37 research outputs found
IGF2, LEPR, POMC, PPARG, and PPARGC1 gene variants are associated with obesity-related risk phenotypes in Brazilian children and adolescents.
Association studies of genetic variants and obesity and/or obesity-related risk factors have yielded contradictory results. The aim of the present study was to determine the possible association of five single-nucleotide polymorphisms (SNPs) located in the IGF2, LEPR, POMC, PPARG, and PPARGC1 genes with obesity or obesity-related risk phenotypes. This case-control study assessed overweight (n=192) and normal-weight (n=211) children and adolescents. The SNPs were analyzed using minisequencing assays, and variables and genotype distributions between the groups were compared using one-way analysis of variance and Pearson?s chi-square or Fisher?s exact tests. Logistic regression analysis adjusted for age and gender was used to calculate the odds ratios (ORs) for selected phenotype risks in each group. No difference in SNP distribution was
observed between groups. In children, POMC rs28932472(C) was associated with lower diastolic blood pressure (P=0.001), higher low-density lipoprotein (LDL) cholesterol (P=0.014), and higher risk in overweight children of altered total cholesterol (OR=7.35, P=0.006). In adolescents, IGF2 rs680(A) was associated with higher glucose (P=0.012) and higher risk in overweight adolescents for altered insulin (OR=10.08, P=0.005) and homeostasis model of insulin resistance (HOMA-IR) (OR=6.34, P=0.010). PPARG rs1801282(G) conferred a higher risk of altered insulin (OR=12.31, P=0.003), and HOMA-IR (OR=7.47, P=0.005) in overweight adolescents. PARGC1 rs8192678(A) was associated with higher triacylglycerols (P=0.005), and LEPR rs1137101(A) was marginally associated with higher LDL cholesterol (P=0.017). LEPR rs1137101(A) conferred higher risk for altered insulin, and HOMA-IR in overweight adolescents. The associations observed in this population suggested increased risk for cardiovascular diseases and/or type 2 diabetes later in life for individuals carrying these allele
Protective effect of ions against cell death induced by acid stress in Saccharomyces
Saccharomyces boulardii is a probiotic used to prevent or treat antibiotic-induced gastrointestinal disorders and acute enteritis. For probiotics to be effective they must first be able to survive the harsh gastrointestinal environment. In this work, we show that S. boulardii displayed the greatest tolerance to simulated gastric environments compared with several Saccharomyces cerevisiae strains tested. Under these conditions, a pH 2.0 was the main factor responsible for decreased cell viability. Importantly, the addition of low concentrations of sodium chloride (NaCl) protected cells in acidic conditions more effectively than other salts. In the absence of S. boulardii mutants, the protective effects of Na 1 in yeast viability in
acidic conditions was tested using S. cerevisiae Na 1 -ATPases (ena1-4), Na 1 /H 1 antiporter (nha1D) and Na 1 /H 1 antiporter prevacuolar (nhx1D) null mutants, respectively. Moreover, we provide evidence suggesting that this protection is determined by the plasma membrane potential, once altered by low pH and low NaCl concentrations. Additionally, the absence or low expression/activity of Ena proteins seems to be closely related to the basal membrane potential of the cells
Variable flocculation profiles of yeast strains isolated from cacha?a distilleries.
In cacha?a production, the use of yeast cells as starters with predictable flocculation behavior facilitates the cell recovery at the end of each fermentation cycle. Therefore, the aim of this work was to explain the behavior of cacha?a yeast strains in fermentation vats containing sugarcane through the determination of biochemical and molecular parameters associated with flocculation phenotypes. By analyzing thirteen cacha?a yeast strains isolated from different distilleries, our results demonstrated that neither classic biochemical measurements (e.g., percentage of flocculation, EDTA sensitivity, cell surface hydrophobicity, and sugar residues on the cell wall) nor modern molecular approaches, such as polymerase chain reaction (PCR) and real-time PCR (q-PCR), were sufficient to distinctly classify the cacha?a yeast strains according to their flocculation behavior. It seems that flocculation is indeed a strain-specific phenomenon that is difficult to explain and/or categorize by the available methodologie
Glycerol utilization in Fusarium oxysporum var lini : regulation of transport and metabolism.
