Immunopathogenic mechanisms in schistosomiasis: what can be learnt from human studies?

Studies in mice indicate that schistosome egg-induced granuloma formation and hepatic fibrosis depend markedly on cytokine regulation, with interleukin 10 having a central role. There is no clear consensus about the pattern of cytokine production and regulation that causes a minority of chronically exposed patients to develop severe hepatosplenic (HS) disease, which is characterized by periportal fibrosis and portal hypertension. HS disease and the progression of hepatic fibrosis are associated with the production of profibrotic type 2 cytokines in the early stages of infection with Schistosoma mansoni. However, other studies indicate that HS disease is characterized by a predominant T helper 1 profile. Until new tools and approaches are developed to study human disease in endemic areas, investigators must either speculate about indirect evidence from human studies or rely more heavily on findings generated from experimental models of the disease.     

Positive interactions among plant species for pollinator service: assessing the ‘magnet species’ concept with invasive species

Plants with poorly attractive flowers or with little floral rewards may have inadequate pollinator service, which in turn reduces seed output. However, pollinator service of less attractive species could be enhanced when they are associated with species with highly attractive flowers (so called ‘magnet‐species’). Although several studies have reported the magnet species effect, few of them have evaluated whether this positive interaction result in an enhancement of the seed output for the beneficiary species. Here, we compared pollinator visitation rates and seed output of the invasive annual species Carduus pycnocephalus when grow associated with shrubs of the invasive Lupinus arboreus and when grow alone, and hypothesized that L. arboreus acts as a magnet species for C. pycnocephalus. Results showed that C. pycnocephalus individuals associated with L. arboreus had higher pollinator visitation rates and higher seed output than individuals growing alone. The higher visitation rates of C. pycnocephalus associated to L. arboreus were maintained after accounting for flower density, which consistently supports our hypothesis on the magnet species effect of L. arboreus. Given that both species are invasives, the facilitated pollination and reproduction of C. pycnocephalus by L. arboreus could promote its naturalization in the community, suggesting a synergistic invasional process contributing to an ‘invasional meltdown’. The magnet effect of Lupinus on Carduus found in this study seems to be one the first examples of indirect facilitative interactions via increased pollination among invasive species.     

Studies on the production and regulation of interleukin,IL-13, IL-4 and interferon-gamma in human Schistosomiasis mansoni

The production and regulation of interleukin (IL) IL-13, IL-4 and interferon-gamma was evaluated in different clinical forms of human schistosomiasis. The mechanisms of immune regulation are apparently different in the various clinical stages of the disease, some of them being antigen specific.     

Comparison between human and armadillo Paracoccidioides brasiliensis isolates by random amplified polymorphic DNA analysis

Sixty-three Paracoccidioides brasiliensis isolates obtained from three nine-banded armadillos ( Dasypus novemcinctus), one Amazonian armadillo's and 19 clinical isolates were compared by random amplified polymorphic DNA analysis with the primer OPG-19. The isolates were divided into three major clusters, I, II and III. Coincidences between human and armadillo isolates were observed in clusters I and II. Cluster III consisted only of armadillos' isolates. The results suggested that (I) humans may acquire P. brasiliensis infection by contact with armadillo's environment, (II) there may be P. brasiliensis genotypes peculiar to the animal, and (III) individual armadillos may be infected with P. brasiliensis cells with different genotypes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Interpretation of metameric architecture in dominant shrubs of the Chilean matorral

Summary The seasonal progression of phenophases in 21 shrub species of the Chilean matorral was analyzed. Five modules or basic units that are responsible for the aboveground architecture of the plants were characterized. These modules appear to be organized in seven different spatial arrangements. In drought-deciduous species a module type with an absolute short shoot with limited apical growth, leafy or spiny, predominated. In evergreen species long shoot and temporal leafy short shoot module types were more frequent. The spatial arrangement of morphologically different modules and the temporal sequence of their formation allow a dynamic interpretation of the modular architecture of the plants.     

