Membrane Sterol Research Articles

Altered sterol composition mediates multiple tolerance of Kluyveromyces marxianus for xylitol production

BackgroundCurrently, the synthesis of compounds based on microbial cell factories is rapidly advancing, yet it encounters several challenges. During the production process, engineered strains frequently encounter disturbances in the cultivation environment or the impact of their metabolites, such as high temperature, acid-base imbalances, hypertonicity, organic solvents, toxic byproducts, and mechanical damage. These stress factors can constrain the efficiency of microbial fermentation, resulting in slow cell growth, decreased production, significantly increased energy consumption, and other issues that severely limit the application of microbial cell factories.ResultsThis study demonstrated that sterol engineering in Kluyveromyces marxianus, achieved by overexpressing or deleting the coding genes for the last five steps of ergosterol synthase (Erg2-Erg6), altered the composition and ratio of sterols in its cell membrane, and affected its multiple tolerance. The results suggest that the knockout of the Erg5 can enhance the thermotolerance of K. marxianus, while the overexpression of the Erg4 can improve its acid tolerance. Additionally, engineering strain overexpressed Erg6 improved its tolerance to elevated temperature, hypertonic, and acid. YZB453, obtained by overexpressing Erg6 in an engineering strain with high efficiency in synthesizing xylitol, produced 101.22 g/L xylitol at 45oC and 75.11 g/L xylitol at 46oC. Using corncob hydrolysate for simultaneous saccharification and fermentation (SSF) at 46oC that xylose released from corncob hydrolysate by saccharification with hemicellulase, YZB453 can produce 45.98 g/L of xylitol, saving 53.72% of the cost of hemicellulase compared to 42oC.ConclusionsThis study elucidates the mechanism by which K. marxianus acquires resistance to various antifungal drugs, high temperatures, high osmolarity, acidity, and other stressors, through alterations in the composition and ratio of membrane sterols. By employing sterol engineering, the fermentation temperature of this unconventional thermotolerant K. marxianus was further elevated, ultimately providing an efficient platform for synthesizing high-value-added xylitol from biomass via the SSF process at temperatures exceeding 45 °C.

Comparing ergosterol identification by HPLC with fungal serology in human sera

BackgroundErgosterol, a predominant sterol in fungal cell membranes, holds promise as a specific marker for detecting fungal presence in human samples. This study investigated the performance of ergosterol detection compared to serological tests in identifying the presence of fungi in human sera. MethodsEighty-four non-duplicate human sera were analyzed by high performance liquid chromatography (HPLC) for ergosterol detection. Results were compared to serological tests for Aspergillus antigen, Candida antigen, Cryptococcus antigen, Aspergillus antibody and Candida antibody performed on the same patient sera. ResultsOut of the 84 serum samples, 51 (60.7 %) were positive for ergosterol. Among the 33 serology-positive sera, 26 (78.8 %) were also ergosterol-positive. In contrast, 26 out of 51 (51 %) serology-negative sera (including 20 negative controls) tested negative for ergosterol. Seven out of 33 (21.2 %) serology-positive sera were ergosterol-negative, while 25 out of 51 (49 %) serology-negative sera were ergosterol-positive. Compared to serological tests, HPLC detection of ergosterol had a sensitivity of 78.8 %, specificity of 51 %, positive predictive value of 51 %, negative predictive value of 78.8 % and overall accuracy of 61.9 %. ConclusionsErgosterol detection may serve as a useful supplementary tool for identifying fungi in human sera, acting as a broad-spectrum diagnostic marker. However, further research with larger sample sizes and clinical comparisons is needed to validate these findings.

Topological Learning Approach to Characterizing Biological Membranes.

Biological membranes play key roles in cellular compartmentalization, structure, and its signaling pathways. At varying temperatures, individual membrane lipids sample from different configurations, a process that frequently leads to higher-order phase behavior and phenomena. Here, we present a persistent homology (PH)-based method for quantifying the structural features of individual and bulk lipids, providing local and contextual information on lipid tail organization. Our method leverages the mathematical machinery of algebraic topology and machine learning to infer temperature-dependent structural information on lipids from static coordinates. To train our model, we generated multiple molecular dynamics trajectories of dipalmitoyl-phosphatidylcholine membranes at varying temperatures. A fingerprint was then constructed for each set of lipid coordinates by PH filtration, in which interaction spheres were grown around the lipid atoms while tracking their intersections. The sphere filtration formed a simplicial complex that captures enduring key topological features of the configuration landscape using homology, yielding persistence data. Following fingerprint extraction for physiologically relevant temperatures, the persistence data were used to train an attention-based neural network for assignment of effective temperature values to selected membrane regions. Our persistence homology-based method captures the local structural effects, via effective temperature, of lipids adjacent to other membrane constituents, e.g., sterols and proteins. This topological learning approach can predict lipid effective temperatures from static coordinates across multiple spatial resolutions. The tool, called MembTDA, can be accessed at https://github.com/hyunp2/Memb-TDA.