Glycerol was transported in the fungus Fusarium oxysporum var. lini by a facilitated diffusion transport system
with a half-saturation constant, Ks, of 0.5 mM and a maximum velocity, Vmax, of 0.9 mmol (g dry wt)-l h-l at pH 5
and 25OC. 1,2-Propanediol was a competitive inhibitor of glycerol transport, but the cells did not actively
accumulate 1,2-propanediol. The transport system was partially constitutive. In cells grown in the presence of
glucose, glycerol was not transported, indicating that the synthesis of the system was under glucose repression.
Glycerol base and NADP+-dependent glycerol dehydrogenase activities were present under all physiological
conditions tested. A flavin-dependent glycerol phosphate dehydrogenase was induced only when glycerol was the
sole energy source in the medium. This enzyme, together with the transport system, constitute the regulated steps in
the glycerol metabolic pathway
Purification and characterization of an extracellular trypsin-like protease of Fusarium oxysporum var. lin.
An alkaline serineprotease, capable of hydrolyzing Nu-benzoyl-DL arginine p-nitroanilide, was
secreted by Fusurium oxysporum var. hi grown in the presence of gelatin as the sole nitrogen and
carbon source. The protease was purified 65-fold to electrophoretic homogenity from the culture
supernatant in a three-step procedure comprising QSepharose chromatography, aMnity chromatography,
and FPLC on a MonoQ column. SDS-PAGE analysis of the purified protein indicated
an estimated molecular mass of 41 kDa. The protease had optimum activity at a reaction
temperature of 45OC and showed a rapid decrease of activity at 48OC. The optimum pH was
around 8.0. Characterization of the protease showed that Ca*+ and MgZ+ cations increased the
activity, which was not inhibited by EDTA or l,lO-phenanthroline. The enzyme activity on Nubenzoyl-DL
arginine p-nitroanilide was inhibited by 4-(2-aminoethyl)-benzenesulfonyl fluoride
hydrochloride,p-aminobenzamidine dihydrochloride, aprotinin, 3-4 dichloroisocoumarin, and IVtosyl-L-lysine
chloromethyl ketone. The enzyme is also inhibited by substrate concentrations
higher than 2.5x lo-4 M. The protease had a Michaelis-Menten constant of 0.16 mM and a V,, of
0.60 pm01 released product .min-?.mg? enzyme when assayed in a non-inhibiting substrate concentration.
The activity on Nu-benzoyl-DL arginine p-nitroanilide was competitively inhibited by
p-aminobenzamidine dihydrochoride. A Ki value of 0.04 mM was obtained
Effect of substrate and pH on the activity of proteases from Fusarium oxysporum var. lini.
The results obtained in this work suggest that both the pH (through selective inhibition) and the carbon
source (through repression and acidification or alkalinization of the medium) may play an important role in
the distribution of extracellular proteases in Fusarium oxysporum var. lini
Glucose induced activation of the plasma membrane ATPase in Fusarium oxysporum.
Addition of glucose and other sugars to derepressed cells of the fungus Fusarium oxysporum var. Zini triggered
activation of the plasma membrane H+-ATPase within 5 min. Glucose was the best activator while galactose and
lactose had a lesser effect. The activation was not prevented by previous addition of cycloheximide and it was fully
reversible when the glucose was removed. The activation process in uiuo also caused changes in the kinetic
properties of the enzyme. The non-activated enzyme had an apparent K, of about 3.2 mM for ATP whereas the
activated enzyme showed an apparent K,,, of 0.26 mM. In addition, the pH optimum of the H+-ATPase changed
from 6.0 to 7.5 upon activation. The activated enzyme was more sensitive to inhibition by vanadate. When
F. oxysporum was cultivated in media containing glucose as the major carbon source, enhanced M+-ATPase
activity was largely confined to the period corresponding to the lag phase, i.e. just before the start of acidification of
the medium. This suggests that the activation process might play a role in the onset of extracellular acidification.
Addition of glucose to F. oxysporum var. Zini cells also caused an increase in the cAMP level. No reliable increase
could be demonstrated for the other sugars. Addition of proton ionophores such as DNP and CCCP at pH 5-0
caused both a large increase in the intracellular level of cAMP and in the activity of the plasma membrane H+-
ATPase. Inhibition of the DNP-induced increase in the cAMP level by acridine orange also resulted in inhibition of
the activation of plasma membrane H+-ATPase. These results suggest a possible causal relationship between the
activity of F. oxysporum var. Zini plasma membrane H+-ATPase and the intracellular level of CAMP
Yeast genes YOL002C and Sul1 are involved in neomycine resistance.
