Lagochilascaris minor third-stage larvae secrete metalloproteases with specificity for fibrinogen and native collagen

Dissemination of parasitic infections depends on migration through tissues and evasion from both hemostatic processes and immune responses from hosts. Metalloproteases play major roles in these mechanisms of pathogen-host interactions and, thus, are considered drug targets. In this study, we characterized metalloprotease activities in excretory/secretory (ES) products from third stage larvae (L3) of the ascarid Lagochilascaris minor, the causative agent of lagochilascariosis, which demonstrates an impressive migrating capacity across host tissues, including bone. Gel enzymography showed that ES products of L3 display two major gelatinolytic activities. Optimal proteolytic activity was found to occur at neutral/alkaline pH and was associated with two L. minor-secreted metalloproteases of 59 (SM59(Lm)) and 114kDa (SM114(Lm)). We next showed that ES products of L3 were able to hydrolyze fibrinogen and collagen I at neutral pH, but not BSA, in an extensive manner. Furthermore, we demonstrated that ES products of L3 mediate hydrolysis of the triple helical structure of collagen I fibers in mouse mesentery. These results suggest that ES proteases of L3 might facilitate both L. minor migration through host tissues by hydrolyzing collagens of the extracellular matrix and evasion from host hemostatic mechanisms by degrading fibrinogen.     

Dynamics of fine root carbon in Amazonian tropical ecosystems and the contribution of roots to soil respiration

Radiocarbon (¹⁴C) provides a measure of the mean age of carbon (C) in roots, or the time elapsed since the C making up root tissues was fixed from the atmosphere. Radiocarbon signatures of live and dead fine (<2 mm diameter) roots in two mature Amazon tropical forests are consistent with average ages of 4–11 years (ranging from <1 to >40 years). Measurements of ¹⁴C in the structural tissues of roots known to have grown during 2002 demonstrate that new roots are constructed from recent (<2‐year‐old) photosynthetic products. High Δ¹⁴C values in live roots most likely indicate the mean lifetime of the root rather than the isotopic signature of inherited C or C taken up from the soil. Estimates of the mean residence time of C in forest fine roots (inventory divided by loss rate) are substantially shorter (1–3 years) than the age of standing fine root C stocks obtained from radiocarbon (4–11 years). By assuming positively skewed distributions for root ages, we can effectively decouple the mean age of C in live fine roots (measured using ¹⁴C) from the rate of C flow through the live root pool, and resolve these apparently disparate estimates of root C dynamics. Explaining the ¹⁴C values in soil pore space CO₂, in addition, requires that a portion of the decomposing roots be cycled through soil organic matter pools with decadal turnover time.     

Seasonal changes in chlorophyll distributions in Amazon floodplain lakes derived from MODIS images

To assess seasonal changes in phytoplanktonic chlorophyll distributions in Amazon floodplain lakes, a linear mixing model was applied to Moderate Resolution Imaging Spectroradiometer (MODIS) reflectance data acquired at four river stages: rising (April), high (June), decreasing (September), and low (November). The study area is located in a floodplain reach from Parintins (Amazonas) to near Almeirim (Pará). A three-end-member mixing model designed to uncouple three fractions [high suspended inorganic matter (ip), low inorganic suspended matter (w), and high chlorophyll a (Chl)] was tested in Lake Curuaí (1.5°S 55.43°W) based on field sampling done almost concurrently with satellite overpasses. During high water, phytoplankton patches are confined to lakes closer to terra firme under the influence of clear water inflow, whereas during the low and decreasing water stages, the patches are more evenly distributed over the floodplain.     

Tree species composition and diversity gradients in white-water forests across the Amazon Basin