Mechanism and bioinformatics analysis of the effect of berberine-enhanced fluconazole against drug-resistant Candida albicans

Biofilms produced by Candida albicans present a challenge in treatment with antifungal drug. Enhancing the sensitivity to fluconazole (FLC) is a reasonable method for treating FLC-resistant species. Moreover, several lines of evidence have demonstrated that berberine (BBR) can have antimicrobial effects. The aim of this study was to clarify the underlying mechanism of these effects. We conducted a comparative study of the inhibition of FLC-resistant strain growth by FLC treatment alone, BBR treatment alone, and the synergistic effect of combined FLC and BBR treatment. Twenty-four isolated strains showed distinct biofilm formation capabilities. The antifungal effect of combined FLC and BBR treatment in terms of the growth and biofilm formation of Candida albicans species was determined via checkerboard, time-kill, and fluorescence microscopy assays. The synergistic effect of BBR and FLC downregulated the expression of the efflux pump genes CDR1 and MDR, the hyphal gene HWP1, and the adhesion gene ALS3; however, the gene expression of the transcriptional repressor TUP1 was upregulated following treatment with this drug combination. Furthermore, the addition of BBR led to a marked reduction in cell surface hydrophobicity. To identify resistance-related genes and virulence factors through genome-wide sequencing analysis, we investigated the inhibition of related resistance gene expression by the combination of BBR and FLC, as well as the associated signaling pathways and metabolic pathways. The KEGG metabolic map showed that the metabolic genes in this strain are mainly involved in amino acid and carbon metabolism. The metabolic pathway map showed that several ergosterol (ERG) genes were involved in the synthesis of cell membrane sterols, which may be related to drug resistance. In this study, BBR + FLC combination treatment upregulated the expression of the ERG1, ERG3, ERG4, ERG5, ERG24, and ERG25 genes and downregulated the expression of the ERG6 and ERG9 genes compared with fluconazole treatment alone (p < 0.05).

Potential Anemia as a Risk Factor for Angular Cheilitis and Pseudomembranous Candidiasis: Case Report

Angular cheilitis and pseudomembranous candidiasis are oral infections caused by Candida albicans. Angular cheilitis patients also experience oral candidiasis because the Candida reservoir is intraoral. Iron deficiency anemia was closely related to this infection. A 50-year-old female patient complaint of pain in the commissure and tongue 3 weeks ago. Extraoral examination showed anemic conjunctiva and fissure erythema with crusting in bilateral commissures. Intraoral examination showed atrophy of papillae with a yellowish-white plaque that can be scraped off and leaves erythema on the tongue. A complete blood examination was performed and showed a decrease in hemoglobin, hematocrit, erythrocytes, MCV, MCH, and MCHC. The patient was diagnosed angular cheilitis and pseudomembranous candidiasis with iron deficiency anemia. The therapy was miconazole 2% cream, nystatin oral suspension 100.000 IU/ml, and iron supplements. The lesions healed after 2 weeks of therapy and the patient was consulted to an internist. The patient has Angular cheilitis and pseudomembranous candidiasis triggered by iron deficiency anemia. Iron deficiency anemia causes a decrease in salivary transferrin protein which is fungistatic so that Candida grows excessively. Angular Cheilitis therapy is miconazole cream which inhibit the synthesis of ergosterol and nystatin for candidiasis therapy which works by binding to Candida plasma membrane sterols, causing leakage and then death. Iron deficiency anemia therapy is iron supplements; however, drug therapy alone is less effective, and consultation with an internist is required for further therapy. Anemia has big potential to be a risk factor for angular cheilitis and pseudomembranous candidiasis so comprehensive treatment is needed.

