Analia Verónica Fernández-Gimenez

The cannonball jellyfish Stomolophus sp.2 is distributed in the southern region of the Gulf of California. At high temperatures, it shows metabolic responses that produce large amounts of adenosine triphosphate (ATP) to cope with thermal stress. In addition to mitochondria, phosphagens are suggested as one mechanism for rapid ATP production in this species. Recently, two transcripts encoding the phosphagen-kinase homologs, arginine kinase (AK) and creatine kinase (CK), were confirmed in the jellyfish transcriptome as part of the species' ability to synthesize ATP. This study identifies and characterizes both enzymes to understand the molecular adaptations of Stomolophus sp.2 to environmental challenges, and explores the evolution of this family of enzymes in the animal kingdom. The transcripts and deduced proteins from jellyfish AK and CK were analyzed and confirmed through bioinformatic analysis. Conserved domains in both proteins and their predicted structures confirmed their identity. Phylogenetic trees were built to explore these proteins' evolutionary origin in early animal history. Results revealed that the AK and CK sequences of jellyfish share conserved phosphagen-kinase signatures, N- and C-terminal domains, and a specific active site. Phylogeny suggests a divergence event in later clades, emphasizing the conservation and evolution of these enzymes. This study provides new evidence on the presence of the two phosphagen enzymes in the jellyfish; these findings expand our understanding of the evolution and molecular adaptation of phosphagen enzymes in the animal kingdom, highlighting the biological plasticity of Stomolophus sp.2 to face climate change.

Due to the scarcity of data cited in the literature, digestive enzyme profiles of fish species from the southwestern Atlantic Ocean are of particular interest. In the present study, the viscera yield and digestive enzymes (acid and alkaline proteinase, lipase and amylase) of the stripped weakfish Cynoscion guatucupa, Brazilian codling Urophycis brasiliensis, Patagonian flounder Paralichthys patagonicus, southern eagle ray Myliobatis goodei and smallnose fanskate Sympterygia bonapartii were determined. All species exhibited high proteolytic activity (acid: 0.44-11.0 UE mg protein-1 and alkaline: 0.11-2.32 UE mg protein-1) as well as moderate lipase (0.07-0.76 UE mg protein-1) and amylase activity (0.03-0.24 UE mg protein-1). Teleost fish exhibited higher enzyme activities than cartilaginous fish, with U. brasiliensis exhibiting the highest activities (proteinases, amylases, and lipases). High-activity enzymes from cold-temperate-adapted organisms, mainly from U. brasiliensis and C. guatucupa, may be the source of marine biotechnological bioactive compounds that are beneficial for biotechnological processes.

Fish visceral waste, which is normally discarded, is considered one of the richest sources of proteinases with potential biotechnological applications. For this reason, alkaline proteinases from viscera of Argentine hake Merluccius hubbsi, Brazilian flathead Percophis brasiliensis, Brazilian codling Urophycis brasiliensis, and stripped weakfish Cynoscion guatucupa were characterized. Individuals were caught by a commercial fleet off the coast of the Argentinean Sea. The intestine and pyloric caeca were dissected out and then minced and triturated with distilled water. The proteinase activity of P. brasiliensis extracts was enhanced by all the ions tested (Mn²⁺, K⁺, Na⁺, Ca⁺²) while the enzymes of the other species were stable in the presence of those ions, retaining more than 60% of their enzymatic activity. Alkaline proteinases of all species showed extreme stability to 5% v/v surfactants at 60 min (Sodium dodecyl sulfate, Triton X‐100, Tween 20, Tween 80), and relative stability toward an 6% v/v oxidizing agent (H₂O₂) and organic solvents 80% (acetone, isopropanol, methanol, ethanol). The enzyme extracts were incubated for 60 min with these compounds. Interestingly, alkaline proteinases from all species were compatible with the commercial detergents (Ala, Skip, and Ace). These results demonstrate that proteinases recovered from a no‐cost sample such as fishery residues can be used for industrial applications, such as detergent formulations.

Marine biofouling is a global issue with economic and ecological implications. Existing solutions, such as biocide-based antifouling paints, are toxic for the environment. The search for better antifouling agents remains crucial. Recent research focuses on eco-friendly antifouling paints containing natural compounds like enzymes. This study evaluates enzymatic extracts from fishery residues for antifouling potential. Extracts from Pleoticus muelleri shrimp, Illex argentinus squid, and Lithodes santolla king crab were analyzed. Proteolytic activity and thermal stability were assessed, followed by bioassays on mussel byssus thread formation and barnacle cypris adhesive footprints. All three extracts demonstrated proteolytic activity and 24-h stability at temperate oceanic temperatures, except I. argentinus. P. muelleri extracts hindered cyprid footprint formation and mussel byssus thread generation. Further purification is required for L. santolla extract to assess its antifouling potential activity. This study introduces the use of fishery waste-derived enzyme extracts as a novel antifouling agent, providing a sustainable tool to fight against biofouling formation.

Understanding the nutritional and metabolic physiology of aquatic organisms is essential for optimizing aquaculture practices and informing ecological models. We investigated the influence of dietary composition, specifically the incorporation of multienzyme extract derived from Pleoticus muelleri waste, on the growth and metabolic processes of juvenile Cherax quadricarinatus. We investigated how these dietary changes influence dietary assimilation and tissue turnover using stable isotope δ¹³C and δ¹⁵N dynamics, in both the pleon muscle and hepatopancreas. Juvenile crayfish were subjected to two isocaloric diets for a 90‐day period: a control diet (diet C) and a diet supplemented with a multienzyme extract (diet E) from red shrimp waste. Despite comparable growth rates, isotopic analysis (δ¹³C and δ¹⁵N) of the pleon muscle and hepatopancreas revealed distinct metabolic patterns between both dietary treatments. The hepatopancreas exhibited accelerated isotopic turnover relative to muscle tissue, irrespective of diet, suggesting a more dynamic metabolic role. Diet E further accelerated turnover rates in both tissues, indicative of enhanced nutrient assimilation and utilization. Consistent isotopic disparities between the hepatopancreas and muscle tissues highlighted tissue‐specific metabolic functions, with the hepatopancreas serving as a metabolic hub. Molting‐induced shifts in isotopic patterns underscored the dynamic interplay between metabolic processes and nutrient mobilization. Isotopic equilibrium was reached earlier for δ¹³C than δ¹⁵N, with lower discrimination factors in the hepatopancreas. While δ¹³C primarily supported metabolic processes, δ¹⁵N contributed substantially to growth, especially in muscle. These findings illuminate the complex interplay of dietary composition, isotopic fractionation, and physiological regulation in C. quadricarinatus. The metabolic enhancements induced by the diet supplemented with the extract warrant further investigation to optimize nutrient utilization and growth performance in aquaculture settings.