Biology subjects

Ferreira, G. S.

Publications and source records attributed to Ferreira, G. S..

3 recordsLinked to original sources

bioRxiv2026

HUMAN-LIKE SIALOME REMODELING LINKS HYPERGLYCEMIA TO COLORECTAL CANCER PROGRESSION

The evolutionary loss of cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH) abolished endogenous N-glycolylneuraminic acid (Neu5Gc) synthesis in humans, reshaping the sialic acid at the cell surface glycans and influencing immune and metabolic processes. However, whether a human-like sialome modulates the impact of metabolic stress on colorectal cancer (CRC) progression remains unclear. Here, we investigated the diabetes-sialome-tumor axis using a spontaneous CRC model combining conditional Apc mutation with Cmah deficiency, thereby recapitulating the human sialic acid repertoire. Under euglycemic conditions, CPC-Apc Cmah-/- mice exhibited reduced polyp numbers and tumor burden compared with WT mice, accompanied by remodeling of the tumor immune microenvironment, including increased tumor-infiltrating leukocytes, enrichment of B cells, and reduced PD-1 expression in B cells and cytotoxic CD8+ T cells. Induction of chronic hyperglycemia with low-dose streptozotocin revealed a striking genotype-specific effect. Despite comparable hyperglycemia between genotypes, tumor progression was dramatically exacerbated exclusively in Cmah-/- mice, with increased tumor burden, accelerated lesion development, and progression toward high-grade dysplasia. Histopathological analyses further revealed increased mesenchymal expansion and close resemblance to colorectal tumors from diabetic patients. Together, these findings demonstrate that a human-like sialome increases susceptibility to metabolic stress and identify CPC-Apc Cmah-/- mice as a translationally relevant model for investigating diabetes-associated colorectal carcinogenesis.

cancer biology↗

bioRxiv2022

Turtle body size evolution is determined by lineage-specific specializations rather than global trends

Organisms display considerable variety of body sizes and shapes, and macroevolutionary investigations help to understand the evolutionary dynamics behind to such variations. Turtles (Testudinata) show great body size disparity, especially when their rich fossil record is accounted for. We explored body size evolution in turtles, testing which factors might influence the observed patterns and evaluating the existence of long-term directional trends. We constructed the most comprehensive body size dataset for the group to date, tested for correlation with paleotemperature, estimated ancestral body sizes, and performed macroevolutionary model-fitting analyses. We found no evidence for directional body size evolution, even when using very flexible models, thereby rejecting the occurrence of Copes rule. We also found no significant effect of paleotemperature on overall through-time body size patterns. In contrast, we found a significant influence of habitat preference on turtle body size. Freshwater turtles display a rather homogenous body size distribution through time. In contrast, terrestrial and marine turtles show more pronounced variation, with terrestrial forms being restricted to larger body sizes, up to the origin of testudinids in the Cenozoic, and marine turtles undergoing a reduction in body size disparity after the extinctions of many groups in the mid-Cenozoic. Our results therefore suggest that long-term, generalized patterns are probably explained by factors specific to certain groups and related at least partly to habitat use.

evolutionary biology↗

bioRxiv2019

A unique predator in a unique ecosystem: modelling the apex predator from the Late Cretaceous crocodyliform-dominated fauna in Brazil.

ABSTRACTTheropod dinosaurs were relatively scarce in the Late Cretaceous ecosystems of southeast Brazil. Instead, hypercarnivorous crocodyliforms known as baurusuchids were abundant and probably occupied the ecological role of apex predators. Baurusuchids exhibited a series of morphological adaptations hypothesised to be associated with this ecological role, but quantitative biomechanical analyses of their morphology have so far been lacking. Here, we employ a biomechanical modelling approach, applying finite element analysis (FEA) to models of the skull and mandibles of a baurusuchid specimen. This allowed us to characterise the craniomandibular apparatus of baurusuchids, as well as to compare the functional morphology of the group to that of other archosaurian carnivores, such as theropods and crocodylians. Our results support the ecological role of baurusuchids as specialised apex predators in the continental Late Cretaceous ecosystems of South America. With a relatively weak bite force (∼600 N), baurusuchids’ predation strategies likely relied on other morphological specializations, such as ziphodont dentition and strong cervical musculature. Comparative assessments of the stress distribution and magnitude of scaled models of other predators (the theropod Allosaurus fragilis and the living crocodylian Alligator mississippiensis) consistently show different responses to loadings under the same functional scenarios, suggesting distinct predatory behaviours for these animals. The unique selective pressures in the arid to semi-arid Late Cretaceous ecosystems of southeast Brazil, which were dominated by crocodyliforms, possibly drove the emergence and evolution of the biomechanical features seen in baurusuchids, which are distinct from those previously reported for other predatory taxa.View Full Text

paleontology↗