Universidade Federal Do Para

The Cosmetocleithrum represents the most diverse group of monogenoids parasitizing Neotropical doradid catfishes. In this study, based on morphological and molecular data, we describe two new species, Cosmetocleithrum guamaensis n. sp. and Cosmetocleithrum taeniophallum n. sp., and assess their phylogenetic relationships within the Dactylogyridae using partial 28S rDNA sequences. Our analyses support the validity of these new taxa and suggest their phylogenetic affinity with Cosmetocleithrum species parasitizing auchenipterid catfishes. Additionally, we confirm the presence of Cosmetocleithrum falsunilatum and Cosmetocleithrum bulbocirrus in Megalodoras uranoscopus and Pterodoras granulosus, respectively, with C. falsunilatum exhibiting notable morphological variation across river basins, possibly influenced by environmental factors. Our phylogenetic results corroborate previous studies indicating two distinct Cosmetocleithrum lineages, one exclusively associated with doradids and another with both doradids and auchenipterids, with weak support for the genus' monophyly. Furthermore, we discuss morphological diversity within Cosmetocleithrum, highlighting significant variation in key diagnostic features, including haptoral structures, copulatory complex morphology, and vaginal opening orientation. These findings reinforce previous hypotheses suggesting that Cosmetocleithrum may not constitute a natural group and that taxonomic revisions are needed. The limited molecular data available for Cosmetocleithrum species (with only 13 out of 31 described species studied) and the disparity between the number of known doradid hosts and those surveyed for monogenoids highlight the urgent need for further integrative taxonomic and phylogenetic studies. This approach will be crucial for providing valuable insights and advancing our understanding of the complex evolutionary puzzle of one of the largest genera of monogenoids parasitizing Neotropical Siluriformes.

Understanding how metal-organic complexes behave under extreme conditions is crucial for designing advanced materials. Here, we present a comprehensive investigation of the [Cu(Bip)₂(Cl)]⁺ complex. Its structural properties were characterized by powder X-ray diffraction with Rietveld refinement. Additionally, the study incorporated High-pressure Raman spectroscopy (up to 7.5 GPa), which was complemented by density functional theory (DFT) calculations for accurate vibrational mode assignment, alongside Hirshfeld surface analysis. Our results reveal a gradual conformational phase transition in the [Cu(Bip)₂(Cl)]⁺ complex occurring between 1.0 and 4.0 GPa. This transition is primarily driven by changes in intermolecular interactions, including the emergence of a new CH stretching mode and subtle variations in the CuCl stretching mode. Notably, the molecular framework of the complex remains remarkably rigid, with only minimal pressure-induced shifts observed in its internal vibrational modes up to 7.5 GPa. This contrasts with pure pyridine, which undergoes significant structural changes under pressure. The enhanced rigidity of [Cu(Bip)₂(Cl)]⁺ stems from the distinct nature of its intermolecular forces: while hydrogen bonds in pyridine contribute to great mechanical strength, the van der Waals forces in [Cu(Bip)₂(Cl)]⁺ promote compressibility, enabling a progressive conformational transition rather than abrupt structural collapse. The structural reversibility and stability of the complex under pressure highlight its potential for applications in variable-pressure environments, such as sensors and optoelectronic devices.

Stress occurs as a reaction to mental and emotional pressure, anxiety, or scarring. Chronic stress is defined as constant submission to these moments. It can affect several body systems, increase blood pressure, and weaken immunity, thereby interfering with physiological health processes. Thus, this study aims to evaluate the effects of chronic stress on the redox status and histomorphological parameters of salivary glands. Thirty-two albino Wistar male rats were randomly divided into two groups: chronic stress and control. Chronically stressed animals were subjected to a restraint protocol by introducing them into a polyvinyl tube for 4 hours daily for 28 days, allowing immobilization of their movements. Subsequently, the animals were euthanized for further collection of the parotid and submandibular salivary glands. The redox state of the glands was evaluated using the antioxidant capacity against peroxyl radicals (ACAP) and thiobarbituric acid reactive substances (TBARS) assays. Histological analysis was performed through morphometry of the tissues stained with hematoxylin and eosin and histochemical through picrosirius red staining. Both the parotid and submandibular glands of stressed rats exhibited oxidative stress due to a decrease in ACAP and an increase in TBARS levels. However, the parotid glands are more susceptible to harmful changes in the tissue, such as an increase in the stromal area and in the collagen area fraction, decrease in the acinar area, and smaller size of the acinus and ducts. Our results suggest that chronic stress may cause harmful modulation of the redox state of the salivary glands, with different histological repercussions.