The growing global demand for fish necessitates the exploration of sustainable aquaculture practices. This has led to a focus on the quality and sustainable production of fish products with minimal environmental impact. Thus, the objective of this review is to study and evaluate how different aquaculture systems impact the quality and nutritional profile of fish. Fish are rich sources of protein, containing almost 20% protein and essential amino acids and vitamins. The nutritional value and quality of fish products are directly related to the conditions under which they are produced through aquaculture. This article considers various aquaculture systems, including closed-loop systems, pond farming, marine aquaculture, and aquaponic systems. The operating principles, advantages, and inherent limitations of each fish-rearing system are subjected to rigorous critical analysis in this review. Such practices are necessary to meet the growing demand for fish and to maintain the integrity of aquatic ecosystems for future generations.

The foliar feeding of soil-grown plants with essential elements such as molybdate can restore their Nitrate reductase activity. However, the activity of nitrate reductase under the foliar feeding of plants with molybdate and nitrate in hydroponic conditions has not been investigated. Thus, we wanted to investigate the effect of the foliar feeding of molybdate and nitrate on the nitrate reductase activity in the leaves of lemon balm plants under hydroponic conditions. Nitrate and molybdate solutions were applied by spraying the leaves of lemon balm plants and the nitrate reductase activity was determined by the colorimetric method. The results of our study demonstrated that the application of molybdate and KNO₃ solution enhanced the nitrate reductase activity in the leaves of lemon balm plants. Importantly, our results indicate that foliar fertilization with nitrate and molybdate can improve nitrogen metabolism and carbon fixation in the leaves of lemon balm plants under hydroponic conditions.

Nitric oxide (NO) plays numerous essential physiological functions in?terrestrial animals. In?mammals, NO production from l-arginine is catalysed by?the enzyme NO synthase (NOS). In?recent years, data have begun to?emerge on NOS expression and...

Molybdenum enzymes (Mo-enzymes) contain a molybdenum cofactor (MoCo) in the active site. These enzymes are potentially interesting for studying the survival mechanism of fish under hypoxic water conditions. This is because Mo-enzymes can synthesize nitric oxide from nitrates and nitrites, which are present in high concentrations under hypoxic water conditions. However, there is currently no method for assessing the Mo-enzymes content in the fish internal organs. Methods capable of determining Mo-enzymes content in the fish are of major importance. For this purpose, a method for quantitative determination of MoCo from plant tissues was modified. We demonstrated the Mo-enzyme content assessment by isolated MoCo from the fish's internal organs and the Neurospora crassa nit-1 extract containing inactive NADPH nitrate reductase. The Mo enzyme content was calculated using a calibration curve in nM of nitrites as a product of restored NADPH reductase activity after complementation with MoCo. Here we present a robust laboratory method which can be used to assess the content of Mo-enzymes in the internal organs of fish. • Mo-enzymes play a crucial role in detoxifying toxic compounds. Therefore, it is important to develop a method to accurately determine the amount of Mo-enzymes present. Notably, the method demonstrated the efficiency and accuracy as detected high content of Mo-enzymes in the liver and intestines (P < 0.0001). The obtained data on the distribution of Mo-enzymes in the internal organs of this species correspond to that of other vertebrates. Here, we present a rapid, sensitive, accurate and accessible method. • The developed method is simple and easy to use. Importantly, the protocol does not require complex manipulations, and the equipment used is available in most laboratories. The article provides step-by-step instructions for reproducing the method.

It is generally known that when the grain is primed, saturated with a solution of biologically important elements and subsequently dried, the aleurone layer selectively permits ions of various metals. It is also known that in the case of a deficiency of molybdenum in the soil, a non-molybdenum inactive population of molecules of xanthine dehydrogenase and nitrate reductase is synthesized in plant cells. Presowing priming of wheat grain in molybdate solution of optimal concentration allows grain to germinate more actively. Upon germination of the wheat grain, in the process of embryo cells division, exogenous molybdenum is incorporated into the molecule of the non-molybdenum forms of the newly synthesized molybdoenzymes - nitrate reductase and xanthine dehydrogenase. This leads to the complete activation of the non-molybdenum forms of nitrate reductase and xanthine dehydrogenase in sprouted wheat grain. Since nitrate assimilation induces nitrate reductase synthesis, which uses reduced nicotinamide adenine dinucleotide as donor of electrons, nicotinamide adenine dinucleotide oxidized pool is formed in the cells, what is specifically required for the oxidation of xanthine to allantoin (via uric acid) by xanthine dehydrogenase. Our results show that prior to sowing priming of wheat grain of the "Baiterek" cultivar in molybdate solution and further growth in a nitrate containing medium abruptly increases the content of the antioxidant allantoin in germinated grain.