Generation of aroma compounds in sourdough: effects of stress exposure and lactobacilli-yeasts interactions

The effects of the interaction between Saccharomyces cerevisiae LBS and Lactobacillus sanfranciscensis LSCE1 and of their responses to acid, oxidative or osmotic stress on alcohol and aroma production were assessed. The exposure of S. cerevisiae LBS and L. sanfranciscensis LSCE1 cells to oxidative, acid or osmotic sub-lethal stress gave rise to a common or specific responses. Gamma-decalactone, 2(5H)-furanones and aldehydes were overproduced by LAB following oxidative stress. The acid stress induced both in yeasts and LAB, as well as in their co-cultures, a relevant accumulation of isovaleric and acetic acids and higher alcohols. A cross-exposure of yeasts and LAB to their preconditioned media, generated in S. cerevisiae a release of esters including esters of long-chain unsaturated fatty acids coming from membrane phospholipids. These esters were excreted also by yeasts following a pressure stress.     

Size-scaling in optical trapping of silicon nanowires

We investigate size-scaling in optical trapping of ultrathin silicon nanowires showing how length regulates their Brownian dynamics, optical forces, and torques. Force and torque constants are measured on nanowires of different lengths through correlation function analysis of their tracking signals. Results are compared with a full electromagnetic theory of optical trapping developed in the transition matrix framework, finding good agreement.     

Effect of wine addition on microbiological characteristics,volatile molecule profiles and biogenic amine contents in fermented sausages

The aim was to evaluate the effect of wine addition during manufacturing of dry fermented sausages, in terms of safety aspects (biogenic amine accumulation), aroma profile and sensory characteristics. Three batches of salami were produced: without wine addition and with 7.5% or 15% (v/w) of white wine. The fermented sausages showed characteristics that can increase product diversification. Some of the sensory features (i.e. increased salty perception) can represent an important strategy because of the trend to reduce salt intake for health reasons. The presence of wine immediately reduced the pH and is a source of ethanol, which can have an inhibitory effect against undesirable microflora. The microbiological results observed regarding Enterobacteriaceae and enterococci were encouraging. The addition of wine did not negatively affect the ripening time or increase the presence of biogenic amines. The samples containing wine showed reduced concentrations of putrescine.     

Antihypertensive activity of AMC3, an engineered 11S amaranth globulin expressed in Escherichia coli,in spontaneously hypertensive rats

The acidic-subunit of 11S seed storage globulin of Amaranthus hypochondriacus was recently modified by the incorporation of antihypertensive biopeptides: four units of Val–Tyr dipeptides (VY) in tandem and one of Ile–Pro–Pro tripeptide (IPP), was named AMC3. The in vivo effect of AMC3 enzymatic hydrolysates (AEH) produced in Escherichia coli, was evaluated in spontaneously hypertensive rats (SHR) by once-oral administration experiments. As positive control a SHR group received a dose of captopril (50 mg/kg) (an angiotensin-converting enzyme (ACE) inhibitor used for the treatment of hypertension). Mean arterial pressure (MAP) was measured for 6 h after AEH or captopril administration. AEH administration at maximal dose (100 mg/kg) significantly reduced MAP similar to the group treated with captopril. The maximal reduction in MAP was observed after 3.5 h after AEH oral administration. The present study showed that enzymatic hydrolysates of AMC3 containing ACE inhibitory peptides (4xVY and IPP) sequences had significant antihypertensive action by oral administration in spontaneously hypertensive rats (SHR).     

Stretch-Induced Activation of Pannexin 1 Channels Can Be Prevented by PKA-Dependent Phosphorylation

Pannexin 1 channels located in the cell membrane are permeable to ions, metabolites, and signaling molecules. While the activity of these channels is known to be modulated by phosphorylation on T198, T308, and S206, the possible involvement of other putative phosphorylation sites remains unknown. Here, we describe that the activity of Panx1 channels induced by mechanical stretch is reduced by adenosine via a PKA-dependent pathway. The mechanical stretch-induced activity—measured by changes in DAPI uptake—of Panx1 channels expressed in HeLa cell transfectants was inhibited by adenosine or cAMP analogs that permeate the cell membrane. Moreover, inhibition of PKA but not PKC, p38 MAPK, Akt, or PKG prevented the effects of cAMP analogs, suggesting the involvement of Panx1 phosphorylation by PKA. Accordingly, alanine substitution of T302 or S328, two putative PKA phosphorylation sites, prevented the inhibitory effect of cAMP analogs. Moreover, phosphomimetic mutation of either T302 or S328 to aspartate prevented the mechanical stretch-induced activation of Panx1 channels. A molecular dynamics simulation revealed that T302 and S328 are located in the water–lipid interphase near the lateral tunnel of the intracellular region, suggesting that their phosphorylation could promote conformational changes in lateral tunnels. Thus, Panx1 phosphorylation via PKA could be modulated by G protein-coupled receptors associated with the Gs subunit.     

The origin of photoluminescence in amorphous lead titanate

We discuss the nature of visible photoluminescence at room temperature in amorphous lead titanate in the light of the results of recent experimental and theoretical calculations. Experimental results obtained by XANES and EXAFS revealed that amorphous lead titanate is composed of a Ti-O network having fivefold Ti coordination and NBO-type (non-bridging oxygen) defects. These defects can modify the electronic structure of amorphous compounds. Our calculation of the electronic structure involved the use of first-principle molecular calculations to simulate the variation of the electronic structure in the lead titanate crystalline phase, which is known to have a direct band gap, and we also made an in-depth examination of amorphous lead titanate. The results of our theoretical calculations of amorphous lead titanate indicate that the formation of fivefold coordination in the amorphous system may introduce delocalized electronic levels in the HOMO (highest occupied molecular orbital) and the LUMO (lowest unoccupied molecular orbital). A comparison of the experimental and theoretical results of amorphous compounds suggests the possibility of a radiative recombination (electron-hole pairs), which may be responsible for the emission of photoluminescence.     

Applying transcriptomics to better understand the molecular mechanisms underlying fish filet quality

Microfluidic capillary electrophoresis and real-time PCR were successfully applied to investigate the postmortem alterations in RNA extracted from fish muscular tissue in relation to three parameters: slaughtering method, time, and storage temperature.     

Differential Effects of High-Fish Oil and High-Lard Diets on Cells and Cytokines Involved in the Inflammatory Process in Rat Insulin-Sensitive Tissues

Dietary fat sources may differentially affect the development of inflammation in insulin-sensitive tissues during chronic overfeeding. Considering the anti-inflammatory properties of ω-3 fatty acids, this study aimed to compare the effects of chronic high-fish oil and high-lard diets on obesity-related inflammation by evaluating serum and tissue adipokine levels and histological features in insulin-sensitive tissues (white adipose tissue, skeletal muscle and liver). As expected, a high-lard diet induced systemic and peripheral inflammation and insulin resistance. Conversely, compared with a high-lard diet, a high-fish oil diet resulted in a lower degree of systemic inflammation and insulin resistance that were associated with a lower adipocyte diameter as well as lower immunoreactivity for transforming growth factor β 1 (TGFβ1) in white adipose tissue. A high-fish oil diet also resulted in a lower ectopic lipid depot, inflammation degree and insulin resistance in the skeletal muscle and liver. Moreover, a high-fish oil diet attenuated hepatic stellate cell activation and fibrogenesis in the liver, as indicated by the smooth muscle α-actin (α-SMA) and TGFβ1 levels. The replacement of lard (saturated fatty acids) with fish oil (ω-3 fatty acids) in chronic high-fat feeding attenuated the development of systemic and tissue inflammation.