Metabolism of Ethionine in Ethionine-Sensitive and Ethionine-Resistant Cells of the Enteric Yeast Candida slooffii

In a defined medium with added ethionine plus low methionine, phenylalanine, tryptophan, tyrosine, adenine, and additional methionine reversed inhibition of the enteric yeast Candida slooffii by ethionine. Isoleucine and 7-methylguanine restored half-maximal growth. Choline but not triethylcholine inhibited C. slooffii. 6-Mercaptopurine reversed ethionine inhibition and also synergistic inhibition by ethionine plus choline. Protection against ethionine by adenine plus aromatics was also evident with log-phase cells in the absence of methionine. Incorporation of ethionine-ethyl-1-(14)C by resting cells was partially inhibited by aromatic amino acids and methionine. Ethionine depressed incorporation of (3)H-phenylalanine but not of (3)H-adenine. Ethionine-resistant mutants were isolated which incorporated ethionine efficiently and degraded it to yet unidentified substances not including 5'-ethylthioadenosine. Ethionine-sensitive cells accumulated more S-adenosylethionine (SAE) than resistant mutants. Adenine was a good precursor of SAE. Radioactivity from ethionine-ethyl-1-(14)C was recovered from cell fractions of ethionine-sensitive cells with the following distribution: cold trichloroacetic acid-soluble > hot trichloroacetic acid-insoluble > lipids > deoxyribonucleic acid > ribonucleic acid. Total radioactivity recovered from ethionine-sensitive cells was twice as much as that from ethionine-resistant mutants.     

Metabolic Profile in Early Pregnancy Is Associated with Offspring Adiposity at 4 Years of Age: The Rhea Pregnancy Cohort Crete,Greece

ContextMaternal pre-pregnancy obesity may increase the risk of childhood obesity but it is unknown whether other metabolic factors in early pregnancy such as lipid profile and hypertension are associated with offspring cardiometabolic traits.ObjectiveOur objective was to investigate whether fasting lipid, glucose, and insulin levels during early pregnancy and maternal pre-pregnancy weight status, are associated with offspring adiposity measures, lipid levels and blood pressure at preschool age.ResultsPre-pregnancy overweight/obesity was associated with greater risk of offspring overweight/obesity (RR: 1.83, 95%CI: 1.19, 2.81), central adiposity (RR: 1.97, 95%CI: 1.11, 3.49), and greater fat mass by 5.10mm (95%CI: 2.49, 7.71) at 4 years of age. These associations were more pronounced in girls. An increase of 40mg/dl in fasting serum cholesterol levels in early pregnancy was associated with greater skinfold thickness by 3.30mm (95%CI: 1.41, 5.20) at 4 years of age after adjusting for pre-pregnancy BMI and several other confounders. An increase of 10mmHg in diastolic blood pressure in early pregnancy was associated with increased risk of offspring overweight/obesity (RR: 1.22, 95%CI: 1.03, 1.45), and greater skinfold thickness by 1.71mm (95% CI: 0.57, 2.86) at 4 years of age.ConclusionsMetabolic dysregulation in early pregnancy may increase the risk of obesity at preschool age.     

Yeast diversity and killer activity dispersed in fecal pellets from marsupials and rodents in a Brazilian tropical habitat mosaic

Yeasts with counts of above 10⁶ g⁻¹ wet weight and high diversity were found in the fecal pellets of rodents and marsupials from a mosaic of forest fragments, grasslands, cultivated fields and pasture in Rio de Janeiro. The most frequently isolated yeasts were Debaryomyces hamsenii, Pichia membranaefaciens and Issatchenkia orientalis (and its anamorph Candida krusei ), probably reflecting a high fruit content in the diet of these animals. The opportunistic pathogens Candida albicans, Candida glabrata and Candida tropicalis were isolated at lower frequency. Some Pichia anomala and P. membranaefaciens cultures had killer activity affecting many of the other isolates. These animals can be involved in dispersal of yeasts.     

Cytoplasmic inheritance and intragenomic conflict

The differing inheritance patterns of cytoplasmic genes and the sex chromosomes from the Mendelian autosomal patterns can be used to divide the genome into fractions whose defining rule is that the fitness of all genes in a set is maximized in the same way. Each set will be selected to modify the phenotype of the organism in a way which maximally propagates the genes comprising the set, and hence in ways inconsistent with the other sets which comprise the total genome. The coexistence of such multiple sets in the same genome creates intragenomic conflict. Evidence is presented in which the fitness of cytoplasmic and other non-autosomal genetic sets are increased at the expense of the autosomal genetic set. The relationship of such intragenomic conflict to the evolution of anisogamy, dioecy, skewed sex ratios, differential male mortality, systems of sex determination, and altruism is discussed.     

Dynamics of fungal communities in bulk and maize rhizosphere soil in the tropics

The fungal population dynamics in soil and in the rhizospheres of two maize cultivars grown in tropical soils were studied by a cultivation-independent analysis of directly extracted DNA to provide baseline data. Soil and rhizosphere samples were taken from six plots 20, 40, and 90 days after planting in two consecutive years. A 1.65-kb fragment of the 18S ribosomal DNA (rDNA) amplified from the total community DNA was analyzed by denaturing gradient gel electrophoresis (DGGE) and by cloning and sequencing. A rhizosphere effect was observed for fungal populations at all stages of plant development. In addition, pronounced changes in the composition of fungal communities during plant growth development were found by DGGE. Similar types of fingerprints were observed in two consecutive growth periods. No major differences were detected in the fungal patterns of the two cultivars. Direct cloning of 18S rDNA fragments amplified from soil or rhizosphere DNA resulted in 75 clones matching 12 dominant DGGE bands. The clones were characterized by their HinfI restriction patterns, and 39 different clones representing each group of restriction patterns were sequenced. The cloning and sequencing approach provided information on the phylogeny of dominant amplifiable fungal populations and allowed us to determine a number of fungal phylotypes that contribute to each of the dominant DGGE bands. Based on the sequence similarity of the 18S rDNA fragment with existing fungal isolates in the database, it was shown that the rhizospheres of young maize plants seemed to select the Ascomycetes order Pleosporales, while different members of the Ascomycetes and basidiomycetic yeast were detected in the rhizospheres of senescent maize plants.     

Maintenance of pluripotency in mouse embryonic stem cells cultivated in stirred microcarrier cultures

The development of efficient and reproducible culture systems for embryonic stem (ES) cells is an essential pre‐requisite for regenerative medicine. Culture scale‐up ensuring maintenance of cell pluripotency is a central issue, because large amounts of pluripotent cells must be generated to warrant that differentiated cells deriving thereof are transplanted in great amounts and survive the procedure. This study aimed to develop a robust scalable cell expansion system, using a murine embryonic stem cell line that is feeder‐dependent and adapted to serum‐free medium, thus representing a more realistic model for human ES cells. We showed that high concentrations of murine ES cells can be obtained in stirred microcarrier‐based spinner cultures, with a 10‐fold concentration of cells per volume of medium and a 5‐fold greater cell concentration per surface area, as compared to static cultures. No differences in terms of pluripotency and differentiation capability were observed between cells grown in traditional static systems and cells that were replated onto the traditional system after being expanded on microcarriers in the stirred system. This was verified by morphological analyses, quantification of cells expressing important pluripotency markers (Oct‐4, SSEA‐1, and SOX2), karyotype profile, and the ability to form embryoid bodies with similar sizes, and maintaining their intrinsic ability to differentiate into all three germ layers. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010