Metabolic Significance of Systemic DHA Deficiency

Fatty acid composition in the body displays a high level of heterogeneity and can rapidly respond to changes in diet regime or to starvation. Homeostasis of the level of certain fatty acids is an important factor for maintenance of structural integrity as well as for proper signaling within the organism. Hence, changes in fatty acid composition have been proposed as an important factor during the pathogenesis of many diseases.Concentration of polyunsaturated fatty acid (PUFA) within the body is modulated by the interplay between dietary intake, endogenous de novo synthesis or mobilization of fatty acids from tissue reservoirs. Endogenous synthesis of PUFA is regulated on different genetic levels as well as the level of substrate availability. Studies have reported a variation in PUFA biosynthesis between different developmental stages, age, gender, during pregnancy, lactation and under conditions of certain disorders. A member of the enzymatic machinery involved in PUFA synthesis is the elongase Elongation of very long-chain fatty acids 2 (ELOVL2) that controls the elongation of PUFA with 22 carbons to produce 24 carbons precursors for the production of the omega-3 PUFA, docosahexaenoic acid (DHA, 22:6n3) and the omega-6 PUFA, docosapentaenoic (DPAn6, 22:5n6). Deletion of Elovl2 in a mouse model (Elovl2KO) leads to systemic DHA deficiency at different physiological and early lifestages, and is related to certain metabolic dysfunctions. Mitochondria of Elovl2KO mice display structural and functional impairment. Compared to wild type littermates, Elovl2KO mice do not gain as much weight after high-fat diet treatment and do not develop hepatic steatosis, despite having a higher level of the positive regulator of denovo lipogenesis, nuclear transcription factor SREBP1c. Resistance to high fat diet induced-obesity in Elovl2KO mice is abolished by DHA supplementation together with high sucrose content in the background diet. In conclusion, deletion of Elovl2 in mice leads to systemic DHA deficiency that has pleiotropic effect on mouse energy metabolism.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p

Determination and Identification of Antibiotic Drugs and Bacterial Strains in Biological Samples

Antibiotics were initially natural substances. However, nowadays, they also include synthetic drugs, which show their activity against bacteria, killing or inhibiting their growth and division. Thanks to these properties, many antibiotics have quickly found practical application in the fight against infectious diseases such as tuberculosis, syphilis, gastrointestinal infections, pneumonia, bronchitis, meningitis and septicemia. Antibiotic resistance is currently a detrimental problem; therefore, in addition to the improvement of antibiotic therapy, attention should also be paid to active metabolites in the body, which may play an important role in exacerbating the existing problem. Taking into account the clinical, cognitive and diagnostic purposes of drug monitoring, it is important to select an appropriate analytical method that meets all the requirements. The detection and identification of the microorganism responsible for the infection is also an essential factor in the implementation of appropriate antibiotic therapy. In recent years, clinical microbiology laboratories have experienced revolutionary changes in the way microorganisms are identified. The MALDI-TOF MS technique may be interesting, especially in some areas where a quick analysis is required, as is the case with clinical microbiology. This method is not targeted, which means that no prior knowledge of the infectious agent is required, since identification is based on a database match

Metabolic Significance of Systemic DHA Deficiency

Fatty acid composition in the body displays a high level of heterogeneity and can rapidly respond to changes in diet regime or to starvation. Homeostasis of the level of certain fatty acids is an important factor for maintenance of structural integrity as well as for proper signaling within the organism. Hence, changes in fatty acid composition have been proposed as an important factor during the pathogenesis of many diseases.Concentration of polyunsaturated fatty acid (PUFA) within the body is modulated by the interplay between dietary intake, endogenous de novo synthesis or mobilization of fatty acids from tissue reservoirs. Endogenous synthesis of PUFA is regulated on different genetic levels as well as the level of substrate availability. Studies have reported a variation in PUFA biosynthesis between different developmental stages, age, gender, during pregnancy, lactation and under conditions of certain disorders. A member of the enzymatic machinery involved in PUFA synthesis is the elongase Elongation of very long-chain fatty acids 2 (ELOVL2) that controls the elongation of PUFA with 22 carbons to produce 24 carbons precursors for the production of the omega-3 PUFA, docosahexaenoic acid (DHA, 22:6n3) and the omega-6 PUFA, docosapentaenoic (DPAn6, 22:5n6). Deletion of Elovl2 in a mouse model (Elovl2KO) leads to systemic DHA deficiency at different physiological and early lifestages, and is related to certain metabolic dysfunctions. Mitochondria of Elovl2KO mice display structural and functional impairment. Compared to wild type littermates, Elovl2KO mice do not gain as much weight after high-fat diet treatment and do not develop hepatic steatosis, despite having a higher level of the positive regulator of denovo lipogenesis, nuclear transcription factor SREBP1c. Resistance to high fat diet induced-obesity in Elovl2KO mice is abolished by DHA supplementation together with high sucrose content in the background diet. In conclusion, deletion of Elovl2 in mice leads to systemic DHA deficiency that has pleiotropic effect on mouse energy metabolism.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 3: Manuscript. Paper 4: Manuscript.</p

Synergistic Effects of DHA and Sucrose on Body Weight Gain in PUFA-Deficient Elovl2 -/- Mice

The omega-3 polyunsaturated fatty acid docosahexaenoic acid (DHA) is implicated in the regulation of both lipid and carbohydrate metabolism. Thus, we questioned whether dietary DHA and low or high content of sucrose impact on metabolism in mice deficient for elongation of very long-chain fatty acids 2 (ELOVL2), an enzyme involved in the endogenous DHA synthesis. We found that Elovl2 -/- mice fed a high-sucrose DHA-enriched diet followed by the high sucrose, high fat challenge significantly increased body weight. This diet affected the triglyceride rich lipoprotein fraction of plasma lipoproteins and changed the expression of several genes involved in lipid metabolism in a white adipose tissue. Our findings suggest that lipogenesis in mammals is synergistically influenced by DHA dietary and sucrose content

Identification, Structure and Characterization of Bacillus tequilensis Biofilm with the Use of Electrophoresis and Complementary Approaches

Biofilm is a complex structure formed as a result of the accumulation of bacterial cell clusters on a surface, surrounded by extracellular polysaccharide substances (EPSs). Biofilm-related bacterial infections are a significant challenge for clinical treatment. Therefore, the main goal of our study was to design a complementary approach in biofilm characterization before and after the antibiotic treatment. The 16S rRNA gene sequencing allowed for the identification of Bacillus tequilensis, as a microbial model of the biofilm formation. Capillary electrophoresis demonstrates the capability to characterize and show the differences of the electrophoretic mobility between biofilms untreated and treated with antibiotics: amoxicillin, gentamicin and metronidazole. Electrophoretic results show the clumping phenomenon (amoxicillin and gentamicin) as a result of a significant change on the surface electric charge of the cells. The stability of the dispersion study, the molecular profile analysis, the viability of bacterial cells and the scanning morphology imaging were also investigated. The microscopic and spectrometry study pointed out the degradation/remodeling of the EPSs matrix, the inhibition of the cell wall synthesis and blocking the ribosomal protein synthesis by amoxicillin and gentamicin. However, untreated and treated bacterial cells show a high stability for the biofilm formation system. Moreover, on the basis of the type of the antibiotic treatment, the mechanism of used antibiotics in cell clumping and degradation were proposed