Aim Attention has increasingly been focused on the floristic variation within forests of the Amazon Basin. Variations in species composition and diversity are poorly understood, especially in Amazonian floodplain forests. We investigated tree species composition, richness and α diversity in the Amazonian white‐water (várzea) forest, looking particularly at: (1) the flood‐level gradient, (2) the successional stage (stand age), and (3) the geographical location of the forests. Location Eastern Amazonia, central Amazonia, equatorial western Amazonia and the southern part of western Amazonia. Methods The data originate from 16 permanent várzea forest plots in the central and western Brazilian Amazon and in the northern Bolivian Amazon. In addition, revised species lists of 28 várzea forest inventories from across the Amazon Basin were used. Most important families and species were determined using importance values. Floristic similarity between plots was calculated to detect similarity variations between forest types and over geographical distances. To check for spatial diversity gradients, α diversity (Fisher) of the plots was correlated with stand age, longitudinal and latitudinal plot location, and flood‐level gradient. Results More than 900 flood‐tolerant tree species were recorded, which indicates that Amazonian várzea forests are the most species‐rich floodplain forests worldwide. The most important plant families recorded also dominate most Neotropical upland forests, and c. 31% of the tree species listed also occur in the uplands. Species distribution and diversity varied: (1) on the flood‐level gradient, with a distinct separation between low‐várzea forests and high‐várzea forests, (2) in relation to natural forest succession, with species‐poor forests in early stages of succession and species‐rich forests in later stages, and (3) as a function of geographical distance between sites, indicating an increasing α diversity from eastern to western Amazonia, and simultaneously from the southern part of western Amazonia to equatorial western Amazonia. Main conclusions The east‐to‐west gradient of increasing species diversity in várzea forests reflects the diversity patterns also described for Amazonian terra firme. Despite the fine‐scale geomorphological heterogeneity of the floodplains, and despite high disturbance of the different forest types by sedimentation and erosion, várzea forests are dominated by a high proportion of generalistic, widely distributed tree species. In contrast to high‐várzea forests, where floristic dissimilarity increases significantly with increasing distance between the sites, low‐várzea forests can exhibit high floristic similarity over large geographical distances. The high várzea may be an important transitional zone for lateral immigration of terra firme species to the floodplains, thus contributing to comparatively high species richness. However, long‐distance dispersal of many low‐várzea trees contributes to comparatively low species richness in highly flooded low várzea.     

Isolation, Characterization, and Transcriptional Analysis of the Chitinase chi2 Gene (DQ011663) from the Biocontrol Fungus Metarhizium anisopliae var. anisopliae

Metarhizium anisopliae infects arthropods via a combination of specialized structures and cuticle degradation. Hydrolytic enzymes are accepted as key factors for the host penetration step and include chitinases. The characterization of the chi2 chitinase gene from M. anisopliae var. anisopliae is reported. The chi2 gene is interrupted by two short introns and is 1,542-bp long, coding a predicted protein of 419 amino acids with a stretch of 19 amino acid residues displaying characteristics of signal peptide. The predicted chitinase molecular mass is 44 kDa with a mature protein of 42 kDa and a theoretical pI of 4.8. The comparison of the CHI2 predicted protein to fungal orthologues revealed similarity to the glycohydrolase family 18 and a phylogenetic analysis was conducted. The chi2 gene is up-regulated by chitin as a carbon source and in conditions of fungus autolysis, and is down-regulated by glucose. This regulation is consistent with the presence of putative CreA/Crel/Crr1 carbon catabolic repressor binding domains on the regulatory sequence.     

Cadinane sesquiterpenoids of Phomopsis cassiae, an endophytic fungus associated with Cassia spectabilis (Leguminosae)

Five cadinane sesquiterpenes derivatives were isolated by bioassay-guided fractionation from Phomopis cassiae, an endophytic fungus isolated from Cassia spectabilis. The structures of the two diastereoisomeric 3,9,12-trihydroxycalamenenes (1, 2); 3,12-dihydroxycalamenene (3); 3,12-dihydroxycadalene (4) and 3,11,12-trihydroxycadalene (5) were established on the basis of analyses of 1D and 2D NMR and HRTOFMS experiments. Antifungal activity of the isolates was evaluated against Cladosporium sphaerospermum and Cladosporium cladosporioides, revealing 5 as the most active compound.     

The effect of Bulgarian propolis against Trypanosoma cruzi and during its interaction with host cells

Propolis has shown activity against pathogenic microorganisms that cause diseases in humans and animals. The ethanol (Et-Blg) and acetone (Ket-Blg) extracts from a Bulgarian propolis, with known chemical compositions, presented similar activity against tissue culture-derived amastigotes. The treatment of Trypanosoma cruzi-infected skeletal muscle cells with Et-Blg led to a decrease of infection and of the intracellular proliferation of amastigotes, while damage to the host cell was observed only at concentration 12.5 times higher than those affecting the parasite. Ultrastructural analysis of the effect of both extracts in epimastigotes revealed that the main targets were the mitochondrion and reservosomes. Et-Blg also affected the mitochondrion-kinetoplast complex in trypomastigotes, offering a potential target for chemotherapeutic agents.     

