Cestode strobilation: prediction of developmental genes and pathways

Background: Cestoda is a class of endoparasitic worms in the flatworm phylum (Platyhelminthes). During the course of their evolution cestodes have evolved some interesting aspects, such as their increased reproductive capacity. In this sense, they have serial repetition of their reproductive organs in the adult stage, which is often associated with external segmentation in a developmental process called strobilation. However, the molecular basis of strobilation is poorly understood. To assess this issue, an evolutionary comparative study among strobilated and non-strobilated flatworm species was conducted to identify genes and proteins related to the strobilation process. Results: We compared the genomic content of 10 parasitic platyhelminth species; five from cestode species, representing strobilated parasitic platyhelminths, and five from trematode species, representing non-strobilated parasitic platyhelminths. This dataset was used to identify 1813 genes with orthologues that are present in all cestode (strobilated) species, but absent from at least one trematode (non-strobilated) species. Development- related genes, along with genes of unknown function (UF), were then selected based on their transcriptional profiles, resulting in a total of 34 genes that were differentially expressed between the larval (pre-strobilation) and adult (strobilated) stages in at least one cestode species. These 34 genes were then assumed to be strobilation related; they included 12 encoding proteins of known function, with 6 related to the Wnt, TGF-β/BMP, or G-protein coupled receptor signaling pathways; and 22 encoding UF proteins. In order to assign function to at least some of the UF genes/proteins, a global gene co-expression analysis was performed for the cestode species Echinococcus multilocularis. This resulted in eight UF genes/proteins being predicted as related to developmental, reproductive, vesicle transport, or signaling processes. Conclusions: Overall, the described in silico data provided evidence of the involvement of 34 genes/proteins and at least 3 developmental pathways in the cestode strobilation process. These results highlight on the molecular mechanisms and evolution of the cestode strobilation process, and point to several interesting proteins as potential developmental markers and/or targets for the development of novel antihelminthic drugs

Análise de redes de coexpressão de amostras do sangue periférico de pacientes com leucemia mieloide aguda

A leucemia mieloide aguda (LMA) é um tipo de tumor hematológico caracterizado pela expansão clonal de células imaturas da linhagem mieloide. É um dos tipos de leucemia que possuem uma das maiores taxas de mortalidade em virtude da rápida disseminação no microambiente da medula óssea e facilmente atingindo a corrente sanguínea. Sabe-se que diversos fatores que compõem um ambiente tumoral podem influenciar no desenvolvimento de uma neoplasia. Na LMA, muito tem se estudado sobre o papel das células leucêmicas em modular o microambiente da medula óssea com o intuito de garantir sua capacidade proliferativa. Contudo, pouco se sabe sobre como os fatores que permeiam o ambiente do sangue periférico auxiliam estas mesmas células na sobrevivência e no seu crescimento tumoral. Logo, o objetivo deste trabalho é de observar as principais células e elementos presentes na corrente sanguínea que estão associados à sobrevivência das células leucêmicas neste contexto celular, bem como avaliar, nessas mesmas células, o perfil transcritômico (extraídas do sangue periférico de pacientes com LMA) por meio de análises de redes de coexpressão. Os resultados obtidos indicam que uma alta porcentagem de blastos CD34+ na corrente sanguínea são indicativos de mau prognóstico por modularem a resposta imune, inibindo a ação de células T efetoras e NK, por exemplo, além de promoverem a manutenção do seu estado indiferenciado e sua proliferação.Acute myelogenous leukemia (AML) is a hematological malignancy characterized by the clonal expansion of immature myeloid cells. It is one of leukemia types that has the highest mortality rates, mainly due to its fast dissemination in the bone marrow microenvironments, reaching easily the peripheral bloodstream. It is known that many factors that encompass the tumor environment can influence the tumor development. In AML, much has been studied about the role of leukemic cells in modulating the bone marrow microenvironment to guarantee its growth. However, little is known about how bloodstream factors can help these cells in the survival and proliferation. Therefore, this work aims to describe the main cells and other factors inside the bloodstream that are related to leukemic cells survival in this cellular context, as well as to evaluate, in these same cells, the transcriptomic profile of AML cells (extracted from the peripheral blood of AML patients) through a network coexpression analysis. The results indicate that the high percentage of circulating CD34+ blasts are indicative of bad prognosis due their ability to modulate the immune response, inhibiting NK and/or effector T cells anti-leukemic roles, besides promoting the maintenance of the undifferentiated and their proliferative status

