Genetic Manipulation of Schistosoma haematobium, the Neglected Schistosome

More people are infected with Schistosoma haematobium than other major human schistosomes yet it has been less studied because of difficulty in maintaining the life cycle in the laboratory. S. haematobium might be considered the ‘neglected schistosome’ since minimal information on the genome and proteome of S. haematobium is available, in marked contrast to the other major schistosomes. In this report we describe tools and protocols to investigate the genome and genetics of this neglected schistosome. We cultured developmental stages of S. haematobium, and investigated the utility of introducing gene probes into the parasites to silence two model genes. One of these, firefly luciferase, was a reporter gene whereas the second was a schistosome gene encoding a surface protein, termed Sh-tsp-2. We observed that both genes could be silenced – a phenomenon known as experimental RNA interference (RNAi). These findings indicated that the genome of S. haematobium will be amenable to genetic manipulation investigations designed to determine the function and importance of genes of this schistosome and to investigate for novel anti-parasite treatments

Adaptive Developmental Delay in Chagas Disease Vectors: An Evolutionary Ecology Approach

The developmental time of vector insects is important to their population dynamics, evolutionary biology, epidemiology of the diseases they transmit, and to their responses to global climatic change. In various triatomine species vectors of Chagas disease (Triatominae, Reduviidae), a delay in the molt of a small proportion of individuals has been observed, and from an evolutionary ecology approach, we propose the hypothesis that the developmental delay is an adaptation to environmental stochasticity through a spreading of risk (bet-hedging) diapause strategy. We confirmed, by means of a survey among specialists, the existence of the developmental delay in triatomines. Statistical descriptions of the developmental time of 11 species of triatomines showed some degree of bi-modality in nine of them. We predicted by means of an optimization model which genotype, coding for a given frequency of developmental diapause, is expected to evolve. We identified a series of parameters that can be measured in the field and in the laboratory to test the hypothesis of an optimal diapause frequency. We also discuss the importance of these findings for triatomines in terms of global climatic change and epidemiological consequences such as their resistance to insecticides

Dual Nucleophilic/Electrophilic Capture of In Situ Generated Iminium Ethers: Towards the Synthesis of Functionalized Amide Building Blocks

The transformation of simple linear amides into a diverse range of branched, functionalized products by conversion to iminium esters is followed by sequential treatment with nucleophiles and electrophiles (see scheme). The method takes advantage of a novel Claisen rearrangement and the use of aromatic substrates greatly facilitates the formation of the intermediate iminium ether

Descrição de ovos e ninfas de Triatoma klugi (Hemiptera, Reduviidae, Triatominae) Description of eggs and nymphs of Triatoma klugi (Hemiptera, Reduviidae, Triatominae)

Os autores descreveram as características morfológicas de Triatoma klugi Carcavallo, Jurberg, Lent & Galvão, 2001 pertencente ao grupo de espécies que compõem o "complexo T. oliveirai". Até o presente tem sido difícil separar essas espécies com base nas características ninfais, o que justifica o desenvolvimento deste trabalho. Os espécimes foram coletados em frestas de rochas no morro Malavok na localidade de Linha Brasil, município de Nova Petrópolis, no Estado do Rio Grande do Sul. O local de captura dos triatomíneos situa-se entre 700 e 800 m de altitude (29º18'38''S, 51º04'57''W). Juntamente com T. oliveirai (Neiva, Pinto & Lent, 1939), espécie morfologicamente mais próxima, são as únicas do complexo que não foram encontradas, até o momento, no Estado do Mato Grosso, Mato Grosso do Sul e Goiás, Brasil. Em condições experimentais, já foi testada e comprovada a sua susceptibilidade à infecção pelo Trypanosoma cruzi (Chagas, 1909) e Trypanosoma rangeli (Tejera, 1920). A análise comparativa das ornamentações do exocório dos ovos e de três estádios ninfais de T. klugi por microscopia óptica e microscopia eletrônica de varredura mostrou algumas particularidades morfológicas, com destaque para: a face ventral da cabeça, o sulco estridulatório e os últimos segmentos abdominais (IX, X - futura genitália e XI - tubo anal). Esses dados contribuem para a ampliação dos parâmetros diferenciais visando à diagnose de T. klugi durante o seu desenvolvimento ninfal.<br>The authors had described the morphologic characteristics of Triatoma klugi Carcavallo, Jurberg, Lent & Galvão, 2001 to the group of species belonging to "T. oliveirai complex". Until the moment it has been difficult to separate on the nymphs characteristics basis these species, what it justifies the development of this work. The specimens had been collected in openings of rocks in the Malavok mount in the locality of Linha Brazil, city of Nova Petrópolis, in the State of Rio Grande do Sul. The local of capture of the Triatominae is placed enters 700 and 800 m of altitud (29º18'38''S, 51º04'57''W). Together with T. oliveirai (Neiva, Pinto & Lent, 1939), its morphologically related species, is the only ones of the complex that had not been found, until the moment, in the State of Mato Grosso, Mato Grosso do Sul and Goiás, Brazil. In experimental conditions, already it was tested and proven its susceptibilities to the infection for Trypanosoma cruzi (Chagas, 1909) and Trypanosoma rangeli (Tejera, 1920). The comparative analysis of the ornaments of the exocorium of eggs and of three nymphs of T. klugi by optic microscopy and scanning electron microscopy showed some morphologic particularities, with prominence for: the ventral face of the head, the stridulatory sulcus and the last abdominal segments (IX, X - future genitalia and XI - anal duct). These data contribute for the magnifying of the distinguishing parameters aiming at diagnosis of T. klugi during its nymphal development