In previous studies we suggested the importance of the control of plasma membrane H+-ATPase by a phosphatidylinositol-like pathway for cellular proton extrusion in Saccharomyces cerevisiae (Brandão et al. 1994; Coccetti et al. 1998). The observations that provided the model above include the inhibition of the glucose-induced activation of the plasma membrane H+-ATPase as well as the inhibition of the glucose-induced external acidification by neomycin, a known inhibitor of the phosphatidylinositol turnover in eukaryotic cells. In this work, using two libraries, we isolated two yeast clones that were able to prevent the inhibition of glucose-induced activation of the H+-ATPase by neomycin. We show that the YOL002C gene, which encodes a protein of unknown function, and the SUL1 gene, which is a sulphate transporter belonging to the major facilitator superfamily, suppress growth inhibition by neomycin. However, they are not required for glucose-induced activation of the plasma membrane H+-ATPase. The resistance of the clones to neomycin is probably related to the level and/or activity of proteins functioning as drug extrusion pumps
Glucose-induced activation of plasma membrane H+-ATPase in mutants of the yeast Saccharomyces cerevisiae affected in cAMP metabolism, cAMP-dependent protein phosphorylation and the initiation of glycolysis.
Addition of glucose-related fermentable sugars or pro,tonophores to derepressed cells of the yeast Saccharomyces ceret'isiae causes a 3- to 4-fold activation of the plasma membrane H +-A'fPase within a few minutes. These conditions are known to cause rapid increases in the cAMP level. In yeast strains carrying temperature-sensitive mutations in genes required for cAMP
.~jnthesis, incohati~a at the restrictive temperature reduced the extent of H+-ATPase activation, Incubation of nontemperature- sensitive strains, however, at such temperatures also caused reduction of H +-ATPase activation. Yeast strains which are specifically deficient in the glucose-induced cAMP increase (and not in basal cAMP synthesis) still showed plasma membrane H+-ATPase aCtivation. Yeast mutants with widely divergent activity levels of cAMP-dependent protein kinase displayed very similar levels of activation of the plasma membrane H +-A'l'Pase. This was also true for a yeast mutant carrying a deletion in the CDC25 gene. These results show that the cAlVlP-protein kinase A signaling pathway is not required for glucose activation of the H*-ATPase. They also contradict the specific requirement of the CDC25 gene product. Experiments with yeast strains carrying point or deletion mutations in the genes coding for the sugar phnsphorylating enzymes hexokinase Pl and Pll and glucokinase
showed that activation of the H+-ATPase with glucose or fructose was completely dependent on the presence cf a kinase able m phnsphorylate the sugar. These and other data concerning the role of init,:al sugar metabolism in triggering activation are consistent with the idea that the glucose-induced activation pathways of cAMP-synthesis and H+-ATPase have a common initiation point
Glucose-induced activation of plasma membrane H+-ATPase in mutants of the yeast Saccharomyces cerevisiae affected in cAMP metabolism, cAMP-dependent protein phosphorylation and the initiation of glycolysis.
Addition of glucose-related fermentable sugars or pro,tonophores to derepressed cells of the yeast Saccharomyces ceret'isiae causes a 3- to 4-fold activation of the plasma membrane H +-A'fPase within a few minutes. These conditions are known to cause rapid increases in the cAMP level. In yeast strains carrying temperature-sensitive mutations in genes required for cAMP
.~jnthesis, incohati~a at the restrictive temperature reduced the extent of H+-ATPase activation, Incubation of nontemperature- sensitive strains, however, at such temperatures also caused reduction of H +-ATPase activation. Yeast strains which are specifically deficient in the glucose-induced cAMP increase (and not in basal cAMP synthesis) still showed plasma membrane H+-ATPase aCtivation. Yeast mutants with widely divergent activity levels of cAMP-dependent protein kinase displayed very similar levels of activation of the plasma membrane H +-A'l'Pase. This was also true for a yeast mutant carrying a deletion in the CDC25 gene. These results show that the cAlVlP-protein kinase A signaling pathway is not required for glucose activation of the H*-ATPase. They also contradict the specific requirement of the CDC25 gene product. Experiments with yeast strains carrying point or deletion mutations in the genes coding for the sugar phnsphorylating enzymes hexokinase Pl and Pll and glucokinase
showed that activation of the H+-ATPase with glucose or fructose was completely dependent on the presence cf a kinase able m phnsphorylate the sugar. These and other data concerning the role of init,:al sugar metabolism in triggering activation are consistent with the idea that the glucose-induced activation pathways of cAMP-synthesis and H+-ATPase have a common initiation point