Análise proteômica comparativa de Listeria monocytogenes exposta a concentrações subletais de nisina

Infecções por Listeria monocytogenes têm sido frequentemente relatadas em vários casos de surtos de infecção alimentar pelo mundo. Logo, a preocupação em tornar produtos alimentares de larga escala livres destes patógenos tem aumentado ao longo dos anos. Uma das estratégias mais eficazes são a utilização de bacteriocinas como agentes conservantes, prevenindo a multiplicação bacteriana durante os processos de fabricação, estocagem e distribuição dos produtos. A nisina é uma das bacteriocinas mais conhecidas, sendo empregada na indústria alimentícia por muitos anos. Seu mecanismo de atividade antimicrobiana principal é através da formação de um complexo, juntamente com um precursor de parede celular (lipídio II), que formam poros na membrana celular, causando o extravasamento de conteúdos celulares vitais e a perda de estabilidade eletrolítica, levando à morte celular. Entretanto, algumas evidências apontam para mecanismos alternativos, mas ainda desconhecidos, de morte celular. Uma das abordagens interessantes é por meio da análise dos processos celulares (comparado a uma condição não tratada com nisina) através de metodologias proteômicas. Os cultivos bacterianos foram tratados com concentrações subletais de nisina e os extratos proteicos foram processados em espectrometria de massas em tandem acoplado a um sistema de cromatografia líquida (LC-MS/MS). Os resultados mostraram expressão diferencial de algumas proteínas que atuam contra o estresse oxidativo, como a catalase e proteínas de armazenamento de íons ferrosos. Também verificou-se a superexpressão de uma HSP, a qual pode alterar o dobramento correto de algumas proteínas como a de divisão celular FtsZ. Por fim, a subexpressão de uma chaperona responsável pelo correto dobramento das penicillin binding proteins (PBPs) e a superexpressão de enzimas responsáveis pela síntese de lipídios precursores da membrana celular podem apontar para um sistema de divisão celular alternativo, agindo provavelmente como uma resposta à presença de membranas cobertas por complexos nisina e lipídio II.Listeria monocytogenes infections have been frequently reported in many food poisoning outbreaks around the world. Therefore, the concern about protecting largely-scale food products from these pathogens has been rising over the years. One of the most efficient strategies is using bacteriocins as a conserving agent, preventing the growth of pathogenic bacteria during the production, storage and distribution of the product. Nisin is a well-known bacteriocin, which has been applied in the food industry for many years. Its main antimicrobial mechanism is based in forming a cell membrane pore creator complex, which coupled with a cell wall precursor (lipid II), leads to the leakage of essential cell life compounds and the loss of electrolytic stability, causing the cell death. However, recent evidences lead to an alternative, but still unknown, cell death mechanism. One interesting approach is analyzing the cell processes (compared to a non-nisin treated condition) by a proteomic approach. The L. monocytogenes cells were treated with a sublethal concentration of nisin and the protein extracts were ran through a tandem mass spectrometry attached to a liquid chromatography system (LC-MS/MS). The results showed differential expression of some agents against oxidative stress such as catalase and ferrous ions storage proteins. Furthermore, it had also presented upregulation of a HSP which can alter the correct folding of other proteins, such as the FtsZ cell division protein. Finally, the downregulation of a chaperone that is responsible of the correct folding of penicillin binding proteins (PBPs) and the superexpression of some enzymes related to the production of cell membrane lipids could point out to a different bacterial cell division system, acting probably as a response to the nisin-lipid II complexes covered cell membranes

Supporting data for comparative proteomic analysis of Listeria monocytogenes ATCC 7644 exposed to a sublethal concentration of nisin

Here we provide the LC–MS/MS data from a comparative analysis of Listeria monocytogenes ATCC 7644 treated and non-treated with a sublethal concentration of nisin (10−3 mg/mL). Protein samples were analyzed by multidimensional protein identification technology (MudPIT) approach, in an off-line configuration. The raw MS/MS data allowed the detection of 49,591 spectra which resulted in 576 protein identifications. After Scaffold validation, 179 proteins were identified with high confidence. A label-free quantitative analysis based of normalized spectral abundance factor (NSAF) was used and 13 proteins were found differentially expressed between nisin-treated and non-treated cells. Gene ontology analysis of differentially expressed proteins revealed that most of them are correlated to metabolic process, oxidative stress response mechanisms and molecular binding. A detailed analysis and discussion of these data may be found in Miyamoto et al. [1]