Changes in the lipid composition of Mucor hiemalis sporangiospores related to the age of the spore-forming culture

Analysis of sporangiospore lipids of the fungus Mucor hiemalis F-1156 showed that alterations occur in the content of fatty acids and individual classes of lipids during long-term cultivation (for about 20 days). The changes in the lipid composition related to the age of the spore-forming mycelium suggest an important role of sporangiospore lipids in spore germination and in further development of the spherical cells formed in this processes. The M. hiemalis F-1156 sporangiospores with a lipid pool exhausted during long-term cultivation can give rise to both mycelial and yeastlike growth.     

Synthesis of Biologically Active Lipids by the Fungus Mucor lusitanicus 306D Grown on Media with Various Composition

Growth and lipogenesis of the fungusMucor lusitanicus306D, producing -linoleic acid, was studied under various conditions of nitrogen and carbon nutrition. Media containing food-industry wastes, such as maize extract, molasses, and protein hydrolysate, were used. The content of -linoleic acid was higher when carbohydrates (glucose and molasses) were used as carbon sources and urea was used as a nitrogen source. At a high glucose concentration (100 g/l), fed batch cultivation ensured high contents of -linoleic acid in lipids (1 g/l). After extraction of lipids, the fungus biomass was 42% protein, containing all essential amino acids. A defatted biomass was shown to be effectively assimilated by minks.     

Effect of Energy Under-Reporting on Secular Trends of Dietary Patterns in a Mediterranean Population

BackgroundDiet is an important factor in the prevention of chronic diseases. Analysis of secular trends of dietary patterns can be biased by energy under-reporting. Therefore, the objective of the present study was to analyse the impact of energy under-reporting on dietary patterns and secular trends in dietary patterns defined by cluster analysis.ResultsThree clusters, “healthy”, “mixed” and “western”, were identified for both surveys. The “mixed” cluster was the predominant cluster in both surveys. Excluding EUR reduced the proportion of the “mixed” cluster up to 6.40% in the 2000 survey; this caused secular trend increase in the prevalence of the “mixed” pattern. Cross-classification analysis of all participants and PER’ data showed substantial agreement in cluster assignments: 68.7% in 2000 and 84.4% in 2005. Excluding EUR did not cause meaningful (≥15%) changes in the “healthy” pattern. It provoked changes in consumption of some food groups in the “mixed” and “western” patterns: mainly decreases of unhealthy foods within the 2000 and increases of unhealthy foods within the 2005 surveys. Secular trend effects of EUR were similar to those within the 2005 survey. Excluding EUR reversed the direction of secular trends in consumption of several food groups in PER in the “mixed” and “western” patterns.ConclusionsEUR affected distribution of participants between dietary patterns within and between surveys, secular trends in food group consumption and amount of food consumed in all, but not in the “healthy” pattern. Our findings emphasize threats from energy under-reporting in dietary data analysis.     

Sporangiospore lipids of the mycelial fungus <Emphasis Type="Italic">Mucor ramannianus</Emphasis> incapable of dimorphic growth

Members of the species Mucor ramannianus are believed to be monomorphic. They grow only as a mycelium and are not capable of growth as budding cells, i.e., of dimorphic growth. In our study, we investigated the lipid composition of M. ramannianus sporangiospores, which retained the capability of initiating mycelial growth in the course of long-term cultivation of the spore-forming mycelium. It was demonstrated that sporangiospores contained high concentrations of triacylglycerides (TAG) in their reserve lipids and high concentrations of phosphatidylcholine (PC) in their membrane lipids; low concentrations of methylated ergosterol precursors were detected among sterols. On the basis of the data presented, in order to evaluate the potential of mucor fungi for yeastlike growth, it has been suggested to analyze the qualitative and quantitative characteristics of their sporangiospore lipids and to consider the following criteria as the criteria of sporangiospore capacity for giving rise to yeastlike growth upon spore germination: (1) the phosphatidylethanolamine/phosphatidylcholine (PE/PC) ratio; (2) the level of ergosterol and the ratio between the methylated and demethylated sterols; as well as (3) the ratios between phospholipids and glycolipids (PL/GL) and (4) between etherified and free sterols (ES/FS).     

The role of sterols in morphogenetic processes and dimorphism in fungi

The review considers the fundamental biological problem of fungal dimorphism as an adaptive reaction to adverse impacts. Primary attention is paid to sterols, phospholipids, storage lipids, and fatty acids. The structural and biological functions of sterols are considered, as well as their role in membrane stabilization under stress and their relation to morphogenetic processes in mycelial fungi, of which many are pathogenic. Data on the biosynthesis of the main fungal sterol, ergosterol, are presented, as well as data on the inhibitors of this process and on the mutants deficient in its particular stages. Ergosterol biosynthesis is also considered in terms of its relation to the composition of the fungal cell wall, which is the cell shape-determining structure, and to the intensity of chitin synthesis, a process in which azole derivatives play a role. Data obtained by the authors are presented that show the role of changes in the composition of sterols, phospholipids, storage lipids, and unsaturated fatty acids of resting cells in the induction of yeastlike growth in mucoraceous fungi.     