Cell proliferation and interferon-gamma response to recombinant MBP-3, NarL, MT-10.3, and 16 kDa Mycobacterium tuberculosis antigens in Brazilian tuberculosis patients

Human pulmonary tuberculosis (TB) is a worldwide public health problem. In resistant individuals, control of the infection mainly requires development of a Th1 cell immune response with production of cytokines, of which interferon-gamma (IFN-gamma)plays an important role. Several antigens from Mycobacterium tuberculosis complex has been described for use in vaccine development or for diagnostic purposes, however little evaluation has been done in endemic area for TB. The proliferative and IFN-gamma human T cell immune responses, to four recombinant proteins (MBP-3, NarL, MT-10.3, 16 kDa) and PPD, of 38 Brazilian TB patients (6 untreated and 32 treated) and 67 controls (38 positive and 29 negative tuberculin skin test - TST) were compared. The highest reactivity mean rate was obtained with PPD followed by 16 kDa in TB patients. While most of the patients (87%) and controls (> 64%) respond to the PPD, 16 kDa was more specifically recognized (> 21%) although less sensitive (54%). When TB patients were divided according to treatment status, opposite to PPD, higher average level of IFN-gamma was induced by 16 kDa in untreated (505 pg/ml) compared to treated TB patients and TST+ (269.8 pg/ml x 221.6 pg/ml, respectively), although the difference was not significant. These data show that in contrast with the other recombinant proteins, the stimulatory potency of 16 kDa to induce proliferative and INF-gamma response was more effective and is more recognized by active TB untreated patients, eliciting in control individuals a more selective immune response than PPD.     

Hepatic stereology of Schistosomiasis mansoni infected-mice fed a high-fat diet

High-fat diets induce weight gain and fatty liver in wild-type mice. Schistosomiasis mansoni infection also promotes hepatic injury. This study was designed to quantify hepatic alterations in schistosomiasis mansoni-infected mice fed a high fat-rich chow compared to mice fed a standard rodent chow, using stereology. Female SW mice fed each either high-fat diet (29% lipids) or standard chow (12% lipids) over 8 months, and then were infected with Schistosoma mansoni cercariae. Four experimental groups were studied: infected mice fed a high-fat diet (IHFC) or standard chow (ISC), uninfected mice fed a high-fat diet (HFC) or standard chow (SC). Mice were sacrificed during early infection (9 weeks from exposure). The following hepatic biometry and the stereology parameters were determined: volume density (hepatocytes [h], sinusoids [s], steatosis [st] and hepatic fibrosis [hf]); numerical density (hepatocyte nuclei - Nv[h]); absolute number of total hepatocyte N[h], normal hepatocyte N[nh], and binucleated hepatocyte N[bh], percentage of normal hepatocyte P[nh] and binucleated hepatocyte P[bh]. IHFC and HFC groups exhibited TC, HDL-C, LDL-C, and body mass significantly greater (p < 0.05) than control group. No significant differences were found regards liver volume (p = 0.07). Significant differences were observed regards P[nh] (p = 0.0045), P[bh] (p = 0.0045), Nv[h] (p = 0.0006), N[h] (p = 0.0125), N[bh] (p = 0.0164) and N[nh] (p = 0.0078). IHFC mice group presented 29% of binucleated hepatocytes compared to HFC group (19%), ISC group (17%) and SC (6%). Volume density was significantly different between groups: Vv[h] (p = 0.0052), Vv[s] (p = 0.0025), Vv[st] (p = 0.0004), and Vv[hf] (p = 0.0007). In conclusion, schistosomiasis mansoni infection with concurrent high-fat diet promotes intensive quantitative changes in hepatic structure, contributing to an increasing on hepatic regeneration.     

Clinical-epidemiological profile of children with schistosomal myeloradiculopathy attended at the Instituto Materno-Infantil de Pernambuco

The most critical phase of exposure to schistosomal infection is the infancy, because of the more frequent contact with contaminated water and the immaturity of the immune system. One of the most severe presentations of this parasitosis is the involvement of the spinal cord, which prognosis is largely dependent on early diagnosis and treatment. Reports on this clinical form of schistosomiasis in children are rare in the literature. We present here the clinical-epidemiological profile of schistosomal myeloradiculopathy (SMR) from ten children who were admitted at the Instituto Materno-Infantil de Pernambuco over a five-year period. They were evaluated according to an investigation protocol. Most of these patients presented an acute neurological picture which included as the main clinical manifestations: sphincteral disorders, low back and lower limbs pain, paresthesia, lower limbs muscle weakness and absence of deep tendon reflex, and impairment of the gait. The diagnosis was presumptive in the majority of the cases. This study emphasizes the importance of considering the diagnosis of SMR in pediatric patients coming from endemic areas who present a low cord syndrome, in order to start the appropriate therapy and avoid future complications.