Patterns of energetic substrate modifications in response to feeding in boas, Boa constrictor (Serpentes, Boidae).

Ambush-foraging snakes that ingest large meals might undergo several months without eating when they use the internal reserves to support the energetic costs of living. Then, morphological and physiological processes might be orchestrated during the transition from fasting to the postprandial period to rapidly use the energetic stores while the metabolic rate is elevated in response to food intake. To understand the patterns of substrates deposition after feeding, we accessed the morphological and biochemical response in Boa constrictor snakes after two months of fasting and six days after feeding. We followed the plasma levels of glucose, total proteins, and total lipids, and we performed the stereological ultrastructural analysis of the liver and the proximal region of the intestine to quantify glycogen granules and lipid droplets. In the same tissues and stomach, we measured the activity of the enzyme fructose-1,6-biphosphatase (FBPase1) involved in the gluconeogenic pathway, and we measured pyruvate kinase (PK) and lactate dehydrogenase (LDH) enzymatic activities involved in the anaerobic pathway in the liver. Briefly, our results indicated an increase in boas' plasma glucose one day after meal intake compared to unfed snakes. The hepatic glycogen reserves were continuously restored within days after feeding. Also, the enzymes involved in the energetic pathways increased activity six days after feeding in the liver. These findings suggest a quick restoring pattern of energetic stores during the postprandial period.

Feeding effects on liver mitochondrial bioenergetics of Boa constrictor (Serpentes: Boidae).

Snakes are interesting examples of taxa that can overcome energy metabolism challenges, as many species can endure long periods without feeding, and their eventual meals are of reasonably large sizes, thus exhibiting dual extreme adaptations. Consequently, metabolic rate increases considerably to attend to the energetic demand of digestion, absorption and protein synthesis. These animals should be adapted to transition from these two opposite states of energy fairly quickly, and therefore we investigated mitochondrial function plasticity in these states. Herein, we compared liver mitochondrial bioenergetics of the boid snake Boa constrictor during fasting and after meal intake. We fasted the snakes for 60 days, and then we fed a subgroup with 30% of their body size and evaluated their maximum postprandial response. We measured liver respiration rates from permeabilized tissue and isolated mitochondria. From isolated mitochondria, we also measured Ca2+ retention capacity and redox status. Mitochondrial respiration rates were maximized after feeding, reaching an approximately 60% increase from fasting levels when energized with complex I-linked substrates. Interestingly, fasting and fed snakes exhibited similar respiratory control ratios and citrate synthase activity. Furthermore, we found no differences in Ca2+ retention capacity, indicating no increase in susceptibility to mitochondrial permeability transition, and no changes in mitochondrial redox state, although fed animals exhibited increases in the release of H2O2. Thus, we conclude that liver mitochondria from B. constrictor snakes increase respiration rates during the postprandial period and quickly improve the bioenergetic capacity without compromising redox balance.

Gill Morphology and Na+/K+-ATPase Activity of Gobionellus oceanicus (Teleostei: Gobiidae) in an Estuarine System.

Gobionellus oceanicus is a species widely distributed on the Atlantic coast and may be susceptible to anthropic effects. This study evaluated the morphology and the Na+/K+-ATPase activity of G. oceanicus gills considering the concentration of metals in the fish and Subaé River estuary. Although the metal concentrations detected in the water and sediment did not exceed certain limits, CONAMA (Brazilian Environment Council), TEL (Threshold Effect Level), and PEL (Probable Effect Level), the metals levels in gills plus muscle and skin of G. oceanicus were above the permitted setting of the Ministry of Health, Brazil. The pavement epithelial cells (PVC) of the gill filament was observed that there were long microridges either in the apical surface or in the lamella; especially, microridges degeneration was shown in some PVC from filament epithelium. The number of ionocyte and the volume density were (0.02 ± 0.001)/µm and (0.38 ± 0.27) %, respectively. The activity of Na+/K+-ATPase was 1.13 ± 0.76 µM Pi mg protein-1 h-1. We describe the volume density and number of ionocytes and Na+/K+-ATPase enzymatic activity in G. oceanicus for the first time, which is useful for basic and comparative future studies to support aquatic biomonitoring.