Maria Carolina Viana

Electronic Nicotine Delivery Devices (ENDS), commonly known as e-cigarettes, have become increasingly popular. However, despite the well-established human health risks, the mechanisms of carcinogenesis remain unclear. The key characteristics of carcinogens provide an efficient strategy for identifying and organizing data from mechanistic studies. We aimed to identify, organize, and synthesize the biological evidence indicating the carcinogenic potential of these devices, categorizing them into five key characteristics potentially involved in cancer initiation and/or promotion: immunosuppression, inflammation, genotoxicity, oxidative stress, and epigenetic alterations. A narrative review was conducted through a bibliographic search of articles published in English over the past ten years (2015-2025) in the following scientific databases PubMed, Scopus, EMBASE, and Lilacs, using an extensive combination of exposure and effect descriptors. The analysis of the selected studies suggests that e-cigarettes cause toxic effects on the immune system (immunosuppressive and pro-inflammatory activity), on DNA (genotoxicity and oxidative stress effects), and act as a disruptor of gene expression.

Resumo Dispositivos eletrônicos de administração de nicotina (ENDS, na sigla em inglês), comumente conhecidos como cigarros eletrônicos, tornaram-se cada vez mais populares. No entanto, apesar dos riscos bem estabelecidos para a saúde humana, os mecanismos de carcinogênese permanecem obscuros. As principais características dos carcinógenos fornecem uma estratégia eficiente para identificar e organizar dados de estudos mecanísticos. Nosso objetivo foi identificar, organizar e sintetizar as evidências biológicas que indicam o potencial carcinogênico desses dispositivos, categorizando-as em cinco características principais potencialmente envolvidas na iniciação e/ou promoção do câncer: imunossupressão, inflamação, genotoxicidade, estresse oxidativo e alterações epigenéticas. Uma revisão narrativa foi conduzida por meio de uma busca bibliográfica de artigos publicados em inglês nos últimos dez anos (2015-2025) nas bases de dados científicas PubMed, Scopus, EMBASE e Lilacs, utilizando uma ampla combinação de descritores de exposição e efeito. A análise dos estudos selecionados sugere que os cigarros eletrônicos causam efeitos tóxicos no sistema imunológico (atividade imunossupressora e pró-inflamatória), no DNA (efeitos de genotoxicidade e estresse oxidativo) e atuam como disruptores da expressão gênica.

Two species of manatees are found in Northern Brazil—the Antillean manatee (Trichechus manatus), which is found along the coast from Florida to Northeastern Brazil, and the Amazonian manatee (Trichechus inunguis), endemic to the Amazon drainage basin. These species show a sympatric distribution in the region of the Marajó Archipelago, an estuarine area surrounding the Amazon River mouth. There is evidence of the occurrence of interspecific hybrids in this area, based on mitochondrial DNA analyses, although the use of nuclear markers has not corroborated this proposal. Considering that these species show very distinct karyotypes, despite being closely related (2n = 48 in T. manatus and 2n = 56 in T. inunguis), hybrids would present distinct chromosome numbers. Based on this, we conducted cytogenetic analyses using classic and molecular techniques in three calves found stranded in the Marajó Island and Amapá coast. The results showed that one of them, morphologically classified as T. inunguis, presented the correspondent karyotype, with 2n = 56. However, the other two, which were phenotypically similar to T. manatus, showed 2n = 49. Despite the same diploid number, their G-banding patterns revealed some differences. The results of the distribution of some microsatellite sequences have also confirmed the heterozygosity of some chromosomal pairs in these two individuals. These results are the first indubitable confirmation of the occurrence of natural hybrids between T. manatus and T. inunguis, and also brings about some issues concerning the viability of hybrids, considering that these two individuals do not correspond to an F1 hybrid, but instead, both presented a possible F2 karyotype.

South America is unique as it is home of two species of manatees: the West Indian manatee, Trichechus manatus, and the Amazonian manatee, T. inunguis. These species are easily identified by the belly skin coloration, the first is entirely gray whereas T. inunguis has a white mark pattern in the belly, and presence of nails in T. manatus, absent in T. inunguis. The morphology and the range of Trichechus species have been clearly established. However, we show that the belly skin coloration and the presence of nails on the pectoral flipper may be polymorphic. These findings prompted us to check all available information about the manatee. In view of lack of accurate data on manatee locations, we produced a gazetteer and a map of Trichechus spp. in South America using records obtained by regular monitoring of aquatic mammal strandings conducted by the Grupo de Estudos de Mamíferos Aquáticos da Amazônia of the Museu Paraense Emílio Goeldi, all available peer-reviewed data, reports, thesis, and newspaper files with photos showing diagnostic characters. These findings showed the need of improving the identification of these species before implementing conservation strategies. Finally, we present a complete report on the extant distribution of these species in South America.

Background: The protozoan Trypanosoma cruzi circulates in semiarid areas of northeastern Brazil in distinct ecotopes (sylvatic, peridomestic and domestic) where Triatoma brasiliensis Neiva, 1911 is the most important Chagas disease vector. In this study, we analyzed microevolutionary and demographic aspects of T. brasiliensis populations at the ecotypic, micro and macro-geographic scales by combining morphometrics and molecular results. Additionally, we aimed to address the resolution of both markers for delimiting populations in distinct scales. Methods: We sampled populations of T. brasiliensis from distinct ecotypic and geographic sites in the states Rio Grande do Norte (RN) and Paraíba (PB). The geometric morphometry was carried out with 13 landmarks on the right wings (n = 698) and the genetic structure was assessed by sequencing a region of cytochrome b mitochondrial gene (n = 221). Mahalanobis distance (MD) and coefficient of molecular differentiation (Φ_ST) were calculated among all pairs of populations. The results of comparisons generated MD and Φ_ST dendrograms, and graphics of canonical variate analysis (CVA). Results: Little structure was observed for both markers for macro-geographic scales. Mantel tests comparing geographic, morphometric and genetic matrices showed low correlation (all R² < 0.35). The factorial graphics built with the CVA evidenced population delimitation for the morphometric data at micro-geographic scales. Conclusions: We believe that T. brasiliensis carries in its genotype a source of information to allow the phenotypical plasticity across its whole distribution for shaping populations, which may have caused a lack of population delimitation for CVAs in morphometric analysis for macro-geographic scale analysis. On the other hand, the pattern of morphometric results in micro-geographic scales showed well-defined groups, highlighting the potential of this tool to inferences on the source for infestation.

Traditionally, the morphological attributes and the range of Trichechus species have been clearly established. However, we herein show that morphological traits, like belly and pectoral flipper coloration in South American manatees may be polymorphic. Karyotypic analysis of T. manatus allowed the precise identification of this species and confirmed the variability of the observed morphological findings. Molecular analysis based on cytochrome b DNA and the D-loop mitochondrial region showed shared haplotypes between T. inunguis and T. manatus, suggesting the presence of an ancestral polymorphism. These findings showed the need of improving the identification of these species before implementing conservation strategies. Finally, we present a complete report on the extant distribution of these species in South America.