Comparison of structural effects of cholesterol, lanosterol, and oxysterol on phospholipid (POPC) bilayers

Membrane sterols contribute to the function of biomembranes by regulating the physical properties of the lipid bilayers. Cholesterol, a typical mammalian sterol, is biosynthesized by oxidation of lanosterol. From a molecular evolutionary perspective, lanosterol is considered the ancestral molecule of cholesterol. Here, we studied whether cholesterol is superior to lanosterol in regulating the physical properties of the lipid bilayer in terms of the structural effect on model biomembranes composed of a phospholipid. For comparison, oxysterol, which is formed by oxidation of cholesterol, was also studied. The phospholipid used was 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), which is abundantly found in mammalian biomembranes, and 7β-hydroxycholesterol, which is highly cytotoxic, was used as the oxysterol. The apparent molecular volume was calculated from the mass density determined by the flotation method using H2O and D2O, and the bilayer thickness was determined by reconstructing the electron density distribution from X-ray diffraction data of the POPC/sterol mixtures at a sterol concentration of 30 mol%. The apparent occupied area at the bilayer surface was calculated from the above two structural data. The cholesterol system had the thickest bilayer thickness and the smallest occupied area of the three sterols studied here. This indicates that the POPC/cholesterol bilayer has a better barrier property than the other two systems. Compared to cholesterol, the effects of lanosterol and 7β-hydroxycholesterol on lipid bilayer properties can be interpreted as suboptimal for the function of mammalian biomembranes.

Ergosterol Is Critical for Sporogenesis in Cryptococcus neoformans.

Microbes, both bacteria and fungi, produce spores to survive stressful conditions. Spores produced by the environmental fungal pathogen Cryptococcus neoformans serve as both surviving and infectious propagules. Because of their importance in disease transmission and pathogenesis, factors necessary for cryptococcal spore germination are being actively investigated. However, little is known about nutrients critical for sporogenesis in this pathogen. Here, we found that ergosterol, the main sterol in fungal membranes, is enriched in spores relative to yeasts and hyphae. In C. neoformans, the ergosterol biosynthesis pathway (EBP) is upregulated by the transcription factor Sre1 in response to conditions that demand elevated ergosterol biosynthesis. Although the deletion of SRE1 enhances the production of mating hyphae, the sre1Δ strain is deficient at producing spores even when crossed with a wild-type partner. We found that the defect of the sre1Δ strain is specific to sporogenesis, not meiosis or basidium maturation preceding sporulation. Consistent with the idea that sporulation demands heightened ergosterol biosynthesis, EBP mutants are also defective in sporulation. We discovered that the overexpression of some EBP genes can largely rescue the sporulation defect of the sre1Δ strain. Collectively, we demonstrate that ergosterol is a critical component in cryptococcal preparation for sporulation.

Identification of squalene epoxidase in triterpenes biosynthesis in Poria cocos by molecular docking and CRISPR-Cas9 gene editing

BackgroundSqualene epoxidase is one of the rate-limiting enzymes in the biosynthetic pathway of membrane sterols and triterpenoids. The enzyme catalyzes the formation of oxidized squalene, which is a common precursor of sterols and triterpenoids.ResultIn this study, the squalene epoxidase gene (PcSE) was evaluated in Poria cocos. Molecular docking between PcSE and squalene was performed and the active amino acids were identified. The sgRNA were designed based on the active site residues. The effect on triterpene synthesis in P. cocos was consistent with the results from ultra-high-performance liquid chromatography-quadruplex time-of-flight-double mass spectrometry (UHPLC-QTOF-MS/MS) analysis. The results showed that deletion of PcSE inhibited triterpene synthesis. In vivo verification of PcSE function was performed using a PEG-mediated protoplast transformation approach.ConclusionThe findings from this study provide a foundation for further studies on heterologous biosynthesis of P. cocos secondary metabolites.

Deletion of the Candida albicans TLO gene family results in alterations in membrane sterol composition and fluconazole tolerance.

Development of resistance and tolerance to antifungal drugs in Candida albicans can compromise treatment of infections caused by this pathogenic yeast species. The uniquely expanded C. albicans TLO gene family is comprised of 14 paralogous genes which encode Med2, a subunit of the multiprotein Mediator complex which is involved in the global control of transcription. This study investigates the acquisition of fluconazole tolerance in a mutant in which the entire TLO gene family has been deleted. This phenotype was reversed to varying degrees upon reintroduction of representative members of the alpha- and beta-TLO clades (i.e. TLO1 and TLO2), but not by TLO11, a gamma-clade representative. Comparative RNA sequencing analysis revealed changes in the expression of genes involved in a range of cellular functions, including ergosterol biosynthesis, mitochondrial function, and redox homeostasis. This was supported by the results of mass spectrometry analysis, which revealed alterations in sterol composition of the mutant cell membrane. Our data suggest that members of the C. albicans TLO gene family are involved in the control of ergosterol biosynthesis and mitochondrial function and may play a role in the responses of C. albicans to azole antifungal agents.

