Morphological description of the alimentary canal and adnexal glands in Amazilia tzacatl, Amazilia saucerottei, Amazilia amabilis and Anthrachotorax nigricollis species.

The hummingbird family (Trochilidae) includes the smallest and most metabolically active vertebrates. They have a high energy demand because of their extraordinarily high metabolic rates during hovering while looking for food. The morphology of the digestive apparatus is related to the feeding habits of the species. The anatomy and histology of the digestive apparatus in these birds have not been thoroughly described except for their tongue. Therefore, this study aimed to describe the gross anatomy and histology of the alimentary canal and adnexal glands in four species from the hummingbird family: Amazilia tzacatl (n = 2), Amazilia saucerottei (n = 1), Amazilia amabilis (n = 1) and Anthracothorax nigricollis (n = 1). The alimentary canal was found to be very short. The epithelium of the oesophagus and crop showed variable degrees of keratinization and parakeratotic areas as normal conditions. A dorsal crop was observed as a differential characteristic of these birds. Like other birds, the ventricular mucosa in hummingbirds was covered and protected by the cuticle and showed a tunica muscularis constituted by three muscle layers. There was no isthmus between the proventriculus and ventriculus. The intestine presents a well-differentiated duodenum and jejunum. However, no ileum nor caeca were identified. The intestinal villi length, base width, crypt depth and area showed differences among the specimens studied among the small and large intestines. In addition, variations in thickness were observed in the smooth muscle tunica along the intestine. In all the studied species, the liver was composed of two lobes (right and left), and no gall bladder was observed during gross inspection or in histological sections. Finally, the pancreas was observed as a diffused organ forming islets related to all the small intestines. Some anatomical differences were observed among the studied species, mainly concerning Anthracothorax nigricollis. Hummingbirds showed very interesting and distinctive morphological characteristics. Hummingbirds possess unique and intriguing morphological characteristics. Future comparative studies related to the anatomy, histology and function of the digestive apparatus of hummingbirds are required. Expanding our understanding of the digestive morphophysiology in these bird species is crucial. However, it is necessary to conduct more comprehensive studies encompassing a wider range of hummingbird species and including a larger number of individuals to obtain more conclusive findings.

The Role of Sirtuins in Cell Life and their Potential Therapeutic Uses.

Sirtuins (SIRTs) constitute a family of enzyme-type proteins dependent on nicotinamide adenine dinucleotide. These enzymes are considered cellular metabolic sensors since the cell's energy level can regulate their activity to compensate for energy fluctuations. They constitute an evolutionarily conserved family of deacetylases class III enzymes, with a recognized role in prolonging life expectancy. Sirtuins are related to the development of age-associated pathologies, such as cancer, diabetes, neurodegeneration, and metabolic disorders. This group of enzymes has become a possible therapeutic target due to their capacity for modulating cellular processes, such as genome repair and maintenance, and for regulating metabolic pathways, homeostasis, and cell proliferation. In addition, SIRTs are associated with pathologies such as cancer and COVID-19. There is a need for future studies that will clarify the relationship between these enzymes group and the prevention and development of diseases.

Distinct ß-glucan molecules modulates differently the circulating cortisol levels and innate immune responses in matrinxã (Brycon amazonicus).

This study investigated the effects of two ß-glucan molecules with different purities and isolated by different biotechnological processes on the immune response of matrinxã (Brycon amazonicus) prior and after challenge with Aeromonas hydrophila. In this sense, we evaluated serum cortisol and plasma glucose levels, the number of leukocytes (lymphocytes, neutrophils and monocytes), as well as the respiratory activity of leukocytes prior to, 6 and 24 h post infection (hpi). During 15 days, fish were fed with diets containing 0.1% of two ß-glucans (ß-G 1 and ß-G 2, with 71 and 62% of purity, respectively) and then submitted to challenge. Results were compared with a positive control group fed with a ß-glucan-free diet. A negative control group, also fed with ß-glucan-free diet but inoculated with PBS, was established to evaluate the effect of handling during injection. Our results showed that different ß-glucans affected differently the biological responses of matrinxã. The ßG 2 modulated the cortisol profile prior to and after the acute infection with A. hydrophila, and increased the mobilization and activity of leukocytes. The infection promoted lymphopenia at 6 hpi and both ß-glucans increased the circulating lymphocyte population 24 hpi. Moreover, the ß-G 2 prevented the infection-induced neutrophilia at 6 and 24 hpi. Finally, the ß-G 2 caused a marked increase in the circulating monocytes prior to infection, and a reduction at 6 hpi that was reversed at 24 hpi. In summary, our study demonstrates that ß-G 2 was more efficient on the induction of the cell-mediate immunity in matrinxã.