Metabolic characteristics and lipid composition of yeastlike cells and mycelium of Mucor circinelloides var. lusitanicus INMI grown at a high glucose content in the medium

It is shown that the fungus Mucor circinelloides var. lusitanicus INMI grown under aerobic conditions in a medium with a high glucose concentration (20%) is capable of both yeastlike and mycelial growth. In the mycelium, the activity of NAD-dependent isocitrate dehydrogenase was more than twice as high as in yeastlike cells, whereas the isocitrate lyase activity was lower. A number of significant differences were found in the lipid composition of the cells of two different morphological variants. Yeastlike cells contained more polar lipids and free fatty acids and less principal reserve lipids (triacylglycerides) than mycelial cells; the content of gamma-linolenic acid and the degree of lipid unsaturation were significantly lower in these cells than in the mycelium. In yeastlike cells, glycolipids composed the bulk of polar lipids; the proportion of phospholipids (primarily phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and cardiolipin) was lower. The relationship between cellular metabolism and the lipid composition of fungal cells of different morphotypes grown at high concentrations of glucose, one of the main inducers of dimorphic growth, is discussed.     

Sterol Composition of the Arthrospores and Mycelium of the Fungus Mucor hiemalis

Sterol composition of the arthrospores and mycelium of the fungus Mucor hiemalis 1156 was studied by the method of chromatography–mass spectrometry. Along with ergosterol, the major sterol of the culture studied, ten minor sterols were identified, which were either precursors or products of ergosterol degradation. The content of individual sterols differed substantially in arthrospores and mycelium, which represent different stages of ontogenetic development of the fungus. In arthrospores, the content of ergosterol was lower than in mycelium (55.9 and 78.0%, respectively). Among the precursors of ergosterol, methylated sterols predominated in arthrospores (24.1% versus 11.6% in mycelium). Eburicol and 4,4-dimethylfecosterol were the major methylated sterols of arthrospores (10.6 and 8.1%, respectively). In addition, two uncommon and extremely rare sterols, 1-dihydro-dehydroneoergosterol and dehydroneoergosterol, were identified (for the first time in M. hiemalis). These substances, containing a complex system of conjugated double bonds in their A and B rings, are the products of ergosterol degradation. The data on sterol composition are discussed in terms of their morphogenetic implication.     

Effects of conditions for obtaining sporangiospores of the inoculum on the morphology and productivity of the fungus Mucor circinelloides var. lusitanicus 12 M, a producer of gamma-linolenic acid

Effects of lipid composition of sporangiospores of the fungus Mucor circinelloides var. lusitanicus 12 M, obtained within diverse time frames using distinct nutritive media, on the morphology of the fungus in submerged cultures, the yield of the biomass, and its content of gamma-linolenic acid have been studied. The levels of base phospholipids and individual fractions of neutral lipids in sporangiospores were correlated with the character of their germination. The spores characterized by a high rate of germination and giving rise to a well-developed mycelium contained more phosphatidylcholine and phosphatidylserine, but the level of diacylglycerols was low. An increase in diacylglycerols, free fatty acids, and sterols in lipids of sporangiospores of the inoculate was associated with deterioration of the mycelium development, dimorphism, and lowering of the yield of the biomass of the fungus.     

Prevalence of Abdominal Obesity in Spanish Children and Adolescents. Do We Need Waist Circumference Measurements in Pediatric Practice?

Background

Evidence indicates that central adiposity has increased to a higher degree than general adiposity in children and adolescents in recent decades. However, waist circumference is not a routine measurement in clinical practice.

Objective

This study aimed to determine the prevalence of abdominal obesity based on waist circumferences (WC) and waist to height ratio (WHtR) in Spanish children and adolescents aged 6 to 17 years. Further, the prevalence of abdominal obesity (AO) among normal and overweight individuals was analyzed.

Design

Data were obtained from a study conducted from 1998 to 2000 in a representative national sample of 1521 children and adolescents aged 6 to 17 years (50.0% female) in Spain. WC and WHtR measurements were obtained in addition to BMI. AO was defined as WHtR ≥0.50 (WHtR-AO), sex and age specific WC≥90^th percentile (WC-AO1), and sex and age specific WC cut-off values associated with high trunk fat measured by by dual-energy X-ray absorptiometry (WC-AO2).

Results

IOTF- based overweight and obsity prevalence was 21.5% and 6.6% in children and 17.4% and 5.2% in adolescents, respectively. Abdominal obesity (AO) was defined as WHtR≥0.50 (WHtR-AO), sex- and age-specific WC≥90th percentile (WC-AO1), and sex- and age-specific WC cut-off values associated with high trunk fat measured by dual-energy X-ray absorptiometry (WC-AO2). The respective prevalence of WHtR-AO, WC-AO1, and WC-AO2 was 21.3% (24.6% boys; 17.9% girls), 9.4% (9.1% boys; 9.7% girls), and 26.8% (30.6% boys;22.9% girls) in children and 14.3% (20.0% boys; 8.7% girls), 9.6% (9.8% boys; 9.5% girls), and 21.1% (28.8% boys; 13.7% girls) in adolescents.

Conclusion

The prevalence of AO in Spanish children and adolescents is of concern. The high proportion of AO observed in young patients who are normal weight or overweight indicates a need to include waist circumference measurements in routine clinical practice.