LAMinar Flow: Sterol Transport in a Pathogenic Yeast.

Cryptococcus neoformans is an important fungal pathogen, responsible for over 140,000 deaths per year worldwide. Like other yeasts, C. neoformans relies on ergosterol as its major membrane sterol and carefully regulates its synthesis and distribution. Ergosterol is also targeted by two of the three compound classes currently used to treat cryptococcal infection. We recently reported the discovery and characterization in C. neoformans of a single retrograde ergosterol transporter of the LAM family, Ysp2. Here we review these findings and discuss directions for future research, including the connections between processes that are perturbed by the absence of Ysp2 (which also abrogates cryptococcal virulence) and possible roles for Ysp2 and other, as yet unknown, lipid transport proteins in this organism.

Metabolism of Lumisterol2 by CYP27A1

Lumisterol2 (L2) is a photoproduct of UVB action on the fungal membrane sterol, ergosterol. Like vitamin D2, it is present in edible mushrooms, especially after UV irradiation. Lumisterol3 is similarly produced in human skin from 7-dehydrocholesterol by UVB and can be converted to hydroxy-metabolites by CYP27A1 and CYP11A1. These products are biologically active on human cells with actions that include photoprotection and inhibition of proliferation. The aim of this study was to test the ability of CYP11A1 and CYP27A1 to metabolise L2. Purified CYP27A1 was found to efficiently metabolise L2 to three major products and several minor products, whilst CYP11A1 did not act appreciably on L2. The three major products of CYP27A1 action on L2 were identified by mass spectrometry and NMR as 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2. Minor products included two dihydroxy L2 species, one which was identified as 24,27(OH)2L2, and another metabolite with one oxo and one hydroxyl group added. A comparison on the kinetics of the metabolism of L2 by CYP27A1 with that of the structurally similar compounds, L3 and ergosterol, was carried out with substrates incorporated into phospholipid vesicles. CYP27A1 displayed a 12-fold lower Km with L2 as substrate compared to L3 and a 5-fold lower turnover number (kcat), resulting in a 2.2 fold higher catalytic efficiency (kcat/Km) for L2 metabolism. L2 was a much better substrate for CYP27A1 than its precursor, ergosterol, with a catalytic efficiency 18-fold higher. The major CYP27A1-derived hydroxy-L2 products, 24-hydroxyL2, 27-hydroxyL2 and 28-hydroxyL2, inhibited the proliferation of melanoma and epidermoid cancer cell lines. In conclusion, this study shows that L2 is not metabolized appreciably by CYP11A1, but it is a good substrate for CYP27A1 which hydroxylates its side chain to produce 3 major products that display anti-proliferative activity on skin-cancer cell lines.

Ergosterol distribution controls surface structure formation and fungal pathogenicity.

Ergosterol, the major sterol in fungal membranes, is critical for defining membrane fluidity and regulating cellular processes. Although ergosterol synthesis has been well defined in model yeast, little is known about sterol organization in the context of fungal pathogenesis. We identified a retrograde sterol transporter, Ysp2, in the opportunistic fungal pathogen Cryptococcus neoformans. We found that the lack of Ysp2 under host-mimicking conditions leads to abnormal accumulation of ergosterol at the plasma membrane, invagination of the plasma membrane, and malformation of the cell wall, which can be functionally rescued by inhibiting ergosterol synthesis with the antifungal drug fluconazole. We also observed that cells lacking Ysp2 mislocalize the cell surface protein Pma1 and have abnormally thin and permeable capsules. As a result of perturbed ergosterol distribution and its consequences, ysp2∆ cells cannot survive in physiologically relevant environments such as host phagocytes and are dramatically attenuated in virulence. These findings expand our knowledge of cryptococcal biology and underscore the importance of sterol homeostasis in fungal pathogenesis. IMPORTANCE Cryptococcus neoformans is an opportunistic fungal pathogen that kills over 100,000 people worldwide each year. Only three drugs are available to treat cryptococcosis, and these are variously limited by toxicity, availability, cost, and resistance. Ergosterol is the most abundant sterol in fungi and a key component in modulating membrane behavior. Two of the drugs used for cryptococcal infection, amphotericin B and fluconazole, target this lipid and its synthesis, highlighting its importance as a therapeutic target. We discovered a cryptococcal ergosterol transporter, Ysp2, and demonstrated its key roles in multiple aspects of cryptococcal biology and pathogenesis. These studies demonstrate the role of ergosterol homeostasis in C. neoformans virulence, deepen our understanding of a pathway with proven therapeutic importance, and open a new area of study.

