Effect of Yarrowia lipolytica yeast biomass with increased kynurenic acid content on selected metabolic indicators in mice

Background

The unconventional yeast species Yarrowia lipolytica is a valuable source of protein and many other nutrients. It can be used to produce hydrolytic enzymes and metabolites, including kynurenic acid (KYNA), an endogenous metabolite of tryptophan with a multidirectional effect on the body. The administration of Y. lipolytica with an increased content of KYNA in the diet may have a beneficial effect on metabolism, which was evaluated in a nutritional experiment on mice.

Methods

In the dry biomass of Y. lipolytica S12 enriched in KYNA (high-KYNA yeast) and low-KYNA (control) yeast, the content of KYNA was determined by high-performance liquid chromatography. Then, proximate and amino acid composition and selected indicators of antioxidant status were compared. The effect of 5% high-KYNA yeast content in the diet on the growth, hematological and biochemical indices of blood and the redox status of the liver was determined in a 7-week experiment on adult male mice from an outbred colony derived from A/St, BALB/c, BN/a and C57BL/6J inbred strains.

Results

High-KYNA yeast was characterized by a greater concentration of KYNA than low-KYNA yeast (0.80 ± 0.08 vs. 0.29 ± 0.01 g/kg dry matter), lower content of crude protein with a less favorable amino acid composition and minerals, higher level of crude fiber and fat and lower ferric-reducing antioxidant power, concentration of phenols and glutathione. Consumption of the high-KYNA yeast diet did not affect the cumulative body weight gain per cage, cumulative food intake per cage and protein efficiency ratio compared to the control diet. A trend towards lower mean corpuscular volume and hematocrit, higher mean corpuscular hemoglobin concentration and lower serum total protein and globulins was observed, increased serum total cholesterol and urea were noted. Its ingestion resulted in a trend towards greater ferric-reducing antioxidant power in the liver and did not affect the degree of liver lipid and protein oxidation.

Conclusions

The improvement of the quality of Y. lipolytica yeast biomass with increased content of KYNA, including its antioxidant potential, would be affected by the preserved level of protein and unchanged amino acid profile. It will be worth investigating the effect of such optimized yeast on model animals, including animals with metabolic diseases.

Epibiont Cohabitation in Freshwater Shrimp Neocaridina davidi with the Description of Two Species New to Science, Cladogonium kumaki sp. nov. and Monodiscus kumaki sp. nov., and Redescription of Scutariella japonica and Holtodrilus truncatus

This contribution presents the occurrence of epibiotic species associated with Neocaridina davidi shrimp collected in the wild, aquaculture ponds, and aquaria. A total of 900 shrimp are imported from Taiwan, three-quarters of which host at least one of the recorded epibionts. Among those epibionts, two species new to science are discovered, Cladogonium kumaki sp. nov. and Monodiscus kumaki sp. nov., while the other two, Holtodrilus truncatus and Scutariella japonica, are redescribed. The largest number of epibionts is found in shrimp collected from aquaculture ponds and the lowest in individuals from aquaria. Epibiont occurrence differs across designated microhabitats. The epibionts may be introduced alongside their host outside their native range, and their presence may affect shrimp breeding rates. Thus, more control over them should be provided. Their spread can be limited by removal from the host during molting or manually, as well as by using interspecies interactions.

Effect of radiant catalytic ionization on environmental conditions in rodent rooms and the haematological status of mice

High stocking densities, closed animal houses, and elevated concentrations of bacteria, fungi, and the products of their activity, including ammonia and hydrogen sulphide, have adverse health effects. Active techniques used to reduce unfavourable environmental conditions, such as ventilation, sprinkling, bedding sorbents, and nutritional treatments, are not always sufficient to improve the animals’ living environment. The current paper aims to evaluate the effect of radiant catalytic ionization (RCI) on airborne microorganisms, cage microbiological status, gaseous ammonia concentrations, and the haematological status of mice in animal houses. After one week of operation of an RCI system, the number of airborne bacteria and fungi in the experimental room decreased in comparison to the first day of the experiment (p < 0.05 and p < 0.05 respectively), as did the concentrations of ammonia (p < 0.01) and dust. At the same time, the basic health parameters of the mice, determined in the blood, were very similar between the control and experimental room. RCI seems to be an ideal solution to ensure high hygiene standards in animal rooms and houses with limited use of disinfectants or antibiotic treatment of sick animals. An additional, environmental benefit is the limited amount of nitrogen released.

Radiant catalytic ionization improves the microbiological status of rodent facilities without affecting the prooxidative status of mice

The main microbial contaminants of rooms in which laboratory rodents are housed are bacteria and fungi. Restriction of microbial growth to below threshold levels requires the application of various sophisticated antimicrobial techniques that must be effective and safe for the animals. Some of the most commonly used techniques, including chemical disinfection, ventilation, filtration, sterilization and radiation, are not always sufficiently effective. The aim of the current study was to evaluate the efficacy of a modern technique (i.e. radiant catalytic ionization (RCI)) on the microbiological status of an animal care facility, and the health of the mice housed therein. The experiment, conducted over seven days, compared an experimental room with an RCI system permanently turned on with a negative control room. At the completion of the experiment, the number of bacteria in the RCI room air and on its walls was lower than that in the control room (p < 0.01 in both cases). Values of the basic prooxidative parameter, thiobarbituric acid reactive substances concentration, in tissues of mice from the RCI room were within allowed boundaries. Hence, application of an RCI system proved to be an ideal technique to ensure high hygienic standards in animal rooms without any adverse effects on the animals housed therein.

Amyloidogenic proteins and occurrence of different amyloidosis in different animal species

Amyloidosis is a poly-systemic disease caused by extracellular deposition of biologically inactive amyloid proteins, most often in kidneys, liver, nervous system, thyroid, spleen and heart. Depending on the site of production and deposition they can be classified into causing localised (organ-limited) and systemic amyloidosis. Disturbances in functioning of individual organs occur with an increase of the amount of accumulated protein what in turn may lead to the death of the affected individual. The occurrence of amyloidosis has been reported in human, but in animals, the most common form is AA amyloidosis, while AL amyloidosis is the least common. Due to the fact that symptoms of amyloidosis vary and often resemble those occurring in the course of other diseases, it is difficult to diagnose. Treatment of amyloidosis is aimed at improving functioning of the affected organs, yet the disease is incurable.

The effect of alpha-ketoglutarate (AKG) on the behaviour of ageing laboratory mice

Ageing is a complex physiological process characterized by a gradual decline in cell, tissue and organ function. Consequently, ageing is a major risk factor for cardiovascular disease, diabetes and neurodegenerative disorders. Altered nervous system function can lead to behavioural or psychological disorders. Recent research has shown that alpha ketoglutarate (AKG) is a key intermediate in the Krebs cycle that extends the lifespan of adult animal organisms. The objective of this study was to assess the effect of AKG on the behaviour of laboratory mice in an open field test. The Na-AKG form was found to enhance perceptual-motor exploration in the mice (expressed as the number of rearings), and at the same time to suppress anxiety-related behaviour.