Cachexia (CC) is a complex wasting syndrome that significantly affects life quality and life expectancy among cancer patients. Original studies, in which CC was induced in mouse models through inoculation with BaF and C26 tumour cells, demonstrated that CC development correlates with bacterial gut dysbiosis in these animals. In both cases, a common microbial signature was observed, based on the expansion of Enterobacteriaceae in the gut of CC animals. However, these two types of tumours induce unique microbial profiles, suggesting that different CC induction mechanisms significantly impact the outcome of gut dysbiosis. The present study sought to expand the scope of such analyses by characterizing the CC-associated dysbiosis that develops when mice are inoculated with Lewis lung carcinoma (LLC) cells, which constitutes one of the most widely employed mechanisms for CC induction. Interestingly, Enterobacteriaceae expansion is also observed in LLC-induced CC. However, the dysbiosis identified herein displays a more complex pattern, involving representatives from seven different bacterial phyla, which were consistently identified across successive levels of taxonomic hierarchy. These results are supported by a predictive analysis of gene content, which identified a series of functional/structural changes that potentially occur in the gut bacterial population of these animals, providing a complementary and alternative approach to microbiome analyses based solely on taxonomic classification.

Background/Objectives: Variation in repeatome composition is a major determinant of genome architecture and an important substrate for evolutionary change in plants. Despite the availability of genomic sequence data, repeatome-wide assessments have not been performed for Epidendrum, the largest Neotropical genus of Orchidaceae. Here, we assessed repeatome profiles across 34 Epidendrum species using publicly available genomic datasets. Methods:Epidendrum repeatomes were characterized with the RepeatExplorer2 pipeline, and patterns of repeat composition were evaluated for phylogenetic structure using a species phylogeny. Results: Repeat composition showed no clear phylogenetic structure, with closely related species often displaying divergent satDNA and TE profiles. satDNA content varied widely among species (15.5–69% of the repeatome fraction). A total of 208 satDNA families were detected, which were used to build a custom database for comparative analyses. We detected 73 satDNA clusters shared among species, whereas only three were species-specific. Regarding TEs, Class I elements were the most abundant repeats, dominated by Ty3-Gypsy LTR retrotransposons. Only two Class II TIR superfamilies were detected (EnSpm/CACTA and hAT). Conclusions: This study provides the first comprehensive characterization of the Epidendrum repeatome and establishes a resource for future work on cytogenomic diversity within this megagenus. The heterogeneous distribution of repeats among closely related species is consistent with lineage-specific amplification and loss, highlighting rapid repeatome turnover in Epidendrum. Potential drivers, as hybridization and ecological differentiation, should be tested explicitly in future analyses integrating broader genome size sampling and trait data.

The repeatome is composed of satellite DNA (satDNA) and transposable elements (TEs), and variation in its composition is important for shaping genome architecture and driving evolutionary processes in plants. As no repeatome assessment exists for Epidendrum, the largest genus of Orchidaceae in the Neotropics, we aim to describe repetitive sequences across its species. We performed phylogenetic analyses based on plastid (matK and rbcL) and nuclear (ITS) markers using maximum likelihood and Bayesian inference methods, and characterized the repeatome of 34 species using the RepeatExplorer2 pipeline. Our results reveal substantial variation in satDNA content among species, with a total of 208 individually identified satDNAs, which were used to build a custom database for repeatome comparative analysis. We found that 73 satDNA clusters are shared among species, while only three are species-specific (CL359 and CL82 in E. rigidum, and CL430 in E. gasteriferum), supporting the library hypothesis. Regarding TEs, Class I elements were the most abundant repeats identified in Epidendrum, primarily long terminal repeat retrotransposons of the Ty3-gypsy superfamily. Elements of the Ty1-copia superfamily were the least abundant. Only two Class II TIR superfamilies were identified, namely EnSpm_CACTA and hAT. The heterogeneous distribution of satDNAs and TEs among closely related species suggests lineage-specific patterns of expansion and contraction, potentially influenced by evolutionary processes such as hybridization and environmental adaptation. Our findings represent the first comprehensive characterization of the repeatome in Epidendrum and provide a basis for future studies on the composition and cytogenomic variation within the mega-genus.