocyte and subsequent flow cytometry analysis provides a powerful tool in malaria research for screening of bioactive compounds.     

Impact of iron toxicity on oxidative metabolism in young Eugenia uniflora L. plants

In excess, iron can induce the production and accumulation of reactive oxygen species (ROS), causing oxidative stress. The objective of this work was to evaluate the impact of toxic concentrations of iron (Fe) on the antioxidative metabolism of young Eugenia uniflora plants. Forty-five-day-old plants grown in Hoagland nutrient solution, pH 5.0, were treated with three Fe concentrations, in the form of FeEDTA, during three periods of time. At the end of the treatment, the plants were harvested and relative growth rate, iron content, lipid peroxidation and enzymes and metabolites of the antioxidative metabolism were determined. Iron-treated plants showed higher iron contents, reduced relative growth rates and iron toxicity symptoms in both leaves and roots. There was an increase in lipid peroxidation with increasing Fe, only in the leaves. The enzymatic activities of superoxide dismutase (SOD) and glutathione reductase (GR) increased with increasing Fe concentration and treatment exposure time. The activities of catalase (CAT), peroxidase (POX) and ascorbate peroxidase (APX) also increased with increasing Fe concentration but decreased with increasing treatment exposure time. Glutathione peroxidase activity (GPX) decreased with increasing Fe concentration and exposure time. The ascorbate (AA) and reduced glutathione (GSH) contents and the AA/DHA and GSH/GSSG ratios, in general, increased with increasing Fe concentration and treatment exposure time. The results indicate that under toxic levels of Fe, young E. uniflora plants suffer increased oxidative stress, which is ameliorated through changes in the activities of antioxidative enzymes and in the contents of the antioxidants AA and GSH.     

Early Transplantation of Bone Marrow Mononuclear Cells Promotes Neuroprotection and Modulation of Inflammation After Status Epilepticus in Mice by Paracrine Mechanisms

Status epilepticus (SE) is a severe clinical manifestation of epilepsy associated with intense neuronal loss and inflammation, two key factors involved in the pathophysiology of temporal lobe epilepsy. Bone marrow mononuclear cells (BMMC) attenuated the consequences of pilocarpine-induced SE, including neuronal loss, in addition to frequency and duration of seizures. Here we investigated the effects of BMMC transplanted early after the onset of SE in mice, as well as the involvement of soluble factors produced by BMMC in the effects of the cell therapy. Mice were injected with pilocarpine for SE induction and randomized into three groups: transplanted intravenously with 1 × 10⁷ BMMC isolated from GFP transgenic mice, injected with BMMC lysate, and saline-treated controls. Cell tracking, neuronal counting in hippocampal subfields and cytokine analysis in the serum and brain were performed. BMMC were found in the brain 4 h following transplantation and their numbers progressively decreased until 24 h following transplantation. A reduction in hippocampal neuronal loss after SE was found in mice treated with live BMMC and BMMC lysate when compared to saline-treated, SE-induced mice. Moreover, the expression of inflammatory cytokines IL-1β, TNF-α, IL-6 was decreased after injection of live BMMC and to a lesser extent, of BMMC lysate, when compared to SE-induced controls. In contrast, IL-10 expression was increased. Analysis of markers for microglia activation demonstrated a reduction of the expression of genes related to type 1-activation. BMMC transplantation promotes neuroprotection and mediates anti-inflammatory effects following SE in mice, possibly through the secretion of soluble factors.     

Microsatellite markers for the palaeo-temperature indicator Pentapharsodinium dalei (Dinophyceae)

Pentapharsodinium dalei is a widely distributed cold-water dinoflagellate, which is used in palaeoecology as an indicator of relatively warmer conditions in polar and sub-polar regions. This species has been proposed to be one of the first indicators of global warming at high latitudes. We developed the first microsatellite markers for P. dalei to facilitate the study of spatial and temporal population genetic changes. Single cysts were isolated from surface sediments in Koljö Fjord, Sweden. After cyst germination, single vegetative cells were isolated for establishing monoclonal cultures. Six dinucleotide polymorphic microsatellite markers were developed as multiplex polymerase chain reactions and were genotyped in 32 strains. The number of alleles per locus varied between 4 and 12, and the estimated gene diversity varied from 0.588 to 0.891. The haploid state of the vegetative cells was confirmed. The six selected microsatellites will be useful to explore population dynamics in P. dalei from contemporary planktonic and revived benthic samples to enable, for example, detailed studies into the evolutionary consequences of anthropogenic and climate-driven habitat changes.     

Na+K+-ATPase Activity and K+ Channels Differently Contribute to Vascular Relaxation in Male and Female Rats

Gender associated differences in vascular reactivity regulation might contribute to the low incidence of cardiovascular disease in women. Cardiovascular protection is suggested to depend on female sex hormones’ effects on endothelial function and vascular tone regulation. We tested the hypothesis that potassium (K⁺) channels and Na⁺K⁺-ATPase may be involved in the gender-based vascular reactivity differences. Aortic rings from female and male rats were used to examine the involvement of K⁺ channels and Na⁺K⁺-ATPase in vascular reactivity. Acetylcholine (ACh)-induced relaxation was analyzed in the presence of L-NAME (100 µM) and the following K⁺ channels blockers: tetraethylammonium (TEA, 2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 µM) and charybdotoxin (ChTX, 0.1 µM). The ACh-induced relaxation sensitivity was greater in the female group. After incubation with 4-AP the ACh-dependent relaxation was reduced in both groups. However, the dAUC was greater in males, suggesting that the voltage-dependent K⁺ channel (K_v) participates more in males. Inhibition of the three types of Ca²⁺-activated K⁺ channels induced a greater reduction in R_max in females than in males. The functional activity of the Na⁺K⁺-ATPase was evaluated by KCl-induced relaxation after L-NAME and OUAincubation. OUA reduced K⁺-induced relaxation in female and male groups, however, it was greater in males, suggesting a greater Na⁺K⁺-ATPase functional activity. L-NAME reduced K⁺-induced relaxation only in the female group, suggesting that nitric oxide (NO) participates more in their functional Na⁺K⁺-ATPase activity. These results suggest that the K⁺ channels involved in the gender-based vascular relaxation differences are the large conductance Ca²⁺-activated K⁺ channels (BK_Ca) in females and K_v in males and in the K⁺-induced relaxation and the Na⁺K⁺-ATPase vascular functional activity is greater in males.