A three-step molecular protocol employing DNA obtained from dried blood spots for neonatal screening for 45,X Turner syndrome

Turner syndrome (TS) is one of the most common human chromosomal abnormalities; it is characterized by the presence of one normal X chromosome and the complete or partial loss of the second X chromosome. The early recognition of TS patients allows for adequate therapy for short stature and pubertal sex steroid substitution. We developed a cost-effective molecular diagnostic tool that can be used to identify 45,X TS patients from dried blood spots, for possible use in neonatal screening for TS. We used a three-step method for 45,X TS detection: i) DNA extraction from dried blood spot samples, ii) pre-PCR HpaII digestion (methylation-sensitive enzyme) and iii) GeneScan analysis of selected cases. DAX-1 gene amplification was used to recognize DNA integrity, and the androgen receptor gene (Xq11-12), which is both a highly polymorphic and methylated gene, was used to determine the number of X chromosome alleles. Using this three-step diagnostic procedure, we detected apparent TS in 1/304 (0.33%) samples; such individuals should be submitted to clinical examination and karyotype confirmation. The three-step 45,X TS neonatal screening protocol is a simple, reliable, fast (under 30 h) and cost-effective diagnostic tool, useful for the neonatal detection of TS.     

Evidence of colonization of man-made ecotopes by Triatoma dimidiata (Latreille, 1811) in Costa Rica

Triatoma dimidiata adults have been frequently found, during the last five years, in a dog kennel and a chicken coop, in the back yard of a well-built house, 15 km from San José, the capital of Costa Rica. In the chicken coop nymphs were also found. Two of the 11 dogs from the kennel were serologically positive for Trypanosoma cruzi infection. The inhabitants of the house, three adults and two children, were negative. This type of colonization by the insect, which is attracted to lights, is becoming common in old and new settlements, with different degrees of success, a fact with epidemiological implications and great relevance in the control strategies that can be applied.     

Species Richness and Evidence of Random Patterns in Assemblages of South American Titanosauria during the Late Cretaceous (Campanian–Maastrichtian)

The Titanosauria were much diversified during the Late Cretaceous, but paleobiological information concerning these sauropods continues to be scarce and no studies have been conducted utilizing modern methods of community analysis to infer possible structural patterns of extinct assemblages. The present study sought to estimate species richness and to investigate the existence of structures in assemblages of the South American Titanosauria during the Late Cretaceous. Estimates of species richness were made utilizing a nonparametric estimator and null models of species co-occurrences and overlapping body sizes were applied to determine the occurrence of structuring in this assemblages. The high estimate of species richness (n = 57) may have been influenced by ecological processes associated with extinction events of sauropod groups and with the structures of the habitats that provided abundant support to the maintenance of large numbers of species. The pseudocommunity analysis did not differ from that expected by chance, indicating the lack of structure in these assemblages. It is possible that these processes originated from phylogenetic inertia, associated with the occurrence of stabilized selection. Additionally, stochastic extinction events and historical factors may also have influenced the formation of the titanosaurian assemblages, in detriment to ecological factors during the Late Cretaceous. However, diagenetic and biostratinomic processes, influenced by the nature of the sedimentary paleoenvironment, could have rendered a random arrangement that would make assemblage structure undetectable.     

Phylogenetic structure of Neotropical annual fish of the genus Cynopoecilus (Cyprinodontiformes: Rivulidae), with an assessment of taxonomic implications

The definition of species boundaries constitutes an important challenge in biodiversity studies. Cynopoecilus Regan, 1912 encompasses several endangered species of annual fish, occurring in temporary ponds in a restricted area of Southern Brazil and Uruguay. Divergences about the taxonomic status of Cynopoecilus species highlight the importance of species delimitation studies. Therefore, we address here the phylogenetic structure of Cynopoecilus, while assessing its taxonomic implications. For this, fragments of the mitochondrial COI and nuclear RAG1 genes were characterized and analyzed for a set of 275 and 280 specimens, respectively. DNA barcoding and phylogenetic analyses detected subdivision of these specimens in 8–10 clusters, which comprise the six previously described species, and suggest one invalid taxon and at least 3–5 putative new species. The phylogenetic structure also suggests that the Jacuí River and the Patos Lagoon historically acted as effective barriers to gene flow between populations, although some isolated dispersal events across these water bodies could be evidenced, especially for C. melanotaenia Regan, 1912. In general, the results highlight the need of independent conservation strategies within the distribution area of each of the endemic allopatric killifish clusters, while questioning several taxonomic boundaries and distribution data.