Elucidation of furanone as ergosterol pathway inhibitor in Cryptococcus neoformans

In the era of antiretroviral therapy, the prevalence of Cryptococcal infection among HIV patients in developed countries has decreased considerably. However, C. neoformans ranks top among the critical priority pathogen that affects a wide range of immunocompromised individuals. The threat of C. neoformans is because of its incredibly multifaceted intracellular survival capabilities. Cell membrane sterols especially ergosterol and enzymes of its biosynthetic pathway are considered fascinating drug targets because of their structural stability. In this study, the ergosterol biosynthetic enzymes were modeled and docked with furanone derivatives. Among the tested ligands Compound 6 has shown a potential interaction with Lanosterol 14 α-demethylase. This best-docked protein-ligand complex was taken further to molecular dynamics simulation. In addition, Compound 6 was synthesized and an in vitro study was conducted to quantify the ergosterol in Compound 6 treated cells. Altogether the computational and in vitro study demonstrates that Compound 6 has anticryptococcal activity by targeting the biosynthetic pathway of ergosterol. Communicated by Ramaswamy H. Sarma

Comparison of Changes in the Content of Plasma Membrane and Tonoplast Sterols under Oxidative and Osmotic Stress

Comparison of Changes in the Content of Plasma Membrane and Tonoplast Sterols under Oxidative and Osmotic Stress

Increase in steryl glycoside levels and stimulation of lipid raft formation in azuki bean epicotyls under hypergravity conditions

Sterols are the main components of the plasma membrane and are involved in various plant membrane functions. Azuki bean (Vigna angularis (Wild.) Ohwi et Ohashi) seedlings were cultivated under hypergravity conditions, and changes in the levels and composition of membrane sterols in their epicotyls were analyzed. Under hypergravity conditions at 300 g, the levels of steryl glycosides and acyl steryl glycosides per unit length and per gram fresh weight greatly increased, which accounted for an increase in the total sterol levels. Stigmasterol, β-sitosterol, and campesterol were the most abundant sterols. Hypergravity decreased the proportion of stigmasterol but increased that of β-sitosterol. The fatty chains of acyl steryl glycosides mainly consisted of palmitic acid (C16:0), stearic acid (C18:0), linoleic acid (C18:2), and α-linolenic acid (C18:3), and their proportions were not modified under hypergravity conditions. In addition, the density of membrane microdomains, visualized with anti-Flotillin 1 antibody per unit area, increased by hypergravity, suggesting that lipid raft formation was stimulated. These results support the hypothesis that lipid rafts are involved in plant response and resistance to gravity.

Membrane Lipids in Ultra-High-Risk Patients: Potential Predictive Biomarkers of Conversion to Psychosis

Alterations in membrane lipids are reported in schizophrenia. However, no conclusion can be drawn regarding the extended and predictive value of these alterations in persons at ultra-high risk of psychosis (UHR). Recent studies suggested that sterols’ impact on psychiatric disorders was underestimated. Here, we simultaneously explored sterols, fatty acids (FA), and phospholipids (PL) in UHR persons for the first time. We analysed erythrocyte membrane lipids in 61 UHR persons, including 29 who later converted to psychosis (UHR-C) and 32 who did not (UHC-NC). We used gas chromatography for FA and liquid chromatography tandem with mass spectrometry for sterols and phospholipids. Among UHR individuals, elevated baseline membrane linoleic acid level was associated with conversion to psychosis (26.1% vs. 60.5%, p = 0.02). Combining sterols, FA, and PL membrane composition improved the prediction of psychosis onset (AUC = 0.73). This is the first report showing that membrane sterol participates, with other membrane lipids, in modulating the risk of psychosis. It suggests that membrane lipids could be used as biomarkers for personalised medicine in UHR patients.

The Antileishmanial Activity of Eugenol Associated with Lipid Storage Reduction Rather Than Membrane Properties Alterations.

