The effect of antioxidants on xanthine oxidase activity in fresh ovine milk

In the present, the consequences of nitrate pollution of the environment are very pronounced. In humans and animals, microorganisms can reduce nitrates to nitrites, which cause cancer. Purified and homogeneous xanthine oxidase (XO) of cow's milk can restore these compounds, which makes the article extremely relevant. The purpose of the article is to determine the effect of antioxidants on the activity of xanthine oxidase in fresh ovine milk. Various natural and artificial antioxidants were examined for the detection of xanthine oxidase (XO) activity in ovine milk. Among the natural antioxidants, L-cysteine was more effective in the stabilization of XO in heated milk. XO of sheep milk activated by heat treatment in the presence of cysteine and molybdenum became able to convert nitrate and nitrite to nitric oxide (NO). Therefore, L-cysteine was used for double purposes: as the protector of enzyme active center against the oxidation during heat treatment of milk and as a reagent for S-nitrosothiol formation. Hypoxanthine, as a natural substrate of XO, is an effective electron donor for nitrate reductase (NR) and nitrite reductase (NiR) activities. Heat treatment of the milk in the presence of exogenous lecithin increased the activity of NR and NiR of XO and CysNO formation. Thus, during the heat treatment: a) excess of exogenous phospholipids disintegrates the structure of milk fat globule membrane (MFGM) and b) enzyme molecules denatured partially and their active center became available for exogenous cysteine, molybdenum, hypoxanthine, and nitrate or nitrite.

Light optical and Ultrastructural Characteristics of the Maral Liver with Chronic Dicrocoeliasis

BACKGROUND: Dicrocoeliasis is caused by trematode Dicrocoelium lanceatum from the family Dicrocoeliidae, a parasite in the bile ducts of the liver of domestic and wild animals. Dicrocoeliasis mainly affects sheep, cattle, camels, zebu, deer, fallow deer, argali, less often – horses, donkeys, dogs, rabbits, hares and bears, as well as humans. Dicrocoeliasis of ruminants is widespread across the whole Kazakhstan. Invasive diseases represent a significant obstacle in the development of domestic maral breeding, among which trematodoses, and particularly dicrocoeliasis of maral play a major role. AIM: The aim of the research was to study the influence of dicrocoelia on the ultrastructural organization of the liver of maral. MATERIALS AND METHODS: For examination under electron microscope, biopsy pieces of liver tissue of maral were fixed in 2.5% solution of glutaraldehyde with post-fixation in 1% solution of osmium tetroxide, conducted according to a conventional method, and enclosed in epon. Semi-thin and ultra-thin sections were prepared on the ultra-microtome Leica. Semi-thin sections were stained with methylene blue, azure 2, and studied at a high-resolution light optical level. The ultra-thin sections were contrasted with uranyl acetate and lead citrate according Reynolds method and examined under electron microscope Libra 120 (C. Zeiss). RESULTS: The light optical examination of half-thin sections revealed that the morphological pattern of pathological changes in liver tissue was polymorphic, even within a single hepatic lobe. CONCLUSIONS: In the liver of maral infected with chronic dicrocoeliasis, dystrophic and destructive pathological changes developed in all the cellular structures of the hepatic lobules: In the form of plethora and vast enlargement of sinusoids, vacuolar and lipodegeneration of hepatocytes, destruction of the hepatic tissue with edema, hemorrhages, in the appearance of cells associated with inflammation, and the deposition of hematin crystals.

Method for assessing the content of molybdenum enzymes in the internal organs of fish

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.