Spatial distribution of heterochromatic bodies in Triatoma infestans (Klug) and Panstrongylus megistus (Burmeister)

Orientador: Maria Luiza Silveira MelloDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Em alguns organismos animais e vegetais o posicionamento da heterocromatina constitutiva vem sendo descrito como adjacente ou muito próximo à periferia nuclear, havendo a hipótese de que alta densidade gênica ou presença de genes ativos se concentrariam mais no interior nuclear, enquanto DNA com pouca densidade gênica se posicionaria próximo à periferia nuclear. Insetos como Triatoma infestans e Panstrongylus megistus são conhecidos por apresentarem em seus núcleos cromocentros conspícuos, mas a topologia apresentada por esses corpos de heterocromatina constitutiva no interior dos núcleos não se acha ainda estabelecida. No presente trabalho investigou-se se a distribuição espacial dos cromocentros presentes nas células epiteliais de túbulos de Malpighi desses insetos seria preferencial com respeito à periferia nuclear e como se comportaria ao longo do desenvolvimento. Buscou-se também determinar se um sítio de DNA cuja expressão é vital para a sobrevivência celular, como é o rDNA 18S possivelmente localizado nos cromocentros, ocuparia posição preferencial voltada ao centro nuclear. Dados morfométricos relativos ao posicionamento dos cromocentros foram obtidos por microscopia confocal em preparados submetidos à reação de Feulgen fluorescente. A distribuição dos sítios de rDNA 18S foi estudada por microscopia confocal em preparados submetidos ao ensaio FISH, usando-se sondas espécie-específicas. Os resultados demonstraram que em ambas as espécies os cromocentros se posicionam com relativa proximidade à periferia nuclear, embora não adjacentes a esta. Tal topologia tem um caráter dinâmico, dado a variabilidade na distância entre cromocentros e periferia nuclear, sugerindo movimentação desse território cromatínico. Esta distância aumenta com o desenvolvimento ninfal, provavelmente devido à poliploidização crescente ocorrida nesses núcleos, com consequente aumento no volume de eucromatina. Embora os cromocentros aqui estudados ocupem posição não casual no interior dos núcleos e sua distribuição tenha um caráter dinâmico, não parece haver relação entre a distribuição de sítios de rDNA 18S detectada nos cromocentros, e a posição ocupada por esses corpos em relação à periferia nuclear. Uma vez que sítios de rDNA 18S foram também revelados voltados à periferia nuclear, a proximidade dos cromocentros a esta região não corresponde obrigatoriamente a silenciamento gênico nestes organismosAbstract: Some animal and plant organisms are characterized by containing constitutive heterochromatin adjacent or very close to the nuclear periphery. High gene density or presence of active genes has been hypothesized to be preferentially concentrated in the innermost region of the cell nuclei, whereas the chromatin regions that contain low gene density have been considered to be positioned close to the nuclear periphery. In nuclei from insects like Triatoma infestans and Panstrongylus megistus, vectors of Chagas disease, conspicuous chromocenters have been described. However, no information exists on whether these constitutive heterochromatin bodies acquire a precise topology in the cell nuclei. In the present work, the spatial distribution of chromocenters in the epithelial cell nuclei from Malpighian tubules of T. infestans and P. megistus was studied following the insect development. In addition, it was also investigated whether a DNA site relevant for cell survival, as is the case of the rDNA 18S, possibly present in the chromocenters, was positioned preferentially towards the nuclear center. The morphometric data necessary for establishing the chromocenter position in the cell nuclei were obtained using confocal microscopy of fluorescent Feulgen-stained preparations. The distribution of the rDNA 18S sites was determined using confocal microscopy of preparations subjected to a FISH assay in which species-specific probes were employed. The chromocenters in both species were found to be positioned with relative proximity to the nuclear periphery, although not adjacent to it. Because the distance between the chromocenters and the nuclear periphery varies, it is suggested that such a spatial distribution follows a dynamic organization that permits chromocenter motions inside the cell nuclei. This distance enlarges with the nymphal development probably due to the increasing polyploidization that affects the insect nuclei and that consequently leads them to increased values of euchromatin volumes. Although the here-studied chromocenters acquire a non-casual position inside the cell nuclei and their distribution suggests that they are passive of dynamic motions, no relationship was detected between their topology and the distribution of their rDNA 18S sites. Because rDNA 18S sites could also be revealed in chromocenter regions facing the nuclear periphery, the proximity of the chromocenters to this nuclear region is not assumed to be associated with gene silencing or low gene densityMestradoBiologia CelularMestre em Biologia Celular e Estrutural2015/10356-2  CAPESFAPES

Resveratrol and Curcumin for Chagas Disease Treatment—A Systematic Review

Chagas disease (CD) is a neglected protozoan infection caused by Trypanosoma cruzi, which affects about 7 million people worldwide. There are two available drugs in therapeutics, however, they lack effectiveness for the chronic stage—characterized mainly by cardiac (i.e., cardiomyopathy) and digestive manifestations (i.e., megaesophagus, megacolon). Due to the involvement of the immuno-inflammatory pathways in the disease’s progress, compounds exhibiting antioxidant and anti-inflammatory activity seem to be effective for controlling some clinical manifestations, mainly in the chronic phase. Resveratrol (RVT) and curcumin (CUR) are natural compounds with potent antioxidant and anti-inflammatory properties and their cardioprotective effect have been proposed to have benefits to treat CD. Such effects could decrease or block the progression of the disease’s severity. The purpose of this systematic review is to analyze the effectiveness of RVT and CUR in animal and clinical research for the treatment of CD. The study was performed according to PRISMA guidelines and it was registered on PROSPERO (CDR42021293495). The results did not find any clinical study, and the animal research was analyzed according to the SYRCLES risk of bias tools and ARRIVE 2.0 guidelines. We found 9 eligible reports in this study. We also discuss the potential RVT and CUR derivatives for the treatment of CD as well