Leishmaniasis is a neglected tropical disease that still infects thousands of people per year throughout the world. The occurrence of resistance against major treatments for this disease causes a healthcare burden in low-income countries. Eugenol is a phenylpropanoid that has shown in vitro antileishmanial activity against Leishmania mexicana mexicana (Lmm) promastigotes with an IC50 of 2.72 µg/mL and a high selectivity index. Its specific mechanism of action has yet to be studied. We prepared large unilamellar vesicles (LUVs), mimicking Lmm membranes, and observed that eugenol induced an increase in membrane permeability and a decrease in membrane fluidity at concentrations much higher than IC50. The effect of eugenol was similar to the current therapeutic antibiotic, amphotericin B, although the latter was effective at lower concentrations than eugenol. However, unlike amphotericin B, eugenol also affected the permeability of LUVs without sterol. Its effect on the membrane fluidity of Lmm showed that at high concentrations (≥22.5× IC50), eugenol increased membrane fluidity by 20-30%, while no effect was observed at lower concentrations. Furthermore, at concentrations below 10× IC50, a decrease in metabolic activity associated with the maintenance of membrane integrity revealed a leishmaniostatic effect after 24 h of incubation with Lmm promastigotes. While acidocalcisomes distribution and abundance revealed by Trypanosoma brucei vacuolar H+ pyrophosphatase (TbVP1) immunolabeling was not modified by eugenol, a dose-dependent decrease of lipid droplets assessed by the Nile Red assay was observed. We hereby demonstrate that the antileishmanial activity of eugenol might not directly involve plasma membrane sterols such as ergosterol, but rather target the lipid storage of Lmm.

Characterization of Non-Cholesterol Sterols in Microglia Cell Membranes Using Targeted Mass Spectrometry.

Non-cholesterol sterols, as well as plant sterols, cross the blood-brain barrier and, thus, can be incorporated into cell membranes, affecting the cell's inflammatory response. The aim of our work was to develop an analytical protocol for a quantitative assessment of the sterol composition within the membrane microdomains of microglia. A protocol for cell membrane isolation using OptiPrepTM gradient ultracentrifugation, in combination with a targeted mass spectrometry (LC-MS/MS)-based assay, was developed and validated for the quantitative analysis of free sterols in microglia cell membranes. Utilizing an established LC-MS/MS assay, cholesterol and seven non-cholesterol sterols were analyzed with a limit of detection from 0.001 to 0.05 mg/L. Applying the detergent-free isolation of SIM-A9 microglia cell membranes, cholesterol (CH), desmosterol (DE), lanosterol (LA) stigmasterol (ST), beta-sitosterol (SI) and campesterol (CA) were quantified with coefficients of variations between 6 and 29% (fractions 4-6, n = 5). The highest concentrations of non-CH sterols within the microglia plasma membranes were found in the microdomain region (DE>LA>SI>ST>CA), with ratios to CH ranging from 2.3 to 435 lower abundancies. By applying our newly developed and validated analytical protocol, we show that the non-CH sterol concentration is about 38% of the total sterol content in microglia membrane microdomains. Further investigations must clarify how changes in the non-sterol composition influence membrane fluidity and cell signaling.

Effects of Trehalose Supplementation on Lipid Composition of Rooster Spermatozoa Membranes in a Freeze/Thaw Protocol.

The plasma membrane of spermatozoa plays an important role in the formation and maintenance of many functions of spermatozoa, including during cryopreservation. As a result of chromatographic analysis, the content of lipids and fatty acids in the membranes of spermatozoa of roosters of two breeds was determined under the influence of cryoprotective media containing trehalose LCM-control (0 mM), Treh20 (9.5 mM), and Treh30 (13.4 mM). The use of the cryoprotective diluent Treh20 made it possible to maintain a dynamic balance between the synthesis and degradation of phospholipids and sterols in the plasma membranes of frozen/thawed spermatozoa, close to that of native spermatozoa. This contributed to an increase in the preservation of frozen/thawed spermatozoa membranes from 48.3% to 52.2% in the egg breed and from 30.0% to 35.1% in the meat- and-egg breed. It was also noted that their kinetic apparatus (mobility indicators) remained at the level of 45.6% (egg breed) and 52.4% (meat-and-egg breed). An increase in the concentration of trehalose to 13.4 mM in a cryoprotective diluent for rooster sperm resulted in a decrease in the morphofunctional parameters of frozen/thawed spermatozoa.

Comparison of Changes in the Content of Plasma Membrane and Tonoplast Sterols under Oxidative and Osmotic Stress

Comparison of Changes in the Content of Plasma Membrane and Tonoplast Sterols under Oxidative and Osmotic Stress